Positive electrode active material powder

Abstract

The present disclosure relates to a positive electrode active material powder for lithium (Li) ion rechargeable batteries. The present disclosure further relates to a method of preparing said positive electrode active material powder, a battery comprising said positive electrode active material powder, and to the use of the battery.

Description

DESCRIPTIONTITLEPOSITIVE ELECTRODE ACTIVE MATERIAL POWDERTECHNICAL FIELD

[0001] The present disclosure relates to a positive electrode active material powder for lithium (Li) ion rechargeable batteries. The present disclosure further relates to a method of preparing said positive electrode active material powder, a battery comprising said positive electrode active material powder, and to the use of the battery.BACKGROUND

[0002] The demand for Li-ion rechargeable batteries has been consistently high in recent years due to their widespread use in various applications such as consumer electronics, electric vehicles, energy storage systems, and more. Much research is concentrated on developing Li-ion rechargeable batteries with enhanced electrochemical performance, such as the reduction of the retention capacity loss and the mitigation of the resistance increase over many cycles.

[0003] During the charging and / or discharging of Li-ion rechargeable batteries, the increased contact area between electrolyte and positive electrode active material powder may result in additional side reactions and even increase of the charge transfer resistance. Furthermore, polycrystalline particles may suffer from cracking along their grain boundaries under stringent operation conditions, which may lead to side reactions during electrochemical cycling. In order to overcome these shortcomings, monolithic particles, which are hereby defined as particles consisting of at least one primary particle and at most twenty primary particles, are utilized. Monolithic particles can maintain their morphological integrity in the absence of anisotropic forces even if operated under extreme conditions, and reduce gas evolution during electrochemical cycling.

[0004] Monolithic particles may be obtained by milling polycrystalline particles comprising a plurality of primary particles. WO2023 / 118257A1 discloses a method of obtaining single-crystalline particles by milling a lithiated transition metal oxide with a solution containing cobalt to enhance the electrochemical properties. However, there is still room for improvement.

[0005] Accordingly, there is a need for a positive electrode active material powder comprising monolithic particles that may further enhance the electrochemical performance of Li-ion rechargeable batteries.SUMMARY OF THE DISCLOSURE

[0006] The present disclosure provides a positive electrode active material powder for Li-ion rechargeable batteries, wherein the positive electrode active material powder comprises monolithic particles comprising Li, Ml, and oxygen (0), wherein Ml consists of:Nickel (Ni) in an atomic content xl, wherein about 70.0 at% < xl < 100.0 at%, relative to a total amount of Ml;Manganese (Mn) in an atomic content yl, wherein 0.0 at% < yl < about 10.0 at%, relative to a total amount of Ml;Cobalt (Co) in an atomic content zl, wherein 0.0 at% < zl < about 10.0 at%, relative to a total amount of Ml;Magnesium (Mg) in an atomic content al, wherein 0.0 at% < al < about 3.0 at%, relative to a total amount of Ml; andDI in an atomic content dl, wherein 0.0 at% < dl < about 7.0 at%, relative to a total amount of Ml, wherein Dl is at least one element other than Li, Ni, Mn, Co, Mg, and O, wherein xl+yl+zl+al-i-dl is 100.0 at%, wherein xl, yl, zl, al, and dl are determined by Inductively Coupled Plasma - Optical Emission Spectroscopy (ICP- OES), and wherein the positive electrode active material powder is obtainable by a method comprising: a. providing a mixed-metal oxide comprising Li, M2, and O, wherein M2 consists of:Ni in an atomic content x2, wherein about 70.0 at% < x2 < 100.0 at%, relative to a total amount of M2;Mn in an atomic content y2, wherein 0.0 at% < y2 < about 10.0 at%, relative to a total amount of M2;Co in an atomic content z2, wherein 0.0 at% < z2 < about 10.0 at%, relative to a total amount of M2;D2 in an atomic content d2, wherein 0.00 at% < d2 < about 10.0 at%, relative to a total amount of M2, wherein D2 is at least one element other than Li, Ni, Mn, Co, and O,wherein x2+y2+z2+a2+d2 is 100.0 at%, and wherein x2, y2, z2, a2, and d2 are determined by ICP-OES; b. milling the mixed-metal oxide with a solution comprising a Mg-containing compound to obtain a milled material; c. mixing the milled material with a first Co-containing compound to obtain a mixture; and d. heating the mixture to obtain the positive electrode active material powder.

[0007] The present inventors have found that the electrochemical performance of Li-ion rechargeable batteries may be enhanced by employing the positive electrode active material powder according to the present disclosure. Specifically, the retention capacity loss may be decreased, and the direct current resistance (DCR) growth may be decreased over the repeated cycles of charging and discharging. Without wishing to be bound by any theory, the positive electrode active material powder according to the present disclosure, obtainable by the method of milling the mixed-metal oxide with the solution comprising the Mg-containing compound, may comprise monolithic particles with homogeneously distributed Mg on their surface, leading to the enhanced electrochemical performance.

[0008] The present disclosure provides a battery, in particular a Li ion rechargeable battery, comprising said positive electrode active material powder according to any embodiment or combination of embodiments of the present disclosure.

[0009] The present disclosure also provides the use of said battery in rechargeable batteries across a wide range of electrically powered devices and systems. Electrically powered devices and systems comprising the battery include consumer electronics such as portable computers, tablets, mobile phones, and telecommunication devices. Industrial applications encompass power tools, mobile machinery, and robotic devices. In the domain of energy infrastructure, the battery may be employed in energy storage systems and uninterruptible power supply (UPS) systems.BRIEF DESCRIPTIONS OF THE FIGURES

[0010] Figure 1 is a graph based on the data of Table 1, showing the DCR. growth at 45°C according to the cycle number from the 1stcycle to the 700thcycle for EXI, CEX1-1 to CEX1-3, and CEX1-4.

[0011] Figure 2 is a graph based on the data of Table 1, showing the DCR growth at 45°C according to the cycle number from the 1stcycle to the 700thcycle for EX2, CEX2-1 to CEX2-4, and CEX2-5.

[0012] Figure 3 is a graph based on the data of Table 1, showing the DCR. growth at 45°C according to the cycle number from the 1stcycle to the 700thcycle for EX2, CEX3-1, CEX3-2, and CEX3-3.

[0013] Figure 4 is a graph based on the data of Table 2, showing the retention capacity at 45°C according to the cycle number from the 1stcycle to the 700thcycle for EXI, CEX1-1 to CEX1-3, and CEX1-4.

[0014] Figure 5 is a graph based on the data of Table 2, showing the retention capacity at 45°C according to the cycle number from the 1stcycle to the 700thcycle for EX2, CEX2-1 to CEX2-4, and CEX2-5.

[0015] Figure 6 is a graph based on the data of Table 2, showing the retention capacity at 45°C according to the cycle number from the 1stcycle to the 700thcycle for EX2, CEX3-1, CEX3-2, and CEX3-3.

