Positive electrode active material and method for producing the positive electrode active material

Abstract

The present invention relates to a cathode active material for a solid-state battery, comprising lithium, oxygen, nickel, and at least one metal selected from the group consisting of manganese and cobalt, wherein the cathode active material has a silicon-rich amount in a surface layer, and the cathode active material comprises single-crystal particles. The inventors have surprisingly found that the cathode active material of the present invention improves the storage stability of the cathode active material. In particular, by applying a silicon surface layer on the cathode active material, a reduction in water and carbon (or carbon dioxide) uptake is observed. Furthermore, the cathode active material improves the electrochemical stability of the battery.

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. 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. Among these, lithium secondary batteries have come into the spotlight 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] Doo et al. (ACS Appl. Energy Mater. 2019, 2, 6246-6253) synthesized polycrystalline LiNi 0.8 Co 0.1 Mn 0.1 with polydimethylsiloxane and then heated at 230° C., thereby improving the electrochemical stability of the Ni-rich oxide material.

[0007] However, there remains a need to provide positive electrode active materials with improved storage stability and / or improved electrochemical stability. [Prior art documents] [Non-patent literature]

[0008] [Non-Patent Document 1] Doo,“ACS Appl.Energy Mater.”,2019,2,p.6246-6253 Summary of the Invention [Problem to be solved by the invention]

[0009] An object of the present invention is to provide a positive electrode active material containing Si to improve the storage stability and / or electrochemical stability of the positive electrode active material.

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

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

[0012] Another object of the present invention is to provide a use of said battery. [Means for solving the problem]

[0013] In a first aspect, the object of the present invention is to provide an active cathode material for a rechargeable battery, comprising lithium, oxygen, nickel, and manganese, and at least one metal selected from the group consisting of manganese and cobalt, The positive electrode active material has a rich amount of Si in the surface layer, The positive electrode active material is achieved by providing a positive electrode active material that includes single crystal particles.

[0014] In other words, the positive electrode active material of the present invention has a surface layer containing Si.

[0015] The present inventors have surprisingly found that the cathode active material of the present invention improves the storage stability of the cathode active material. In particular, as shown in the accompanying examples, by applying a surface layer of Si to the cathode active material, a reduction in the uptake of water and carbon (or carbon dioxide) is observed. Furthermore, the cathode active material has a low Q total As shown by the values, the electrochemical stability of batteries, particularly polymer solid state batteries, is improved, which indicates high stability of the positive electrode active material powder during high temperature operation. Furthermore, the positive electrode active material improves the efficiency of batteries, particularly sulfide solid state batteries.

[0016] Without wishing to be bound by any theory, the inventors believe that the surface layer of Si acts as a hydrophobic surface layer, inhibiting the formation of residual lithium compounds such as Li2CO3, which are formed by reaction between lithium present in the active cathode material and water and carbon in the surrounding air because the hydrophobic surface inhibits contact between water and the active cathode material.

[0017] In a further aspect, the present invention provides a method for producing the cathode active material.

[0018] In a further aspect, the present invention provides a battery comprising the above-described active cathode material.

[0019] In a further aspect, the present invention provides the use of the battery. [Brief explanation of the drawings]

[0020] [Figure 1] This is the XPS peak of Si2p in EX2.1. DETAILED DESCRIPTION OF THE INVENTION

[0021] In the following detailed description, preferred embodiments are described in detail to enable the practice of the invention. While the invention is described with reference to these 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 light of the following detailed description and the accompanying drawings.

[0022] When used in this 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 of."

[0023] 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.

[0024] 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 it is a material that can capture Li ions and release them when subjected to a voltage change over a predetermined period of time.

[0025] As used herein, the term "cathode" is defined as a material that includes a cathode active material in addition to other components that are not electrochemically active, particularly a conductive agent such as carbon black, or a binder such as PVDF.

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

[0027] In the context of the present invention, the carbon content and moisture content (or water content) after exposure are 2 The temperature is measured by an exposure test performed by evenly spreading 40 grams of the positive electrode active material on a plate and placing the plate in a chamber at 30° C. The atmosphere of the chamber is controlled to have a relative humidity level of 50%.

[0028] [Cathode active material] In a first aspect, the present invention provides a cathode active material for a solid-state battery, comprising lithium, oxygen, nickel, and at least one metal selected from the group consisting of manganese and cobalt, the cathode active material comprising: The positive electrode active material has a Si content B Further containing silicon, Si B is expressed as mole fraction Si relative to the sum of the mole fractions of Ni, Mn, Co, and Si, as measured by XPS analysis, Si B is greater than 0.05, The positive electrode active material relates to a positive electrode active material containing single crystal particles.

[0029] A preferred embodiment is a cathode active material of the present invention having a carbon content of greater than 150 ppm, preferably greater than 250 ppm, and more preferably greater than 300 ppm, based on the total weight of the cathode active material. A preferred embodiment is a cathode active material of the present invention having a carbon content of less than 2000 ppm, preferably less than 1850 ppm, and more preferably less than 1700 ppm, based on the total weight of the cathode active material. A preferred embodiment is a cathode active material of the present invention having a carbon content in the range of 150 ppm to 2000 ppm, preferably 250 ppm to 1850 ppm, and more preferably 300 ppm to 1700 ppm, based on the total weight of the cathode active material. A particularly preferred embodiment is a cathode active material of the present invention having a carbon content of greater than 500 ppm, preferably greater than 1000 ppm, and more preferably greater than 1200 ppm, based on the total weight of the cathode active material. A particularly preferred embodiment is a cathode active material of the present invention having a carbon content of less than 2000 ppm, less than 1850 ppm, and more preferably less than 1700 ppm, based on the total weight of the cathode active material. A particularly preferred embodiment is a cathode active material of the present invention having a carbon content in the range of 500 ppm to 2000 ppm, preferably in the range of 1000 ppm to 1850 ppm, and more preferably in the range of 1200 ppm to 1700 ppm, based on the total weight of the cathode active material. Furthermore, the carbon content of the cathode active material of the present invention reported above is measured before the exposure test. 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 using a carbon analyzer. For example, but not limited to, the carbon content can be measured using a Horiba Emia-Expert carbon / sulfur analyzer.

[0030] In a preferred embodiment of the present invention, the active cathode material of the present invention has a carbon incorporation of less than 1500 ppm carbon by total weight of the active cathode material, preferably less than 1200 ppm carbon, and more preferably less than 1000 ppm carbon by total weight of the active cathode material. As will be understood by those skilled in the art, carbon incorporation is measured after exposure testing.

[0031] A preferred embodiment is a cathode active material of the present invention having a water content of greater than 10 ppm, preferably greater than 25 ppm, and more preferably greater than 50 ppm, by total weight of the cathode active material. A preferred embodiment is a cathode active material of the present invention having a water content of less than 1200 ppm, preferably less than 1000 ppm, and more preferably less than 500 ppm, by total weight of the cathode active material. A preferred embodiment is a cathode active material of the present invention having a water content in the range of 10 ppm to 1200 ppm, preferably 25 ppm to 1000 ppm, and more preferably 50 ppm to 500 ppm, by total weight of the cathode active material. As will be understood by those skilled in the art, water content or moisture content is measured using a Karl Metrohm Fischer Coulometer. Additionally, the above-reported water content of the positive electrode active materials of the present invention is measured prior to the exposure test.

[0032] In a preferred embodiment of the present invention, the cathode active material of the present invention has a water uptake of less than 1500 ppm by total weight of the cathode active material, preferably less than 1000 ppm by total weight of the cathode active material, and more preferably less than 500 ppm by total weight of the cathode active material. As will be understood by those skilled in the art, water uptake is measured after exposure testing.

[0033] A preferred embodiment is a positive electrode active material of the present invention containing Li, Ni, Mn, Co, and oxygen, wherein the Ni content is x, and the Ni content satisfies 50.0≦x≦98.0 mol% relative to the total of Ni, Mn, and Co. A more preferred embodiment is a positive electrode active material of the present invention, wherein the Ni content is x, and the Ni content satisfies x≧55.0 mol%, preferably x≧58.0 mol%, and more preferably x≧60.0 mol% relative to the total of Ni, Mn, and Co. In a preferred embodiment, the Ni content is x, and the Ni content satisfies x≦90.0 mol%, preferably x≦88 mol%, and more preferably x≦85.0 mol% relative to the total of Ni, Mn, and Co. In a more preferred embodiment, the positive electrode active material of the present invention has a Ni content of x, which 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%, with respect to the total of Ni, Mn, and Co.

