Lithium nickel-based composite oxide as positive electrode active material for sulfide solid state rechargeable batteries

Abstract

The invention relates to a positive electrode active material for a solid state battery, said positive electrode active material comprising Li, M'and O, where M 'comprises Si and / or Zr. The present inventors have unexpectedly found that the positive electrode active material according to the invention increases the cycle efficiency of said batteries, in particular sulfide solid state batteries. In addition, these coated positive electrode active materials exhibit higher first discharge capacities.

Description

Technical Field

[0001] The present invention relates to a positive electrode active material for a solid-state secondary battery, the positive electrode active material containing Li, M' and O, where M' includes Si and / or Zr. The present invention also relates to a method for manufacturing the positive electrode active material, a solid-state secondary battery including the positive electrode active material, and the use of the solid-state secondary battery. Background Art

[0002] With the rapid development of small and light electronic products, electronic devices, communication devices, etc. and the widespread emergence of the demand for electric vehicles in terms of environmental issues, it is necessary to improve the performance of secondary batteries used as power sources for these products. Among them, lithium secondary batteries have become the focus as high-performance batteries due to their high energy density and high reference electrode potential.

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

[0004] Commonly used cathode active materials are lithium transition metal oxides. During the charging and / or discharging process 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 decline in the electrochemical performance of the lithium battery using such a cathode active material.

[0005] It has been demonstrated that coating a cathode active material with a metal (i.e., applying a thin surface layer of the metal on the cathode active material to increase the amount of the metal in the surface layer) can make the cathode active material exhibit higher stability compared to the corresponding cathode active material without the coating layer.

[0006] Strauss et al. (ACS Appl. Mater. Interfaces 2020, 12, 51, 57146–57154) envisioned a lithium nickel-based oxide positive electrode active material that contains a Zr compound obtained after mixing a positive electrode active material containing Li, M' and O with zirconium ethoxide in an ethanol solvent, where M' is Ni 0.6 Co 0.2 Mn 0.2 .

[0007] US 10,164,249 B2 discloses mixing a Zr- and F-doped positive electrode active material with a solution of tetraethyl orthosilicate in ethanol, followed by heat treatment at 160 °C to remove the ethanol and sintering at 850 °C to obtain the positive electrode active material.

[0008] However, there is still a need to provide a positive electrode active material containing Si and / or Zr to improve the first discharge capacity and / or cycle efficiency of the resulting storage battery.

[0009] One object of the present invention is to provide a positive electrode active material containing Si and / or Zr to improve the first discharge capacity and / or cycle efficiency of the resulting storage battery.

[0010] Another object of the present invention is to provide a method for manufacturing the positive electrode active material.

[0011] Another object of the present invention is to provide a storage battery containing the positive electrode active material.

[0012] Another object of the present invention is to provide the use of the storage battery. Summary of the Invention

[0013] In a first aspect, an object of the present invention is achieved by providing a positive electrode active material for a solid-state storage battery, the positive electrode active material containing Li, M', and O, where M' includes:

[0014] - Ni with a content of x, where 50.0 mol% ≤ x ≤ 95.0 mol% relative to M',

[0015] - Mn with a content of y, where 0.0 mol% ≤ y ≤ 30.0 mol% relative to M',

[0016] - Co with a content of z, where 0.0 mol% ≤ z ≤ 30.0 mol% relative to M',

[0017] - Si with a content of a, where 0.01 mol% ≤ a ≤ 1.5 mol% relative to M',

[0018] - Zr with a content of b, where 0.0 mol% ≤ b ≤ 1.5 mol% relative to M',

[0019] - D with a content of d, where D is an element other than Li, Ni, Mn, Co, Si, Zr, and O; where 0.0 mol% ≤ d ≤ 2.0 mol% relative to M', and,

[0020] - where x, y, z, a, b, and d are measured by ICP-OES,

[0021] - where x + y + z + a + b + d = 100.0 mol%.

[0022] Wherein the positive electrode active material has an enriched amount of Si and / or Zr in the surface layer.

[0023] In other words, the positive electrode active material of the present invention has a surface layer containing Si and / or Zr.

[0024] The inventors have unexpectedly found that the positive electrode active material of the present invention improves the cycle efficiency of a storage battery, particularly a sulfide solid-state storage battery, as confirmed by the attached examples. In addition, these coated positive electrode active materials exhibit a higher initial discharge capacity.

[0025] Preferably, the coated positive electrode active material containing Si and Zr is superior to the corresponding coated positive electrode material containing Zr but not Si in terms of the initial charge-discharge capacity and cycle efficiency.

[0026] Preferably, the coated positive electrode active material containing Si and Zr is superior to the corresponding coated positive electrode material containing Si but not Zr in terms of the initial charge-discharge capacity and cycle efficiency. In addition, the coated positive electrode active material containing Si and Zr is superior to the corresponding coated positive electrode material containing Zr but not Si in terms of the initial charge-discharge capacity and cycle efficiency.

[0027] The positive electrode active material of the present invention containing a specific amount of Si and Zr in the surface layer has the following advantages compared to the positive electrode active material containing the same specific amount of Zr: the resulting storage battery has a higher discharge capacity and / or a higher cycle efficiency. The advantage of this is that a part of Zr in the surface layer can be replaced by Si (Si is a more abundant and cheaper metal than Zr), thereby obtaining a storage battery having the same or even higher discharge capacity and / or the same or higher cycle efficiency.

[0028] Preferably, the coated positive electrode active material containing Si but not Zr is superior to the corresponding coated positive electrode material containing Zr but not Si in terms of the initial charge-discharge capacity and cycle efficiency.

[0029] The positive electrode active material of the present invention containing a specific amount of Si (but not Zr) in the surface layer has the following advantages compared to the positive electrode active material containing the same specific amount of Zr: the resulting storage battery has a higher discharge capacity and / or a higher cycle efficiency. The advantage of this is that all of Zr in the surface layer can be replaced by Si (Si is a more abundant and cheaper metal than Zr), thereby obtaining a storage battery having the same or even higher discharge capacity and / or the same or higher cycle efficiency.

[0030] In addition, the present inventors have found that the positive electrode active material of the present invention containing Si or containing Si and Zr improves storage stability. Specifically, a reduction in the absorption of water and carbon (or carbon dioxide) can be observed by applying a surface layer of Si onto the positive electrode active material. Without wishing to be bound by any theory, the present inventors believe that the surface layer of Si acts as a hydrophobic surface layer, which inhibits the formation of residual lithium compounds (such as Li2CO3), which are formed due to the reaction between lithium present in the positive electrode active material and water and carbon in the surrounding air, because the hydrophobic surface inhibits the contact between water and the positive electrode active material.

[0031] In another aspect, the present invention provides a method for manufacturing the positive electrode active material.

[0032] In another aspect, the present invention provides a storage battery comprising the positive electrode active material.

[0033] In another aspect, the present invention provides the use of the storage battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 .XPS peaks of Si and Zr in EX1.1 DETAILED DESCRIPTION

[0035] In the following detailed description, preferred embodiments are described in detail so that the present invention can be practiced. 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 equivalents, which will become apparent by considering the following detailed description and the drawings.

[0036] As used herein and in the claims, the term "comprising" should not be construed as limited to the components 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 components A and B" should not be limited to a composition consisting only of components A and B. This means that for the purposes of the present invention, the only relevant components of the composition are A and B. Thus, the terms "comprising" and "including" encompass the more restrictive terms "consisting essentially of" and "consisting of".

[0037] The term "solid-state storage battery" as used herein and in the claims refers to a battery or storage 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).

[0038] 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. By active material, it must be understood a material that is capable of capturing and releasing Li ions when subjected to a voltage change over a predetermined period of time.

[0039] As used herein, the term "positive electrode" is defined as a material that comprises a positive electrode active material and other components that are not electrochemically active (in particular, a conductive agent such as carbon black or a binder such as PVDF).

[0040] 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, an alcohol, or a combination thereof). When the term "slurry" is used, the solid particles are not dissolved or are not completely 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 not completely dissolved in the liquid.

[0041] In the context of the present invention, unless otherwise defined, the terms "solid" and "liquid" shall be considered to be a solid and a liquid under standard temperature conditions and standard pressure conditions as defined by IUPAC. Accordingly, the boiling point and melting point shall be considered to be the boiling point and melting point under standard atmospheric pressure, i.e., at 101325 Pa.

[0042] Positive electrode active material

[0043] In a first aspect, the present invention relates to a positive electrode active material for a solid-state storage battery, the positive electrode active material comprising Li, M', and O, where M' comprises:

[0044] - Ni in an amount of x, where 50.0 mol% ≤ x ≤ 95.0 mol% relative to M',

[0045] - Mn in an amount of y, where 0.0 mol% ≤ y ≤ 30.0 mol% relative to M',

[0046] - Co in an amount of z, where 0.0 mol% ≤ z ≤ 30.0 mol% relative to M',

[0047] - Si in an amount of a, where 0.01 mol% ≤ a ≤ 1.5 mol% relative to M',

[0048] - Zr in an amount of b, where 0.0 mol% ≤ b ≤ 1.5 mol% relative to M',

[0049] - D with a content of d, where D is an element other than Li, Ni, Mn, Co, Si, Zr, and O; where 0.0 mol% ≤ d ≤ 2.0 mol% relative to M', and,

[0050] - where x, y, z, a, b, and d are measured by ICP-OES,

[0051] - where x + y + z + a + b + d = 100.0 mol%,

[0052] where the positive electrode active material has an Si content of Si A , the Si A is defined as a / (x + y + z + a + b),

[0053] where the positive electrode active material has an Si content of Si B , where Si B is expressed as the ratio of the mole fraction of Si to the sum of the mole fractions of Ni, Mn, Co, Si, and Zr, as measured by XPS analysis, where the ratio Si B / Si A > 50.0.

[0054] A preferred embodiment is the positive electrode active material of the present invention, where the content of Ni is x ≥ 55.0 mol% relative to M', preferably x ≥ 58.0 mol%, more preferably x ≥ 60.0 mol%. In a preferred embodiment, the content of Ni is x ≤ 90.0 mol% relative to M', preferably x ≤ 88 mol%, more preferably x ≤ 85.0 mol%. A more preferred embodiment is the positive electrode active material of the present invention, where the content of Ni, x, is between 55.0 mol% ≤ x ≤ 90.0 mol%, preferably between 58.0 mol% ≤ x ≤ 88.0 mol%, more preferably between 60.0 mol% ≤ x ≤ 85.0 mol%.