[0016] Figure 7 is an image of CEX1-2, taken with Field Emission-Scanning Electron Microscope Energy-Dispersive X-ray Spectroscopy (FE-SEM EDX) at a magnification of 5,000.

[0017] Figure 8 is an image of EXI, taken with FE-SEM EDX at a magnification of 5,000.DETAILED DESCRIPTION OF THE DISCLOSURE

[0018] In the following detailed description, preferred embodiments are described in detail to enable practice of the present disclosure. Although the present disclosure is described with reference to these specific preferred embodiments, it will be understood that the present disclosure is not limited to these preferred embodiments. To the contrary, the present disclosure includes numerous alternatives, modifications and equivalents as will become apparent from consideration of the following detailed description. Unless otherwise indicated, it is not meant that the alternatives, modifications, and equivalents described herein are understood as separate, non-combinable, embodiments. That is, provided it is technically feasible, the different parts of the present disclosure may be combined with one another.

[0019] "at%" signifies atomic percentage. The at% or "atomic percent" of a given element means a percentage of atoms of said element among all atoms in a claimed composition. ICP-OES provides weight percent (wt%) of each element included in a material whose composition is determined by this technique. Conversion from wt% to at%, as is well known to a person skilled in the art, is as follows: at% of a first element Ei Eati) in a material can be converted from a given wt% of said first element Ei EVM ) in said material by applying the following formula,wherein Eawiis a standard atomic weight of the first element Ei, Ewtiis wt% of an ithelement , EaWiis a standard atomic weight of said ithelement , and n is an integer which represents the number of types of all elements included in the material.

[0020] "About" as used herein referring to a measurable value such as a parameter, an amount, a temporal duration, and the like, is meant to encompass variations of + / -20% or less, preferably + / -10% or less, more preferably + / -5% or less, even more preferably + / -1% or less, and still more preferably + / -0.1% or less of and from the specified value, in so far such variations are appropriate to perform in the present disclosure. However, it is to be understood that the value to which the modifier "about" refers is itself also specifically disclosed.

[0021] "Monolithic" particles refer to particles, wherein each of the particles consists of at least one primary particle and at most twenty primary particles. The number of primary particles constituting the monolithic particle may be determined by counting the primary particles observed in a Scanning Electron Microscope (SEM) image at a magnification of 2,000 from a top view, where the whole shape of the monolithic particle is taken. In the context of the present disclosure, primary particles may be distinguished from each other in a SEM image by observing grain boundaries between the primary particles. A grain boundary is defined as the interface between two primary particles, preferably wherein the atomic planes of the two primary particles are aligned to different orientations and meet as a crystalline discontinuity.

[0022] As used herein, a range of values "from X to Y," "between X and Y," and "for X to Y" include the endpoints of X and Y.

[0023] "Milling" as used herein is the action of reducing the size of particles by a mechanical action submitting the particles to a stress. Some cracks will appear under the stress, and subsequently the particle will be broken in different parts.

[0024] "Homogeneous distribution" on the surface of particles as used herein is determined by analyzing an image taken with Field Emission-Scanning Electron Microscope Energy Dispersive X-ray Spectroscopy (FE-SEM EDX) at a magnification of 5,000, wherein the image showed no metal agglomeration.Positive Electrode Active Material Powder

[0025] In a first aspect the present disclosure relates to a positive electrode active material powder for Li-ion rechargeable batteries, wherein the positive electrode active material powder comprises monolithic particles comprising Li, Ml, and oxygen (0), wherein Ml consists of:Nickel (Ni) in an atomic content xl, wherein about 70.0 at% < xl < 100.0 at%, relative to a total amount of Ml;Manganese (Mn) in an atomic content yl, wherein 0.0 at% < yl < about 10.0 at%, relative to a total amount of Ml;Cobalt (Co) in an atomic content zl, wherein 0.0 at% < zl < about 10.0 at%, relative to a total amount of Ml;Magnesium (Mg) in an atomic content al, wherein 0.0 at% < al < about 3.0 at%, relative to a total amount of Ml; andDI in an atomic content dl, wherein 0.0 at% < dl < about 7.0 at%, relative to a total amount of Ml, wherein Dl is at least one element other than Li, Ni, Mn, Co, Mg, and O, wherein xl+yl+zl+aH-dl is 100.0 at%, wherein xl, yl, zl, al, and dl are determined by Inductively Coupled Plasma - Optical Emission Spectroscopy (ICP- OES), and wherein the positive electrode active material powder is obtainable by a method comprising: a. providing a mixed-metal oxide comprising Li, M2, and O, wherein M2 consists of:Ni in an atomic content x2, wherein about 70.0 at% < x2 < 100.0 at%, relative to a total amount of M2;Mn in an atomic content y2, wherein 0.0 at% < y2 < about 10.0 at%, relative to a total amount of M2;Co in an atomic content z2, wherein 0.0 at% < z2 < about 10.0 at%, relative to a total amount of M2;D2 in an atomic content d2, wherein 0.00 at% < d2 < about 10.0 at%, relative to a total amount of M2,wherein D2 is at least one element other than Li, Ni, Mn, Co, and 0, wherein x2+y2+z2+a2+d2 is 100.0 at%, and wherein x2, y2, z2, a2, and d2 are determined by ICP-OES; b. milling the mixed-metal oxide with a solution comprising a Mg-containing compound to obtain a milled material; c. mixing the milled material with a first Co-containing compound to obtain a mixture; and d. heating the mixture to obtain the positive electrode active material powder.

[0026] In a preferred embodiment, DI is at least one selected from the group consisting of Al, zirconium (Zr), Ti, tungsten (W), strontium (Sr), boron (B), barium (Ba), calcium (Ca), chromium (Cr), fluorine (F), iron (Fe), antimony (Sb), silicon (Si), yttrium (Y), vanadium (V), zinc (Zn), and sulfur (S), preferably at least one of Al, Zr, and Ti.

[0027] In a preferred embodiment, xl may be about 75.0 at% or more, preferably about 80.0 at% or more, more preferably about 85.0 at% or more, still more preferably about 87.0 at% or more, relative to a total amount of Ml, and xl may be about 99.0 at% or less, preferably about 98.0 at% or less, more preferably about 97.0 at% or less, still more preferably about 96.0 at% or less, relative to a total amount of Ml. Specifically, the range of xl may be: about 75.0 at% < xl < about 99.0 at%, preferably about 80.0 at% < xl < about 98.0 at%, more preferably about 85.0 at% < xl < about 97.0 at%, still more preferably about 87.0 at% < xl < about 96.0 at%, relative to a total amount of Ml. Without wishing to be bound by any theory, if xl is less than about 70.0 at%, relative to a total amount of Ml, the capacity and the energy density may not be sufficient.

