Blended positive electrode active material powder

Abstract

The present disclosure provides a blended positive electrode active material powder for Li-ion rechargeable batteries, comprising a first positive electrode active material powder and a second positive electrode active material powder, wherein the first positive electrode active material powder consists of first particles comprising Li, M1, and O, wherein M1 comprises Ni in a content x1 in at%, relative to a total amount of M1, wherein the second positive electrode active material powder consists of second particles comprising Li, M2, and O, wherein M2 comprises Ni in a content x2 in at%, relative to a total amount of M2, wherein x1 and x2 are measured by ICP-OES, wherein x2-x1 ≥ about 5.0 at%, wherein each of the first particles consists of at least one primary particle and at most twenty primary particles, wherein each of the second particles consists of at least one primary particle and at most twenty primary particles, and wherein a content of the first particles in wt%, relative to a total weight of the first and second particles, ranges from about 55 wt% to about 65 wt%.

Description

DESCRIPTIONTitleBLENDED POSITIVE ELECTRODE ACTIVE MATERIAL POWDERTECHNICAL FIELD

[0001] The present disclosure concerns a blended positive electrode active material powder for lithium (Li) ion rechargeable batteries. The present disclosure further concerns a method for preparing the blended positive electrode active material powder, a battery comprising the blended positive electrode active material powder, and a 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 high capacity, high energy density, low resistance, etc.

[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.

[0004] Lu, et al. "Single-Crystal Nickel-Based Cathodes: Fundamentals and Recent Advances", Electrochemical Energy Reviews, 5, 15 (2022) describes that single-crystal materials can maintain their morphological integrity in the absence of anisotropic forces even if operated under extreme conditions, thus reducing gas evolution during electrochemical cycling. However, there is still room for improving the electrochemical performance of Li-ion rechargeable batteries that adopt single crystal particles or monolithic particles. Monolithic particles are hereby defined as particles consisting of at least one primary particle and at most twenty primary particles.

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

[0006] The present disclosure provides a blended positive electrode active material powder for Li-ion rechargeable batteries, comprising a first positive electrode active material powder and a second positive electrode active material powder, wherein the first positive electrode active material powder consists of first particles comprising Li, Ml, and 0, wherein Ml comprises Ni in a content xl in at%, relative to a total amount of Ml; wherein Ml consists of:Ni, wherein 70.0 at% < xl < 95.0 at%, relative to a total amount of Ml;Mn in a content yl, wherein 1.0 at% < yl < 10.0 at%, relative to a total amount of Ml;Co in a content zl, wherein 4.0 at% < zl < 15.0 at%, relative to a total amount of Ml; andDI in a content dl, wherein 0.00 at% < dl < 5.0 at%, relative to a total amount of Ml, wherein Dl is at least one element other than Li, Ml, and O, wherein yl, zl, and dl are measured by ICP-OES, and wherein xl+yl+zl+dl is 100.0 at%; wherein the second positive electrode active material powder consists of second particles comprising Li, M2, and O, wherein M2 comprises Ni in a content x2 in at%, relative to a total amount of M2; wherein M2 consists of:Ni, wherein 75.0 at% < x2 < 100.0 at%, relative to a total amount of M2;Mn in a content y2, wherein 0.0 at% < y2 < 8.0 at%, relative to a total amount of M2;Co in a content z2, wherein 0.0 at% < z2 < 13.0 at%, relative to a total amount of M2; andD2 in a content d2, wherein 0.0 at% < d2 < 4.0 at%, relative to a total amount of M2, wherein D2 is at least one element other than Li, M2, and O,wherein y2, z2, and d2 are measured by ICP-OES, and wherein x2+y2+z2+d2 is 100.0 at%; wherein xl and x2 are measured by ICP-OES, wherein x2-xl > 5.0 at%, wherein each of the first particles consists of at least one primary particle (PPI) and at most twenty primary particles (PPI), determined by SEM image analysis; wherein each of the second particles consists of at least one primary particle (PP2) and at most twenty primary particles (PP2), determined by SEM image analysis; and wherein a content of the first particles in wt%, relative to a total weight of the first and second particles, ranges from 55 wt% to 65 wt%.

[0007] The present inventors have found that the electrochemical performance of Li-ion rechargeable batteries may be enhanced by employing the blended positive electrode active material powder according to the present disclosure. Specifically, the blended positive electrode active material powder formed by blending a first monolithic positive electrode active material powder (Pl) and a second monolithic positive electrode active material powder (P2), wherein the Ni content of P2 is higher than that of Pl by about 5.0 at% or more, and wherein a weight ratio of Pl relative to a total weight of the blended positive electrode active material powder ranges from about 55 wt% to about 65 wt%, may exhibit higher charge / discharge capacity, lower direct current resistance (DCR.) growth after repeated charging / discharging cycles, and higher energy density, in particular compared to (i) a monolithic positive electrode active material powder with an almost single Ni content identical to the average Ni content of the blended positive electrode active material powder, and (ii) a blended positive electrode active material powder with a weight ratio of Pl, relative to a total weight of the blended positive electrode active material powder, being lower than about 55 wt% or higher than about 65 wt%.

