Lithium nickel-based composite oxides as positive electrode active materials for sulfide solid-state rechargeable batteries

Abstract

The present invention relates to a cathode active material for a solid-state battery comprising Li, M', and O, where M' comprises Si and / or Zr. The inventors have surprisingly discovered that the cathode active material of the present invention enhances the cycling efficiency of batteries, particularly sulfide solid-state batteries. Furthermore, these coated cathode active materials exhibit high first-discharge capacity.

Description

[Technical Field]

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

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

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

[0004] Commonly used negative electrode active materials are lithium transition metal oxides. During charging and / or discharging of a lithium battery, the delithiated negative electrode active material can slowly react with the non-aqueous or solid electrolyte, resulting in a gradual deterioration of the electrochemical performance of lithium batteries using such negative electrode active materials.

[0005] It has been demonstrated that coating anode active materials with a metal such as B or Zr (i.e., applying a thin surface layer of a metal onto the cathode active material, resulting in an increased amount of said metal in the surface layer) results in cathode active materials that exhibit higher stability compared to their counterparts lacking the coating layer.

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

[0007] U.S. Pat. No. 10,164,249 discloses a Zr- and F-doped positive electrode active material mixed with an orthosilicate ester solution 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. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] U.S. Patent No. 10,164,249 [Non-patent literature]

[0009] [Non-Patent Document 1] Strauss et al., ACS Appl. Mater. Interfaces 2020, 12, 51, 57146-57154 Summary of the Invention [Problem to be solved by the invention]

[0010] However, there remains a need to provide a positive electrode active material that includes Si and / or Zr to improve the first discharge capacity and / or cycling efficiency of the resulting battery.

[0011] An 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 cycling efficiency of the resulting battery.

[0012] Another object of the present invention is to provide a method for producing the positive electrode active material.

[0013] Another object of the present invention is to provide a battery containing the positive electrode active material.

[0014] Another object of the present invention is to provide a use of said battery. [Means for solving the problem]

[0015] In a first aspect, the object of the present invention is achieved by providing a cathode active material for a solid-state battery comprising Li, M′, and oxygen, wherein M′ is Ni with a content x, with 50.0≦x≦95.0 mol % relative to M′, - Mn with a content y, where 0.0≦y≦30.0 mol % relative to M'; - Co with a content z, with 0.0≦z≦30.0 mol % relative to M′, - Si with a content a, with 0.01≦a≦1.5 mol % relative to M', - Zr with a content b, with 0.0≦b≦1.5 mol % relative to M′, - D with a content d, D being an element other than Li, Ni, Mn, Co, Si, Zr and oxygen, with 0.0≦d≦2.0 mol % relative to M′, - where x, y, z, a, b, and d are measured by ICP-OES, x+y+z+a+b+d is 100.0 mol %, The positive electrode active material has an enriched amount of Si and / or Zr in the surface layer.

[0016] In other words, the positive electrode active material of the present invention has a surface layer containing Si and / or Zr.

[0017] The present inventors have surprisingly discovered that the cathode active materials of the present invention enhance the cycling efficiency of batteries, particularly sulfide solid state batteries, as demonstrated in the accompanying examples. Furthermore, these coated cathode active materials exhibit high first discharge capacities.

[0018] Preferably, the coated active cathode material containing Si and Zr is superior to the corresponding coated active cathode material containing Zr but not Si in terms of first charge discharge capacity and cycling efficiency.

[0019] 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 initial charge / discharge capacity and cycling efficiency. Furthermore, 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 initial charge / discharge capacity and cycling efficiency.

[0020] The positive electrode active material of the present invention containing specific amounts of Si and Zr in the surface layer has the advantage that the resulting battery has a higher discharge capacity and / or a higher cycle efficiency than a positive electrode active material containing the same specific amount of Zr. This has the advantage that a portion of the Zr in the surface layer can be replaced with Si, a metal that is more abundant and cheaper than Zr, to obtain a battery with the same or even higher discharge capacity and / or the same or higher cycle efficiency.

[0021] Preferably, the coated positive electrode active material containing Si rather than Zr is superior to the corresponding coated positive electrode material containing Zr rather than Si in terms of first charge / discharge capacity and cycling efficiency.

[0022] The positive electrode active material of the present invention, which contains a specific amount of Si in the surface layer (but not Zr), has the advantage that the resulting battery has a higher discharge capacity and / or a higher cycling efficiency compared to a positive electrode active material containing the same specific amount of Zr. This has the advantage that the entire Zr in the surface layer can be replaced with Si, a metal that is more abundant and cheaper than Zr, to obtain a battery with the same or even higher discharge capacity and / or the same or higher cycling efficiency.

[0023] Furthermore, the inventors have discovered that the positive electrode active material of the present invention, which contains Si or Si and Zr, improves storage stability. In particular, by applying a surface layer of Si to the positive electrode active material, a reduction in water and carbon (or carbon dioxide) uptake is observed. While not wishing to be bound by any theory, the inventors believe that the Si surface layer acts as a hydrophobic surface layer, suppressing the formation of residual lithium compounds such as Li2CO3. Li2CO3 is formed by a reaction between lithium present in the positive electrode active material and water and carbon in the surrounding air, as the hydrophobic surface inhibits contact between water and the positive electrode active material.

[0024] In a further aspect, the present invention provides a method for producing the cathode active material.

[0025] In a further aspect, the present invention provides a battery comprising the above-described active cathode material.

[0026] In a further aspect, the present invention provides the use of the battery. [Brief explanation of the drawings]

[0027] [Figure 1] FIG. 1 shows the XPS peaks of Si and Zr in EX1.1 (Example 1.1). DETAILED DESCRIPTION OF THE INVENTION

[0028] In the following detailed description, preferred embodiments are described in detail to enable the practice of the invention. Although the invention is described with reference to these specific preferred embodiments, it will be understood that the invention is not limited to these preferred embodiments. On the contrary, the invention includes numerous alternatives, modifications, and equivalents which will become apparent in view of the following detailed description and the accompanying drawings.

[0029] When used in the present specification and claims, the term "comprising" should not be interpreted as being limited to the means described below, nor does it exclude other elements or steps. It should be interpreted as specifying the presence of the mentioned or stated features, integers, steps, or components, but does not preclude the presence or addition of one or more other features, integers, steps, or components, or groups thereof. Thus, the scope of the expression "a composition comprising components A and B" should not be limited to a composition consisting only of components A and B. This means that, in the context of the present invention, the only relevant components of the composition are A and B. Thus, the terms "comprising" and "including" encompass the more restrictive terms "consisting essentially of" and "consisting only of."

[0030] As used herein and in the claims, the term "solid-state battery" refers to a cell or battery that contains only solid or substantially solid components, such as solid electrodes (e.g., anode and cathode) and a solid electrolyte.

[0031] As used herein and in the claims, the term "cathode active material" (also known as cathode active material) is defined as a material that is electrochemically active within a cathode or cathode. By active material, it should be understood that the material is capable of capturing and releasing Li-ions when subjected to a voltage change over a period of time.

[0032] As used herein, the term "cathode" is defined as a material that includes a cathode active material, particularly a conductive agent, such as a binder, such as carbon black or PVDF, in addition to other components that are not electrochemically active.

[0033] As used herein and in the claims, the term "slurry" refers to a mixture, premix, and / or admixture of solid particles suspended in a liquid, such as water, alcohol, or a combination thereof. When using the term "slurry," the solid particles are not dissolved or not completely dissolved in the liquid. For example, a slurry of a lithium transition metal-based oxide compound is a suspension of 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 not completely dissolved in the liquid.

[0034] In the context of the present invention, the terms "solid" and "liquid" should be considered as those which are considered to be solids and liquids under standard conditions of temperature and pressure as defined by IUPAC, unless otherwise defined. Hereby, boiling points and melting points should be considered as boiling points and melting points at standard atmospheric pressure, i.e., 101,325 Pa.

[0035] <Cathode active material> In a first aspect, the present invention relates to a cathode active material for a solid-state battery comprising Li, M′, and oxygen, where M′ is: Ni with a content x, with 50.0≦x≦95.0 mol % relative to M′, - Mn with a content y, where 0.0≦y≦30.0 mol % relative to M'; - Co with a content z, with 0.0≦z≦30.0 mol % relative to M′, - Si with a content a, with 0.01≦a≦1.5 mol % relative to M', - Zr with a content b, where 0.0≦b≦1.5 mol % relative to M', and - D with a content d, D being an element other than Li, Ni, Mn, Co, Si, Zr and oxygen, with 0.0≦d≦2.0 mol % relative to M′, - where x, y, z, a, b, and d are measured by ICP-OES, x+y+z+a+b+d is 100.0 mol %, The positive electrode active material has a Si content defined as a / (x+y+z+a+b) A and The positive electrode active material has a Si content of Si B and Si B is expressed as the mole fraction Si compared to the sum of the mole fractions of Ni, Mn, Co, Si, and Zr, as measured by XPS analysis, and the ratio Si B / Si A is greater than 50.0 (>50.0).

[0036] A preferred embodiment is a positive electrode active material of the present invention, in which the Ni content x, relative to M', satisfies x≧55.0 mol%, preferably x≧58.0 mol%, and more preferably x≧60.0 mol%. In a preferred embodiment, the Ni content x, relative to M', satisfies x≦90.0 mol%, preferably x≦88 mol%, and more preferably x≦85.0 mol%. A more preferred embodiment is a positive electrode active material of the present invention, in which the Ni content x, relative to M', satisfies 55.0 mol%≦x≦90.0 mol%, preferably 58.0 mol%≦x≦88.0 mol%, and more preferably 60.0 mol%≦x≦85.0 mol%.