[0028] In a preferred embodiment, yl may be about 0.5 at% or more, preferably about 0.8 at% or more, more preferably about 1.0 at% or more, still more preferably about 1.5 at% or more, relative to a total amount of Ml, and yl may be about 9.0 at% or less, preferably about 8.0 at% or less, more preferably about 7.0 at% or less, still more preferably about 6.0 at% or less, relative to a total amount of Ml. Specifically, the range of yl may be: about 0.5 at% < yl < about 9.0 at%, preferably about 0.8 at% < yl < about 8.0 at%, more preferably about 1.0 at% < yl < about 7.0 at%, still more preferably about 1.5 at% < yl < about 6.0 at%, relative to a total amount of Ml. Without wishing to be bound by any theory, if yl ismore than about 10.0 at%, relative to a total amount of Ml, the Li-ion rechargeable batteries may suffer from structural instability resulting in poor cycling stability.

[0029] In a preferred embodiment, zl may be about 0.5 at% or more, preferably about 0.8 at% or more, more preferably about 1.0 at% or more, still more preferably about 1.5 at% or more, relative to a total amount of Ml, and zl may be about 9.0 at% or less, preferably about 8.0 at% or less, more preferably about 7.0 at% or less, still more preferably about 6.0 at% or less, relative to a total amount of Ml. Specifically, the range of zl may be: about 0.5 at% < zl < about 9.0 at%, preferably about 0.8 at% < zl < about 8.0 at%, more preferably about 1.0 at% < zl < about 7.0 at%, still more preferably about 1.5 at% < zl < about 6.0 at%, relative to a total amount of Ml. Without wishing to be bound by any theory, if zl is more than about 10.0 at%, relative to a total amount of Ml, side reactions between the blended positive electrode active material powder and the electrolyte solution may be promoted to deteriorate the electrochemical performance of the Li-ion rechargeable batteries.

[0030] In a preferred embodiment, al may be about 0.01 at% or more, preferably about 0.03 at% or more, more preferably about 0.05 at% or more, still more preferably about 0.07 at% or more, relative to a total amount of Ml, and al may be about 2.0 at% or less, preferably about 1.5 at% or less, more preferably about 1.0 at% or less, still more preferably about 0.5 at% or less, relative to a total amount of Ml. Specifically, the range of al may be: about 0.01 at% < al < about 2.0 at%, preferably about 0.03 at% < al < about 1.5 at%, more preferably about 0.05 at% < al < about 0.4 at%, still more preferably about 0.07 at% < al < about 0.2 at%, relative to a total amount of Ml. Without wishing to be bound by any theory, if al is more than about 3.0 at%, relative to a total amount of M2, the electrochemical reactions necessary for the Li ion rechargeable batteries may be hindered, leading to decreased performance.

[0031] In a preferred embodiment, dl may be about 0.05 at% or more, preferably about 0.1 at% or more, more preferably about 0.2 at% or more, still more preferably about 0.25 at% or more, relative to a total amount of Ml, and dl may be about 6.0 at% or less, preferably about 5.5 at% or less, more preferably about 5.0 at% or less, still more preferably about 4.5 at% or less, relative to a total amount of Ml. Specifically, the range of dl may be: about 0.05 at% < dl < about 6.0 at%, preferably about 0.1 at% < dl < about 5.5 at%, more preferably about 0.2 at% <dl < about 5.0 at%, still more preferably about 0.25 at% < dl < about 4.5 at%, relative to a total amount of Ml.

[0032] In a preferred embodiment, x2 may be about 75.0 at% or more, preferably about 80.0 at% or more, more preferably about 85.0 at% or more, still more preferably about 87.0 at% or more, relative to a total amount of M2, and x2 may be about 99.0 at% or less, preferably about 98.0 at% or less, more preferably about 97.0 at% or less, still more preferably about 96.0 at% or less, relative to a total amount of M2. Specifically, the range of x2 may be: about 75.0 at% < x2 < about 99.0 at%, preferably about 80.0 at% < x2 < about 98.0 at%, more preferably about 85.0 at% < x2 < about 97.0 at%, still more preferably about 87.0 at% < x2 < about 96.0 at%, relative to a total amount of M2. Without wishing to be bound by any theory, if x2 is less than about 70.0 at%, relative to a total amount of M2, the capacity and the energy density may not be sufficient.

[0033] In a preferred embodiment, y2 may be about 0.5 at% or more, preferably about 0.8 at% or more, more preferably about 1.0 at% or more, still more preferably about 1.5 at% or more, relative to a total amount of M2, and y2 may be about 9.0 at% or less, preferably about 8.0 at% or less, more preferably about 7.0 at% or less, still more preferably about 6.0 at% or less, relative to a total amount of M2. Specifically, the range of y2 may be: about 0.5 at% < y2 < about 9.0 at%, preferably about 0.8 at% < y2 < about 8.0 at%, more preferably about 1.0 at% < y2 < about 7.0 at%, still more preferably about 1.5 at% < y2 < about 6.0 at%, relative to a total amount of M2. Without wishing to be bound by any theory, if y2 is more than about 10.0 at%, relative to a total amount of M2, the Li-ion rechargeable batteries may suffer from structural instability resulting in poor cycling stability.

[0034] In a preferred embodiment, z2 may be about 0.5 at% or more, preferably about 0.8 at% or more, more preferably about 1.0 at% or more, still more preferably about 1.5 at% or more, relative to a total amount of M2, and z2 may be about 9.0 at% or less, preferably about 8.0 at% or less, more preferably about 7.0 at% or less, still more preferably about 6.0 at% or less, relative to a total amount of M2. Specifically, the range of z2 may be: about 0.5 at% < z2 < about 9.0 at%, preferably about 0.8 at% < z2 < about 8.0 at%, more preferably about 1.0 at% < z2 < about 7.0 at%, still more preferably about 1.5 at% < z2 < about 6.0 at%, relative to a total amount of M2. Without wishing to be bound by any theory, if z2 is more than about 10.0 at%, relative to a total amount of M2, side reactions betweenthe blended positive electrode active material powder and the electrolyte solution may be promoted to deteriorate the electrochemical performance of the Li-ion rechargeable batteries.

[0035] In a preferred embodiment, d2 may be about 0.05 at% or more, preferably about 0.1 at% or more, more preferably about 0.2 at% or more, still more preferably about 0.25 at% or more, relative to a total amount of M2, and d2 may be about 6.0 at% or less, preferably about 5.5 at% or less, more preferably about 5.0 at% or less, still more preferably about 4.5 at% or less, relative to a total amount of M2. Specifically, the range of d2 may be: about 0.05 at% < d2 < about 6.0 at%, preferably about 0.1 at% < d2 < about 5.5 at%, more preferably about 0.2 at% < d2 < about 5.0 at%, still more preferably about 0.25 at% < d2 < about 4.5 at%, relative to a total amount of M2.