[0034] A particularly preferred embodiment is a positive electrode active material of the present invention comprising Li, Ni, Mn, Co, and oxygen, wherein M' comprises Ni, and the Ni content is x, where x is 55.0 mol %, preferably x 58.0 mol %, and more preferably x 60.0 mol %, relative to the total of Ni, Mn, and Co. In a particularly preferred embodiment, the Ni content is x, where x is 75.0 mol %, preferably x 72 mol %, and more preferably x 70.0 mol % relative to the total of Ni, Mn, and Co. A more particularly preferred embodiment is a positive electrode active material of the present invention, where the Ni content is x, where x is 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 % relative to the total of Ni, Mn, and Co.

[0035] A specific preferred embodiment is the positive electrode active material of the present invention containing Li, Ni, Mn, Co, and oxygen, where Ni has a content of x, and x ≥ 75.0 mol%, preferably x ≥ 78.0 mol%, more preferably x ≥ 80.0 mol% with respect to the total of Ni, Mn, and Co. In a specific preferred embodiment, Ni has a content of x, and x ≤ 92.0 mol%, preferably x ≤ 90 mol%, more preferably x ≤ 88.0 mol% with respect to the total of Ni, Mn, and Co. A more specific preferred embodiment is the positive electrode active material of the present invention, where Ni has a content of x, and 75.0 mol% ≤ x ≤ 92.0 mol%, preferably 78.0 mol% ≤ x ≤ 90.0 mol%, more preferably 80.0 mol% ≤ x ≤ 88.0 mol% with respect to the total of Ni, Mn, and Co.

[0036] A preferred embodiment is the positive electrode active material of the present invention containing Li, Ni, Mn, Co, and oxygen, where Mn has a content of y, and 0.0 ≤ y ≤ 30.0 mol% with respect to the total of Ni, Mn, and Co. A more preferred embodiment is the positive electrode active material of the present invention, where Mn has a content of y, and y > 0.0 mol%, preferably y ≥ 1.0 mol%, more preferably y ≥ 2.0 mol% with respect to the total of Ni, Mn, and Co. In a more preferred embodiment, the content is y ≤ 20.0 mol%, preferably y ≤ 15.0 mol%, more preferably y ≤ 10.0 mol% with respect to the total of Ni, Mn, and Co. In a more preferred embodiment, Mn has a content of y, and 0.0 mol% < y ≤ 20.0 mol%, preferably 1.0 mol% ≤ y ≤ 15.0 mol%, more preferably 2.0 mol% ≤ y ≤ 10.0 mol% with respect to the total of Ni, Mn, and Co.

[0037] A specific preferred embodiment is the cathode active material of the present invention containing Li, Ni, Mn, Co, and oxygen. Mn has a content of y, and y > 0.0 mol%, preferably y ≥ 5.0 mol%, more preferably y ≥ 10.0 mol% with respect to the total of Ni, Mn, and Co. In a specific preferred embodiment, the content is y ≤ 30.0 mol%, preferably y ≤ 25.0 mol%, more preferably y ≤ 20.0 mol% with respect to the total of Ni, Mn, and Co. In a specific preferred embodiment, Mn has a content of y, and 0.0 mol% < y ≤ 30.0 mol%, preferably 5.0 mol% ≤ y ≤ 25.0 mol%, more preferably 10.0 mol% ≤ y ≤ 20.0 mol% with respect to the total of Ni, Mn, and Co.

[0038] A preferred embodiment is the cathode active material of the present invention containing Li, Ni, Mn, Co and oxygen. Co has a content of z, and 0.0 ≤ z ≤ 30.0 mol% with respect to the total of Ni, Mn, and Co. In a more preferred embodiment, Co has a content of x, and z > 0.0 mol%, preferably z ≥ 1.0 mol%, more preferably z ≥ 2.0 mol% with respect to the total of Ni, Mn, and Co. In a preferred embodiment, the content is z ≤ 20.0 mol%, preferably z ≤ 15.0 mol%, more preferably z ≤ 10.0 mol% with respect to the total of Ni, Mn, and Co. In a preferred embodiment, Co has a content of z, and 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 the total of Ni, Mn, and Co.

[0039] A specific preferred embodiment is the positive electrode active material of the present invention containing Li, Ni, Mn, Co, and oxygen, where Co has a content z, and z > 0.0 mol%, preferably z ≥ 5.0 mol%, more preferably z ≥ 10.0 mol% with respect to the total of Ni, Mn, and Co. In a preferred embodiment, the content is z ≤ 30.0 mol%, preferably z ≤ 25.0 mol%, more preferably z ≤ 20.0 mol% with respect to the total of Ni, Mn, and Co. In a preferred embodiment, Co has a content z, and 0.0 mol% < z ≤ 30.0 mol%, preferably 5.0 mol% ≤ z ≤ 25.0 mol%, more preferably 10.0 mol% ≤ z ≤ 20.0 mol% with respect to the total of Ni, Mn, and Co.

[0040] A very preferred embodiment is the positive electrode active material of the present invention containing Li, Ni, Mn, Co, and oxygen, - Ni with a content x, where 50.0 ≤ x ≤ 98.0 mol% with respect to the total of Ni, Mn, and Co, - Mn with a content y, where 0.0 ≤ y ≤ 30.0 mol% with respect to the total of Ni, Mn, and Co, - Co with a content z, where 0.0 ≤ z ≤ 30.0 mol% with respect to the total of Ni, Mn, and Co, and - where x, y, and z are the positive electrode active material measured by ICP - OES.

[0041] As understood by those skilled in the art, the amounts of Li, Ni, Mn, and Co in the positive electrode active material are measured by inductively coupled plasma optical emission spectrometry (ICP - OES). For example, without limitation to the present invention, Agilent ICP 720 - ES is used for ICP - OES analysis.

[0042] A very preferred embodiment is the positive electrode active material of the present invention containing Li, M', and oxygen, where M' is - Ni with a content of x, where 55.0 mol% ≤ x ≤ 90.0 mol%, preferably 58.0 mol% ≤ x ≤ 88.0 mol%, more preferably 60.0 mol% ≤ x ≤ 85.0 mol% with respect to the total of Ni, Mn, and Co, Ni, and - Mn with a content of y, where 0.0 mol% < y ≤ 20.0 mol%, preferably 1.0 mol% ≤ y ≤ 15.0 mol%, more preferably 2.0 mol% ≤ y ≤ 10.0 mol% with respect to the total of Ni, Mn, and Co, Mn, and - Co with a content of z, where 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 the total of Ni, Mn, and Co, Co, and which contains - wherein x, y, and z are the cathode active material measured by ICP - OES.

[0043] A very preferred embodiment is the cathode active material of the present invention containing Li, M', and oxygen, where M' is - Ni with a content of x', where 50.0 ≤ x' ≤ 98.0 mol% with respect to M', Ni, and - Mn with a content of y', where 0.0 ≤ y' ≤ 30.0 mol% with respect to M', Mn, and - Co with a content of z', where 0.0 ≤ z' ≤ 30.0 mol% with respect to M', Co, and - Si with a content of a', where 0.0 < a' ≤ 5.0 mol% with respect to M', Si, and - D with a content of d', where in the formula, D is an element other than Li, Ni, Mn, Co, Si, and oxygen, and 0.0 ≤ d' ≤ 2.0 mol% with respect to M', D, and which contains - wherein x', y', z', a' and d' are measured by ICP - OES, - and x'+y'+z'+a'+d' is 100.0 mol%, the cathode active material.

[0044] As will be understood by those skilled in the art, the amounts of Li and M', preferably Li, Ni, Mn, Co, D, and Si, 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.

[0045] A more preferred embodiment is a positive electrode active material of the present invention comprising Li, M', and oxygen, wherein M' is Ni with a content x', where x' is 55.0 mol% or more, preferably x' 58.0 mol% or more, and more preferably x' 60.0 mol% or more, relative to M'. In a preferred embodiment, the Ni content x' is 90.0 mol% or less, preferably x' 88 mol% or less, and more preferably x' 85.0 mol% or less, relative to M'. A more preferred embodiment is a positive electrode active material of the present invention, wherein the Ni content x' is 55.0 mol% or less x' 90.0 mol%, preferably 58.0 mol% or less x' 88.0 mol%, and more preferably 60.0 mol% or less x' 85.0 mol% relative to M'.

[0046] A particularly preferred embodiment is a positive electrode active material of the present invention comprising Li, M', and oxygen, wherein M' is Ni with a content x', where x' is 55.0 mol% or more, preferably x' 58.0 mol% or more, and more preferably x' 60.0 mol% or more, relative to M'. In a particularly preferred embodiment, the Ni content x' is 75.0 mol% or less, preferably x' 72 mol% or less, and more preferably x' 70.0 mol% or less, relative to M'. A more particularly preferred embodiment is a positive electrode active material of the present invention, wherein the Ni content x' is 55.0 mol% or less x' 75.0 mol%, preferably 58.0 mol% or less x' 72.0 mol%, and more preferably 60.0 mol% or less x' 70.0 mol% relative to M'.