[0037] A particularly preferred embodiment is a positive electrode active material of the present invention, in which the Ni content x, relative to M', satisfies x≧55.0 mol%, preferably x≧58.0 mol%, and more preferably x≧60.0 mol%. In a particularly preferred embodiment, the Ni content x, relative to M', satisfies x≦75.0 mol%, preferably x≦72 mol%, and more preferably x≦70.0 mol%. A more particularly preferred embodiment is a positive electrode active material of the present invention, in which the Ni content x, relative to M', satisfies 55.0 mol%≦x≦75.0 mol%, preferably 58.0 mol%≦x≦72.0 mol%, and more preferably 60.0 mol%≦x≦70.0 mol%.

[0038] A particularly preferred embodiment is a positive electrode active material of the present invention, in which the Ni content x, relative to M', satisfies x≧75.0 mol%, preferably x≧78.0 mol%, and more preferably x≧80.0 mol%. In a particularly preferred embodiment, the Ni content x, relative to M', satisfies x≦92.0 mol%, preferably x≦90 mol%, and more preferably x≦88.0 mol%. A more particularly preferred embodiment is a positive electrode active material of the present invention, in which the Ni content x, relative to M', satisfies 75.0 mol%≦x≦92.0 mol%, preferably 78.0 mol%≦x≦90.0 mol%, and more preferably 80.0 mol%≦x≦88.0 mol%.

[0039] As will be 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 spectroscopy (ICP-OES). For example, but not limited to, an Agilent ICP 720-ES is used for ICP-OES analysis.

[0040] A preferred embodiment is a positive electrode active material of the present invention, wherein the content y of Mn is y > 0.0 mol% with respect to M', preferably y ≥ 5.0 mol%, more preferably y ≥ 10.0 mol%. In a preferred embodiment, the content is y ≤ 30.0 mol% with respect to M', preferably y ≤ 25.0 mol%, more preferably y ≤ 20.0 mol%. In a preferred embodiment, for Mn, the content y is 0.0 mol% < y ≤ 30.0 mol% with respect to M', preferably 5.0 mol% ≤ y ≤ 25.0 mol%, more preferably 10.0 mol% ≤ y ≤ 20.0 mol%.

[0041] A specific preferred embodiment is a positive electrode active material of the present invention, wherein the content y of Mn is y > 0.0 mol% with respect to M', preferably y ≥ 1.0 mol%, more preferably y ≥ 2.0 mol%. In a preferred embodiment, the content is y ≤ 20.0 mol% with respect to M', preferably y ≤ 15.0 mol%, more preferably y ≤ 10.0 mol%. In a preferred embodiment, for Mn, the content y is 0.0 mol% < y ≤ 20.0 mol% with respect to M', preferably 1.0 mol% ≤ y ≤ 15.0 mol%, more preferably 2.0 mol% ≤ y ≤ 10.0 mol%.

[0042] A preferred embodiment is a positive electrode active material of the present invention, wherein the content z of Co is z > 0.0 mol% with respect to M', preferably z ≥ 5.0 mol%, more preferably z ≥ 10.0 mol%. In a preferred embodiment, the content is z ≤ 30.0 mol% with respect to M', preferably z ≤ 25.0 mol%, more preferably z ≤ 20.0 mol%. In a preferred embodiment, for Co, the content z is 0.0 mol% < z ≤ 30.0 mol% with respect to M', preferably 5.0 mol% ≤ z ≤ 25.0 mol%, more preferably 10.0 mol% ≤ z ≤ 20.0 mol%.

[0043] A specific preferred embodiment is a positive electrode active material of the present invention, wherein Co has a content z of z > 0.0 mol%, preferably z ≥ 1.0 mol%, more preferably z ≥ 2.0 mol% with respect to M'. In a preferred embodiment, its content is z ≤ 20.0 mol%, preferably z ≤ 15.0 mol%, more preferably z ≤ 10.0 mol% with respect to M'. In a preferred embodiment, Co has a content z of 0.0 mol% < z ≤ 20.0 mol%, preferably 1.0 mol% ≤ z ≤ 15.0 mol%, more preferably 2.0 mol% ≤ z ≤ 10.0 mol% with respect to M'.

[0044] 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 to obtain a whole positive electrode active material containing one or more elements other than Li, Ni, Mn, Co, Zr, Si, and O, and these are reflected in the parameter "D" used herein. A preferred embodiment is a positive electrode active material according to 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.

[0045] A preferred embodiment is a positive electrode active material according to the present invention, wherein D has a content d of d > 0.0 mol%, preferably d ≥ 0.25 mol%, more preferably d ≥ 0.5 mol% with respect to M'. In a preferred embodiment, its content d is d ≤ 1.75 mol%, preferably d ≤ 1.5 mol%, more preferably d ≤ 1.25 mol% with respect to M'. In a preferred embodiment, its 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% with respect to M'.

[0046] In a specific preferred embodiment, the positive electrode active material has d = 0.0 mol% with respect to M' according to the present invention.

[0047] A preferred embodiment is a positive electrode active material according to the present invention, wherein the content a of Si is a > 0.03 mol% with respect to M', preferably a ≧ 0.05 mol%, more preferably a ≧ 0.07 mol%. A more specific preferred embodiment is a positive electrode active material according to the present invention, wherein the content a of Ni is a ≦ 1.0 mol% with respect to M', preferably a ≦ 0.75 mol%, more preferably a ≦ 0.5 mol%. In a preferred embodiment, the content a is 0.03 mol% < a ≦ 1.0 mol% with respect to M', preferably 0.05 mol% ≦ a ≦ 0.75 mol%, more preferably 0.07 mol% ≦ a ≦ 0.5 mol%.

[0048] In a specific preferred embodiment, the positive electrode active material is b > 0.0 mol% with respect to M' according to the present invention.

[0049] A specific very preferred embodiment is a positive electrode active material according to the present invention, wherein the content b of Zr is b > 0.0 mol% with respect to M', preferably b ≧ 0.05 mol%, more preferably b ≧ 0.1 mol%. In a preferred embodiment, the content b is b ≦ 1.0 mol% with respect to M', preferably b ≦ 0.5 mol%, more preferably b ≦ 0.25 mol%. In a preferred embodiment, the content b is 0.0 mol% < b ≦ 1.0 mol% with respect to M', preferably 0.05 mol% ≦ b ≦ 0.5 mol%, more preferably 0.1 mol% ≦ b ≦ 0.25 mol%.

[0050] In a specific preferred embodiment, the positive electrode active material is b = 0.0 mol% with respect to M' according to the present invention.

[0051] In a preferred embodiment, the positive electrode active material consists of only Li, M' and O.

[0052] In a specific preferred embodiment, the positive electrode active material is according to the present invention, Si has a content a of 0.03 mol% < a ≤ 1.0 mol% with respect to M', preferably 0.05 mol% ≤ a ≤ 0.75 mol%, more preferably 0.07 mol% ≤ a ≤ 0.5 mol%, and b = 0.0 mol% with respect to M'.

[0053] Preferred embodiments are the positive electrode active materials of the present invention having a carbon content of more than 0.020% by weight, more than 0.022% by weight of the total weight of the positive electrode active material, more preferably a carbon content of more than 0.025% by weight of the total weight of the positive electrode active material. Preferred embodiments are the positive electrode active materials of the present invention having a carbon content of less than 0.070% by weight of the total weight of the positive electrode active material, preferably less than 0.060% by weight, more preferably a carbon content of less than 0.050% by weight of the total weight of the positive electrode active material. Preferred embodiments are the positive electrode active materials of the present invention having a carbon content in the range of 0.020% to 0.070% by weight of the total weight of the positive electrode active material, preferably in the range of 0.022% to 0.060% by weight, more preferably a carbon content in the range of 0.025% to 0.050% by weight of the total weight of the positive electrode active material. As will be understood by those skilled in the art, the carbon content of the positive electrode active material of the present invention is measured by a carbon analyzer. For example, without being limited to the present invention, a Horiba Emia-Expert carbon / sulfur analyzer can be used to measure the carbon content.

[0054] A preferred embodiment is the positive electrode active material of the present invention having a Li / M' ratio, preferably a Li / (Ni + Mn + Co) ratio, greater than 0.90, preferably greater than 0.92, more preferably greater than 0.95. A preferred embodiment is the positive electrode active material of the present invention having a Li / M' ratio, preferably a Li / (Ni + Mn + Co) ratio, less than 1.10, preferably less than 1.08, more preferably less than 1.05. A preferred embodiment is the positive electrode active material of the present invention having a Li / M' ratio, preferably a Li / (Ni + Mn + Co) ratio, in the range of 0.90 to 1.10, preferably in the range of 0.92 to 1.08, more preferably in the range of 0.95 to 1.05. As understood by those skilled in the art, the Li / M' ratio, preferably the Li / (Ni + Mn + Co) ratio, is a molar ratio (mol / mol).