[0036] In a preferred embodiment, D2 may be at least one selected from the group consisting of Al, Zr, Ti, W, Sr, B, Ba, Ca, Cr, F, Fe, Sb, Si, Y, V, Zn, and S, preferably at least one of Al and Zr.Method of Preparing Positive Electrode Active Material Powder

[0037] In a second aspect, the present disclosure further provides a method of preparing a positive electrode active material powder, preferably the positive electrode active material powder according to the present disclosure, comprising:1) mixing a Li source and a transition metal composite precursor to obtain a preliminary mixture;2) heating the preliminary mixture to obtain a mixed-metal oxide;3) milling the mixed-metal oxide with a solution comprising a Mg- containing compound to obtain a milled material;4) mixing the milled material with a first Co-containing compound to obtain a mixture; and5) heating the mixture to obtain the positive electrode active material powder.

[0038] Any suitable transition metal composite precursor may be used herein. For example, the transition metal composite precursor may be (oxy)hydroxide or oxide comprising Ni. The transition metal composite precursor may comprise optionally Mn, optionally Co, and optionally combinations thereof. In the transition metal composite precursor, the content of Ni relative to the total amount of thetransition metals in the precursor may be 70 at% or more, preferably 75 at% or more, more preferably 80 at% or more, still more preferably 85 at% or more.

[0039] In a preferred embodiment, the preliminary mixture comprises Li, M3, and 0, wherein M3 consist of, Ni in an atomic content x3, wherein about 70.0 at% < x3 < 100.0 at%, relative to a total amount of M3, Mn in an atomic content y3, wherein 0.0 at% < y3 < about 10.0 at%, relative to a total amount of M3, Co in an atomic content z3, wherein 0.0 at% < z3 < about 10.0 at%, relative to a total amount of M3, D3 in an atomic content d3, wherein 0.00 at% < d3 < about 10.0 at%, relative to a total amount of M3, wherein D3 is at least one element other than Li, Ni, Mn, Co, and O, wherein x3+y3+z3+a3+d3 is 100.0 at%, and wherein x3, y3, z3, a3, and d3 are determined by ICP-OES.

[0040] In a preferred embodiment, the Li source may be lithium hydroxide (LiOH), lithium hydroxide monohydrate (LiOH-HzO) and / or lithium carbonate (U2CO3), and preferably LiOH. Without wishing to be bound by any theory, it is believed that LiOH allows rapid and complete synthesis of the positive electrode active material powder at lower temperature, and can result in a good battery life cycle and safety profile because high temperature can damage the crystal structure of the positive electrode active material powder and change the oxidation state of Ni, leading to a poor performance of the battery.

[0041] In a preferred embodiment, the step of heating the preliminary mixture is performed at a temperature between 600 °C and 1000 °C, preferably between 700 °C and 950 °C, for about 5 to about 25 hours, preferably for about 7 to about 20 hours, more preferably about 9 to about 18 hours, still more preferably about 10 to about 15 hours.

[0042] In a preferred embodiment, the step of milling the mixed-metal oxide may be performed by using a bead mill. A bead mill may operate by using small, spherical grinding media (beads) that are agitated at high speeds to break down the material into finer particles. The beads may be at least one selected from the group consisting of zirconium oxide (ZrC ), alumina (AI2O3) and tungsten carbide (WC) beads. The beads may have a diameter between about 0.5 mm and about 20.0 mm, preferably about 5.0 mm and about 15.0 mm, more preferably between about 8.0 mm to about 12.0 mm. A typical milling by a bead mill may be performed by rotating a vessel filled with beads as well as a mixture of a product and a solution such that the beads should impact and / or apply a shear stress to the product. The rotationspeed may range from about 100 rpm to about 10,000 rpm, and the bead milling may continue for about 5 to about 24 hours. The apparatus of a bead mill may be equipped with an agitator, which moves to make the beads impact or friction the particles to be milled.

[0043] The positive electrode active material powder according to the present disclosure, obtainable by the method of milling the mixed-metal oxide with the solution comprising the Mg-containing compound, may comprise monolithic particles with homogeneously distributed Mg on their surface, compared to a positive electrode active material powder prepared by adding a Mg-containing compound only during the step of heating the mixture. The comparison may be confirmed by an image taken with FE-SEM EDX at a magnification of 5,000. Without wishing to be bound by any theory, the homogeneous distribution of Mg may lead to the enhanced electrochemical performance due to more uniform ion conductivity and improved charge transfer efficiency. Specifically, the positive electrode active material powder according to the present disclosure may exhibit the reduction of the retention capacity loss and DCR. growth over the repeated cycles of a Li ion rechargeable batteries.

[0044] In a preferred embodiment, the Mg-containing compound may be at least one selected from the group consisting of magnesium sulfate heptahydrate (MgSO4-7H2O), magnesium sulfate (MgSO4), magnesium acetate (Mg(CH3COO)2), magnesium nitrate (Mg(NO3)2), magnesium oxide (MgO), and magnesium chloride (MgCI2), preferably MgSO4-7H2O.

[0045] In a preferred embodiment, the content of Mg in the Mg-containing compound may be about 0.01 at% or more, preferably about 0.03 at% or more, more preferably about 0.05 at% or more, still more preferably about 0.07 at% or more, relative to a total amount of M2. The content of Mg in the Mg-containing compound may be about 2.0 at% or less, preferably about 1.5 at% or less, more preferably about 1.0 at% or less, still more preferably about 0.5 at% or less, relative to a total amount of M2. Specifically, Mg in the Mg-containing compound may be in a content from about 0.01 at% to about 2.0 at%, preferably from about 0.03 at% to about 1.5 at%, more preferably from about 0.05 at% to about 1.0 at%, still more preferably from about 0.07 at% to about 0.5 at%, relative to a total amount of M2. Without wishing to be bound by any theory, if the content of Mg in the Mg-containing compound is less than about 0.01 at%, relative to a total amount of M2, the decreaseof the retention capacity loss and DCR growth may not be sufficient, and if the content of Mg in the Mg-containing compound is more than about 2.0 at%, relative to a total amount of M2, the electrochemical reactions necessary for the Li ion rechargeable batteries may be hindered, leading to decreased performance.

[0046] In a preferred embodiment, the solution added during the step of milling the starting material may further comprise a second Co-containing compound. Without wishing to be bound by any theory, the cell thickness increase may be reduced by adding the second Co-containing compound to the solution. The second Co-containing compound may be preferably at least one selected from the group consisting of CoSO4, CoOOH, CO3O4, Co(OOC(CH3))2, Co(OH)2, CoCNCh , COCO3, C0CI2, and C0I2. The second Co-containing compound may be preferably COSO4.