[0055] A specific preferred embodiment is the positive electrode active material of the present invention, where the content of Ni is x ≥ 55.0 mol% relative to M', preferably x ≥ 58.0 mol%, more preferably x ≥ 60.0 mol%. In a specific preferred embodiment, the content of Ni is x ≤ 75.0 mol% relative to M', preferably x ≤ 72 mol%, more preferably x ≤ 70.0 mol%. A specific more preferred embodiment is the positive electrode active material of the present invention, where the content of Ni, x, is between 55.0 mol% ≤ x ≤ 75.0 mol%, preferably between 58.0 mol% ≤ x ≤ 72.0 mol%, more preferably between 60.0 mol% ≤ x ≤ 70.0 mol%.

[0056] A specific preferred embodiment is the positive electrode active material of the present invention, wherein the content of Ni is x ≥ 75.0 mol%, preferably x ≥ 78.0 mol%, more preferably x ≥ 80.0 mol% relative to M'. In a specific preferred embodiment, the content of Ni is x ≤ 92.0 mol%, preferably x ≤ 90 mol%, more preferably x ≤ 88.0 mol% relative to M'. A specific more preferred embodiment is the positive electrode active material of the present invention, wherein the content of Ni, x, is between 75.0 mol% ≤ x ≤ 92.0 mol%, preferably between 78.0 mol% ≤ x ≤ 90.0 mol%, more preferably between 80.0 mol% ≤ x ≤ 88.0 mol% relative to M'.

[0057] As understood by those skilled in the art, the amounts of Li and M' (preferably Li, Ni, Mn, Co, D, Si, and Zr) in the positive electrode active material are measured by inductively coupled plasma optical emission spectrometry (ICP-OES). For example, but not limited to the present invention, Agilent ICP 720-ES is used in the ICP-OES analysis.

[0058] A preferred embodiment is the positive electrode active material of the present invention, wherein the content of Mn is y > 0.0 mol%, preferably y ≥ 5.0 mol%, more preferably y ≥ 10.0 mol% relative to M'. In a preferred embodiment, the content is y ≤ 30.0 mol%, preferably y ≤ 25.0 mol%, and more preferably y ≤ 20.0 mol% relative to M'. In a preferred embodiment, the content of Mn is 0.0 mol% < y ≤ 30.0 mol%, preferably 5.0 mol% ≤ y ≤ 25.0 mol%, more preferably 10.0 mol% ≤ y ≤ 20.0 mol% relative to M'.

[0059] A specific preferred embodiment is the positive electrode active material of the present invention, wherein the content of Mn is y > 0.0 mol%, preferably y ≥ 1.0 mol%, more preferably y ≥ 2.0 mol% relative to M'. In a preferred embodiment, the content is y ≤ 20.0 mol%, preferably y ≤ 15.0 mol%, and more preferably y ≤ 10.0 mol% relative to M'. In a preferred embodiment, the content of Mn is 0.0 mol% < y ≤ 20.0 mol%, preferably 1.0 mol% ≤ y ≤ 15.0 mol%, more preferably 2.0 mol% ≤ y ≤ 10.0 mol% relative to M'.

[0060] A preferred embodiment is the positive electrode active material of the present invention, wherein the content of Co is z > 0.0 mol%, preferably z ≥ 5.0 mol%, more preferably z ≥ 10.0 mol% relative to M'. In a preferred embodiment, the content is z ≤ 30.0 mol%, preferably z ≤ 25.0 mol%, and more preferably z ≤ 20.0 mol% relative to M'. In a preferred embodiment, the content of Co is 0.0 mol% < z ≤ 30.0 mol%, preferably 5.0 mol% ≤ z ≤ 25.0 mol%, more preferably 10.0 mol% ≤ z ≤ 20.0 mol% relative to M'.

[0061] A specific preferred embodiment is the positive electrode active material of the present invention, wherein the content of Co is z > 0.0 mol%, preferably z ≥ 1.0 mol%, more preferably z ≥ 2.0 mol% relative to M'. In a preferred embodiment, the content is z ≤ 20.0 mol%, preferably z ≤ 15.0 mol%, and more preferably z ≤ 10.0 mol% relative to M'. In a preferred embodiment, the content of Co is 0.0 mol% < z ≤ 20.0 mol%, preferably 1.0 mol% ≤ z ≤ 15.0 mol%, more preferably 2.0 mol% ≤ z ≤ 10.0 mol% relative to M'.

[0062] 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 coated, so that the entire positive electrode active material contains one or more elements other than Li, Ni, Mn, Co, Zr, Si, and O, which is reflected in the parameter "D" used herein. A preferred embodiment is the positive electrode active material of the present invention containing D, wherein D is at least one element selected from the group consisting of: Al, B, Ba, Ca, Ce, Cr, Fe, La, Mg, Mo, Nb, S, Sr, Ti, V, W, Y, and Zn; preferably Al, B, Ti, Cr, Nb, S, Y, and W; more preferably Al, B, Ti, Nb, and W.

[0063] A preferred embodiment is the positive electrode active material according to the present invention, wherein the content of D is d > 0.0 mol%, preferably d ≥ 0.25 mol%, more preferably d ≥ 0.5 mol% relative to M'. In a preferred embodiment, the content d ≤ 1.75 mol%, preferably d ≤ 1.5 mol%, more preferably d ≤ 1.25 mol% relative to M'. In a preferred embodiment, the content d is 0.0 mol% < d ≤ 1.75 mol%, preferably 0.25 mol% ≤ d ≤ 1.5 mol%, more preferably 0.5 mol% ≤ d ≤ 1.25 mol% relative to M'.

[0064] In certain preferred embodiments, the positive electrode active material is the positive electrode active material according to the present invention, wherein d = 0.0 mol% relative to M'.

[0065] One preferred embodiment is the positive electrode active material according to the present invention, wherein the content of Si is a > 0.03 mol% relative to M', preferably a ≥ 0.05 mol%, more preferably a ≥ 0.07 mol%. In one preferred embodiment, relative to M', the content a ≤ 1.0 mol%, preferably a ≤ 0.75 mol%, more preferably a ≤ 0.5 mol%. In one preferred embodiment, relative to M', the content a is 0.03 mol% < a ≤ 1.0 mol%, preferably 0.05 mol% ≤ a ≤ 0.75 mol%, more preferably 0.07 mol% ≤ a ≤ 0.5 mol%.

[0066] In certain preferred embodiments, the positive electrode active material is the positive electrode active material according to the present invention, wherein b > 0.0 mol% relative to M'.

[0067] A particularly highly preferred embodiment is the positive electrode active material according to the present invention, wherein the content of Zr is b > 0.0 mol% relative to M', preferably b ≥ 0.05 mol%, more preferably b ≥ 0.1 mol%. In one preferred embodiment, relative to M', the content b ≤ 1.0 mol%, preferably b ≤ 0.5 mol%, more preferably b ≤ 0.25 mol%. In one preferred embodiment, relative to M', the content b is 0.0 mol% < b ≤ 1.0 mol%, preferably 0.05 mol% ≤ b ≤ 0.5 mol%, more preferably 0.1 mol% ≤ b ≤ 0.25 mol%.

[0068] In certain preferred embodiments, the positive electrode active material is the positive electrode active material according to the present invention, wherein b = 0.0 mol% relative to M'.

[0069] In one preferred embodiment, the positive electrode active material consists of Li, M' and O.

[0070] In certain preferred embodiments, the positive electrode active material is the positive electrode active material according to the present invention,

[0071] · wherein the content of Si is 0.03 mol% < a ≤ 1.0 mol% relative to M', preferably 0.05 mol% ≤ a ≤ 0.75 mol%, more preferably 0.07 mol% ≤ a ≤ 0.5 mol%, and

[0072] · wherein b = 0.0 mol% relative to M'.

[0073] One preferred embodiment is the positive electrode active material of the present invention, the positive electrode active material having a carbon content greater than 0.020% by weight of the total weight of the positive electrode active material, preferably a carbon content greater than 0.022% by weight of the total weight of the positive electrode active material, more preferably a carbon content greater than 0.025% by weight of the total weight of the positive electrode active material. One preferred embodiment is the positive electrode active material of the present invention, the positive electrode active material having a carbon content less than 0.070% by weight of the total weight of the positive electrode active material, preferably a carbon content less than 0.060% by weight of the total weight of the positive electrode active material, more preferably a carbon content less than 0.050% by weight of the total weight of the positive electrode active material. One preferred embodiment is the positive electrode active material of the present invention, the positive electrode active material having a carbon content in the range of 0.020% by weight and 0.070% by weight of the total weight of the positive electrode active material, preferably a carbon content in the range of 0.022% by weight and 0.060% by weight of the total weight of the positive electrode active material, more preferably a carbon content in the range of 0.025% by weight and 0.050% by weight of the total weight of the positive electrode active material. As understood by those skilled in the art, the carbon content of the positive electrode active material of the present invention is measured using a carbon analyzer. For example, but not limited to the present invention, a Horiba Emia-Expert carbon / sulfur analyzer can be used to measure the carbon content.

[0074] One preferred embodiment is the positive electrode active material of the present invention, the positive electrode active material having an Li / M' ratio, preferably an Li / (Ni + Mn + Co) ratio > 0.90, preferably > 0.92, more preferably > 0.95. One preferred embodiment is the positive electrode active material of the present invention, the positive electrode active material having an Li / M' ratio, preferably an Li / (Ni + Mn + Co) ratio < 1.10, preferably < 1.08, more preferably < 1.05. One preferred embodiment is the positive electrode active material of the present invention, the positive electrode active material having an Li / M' ratio, preferably an Li / (Ni + Mn + Co) ratio in the range of 0.90 - 1.10, preferably in the range of 0.92 - 1.08, more preferably in the range of 0.95 - 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).

[0075] A highly preferred embodiment is the positive electrode active material according to the present invention having the formula (I):

[0076] Li w2 Ni x2 Mn y2 Co z2 Si a2 Zr b2 D2d2 O2(I)

[0077] where 0.90 ≤ w2 ≤ 1.10, preferably 0.92 ≤ w2 ≤ 1.08, more preferably 0.95 ≤ w2 ≤ 1.05;

[0078] where 0.55 ≤ x2 ≤ 0.90, preferably 0.58 ≤ x2 ≤ 0.88, more preferably 0.60 ≤ x2 ≤ 0.85;

[0079] where 0.0 < y2 ≤ 0.30, preferably 0.05 ≤ y2 ≤ 0.25, more preferably 0.10 ≤ y2 ≤ 0.20;

[0080] where 0.0 < z2 ≤ 0.30, preferably 0.05 ≤ z2 ≤ 0.25, more preferably 0.10 ≤ z2 ≤ 0.20;

[0081] where 0.0003 ≤ a2 ≤ 0.01, preferably 0.0005 ≤ a2 ≤ 0.0075, more preferably 0.0007 ≤ a2 ≤ 0.005;

[0082] where 0.0 < b2 ≤ 0.01, preferably 0.0005 ≤ b2 ≤ 0.005, more preferably 0.0001 ≤ b2 ≤ 0.0025;

[0083] where 0.0 ≤ d2 ≤ 0.0175, preferably 0.0 ≤ d2 ≤ 0.015, more preferably 0.0 ≤ d2 ≤ 0.0125, and most preferably d2 is about 0.0;

[0084] where x2 + y2 + z2 + a2 + b2 + d2 = 1.00; and

[0085] where D2 is an element other than Li, O, Ni, Co, Mn, Z, and Si.