[0055] A highly preferred embodiment is the positive electrode active material according to the present invention, having the formula (I): Li w2 Ni x2 Mn y2 Co z2 Si a2 Zr b2 D2 d2 O2(I) wherein 0.90 ≤ w2 ≤ 1.10, preferably 0.92 ≤ w2 ≤ 1.08, more preferably 0.95 ≤ w2 ≤ 1.05, 0.55 ≤ x2 ≤ 0.90, preferably 0.58 ≤ x2 ≤ 0.88, more preferably 0.60 ≤ x2 ≤ 0.85, 0.0 < y2 ≤ 0.30, preferably 0.05 ≤ y2 ≤ 0.25, more preferably 0.10 ≤ y2 ≤ 0.20, 0.0 < z2 ≤ 0.30, preferably 0.05 ≤ z2 ≤ 0., more preferably 0.10 ≤ z2 ≤ 0.20, 0.0003 ≤ a2 ≤ 0.01, preferably 0.0005 ≤ a2 ≤ 0.0075, more preferably 0.0007 ≤ a2 ≤ 0.005, 0.0 < b2 ≤ 0.01, preferably 0.0005 ≤ b2 ≤ 0.005, more preferably 0.0001 ≤ b2 ≤ 0.0025, 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; x²+y²+z²+a²+b²+d²=1.00, and D2 is a positive electrode active material that is an element other than Li, O, Ni, Co, Mn, Z, and Si.

[0056] In certain preferred embodiments, 0.55≦x2≦0.75, preferably 0.58≦x2≦0.72, and more preferably 0.60≦x2≦0.70.

[0057] As known to those skilled in the art, the active cathode materials of the present invention can contain impurities or be doped or coated to provide an overall active cathode material that includes one or more elements other than Li, Ni, Mn, Co, Zr, Si, and O, which are reflected in the parameter "D2" used herein. A preferred embodiment is an active cathode material of the present invention that includes 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.

[0058] <Surface layer> 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 defined as a / (x+y+z+a+b). A The positive electrode active material has a Si content of Si B and Si B is expressed as mole fraction Si relative to the sum of the mole fractions of Ni, Mn, Co, Si, and Zr, as measured by XPS analysis, and is the ratio Si B / Si A is greater than 50.0 (>50.0).

[0059] A more preferred embodiment is a positive electrode active material according to the present invention, wherein the ratio SiB / Si A is greater than 100.0, preferably the ratio Si B / Si A is more than 200.0, more preferably, the ratio Si B / Si A A more preferred embodiment of the present invention relates to a positive electrode active material in which the ratio Si B / Si A is less than 1000.0, preferably the ratio Si B / Si A is less than 600.0, more preferably, the ratio Si B / Si A A more preferred embodiment of the present invention relates to a positive electrode active material in which the ratio Si B / Si A is in the range of 100.0 to 1000.0, preferably, the ratio Si B / Si A is in the range of 200.0 to 600.0, more preferably, the ratio Si B / Si A is in the range of 250.0 to 400.0.

[0060] A particularly preferred embodiment is a cathode active material according to the present invention, which has a ratio of Si B / Si A A particularly preferred embodiment relates to a positive electrode active material according to the present invention, wherein the ratio Si B / Si A A particularly preferred embodiment relates to a positive electrode active material according to the present invention, wherein the ratio Si B / Si A is in the range of 300.0 to 400.0.

[0061] In the context of the present invention, Si Bis the mole fraction of Si measured in a region of a particle of the positive electrode active material according to the present invention defined between a first point on the outer edge of the particle and a second point spaced from the first point. The distance separating the first and second points is equal to the XPS penetration depth, D', which is in the range of 1.0 to 10.0 nm. In particular, the penetration depth is the distance along an axis perpendicular to an imaginary line tangent to the outer edge and passing through the first point.

[0062] The outer edge of a particle is, in the context of the present invention, the boundary or outer limit that distinguishes the particle from its external environment. Therefore, XPS analysis indicates the atomic content of elements in the uppermost layer of the particle, with a penetration depth of approximately 10.0 nm from the outer boundary of the particle. The outer boundary of the particle is also referred to as the "surface." For example, and not limiting to the present invention, XPS analysis is performed using a Thermo K-α+ spectrometer (Thermo Scientific).

[0063] In the framework of the present invention, at% means atomic percentage. The at% or "atomic percentage" of the concentration expression of a given element means what percentage of all atoms in the compound are atoms of said element. Furthermore, in the framework of the present invention, the designation at% is equivalent to mole% or "mole percent".

[0064] As will be appreciated by those skilled in the art, this defined ratio Si B / Si A " refers to a cathode active material of the present invention having an enriched amount of Si in the surface layer of the cathode active material. The surface layer of the cathode active material is the topmost 1 to 10 nm of the cathode active material. In other words, the cathode active material of the present invention includes a surface layer of Si. For example, although not limited to the present invention, the Si compound present in the surface layer of the cathode active material is Li2SiO3.

[0065] 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, and is preferably Al, B, Ti, Cr, Nb, S, Y, and W, and more preferably Al, B, Ti, Nb, and W; a surface layer of Si may be disposed on the first surface layer; and / or the first surface layer may be disposed 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.

[0066] A preferred embodiment is a positive electrode active material according to the present invention, wherein the positive electrode active material has a Zr content Zr defined as b / (x+y+z+a+b). A The positive electrode active material has a Zr content of Zr B and Zr B is expressed as mole fraction Zr relative to the sum of mole fractions of Ni, Mn, Co, Si, and Zr when measured by XPS analysis, and the ratio Zr B / Zr A relates to a positive electrode active material having a % saturation of more than 50.0.

[0067] A more preferred embodiment is a positive electrode active material according to the present invention, wherein the ratio of Zr B / Zr A is more than 75.0, preferably the ratio Zr B / Zr A is more than 100.0, more preferably, the ratio Zr B / Zr A A more preferred embodiment of the present invention relates to a positive electrode active material having a ratio Zr B / Zr A is less than 1000.0, preferably the ratio Zr B / Zr A is less than 600.0, more preferably, the ratio Zr B / Zr A A more preferred embodiment of the present invention relates to a positive electrode active material having a ratio of Zr B / ZrA is in the range of 75.0 to 1000.0, preferably the ratio Zr B / Zr A is in the range of 100.0 to 600.0, more preferably, the ratio Zr B / Zr A is in the range of 150.0 to 400.0.

[0068] A particularly preferred embodiment is a cathode active material according to the present invention, which has a ratio of Zr B / Zr A A particularly preferred embodiment relates to a cathode active material according to the present invention, wherein the ratio Zr B / Zr A A particularly preferred embodiment relates to a cathode active material according to the present invention, wherein the ratio Zr B / Zr A is in the range of 275.0 to 350.0.

[0069] In the context of the present invention, Zr B is the mole fraction of Zr measured in a region of a particle of the positive electrode active material according to the present invention, defined between a first point on the outer edge of the particle and a second point spaced from the first point. The distance separating the first point from the second point is equal to the XPS penetration depth, D', which is in the range of 1.0 to 10.0 nm. In particular, the penetration depth is the distance along an axis perpendicular to an imaginary line tangent to the outer edge and passing through the first point.

[0070] As will be understood by those skilled in the art, the defined ratio Zr B / Zr A "Zr" refers to a cathode active material of the present invention having an enriched amount of Zr in the surface layer of the cathode active material. The surface layer of the cathode active material is the topmost 1 to 10 nm of the cathode active material. In other words, the cathode active material of the present invention includes a Zr surface layer. For example, but not limited to, the Zr compound present in the surface layer of the cathode active material is Li2ZrO3.

[0071] 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, and is preferably Al, B, Ti, Cr, Nb, S, Y, and W, and more preferably Al, B, Ti, Nb, and W; a surface layer of Zr may be disposed on the second surface layer, and / or the second surface layer may be disposed on the surface layer of Zr; and / or the positive electrode active layer may include a mixed surface layer including a surface layer of Zr and the second surface layer.

[0072] Certain preferred embodiments relate to a cathode active material according to the present invention, the cathode active material comprising: Si content defined as a / (x+y+z+a+b) A The positive electrode active material has a Si content of Si B and Si B is expressed as the mole fraction Si relative to the sum of the mole fractions of Ni, Mn, Co, Si, and Zr, as measured by XPS analysis, and the ratio Si B / Si A is greater than 50.0, preferably the ratio Si B / Si A is a Si content of more than 100 A and, Zr content defined as b / (x+y+z+a+b) A The positive electrode active material has a Zr content of Zr B and Zr B is expressed as the mole fraction Zr relative to the sum of the mole fractions of Ni, Mn, Co, Si, and Zr, as measured by XPS analysis, and the ratio Zr B / Zr A is greater than 50.0, preferably Zr B / ZrA is a Zr content greater than 100. A and It has.

[0073] A more particular preferred embodiment relates to a cathode active material according to the present invention, wherein: · Specific SiB / Si A is in the range of 100.0 to 1000.0, and preferably, the ratio Si B / Si A is in the range of 200.0 to 600.0, and more preferably, the ratio Si B / Si A is in the range of 250.0 to 400.0, Zr ratio B / Zr A is in the range of 75.0 to 1000.0, and preferably, the ratio Zr B / Zr A is in the range of 100.0 to 600.0, and more preferably, the ratio Zr B / Zr A is in the range of 150.0 to 400.0.

[0074] Certain preferred embodiments relate to cathode active materials according to the invention, wherein: · Specific Si B / Si A is in the range of 300.0 to 400.0, Zr ratio B / Zr A is in the range of 275.0 to 350.0.