[0008] The present disclosure provides a method for preparing a blended positive electrode active material powder for Li-ion rechargeable batteries, preferably the blended positive electrode active material powder according to the present disclosure.

[0009] The present disclosure provides a battery, in particular a Li ion rechargeable battery, comprising the blended positive electrode active materialpowder according to any embodiment or combination of embodiments of the present disclosure.

[0010] The present disclosure provides a use of the battery of the present disclosure comprising the blended positive electrode active material powder according to any embodiment or combination of embodiments of the present disclosure.DETAILED DESCRIPTION OF THE DISCLOSURE

[0011] 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.

[0012] "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.

[0013] "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.

[0014] "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 particle may be determined by counting the primary particles observed in a Scanning Electron Microscope (SEM) image at a magnification of 2000 from a top view, where the whole shape of the monolithic particle is taken. In the context of the present disclosure, primary particles may bedistinguished 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.

[0015] "D50" as used herein refers to a particle size at 50% of cumulative volume% distribution when measured by laser scattering method. The method of measuring D50 by laser scattering method is described herein below.

[0016] As used herein, a range of values "from X to Y" and "between X and Y" include the endpoints of X and Y.

[0017] "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.Blended Positive Electrode Active Material Powder

[0018] In a preferred embodiment, Ml consists of: nickel (Ni), wherein about 70.0 at% < xl < about 95.0 at%, relative to a total amount of Ml; manganese (Mn) in a content yl, wherein about 1.0 at% < yl < about 10 at%, relative to a total amount of Ml; cobalt (Co) in a content zl, wherein about 4.0 at% < zl < about 15.0 at%, relative to a total amount of Ml; andDI in a content dl, wherein 0.00 at% < dl < about 5.0 at%, relative to a total amount of Ml, wherein Dl is at least one element other than Li, Ml, and O, wherein yl, zl, and dl are measured by ICP-OES, and wherein xl+yl+zl+dl is 100 at%.

[0019] In a preferred embodiment, Dl is at least one element selected from the group consisting of aluminum (Al), zirconium (Zr), boron (B), tungsten (W), strontium (Sr), antimony (Sb), titanium (Ti), barium (Ba), calcium (Ca), chromium (Cr), fluorine (F), iron (Fe), magnesium (Mg), molybdenum (Mo), silicon (Si), yttrium (Y), vanadium (V), zinc (Zn), and sulfur (S). Dl is preferably at least one element selected from the group consisting of Al, Zr, B and W.

[0020] In a preferred embodiment, xl may be about 80.0 at% or more, preferably about 82.0 at% or more, more preferably about 84.0 at% or more, stillmore preferably about 85.0 at% or more, relative to a total amount of Ml, and xl may be about 94.0 at% or less, preferably about 93.0 at% or less, more preferably about 92.0 at% or less, still more preferably about 91.0 at% or less, relative to a total amount of Ml. Specifically, the range of xl may be: wherein 80.0 at% < xl < 94.0 at%, preferably 82.0 at% < xl < 93.0 at%, more preferably 84.0 at% < xl < 92.0 at%, still more preferably 85.0 at% < xl < 91.0 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.

[0021] In a preferred embodiment, yl may be about 1.1 at% or more, preferably about 1.2 at% or more, more preferably about 1.3 at% or more, still more preferably about 1.4 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 1.1 at% < yl < about 9.0 at%, preferably about 1.2 at% < yl < about 8.0 at%, more preferably about 1.3 at% < yl < about 7.0 at%, still more preferably about 1.4 at% < yl < about 6.0 at%, relative to a total amount of Ml. Without wishing to be bound by any theory, if yl is more 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.

[0022] In a preferred embodiment, zl may be about 4.2 at% or more, preferably about 4.4 at% or more, more preferably about 4.5 at% or more, still more preferably about 4.6 at% or more, relative to a total amount of Ml, and zl may be about 13.0 at% or less, preferably about 11.0 at% or less, more preferably about 10.0 at% or less, still more preferably about 9.0 at% or less, relative to a total amount of Ml. Specifically, the range of zl may be: about 4.2 at% < zl < about 13.0 at%, preferably about 4.4 at% < zl < about 11.0 at%, more preferably about 4.5 at% < zl < about 10.0 at%, still more preferably about 4.6 at% < zl < about 9.0 at%, relative to a total amount of Ml. Without wishing to be bound by any theory, if zl is more than about 15.0 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.