[0047] In a preferred embodiment, the content of the second Co-containing compound may be about 0.01 at% or more, preferably about 0.03 at% or more, more preferably about 0.05 at% or more, still more preferably about 0.07 at% or more, relative to a total amount of M2. The content of the second Co-containing compound may be about 2.0 at% or less, preferably about 1.7 at% or less, more preferably about 1.5 at% or less, still more preferably about 1.0 at% or less, relative to a total amount of M2. Specifically, the second Co-containing compound may be in a content from about 0.01 at% to about 2.0 at%, preferably from about 0.03 at% to about 1.7 at%, more preferably from about 0.05 at% to about 1.5 at%, still more preferably from about 0.07 at% to about 1.0 at%, relative to a total amount of M2.

[0048] In a preferred embodiment, the solution added during the step of milling the starting material may further comprise an aluminum (Al)-containing compound and / or a titanium (Ti)-containing compound. Without wishing to be bound by any theory, the retention capacity loss and the DCR. growth over the repeated cycles may be reduced by adding the Al-containing compound and / or the Ti-containing compound to the solution.

[0049] In a preferred embodiment, the Al-containing compound may be at least one selected from the group consisting of aluminum sulfate hexadecahydrate (Al2(SO4)3- 16H2O), aluminum sulfate (AI2(SO4)3), aluminum oxide (AI2O3), aluminum hydroxide (AI(OH)3) and aluminum nitrate (AICNC h). The Al-containing compound may be preferably Al2(SO4)3- 16H2O.

[0050] In a preferred embodiment, the content of the Al-containing compound may be about 0.01 at% or more, preferably about 0.03 at% or more, more preferably about 0.05 at% or more, still more preferably about 0.07 at% or more, relative to a total amount of M2. The content of the Al-containing compound may be about 2.0 at% or less, preferably about 1.7 at% or less, more preferably about 1.5 at% or less, still more preferably about 1.0 at% or less, relative to a total amount of M2. Specifically, the Al-containing compound may be in a content from about 0.01 at% to about 2.0 at%, preferably from about 0.03 at% to about 1.7 at%, more preferably from about 0.05 at% to about 1.5 at%, still more preferably from about 0.07 at% to about 1.0 at%, relative to a total amount of M2.

[0051] In a preferred embodiment, the Ti-containing compound may be at least one selected from the group consisting of titanyl sulfate (TiOSC ), titanium oxide (TiOz), titanium hydroxide (Ti(OH)4), titanium ethoxide (Ti(OC2H5)4), and titanium propoxide (Ti(OC3H7)4). The Ti-containing compound may be preferably TiOSO4.

[0052] In a preferred embodiment, the content of the Ti-containing compound may be about 0.01 at% or more, preferably about 0.03 at% or more, more preferably about 0.05 at% or more, still more preferably about 0.07 at% or more, relative to a total amount of M2. The content of the Ti-containing compound may be about 2.0 at% or less, preferably about 1.7 at% or less, more preferably about 1.5 at% or less, still more preferably about 1.0 at% or less, relative to a total amount of M2. Specifically, the Ti-containing compound may be in a content from about 0.01 at% to about 2.0 at%, preferably from about 0.03 at% to about 1.7 at%, more preferably from about 0.05 at% to about 1.5 at%, still more preferably from about 0.07 at% to about 1.0 at%, relative to a total amount of M2.

[0053] In a preferred embodiment, the first Co-containing compound may be at least one selected from the group consisting of cobalt oxide (CO3O4), cobalt sulfate (COSO4), cobalt oxyhydroxide (CoOOH), cobalt acetate (Co(OOC(CH3))2), cobalt hydroxide (Co(OH)2), cobalt nitrate (CoCNCh ), cobalt carbonate (COCO3), cobalt chloride (C0CI2), and cobalt iodide (C0I2). The first Co-containing compound may be preferably Co(OH)2.

[0054] In a preferred embodiment, the content of the first Co-containing compound may be about 1.0 at% or more, preferably about 1.5 at% or more, more preferably about 1.7 at% or more, still more preferably about 2.0 at% or more, relative to a total amount of M2. The content of the first Co-containing compoundmay be about 4.0 at% or less, preferably about 3.5 at% or less, more preferably about 3.2 at% or less, still more preferably about 3.0 at% or less, relative to a total amount of M2. Specifically, the first Co-containing compound may be in a content from about 1.0 at% to about 4.0 at%, preferably from about 1.5 at% to about 3.5 at%, more preferably from about 1.7 at% to about 3.2 at%, still more preferably from about 2.0 at% to about 3.0 at%, relative to a total amount of M2.

[0055] In a preferred embodiment, the mixture may further comprise at least one compound containing an element selected from the group consisting of Y, Zr, Sb, Sr, Al, W, B, Ba, Ca, Cr, F, Fe, Mo, Si, V, Zn, Ti and S. Preferably, the mixture may further comprise a Y-containing compound. The Y-containing compound may be at least one selected from the group consisting of yttrium oxide (Y2O3), yttrium hydroxide (Y(OH)3), yttrium nitrate (Y(NO3)3), and yttrium acetate (Y(OOC(CH3))3). The Y-containing compound may be preferably Y2O3.

[0056] In a preferred embodiment, the step of heating the mixture is performed at a temperature between 600 °C and 1000 °C, preferably between 650 °C and 900 °C, more preferably between 700 °C and 800 °C, for about 5 to about 35 hours, preferably for about 10 to about 30 hours, more preferably about 15 to about 27 hours, still more preferably about 18 to about 26 hours. The step of heating the mixture may be performed under an oxygen atmosphere.Battery

[0057] In a third aspect, the present disclosure further provides a battery comprising the positive electrode active material powder as described herein.Use of Battery

[0058] In a fourth aspect, the present disclosure provides the use of the battery according to this disclosure, in an electrically powered device or system selected from the group consisting of: a portable computer, a tablet, a mobile phone, a telecommunication device, a power tool, mobile machinery, a robotic device, an energy storage system, an uninterruptible power supply system, an electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an extended-range electric vehicle, a fuel cell electric vehicle, a two-wheeler transportation system, a rail vehicle, a marine vessel, an aircraft, an aerospace system, a defense system, and a medical device.

[0059] As appreciated by a person skilled in the art, all embodiments directed to the cathode active material according to the first aspect may apply mutatis mutandis to the second, third and fourth aspect of the present disclosure. Additionally, this disclosure is intended to cover the combination of all embodiments listed above.EXPERIMENTAL ANALYSIS USED IN THE EXAMPLE AND THE COMPARATIVE EXAMPLES

[0060] The following analysis methods were used in the Example and the Comparative Examples.A) Inductively Coupled Plasma Optical - Emission spectroscopy (ICP-OES) analysis

[0061] The amount of Ni, Co, Mn, Al, Ti, W, Zr, Y, Sb, Sr, B, Ba, Ca, Cr, F, Fe, Mg, Mo, Si, V, Zn, and S in the positive electrode active material powder is measured with the ICP-OES method by using an Agilent ICP 720-OES (Agilent Technologies). 2 grams of powder sample is dissolved into 10 mL of high purity hydrochloric acid (HCI) (at least 37 wt% of HCI with respect to the total weight of solution) in an Erlenmeyer flask. The flask is covered by a glass and heated on a hot plate at 380 °C until complete dissolution of the precursor. After being cooled to room temperature, the solution of the Erlenmeyer flask is poured into a 250 mL volumetric flask. Afterwards, the volumetric flask is filled with deionized water up to the 250 mL mark, followed by complete homogenization.B) Particle size analysis