[0047] A specific preferred embodiment is a positive electrode active material of the present invention containing Li, M', and oxygen, where M' is Ni with a content x', and for M', x' ≥ 75.0 mol%, preferably x' ≥ 78.0 mol%, more preferably x' ≥ 80.0 mol%. It is a positive electrode active material containing Ni. In a specific preferred embodiment, for Ni, the content x' is such that x' ≤ 92.0 mol% with respect to M', preferably x' ≤ 90 mol%, more preferably x' ≤ 88.0 mol%. A more specific preferred embodiment is a positive electrode active material of the present invention, where for Ni, the content x' is such that 75.0 mol% ≤ x' ≤ 92.0 mol% with respect to M', preferably 78.0 mol% ≤ x' ≤ 90.0 mol%, more preferably 80.0 mol% ≤ x' ≤ 88.0 mol%.

[0048] A more preferred embodiment is a positive electrode active material of the present invention containing Li, M', and oxygen, where M' is Mn with a content y', and for M', y' > 0.0 mol%, preferably y' ≥ 1.0 mol%, more preferably y' ≥ 2.0 mol%. It is a positive electrode active material containing Mn. In a more preferred embodiment, the content is such that y' ≤ 20.0 mol% with respect to M', preferably y' ≤ 15.0 mol%, more preferably y' ≤ 10.0 mol%. In a more preferred embodiment, for Mn, the content y' is such that 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%.

[0049] A specific preferred embodiment is a positive electrode active material of the present invention containing Li, M', and oxygen, where M' is Mn with a content y', and for M', y' > 0.0 mol%, preferably y' ≥ 5.0 mol%, more preferably y' ≥ 10.0 mol%. It is a positive electrode active material containing Mn. In a specific preferred embodiment, the content is y' ≤ 30.0 mol%, preferably y' ≤ 25.0 mol%, more preferably y' ≤ 20.0 mol% for M'. In a specific preferred embodiment, Mn has a content y' such that 0.0 mol% < y' ≤ 30.0 mol%, preferably 5.0 mol% ≤ y' ≤ 25.0 mol%, more preferably 10.0 mol% ≤ y' ≤ 20.0 mol% for M'.

[0050] A more preferred embodiment is a positive electrode active material of the present invention containing Li, M', and oxygen, where M' is Co with a content z', and for M', z' > 0.0 mol%, preferably z' ≥ 1.0 mol%, more preferably z' ≥ 2.0 mol%. It is a positive electrode active material containing Co. In a preferred embodiment, the content is z' ≤ 20.0 mol%, preferably z' ≤ 15.0 mol%, more preferably z' ≤ 10.0 mol% for M'. In a preferred embodiment, Co has a content z' such that 0.0 mol% < z' ≤ 20.0 mol%, preferably 1.0 mol% ≤ z' ≤ 15.0 mol%, more preferably 2.0 mol% ≤ z' ≤ 10.0 mol% for M'.

[0051] A specific preferred embodiment is a positive electrode active material of the present invention containing Li, M', and oxygen, where M' is Co with a content z', and for M', z' > 0.0 mol%, preferably z' ≥ 5.0 mol%, more preferably z' ≥ 10.0 mol%. It is a positive electrode active material containing Co. In a preferred embodiment, the content is z' ≤ 30.0 mol%, preferably z' ≤ 25.0 mol%, more preferably z' ≤

[0052] 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 an entire positive electrode active material containing one or more elements other than Li, Ni, Mn, Co, Si, and O, which are reflected in the parameter "D" used herein. A preferred embodiment is a positive electrode active material according to the present invention containing D, where D is selected from the group consisting of Al, B, Ba, Ca, Ce, Cr, Fe, La, Mg, Mo, Nb, S, Sr, Ti, V, W, Y, Zr, and Zn, preferably Al, B, Ti, Cr, Nb, S, Y, and W, more preferably at least one element selected from the group consisting of Al, B, Ti, Nb, and W.

[0053] A preferred embodiment is a positive electrode active material according to the present invention containing Li, M', and oxygen, where M' is D with a content d', and for M', d'>0.0 mol%, preferably d'≥0.25 mol%, more preferably d'≥0.5 mol%. It is a positive electrode active material containing D. In a preferred embodiment, the content d' is d'≤1.75 mol% with respect to M', preferably d'≤1.5 mol%, more preferably d'≤1.25 mol%. In a preferred embodiment, the content d is 0.0 mol%<d'≤1.75 mol% with respect to M', preferably 0.25 mol%≤d'≤1.5 mol%, more preferably 0.5 mol%≤d'≤1.25 mol%.

[0054] In a specific preferred embodiment, the positive electrode active material has d' = 0.0 mol% with respect to M' according to the present invention.

[0055] A preferred embodiment is a positive electrode active material according to the present invention containing Li, M', and oxygen, where M' is Si with a content a', a' > 0.01 mol%, preferably a' ≥ 0.05 mol%, more preferably a' ≥ 0.1 mol%, and the positive electrode active material contains Si. In a preferred embodiment, the content a' is a' ≤ 2.0 mol%, preferably a' ≤ 1.0 mol%, more preferably a' ≤ 0.8 mol% with respect to M'. In a preferred embodiment, the content a' is 0.01 mol% < a' ≤ 2.0 mol%, preferably 0.05 mol% ≤ a' ≤ 1.0 mol%, more preferably 0.1 mol% ≤ a' ≤ 0.8 mol% with respect to M'.

[0056] A preferred embodiment is a 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 0.92, more preferably greater than 0.95. A preferred embodiment is a 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 a 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).

[0057] A highly preferred embodiment is a positive electrode active material according to the present invention having the formula (I): Li w2 [[ID=!2]]Ni x2 Mn y2 Co z2 Si a2 D2 d2 O2(I) where 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, and 0.0 < z2 ≤ 0.30, preferably 0.05 ≤ z2 ≤ 0.25, more preferably 0.10 ≤ z2 ≤ 0.20, and 0.0001 ≤ a2 ≤ 0.02, preferably 0.0005 ≤ a2 ≤ 0.01, more preferably 0.0001 ≤ a2 ≤ 0.008, and 0.0 ≤ d2 ≤ 0.0175, preferably 0.0 ≤ d2 ≤ 0.015, more preferably 0.0 ≤ d2 ≤ 0.0125, and most preferably, d2 is approximately 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, and Si.

[0058] In certain preferred embodiments, 0.55 ≤ x2 ≤ 0.75, preferably 0.58 ≤ x2 ≤ 0.72, more preferably 0.60 ≤ x2 ≤ 0.70.

[0059] 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 an entire positive electrode active material containing one or more elements other than Li, Ni, Mn, Co, Si, and O, which are reflected in the parameter "D2" used herein. A preferred embodiment is a positive electrode active material according to the present invention containing D2, where D2 is at least one element selected from the group consisting of Al, B, Ba, Ca, Ce, Cr, Fe, La, Mg, Mo, Nb, S, Sr, Ti, V, W, Y, Zr, and Zn, preferably Al, B, Ti, Cr, Nb, S, Y, and W, more preferably Al, B, Ti, Nb, and W.

[0060] [Surface layer] The present invention relates to a positive electrode active material according to the present invention, wherein the positive electrode active material contains silicon with a content of Si B and contains silicon as Si Bis expressed as mole fraction Si relative to the sum of the mole fractions of Ni, Mn, Co, and Si, as measured by XPS analysis, and Si B is greater than 0.05.

[0061] In a preferred embodiment, the positive electrode active material is Si B is greater than 0.1, preferably Si B is more than 0.15, more preferably Si B is greater than 0.2. In a preferred embodiment, Si B is less than 5.0, preferably Si B is less than 2.0, more preferably Si B is less than 1.0. In a preferred embodiment, Si B is in the range of 0.1 to 5.0, and preferably Si B is in the range of 0.15 to 2.0, and more preferably, Si B is in the range of 0.2 to 1.0.

[0062] In certain preferred embodiments, the positive electrode active material is Si B is greater than 0.35, preferably Si B is more than 0.5, more preferably Si B is greater than 0.8. In a preferred embodiment, Si B is less than 5.0, preferably Si B is less than 2.0, more preferably Si B is less than 1.0. In a preferred embodiment, Si B is in the range of 0.35 to 5.0, and preferably Si B is in the range of 0.50 to 2.0, and more preferably, Si B is in the range of 0.80 to 1.0.