[0023] In a preferred embodiment, dl may be about 0.05 at% or more, preferably about 0.10 at% or more, more preferably about 0.20 at% or more, still more preferably about 0.25 at% or more, relative to a total amount of Ml, and dl may be about 4.0 at% or less, preferably about 3.5 at% or less, more preferably about 3.0 at% or less, still more preferably about 2.5 at% or less, relative to a total amount of Ml. Specifically, the range of dl may be: about 0.05 at% < dl < about 4.0 at%, preferably about 0.10 at% < dl < about 3.5 at%, more preferably about 0.20 at% < dl < about 3.0 at%, still more preferably about 0.25 at% < dl < about 2.5 at%, relative to a total amount of Ml.

[0024] In an embodiment of the present disclosure, the Li / Ml atomic ratio in the first positive electrode active material powder ranges from 0.90 to 1.10. In certain embodiments, the Li / Ml atomic ratio may be at least 0.92, or at least 0.95. In certain embodiments the Li / Ml atomic ratio may be at most 1.08 or at most 1.05. In certain embodiments the Li / Ml ratio ranges from 0.92 to 1.08 or from 0.95 to 1.05.

[0025] In an embodiment of the present disclosure, the O / Ml atomic ratio in the first positive electrode active material powder is about 2.

[0026] In a preferred embodiment, M2 consists of:Ni, wherein about 75.0 at% < x2 < 100.0 at%, relative to a total amount of M2; Mn in a content y2, wherein 0.0 at% < y2 < about 8.0 at%, relative to a total amount of M2;Co in a content z2, wherein 0.0 at% < z2 < about 13.0 at%, relative to a total amount of M2; andD2 in a content d2, wherein 0.00 at% < d2 < about 4.0 at%, relative to a total amount of Ml, wherein D2 is at least one element other than Li, M2, and O, wherein y2, z2, and d2 are measured by ICP-OES, and wherein x2+y2+z2+d2 is 100.0 at%.

[0027] In a preferred embodiment, D2 is at least one element selected from the group consisting of Al, Zr, B, W, Sr, Sb, Ti, Ba, Ca, Cr, F, Fe, Mg, Mo, Si, Y, V, Zn, and S. D2 is preferably at least one element selected from the group consisting of Al, Zr, B and W.

[0028] In a preferred embodiment, x2 may be about 85.0 at% or more, preferably about 88.0 at% or more, more preferably about 90.0 at% or more, still more preferably about 92.0 at% or more, relative to a total amount of M2, and x2 may be less than about 100.0 at%, preferably about 99.0 at% or less, more preferably about 98.0 at% or less, still more preferably about 97.0 at% or less, relative to a total amount of M2. Specifically, the range of x2 may be: wherein 85.0 at% < x2 < 100.0 at%, preferably 88.0 at% < x2 < 99.0 at%, more preferably 90.0 at% < x2 < 98.0 at%, still more preferably 92.0 at% < x2 < 97.0 at%, relative to a total amount of M2. Without wishing to be bound by any theory, if x2 is less than about 75.0 at%, relative to a total amount of M2, the capacity and the energy density may not be sufficient.

[0029] In a preferred embodiment, y2 may be about 0.1 at% or more, preferably about 0.2 at% or more, more preferably about 0.3 at% or more, still more preferably about 0.4 at% or more, relative to a total amount of Ml, and yl may be about 6.0 at% or less, preferably about 4.0 at% or less, more preferably about 3.0 at% or less, still more preferably about 2.0 at% or less, relative to a total amount of M2. Specifically, the range of y2 may be: about 0.1 at% < y2 < about 6.0 at%, preferably about 0.2 at% < y2 < about 4.0 at%, more preferably about 0.3 at% < y2 < about 3.0 at%, still more preferably about 0.4 at% < y2 < about 2.0 at%, relative to a total amount of M2. Without wishing to be bound by any theory, if y2 is more than about 8.0 at%, relative to a total amount of M2, the Li-ion rechargeable batteries may suffer from structural instability resulting in poor cycling stability.

[0030] In a preferred embodiment, z2 may be about 0.5 at% or more, preferably about 1.0 at% or more, more preferably about 1.5 at% or more, still more preferably about 2.0 at% or more, relative to a total amount of M2, and z2 may be about 10.0 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 10.0 at%, preferably about 1.0 at% < z2 < about 8.0 at%, more preferably about 1.5 at% < z2 < about 7.0 at%, still more preferably about 2.0 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 13.0 at%, relative to a total amount of M2, side reactions between the blended positive electrode active material powder and the electrolyte solutionmay be promoted to deteriorate the electrochemical performance of the Li-ion rechargeable batteries.