[0062] The particle size distribution (PSD) of the positive electrode active material powder is measured by laser diffraction particle size analysis using a Malvern Mastersizer 3000 with a Hydro MV wet dispersion accessory after having dispersed each of the powder samples in an aqueous medium. In order to improve the dispersion of the powder, sufficient ultrasonic irradiation and stirring are applied, and an appropriate surfactant is introduced. D50 is defined as the particle size at 50% of the cumulative volume% distributions.C) Field emission-scanning electron microscope (FE-SEM) measurement

[0063] The morphology and the primary particle size of the positive electrode active material are analyzed by FE-SEM technique. The measurement is performed with a JEOL JSM 7100F under a high vacuum environment of 9.6xl0'5Pa at 25 °C.D) Energy-dispersive X-ray spectroscopy (EDX) analysis

[0064] Using the sample of the positive electrode active materials, the carbon map is analyzed by EDX. The EDX is performed by JEOL JSM 7100F SEM equipment with a 50 mm2X-MaxN EDX sensor from Oxford instruments.E) Full cell testingE-l) Full cell preparation

[0065] 2000 mAh pouch-type cells are prepared as follows: the positive electrode active material powder, carbon (Super-P, Imerys Graphite & Carbon) as positive electrode conductive agents, and polyvinylidene fluoride (PVDF S5130, Solvay) as a positive electrode binder are added to N-methyl-2-pyrrolidone (NMP) as a dispersion medium so that the mass ratio of the positive electrode active material powder, the positive electrode conductive agents Super P, positive electrode binder is set at 95 / 3 / 2. Thereafter, the mixture is kneaded to prepare a positive electrode mixture slurry. The resulting positive electrode mixture slurry is then applied onto both sides of a positive electrode current collector, made of a 20 pm thick aluminum foil. The width of the applied area is 88.5 mm and the length is 425 mm. Typical loading weight of a positive electrode active material powder is about 14.8±1 mg / cm2. The electrode is then dried and calendared using pressure of 4.5 MPa. In addition, an aluminum plate serving as a positive electrode current collector tab is arc-welded to an end portion of the positive electrode.

[0066] Commercially available negative electrodes are used. In short, a mixture of artificial graphite, carbon (Super P, Imerys Graphite & Carbon), carboxy-methyl- cellulose-sodium, and styrene-butadiene-rubber, in a mass ratio of 95 / 1 / 1.5 / 2.5, is applied on both sides of a copper foil. A nickel plate serving as a negative electrode current collector tab is arc-welded to an end portion of the negative electrode. Typical loading weight of a negative electrode active material is about 10±l mg / m2.

[0067] Non-aqueous electrolyte is obtained by dissolving lithium hexafluorophosphate (LiPFe) salt at a concentration of 1.2 mol / L in a mixed solvent of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in a volume ratio of 1 : 1 : 1. It contains 1.0 wt% lithium difluorophosphate (UPO2F2), and 1.0 wt% vinylene carbonate (VC) as additives.

[0068] A sheet of the positive electrode, a sheet of the negative electrode, and a sheet of the microporous polymer separator (13 pm) interposed between them are spirally wound using a winding core rod in order to obtain a spirally wound electrodeassembly. The assembly and the electrolyte are then put in an aluminum laminated pouch in an air-dry room with dew point of -50 °C, so that the flat pouch-type lithium secondary battery is prepared. The design capacity of the secondary battery is 2000 mAh, when charged to 4.35 V. The full cell testing procedure uses a 1 C current definition of 2000 mA / g.E-2) Cycle life testA. Pre-charging and formation

[0069] The non-aqueous electrolyte solution is impregnated into the prepared dry battery for 8 hours at room temperature. The battery is pre-charged with the current of 0.25 C until 14% of its theoretical capacity and aged for a day at room temperature. The battery is then degassed using a pressure of -760 mmHg for 30 seconds, and the aluminum pouch is sealed. During measurement, the pouch is assembled in a press jig provided with silicon pad.

[0070] The battery is charged with a current of 0.2 C in CC mode (constant current) up to 4.2 V and CV mode (constant voltage) until a cut-off current of C / 20 is reached. The battery is discharged with a current of 0.2 C in CC mode down to 2.7 V. Then, it is fully charged with a current of 0.5 C in CC mode up to 4.2 V and CV mode until a cut-off current of C / 20 is reached.

[0071] Afterwards, the battery is discharged with a current of 0.5 C in CC mode down to 2.7 V. It is again charged with a current of 0.5 C in CC mode up to 4.2 V and CV mode until a cut-off current of C / 20 is reached. The final charging step is done in 25°C.B. Cycle life test

[0072] The lithium secondary full cell batteries are charged and discharged continuously under the following conditions at 45°C, to determine their chargedischarge cycle performance:- Charge is performed in CC mode under 1 C rate up to 4.2 V, then CV mode until C / 20 is reached,- The cell is then set to rest for 10 minutes,- Discharge is done in CC mode at 1 C rate down to 2.7 V,- The cell is then set to rest for 10 minutes,- The charge-discharge cycles proceed until 700 cycles. Every 100 cycles, the discharge is done at 0.1 C rate in CC mode down to 2.7 V.

[0073] The DCR is measured at 1.5 C for 10 s at the beginning of every 100 cycles repetition and the end of 700thcycle. The DCR. growth is calculated by the following formula :Discharge DCR at the 700 th cycle

[0074] The retention capacity is represented by the following equation :DQnRetention capacity (%) = - x 100DQi where DQi is a discharge capacity at the 1stcycle of full cell testing and DQnis a discharge capacity at the nthcycle of full cell testing.EXAMPLES and COMPARATIVE EXAMPLES

[0075] The present disclosure is further illustrated in the following examples.Example 1 (EXI)