[0086] In a certain preferred embodiment, 0.55 ≤ x2 ≤ 0.75, preferably 0.58 ≤ x2 ≤ 0.72, more preferably 0.60 ≤ x2 ≤ 0.70.

[0087] 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 coated, so that the entire positive electrode active material contains one or more elements other than Li, Ni, Mn, Co, Zr, Si, and O, which is reflected in the parameter "D2" used herein. A preferred embodiment is the positive electrode active material according to the present invention containing D2, where D2 is at least one element selected from the group consisting of: Al, B, Ba, Ca, Ce, Cr, Fe, La, Mg, Mo, Nb, S, Sr, Ti, V, W, Y, and Zn; preferably Al, B, Ti, Cr, Nb, S, Y, and W; more preferably Al, B, Ti, Nb, and W.

[0088] Surface layer

[0089] The present invention provides a positive electrode active material according to the present invention, wherein the positive electrode active material has a Si content Si A , the Si A is defined as a / (x + y + z + a + b), where the positive electrode active material has a Si content Si B , where Si B is expressed as the ratio of the mole fraction of Si to the sum of the mole fractions of Ni, Mn, Co, Si, and Zr, as measured by XPS analysis, where the ratio Si B / Si A > 50.0.

[0090] A more preferred embodiment relates to a positive electrode active material according to the present invention, where the ratio Si B / Si A > 100.0, preferably where the ratio Si B / Si A > 200.0, more preferably where the ratio Si B / Si A > 250.0. A more preferred embodiment relates to a positive electrode active material according to the present invention, where the ratio Si B / Si A < 1000.0, preferably where the ratio Si B / Si A < 600.0, more preferably where the ratio Si B / Si A < 400.0. A more preferred embodiment relates to a positive electrode active material according to the present invention, where the ratio Si B / Si A is in the range of 100.0 and 1000.0, preferably where the ratio Si B / Si AIn the range of 200.0 and 600.0, more preferably where the ratio Si B / Si A is in the range of 250.0 and 400.0.

[0091] Certain preferred embodiments relate to a positive electrode active material according to the present invention, where the ratio Si B / Si A > 300.0. Certain preferred embodiments relate to a positive electrode active material according to the present invention, where the ratio Si B / Si A < 400.0. Certain preferred embodiments relate to a positive electrode active material according to the present invention, where the ratio Si B / Si A is in the range of 300.0 and 400.0.

[0092] In the context of the present invention, Si B is the mole fraction of Si measured in the particle region of the positive electrode active material according to the present invention, which region is defined between a first point on the outer edge of the particle and a second point at a certain distance from the first point. The distance between the first point and the second point is equal to the penetration depth of the XPS, and the penetration depth D' is between 1.0 nm and 10.0 nm. Specifically, 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.

[0093] Within 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. Thus, XPS analysis provides the atomic content of the elements in the uppermost layer of the particle that penetrates about 10.0 nm from the outer boundary of the particle at a depth of 30. 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).

[0094] Within the framework of the present invention, at.% represents atomic percentage. The at.% or "atomic percentage" of a given element of a concentration means what percentage of all the atoms in the relevant compound are atoms of that element. In addition, within the framework of the present invention, the symbol at.% is equivalent to mol% or "mole percentage".

[0095] As understood by those skilled in the art, the defined ratio Si B / Si AIt means that the positive electrode active material of the present invention has an enriched amount of Si in the surface layer of the positive electrode active material. 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 Si. For example, but not limited to the present invention, the compound of Si present in the surface layer of the positive electrode active material is Li2SiO3.

[0096] 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, Ce, Cr, Fe, La, Mg, Mo, Nb, S, Sr, Ti, V, W, Y, and Zn; preferably Al, B, Ti, Cr, Nb, S, Y, and W; more preferably Al, B, Ti, Nb, and W, where the surface layer of Si may be located on the first surface layer and / or the first surface layer may be located on the surface layer of Si and / or the positive electrode active layer may include a mixed surface layer including the surface layer of Si and the first surface layer.

[0097] One preferred embodiment relates to a positive electrode active material according to the present invention, wherein the positive electrode active material has a Zr content Zr A , the Zr A is defined as b / (x + y + z + a + b), where the positive electrode active material has a Zr content Zr B , where Zr B is expressed as the ratio of the molar fraction of Zr to the sum of the molar fractions of Ni, Mn, Co, Si, and Zr, as measured by XPS analysis, where the ratio Zr B / Zr A > 50.0.

[0098] A more preferred embodiment relates to a positive electrode active material according to the present invention, wherein the ratio Zr B / Zr A > 75.0, preferably where the ratio Zr B / Zr A > 100.0, more preferably where the ratio Zr B / Zr A > 150.0. A more preferred embodiment relates to a positive electrode active material according to the present invention, wherein the ratio Zr B / Zr A < 1000.0, preferably where the ratio Zr B / Zr A < 600.0, more preferably where the ratio Zr B / Zr A<400.0. A more preferred embodiment relates to a positive electrode active material according to the present invention, wherein the ratio Zr B / Zr A is in the range of 75.0 and 1000.0, preferably wherein the ratio Zr B / Zr A is in the range of 100.0 and 600.0, more preferably wherein the ratio Zr B / Zr A is in the range of 150.0 and 400.0.

[0099] Certain preferred embodiments relate to a positive electrode active material according to the present invention, wherein the ratio Zr B / Zr A > 275.0. Certain preferred embodiments relate to a positive electrode active material according to the present invention, wherein the ratio Zr B / Zr A < 350.0. Certain preferred embodiments relate to a positive electrode active material according to the present invention, wherein the ratio Zr B / Zr A is in the range of 275.0 and 350.0.

[0100] In the context of the present invention, Zr B is the mole fraction of Zr measured in the particle region of the positive electrode active material according to the present invention, which region is defined between a first point on the outer edge of the particle and a second point at a certain distance from the first point. The distance between the first point and the second point is equal to the penetration depth of the XPS, and the penetration depth D' is between 1.0 nm and 10.0 nm. Specifically, 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.

[0101] As understood by those skilled in the art, the defined ratio Zr B / Zr A means that the positive electrode active material of the present invention has an enriched amount of Zr in the surface layer of the positive electrode active material. 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 Zr. For example, but not limited to the present invention, the compound of Zr present in the surface layer of the positive electrode active material is Li2ZrO3.

[0102] In the context of the present invention, the positive electrode active material may include a second surface layer containing D, where D is at least one element selected from the group consisting of: Al, B, Ba, Ca, Ce, Cr, Fe, La, Mg, Mo, Nb, S, Sr, Ti, V, W, Y, and Zn; preferably Al, B, Ti, Cr, Nb, S, Y, and W; more preferably Al, B, Ti, Nb, and W, where the surface layer of Zr may be located on the second surface layer and / or the second surface layer may be located on the surface layer of Zr and / or the positive electrode active layer may include a mixed surface layer including the surface layer of Zr and the second surface layer.

[0103] A particular preferred embodiment relates to a positive electrode active material according to the present invention, wherein the positive electrode active material has

[0104] · A Si content Si A , the Si A being defined as a / (x + y + z + a + b), where the positive electrode active material has a Si content Si B , where Si B is expressed as the ratio of the mole fraction of Si to the sum of the mole fractions of Ni, Mn, Co, Si, and Zr, as measured by XPS analysis, where the ratio Si B / Si A > 50.0, preferably where the ratio Si B / Si A > 100; and

[0105] · The positive electrode active material has a Zr content Zr A , the Zr A being defined as b / (x + y + z + a + b), where the positive electrode active material has a Zr content Zr B , where Zr B is expressed as the ratio of the mole fraction of Zr to the sum of the mole fractions of Ni, Mn, Co, Si, and Zr, as measured by XPS analysis, where the ratio Zr B / Zr A > 50.0, preferably where the ratio Zr B / Zr A > 100.

[0106] A particular more preferred embodiment relates to a positive electrode active material according to the present invention,

[0107] · Where the ratio Si B / Si A is in the range of 100.0 and 1000.0, preferably where the ratio Si B / SiA In the range of 200.0 and 600.0, more preferably where the ratio Si B / Si A is in the range of 250.0 and 400.0; and

[0108] · where the ratio Zr B / Zr A is in the range of 75.0 and 1000.0, preferably where the ratio Zr B / Zr A is in the range of 100.0 and 600.0, more preferably where the ratio Zr B / Zr A is in the range of 150.0 and 400.0.

[0109] A particular preferred embodiment relates to a positive electrode active material according to the present invention,

[0110] · where the ratio Si B / Si A is in the range of 300.0 and 400.0, and

[0111] · where the ratio Zr B / Zr A is in the range of 275.0 and 350.0.

[0112] As will be understood by those skilled in the art, the defined ratio Zr B / Zr A and Si B / Si A mean that the positive electrode active material of the present invention has an enriched amount of Zr and Si in the surface layer of the positive electrode active material. 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 Zr and Si. For example, but not limited to the present invention, the compound of Si and Zr present in the surface layer of the positive electrode active material is Li2Si 0.5 Zr 0.5 O3.

[0113] In the context of the present invention, the positive electrode active material may include a third surface layer comprising D, where D is at least one element selected from the group consisting of: Al, B, Ba, Ca, Ce, Cr, Fe, La, Mg, Mo, Nb, S, Sr, Ti, V, W, Y, and Zn; preferably Al, B, Ti, Cr, Nb, S, Y, and W; more preferably Al, B, Ti, Nb, and W, where the surface layer of Zr and Si may be located on the third surface layer and / or the third surface layer may be located on the surface layer of Zr and Si and / or the positive electrode active layer may include a mixed surface layer comprising the surface layer of Zr and Si and the third surface layer.

[0114] A particular preferred embodiment relates to a positive electrode active material according to the present invention,

[0115] · wherein the ratio of Si B / Si A is in the range of 100.0 and 1000.0, preferably wherein the ratio of Si B / Si A is in the range of 200.0 and 600.0, more preferably wherein the ratio of Si B / Si A is in the range of 250.0 and 400.0; and

[0116] · the positive electrode active material has a carbon content in the range of 0.020 wt% and 0.070 wt% of the total weight of the positive electrode active material, preferably the carbon content is in the range of 0.022 wt% and 0.060 wt% of the total weight of the positive electrode active material, more preferably the carbon content is in the range of 0.025 wt% and 0.050 wt% of the total weight of the positive electrode active material.