[0075] As will be understood by those skilled in the art, the defined ratio Zr B / Zr A and Si B / Si A " refers to a cathode active material of the present invention having enriched amounts of Zr and Si in the surface layer of the cathode active material. The surface layer of the cathode active material is the topmost 1 to 10 nm of the cathode active material. In other words, the cathode active material of the present invention includes a surface layer of Zr and Si. For example, but not limited to, the compound of Si and Zr present in the surface layer of the cathode active material is Li2Si 0.5 Zr 0.5 It is O3.

[0076] In the context of the present invention, the positive electrode active material may include a third surface layer containing D, where D is at least one element selected from the group consisting of Al, B, Ba, Ca, Ce, Cr, Fe, La, Mg, Mo, Nb, S, Sr, Ti, V, W, Y, and Zn, and is preferably Al, B, Ti, Cr, Nb, S, Y, and W, and more preferably Al, B, Ti, Nb, and W; a surface layer of Zr and Si may be disposed on the third surface layer, and / or the third surface layer may be disposed on the surface layer of Zr and Si; and / or the positive electrode active layer may include a mixed surface layer including the surface layer of Zr and Si and the second surface layer.

[0077] Certain preferred embodiments relate to cathode active materials according to the present invention, wherein · Specific Si B / Si A is in the range of 100.0 to 1000.0, and preferably, the ratio Si B / Si A is in the range of 200.0 to 600.0, and more preferably, the ratio Si B / Si A is in the range of 250.0 to 400.0, The carbon content is in the range of 0.020 wt % to 0.070 wt % of the total weight of the positive electrode active material, preferably in the range of 0.022 wt % to 0.060 wt %, and more preferably in the range of 0.025 wt % to 0.050 wt % of the total weight of the positive electrode active material.

[0078] Certain preferred embodiments relate to cathode active materials according to the present invention, wherein Zr ratio B / Zr A is in the range of 75.0 to 1000.0, and preferably, the ratio Zr B / Zr A is in the range of 100.0 to 600.0, and more preferably, the ratio Zr B / Zr A is in the range of 150.0 to 400.0, The carbon content is in the range of 0.020 wt % to 0.070 wt % of the total weight of the positive electrode active material, preferably in the range of 0.022 wt % to 0.060 wt %, and more preferably in the range of 0.025 wt % to 0.050 wt % of the total weight of the positive electrode active material.

[0079] A more particular preferred embodiment relates to a positive electrode active material according to the present invention, · Specific Si B / Si A is in the range of 100.0 to 1000.0, and preferably, the ratio Si B / Si A is in the range of 200.0 to 600.0, and more preferably, the ratio Si B / Si A is in the range of 250.0 to 400.0, Zr ratio B / Zr A is in the range of 75.0 to 1000.0, and preferably, the ratio Zr B / Zr A is in the range of 100.0 to 600.0, and more preferably, the ratio Zr B / Zr A is in the range of 150.0 to 400.0, The carbon content is in the range of 0.020 wt % to 0.070 wt % of the total weight of the positive electrode active material, preferably in the range of 0.022 wt % to 0.060 wt %, and more preferably in the range of 0.025 wt % to 0.050 wt % of the total weight of the positive electrode active material.

[0080] A preferred embodiment of the present invention relates to a positive electrode active material according to the present invention, wherein the positive electrode active material has a Si content of Si B and Si B is expressed as mole fraction Si relative to the sum of the mole fractions of Ni, Mn, Co, Si, and Zr, as measured by XPS analysis, and Si B is greater than 0.25, preferably Si B is more than 0.5, more preferably Si B A preferred embodiment of the present invention relates to a positive electrode active material according to the present invention, wherein SiB is less than 5.0, preferably Si B is less than 2.0, more preferably Si B is less than 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 to 5.0, preferably Si B is in the range of 0.5 to 2.0, more preferably Si B is in the range of 0.75 to 1.0.

[0081] 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 of Zr B and Zr B is expressed as mole fraction Zr relative to the sum of mole fractions of Ni, Mn, Co, Si, and Zr, as determined by XPS analysis, and Zr B is greater than 0.25, preferably Zr B is more than 0.4, more preferably Zr B is greater than 0.5. A preferred embodiment relates to a positive electrode active material according to the present invention, wherein Zr B is less than 2.0, preferably Zr B is less than 0.9, more preferably Zr B A preferred embodiment relates to a positive electrode active material according to the present invention, comprising Zr B is in the range of 0.25 to 2.0, and preferably Zr B is in the range of 0.4 to 0.9, and more preferably Zr B is in the range of 0.5 to 0.8.

[0082] Certain preferred embodiments relate to cathode active materials according to the present invention, wherein Si B is in the range of 0.25 to 5.0, and preferably Si B is in the range of 0.5 to 2.0, and more preferably, Si B is in the range of 0.75 to 1.0, The content b of Zr relative to M' is b=0.0 mol%.

[0083] <Morphology> In certain preferred embodiments, the cathode active material of the present invention comprises single-crystal particles. In the context of the present invention, a particle is considered to be single-crystal if it consists of only one particle or at most five particles, preferably at most three particles, as determined by scanning electron microscopy (SEM) or transmission electron microscopy (TEM), preferably by observing the grain boundaries of the particles. A grain boundary is defined as the interface between two particles within a particle, and preferably, the atomic planes of the two particles are aligned in different orientations and intersect as a crystalline discontinuity.

[0084] A more particular preferred embodiment relates to a positive electrode active material according to the present invention, the positive electrode active material comprising: Contains single crystal particles, ratio Si B / Si A is in the range of 100.0 to 1000.0, and preferably, the ratio Si B / Si A is in the range of 200.0 to 600.0, and more preferably, the ratio Si B / Si A is in the range of 250.0 to 400.0.

[0085] A more particular preferred embodiment relates to a positive electrode active material according to the present invention, the positive electrode active material comprising: Contains single crystal particles, Zr ratio B / Zr A is in the range of 75.0 to 1000.0, and preferably, the ratio Zr B / Zr A is in the range of 100.0 to 600.0, and more preferably, the ratio Zr B / Zr A is in the range of 150.0 to 400.0.

[0086] A more particular preferred embodiment relates to a positive electrode active material according to the present invention, the positive electrode active material comprising: Contains single crystal particles, The carbon content is in the range of 0.020% by weight to 0.070% by weight, preferably 0.022% by weight to 0.060% by weight, and more preferably 0.025% by weight to 0.050% by weight, of the total weight of the positive electrode active material.

[0087] A more particular preferred embodiment relates to a positive electrode active material according to the present invention, the positive electrode active material comprising: Contains single crystal particles, ratio Si B / Si A is in the range of 100.0 to 1000.0, and preferably, the ratio Si B / Si A is in the range of 200.0 to 600.0, and more preferably, the ratio Si B / Si A is in the range of 250.0 to 400.0, Zr ratio B / Zr A is in the range of 75.0 to 1000.0, and preferably, the ratio Zr B / Zr A is in the range of 100.0 to 600.0, and more preferably, the ratio Zr B / Zr A is in the range of 150.0 to 400.0.

[0088] A more particular preferred embodiment relates to a positive electrode active material according to the present invention, the positive electrode active material comprising: Contains single crystal particles, ratio Si B / Si A is in the range of 100.0 to 1000.0, and preferably, the ratio Si B / Si A is in the range of 200.0 to 600.0, and more preferably, the ratio Si B / Si A is in the range of 250.0 to 400.0, Zr ratio B / Zr A is in the range of 75.0 to 1000.0, and preferably, the ratio Zr B / Zr Ais in the range of 100.0 to 600.0, and more preferably, the ratio Zr B / Zr A is in the range of 150.0 to 400.0, The carbon content is in the range of 0.020% by weight to 0.070% by weight, preferably 0.022% by weight to 0.060% by weight, and more preferably 0.025% by weight to 0.050% by weight, of the total weight of the positive electrode active material.

[0089] As will be understood by those skilled in the art, the single crystal particles have a Si content of A , Si B , Zr A , and / or Zr B , and their corresponding ratios.

[0090] In certain preferred embodiments of the present invention, and in the context of the present invention, the single-crystal particles as defined herein are monolithic particles. In these certain preferred embodiments, as will be understood by those skilled in the art, all embodiments relating to single-crystal particles apply equally to the monolithic particles as defined in the present invention.

[0091] In a particularly preferred embodiment, the present invention provides a cathode active material according to the present invention, wherein the cathode active material is a powder including single particles and / or secondary particles, and when observed in an SEM image, each single particle is composed of only one primary particle, and each secondary particle is composed of at least two primary particles and at most 20 primary particles.

[0092] Preferably, at least 30% of the particles, more preferably at least 50% of the particles, constituting the powder observed in the SEM image are single particles and / or secondary particles. The number of primary particles constituting the single particles and / or secondary particles is at least 45 μm by 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 ) is determined by the field of view.

[0093] The particles in the image should therefore be well distributed to avoid overlap between particles. This can be achieved by pouring a small amount of powder sample onto an adhesive attached to the SEM sample holder and blowing air to remove excess powder.

[0094] In the context of the present invention, primary particles are distinguished from one another in SEM images by observing the grain boundaries between the primary particles, which are defined as the interface between two primary particles, where preferably the atomic planes of the two primary particles are aligned in different orientations and meet as a crystalline discontinuity.

[0095] As will be understood by those skilled in the art, polycrystalline particles are aggregates of more than 20 primary particles, preferably 50 or more primary particles, and more preferably 100 or more primary particles. Thus, in certain preferred embodiments, the positive electrode active material is a powder containing polycrystalline particles, each of which, as observed in an SEM image, consists of more than 20 primary particles, preferably 50 or more primary particles, and more preferably 100 or more primary particles.