[0076] The positive electrode active material powder EXI was obtained through the following steps:1) First mixing: a precursor having transition metal composition as Ni0.94Mn0.03Co0.03 in hydroxide or oxyhydroxide form was mixed homogeneously with ZrOz, AI2O3 and LiOH powder to prepare a first mixture, such that (i) the atomic ratio of Li to the total amount of Ni, Mn, and Co was 1.01, and (ii) Zr and Al were in contents of 0.15 at% and 0.34 at%, respectively, relative to the total amount of Ni, Mn, and Co in the precursor.2) First heating : the first mixture was heated at 830 °C for 6 hours and 740 °C for 5 hours 10 minutes under oxygen atmosphere followed by cooling, grinding and sieving to prepare a first mixed-metal oxide.3) Second mixing: the first mixed-metal oxide was mixed homogeneously with an aqueous solution containing COSO4 and MgSO4-7H2O, such that Co and Mg were in contents of 0.5 at% and 0.2 at%, respectively, relative to the total amount of Ni, Mn, and Co in the precursor to obtain a second mixture.4) Milling: the second mixture was bead-milled, followed by drying at 150 °C, for 15 hours under N2 atmosphere to prepare a milled material.5) Third mixing: the milled material was mixed homogeneously with Co(OH)2, and LiOH powder to prepare a third mixture, such that (i) the atomic ratio of Li to the total amount of Ni, Mn, and Co was 1.0, and (ii) Co was in a content of 2.0 at%, relative to the total amount of Ni, Mn, and Co in the milled material.6) Second heating: the third mixture was heated in 730 °C for 12 hours and 40 minutes under oxygen atmosphere followed by cooling, grinding and sieving to prepare EXI.Comparative example 1-1 (CEX1-1)

[0077] The positive electrode active material powder CEX1-1 was obtained through the same method as EXI, except that MgSO4-7H2O was not added in the second mixing step.Comparative example 1-2 (CEX1-2)

[0078] The positive electrode active material powder CEX1-2 was obtained through the same method as EXI, except that (i) MgSO4-7H2O was not added in the second mixing step, and (ii) Mg(OH)2 was added in the third mixing step, such that Mg was in a content of 0.2 at%, relative to the total amount of Ni, Mn, and Co in the milled material.Comparative example 1-3 (CEX1-3)

[0079] The positive electrode active material powder CEX1-3 was obtained through the same method as EXI, except that (i) MgSO4-7H2O was not added in the second mixing step, and that (ii) (NH4)6Mo?O24-4H2O was added in the third mixing step, such that Mo was in a content of 0.2 at%, relative to the total amount of Ni, Mn, and Co in the milled material.Comparative example 1-4 (CEX1-4)

[0080] The positive electrode active material powder CEX1-4 was obtained through the same method as EXI, except that (i) MgSO4-7H2O was not added in the second mixing step, and that (ii) Y2(SO4)3 was added in the third mixing step, such that Y was in a content of 0.2 at%, relative to the total amount of Ni, Mn, and Co in the milled material.Example 2 (EX2)

[0081] The positive electrode active material powder EX2 was obtained through the same method as EXI, except that CoSO4 was not added in the second mixing step.Comparative example 2-1 (CEX2-1)

[0082] The positive electrode active material powder CEX2-1 was obtained through the same method as EX2, except that MgSO4-7H2O was not added in the second mixing step.Comparative example 2-2 (CEX2-2)

[0083] The positive electrode active material powder CEX2-3 was obtained through the same method as EX2, except that (i) MgSO4-7H2O was not added in the second mixing step, and (ii) (NH4)6Mo7O24-4H2O was added in the second mixing step, such that Mo was in a content of 0.2 at%, relative to the total amount of Ni, Mn, and Co in the precursor.Comparative example 2-3 (CEX2-3)

[0084] The positive electrode active material powder CEX2-3 was obtained through the same method as EX2, except that (i) MgSO4-7H2O was not added in the second mixing step, and (ii) TiOSO4 was added in the second mixing step, such that Ti was in a content of 0.2 at%, relative to the total amount of Ni, Mn, and Co in the precursor.Comparative example 2-4 (CEX2-4)

[0085] The positive electrode active material powder CEX2-4 was obtained through the same method as EX2, except that (i) MgSO4-7H2O was not added in the second mixing step, and (ii) Al2(SO4)3-7H2O was added in the second mixing step, such that Al was in a content of 0.2 at%, relative to the total amount of Ni, Mn, and Co in the precursor.Comparative example 2-5 (CEX2-5)

[0086] The positive electrode active material powder CEX2-5 was obtained through the same method as EX2, except that (i) MgSO4-7H2O was not added in the second mixing step, and (ii) Y2(SO4)3-8H2O was added in the second mixing step in a content of 0.2 at%, relative to the total amount of Ni, Mn, and Co in the precursor.Comparative example 3-1 (CEX3-1)

[0087] The positive electrode active material powder CEX3-1 was obtained through the same method as CEX2-1, except that Mg(OH)2powder was added in the third mixing step such that Mg was in a content of 0.2 at%, relative to the total amount of Ni, Mn, and Co in the milled material.Comparative example 3-2 (CEX3-2)

[0088] The positive electrode active material powder CEX3-1 was obtained through the same method as CEX2-1, except that (NH4)6Mo7O24-4H2O was added in the third mixing step such that Mo was in a content of 0.2 at%, relative to the total amount of Ni, Mn, and Co in the milled material.Comparative example 3-3 (CEX3-3)

[0089] The positive electrode active material powder CEX3-3 was obtained through the same method as CEX3-1, except that Y2(SO4)3 powder was added in the third mixing step such that Y was in a content of 0.2 at%, relative to the total amount of Ni, Mn, and Co in milled material.

[0090] Table 1 below shows the compositions of EXI and EX2 measured with the ICP-OES.Table 1. Compositions of EXI and EX2*Me is the metals other than Li.

[0091] Table 2 below shows the DCR growth at 45°C from the 1stcycle to the 700thcycle for EXs and CEXs.Table 2. Summary of the DCR. growth at 45°C

[0092] Table 3 below shows the retention capacity at 45 °C from the 1stcycle to the 700thcycle for EXs and CEXs.Table 3. Summary of the retention capacity at 45 °C

[0093] Figure 1 is a graph based on the data of Table 2, showing the DCR growth at 45°C according to the cycle number for EXI, CEX1-1 to CEX1-3, and CEX1- 4. Figure 4 is a graph based on the data of Table 3, showing the retention capacity at 45°C according to the cycle number for EXI, CEX1-1 to CEX1-3, and CEX1-4. Referring to Figures 1 and 4, EXI exhibited better electrochemical performances of the DCR growth and the retention capacity, compared to CEX1-1 to CEX1-3, and CEX1-4. In particular, even though EXI and CEX1-2 had both Mg in each of them, EXI, prepared by being milled with a solution comprising Mg, exhibited better performances compared to CEX1-2, prepared by being heated with a powder comprising Mg. Thus, the advanced effects of the positive electrode active material powder according to the present disclosure is confirmed.

[0094] Figure 2 is a graph based on the data of Table 2, showing the DCR growth at 45°C according to the cycle number for EX2, CEX2-1 to CEX2-4, and CEX2-5. Figure 5 is a graph based on the data of Table 3, showing the retention capacity at 45°C according to the cycle number for EX2, CEX2-1 to CEX2-4, and CEX2-5. Referring to Figures 2 and 5, EX2 exhibited better electrochemical performances of the DCR growth and the retention capacity, compared to CEX2-1 to CEX2-4, andCEX2-5. Thus, the advanced effects of the positive electrode active material powder according to the present disclosure is confirmed.