[0063] In certain preferred embodiments, the positive electrode active material is Si B is greater than 0.1, preferably Si B is more than 0.15, more preferably Si B is greater than 0.2. In certain preferred embodiments, SiB is less than 1.0, preferably Si B is less than 0.98, more preferably Si B is less than 0.9. In a preferred embodiment, Si B is in the range of 0.1 to 1.0, and preferably Si B is in the range of 0.15 to 0.98, and more preferably, Si B is in the range of 0.2 to 0.9.

[0064] In certain preferred embodiments, the positive electrode active material is Si B is greater than 0.35, preferably Si B is more than 0.5, more preferably Si B is greater than 0.8. In a preferred embodiment, Si B is less than 1.0, preferably Si B is less than 0.98, more preferably Si B is less than 0.9. In a preferred embodiment, Si B is in the range of 0.35 to 1.0, and preferably Si B is in the range of 0.50 to 0.98, and more preferably, Si B is in the range of 0.80 to 0.98.

[0065] In certain preferred embodiments, the positive electrode active material is Si B is greater than 0.1, preferably Si B is more than 0.15, more preferably Si B is greater than 0.2. In a preferred embodiment, Si B is less than 1.0, preferably Si B is less than 0.5, more preferably Si B is less than 0.4. In a preferred embodiment, Si B is in the range of 0.1 to 1.0, and preferably Si B is in the range of 0.15 to 0.5, and more preferably, Si B is in the range of 0.2 to 0.4.

[0066] In one embodiment, the positive electrode active material according to the present invention has a content of Si C and further containing silicon, Si C is expressed as mole fraction Si relative to the sum of the mole fractions of Ni, Mn, and Co, as measured by XPS analysis, and Si C is greater than 0.05.

[0067] In a preferred embodiment, the positive electrode active material is Si C is greater than 0.10, preferably Si C is more than 0.15, more preferably Si C is greater than 0.20. In a preferred embodiment, Si C is less than 50.0, preferably Si C is less than 15.0, more preferably Si C is less than 1.0. In a preferred embodiment, Si C is in the range of 0.10 to 50.0, and preferably Si C is in the range of 0.15 to 15.0, and more preferably, Si C is in the range of 0.20 to 1.0.

[0068] In certain preferred embodiments, the positive electrode active material is Si C is greater than 1.0, preferably Si C is more than 5.0, more preferably Si C is greater than 10.0. In a preferred embodiment, Si C is less than 50.0, preferably Si C is less than 40.0, more preferably Si C is less than 30.0. In a preferred embodiment, Si C is in the range of 1.0 to 50.0, and preferably Si C is in the range of 5.0 to 40.0, and more preferably, Si C is in the range of 10.0 to 30.0.

[0069] In a preferred embodiment, the positive electrode active material according to the present invention has a Si content Si defined as a' / (x'+y'+z'+a'). 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 over 5.0.

[0070] In a preferred embodiment, the positive electrode active material is, in accordance with the present invention, B / Si A is greater than 10.0, preferably the ratio Si B / Si A is more than 15.0, more preferably, the ratio Si B / Si A In a preferred embodiment, the positive electrode active material has a ratio Si B / Si A is less than 1000.0, preferably the ratio Si B / Si A is less than 500.0, more preferably, the ratio Si B / Si A In a preferred embodiment, the positive electrode active material has a ratio Si B / Si A is in the range of 10.0 to 1000.0, preferably, the ratio Si B / Si A is in the range of 15.0 to 500.0, more preferably, the ratio Si B / Si A is in the range of 20.0 to 100.0.

[0071] In certain preferred embodiments, the cathode active material is, in accordance with the present invention, B / Si A In certain preferred embodiments, the positive electrode active material has a ratio Si B / Si AIn certain preferred embodiments, the positive electrode active material has a ratio Si B / Si A is in the range of 80.0 to 120.0.

[0072] In the context of the present invention, Si B or Si C is 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 point from the second point is equal to the XPS penetration depth, and the penetration depth D' is in the range of 1.0 to 10.0 nm. In particular, the penetration depth is the distance along an axis tangent to the outer edge, passing through the first point, and perpendicular to an imaginary line.

[0073] 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 provides the atomic content of elements in the top layer of the particle, with a penetration depth of approximately 10.0 nm from the particle's outer boundary. The particle's outer boundary 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).

[0074] In the framework of the present invention, at% means atomic percentage. At% or "atomic percent" of a given elemental expression of concentration means what percentage of all atoms in said compound are atoms of said element. Furthermore, in the framework of the present invention, the designation at% is equivalent to mole% or "mole percent".

[0075] As will be appreciated by those skilled in the art, the defined ratio Si B / Si A" refers to a positive electrode active material of the present invention having a rich amount of Si in the surface layer of the positive electrode active material. The surface layer of the positive electrode active material is the topmost 1 to 10 nm of the positive electrode active material. In other words, the positive electrode active material of the present invention includes a Si surface layer. For example, although not limited to the present invention, the Si compound present in the surface layer of the positive electrode active material is Li2SiO3.

[0076] 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, Zr, and Zn, preferably Al, B, Ti, Cr, Nb, S, Y, and W, more preferably Al, B, Ti, Nb, and W, and a surface layer of Si may be disposed on the first surface layer, and / or the first surface layer may be disposed on a surface layer of Si, and / or the positive electrode active material layer may include a mixed surface layer including the surface layer of Si and the first surface layer.

[0077] A particularly preferred embodiment is a cathode active material according to the present invention, the cathode active material comprising: - Si content in the range of 0.10 to 5.0 B and preferably Si B is in the range of 0.15 to 2.0, more preferably Si B is in the range of 0.20 to 1.0, Si B and, - Si content in the range of 0.10 to 50.0 C and preferably Si C is in the range of 0.15 to 15.0, more preferably Si C is in the range of 0.20 to 1.0, Si C and a positive electrode active material having the above formula.

[0078] A particularly preferred embodiment is a positive electrode active material according to the present invention, wherein the positive electrode active material comprises: - Si content in the range of 0.35 to 5.0 B and preferably Si Bis in the range of 0.50 to 2.0, more preferably Si B is in the range of 0.80 to 1.0, Si B and, - Si content in the range of 1.0 to 50.0 C and preferably Si C is in the range of 5.0 to 40.0, more preferably Si C is in the range of 10.0 to 30.0, Si C and a positive electrode active material having the above formula.

[0079] A particularly preferred embodiment is a cathode active material according to the present invention, the cathode active material comprising: - Si content in the range of 0.10 to 5.0 B and preferably Si B is in the range of 0.15 to 2.0, more preferably Si B is in the range of 0.20 to 1.0, Si B and, - Ratio Si in the range of 10.0 to 1000.0 B / Si A and preferably, the ratio Si B / Si A is in the range of 15.0 to 500.0, more preferably, the ratio Si B / Si A The ratio Si is in the range of 20.0 to 100.0. B / Si A and a positive electrode active material having the above formula.

[0080] A particularly preferred embodiment is a positive electrode active material according to the present invention, wherein the positive electrode active material comprises: - Si content in the range of 0.35 to 5.0 B and preferably Si B is in the range of 0.50 to 2.0, more preferably Si B is in the range of 0.80 to 1.0, Si B and, - Specific Si B / Si A is in the range of 80.0 to 120.0, the ratio Si B / Si Aand a positive electrode active material having the above formula.

[0081] A particularly preferred embodiment is a cathode active material according to the present invention, the cathode active material comprising: - Si content in the range of 0.10 to 5.0 B and preferably Si B is in the range of 0.15 to 2.0, more preferably Si B is in the range of 0.20 to 1.0, Si B and, - Si content in the range of 0.10 to 50.0 C and preferably Si C is in the range of 0.15 to 15.0, more preferably Si C is in the range of 0.20 to 1.0, Si C and, - Ratio Si in the range of 10.0 to 1000.0 B / Si A and preferably, the ratio Si B / Si A is in the range of 15.0 to 500.0, more preferably, the ratio Si B / Si A is in the range of 20.0 to 100.0, the ratio Si B / Si A and a positive electrode active material having the above formula.

[0082] A particularly preferred embodiment is a positive electrode active material according to the present invention, wherein the positive electrode active material comprises: - Si content in the range of 0.35 to 5.0 B and preferably Si B is in the range of 0.50 to 2.0, more preferably Si B is in the range of 0.80 to 1.0, Si B and, - Si content in the range of 1.0 to 50.0 C and preferably Si C is in the range of 5.0 to 40.0, more preferably Si B is in the range of 10.0 to 30.0, Si C and, - Specific SiB / Si A is in the range of 80.0 to 120.0, the ratio Si B / Si A and a positive electrode active material having the above formula.