[0096] Preferably, at least 30% of the particles constituting the powder observed in the SEM image, more preferably at least 50% of the particles, are polycrystalline particles. The number of primary particles constituting the polycrystalline particles is 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 ) is determined by the field of view. The particles in the image should therefore be well distributed to avoid overlap between particles. This can be achieved by pouring a small amount of powder sample onto an adhesive attached to the SEM sample holder and blowing air to remove excess powder.

[0097] In certain preferred embodiments, the cathode active material of the present invention comprises polycrystalline particles. As will be understood by those skilled in the art, polycrystalline particles are aggregates of 5 or more single-crystal particles, preferably 10 or more single-crystal particles, and more preferably 50 or more single-crystal particles. This can be observed by suitable microscopy techniques, such as scanning electron microscopy (SEM), by observing the grain boundaries. The aggregation of single-crystal particles into polycrystalline particles occurs during post-treatment processes, such as heat treatment processes.

[0098] A more particular preferred embodiment relates to a positive electrode active material according to the present invention, the positive electrode active material comprising: Contains polycrystalline particles, ratio Si B / Si A is in the range of 100.0 to 1000.0, and preferably, the ratio Si B / Si A is in the range of 200.0 to 600.0, and more preferably, the ratio Si B / Si A is in the range of 250.0 to 400.0.

[0099] A more particular preferred embodiment relates to a positive electrode active material according to the present invention, the positive electrode active material comprising: Contains polycrystalline particles, Zr ratio B / Zr A is in the range of 75.0 to 1000.0, and preferably, the ratio Zr B / Zr A is in the range of 100.0 to 600.0, and more preferably, the ratio Zr B / Zr A is in the range of 150.0 to 400.0.

[0100] A more particular preferred embodiment relates to a positive electrode active material according to the present invention, the positive electrode active material comprising: Contains polycrystalline particles, The carbon content is in the range of 0.020% by weight to 0.070% by weight, preferably 0.022% by weight to 0.060% by weight, and more preferably 0.025% by weight to 0.050% by weight, of the total weight of the positive electrode active material.

[0101] A more particular preferred embodiment relates to a positive electrode active material according to the present invention, the positive electrode active material comprising: Contains polycrystalline particles, ratio Si B / Si A is in the range of 100.0 to 1000.0, and preferably, the ratio Si B / Si A is in the range of 200.0 to 600.0, and more preferably, the ratio Si B / Si A is in the range of 250.0 to 400.0, Zr ratio B / Zr A is in the range of 75.0 to 1000.0, and preferably, the ratio Zr B / Zr A is in the range of 100.0 to 600.0, and more preferably, the ratio Zr B / Zr A is in the range of 150.0 to 400.0.

[0102] A more particular preferred embodiment relates to a positive electrode active material according to the present invention, the positive electrode active material comprising: Contains polycrystalline particles, ratio Si B / Si A is in the range of 100.0 to 1000.0, and preferably, the ratio Si B / Si A is in the range of 200.0 to 600.0, and more preferably, the ratio Si B / Si A is in the range of 250.0 to 400.0, Zr ratio B / Zr A is in the range of 75.0 to 1000.0, and preferably, the ratio Zr B / Zr Ais in the range of 100.0 to 600.0, and more preferably, the ratio Zr B / Zr A is in the range of 150.0 to 400.0, The carbon content is in the range of 0.020 wt % to 0.070 wt % of the total weight of the positive electrode active material, preferably in the range of 0.022 wt % to 0.060 wt %, and more preferably in the range of 0.025 wt % to 0.050 wt % of the total weight of the positive electrode active material.

[0103] Certain preferred embodiments relate to a cathode active material according to the present invention, the cathode active material comprising: Contains polycrystalline particles, Si B is in the range of 0.25 to 5.0, and preferably, Si B is in the range of 0.5 to 2.0, and more preferably, Si B is in the range of 0.75 to 1.0, The content b of Zr relative to M' is b=0.0 mol %.

[0104] As will be understood by those skilled in the art, the polycrystalline particles have a Si content of A , Si B , Zr A , and / or Zr B , and their corresponding ratios.

[0105] 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. In these certain preferred embodiments, as will be understood by those skilled in the art, all embodiments relating to polycrystalline particles apply equally to secondary particles as defined in the present invention.

[0106] Certain preferred embodiments relate to cathode active materials of the present invention comprising single-crystal particles having a primary particle median D50 value of less than 10 μm, preferably less than 8 μm, and more preferably less than 5 μm. Certain preferred embodiments relate to cathode active materials of the present invention comprising single-crystal particles having a primary particle median D50 value of greater than 1 μm, preferably greater than 2 μm, and more preferably greater than 3 μm. Certain preferred embodiments relate to cathode active materials of the present invention comprising single-crystal particles having a primary particle median D50 value of 1 to 10 μm, preferably 2 to 8 μm, and more preferably 3 to 5 μm. As will be understood by those skilled in the art, the particle size distribution (PSD) D50 of cathode active material powders is measured by laser diffraction particle size analysis. Preferably, D50 is defined as the volume average particle diameter, and more preferably, the particle size at 50% of the cumulative volume percent distribution is obtained from a Malvern Mastersizer 3000 equipped with Hydro MV measurement. For example, but not limited to, the particle median D50 can be measured using a Malvern Mastersizer 3000. Certain preferred embodiments relate to cathode active materials of the present invention comprising polycrystalline particles having a D50 value of less than 20 μm, preferably less than 15 μm, and more preferably less than 12 μm. Certain preferred embodiments relate to cathode active materials of the present invention comprising polycrystalline particles having a secondary particle median D50 value of greater than 1 μm, preferably greater than 3 μm, and more preferably greater than 5 μm. Certain preferred embodiments relate to cathode active materials of the present invention comprising polycrystalline particles having a secondary particle median D50 value of 1 to 20 μm, preferably 3 to 15 μm, and more preferably 5 to 12 μm. As will be understood by those skilled in the art, the particle size distribution (PSD) D50 of cathode active material powders 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 by a Malvern Mastersizer 3000 equipped with Hydro MV measurement. For example, but not limiting to the present invention, particle median D50 can be measured using a Malvern Mastersizer 3000.

[0107] In a further aspect, the present invention provides a secondary particle-based cathode active material for a solid-state battery, comprising Li, M′, and oxygen; where M' is: Ni with a content x, with 50.0≦x≦95.0 mol % relative to M′, - Mn with a content y, where 0.0≦y≦30.0 mol % relative to M'; - Co with a content z, with 0.0≦z≦30.0 mol % relative to M′, - a content a of Si, which is 0.01≦1.5 mol % relative to M′, and - Zr with a content b, with 0.0≦b≦1.5 mol % relative to M′, - D with a content d, where D is an element other than Li, Ni, Mn, Co, Si, Zr and oxygen, and where 0.0≦d≦2.0 mol % relative to M′; Including, - where x, y, z, a, b, and d are measured by ICP-OES, x+y+z+a+b+d is 100.0 mol %, The positive electrode active material has a Si content defined as a / (x+y+z+a+b) A The positive electrode active material has a Si content of Si B and Si B is expressed as mole fraction Si relative to the sum of the mole fractions of Ni, Mn, Co, Si, and Zr, as measured by XPS analysis, and is the ratio Si B / Si A is greater than 50.0.

[0108] In a highly preferred embodiment of the secondary particle-based positive electrode active material, all embodiments directed to the positive electrode active material according to the first aspect of the present invention apply mutatis mutandis to the secondary particle-based positive electrode active material, for example, Li, M', Si described herein in connection with the positive electrode active material. B , Si A , Zr A、 and Zr BThe various embodiments regarding the identity and amount of are equally applicable to secondary particle-based positive electrode active materials.

[0109] In a further aspect, the present invention provides a single-crystalline particle-based cathode active material for a solid-state battery, comprising Li, M′, and oxygen; where M' is: - Ni with a content x, with 50.0≦x≦95.0 mol% relative to M', - Mn with a content y, where 0.0≦y≦30.0 mol % relative to M', and - a Co content z, with 0.0≦z≦30.0 mol % relative to M′, - a content a of Si, with respect to M' being 0.01≦1.5 mol %; - Zr with a content b, with 0.0≦b≦1.5 mol % relative to M', - D with a content d, where D is an element other than Li, Ni, Mn, Co, Si, Zr and oxygen, and where 0.0≦d≦2.0 mol % relative to M′, Including, - where x, y, z, a, b, and d are measured by ICP-OES, x+y+z+a+b+d is 100.0 mol %, The positive electrode active material has a Si content defined as a / (x+y+z+a+b) A The positive electrode active material has a Si content of Si B and Si B is expressed as mole fraction Si relative to the sum of the mole fractions of Ni, Mn, Co, Si, and Zr, as measured by XPS analysis, and the ratio Si B / Si A A positive electrode active material having a ρ of greater than 50.0 is provided.

[0110] In a highly preferred embodiment of the single-crystal particle-based positive electrode active material, all embodiments directed to the positive electrode active material according to the first aspect of the present invention apply mutatis mutandis to the single-crystal particle-based positive electrode active material. For example, Li, M', Si described herein in the context of the positive electrode active materialB , Si A , Zr A , and Zr B The various embodiments regarding the identity and amount of are equally applicable to single-crystal particle-based positive electrode active materials.