[0095] Figure 3 is a graph based on the data of Table 2, showing the DCR growth at 45°C according to the cycle number for EX2, CEX3-1, CEX3-2, and CEX3- 3. Figure 6 is a graph based on the data of Table 3, showing the retention capacity at 45°C according to the cycle number for EX2, CEX3-1, CEX3-2, and CEX3-3. Referring to Figures 3 and 6, EX2 exhibited better electrochemical performances of the DCR growth and the retention capacity, compared to CEX3-1, CEX3-2, and CEX3- 3. In particular, even though EX2 and CEX3-1 had both Mg, EX2, prepared by being milled with a solution comprising Mg, exhibited better performances compared to CEX3-1, prepared by being heated with a powder comprising Mg. Thus, the advanced effects of the positive electrode active material powder according to the present disclosure is confirmed.

[0096] Furthermore, comparing EXI and EX2 based on the data of Tables 2 and 3, the electrochemical performances of EX2, wherein only Mg-containing compound was added during the milling step, are comparable to EXI, wherein both Mg- containing compound and Co-containing compound were added during the milling step. Thus, Mg may be essential and Co may be optional during the milling step to achieve the advanced effects of the present disclosure.

[0097] Figure 7 and Figure 8 are images of CEX1-2 and EXI, respectively, taken with FE-SEM EDX at a magnification of 5,000. Agglomeration of Mg was observed in Figure 7, while homogeneous distribution of Mg was observed in Figure 8. Accordingly, the positive electrode active material powder, prepared by being milled with a solution comprising Mg, may exhibit homogeneous distribution of Mg on its surface, leading to improvement in electrochemical performances, such as lower DCR growth and higher retention capacity.

Claims

CLAIMS

1. A method for preparing a positive electrode active material powder for Li-ion rechargeable batteries, comprising the following steps:1) mixing a Li source and a transition metal composite precursor to obtain a preliminary mixture,2) heating the preliminary mixture to obtain a mixed-metal oxide,3) milling the mixed-metal oxide with a solution comprising a Mg-containing compound to obtain a milled material,4) mixing the milled material with a first Co-containing compound to obtain a mixture, and5) heating the mixture to obtain the positive electrode active material powder; wherein the positive electrode active material powder comprises monolithic particles comprising Li, Ml, and 0, wherein Ml consists of:Ni in an atomic content xl, wherein 70.0 at% < xl < 100.0 at%, relative to a total amount of Ml;Mn in an atomic content yl, wherein 1.0 at% < yl < 10.0 at%, relative to a total amount of Ml;Co in an atomic content zl, wherein 1.0 at% < zl < 10.0 at%, relative to a total amount of Ml;Mg in an atomic content al, wherein 0.01 at% < al < 3.0 at%, relative to a total amount of Ml;DI in an atomic content dl, wherein 0.00 at% < dl < 7.0 at%, relative to a total amount of Ml, wherein Dl is at least one element other than Li, Ni, Mn, Co, Mg, and O, wherein xl+yl+zH-al-i-dl is 100.0 at%, wherein xl, yl, zl, al, and dl are determined by Inductively Coupled Plasma Optical - Emission spectroscopy.

2. The method according to claim 1, wherein the step of milling the mixed- metal oxide is performed by using a bead mill.

3. The method according to claim 1 or 2, wherein 0.01 at% < al < 2.0 at%, preferably 0.03 at% < al < 1.5 at%, more preferably 0.05 at% < al < 1.0 at%, still more preferably 0.07 at% < al < 0.5 at%, relative to a total amount of Ml.

4. The method according to any of the claims 1 to 3, wherein the solution of step 3) further comprises a second Co-containing compound.

5. The method according to claim 4, wherein the second Co-containing compound is selected from cobalt sulfate (COSO4), cobalt oxyhydroxide (CoOOH), cobalt oxide (CO3O4), cobalt acetate (Co(OOC(CH3))2), cobalt hydroxide (Co(OH)2), cobalt nitrate (Co(NO3)2), cobalt carbonate (COCO3), cobalt chloride (C0CI2), and cobalt iodide (C0I2).

6. The method according to any of the claims 1 to 5, wherein the solution of step 3) further comprises an Al-containing compound and / or a Ti-containing compound.

7. The method according to any of the claims 1 to 6, wherein DI is at least one selected from the group consisting of Al, Zr, Ti, W, Sr, B, Ba, Ca, Cr, F, Fe, Sb, Si, Y, V, Zn, and S, preferably at least one of Al, Zr, and Ti.

8. The method according to any of the claims 1 to 7, wherein the Mg- containing compound is selected from magnesium sulfate heptahydrate (MgSO4-7H2O), magnesium sulfate (MgSO4), magnesium acetate (Mg(CH3COO)2), magnesium nitrate (MgCNC ), magnesium oxide (MgO), and magnesium chloride (MgCI2).

9. The method according to any of the claims 1 to 8, wherein 75.0 at% < xl < 99.0 at%, preferably 80.0 at% < xl < 98.0 at%, more preferably 85.0 at% < xl < 97.0 at%, still more preferably 87.0 at% < xl < 96.0 at%, relative to a total amount of Ml.

10. The method according to any of the claims 1 to 9, wherein the step of heating the mixture is performed at a temperature between 600 °C and 1000 °C, preferably between 650 °C and 900 °C, more preferably between 700 °C and 800 °C.

11. The method according to any of the claims 1 to 10, wherein the step of heating the preliminary mixture is performed at a temperature between 600 °C and 1000 °C, preferably between 700 °C and 950 °C, more preferably .

12. The method according to any of the claims 1 to 11, wherein the preliminary mixture comprises Li, M3, and O, wherein M3 consist of, Ni in an atomic content x3, wherein about 70.0 at% < x3 < 100.0 at%, relative to a total amount of M3, Mn in an atomic content y3, wherein 0.0 at% < y3 < about10.0 at%, relative to a total amount of M3, Co in an atomic content z3, wherein 0.0 at% < z3 < about 10.0 at%, relative to a total amount of M3, D3 in an atomic content d3, wherein 0.00 at% < d3 < about 10.0 at%, relative to a total amount of M3, wherein D3 is at least one element other than Li, Ni, Mn, Co, and O, wherein x3+y3+z3+a3+d3 is 100.0 at%, and wherein x3, y3, z3, a3, and d3 are determined by ICP-OES.

13. A positive electrode active material obtainable by a method according to any of the claims 1 to 12.

14. A battery comprising the positive electrode active material powder according to claim 13.

15. Use of the battery according to claim 14 in an electrically powered device or system selected from the group consisting of: a portable computer, a tablet, a mobile phone, a telecommunication device, a power tool, mobile machinery, a robotic device, an energy storage system, an uninterruptible power supply system, an electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an extended-range electric vehicle, a fuel cell electric vehicle, a two-wheeler transportation system, a rail vehicle, a marine vessel, an aircraft, an aerospace system, a defense system, and a medical device.

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