[0083] In a preferred embodiment, the particles have a Co content of Co when measured by cross-sectional EDS (CS-EDS) at the edge of the particle. edge Co edge is expressed in mole % relative to the sum of Ni, Mn, and Co contents when measured by CS-EDS at the edge of the particle, and Co contentCo when measured by CS-EDS at the center of the particle. center Co center is expressed in mole % relative to the total Ni, Mn, and Co content, and the ratio Co edge / Co center is greater than 1.10, preferably the ratio Co edge / Co center is more than 1.20, more preferably the ratio Co edge / Co center is greater than 1.30, most preferably the ratio Co edge / Co center is over 1.50.

[0084] In a preferred embodiment, the particles have an Al content Al, defined as c / (x+y+z+c). A where c is the Al content as measured by XPS, and the positive electrode active material has an Al content of Al B and Al B was determined by XPS analysis, and Al B is expressed as a mole fraction relative to the sum of the mole fractions of Co, Mn, Ni, and Al, as measured by XPS analysis, and the ratio Al B / Al A is greater than 1.0, preferably the ratio Al B / Al A is more than 2.0, more preferably, the ratio Al B / Al A is greater than 2.5, and even more preferably, the ratio Al B / Al Ais greater than 3.0, and even more preferably, the ratio Al B / Al A is greater than 3.5, most preferably the ratio Al B / Al A is over 4.0.

[0085] [form] The present invention provides a positive electrode active material according to the present invention, which includes single-crystal particles.

[0086] In the context of the present invention, a particle is considered to be single crystalline if it consists of only one particle or at most five particles, preferably at most three particles, as observed 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, where preferably the atomic planes of the two particles are aligned in different orientations and meet as a crystalline discontinuity.

[0087] 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. As will be understood by those skilled in the art in these certain preferred embodiments, all embodiments relating to single-crystal particles apply equally to the monolithic particles as defined in the present invention.

[0088] As will be appreciated by those skilled in the art, polycrystalline particles are aggregated by five or more single-crystal particles, preferably ten or more single-crystal particles, and more preferably fifty or more single-crystal particles. This can be observed with a suitable microscopic technique, such as a scanning electron microscope (SEM), by observing the grain boundaries. The aggregation of single-crystal particles into polycrystalline particles occurs under post-treatment processes, such as heat treatment processes.

[0089] Certain preferred embodiments relate to cathode active materials of the present invention comprising single-crystalline particles having a primary particle median D50 value of less than 15 μm, preferably less than 10 μm, and more preferably less than 5 μm. Certain preferred embodiments relate to cathode active materials of the present invention comprising single-crystalline 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-crystalline particles having a primary particle median D50 value of 1 to 15 μm, preferably 2 to 10 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 size, more preferably the particle size at 50% of the cumulative volume percent distribution 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.

[0090] As will be understood by those skilled in the art, the single crystal particles have a Si content of A , SiB、 Si C , and their corresponding ratios.

[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 containing single particles and / or secondary particles, and as observed in an SEM image, each single particle consists of only one primary particle, and each secondary particle consists of at least two primary particles and at most 20 primary particles.

[0092] Preferably, at least 30% of the particles constituting the powder observed in the SEM image, more preferably at least 50% of the particles, are single particles and / or secondary particles. The number of primary particles constituting a single particle and / or secondary particle 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 aggregated by 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 is composed of more than 20 primary particles, preferably 50 or more primary particles, and more preferably 100 or more primary particles, as observed in an SEM image.

[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 a further aspect, the present invention provides a single-crystalline particle-based positive electrode active material for a solid-state battery, comprising lithium, oxygen, nickel, and at least one metal selected from the group consisting of manganese and cobalt, The positive electrode active material has a Si content B Further containing silicon, Si B is expressed as mole fraction Si relative to the sum of the mole fractions of Ni, Mn, Co, and Si, as measured by XPS analysis, Si B is greater than 0.05.

[0098] 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 material C , Si B , Si A , and the various embodiments regarding the identity and amount of carbon content are equally applicable to single-crystal particle-based positive electrode active materials.

[0099] [method] In a second aspect, the present invention provides a method for producing a cathode active material, the method comprising: Step a) mixing a lithium transition metal based oxide compound with a source of silicon; Step b) heating the mixture in an oxidizing atmosphere in a furnace at a temperature of less than 500° C. for 1 hour to 20 hours to obtain the positive electrode active material.

[0100] In a highly preferred embodiment of the method for producing a cathode active material of the present invention, the cathode active material is according to the first aspect of the present invention. As will be understood by those skilled in the art, when the method for producing a cathode active material of the present invention results in a cathode material according to the first aspect of the present invention, all embodiments directed to the cathode active material according to the first aspect of the present invention apply mutatis mutandis to the method for producing a cathode active material according to the first aspect of the present invention. For example, Li, M', Si as described herein in the context of the cathode active material may be used.C , Si B , Si A The various embodiments regarding the identity and amount of carbon content are equally applicable to the method of preparing the positive electrode active material.

[0101] In a preferred embodiment of the method, a lithium transition metal-based oxide compound is provided comprising Li, M″ and oxygen, wherein M″ comprises Ni, Mn, Co and D, and 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, Zr 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 typically prepared according to a lithiation process, a process in which a mixture of a transition metal oxide precursor and a further source of lithium is heated, preferably at a temperature of 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 of the elements Ni, Mn and / or Co, preferably sulfates or nitrates, more preferably sulfates, in the presence of an alkali compound, such as 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.

[0102] In a preferred embodiment of the method, the source of Si is a Si-alkoxide, an alkylalkoxysilane, or a polysiloxane, preferably an alkylalkoxysilane, or a polysiloxane.

[0103] In a preferred embodiment of the method, 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-alkoxides having the formula: 5 is C1-8 alkyl or alkenyl optionally substituted with halide, preferably C1-C4 alkyl, more preferably C1-C2 alkyl. A highly preferred source of Si is silicon tetraethoxide.

[0104] In a highly preferred embodiment of the method, the source of Si is an alkylalkoxysilane, more preferably an R alkoxysilane with a=1, 2, or 3, b=1, 2, or 3, a+b=4 6 a (R 7 O) b Si and R 6 and R 7 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 1 and R 2 are the same alkyl groups selected from the group consisting of C1-C8 alkyl or alkenyl optionally substituted with halide, preferably C1-C4 alkyl, more preferably C1-C2 alkyl, and most preferably the source of Si is methyltrimethoxysilane.

[0105] In a highly preferred embodiment, the source of Si is a polysiloxane, preferably a polydialkylsiloxane, where the alkyl 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 polymer is not limited to a particular 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. n It has.

[0106] In a particular preferred embodiment, the lithium transition metal-based oxide compound and the silicon source are mixed by dry mixing, particularly when the Si source is a polysiloxane as defined in the present invention.As will be understood by those skilled in the art, dry mixing means that no additional solvent is added to the mixture of the lithium transition metal-based oxide compound and the silicon source.

[0107] In a particularly preferred embodiment of the method, the silicon source, particularly when the silicon source is an alkylalkoxysilane as defined herein, is preferably dissolved in a first liquid. Preferably, the first liquid is water. Preferably, the lithium transition metal oxide compound containing the silicon source added to the first liquid is further mixed with a second liquid, preferably the second liquid comprises water and an alcohol, more preferably the second liquid is a mixture of water and an alcohol. Preferably, the alcohol is methanol, ethanol, propanol, butanol, or a mixture thereof, preferably methanol or ethanol, most preferably ethanol. In a preferred embodiment, the weight ratio of alcohol to water (meaning the overall content of water present in the first liquid and the second liquid) is 10:1 to 1:10, preferably 5:1 to 1:5, more preferably 2:1 to 1:2. The inventors believe that by adding water to a silicon source, which is an alkylalkoxysilane as defined in the present invention, the alkylalkoxysilane is hydrolyzed to the corresponding polyalkylsiloxane by a polycondensation reaction, which is then coated onto the positive electrode active material of the present invention by heating step b).

[0108] In a preferred embodiment, the Si content of the silicon source is at least 0.05 wt %, preferably at least 0.1 wt %, and more preferably at least 0.15 wt %, based on the total weight of the positive electrode active material. In a preferred embodiment, the Si content of the silicon source is at most 1.0 wt %, preferably at most 0.5 wt %, and more preferably at most 0.1 wt %, based on the total weight of the positive electrode active material. In a preferred embodiment, the Si content of the silicon source is in the range of 0.05 to 1.0 wt %, preferably in the range of 0.1 to 0.5 wt %, and more preferably in the range of 0.15 to 0.1 wt %, based on the total weight of the positive electrode active material.