[0117] A particular preferred embodiment relates to a positive electrode active material according to the present invention,

[0118] · wherein the ratio of Zr B / Zr A is in the range of 75.0 and 1000.0, preferably wherein the ratio of Zr B / Zr A is in the range of 100.0 and 600.0, more preferably wherein the ratio of Zr B / Zr A is in the range of 150.0 and 400.0; and

[0119] · The positive electrode active material has a carbon content in the range of 0.020% by weight and 0.070% by weight of the total weight of the positive electrode active material, preferably the carbon content is in the range of 0.022% by weight and 0.060% by weight of the total weight of the positive electrode active material, more preferably the carbon content is in the range of 0.025% by weight and 0.050% by weight of the total weight of the positive electrode active material.

[0120] A particularly more preferred embodiment relates to a positive electrode active material according to the present invention,

[0121] · wherein the ratio of Si B / Si A is in the range of 100.0 and 1000.0, preferably wherein the ratio of Si B / Si A is in the range of 200.0 and 600.0, more preferably wherein the ratio of Si B / Si A is in the range of 250.0 and 400.0; and

[0122] · wherein the ratio of Zr B / Zr A is in the range of 75.0 and 1000.0, preferably wherein the ratio of Zr B / Zr A is in the range of 100.0 and 600.0, more preferably wherein the ratio of Zr B / Zr A is in the range of 150.0 and 400.0; and

[0123] · The positive electrode active material has a carbon content in the range of 0.020% by weight and 0.070% by weight of the total weight of the positive electrode active material, preferably the carbon content is in the range of 0.022% by weight and 0.060% by weight of the total weight of the positive electrode active material, more preferably the carbon content is in the range of 0.025% by weight and 0.050% by weight of the total weight of the positive electrode active material.

[0124] A preferred embodiment of the present invention relates to a positive electrode active material according to the present invention, the positive electrode active material having an Si content of Si B , wherein Si B is expressed as the ratio of the mole fraction of Si to the sum of the mole fractions of Ni, Mn, Co, Si and Zr, as measured by XPS analysis, wherein Si B > 0.25, preferably Si B > 0.5, more preferably Si B > 0.75. A preferred embodiment of the present invention relates to a positive electrode active material according to the present invention, wherein Si B< 5.0, preferably Si B < 2.0, more preferably Si B < 1.0. A preferred embodiment of the present invention relates to a positive electrode active material according to the present invention, wherein Si B is in the range of 0.25 and 5.0, preferably Si B is in the range of 0.5 and 2.0, more preferably Si B is in the range of 0.75 and 1.0.

[0125] A preferred embodiment relates to a positive electrode active material according to the present invention, wherein the positive electrode active material has a Zr content Zr B , wherein Zr B is expressed as a ratio of the mole fraction of Zr to the sum of the mole fractions of Ni, Mn, Co, Si, and Zr, as measured by XPS analysis, wherein Zr B > 0.25, preferably Zr B > 0.4, more preferably Zr B > 0.5. A preferred embodiment relates to a positive electrode active material according to the present invention, wherein Zr B < 2.0, preferably Zr B < 0.9, more preferably Zr B < 0.8. A preferred embodiment relates to a positive electrode active material according to the present invention, wherein Zr B is in the range of 0.25 and 2.0, preferably Zr B is in the range of 0.4 and 0.9, more preferably Zr B is in the range of 0.5 and 0.8.

[0126] A specific preferred embodiment relates to a positive electrode active material according to the present invention,

[0127] · wherein Si B is in the range of 0.25 and 5.0, preferably Si B is in the range of 0.5 and 2.0, more preferably Si B is in the range of 0.75 and 1.0, and

[0128] · wherein the content b of Zr relative to M' is b = 0.0 mol%.

[0129] Morphology

[0130] In certain preferred embodiments, the positive electrode active material of the present invention comprises single crystal particles. In the context of the present invention, as observed by scanning electron microscopy (SEM) or transmission electron microscopy (TEM), preferably by observing the grain boundaries of the particles, if the particles are composed of only one grain or at most five grains, preferably at most three grains, the particles are considered single crystals. A grain boundary is defined as the interface between two grains in a particle, preferably where the atomic planes of the two grains are arranged in different orientations and meet as a crystal discontinuity plane.

[0131] A particular more preferred embodiment relates to a positive electrode active material according to the present invention,

[0132] · the positive electrode active material comprises single crystal particles, and

[0133] · wherein the ratio Si B / Si A is in the range of 100.0 and 1000.0, preferably wherein the ratio Si B / Si A is in the range of 200.0 and 600.0, more preferably wherein the ratio Si B / Si A is in the range of 250.0 and 400.0.

[0134] A particular more preferred embodiment relates to a positive electrode active material according to the present invention,

[0135] · the positive electrode active material comprises single crystal particles, and

[0136] · wherein the ratio Zr B / Zr A is in the range of 75.0 and 1000.0, preferably wherein the ratio Zr B / Zr A is in the range of 100.0 and 600.0, more preferably wherein the ratio Zr B / Zr A is in the range of 150.0 and 400.0.

[0137] A particular more preferred embodiment relates to a positive electrode active material according to the present invention,

[0138] · the positive electrode active material comprises single crystal particles, and

[0139] · The positive electrode active material has a carbon content in the range of 0.020% by weight and 0.070% by weight of the total weight of the positive electrode active material, preferably the carbon content is in the range of 0.022% by weight and 0.060% by weight of the total weight of the positive electrode active material, more preferably the carbon content is in the range of 0.025% by weight and 0.050% by weight of the total weight of the positive electrode active material.

[0140] A particular more preferred embodiment relates to a positive electrode active material according to the present invention,

[0141] · The positive electrode active material comprises single crystal particles,

[0142] · Wherein the ratio of Si B / Si A is in the range of 100.0 and 1000.0, preferably wherein the ratio of Si B / Si A is in the range of 200.0 and 600.0, more preferably wherein the ratio of Si B / Si A is in the range of 250.0 and 400.0, and

[0143] · Wherein the ratio of Zr B / Zr A is in the range of 75.0 and 1000.0, preferably wherein the ratio of Zr B / Zr A is in the range of 100.0 and 600.0, more preferably wherein the ratio of Zr B / Zr A is in the range of 150.0 and 400.0.

[0144] A particular more preferred embodiment relates to a positive electrode active material according to the present invention,

[0145] · The positive electrode active material comprises single crystal particles,

[0146] · Wherein the ratio of Si B / Si A is in the range of 100.0 and 1000.0, preferably wherein the ratio of Si B / Si A is in the range of 200.0 and 600.0, more preferably wherein the ratio of Si B / Si A is in the range of 250.0 and 400.0,

[0147] · Wherein the ratio of Zr B / Zr A is in the range of 75.0 and 1000.0, preferably wherein the ratio of Zr B / Zr A In the range of 100.0 and 600.0, more preferably where the ratio Zr B / Zr A is in the range of 150.0 and 400.0, and

[0148] · The positive electrode active material has a carbon content in the range of 0.020% by weight and 0.070% by weight of the total weight of the positive electrode active material, preferably the carbon content is in the range of 0.022% by weight and 0.060% by weight of the total weight of the positive electrode active material, more preferably the carbon content is in the range of 0.025% by weight and 0.050% by weight of the total weight of the positive electrode active material.

[0149] As understood by those skilled in the art, the single crystal particles have the content Si A 、Si B 、Zr A and / or Zr B and their corresponding ratios.

[0150] In certain preferred embodiments of the present invention and in the context of the present invention, the single crystal particles as defined herein are integral particles. As understood by those skilled in the art, in these certain preferred embodiments, all embodiments related to the single crystal particles are equally applicable to the integral particles as defined in the present invention.

[0151] In certain preferred embodiments, the present invention provides a positive electrode active material according to the present invention, wherein the positive electrode active material is a powder comprising single particles and / or secondary particles, wherein as observed in the SEM image, each single particle consists of only one primary particle, and each secondary particle consists of at least two primary particles and at most twenty primary particles.

[0152] Preferably, at least 30% of the particles constituting the powder observed in the SEM image, more preferably at least 50% of the particles 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 10,000 μm 2 ).

[0153] The particles in the image should be evenly distributed to avoid overlap between the particles. This can be achieved by pouring a small amount of powder sample into the adhesive attached to the SEM sample holder and blowing air to remove the excess powder.

[0154] In the context of the present invention, primary particles are distinguished in SEM images by observing the grain boundaries between the primary particles. A grain boundary is defined as the interface between two primary particles, preferably where the atomic planes of the two primary particles are arranged in different orientations and meet as a crystal discontinuity plane.

[0155] As understood by those skilled in the art, 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 of the polycrystalline particles, as observed in the SEM image, is composed of more than 20 primary particles, preferably 50 or more primary particles, more preferably 100 or more primary particles.

[0156] Preferably at least 30% of the particles, more preferably at least 50% of the particles, constituting the powder as observed in the SEM image 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 10,000 μm 2 ). 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 the powder sample into an adhesive attached to the SEM sample holder and blowing air to remove the excess powder.

[0157] In certain preferred embodiments, the positive electrode active material of the present invention comprises polycrystalline particles. As 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 the grain boundaries using appropriate microscopy techniques such as scanning electron microscopy (SEM). Under post-treatment steps such as heat treatment steps, the single crystal particles coalesce into polycrystalline particles.

[0158] A particular more preferred embodiment relates to a positive electrode active material according to the present invention,

[0159] · the positive electrode active material comprises polycrystalline particles, and

[0160] · wherein the ratio Si B / Si A is in the range of 100.0 and 1000.0, preferably wherein the ratio Si B / Si A is in the range of 200.0 and 600.0, more preferably wherein the ratio Si B / Si A is in the range of 250.0 and 400.0.

[0161] A specific more preferred embodiment relates to a positive electrode active material according to the present invention,

[0162] · The positive electrode active material comprises polycrystalline grains, and

[0163] · wherein the ratio Zr B / Zr A is in the range of 75.0 and 1000.0, preferably wherein the ratio Zr B / Zr A is in the range of 100.0 and 600.0, more preferably wherein the ratio Zr B / Zr A is in the range of 150.0 and 400.0.