[0111] <Method> In a second aspect, the present invention provides a method for producing a cathode active material, the method comprising: - preparing a slurry containing a lithium transition metal-based oxide compound, a Li source, and an alcohol; - mixing said slurry with a source of Si and optionally with a source of Zr, preferably mixing said slurry with a source of Si and a source of Zr; - Heating the mixture at a temperature of 250°C to less than 500°C for 1 hour to 20 hours to obtain the positive electrode active material.

[0112] In a highly preferred embodiment of the method for producing an active cathode material of the present invention, the active cathode material is according to the first aspect of the present invention. As will be understood by those skilled in the art, when the method for producing an active cathode material of the present invention results in a cathode material according to the first aspect of the present invention, all embodiments directed to the active cathode material according to the first aspect of the present invention apply mutatis mutandis to the method for producing an active cathode material according to the first aspect of the present invention. For example, Li, M', Si as described herein in connection with the active cathode material may be used. B , Si A , Zr A , and Zr B The various embodiments regarding the identity and amount of are equally applicable to the method of preparing the positive electrode active material.

[0113] In a preferred embodiment, the Li source is metallic lithium or a lithium salt, preferably a lithium salt such as LiOH.

[0114] In a preferred embodiment of the method, the lithium transition metal based oxide compound comprises Li, M" and oxygen, where M" comprises Ni, Mn, Co and 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. Preferably, the lithium transition metal based oxide used is or is typically prepared according to a lithiation process, which is a process in which a mixture of a transition metal oxide precursor and a further source of lithium is heated at a temperature of preferably at least 500°C and at most 1000°C. Typically, the transition metal precursor is prepared by co-precipitation of one or more transition metal sources, such as salts, preferably sulfates or nitrates, more preferably sulfates, of the elements Ni, Mn, and / or Co, in the presence of an alkaline compound, such as an alkali hydroxide, e.g., sodium hydroxide and / or ammonia. Preferably, the further source of lithium is metallic lithium or a lithium salt, preferably a lithium salt, such as LiOH.

[0115] In a preferred embodiment, the slurry further contains water. The amount of water in the slurry is preferably 0.5 mol % to 25.0 mol %, more preferably 0.7 mol % to 10.0 mol %, and more preferably 1 mol % to 5 mol %, based on the metal content in the lithium transition metal oxide compound.

[0116] In a preferred embodiment of this method, the source of Zr is a Zr-alkoxide, preferably Zr-ethoxide, Zr-propoxide, or Zr-butoxide, more preferably Zr-propoxide, such as Zr(IV)-propoxide. In a preferred embodiment, the Zr-alkoxide is mixed with the mixture as a solid. Alternatively, more preferably, the Zr-alkoxide is mixed with the slurry as a solution, the solution comprising the Zr-alkoxide and an additional alcohol, the alkoxide group being a conjugate base of the additional alcohol. For example, the Zr-alkoxide is Zr(IV)-propoxide dissolved in propanol. Typically, the solution contains 50 to 90 wt. % Zr-alkoxide, based on the total weight of the solution. Examples of such solutions are 70 wt. % Zr-propoxide in 1-propanol or 80 wt. % Zr-butoxide in 1-butanol. Preferably, the alcohol solvent is methanol, ethanol, propanol, or butanol, preferably ethanol.

[0117] In a preferred embodiment, the amount of Zr present in the Zr source in the slurry is 0.0 mol % to 1.0 mol %, preferably 0.05 mol % to 0.75 mol %, and more preferably 0.1 mol % to 0.5 mol %, based on the metal content in the lithium transition metal oxide compound.

[0118] In a preferred embodiment of the method, the source of Si is a Si-alkoxide, an alkylalkoxysilane, or a polysiloxane, preferably a Si-alkoxide.

[0119] In a more highly preferred embodiment, the source of Si is a Si-alkoxide, preferably SiOR 1 R 2 R 3 R 4 where R 1 , R 2 , R 3 , and R 4are independently selected from H and C1-C8 alkyl or alkenyl optionally substituted with halide, preferably C1-C4 alkyl, more preferably C1-C2 alkyl. In a more preferred embodiment of the method, the source of Si is SiOR4 5 Si alkoxide, wherein R 5 is C1-C8 alkyl or alkenyl, preferably C1-C4 alkyl, more preferably C1-C2 alkyl, optionally substituted with halide. A highly preferred source of Si is silicon tetraethoxide.

[0120] In a preferred embodiment, the source of Si 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 R7 are independently selected from the group consisting of H and C1-C8 alkyl or alkenyl optionally substituted with halide, preferably C1-C4 alkyl, more preferably C1-C2 alkyl, and more preferably R 6 and R 7 are the same alkyl selected from the group consisting of C1-C8 alkyl or alkenyl optionally substituted with halide, preferably C 1~ It is preferably a C4 alkyl, more preferably a C1-C2 alkyl, and most preferably the source of Si is methyltrimethoxysilane.

[0121] In a preferred embodiment, the source of Si is a polysiloxane, preferably a polydialkylsiloxane, where the alkyl group is selected from C1-C8 alkyl or alkenyl, preferably C1-C4 alkyl, more preferably C1-C2 alkyl, optionally substituted with halide, more preferably polydimethylsiloxane. In a highly preferred embodiment, the source of Si is a polysiloxane that is a hydroxy-terminated polydimethylsiloxane or a trimethylsiloxy-terminated polydimethylsiloxane, preferably a hydroxy-terminated polydimethylsiloxane. The present invention provides a method for producing a polysiloxane having a specific number average molecular weight M n The present invention is not limited to a specific polydimethylsiloxane having a number average molecular weight M of 200 g / mol to 1,000,000 g / mol, preferably 300 g / mol to 150,000 g / mol, and most preferably 400 g / mol to 10,000 g / mol, e.g., about 410 g / mol or 4,200 g / mol. Such polymers are commercially available in a variety of different number average molecular weights. Preferably, the hydroxy-terminated polydimethylsiloxane or trimethylsiloxy-terminated polydimethylsiloxane has a number average molecular weight M of 200 g / mol to 1,000,000 g / mol, preferably 300 g / mol to 150,000 g / mol, and most preferably 400 g / mol to 10,000 g / mol, e.g., about 410 g / mol or 4,200 g / mol. n It has.

[0122] A preferred embodiment of the method is heating the mixture under an oxidizing atmosphere, preferably comprising or consisting solely of oxygen, such as air.

[0123] A preferred embodiment of the method involves heating 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 involves heating 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 involves heating the mixture at a temperature of 275° C. to 450° C., preferably 300 to 400° C., more preferably 325 to 375° C.

[0124] A preferred embodiment of the method involves heating the mixture for a period of at least 2 hours, preferably at least 3 hours, more preferably at least 4 hours. A preferred embodiment of the method involves heating for a period of at most 15 hours, preferably at most 10 hours, more preferably at most 7 hours. A preferred embodiment of the method involves heating the mixture for a period of between 2 hours and 15 hours, preferably between 3 hours and 10 hours, more preferably between 4 hours and 7 hours.

[0125] In a preferred embodiment of the method, the mixture heating at a temperature of 275°C to 450°C, preferably 300°C to 400°C, more preferably 325°C to 375°C; and The heating time is 2 to 15 hours, preferably 3 to 10 hours, and more preferably 4 to 7 hours.

[0126] In the most preferred embodiment, the heating occurs in a furnace.

[0127] Certain preferred embodiments of the method include the further step of drying the mixture before heating it, preferably under vacuum, under vacuum heating, or under a constant flow of N2 gas for at least 4 hours and at most 20 hours.

[0128] In certain preferred embodiments of the method, the slurry contains water, as defined herein, and the method further comprises filtering and drying the mixture before heating it. Preferably, the drying is carried out under vacuum, under vacuum heating, or under a constant flow of N2 gas for at least 4 hours and at most 20 hours. As will be understood by those skilled in the art, filtering the mixture can be accomplished by conventional filtering techniques known in the art.

[0129] <Specification by manufacturing method> In a third aspect, the present invention relates to a cathode active material obtainable by the method according to the second aspect of the present invention. As will be understood by those skilled in the art, all embodiments directed to the cathode active material according to the first aspect of the present invention and / or the method according to the second aspect of the present invention apply mutatis mutandis to the cathode active material obtainable by the method according to the present invention. For example, Li, M', Si described herein in the context of the cathode active material may be used. A , Si B , Zr A , Zr B The various embodiments regarding the identity and amount of the source of Zr, and the source of Si are equally applicable to the active cathode material obtained by the method for preparing the active cathode material.

[0130] <Battery> In a fourth aspect, the present invention relates to a battery comprising an active cathode material according to the first aspect of the present invention and / or an active cathode material obtainable by the method according to the third aspect of the present invention.

[0131] In a preferred embodiment, the battery is a solid-state battery. Preferably, the solid-state battery includes a sulfide-based electrolyte. Preferably, the electrolyte is a sulfide-based solid electrolyte, more preferably, the electrolyte includes Li, P, and S. Typically, sulfur-containing compounds of Li6PS5X, where X is F, Cl, Br, or I, preferably, X is Cl, or Br, and thio-LISICON(Li 3.25 Ge 0.25 P 0.75 S4), Li2S-P2S5-LiCl, Li2S-SiS2, LiI-Li2S-SiS2, Li2S-P2S5-LiCl, Li2S-SiS2, LiI-Li 2S-SiS2, LiI-Li2S-P2S5, LiI-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 P1.44 S 11.7 Cl 0.3 , and / or Li7P3S 11 may be suitably used. In a highly preferred embodiment, the battery is a sulfide solid state battery.