[0109] In a preferred embodiment of the method, the mixture is heated to a temperature of at least 25° C., preferably at least 50° C., more preferably at least 65° C. In a preferred embodiment of the method, the mixture is heated to a temperature of at most 450° C., preferably at most 400° C., more preferably at most 350° C. In a preferred embodiment of the method, the mixture is heated to a temperature of 25° C. to 450° C., preferably 50° C. to 400° C., more preferably 65° C. to 350° C.

[0110] In a preferred embodiment of the method, the mixture is heated for at least 2 hours, preferably at least 3 hours, more preferably at least 4 hours. In a preferred embodiment of the method, the mixture is heated for at most 15 hours, preferably at most 10 hours, more preferably at most 7 hours. In a preferred embodiment of the method, the mixture is heated for 2 to 15 hours, preferably 3 to 10 hours, more preferably 4 to 7 hours.

[0111] In a more preferred embodiment of the method, heating the mixture comprises: At a temperature of 25°C to 450°C, preferably 50°C to 400°C, more preferably 65°C to 350°C, The time is 2 to 15 hours, preferably 3 to 10 hours, and more preferably 4 to 7 hours.

[0112] In a preferred embodiment of the method, the heating of the mixture is in an oxidizing atmosphere, preferably comprising or consisting of oxygen, such as air.

[0113] In a more preferred embodiment, heating of the mixture occurs under an oxidizing atmosphere in a furnace.

[0114] [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, in the context of the cathode active material or the method for producing said cathode active material, the Li, M', Si as described herein may be used. C , Si A , Si B The various embodiments regarding the identity and amount of and the source of silicon are equally applicable to the positive electrode active material obtained by the method for preparing a positive electrode active material.

[0115] [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.

[0116] In a preferred embodiment, the battery is a solid state battery.

[0117] In certain preferred embodiments, the solid-state battery includes a sulfide-based electrolyte. Preferably, the electrolyte is a sulfide-based solid electrolyte, and more preferably, the electrolyte includes Li, P, and S. Typically, the sulfur-containing compound is Li6PS5X, where X is F, Cl, Br, or I, preferably Cl, or Br, and the sulfur-containing compound is thio-lithium (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 P 1.44 S 11.7 Cl 0.3 , and / or Li7P3S 11 may be suitably used. In a highly preferred embodiment, the battery is a sulfide solid state battery.

[0118] In certain preferred embodiments, the solid state battery comprises a polymer-based electrolyte, preferably a polymer-based solid electrolyte, more preferably the polymer-based solid electrolyte is a polymer containing oxyethylene units, most preferably the polymer-based solid electrolyte is polyethylene oxide. w Such polymers are commercially available in a variety of different number average molecular weights. Preferably, the polyethylene oxide has a weight average molecular weight M of less than 5,000,000 g / mol and greater than 50,000 g / mol. w , preferably a weight average molecular weight M of less than 3,000,000 g / mol and more than 100,000 g / mol w , more preferably a weight average molecular weight M of less than 2,000,000 g / mol and more than 500,000 g / mol w , more preferably a weight average molecular weight M of about 1,000,000 g / mol w In a highly preferred embodiment, the battery is a polymer solid state battery.

[0119] 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.

[0120] In a preferred embodiment, a battery according to the present invention, preferably a solid-state battery comprising a sulfide-based electrolyte as defined herein, has an efficiency of at least 85%, preferably at least 86%, more preferably at least 87%, and most preferably at least 88%. As will be understood by those skilled in the art, the efficiency of a battery is determined by the initial charge capacity (CQ1) and discharge capacity (DQ1) between 4.3 V and 2.5 V (Li / Li + ), or 3.7V~1.9V(In-Li / Li + ) at a C-rate of 0.1 C in constant current mode (CC). The reversible capacity efficiency (%) is obtained according to the following formula:

[0121]

number

[0122] Preferably, the schedule uses a 1C current rating of 160mA / g.

[0123] A preferred embodiment is a battery according to the invention, preferably having a Q of less than 70 mAh / g, preferably less than 65 mAh / g, more preferably less than 50 mAh / g, most preferably less than 45 mAh / g. total As will be appreciated by those skilled in the art, the present invention relates to a solid-state battery comprising a polymer-based electrolyte as defined herein, having Q total is defined using the following coin cell test procedure at a 1C current rating of 160 mA / g over the 4.4 to 3.0 V / Li metal window range.

[0124] Step 1) Charge in constant current mode at a C rate of 0.05 with an end condition of 4.4 V, followed by leaving it to stand for 10 minutes.

[0125] Step 2) Discharge in constant current mode at a C rate of 0.05 with an end condition of 3.0 V, followed by standing for 10 minutes. The discharge capacity of this step is DQ1.

[0126] Step 3) Charge in constant current mode with a C rate of 0.05 with an end condition of 4.4V.

[0127] Step 4) Switch to constant voltage mode and maintain 4.4V for 60 hours.

[0128] Step 5) Discharge in constant current mode at a C rate of 0.05 with an end condition of 3.0 V. The discharge capacity in this step is DQ2.

[0129] In the formula, Q total is defined as the total leakage capacitance at high voltage and temperature in step 4).

[0130] [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.

[0131] A preferred embodiment is the use of the cathode active material in a battery, preferably a solid-state battery, more preferably a sulfide solid-state battery, thereby increasing the efficiency of said battery.

[0132] A preferred embodiment is the use of a positive electrode active material in a battery, preferably a solid-state battery, more preferably a polymer solid-state battery, thereby increasing the Q of said battery. total Reduces.

[0133] 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]

[0134] The following analytical methods are used in the examples.

[0135] A) Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES) The element contents in the positive electrode active materials of the examples and comparative examples described herein below were measured by inductively coupled plasma optical emission spectroscopy (ICP-OES) using an Agilent ICP 720-OES. One gram of powder sample was dissolved in 50 mL of high-purity hydrochloric acid in an Erlenmeyer flask. The flask was covered with a watch glass and heated on a hot plate at 380 °C until the sample was completely dissolved. After cooling to room temperature, the solution and rinse water in the Erlenmeyer flask were transferred to a 250 mL volumetric flask. The volumetric flask was then filled with DI water up to the 250 mL mark and then thoroughly homogenized. An appropriate amount of the solution was pipetted and transferred to a 250 mL volumetric flask for the second dilution. The volumetric flask was then filled with an internal standard and 10% hydrochloric acid up to the 250 mL mark and then homogenized. Finally, this solution was used for ICP-OES measurement. The contents of Ni, Mn, Co, and Si were expressed as weight percent of the sum of these contents. Another suitable solvent can be used to completely dissolve the positive electrode active material powder sample.

[0136] B) Particle size PSD is measured using a Malvern Mastersizer 3000 equipped with a Hydro MV wetting and dispersing accessory after dispersing examples of the cathode active material powders described herein in an aqueous medium. Sufficient ultrasonic irradiation and agitation are applied and a suitable surfactant is introduced to improve the dispersibility of the cathode active material powder examples. D50 is defined as the particle size at 50% of the cumulative volume percent distribution.

[0137] C) Polymer cell test C1) Polymer cell preparation C1.1) Solid polymer electrolyte (SPE) preparation The solid polymer electrolyte (SPE) is prepared according to the process as follows.

[0138] Step 1) Mix polyethylene oxide (PEO, 1,000,000 g / mol, Alfa Aesar) with lithium bis(trifluoromethanesulfonyl)imide salt (LiTFSI, >98.0%, TCI) in anhydrous acetonitrile 99.8 wt% (Aldrich) using a mixer at 2,000 revolutions per minute (rpm) for 30 minutes. The mass ratio of polyethylene oxide to LiTFSI is 3.0.

[0139] Step 2) Pour the mixture from step 1) into a Teflon dish and dry at 25°C for 12 hours.

[0140] Step 3) Remove the dried SPE from the dish and punch out the dried SPE to obtain an SPE disk with a thickness of 300 μm and a diameter of 19 mm.

[0141] C1.2) Positive electrode preparation The positive electrode is prepared according to the following process:

[0142] Step 1) Prepare a polymer electrolyte mixture containing polyethylene oxide (PEO, 100,000 g / mol, Alfa Aesar) in 99.7 wt% anisole anhydrous (Sigma-Aldrich) and lithium bis(trifluoromethanesulfonyl)imide salt (LiTFSI, >98.0%, TCI) in acetonitrile in a ratio of 74:26 by weight of PEO:LiTFSI.

[0143] Step 2) To prepare a slurry mixture, the polymer electrolyte mixture prepared in step 1) is mixed with a positive electrode active material and conductor powder (Super P, Timcal) in an acetonitrile solution in a ratio of 21:75:4 by weight. Mixing is carried out by a homogenizer at 5,000 rpm for 45 minutes.