[0164] A specific more preferred embodiment relates to a positive electrode active material according to the present invention,

[0165] · The positive electrode active material comprises polycrystalline grains, and

[0166] · The positive electrode active material has a carbon content in the range of 0.020 wt% and 0.070 wt% of the total weight of the positive electrode active material, preferably a carbon content in the range of 0.022 wt% and 0.060 wt% of the total weight of the positive electrode active material, more preferably a carbon content in the range of 0.025 wt% and 0.050 wt% of the total weight of the positive electrode active material.

[0167] A specific more preferred embodiment relates to a positive electrode active material according to the present invention,

[0168] · The positive electrode active material comprises polycrystalline grains,

[0169] · wherein the ratio Si B / Si A is in the range of 100.0 and 1000.0, preferably wherein the ratio Si B / Si A is in the range of 200.0 and 600.0, more preferably wherein the ratio Si B / Si A is in the range of 250.0 and 400.0,

[0170] · wherein the ratio Zr B / Zr A is in the range of 75.0 and 1000.0, preferably wherein the ratio Zr B / Zr A is in the range of 100.0 and 600.0, more preferably wherein the ratio Zr B / ZrA in the range of 150.0 and 400.0.

[0171] A particular more preferred embodiment relates to a positive electrode active material according to the present invention,

[0172] · The positive electrode active material comprises polycrystalline grains,

[0173] · wherein the ratio Si B / Si A is in the range of 100.0 and 1000.0, preferably wherein the ratio Si B / Si A is in the range of 200.0 and 600.0, more preferably wherein the ratio Si B / Si A is in the range of 250.0 and 400.0,

[0174] · wherein the ratio Zr B / Zr A is in the range of 75.0 and 1000.0, preferably wherein the ratio Zr B / Zr A is in the range of 100.0 and 600.0, more preferably wherein the ratio Zr B / Zr A is in the range of 150.0 and 400.0, and

[0175] · The positive electrode active material has a carbon content in the range of 0.020 wt% and 0.070 wt% of the total weight of the positive electrode active material, preferably a carbon content in the range of 0.022 wt% and 0.060 wt% of the total weight of the positive electrode active material, more preferably a carbon content in the range of 0.025 wt% and 0.050 wt% of the total weight of the positive electrode active material.

[0176] A particular preferred embodiment relates to a positive electrode active material according to the present invention,

[0177] · The positive electrode active material comprises polycrystalline grains,

[0178] · wherein Si B is in the range of 0.25 and 5.0, preferably Si B is in the range of 0.5 and 2.0, more preferably Si B is in the range of 0.75 and 1.0, and

[0179] · wherein the content b of Zr relative to M' is b = 0.0 mol%.

[0180] As will be understood by those skilled in the art, the polycrystalline grains have the content Si A, Si B , Zr A and / or Zr B and their corresponding ratios.

[0181] In certain preferred embodiments of the present invention and in the context of the present invention, the polycrystalline particles as defined herein are secondary particles. As will be understood by those skilled in the art, in these certain preferred embodiments, all embodiments related to the polycrystalline particles equally apply to the secondary particles as defined in the present invention.

[0182] Certain preferred embodiments relate to the positive electrode active material of the present invention, the positive electrode active material comprising single crystal particles having a primary particle median D50 value of less than 10 mm, preferably less than 8 mm, more preferably less than 5 mm. Certain preferred embodiments relate to the positive electrode active material of the present invention, the positive electrode active material comprising single crystal particles having a primary particle median D50 value of greater than 1 mm, preferably greater than 2 mm, more preferably greater than 3 mm. Certain preferred embodiments relate to the positive electrode active material of the present invention, the positive electrode active material comprising single crystal particles having a primary particle median D50 value between 1 μm and 10 mm, preferably between 2 μm and 8 mm, more preferably between 3 μm and 5 mm. 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. Preferably, D50 is defined as the volume average particle size, more preferably the particle size at 50% of the cumulative volume % distribution obtained from a Malvern Mastersizer 3000 with Hydro MV measurement. For example, but not limited to the present invention, the particle median D50 can be measured using a Malvern Mastersizer 3000. Certain preferred embodiments relate to the positive electrode active material of the present invention, the positive electrode active material comprising polycrystalline particles having a secondary particle median D50 value of less than 20 mm, preferably less than 15 mm, more preferably less than 12 mm. Certain preferred embodiments relate to the positive electrode active material of the present invention, the positive electrode active material comprising polycrystalline particles having a secondary particle median D50 value of greater than 1 mm, preferably greater than 3 mm, more preferably greater than 5 mm. Certain preferred embodiments relate to the positive electrode active material of the present invention, the positive electrode active material comprising polycrystalline particles having a secondary particle median D50 value between 1 μm and 20 mm, preferably between 3 μm and 15 mm, more preferably between 5 μm and 12 mm. 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. Preferably, D50 is defined as the volume average particle size, more preferably the particle size at 50% of the cumulative volume % distribution obtained from a Malvern Mastersizer 3000. For example, but not limited to the present invention, the particle median D50 can be measured using a Malvern Mastersizer 3000.

[0183] In another aspect, the present invention provides a secondary particle-based positive electrode active material for a solid-state storage battery, the secondary particle-based positive electrode active material comprising Li, M' and O, wherein M' comprises:

[0184] - Ni at a content of x, wherein 50.0 mol% ≤ x ≤ 95.0 mol% relative to M',

[0185] - Mn with a content of y, where 0.0 mol% ≤ y ≤ 30.0 mol% relative to M',

[0186] - Co with a content of z, where 0.0 mol% ≤ z ≤ 30.0 mol% relative to M',

[0187] - Si with a content of a, where 0.01 mol% ≤ a ≤ 1.5 mol% relative to M',

[0188] - Zr with a content of b, where 0.0 mol% ≤ b ≤ 1.5 mol% relative to M',

[0189] - D with a content of d, where D is an element other than Li, Ni, Mn, Co, Si, Zr, and O; where 0.0 mol% ≤ d ≤ 2.0 mol% relative to M', and,

[0190] - where x, y, z, a, b, and d are measured by ICP - OES,

[0191] - where x + y + z + a + b + d = 100.0 mol%,

[0192] where the positive electrode active material has a Si content Si A , the Si A is defined as a / (x + y + z + a + b), where the positive electrode active material has a Si content Si B , where Si B is expressed as the ratio of the mole fraction of Si to the sum of the mole fractions of Ni, Mn, Co, Si, and Zr, as measured by XPS analysis, where the ratio Si B / Si A > 50.0.

[0193] In a highly preferred embodiment of the secondary particle - based positive electrode active material, all embodiments of the positive electrode active material according to the first aspect of the present invention are applicable with the necessary modifications to the secondary particle - based positive electrode active material. For example, the various embodiments regarding the identification and amounts of Li, M', Si B , Si A , Zr A , and Zr B explained herein in the context of the positive electrode active material are equally applicable to the secondary particle - based positive electrode active material.

[0194] In another aspect, the present invention provides a single - crystal particle - based positive electrode active material for a solid - state storage battery, the single - crystal particle - based positive electrode active material comprising Li, M', and O, where M' includes:

[0195] - Ni with a content of x, where 50.0 mol% ≤ x ≤ 95.0 mol% relative to M',

[0196] - Mn with a content of y, where 0.0 mol% ≤ y ≤ 30.0 mol% relative to M',

[0197] - Co with a content of z, where 0.0 mol% ≤ z ≤ 30.0 mol% relative to M',

[0198] - Si with a content of a, where 0.01 mol% ≤ a ≤ 1.5 mol% relative to M',

[0199] - Zr with a content of b, where 0.0 mol% ≤ b ≤ 1.5 mol% relative to M',

[0200] - D with a content of d, where D is an element other than Li, Ni, Mn, Co, Si, Zr, and O; where 0.0 mol% ≤ d ≤ 2.0 mol% relative to M', and,

[0201] - where x, y, z, a, b, and d are measured by ICP - OES,

[0202] - where x + y + z + a + b + d = 100.0 mol%,

[0203] where the positive electrode active material has an Si content Si A where the Si A is defined as a / (x + y + z + a + b), where the positive electrode active material has an Si content Si B where Si B is expressed as the ratio of the mole fraction of Si to the sum of the mole fractions of Ni, Mn, Co, Si, and Zr, as measured by XPS analysis, where the ratio Si B / Si A > 50.0.

[0204] In a highly preferred embodiment of the single - crystal particle - based positive electrode active material, all embodiments of the positive electrode active material according to the first aspect of the present invention are applicable with the necessary modifications to the single - crystal particle - based positive electrode active material. For example, the various embodiments regarding the identification and amounts of Li, M', Si B Si A Zr A Zr B explained herein in the context of the positive electrode active material are equally applicable to the single - crystal particle - based positive electrode active material.

[0205] Method

[0206] In a second aspect, the present invention provides a method for manufacturing a positive electrode active material, wherein the method comprises:

[0207] - preparing a slurry comprising a lithium transition metal-based oxide compound, a Li source, and an alcohol,

[0208] - mixing the slurry with a Si source and optionally a Zr source, preferably mixing the slurry with a Si source and a Zr source, and

[0209] - heating the mixture at a temperature between 250 °C and below 500 °C for a time of 1 hour to 20 hours to obtain the positive electrode active material.

[0210] 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 the positive electrode active material according to the first aspect of the present invention. As will be understood by those skilled in the art, if the method for manufacturing the positive electrode active material of the present invention results in the positive electrode material according to the first aspect of the present invention, then all embodiments relating to the positive electrode active material according to the first aspect of the present invention are applicable with the necessary modifications to the method for manufacturing the positive electrode active material according to the first aspect of the present invention. For example, the various embodiments relating to the identification and amounts of Li, M', Si B 、Si A 、Zr A and Zr B explained herein in the context of the positive electrode active material are equally applicable to the method for preparing the positive electrode active material.

[0211] In a preferred embodiment, the Li source is metallic lithium or a lithium salt, preferably a lithium salt such as LiOH.

[0212] In a preferred embodiment of the method, the lithium transition metal-based oxide compound comprises Li, M", and O, where M" includes Ni, Mn, Co, and D, and D is at least one element from the group consisting of: Al, B, Ba, Ca, Ce, Cr, Fe, La, Mg, Mo, Nb, S, Sr, Ti, V, W, Y, and Zn; preferably Al, B, Ti, Cr, Nb, S, Y, and W; more preferably Al, B, Ti, Nb, and W. Preferably, the lithium transition metal-based oxide used is generally also prepared according to a lithiation process, which is a process of heating a mixture of a transition metal oxide precursor and an additional lithium source at a temperature preferably of at least 500 °C and at most 1000 °C. Generally, the transition metal precursor is prepared by co-precipitation of one or more transition metal sources (such as salts of elements Ni, Mn, and / or Co, preferably sulfates or nitrates, more preferably sulfates) in the presence of a basic compound (such as a basic hydroxide, for example sodium hydroxide and / or ammonia). Preferably, the additional lithium source is metallic lithium or a lithium salt, preferably a lithium salt such as LiOH.