[0132] Preferably, the solid-state battery further comprises a positive electrode comprising a positive electrode active material. Suitable electrochemically active positive electrode materials are known in the art. For example, the positive electrode may comprise graphite carbon, metallic lithium, or a metal alloy containing lithium, such as a Li-In alloy, as the positive electrode active material.

[0133] In a preferred embodiment, the 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 will be understood by those skilled in the art, the first discharge capacity (DQ1) is determined by the voltage drop between 4.3 V and 2.5 V (Li / Li + ), or 3.7V to 1.9V (InLi / Li + ) in constant current mode at a C rate of 0.1C.

[0134] In a preferred embodiment, the battery according to the present invention has an efficiency of at least 88%, preferably at least 90%, and more preferably at least 92%. As will be understood by those skilled in the art, the efficiency of a battery is determined by measuring the initial charge capacity (CQ1) and discharge capacity (DQ1) in constant current mode (CC) at a C-rate of 0.1 C at a voltage ranging from 4.3 V to 2.5 V (Li / Li+) or 3.7 V to 1.9 V (In-Li / Li+). The reversible capacity efficiency (%) is obtained according to the following formula:

number

[0135] Preferably, the above schedule uses a 1C current rating of 160mA / g.

[0136] <Use> In a fifth aspect, the present invention relates to the use of an active cathode material according to the first aspect of the invention and / or an active cathode material obtainable by the method according to the third aspect of the invention in a battery.

[0137] A preferred embodiment is the use of a cathode active material in a battery, preferably a solid-state battery, more preferably a sulfide solid-state battery, to increase the efficiency of said battery and / or to increase the first discharge capacity of said battery.

[0138] In a sixth aspect, the present invention relates to the use of a battery according to the present invention in any one of a portable computer, a tablet, a mobile phone, an energy storage system, an electric vehicle, or a hybrid electric vehicle, preferably in an electric vehicle or a hybrid electric vehicle. [Example]

[0139] Experimental Analysis Used in the Examples The following analytical methods are used in the examples.

[0140] A) Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) Measurement 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 spectroscopy (ICP-OES) using an Agilent ICP 720-ES (Agilent Technologies). Two grams of powder sample was dissolved in 10 mL of high-purity hydrochloric acid (at least 37 wt.% HCl based on the total weight of the solution) in an Erlenmeyer flask. The flask was covered with glass and heated on a hot plate at 380 °C until the precursor was completely dissolved. After cooling to room temperature, the solution in the Erlenmeyer flask was poured into a 250 mL volumetric flask. The volumetric flask was then filled with deionized water up to the 250 mL mark, followed by thorough homogenization. Another suitable solvent could be used to completely dissolve the positive electrode active material powder sample.

[0141] B) X-ray photoelectron spectroscopy (XPS) measurement The surface of the positive electrode active material is analyzed using X-ray photoelectron spectroscopy (XPS). In XPS measurements, signals are obtained from the first few nanometers (e.g., 1 nm to 10 nm) of the top, or surface, layer of the sample. Therefore, all elements measured by XPS are contained in the surface layer.

[0142] XPS measurements were performed on the surface of the cathode active material powder particles using a Thermo K-α+ spectrometer. Monochromated Al Kα radiation (hν = 1486.6 eV) was used with a 400 μm spot size and a 45° measurement angle. A wide scan to identify the elements present on the surface was performed with a 200 eV pass energy. The C1s peak with maximum intensity (or center) at a binding energy of 284.8 eV was used as the calibration peak position after data collection. Accurate narrow scans were then performed at 50 eV for at least 10 scans for each identified element to determine the exact surface composition.

[0143] Curve fitting was performed using CasaXPS Version 2.3.19PR1.0 (Casa Software) with Shirley-type background processing and Scofield sensitivity coefficients. Fitting parameters are from Table 2a. The line shape GL(30) is the Gaussian / Lorentzian equation with a 70% Gaussian line and a 30% Lorentzian line. LA(α, β, m) is the asymmetric line shape, where α and β define the tail broadening of the peak and m defines the width.

[0144] [Table 1]

[0145] For the Mn, Co, and Zr peaks, set constraints for each defined peak according to Table 1b.

[0146] [Table 2]

[0147] When measured by XPS, the surface Si content and surface Zr content are expressed as the mole fraction of Si and the mole fraction of Zr in the surface layer of a particle divided by the total content of Ni, Co, Mn, Si, and Zr in said surface layer, and are calculated as follows:

[0148]

number

[0149]

number

[0150] The XPS peak position information can be easily obtained in the area and component report specifications after fitting. The XPS graphs of Si and Zr for EX1.1 are shown in Figure 1.

[0151] C) Carbon analysis The carbon content of the cathode active material powder is measured using a Horiba Emia-Expert carbon / sulfur analyzer. One gram of cathode active material powder is placed in a ceramic crucible in a high-frequency induction furnace. 1.5 grams of tungsten and 0.2 grams of tin are added to the crucible as promoters. The powder is heated at a programmable temperature, and the gases produced during combustion are then analyzed by an infrared detector. Analysis of CO2 and CO determines the carbon concentration.

[0152] D) Sulfide Solid State Rechargeable Battery Testing D-1) Preparation of sulfide solid state rechargeable battery Preparation of the positive electrode: For the preparation of the positive electrode, a slurry containing the positive electrode active material powder, Li-PS-based solid electrolyte, carbon (Super-P, Timcal), and binder (RC-10, Arkema) in a butyl acetate solvent in a ratio of 64.0:30.0:3.0:3.0 by weight was mixed in an Ar-filled glove box. The slurry was cast onto one side of an aluminum foil, and the slurry-coated foil was then dried in a vacuum oven to obtain the positive electrode. The resulting positive electrode was punched to a diameter of 10 nm, with an active material loading of approximately 4 mg / cm. 2 is.

[0153] Preparation of the negative electrode: To prepare the negative electrode, a Li foil (3 mm diameter, 100 μm thickness) is centered on top of an In foil (10 nm diameter, 100 μm thickness) and pressed together to form a Li—In alloy negative electrode.

[0154] Preparation of the separator: For the preparation of a separator that also functions as a solid electrolyte in a battery, the Li-PS based solid electrolyte is pelletized under a pressure of 250 MPa to obtain a pellet thickness of 100 μm.

[0155] Cell assembly: The sulfide solid-state rechargeable battery is assembled in an Ar-filled glove box in the following order from bottom to top: cathode with Al current collector with coated parts on top - separator - anode with Li side on top - Cu current collector. The stacked components are pressed together with a pressure of 250 MPa and placed in an external cage to prevent air exposure.

[0156] D-2) Test method The test method is a conventional "constant cutoff voltage" test. Conventional cell testing of the present invention follows the schedule shown in Table 2. Each cell is cycled at 60°C using a Toscat-3100 computer-controlled galvanostatic cycling station (manufactured by Toyo).

[0157] The above schedule uses a 1C current rating of 160mA / g. The initial charge capacity (CQ1) and discharge capacity (DQ1) are measured from 4.3V to 2.5V (Li / Li + ), or 3.7V~1.9V(In-Li / Li + ) at a C-rate of 0.1 C in constant current mode (CC). The reversible capacity efficiency (%) is obtained according to the following formula:

number

[0158] The present invention is further illustrated in the following examples.

[0159] Comparative Example 1 The positive electrode active material CEX1 can be obtained by the following steps: 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 uniformly to obtain a mixture.

[0160] 2) First heating: The mixture prepared from step 1) is heated at 830°C for 10 hours under an O2 atmosphere and cooled to room temperature.

[0161] 3) Preparation of metal solution: 1.01 grams of zirconium (IV) propoxide (70.0 wt. % Zr-propoxide in n-propanol solution) is dissolved in 3 grams of ethanol.

[0162] 4) Preparation of 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 homogeneously to obtain a slurry.

[0163] 5) Preparation of wet mixture: The metal solution prepared from step 3) and the slurry prepared from step 4) are mixed and stirred for 15 hours, and then filtered.

[0164] 6) Second heating: The wet mixture prepared from step 5) is heated at 350°C for 5 hours under an O2 atmosphere at a heating rate of 5°C / min. The second heated material is cooled to room temperature, crushed, and sieved to obtain the positive electrode active material CEX1.

[0165] Example 1.1 The positive electrode active material EX1.1 can be obtained by the following steps: 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 uniformly to obtain a mixture.

[0166] 2) First heating: The mixture prepared from step 1) is heated at 830°C under an O2 atmosphere for 10 hours and cooled to room temperature.

[0167] 3) Preparation of metal solution: 0.76 grams of zirconium(IV) propoxide (70.0 wt. % Zr-propoxide in n-propanol solution) and 0.11 grams of silicon tetraethoxide are dissolved in 3 grams of ethanol.

[0168] 4) Preparation of 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 homogeneously to obtain a slurry.

[0169] 5) Preparation of wet mixture: The metal solution prepared from step 3) and the slurry prepared from step 4) are mixed, stirred for 15 hours, and then filtered.

[0170] 6) Second heating: The wet mixture prepared from step 5) is heated at 350°C for 5 hours under an O2 atmosphere at a heating rate of 5°C / min. The second heated material is cooled to room temperature, crushed and sieved to obtain positive electrode active material EX1.1.