[0144] Step 3) The slurry mixture from step 2) is cast onto one side of a 20 μm thick aluminum foil with a coater gap of 100 μm.

[0145] Step 4) The slurry-cast foil is dried at 30° C. for 12 hours, and then punched to obtain a cathode electrode with a diameter of 14 mm.

[0146] C1.3) Negative electrode preparation A Li foil (16 mm diameter, 500 μm thickness) is prepared as the negative electrode.

[0147] C1.4) Polymer cell assembly The coin-shaped polymer cell is assembled in an argon-filled glove box from bottom to top in the following order: 2032 coin cell cap (can), positive electrode prepared from Section C1.2, SPE prepared from Section C1.1, gasket, negative electrode prepared from Section C1.3, spacer, wave spring, and cell cap. The coin cell is then completely sealed to prevent electrolyte leakage.

[0148] C2) Test method Each coin-shaped polymer cell is cycled at 80 °C using a Toscat-3100 computer-controlled galvanostatic cycling station (Toyo). The coin cell test procedure uses a 1 C current rating of 160 mA / g over the 4.4 to 3.0 V / Li metal window range according to the following schedule:

[0149] Step 1) Charge in constant current mode at a C rate of 0.05 with an end condition of 4.4 V, followed by leaving it to stand for 10 minutes.

[0150] Step 2) Discharge in constant current mode at a C rate of 0.05 with an end condition of 3.0 V, followed by standing for 10 minutes. The discharge capacity of this step is DQ1.

[0151] Step 3) Charge in constant current mode with a C rate of 0.05 with an end condition of 4.4V.

[0152] Step 4) Switch to constant voltage mode and maintain 4.4V for 60 hours.

[0153] Step 5) Discharge in constant current mode at a C rate of 0.05 with an end condition of 3.0 V. The discharge capacity in this step is DQ2.

[0154] Q total Q is defined as the total leakage capacitance at high voltage and temperature in step 4) according to the test method described. total A low value of indicates high stability of the positive electrode active material powder during high temperature operation.

[0155] D) Sulfide cell test D1) Sulfide cell preparation D1.1) Positive electrode preparation: 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 64.0:30.0:3.0:3.0 ratio in butyl acetate solvent 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.

[0156] D1.2) Negative electrode preparation: 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.

[0157] D1.3) Separator Preparation: For the preparation of the separator, which also functions as a solid electrolyte in the battery, the Li-PS based solid electrolyte is pelletized under a pressure of 250 MPa to obtain a pellet thickness of 100 μm.

[0158] D1.4) Cell assembly: The sulfide solid-state rechargeable battery is assembled in an Ar-filled glove box from bottom to top in the following order: 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.

[0159] D2) Test method The test method is a conventional "constant cut-off voltage" test. Each cell is cycled at 60°C using a Toscat-3100 computer-controlled galvanostatic cycling station (manufactured by Toyo).

[0160] The 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:

[0161]

number

[0162] E) Exposure test Carbon and moisture exposure tests were performed by placing 40 grams of cathode active material in a 95 x 95 mm 2 The powder is spread evenly on a plate and placed in a chamber at 30°C. The atmosphere in the chamber is controlled to have a relative humidity level of 50%. After 3 days (72 hours), the positive electrode active material powder is collected for carbon analysis as described in Methods E and F for moisture analysis.

[0163] F) 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.

[0164] G) Moisture analysis The moisture content of the positive electrode active material powder is measured using a Karl Metrohm Fischer Coulometer. One gram of the positive electrode active material powder is placed in a KF furnace at 200°C under a N2 atmosphere. The evaporated moisture is introduced into the KF reactor and analyzed by KF coulometric titration.

[0165] H)X-ray photoelectron spectroscopy (XPS) In the present invention, X-ray photoelectron spectroscopy (XPS) is used to analyze the surface of positive electrode active material powder particles. In XPS measurements, signals are obtained from the top of the sample, i.e., the first few nanometers (e.g., 1 nm to 10 nm) of the surface layer. Therefore, all elements measured by XPS are contained in the surface layer.

[0166] XPS measurements were performed on the surface of the cathode active material powder particles using a Thermo K-α+ spectrometer. Monochromated Al Kα radiation (hυ = 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.

[0167] Curve fitting was performed using CasaXPS Version 2.3.19PR1.0 with Shirley-type background processing and Scofield sensitivity coefficients. Fitting parameters are from Table 2a. The lineshape GL(30) is a Gaussian / Lorentzian function with a 70% Gaussian line and a 30% Lorentzian line. LA(α, β, m) is an asymmetric lineshape where α and β define the tail broadening of the peak and m defines the width.

[0168] [Table 1]

[0169] For the Co peaks, set constraints for each defined peak according to Table 1b.

[0170] [Table 2]

[0171] The Si surface content determined by XPS represents the atomic fraction of Si in the surface layer of a particle divided by the total content of Ni, Mn, Co, and / or Si, respectively, in said surface layer, and is calculated as follows:

[0172]

number

[0173]

number

[0174] The present invention is further illustrated in the following examples:

[0175] [Comparative Example 1] A single-crystalline positive electrode active material, labeled as CEX1, was prepared according to the following steps:

[0176] Step 1) Preparation of transition metal oxide hydroxide precursor: Metal composition Ni 0.85 Mn0.07Co 0.08 Nickel-based transition metal oxide hydroxide powder (TMH1) with was prepared by a co-precipitation process in a large-scale continuous stirred tank reactor (CSTR) with mixed nickel manganese cobalt sulfate, sodium hydroxide, and ammonia.

[0177] Step 2) Oxidation of precursor: TMH1 prepared in step 1) was heated in an oxidizing atmosphere at 400° C. for 7 hours to obtain a heated product.

[0178] Step 3) First Mixing: The heated product prepared from step 2) was mixed with LiOH in an industrial blender to obtain a first mixture having a lithium to metal (Ni, Mn, and Co) ratio of 0.96.

[0179] Step 4) First heating: The first mixture from step 3) was heated in an oxidizing atmosphere at 890° C. for 11 hours to obtain a first heating product.

[0180] Step 5) Wet bead milling: The first heating product from step 4) was bead milled in a solution containing 0.5 mol% Co relative to the total molar content of Ni, Mn, and Co in the first heating product, followed by drying and sieving processes to obtain a milled product. The bead milling solid to solution weight ratio was 6:4, and milling was carried out for 20 minutes.

[0181] Step 6) Second Mixing: The ground product obtained from step 5) was mixed with 1.5 mol % Co from Co3O4 and 7.5 mol % Li from LiOH, relative to the total molar content of Ni, Mn, and Co in the ground product, respectively, in an industrial blender to obtain a second mixture.

[0182] Step 7) Second Heating: The second mixture from step 6) was heated in an oxidizing atmosphere at 760°C for 10 hours, followed by grinding and sieving with 250 ppm alumina powder to obtain CEX1 containing Ni, Mn, and Co in a ratio of Ni:Mn:Co of 0.84:0.07:0.09 as determined by ICP-OES. CEX1 has a D50 of 4 μm.

[0183] By the wet grinding in step 5), CEX1 is a single crystal powder (i.e., a powder containing single particles and / or secondary particles, each single particle consisting of only one primary particle, and each secondary particle consisting of at least two primary particles and at most twenty primary particles).

[0184] [Example 1] EX1.1 was prepared by mixing CEX1 with 2000 ppm Si from trimethylsiloxy-terminated polydimethylsiloxane (PDMS-C) in an industrial blender, followed by heating under a flow of oxygen gas at 75° C. for 6 hours. PDMS-C is a liquid with a molecular weight of approximately 410 g / mol.

[0185] EX1.2 was prepared according to the same method as EX1.1, except that the heating temperature was 150°C.

[0186] EX1.3 was prepared according to the same method as EX1.1, except that the heating temperature was 300°C.

[0187] [Example 2] EX2.1 was prepared by mixing CEX1 with 2000 ppm Si from hydroxy-terminated polydimethylsiloxane (PDMS-O) in an industrial blender, followed by heating under a flow of oxygen gas at 75°C for 6 hours. PDMS-O is a liquid with a molecular weight of approximately 4200 g / mol.

[0188] EX2.2 was prepared according to the same method as EX2.1, except that the heating temperature was 150°C.

[0189] EX2.3 was prepared according to the same method as EX2.1, except that the heating temperature was 300°C.

[0190] Comparative Example 2 A polycrystalline positive electrode active material labeled as CEX2.1 was prepared according to the following steps.