[0213] In a preferred embodiment, the slurry further comprises water. Preferably, the amount of water in the slurry is between 0.5 mol% and 25.0 mol% relative to the metal content in the lithium transition metal oxide compound, preferably between 0.7 mol% and 10.0 mol% relative to the metal content in the lithium transition metal oxide compound, more preferably between 1 mol% and 5 mol%.

[0214] In a preferred embodiment of the method, the Zr source is a zirconium alkoxide, preferably zirconium ethoxide, zirconium propoxide, or zirconium butoxide, more preferably zirconium propoxide, such as zirconium(IV) propoxide. In a preferred embodiment, the zirconium alkoxide is mixed with the mixture as a solid. Alternatively, and more preferably, the zirconium alkoxide is mixed with the slurry as a solution, where the solution comprises the zirconium alkoxide and an additional alcohol, and the alkoxide group is the conjugate base of the additional alcohol. For example, the zirconium alkoxide is zirconium(IV) propoxide dissolved in propanol. Generally, the solution comprises 50 wt% to 90 wt% of the zirconium alkoxide based on the total weight of the solution. Examples of such solutions are 70 wt% zirconium propoxide in 1-propanol or 80 wt% zirconium butoxide in 1-butanol. Preferably, the alcohol solvent is methanol, ethanol, propanol, or butanol, preferably ethanol.

[0215] In a preferred embodiment, the amount of Zr present in the Zr source in the slurry is between 0.0 mol% and 1.0 mol% relative to the metal content in the lithium transition metal-based oxide compound, preferably between 0.05 mol% and 0.75 mol% relative to the metal content in the lithium transition metal-based oxide compound, more preferably between 0.1 mol% and 0.5 mol%.

[0216] In a preferred embodiment of the method, the Si source is a silanolate, an alkylalkoxysilane or a polysiloxane, preferably a silanolate.

[0217] In a more highly preferred embodiment, the Si source is a silanolate, preferably SiOR 1 R 2 R 3 R 4 , where R 1 , R 2 , R 3 and R 4 are independently selected from H and C1-C8 alkyl or alkenyl groups optionally substituted with halides, preferably C1-C4 alkyl groups, more preferably C1-C2 alkyl groups. In a more preferred embodiment of the method, the Si source is a silanolate, i.e., SiOR4 5 , where R 5 is a C1-C8 alkyl or alkenyl group optionally substituted with halides, preferably C1-C4 alkyl groups, more preferably C1-C2 alkyl groups. In a highly preferred embodiment, the Si source is tetraethyl orthosilicate.

[0218] In a preferred embodiment, the Si source is an alkylalkoxysilane, more preferably R 6 a (R 7 O) b Si, where a = 1, 2 or 3, b = 1, 2 or 3, a + b = 4, and R 6 and R 7 are selected from the group consisting of: H and C1-C8 alkyl or alkenyl groups optionally substituted with halides, preferably C1-C4 alkyl groups, more preferably C1-C2 alkyl groups; more preferably R 6 and R 7 are the same alkyl groups selected from the group consisting of: C1-C8 alkyl or alkenyl groups optionally substituted with halides, preferably C1-C4 alkyl groups, more preferably C1-C2 alkyl groups; most preferably the Si source is methyltrimethoxysilane.

[0219] In a preferred embodiment, the Si source is a polysiloxane, preferably a polydialkylsiloxane, where the alkyl groups are selected from C1-C8 alkyl or alkenyl groups optionally substituted with halides, preferably C1-C4 alkyl groups, more preferably C1-C2 alkyl groups, more preferably polydimethylsiloxane. In a highly preferred embodiment, the Si source is a polysiloxane, the polysiloxane being a hydroxyl-terminated polydimethylsiloxane or a trimethylsilyloxy-terminated polydimethylsiloxane, preferably a hydroxyl-terminated polydimethylsiloxane. The present invention is not limited to having a specific number average molecular weight M nSpecific polydimethylsiloxanes. Such polymers with many different number-average molecular weights are commercially available. Preferably, the hydroxyl-terminated polydimethylsiloxane or trimethylsiloxysiloxane-terminated polydimethylsiloxane has a number-average molecular weight M between 200 g / mol and 1,000,000 g / mol, preferably between 300 g / mol and 150,000 g / mol, and most preferably between 400 g / mol and 10,000 g / mol, such as about 410 g / mol or 4200 g / mol. n .

[0220] A preferred embodiment of the method is to heat the mixture in an oxidizing atmosphere. Preferably, the oxidizing atmosphere includes oxygen, such as air, or consists of oxygen.

[0221] A preferred embodiment of the method is to heat the mixture at a temperature of at least 275 °C, preferably at least 300 °C, more preferably at least 325 °C. A preferred embodiment of the method is to heat the mixture at a temperature of at most 450 °C, preferably at most 400 °C, more preferably at most 375 °C. A preferred embodiment of the method is to heat the mixture between 275 °C and 450 °C, preferably between 300 °C and 400 °C, more preferably between 325 °C and 375 °C.

[0222] A preferred embodiment of the method is to heat the mixture for at least 2 hours, preferably at least 3 hours, more preferably at least 4 hours. A preferred embodiment of the method is to heat the mixture for at most 15 hours, preferably at most 10 hours, more preferably at most 7 hours. A preferred embodiment of the method is to heat the mixture for 2 hours to 15 hours, preferably 3 hours to 10 hours, more preferably 4 hours to 7 hours.

[0223] A preferred embodiment of the method is

[0224] · to heat the mixture at a temperature between 275 °C and 450 °C, preferably between 300 °C and 400 °C, more preferably between 325 °C and 375 °C; and

[0225] · to heat the mixture for 2 hours to 15 hours, preferably 3 hours to 10 hours, more preferably 4 hours to 7 hours.

[0226] In a more preferred embodiment, the heating is carried out in a furnace.

[0227] Certain preferred embodiments of the method include an additional step of drying the mixture before heating the mixture. Preferably, the drying is carried out in a vacuum, under vacuum heating, or under a constant stream of N2 for at least 4 hours and at most 20 hours.

[0228] In certain preferred embodiments of the method, the slurry comprises water as defined herein, and the method includes an additional step of filtering and drying the mixture before heating the mixture. Preferably, the drying is carried out under vacuum, vacuum heating or under a constant stream of N2 for at least 4 hours and up to 20 hours. As will be understood by those skilled in the art, filtering the mixture is achieved by conventional filtering techniques known in the art.

[0229] The method characterizes the product

[0230] 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. 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 applicable with the necessary modifications to the positive electrode activity obtainable by the method according to the present invention. For example, the various embodiments relating to the identification and amounts of Li, M', Si A , Si B , Zr A , Zr B , Zr

[0231] Storage battery

[0232] In a fourth aspect, the present invention relates to a storage 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.

[0233] In a preferred embodiment, the storage battery is a solid-state storage battery. Preferably, the solid-state storage battery comprises a sulfide-based electrolyte. Preferably, the electrolyte is a sulfide-based solid electrolyte, and more preferably, the electrolyte comprises Li, P, and S. Generally, the following sulfur-containing compounds of Li6PS5X can be appropriately used, where X is F, Cl, Br, or I; preferably X is Cl or Br, thio-LISICON (Li 3.25 Ge 0.25 P 0.75 S4), Li2S-P2S5-LiCl, Li2S-SiS2, LiI-Li2S-SiS2, Li2S-P2S5-LiCl, Li2S-SiS2, LiI-Li2S-SiS2, LiI-Li2S-P2S5, LiI-Li2SP2O5, LiI-Li3PO4-P2S5, Li2S-P2S5, Li3PS4, Li7P3S 11, LiI-Li2S-B2S3, Li3PO4-Li2S-SiS2, Li3PO4-Li2S-SiS2, Li3PO4-Li2S-SiS2, Li 10 GeP2S 12 , Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 and / or Li7P3S 11 . In a highly preferred embodiment, the storage battery is a sulfide solid-state storage battery.

[0234] Preferably, the solid-state storage battery further includes an anode, and the anode contains an anode active material. Suitable electrochemically active anode materials are those known in the art. For example, the anode may include graphite carbon, metallic lithium, or a lithium-containing metal alloy such as a Li-In alloy as the anode active material.

[0235] In a preferred embodiment, the storage battery according to the present invention has a first discharge capacity of at least 175 mAh / g, more preferably at least 180 mAh / g, more preferably at least 185 mAh / g, and most preferably at least 190 mAh / g. As understood by those skilled in the art, the first discharge capacity (DQ1) is measured at a C-rate of 0.1C in a constant current mode (CC) within the following voltage ranges: 4.3V to 2.5V (Li / Li + ) or 3.7V to 1.9V (InLi / Li + ).

[0236] In a preferred embodiment, the storage battery according to the present invention has an efficiency of at least 88%, preferably at least 90%, more preferably at least 92%. As understood by those skilled in the art, the efficiency of the storage battery is determined, where the initial charge capacity (CQ1) and the discharge capacity (DQ1) are measured at a C-rate of 0.1C in a constant current mode (CC) within the voltage range of 4.3V to 2.5V (Li / Li+) or 3.7V to 1.9V (In-Li / Li+). The efficiency (%) of the reversible capacity is obtained according to the following equation:

[0237]

[0238] Preferably, the 1C current is defined as 160 mA / g.

[0239] Use

[0240] 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 storage battery.

[0241] A preferred embodiment is the use of the positive electrode active material in a storage battery, preferably a solid-state storage battery, more preferably a sulfide solid-state storage battery, to improve the efficiency of the storage battery and / or increase the first discharge capacity of the storage battery.

[0242] In a sixth aspect, the present invention relates to the use of a storage 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 a hybrid electric vehicle, preferably in an electric vehicle or a hybrid electric vehicle.

[0243] Examples

[0244] Experimental analysis used in the examples

[0245] The following analysis methods were used in the examples.

[0246] A) Inductively coupled plasma optical emission spectrometry (ICP-OES) measurement

[0247] The amounts of Li, Ni, Co, Mn, Si, and Zr in the positive electrode active material powder were measured by inductively coupled plasma-optical emission spectrometry (ICP-OES) using an Agillent ICP 720-ES (Agilent Technologies). 2 g of the powder sample was dissolved in 10 mL of high-purity hydrochloric acid (HCl at least 37 wt% relative to the total weight of the solution) in a conical flask. The flask was covered with glass and heated on a hot plate at 380 °C until the precursor was completely dissolved. After cooling to room temperature, the solution in the conical flask was poured into a 250 mL volumetric flask. Then, the volumetric flask was filled with deionized water up to the 250 mL graduation mark and then mixed well. Another suitable solvent can be used to fully dissolve the positive electrode active material powder sample.