[0171] Example 1.2 Positive electrode active material EX1.2 is prepared according to the same method as EX1.1, except that in step 3), 0.51 grams of zirconium(IV) propoxide and 0.22 grams of silicon tetraethoxide are used to prepare the metal solution.

[0172] Example 1.3 Positive electrode active material EX1.3 is prepared according to the same method as EX1.1, except that in step 3), 0.45 grams of silicon tetraethoxide is used to prepare the metal solution.

[0173] Example 2.1 The positive electrode active material 2.1 can be obtained by the following steps: 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 uniformly to obtain a mixture.

[0174] 2) First heating: The mixture prepared from step 1) is heated at 830°C under an O2 atmosphere for 10 hours and cooled to room temperature.

[0175] 3) Preparation of metal solution: 0.51 grams of zirconium(IV) propoxide (70.0 wt. % Zr-propoxide in n-propanol solution) and 0.22 grams of silicon tetraethoxide are dissolved in 3 grams of ethanol.

[0176] 4) Preparation of slurry: 70.00 grams of the first heated material, 26.00 grams of ethanol, and 0.10 grams of LiOH are mixed uniformly to obtain a slurry.

[0177] 5) Preparation of the second mixture: The metal solution prepared in step 3) and the slurry prepared in step 4) are mixed and stirred for 15 hours. The mixed slurry is evaporated to obtain the second mixture.

[0178] 6) Second heating: The second mixture prepared from step 5) is heated at 350°C for 5 hours under an O2 atmosphere at a heating rate of 5°C / min. The second heated material is cooled to room temperature, crushed, and sieved to obtain positive electrode active material EX2.1.

[0179] Example 2.2 Positive electrode active material EX2.2 is prepared according to the same method as EX2.1, except that in step 3), 0.45 grams of silicon tetraethoxide is used to prepare the metal solution.

[0180] Comparative Example 2 The positive electrode active material CEX2 can be obtained by the following steps: 1) First mixture: 100.00 grams Ni 0.64 Co 0.20 Mn 0.16 (OH)2, and 26.77 grams of anhydrous LiOH are mixed uniformly to obtain a first mixture.

[0181] 2) First heating: The first mixture prepared from step 1) is heated at 830°C for 10 hours under an O2 atmosphere and cooled to room temperature.

[0182] 3) Second mixing: 100.00 grams of the first heated material and 0.19 grams of SiO2 are mixed uniformly to obtain a second mixture.

[0183] 4) Second heating: The second mixture prepared from step 2) is heated at a heating rate of 5°C / min until it reaches 350°C, and then at a heating rate of 2°C / min until it reaches 700°C, and then at 700°C for 10 hours. The second heated material is cooled to room temperature, crushed, and sieved to obtain the positive electrode active material CEX2.

[0184] Comparative Example 3.1 The positive electrode active material CEX3.1 can be obtained by the following steps: 1) First mixture: 100.00 grams Ni0.64 Co 0.20 Mn 0.16 (OH)2, and 26.77 grams of anhydrous LiOH are mixed uniformly to obtain a first mixture.

[0185] 2) First heating: The first mixture prepared from step 1) is heated at 830°C for 10 hours under an O2 atmosphere and cooled to room temperature.

[0186] 3) Second Mixing: 100.00 grams of the first heating material and 0.77 grams of ZrO2 are mixed uniformly to obtain a second mixture.

[0187] 4) Second heating: The second mixture prepared from step 2) is heated at 850°C for 6 hours and cooled to room temperature. The cooled material is crushed and sieved to obtain the cathode active material CEX3.1.

[0188] Comparative Example 3.2 Positive electrode active material CEX3.2 is prepared according to the same method as CEX3.1, except that in step 3), 0.30 grams of LiOH is added during the second mixing to prepare the second mixture.

[0189] [Table 3]

[0190] [Table 4]

[0191] Table 3 shows the chemical composition, Si, of all the examples and comparative examples. B / Si A ratio, and Zr B / Zr A , and carbon content. Table 4 summarizes the electrochemical properties, such as the initial discharge capacity DQ1 and efficiency, of the examples and comparative examples.

[0192] Table 3 shows the Si(Si B ) and Zr(Zr B ) XPS analysis results for CEX1, EX1.1, EX1.2, EX1.3, EX2.1, and EX2.2 are shown in Table 1. A ) and Zr(Zr A ) and compare with the ICP-OES results. B or Zr B A result of σ higher than 0 indicates that the Si or Zr is present on the surface of the positive electrode active material, which is related to XPS measurements where the signal is acquired from the first few nanometers (e.g., 1 nm to 10 nm) of the top of the sample. On the other hand, the Si A and Zr A are the Si and Zr contents of the whole particle. Therefore, Si content higher than 1 B / Si A and Zr B / Zr A The ratio of the XPS results to the ICP-OES results, such as , indicates that the Si and Zr are mainly present on the surface of the positive electrode active material. B / Si A Value or Zr B / Zr A The values ​​correspond to the presence of more Si or Zr on the surface of the cathode active material. A representative XPS spectrum showing the Si and Zr peaks of EX1.1 is in Figure 1.

[0193] 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. B / Si A value and Zr B / Zr AThe values ​​were 360.0 and 306.7, respectively, confirming 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% Zr, but no Si, relative to the total molar content of Ni, Mn, Co, Si, and Zr. The solid-state rechargeable battery containing EX1.1 has a DQ1 value of 190.6 mAh / g, which is higher than the DQ1 value of 174.6 mAh / g of the battery containing CEX1. Furthermore, 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% Si and 0.15 mol% 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 The values ​​are 346.7 and 266.7, respectively, and the Zr B / Zr A The DQ1 values ​​were 280.0 and 186.7, respectively, confirming the presence of Si and Zr on the surface of EX1.2 and EX2.1 according to the present invention. The DQ1 value and efficiency of the battery containing EX1.2 were 183.7 mAh / g and 90.4%, respectively, and the DQ1 value and efficiency of the battery containing EX2.1 were 192.5 mAh / g and 90.6%, respectively. The DQ1 values ​​and efficiencies of the batteries containing EX1.2 or EX2.1 were higher than those of the batteries containing CEX1, indicating that the batteries containing EX1.2 or EX2.1 have higher initial capacities and improved electrochemical stability.

[0194] Both positive electrode active materials EX1.3 and EX2.2 contain 0.30 mol % 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, which is higher than the DQ1 value of the battery containing CEX1, and the efficiency is 88.3%, which is similar to the efficiency 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 improvements over the battery containing CEX1.

[0195] The positive electrode active material CEX2 contains 0.28 mol% Si relative to the total molar content of Ni, Mn, Co, Si, and Zr analyzed by ICP-OES, which is a similar Si content to EX2.2. B / Si A The value is 272.8, and the Si of EX2.2 B / Si A The value was 253.3, CEX2 was prepared by dry mixing with SiO2, and EX2.2 was obtained by mixing with a slurry containing a Si-containing solution.

[0196] The presence of Si on the surface of the particles, optionally with the presence of Zr, is higher than 50.0 B / Si A In particular, it has been clearly observed that the present invention can achieve the object of the present invention, which is to provide a positive electrode active material having improved first discharge capacity and improved efficiency, by preparing a slurry containing a lithium transition metal oxide, Li, and an alcohol by mixing the slurry with a Si-containing solution.

Claims

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

2. 2. The positive electrode active material according to claim 1, wherein 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 %, relative to M'.

3. The positive electrode active material has a Zr content Zr defined as b / (x+y+z+a+b) Ａ and The positive electrode active material has a Zr content of Zr Ｂ and Zr Ｂ is expressed as mole fraction Zr relative to the sum of mole fractions of Ni, Mn, Co, Si, and Zr, as measured by XPS analysis, and the ratio Zr Ｂ / Zr Ａ The positive electrode active material according to claim 1 or 2, wherein is greater than 50.0 (greater than 50).

4. Si Ｂ / Si Ａ is greater than 100.0 (greater than 100), and Zr Ｂ / Zr Ａ The positive electrode active material according to any one of claims 1 to 3, wherein is greater than 100.0 (greater than 100).

5. 5. The positive electrode active material according to claim 1, wherein, with respect to M', 55.0≦x≦90.0 mol %, preferably 58.0≦x≦88.0, more preferably 60.0≦x≦85.

0.

6. 6. The positive electrode active material according to claim 1, wherein 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%, relative to M'.

7. 7. The positive electrode active material according to claim 1, wherein D is at least one element selected from the group consisting of Al, B, Ba, Ca, 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, and more preferably Al, B, Ti, Nb, and W.

8. The positive electrode active material according to any one of claims 1 to 7, comprising polycrystalline particles.

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

10. A method for producing a cathode active material, preferably the cathode active material according to any one of claims 1 to 9, said method comprising the steps of: - preparing a slurry containing a lithium transition metal based oxide compound, a Li source, and an alcohol; - mixing said slurry with a source of Si, and optionally with a source of Zr; heating the mixture at a temperature of from 250° C. to less than 500° C. for a period of from 1 hour to 20 hours to obtain the cathode active material.

11. The method of claim 10, further comprising mixing the slurry with a source of Si and a source of Zr, wherein the source of Zr is a Zr-alkoxide.

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

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

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

15. 15. Use of the solid state battery of claim 13 or 14 in any one of a portable computer, a tablet, a mobile phone, an energy storage system, an electric vehicle, or a hybrid electric vehicle.

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