[0191] Step 1) Mixing: In an industrial blender, TMH1 prepared from step 1) of CEX1 was mixed with LiOH to obtain a first mixture having a lithium to metal (Ni, Mn, and Co) ratio of 0.98.

[0192] Step 2) Heating: The first mixture from step 1) was heated in an oxidizing atmosphere at 785°C for 10 hours to obtain CEX2 containing Ni, Mn, and Co in a ratio of Ni:Mn:Co of 0.85:0.07:0.08 as determined by ICP-OES. CEX1 has a D50 of 4 μm.

[0193] CEX2.2 was prepared by mixing CEX2.1 with 2000 ppm Si from PDMS-C in an industrial blender, followed by heating at 75° C. under a flow of oxygen gas for 6 hours.

[0194] CEX2.3 was prepared according to the same method as CEX2.2, except that the heating temperature was 150°C.

[0195] CEX2.4 was prepared according to the same method as CEX2.2, except that the heating temperature was 300°C.

[0196] Comparative Example 3 CEX3.1 was prepared by mixing CEX2.1 with 2000 ppm Si from PDMS-O in an industrial blender, followed by heating at 75° C. for 6 hours under a flow of oxygen gas.

[0197] CEX3.2 was prepared according to the same method as EX2.1, except that the heating temperature was 150°C.

[0198] CEX3.3 was prepared according to the same method as EX2.1, except that the heating temperature was 300°C.

[0199] [Example 3] EX3.1 was prepared according to the following steps.

[0200] Step 1) Mixing: In an industrial blender, mix 300 grams of CEX1 with 2.97 grams of methyltrimethoxysilane (CH3Si(OCH3)3).

[0201] Step 2) Heating: The mixture prepared from step 1) is heated under flowing oxygen gas at 350° C. for 6 hours to produce EX3.1 with 2000 ppm Si.

[0202] EX3.2 was prepared according to the following steps:

[0203] Step 1) Preparation of methyltrimethoxysilane solution: Mix 2.97 grams of methyltrimethoxysilane with 0.8 grams of water.

[0204] Step 2) Mixing: 300 grams of CEX1, 9.7 grams of water, and the methyltrimethoxysilane solution prepared from step 1) are mixed in an industrial blender.

[0205] Step 3) Heating: The mixture prepared from step 2) is heated under flowing oxygen gas at 350° C. for 6 hours to produce EX3.2 containing about 2000 ppm Si.

[0206] EX3.3 was prepared following the same method as EX3.2, except that 8.25 grams of ethanol was used instead of water in step 2).

[0207] EX3.4 was prepared according to the same method as in Example 3.2, except that in step 1), 0.30 grams of methyltrimethoxysilane was mixed with 0.05 grams of water, and in step 2), 11.1 grams of ethanol was used instead of water. EX3.4 contains approximately 200 ppm Si.

[0208] EX3.5 was prepared according to the same method as EX3.3, except that in step 1), 0.74 grams of methyltrimethoxysilane was mixed with 0.20 grams of water, and in step 2), 10.6 grams of ethanol was used instead of water. EX3.5 contains approximately 500 ppm Si.

[0209] EX3.6 was prepared according to the same method as EX3.3, except that in step 1), 1.48 grams of methyltrimethoxysilane was mixed with 0.39 grams of water, and in step 2), 9.8 grams of ethanol was used instead of water. EX3.6 contains approximately 1000 ppm Si.

[0210] [result]

[0211] [Table 3]

[0212] [Table 4]

[0213] Tables 2 and 3 summarize the process and properties of the examples and comparative examples, with variations in morphology, Si source, Si amount, and heating temperature. XPS analysis revealed that Si B or Si C A value higher than 0 indicates that Si is present on the surface of the positive electrode active material, as is relevant for XPS measurements, where the signal is obtained from the top of the sample, i.e., the first few nanometers (e.g., 1 nm to 10 nm) of the surface layer.

[0214] From Table 2, it can be observed that the cathode active material has a combination of single crystal morphology (i.e., has single particles and / or secondary particles), where each single particle consists of only one primary particle, each of the secondary particles consists of at least two primary particles and at most 20 primary particles, and where the Si on the surface has a capacity (Q total ) leakage can be better suppressed. Furthermore, for the cathode active material containing single-crystal morphology and Si on the surface, a low carbon level is observed after the 3-day exposure test.

[0215] In Table 3, all forms of the cathode active material are single crystalline and methyltrimethoxysilane is used as the source of Si. Further benefits are observed in reduced moisture levels after a 3-day exposure test and improved efficiency in sulfide cells.

Claims

1. A cathode active material for a solid-state battery, comprising lithium, oxygen, nickel, and at least one metal selected from the group consisting of manganese and cobalt, The positive electrode active material has a content of Si Ｂ and further containing silicon, Si Ｂ is expressed as mole fraction Si relative to the sum of the mole fractions of Ni, Mn, Co, and Si, as measured by XPS analysis, Si Ｂ is greater than 0.05, The positive electrode active material includes single crystal particles.

2. 2. The cathode active material of claim 1, further having a carbon content in the range of 150 ppm to 2000 ppm, preferably in the range of 250 ppm to 1850 ppm, more preferably in the range of 300 ppm to 1700 ppm, by total weight of the cathode active material, as measured by a carbon analyzer.

3. Si Ｂ is in the range of 0.1 to 1.0, and preferably Si Ｂ is in the range of 0.15 to 0.98, and more preferably, Si Ｂ The positive electrode active material according to claim 1 or 2, wherein is in the range of 0.2 to 0.

9.

4. The positive electrode active material has a content of Si Ｃ and further containing silicon, Si Ｃ is expressed as mole fraction Si relative to the sum of the mole fractions of Ni, Mn, and Co, as measured by XPS analysis, and Si Ｃ is in the range of 0.10 to 50.0, and preferably Si Ｃ is in the range of 0.15 to 15.0, and more preferably, Si Ｃ The positive electrode active material according to any one of claims 1 to 3, wherein is in the range of 0.20 to 1.

0.

5. comprising Li, Ni, Mn, Co, and oxygen; - Ni with a content x, with 50.0≦x≦98.0 mol %, relative to the sum of Ni, Mn and Co, a Mn content y, with 0.0≦y≦30.0 mol %, relative to the sum of Ni, Mn, and Co; a content z of Co, with 0.0≦z≦30.0 mol %, relative to the sum of Ni, Mn and Co, The positive electrode active material according to any one of claims 1 to 4, wherein x, y, and z are measured by ICP-OES.

6. Li, M', and oxygen, wherein M' is Ni with a content x′, with 50.0≦x′≦98.0 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′, where 0.0≦z′≦30.0 mol % relative to M′, and - a content a' of Si, with 0.0<a'≦5.0 mol % relative to M', and D with a content d', where D is an element other than Li, Ni, Mn, Co, Si and oxygen, and 0.0≦d'≦2.0 mol % relative to M', where x', y', z', a' and d' are measured by ICP-OES; The positive electrode active material according to claim 5 , wherein x′+y′+z′+a′ is 100.0 mol %.

7. The positive electrode active material has a Si content Si defined as a' / (x'+y'+z'+a'). Ａ and has a ratio Si Ｂ / Si Ａが、 The positive electrode active material according to claim 6 , wherein the σ is greater than 5.

0.

8. The ratio Si Ｂ / Si Ａ is greater than 10.0, preferably the ratio Si Ｂ / Si Ａ is more than 15.0, more preferably, the ratio Si Ｂ / Si Ａ The positive electrode active material according to claim 7 , wherein the σ is greater than 20.

0.

9. 9. The positive electrode active material according to claim 6, wherein x' is 55.0 mol%≦x'≦90.0 mol%, preferably 58.0 mol%≦x'≦88.0 mol%, more preferably 60.0 mol%≦x'≦85.0 mol%, relative to M'.

10. 10. The cathode active material of claim 1, having a carbon uptake of less than 1500 ppm by total weight of the cathode active material, preferably less than 1200 ppm by total weight of the cathode active material, more preferably less than 1000 ppm by total weight of the cathode active material, wherein the carbon uptake is measured by exposure testing.

11. A method for producing a cathode active material, preferably the cathode active material according to any one of claims 1 to 10, said method comprising: Step a) mixing a lithium transition metal based oxide compound with a source of silicon; Step b) heating the mixture in an oxidizing atmosphere in a furnace at a temperature less than 500° C. for 1 hour to 20 hours to obtain the positive electrode active material.

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

13. A solid-state battery comprising the positive electrode active material according to any one of claims 1 to 10.

14. 14. The solid-state battery of claim 13, comprising a polymer-based solid electrolyte or a sulfide-based solid electrolyte.

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.

Images