[0248] B) X-ray photoelectron spectroscopy (XPS) measurement

[0249] X-ray photoelectron spectroscopy (XPS) was used to analyze the surface of the positive electrode active material. In XPS measurement, the signal was obtained from the top few nanometers (e.g., 1 nm to 10 nm) (i.e., the surface layer) of the sample. Therefore, all elements measured by XPS were contained in the surface layer.

[0250] For the surface analysis of the positive electrode active material powder particles, XPS measurements were carried out using a Thermo K-α+ spectrometer. Monochromatic AlKα radiation (hν = 1486.6 eV) was used, the spot size was 400 μm, and the measurement angle was 45°. A wide survey scan was performed at a pass energy of 200 eV to identify the elements present on the surface. After data collection, the C1s peak with the maximum intensity (or center) at a binding energy of 284.8 eV was used as the calibration peak position. Subsequently, precise narrow scans were performed at 50 eV, and at least 10 scans were carried out for each identified element to determine the precise surface composition.

[0251] Curve fitting was carried out using Shirley-type background processing and Scofield sensitivity factors through CasaXPS version 2.3.19PR1.0 (Casa Software). The fitting parameters are shown in Table 2a. The line shape GL(30) is the Gaussian / Lorentz product formula, where 70% is the Gaussian line and 30% is the Lorentz line. LA(α,β,m) is an asymmetric line shape, where α and β define the peak tail extension and m defines the width.

[0252] Table 1a. XPS fitting parameters for Ni2p, Mn2p, Co2p, Si2p, and Zr3d.

[0253]

[0254] For the Mn, Co, and Zr peaks, constraints were set for each defined peak according to Table 1b.

[0255] Table 1b. XPS fitting constraints for Mn2p, Co2p, and Zr3d.

[0256]

[0257] The surface content of Si and the surface content of Zr determined by XPS are expressed as the mole fraction of Si and the mole fraction of Zr in the surface layer of the particles divided by the total content of Ni, Co, Mn, Si, and Zr in the surface layer. The calculation method is as follows:

[0258]

[0259]

[0260] After fitting, the information on the XPS peak positions can be easily obtained in the area and component report specifications. The XPS spectra of Si and Zr for EX1.1 are as Figure 1 shown.

[0261] C) Carbon analysis

[0262] The carbon content of the positive electrode active material powder was measured using a Horiba Emia-Expert carbon / sulfur analyzer. 1 g of the positive electrode active material powder was placed in a ceramic crucible in a high-frequency induction furnace. 1.5 g of tungsten and 0.2 g of tin were added to the crucible as accelerators. The powder was heated at a programmable temperature, and then the gas generated during combustion was analyzed by an infrared detector. The analysis of CO2 and CO determined the carbon concentration.

[0263] D) Sulfide solid-state rechargeable battery testing

[0264] D-1) Preparation of sulfide solid-state rechargeable battery

[0265] Positive electrode preparation:

[0266] For the preparation of the positive electrode, a slurry containing positive electrode active material powder, Li-P-S-based solid electrolyte, carbon (Super-P, Timcal), and binder (RC-10, Arkema) (in a formulation of 64.0:30.0:3.0:3.0 by weight) in butyl acetate solvent was mixed in a glove box filled with argon. The slurry was cast on one side of an aluminum foil, and then the slurry-coated foil was dried in a vacuum oven to obtain the positive electrode. The resulting positive electrode was punched with a diameter of 10 nm, with an active material loading of approximately 4 mg / cm 2 .

[0267] Negative electrode preparation:

[0268] For the preparation of the negative electrode, a Li foil (3 mm in diameter, 100 μm thick) was placed at the top center of an In foil (10 nm in diameter, 100 μm thick), and pressed to form a Li-In alloy negative electrode.

[0269] Separator preparation:

[0270] To prepare a separator with solid electrolyte function, the Li-P-S-based solid electrolyte was pressed into a tablet at a pressure of 250 MPa to obtain a tablet with a thickness of 100 μm.

[0271] Battery assembly:

[0272] The sulfide solid-state rechargeable battery was assembled in a glove box filled with argon, in the order from bottom to top: positive electrode containing an Al current collector (coated part on top) - separator - negative electrode (Li side on top) - Cu current collector. The stacked components were pressed together at a pressure of 250 MPa and placed in an external cage to prevent exposure to air.

[0273] D-2) Test method

[0274] The test method is the conventional "constant cut-off voltage" test. The conventional battery tests in the present invention are carried out according to the scheme shown in Table 2. Each battery is cycled at 60 °C using a Toscat-3100 computer-controlled constant current cycling station (from Toyo).

[0275] The scheme is defined using a 1C current of 160 mA / g. The initial charge capacity (CQ1) and discharge capacity (DQ1) are measured at a C rate of 0.1C in constant current mode (CC) within the voltage range of 4.3 V to 2.5 V (Li / Li + ) or 3.7 V to 1.9 V (In-Li / Li + ). The efficiency (%) of the reversible capacity is obtained according to the following equation:

[0276]

[0277] The present invention is further illustrated in the following examples.

[0278] Comparative Example 1

[0279] The positive electrode active material CEX1 is obtained through the following steps:

[0280] 1) Preparation of the mixture: 100.00 grams of Ni 0.64 Co 0.20 Mn 0.16 (OH)2 and 26.77 grams of anhydrous LiOH are mixed evenly to obtain the mixture.

[0281] 2) First heating: The mixture prepared in step 1) is heated at 830 °C in an O2 atmosphere for 10 hours and cooled to room temperature.

[0282] 3) Preparation of the metal solution: 1.01 grams of zirconium(IV) propoxide (a 70.0 wt% solution of zirconium propoxide in n-propanol) is dissolved in 3 grams of ethanol.

[0283] 4) Preparation of the slurry: 70.00 grams of the first-heated material, 26.00 grams of ethanol, 0.19 grams of deionized water, and 0.10 grams of LiOH are mixed evenly to obtain the slurry.

[0284] 5) Preparation of the wet mixture: The metal solution prepared in step 3) and the slurry prepared in step 4) are mixed and stirred for 15 hours, and then filtered.

[0285] 6) Second heating: The wet mixture prepared in step 5) is heated at 350 °C in an O2 atmosphere at a heating rate of 5 °C / min for 5 hours. The second-heated material is cooled to room temperature, pulverized, and sieved to obtain the positive electrode active material CEX1.

[0286] Example 1.1

[0287] The positive electrode active material EX1.1 is obtained through the following steps:

[0288] 1) Prepare a mixture: Mix 100.00 g of Ni 0.64 Co 0.20 Mn 0.16 (OH)2 and 26.77 g of anhydrous LiOH evenly to obtain a mixture.

[0289] 2) First heating: Heat the mixture prepared in step 1) at 830 °C in an O2 atmosphere for 10 hours and cool it to room temperature.

[0290] 3) Prepare a metal solution: Dissolve 0.76 g of zirconium(IV) propoxide (a 70.0 wt% solution of zirconium propoxide in n-propanol) and 0.11 g of silicon tetraethanolate in 3 g of ethanol.

[0291] 4) Prepare a slurry: Mix 70.00 g of the first-heated material, 26.00 g of ethanol, 0.19 g of deionized water, and 0.10 g of LiOH evenly to obtain a slurry.

[0292] 5) Prepare a wet mixture: Mix the metal solution prepared in step 3) and the slurry prepared in step 4), stir for 15 hours, and then filter.

[0293] 6) Second heating: Heat the wet mixture prepared in step 5) at 350 °C in an O2 atmosphere at a heating rate of 5 °C / min for 5 hours. Cool the second-heated material to room temperature, crush it, and sieve it to obtain the positive electrode active material EX1.1.

[0294] Example 1.2

[0295] The positive electrode active material EX1.2 is prepared according to the same method as EX1.1, except that 0.51 g of zirconium(IV) propoxide and 0.22 g of silicon tetraethanolate are used to prepare the metal solution in step 3).

[0296] Example 1.3

[0297] The positive electrode active material EX1.3 is prepared according to the same method as EX1.1, except that 0.45 g of silicon tetraethanolate is used to prepare the metal solution in step 3).

[0298] Example 2.1

[0299] The positive electrode active material 2.1 is obtained through the following steps:

[0300] 1) Preparation of the mixture: Mix 100.00 g of Ni 0.64 Co 0.20 Mn 0.16 (OH)2 and 26.77 g of anhydrous LiOH uniformly to obtain a mixture.

[0301] 2) First heating: Heat the mixture prepared in step 1) at 830 °C in an O2 atmosphere for 10 hours and cool to room temperature.

[0302] 3) Preparation of the metal solution: Dissolve 0.51 g of zirconium(IV) propoxide (a 70.0 wt% solution of zirconium propoxide in n-propanol) and 0.22 g of silicon tetraethanolate in 3 g of ethanol.

[0303] 4) Preparation of the slurry: Mix 70.00 g of the material from the first heating, 26.00 g of ethanol, and 0.10 g of LiOH uniformly to obtain a slurry.

[0304] 5) Preparation of the second mixture: Mix the metal solution prepared in step 3) and the slurry prepared in step 4), and stir for 15 hours. Evaporate the mixed slurry to obtain the second mixture.

[0305] 6) Second heating: Heat the second mixture prepared in step 5) at 350 °C in an O2 atmosphere at a heating rate of 5 °C / min for 5 hours. Cool the material from the second heating to room temperature, crush, and screen to obtain the positive electrode active material EX2.1.

[0306] Example 2.2

[0307] The positive electrode active material EX2.2 is prepared according to the same method as EX2.1, except that 0.45 g of silicon tetraethanolate is used to prepare the metal solution in step 3).

[0308] Comparative Example 2

[0309] The positive electrode active material CEX2 is obtained through the following steps:

[0310] 1) First mixing: Mix 100.00 g of Ni 0.64 Co 0.20 Mn 0.16 (OH)2 and 26.77 g of anhydrous LiOH uniformly to obtain the first mixture.

[0311] 2) First heating: Heat the first mixture prepared in step 1) at 830 °C in an O2 atmosphere for 10 hours and cool to room temperature.

[0312] 3) Second mixing: Mix 100.00 g of the material heated for the first time and 0.19 g of SiO2 evenly to obtain a second mixture.

[0313] 4) Second heating: Heat the second mixture prepared in step 2) at 700 °C at a heating rate of 5 °C / min for 10 h until it reaches 350 °C, and then heat it at a heating rate of 2 °C / min until it reaches 700 °C. Cool the material after the second heating to room temperature, grind it, and sieve it to obtain the positive electrode active material CEX2.

[0314] Comparative Example 3.1

[0315] The positive electrode active material CEX3.1 is obtained through the following steps:

[0316] 1) First mixing: Mix 100.00 g of Ni 0.64 Co 0.20 Mn 0.16 (OH)2 and 26.77 g of anhydrous LiOH evenly to obtain a first mixture.

[0317] 2) First heating: Heat the first mixture prepared in step 1) at 830 °C in an O2 atmosphere for 10 h and then cool it to room temperature.

[0318] 3) Second mixing: Mix 100.00 g of the material heated for the first time and 0.77 g of ZrO2 evenly to obtain a second mixture.

[0319] 4) Second heating: Heat the second mixture prepared in step 2) at 850 °C for 6 h and then cool it to room temperature. Grind the cooled material and sieve it to obtain the positive electrode active material CEX3.1.

[0320] Comparative Example 3.2

[0321] The positive electrode active material CEX3.2 is prepared according to the same method as CEX3.1, except that 0.30 g of LiOH is added during the second mixing in step 3) to prepare the second mixture.

[0322] Table 3. Summary of chemical composition, Si B / Si A ratio and Zr B / Zr A and carbon content

[0323]

[0324] * Composition relative to the total molar content of Ni, Co, Mn, Si and Zr

[0325] **Si B or Zr B is the mole fraction of Si or Zr relative to the total mole content of Ni, Mn, Co, Si, and Zr obtained by XPS analysis

[0326] ***Si A or Zr A is the mole fraction of Si or Zr relative to the total mole content of Ni, Mn, Co, Si, and Zr obtained by ICP - OES analysis

[0327] ****n / a: Not available

[0328] Table 4. Summary of Electrochemical Properties

[0329]

[0330] Table 3 summarizes the chemical compositions, Si B / Si A ratio and Zr B / Zr A , and carbon content of all the examples and comparative examples. Table 4 summarizes the electrochemical properties of the examples and comparative examples, such as the first discharge capacity DQ1 and efficiency.

[0331] In Table 3, the XPS analysis results of Si (Si B ) and Zr (Zr B ) are compared with the ICP - OES results of Si (Si A ) and Zr (Zr A ) of CEX1, EX1.1, EX1.2, EX1.3, EX2.1, and EX2.2. Si B or Zr B results greater than 0 in XPS measurement indicate that the Si or Zr exists on the surface of the positive electrode active material, and the signal for XPS measurement is obtained from the top few nanometers (e.g., 1 nm to 10 nm) of the sample. On the other hand, Si A and Zr A from ICP - OES measurement are the Si content and Zr content of the whole particles. Therefore, a ratio of XPS results to ICP - OES results (such as Si B / Si A and Zr B / Zr A ) greater than 1 indicates that the Si and Zr mainly exist on the surface of the positive electrode active material. The Si B / Si A value or Zr B / Zr AThe larger the value, the more Si or Zr exists on the surface of the positive electrode active material. Figure 1 It is a representative XPS spectrum showing the Si peak and Zr peak of EX1.1.

[0332] The positive electrode active material EX1.1 contains 0.075 mol% of Si and 0.225 mol% of Zr relative to the total molar content of Ni, Mn, Co, Si, and Zr. The Si of EX1.1 B / Si A value and Zr B / Zr A values are 360.0 and 306.7, respectively, which confirms the presence of Si and Zr on the surface of the particles according to the present invention. The positive electrode active material CEX1 contains 0.30 mol% of Zr relative to the total molar content of Ni, Mn, Co, Si, and Zr, while CEX1 does not contain Si. The solid-state rechargeable battery containing EX1.1 has a DQ1 value of 190.6 mAh / g, which is greater than the DQ1 value of 174.6 mAh / g of the battery containing CEX1. In addition, the efficiency of the battery containing EX1.1 is 92.3%, while the efficiency of the battery containing CEX1 is 88.6%, indicating that the battery containing EX1.1 has improved electrochemical stability. The positive electrode active materials EX1.2 and EX2.1 contain 0.15 mol% of Si and 0.15 mol% of Zr relative to the total molar content of Ni, Mn, Co, Si, and Zr. The Si of EX1.2 and EX2.1 B / Si A values are 346.7 and 266.7, respectively, and the Zr of EX1.2 and EX2.1 B / Zr A values are 280.0 and 186.7, respectively, which confirms the presence of Si and Zr on the surfaces of EX1.2 and EX2.1 according to the present invention. The DQ1 value and efficiency of the battery containing EX1.2 are 183.7 mAh / g and 90.4%, respectively, and the DQ1 value and efficiency of the battery containing EX2.1 are 192.5 mAh / g and 90.6%, respectively. The DQ1 value and efficiency of the battery containing EX1.2 or EX2.1 are both greater than the DQ1 value and efficiency of the battery containing CEX1, indicating that the battery containing EX1.2 or EX2.1 has a higher initial capacity and improved electrochemical stability.

[0333] Both of the positive electrode active materials EX1.3 and EX2.2 contain 0.30 mol% of Si relative to the total molar content of Ni, Mn, Co, Si, and Zr. The DQ1 value of the solid-state battery containing EX1.3 is 178.3 mAh / g (greater than that of the battery containing CEX1), and the efficiency is 88.3%, similar to that of the battery containing CEX1. The DQ1 value of the battery containing EX2.2 is 185.3 mAh / g, and the efficiency is 90.8%, both of which are improved compared to the battery containing CEX1.

[0334] As analyzed by ICP-OES, the positive electrode active material CEX2 contains 0.28 mol% of Si relative to the total molar content of Ni, Mn, Co, Si, and Zr, similar to the Si content of EX2.2. The Si B / Si A value of CEX2 is 272.8, and the Si B / Si A value of EX2.2 is 253.3, where CEX2 is prepared by dry mixing with SiO2, and EX2.2 is prepared by mixing with a slurry containing a Si-containing solution.

[0335] It can be clearly observed that Si exists on the surface of the particles, and optionally Zr exists, where the Si B / Si A is greater than 50.0. In particular, the object of the present invention, which is to provide a positive electrode active material having improved initial discharge capacity and improved efficiency, can be achieved by particles prepared by mixing a slurry containing a lithium transition metal-based oxide, Li, and an alcohol with a Si-containing solution.

Claims

1. A positive electrode active material for a solid-state battery, the positive electrode active material comprising Li, M', and oxygen, wherein M' includes: - Ni with a content of x, where 50.0 mol% ≤ x ≤ 95.0 mol% relative to M', - Mn with a content of y, where 0.0 mol% ≤ y ≤ 30.0 mol% relative to M', - Co with a content of z, where 0.0 mol% ≤ z ≤ 30.0 mol% relative to M', - Si with a content of a, where 0.01 mol% ≤ a ≤ 1.5 mol% relative to M', - Zr with a content of b, where 0.0 mol% ≤ b ≤ 1.5 mol% relative to M', - D with a content of d, where D is an element other than Li, Ni, Mn, Co, Si, Zr, and oxygen; where 0.0 mol% ≤ d ≤ 2.0 mol% relative to M', and, - where x, y, z, a, b, and d are measured by ICP-OES, - where x + y + z + a + b + d is 100.0 mol%, wherein the positive electrode active material has an Si content Si A , said Si A is defined as a / (x + y + z + a + b), wherein the positive electrode active material has an Si content of Si B , where Si B is expressed as the ratio of the molar fraction of Si to the sum of the molar fractions of Ni, Mn, Co, Si, and Zr, which is measured by XPS analysis, where the ratio Si B / Si A > 50.

0.

2. The positive electrode active material according to claim 1, wherein 0.0 mol% < b ≤ 1.0 mol% relative to M', preferably 0.05 mol% ≤ b ≤ 0.5 mol%, more preferably 0.1 mol% ≤ b ≤ 0.25 mol%.

3. The positive electrode active material according to claim 1 or 2, wherein the positive electrode active material has a Zr content Zr A , the Zr A is defined as b / (x + y + z + a + b), wherein the positive electrode active material has a Zr content of Zr B , where Zr B , expressed as the ratio of the molar fraction of Zr to the sum of the molar fractions of Ni, Mn, Co, Si, and Zr, which is measured by XPS analysis, wherein the ratio Zr B / Zr A > 50.

0.

4. The positive electrode active material according to any one of the foregoing claims, wherein Si B / Si A > 100.0 and Zr B / Zr A > 100.

0.

5. The positive electrode active material according to any one of the preceding claims, wherein 55.0 mol% ≤ x ≤ 90.0 mol% relative to M', preferably 58.0 mol% ≤ x ≤ 88.0 mol%, more preferably 60.0 mol% ≤ x ≤ 85.0 mol%.

6. The positive electrode active material according to any one of the preceding claims, wherein 0.03 mol% < a ≤ 1.0 mol% relative to M', preferably 0.05 mol% ≤ a ≤ 0.75 mol%, more preferably 0.07 mol% ≤ a ≤ 0.5 mol%.

7. The positive electrode active material according to any one of the preceding claims, wherein D is at least one element selected from the following: Al, B, Ba, Ca, Ce, Cr, Fe, La, Mg, Mo, Nb, S, Sr, Ti, V, W, Y, and Zn; preferably Al, B, Ti, Cr, Nb, S, Y, and W; more preferably Al, B, Ti, Nb, and W.

8. The positive electrode active material according to any one of the preceding claims, the positive electrode active material comprising polycrystalline particles.

9. The positive electrode active material according to claim 8, wherein the median particle size D50 of the secondary particles is between 1 μm and 20 μm, as determined by laser diffraction particle size analysis.

10. A method for manufacturing a positive electrode active material, preferably the positive electrode active material according to any one of claims 1 to 9, wherein the method comprises: - preparing a slurry comprising a lithium transition metal-based oxide compound, a Li source, and an alcohol, - mixing the slurry with a Si source and optionally a Zr source, and - Heat the mixture at a temperature between 250 °C and below 500 °C for a time between 1 hour and 20 hours to obtain the positive electrode active material.

11. The method according to claim 10, wherein the slurry is mixed with an Si source and a Zr source, and the Zr source is a zirconium alkoxide.

12. The method according to claim 10 or 11, wherein the Si source is a silicon alkoxide, an alkylalkoxysilane or a polysiloxane, preferably a silicon alkoxide.

13. A solid-state storage battery comprising the positive electrode active material according to claims 1 to 9.

14. The solid-state storage battery according to claim 13, wherein the solid-state storage battery comprises a sulfide-based solid electrolyte, and the sulfide-based solid electrolyte comprises Li, P and S.

15. Use of the solid-state storage battery according to claim 13 or 14 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.

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