[0031] In a preferred embodiment, d2 may be about 0.05 at% or more, preferably about 0.10 at% or more, more preferably about 0.15 at% or more, still more preferably about 0.20 at% or more, relative to a total amount of M2, and d2 may be about 4.0 at% or less, preferably about 3.5 at% or less, more preferably about 3.0 at% or less, still more preferably about 2.5 at% or less, relative to a total amount of M2. Specifically, the range of d2 may be: about 0.05 at% < d2 < about 4.0 at%, preferably about 0.10 at% < d2 < about 3.5 at%, more preferably about 0.15 at% < d2 < about 3.0 at%, still more preferably about 0.20 at% < d2 < about 2.5 at%, relative to a total amount of M2.

[0032] In an embodiment of the present disclosure, the Li / M2 atomic ratio in the second positive electrode active material powder ranges from 0.90 to 1.10. In certain embodiments, the Li / M2 atomic ratio may be at least 0.92, or at least 0.95. In certain embodiments the Li / M2 atomic ratio may be at most 1.08 or at most 1.05. In certain embodiments the Li / M2 ratio ranges from 0.92 to 1.08 or from 0.95 to 1.05.

[0033] In an embodiment of the present disclosure, the O / M2 atomic ratio in the second positive electrode active material powder is about 2.

[0034] In a preferred embodiment, x2-xl may be about 5.5 at% or more, preferably about 6.0 at% or more, more preferably about 6.5 at% or more, and x2- xl may be about 20.0 at% or less, preferably about 15.0 at% or less, more preferably about 13.0 at% or less, still more preferably about 10.0 at% or less. Specifically, the range of x2-xl may be: 5.5 at% < x2-xl < 20.0 at%, preferably 6.0 at% < x2-xl < 15.0 at%, more preferably 6.5 at% < x2-xl < 13.0 at%, still more preferably 6.5 at% < x2-xl < 10.0 at%. The blended positive electrode active material powder, with x2-xl being 5.0 at% or more, may exhibit enhanced electrochemical performance, such as higher charge / discharge capacity, lower DCR growth after repeated charging / discharging cycles, and higher energy density, compared to a monolithic positive electrode active material powder with an almost single Ni content identical to the average Ni content of the blended positive electrode active material powder.

[0035] In a preferred embodiment, the content of the first particles in wt%, relative to a total weight of the first and second particles may be about 56 wt% or more, preferably about 57 wt% or more, more preferably about 58 wt% or more, still more preferably about 59 wt% or more, and may be about 64 wt% or less, preferably about 63 wt% or less, more preferably about 62 wt% or less, still more preferably about 61 wt% or less. Specifically, the content of the first particles in wt%, relative to a total weight of the first and second particles may range from about 56 wt% to about 64 wt%, preferably from about 57 wt% to about 63 wt%, more preferably from about 58 wt% to about 62 wt%, still more preferably from about 59 wt% to about 61 wt%. Without wishing to be bound by any theory, if the content of the first particles in wt%, relative to a total weight of the first and second particles, is less than about 55 wt% or greater than about 65 wt%, the charge / discharge capacity after repeated charging / discharging cycles and the energy density may be decreased, compared to the blended positive electrode active material powder according to the present disclosure.

[0036] In an embodiment of the present disclosure, the Li / (M1 + M2) atomic ratio in the blended positive electrode active material powder ranges from 0.90 to 1.10. In certain embodiments, the U / (M1 + M2)atomic ratio may be at least 0.92, or at least 0.95. In certain embodiments the Li / (M1 + M2)atomic ratio may be at most 1.08 or at most 1.05. In certain embodiments the Li / (M1 + M2) ratio ranges from 0.92 to 1.08 or from 0.95 to 1.05.

[0037] In an embodiment of the present disclosure, the O / (M1 + M2) atomic ratio in the blended positive electrode active material powder is about 2.

[0038] In a preferred embodiment, D50 of the first particles may be about 1.0 pm or more, preferably about 1.5 pm or more, more preferably about 2.0 pm or more, still more preferably about 2.5 pm or more, and D50 of the first particles may be about 8.0 pm or less, preferably about 7.5 pm or less, more preferably about 7.0 pm or less, still more preferably about 6.5 pm or less. Specifically, D50 of the first particles may range from about 1.0 pm to about 8.0 pm, preferably from about 1.5 pm to about 7.5 pm, more preferably from about 2.0 pm to about 7.0 pm, still more preferably from about 2.5 pm to about 6.5 pm. Without wishing to be bound by any theory, if D50 of the first particles is less than about 1.0 pm, the first particles may agglomerate to form clusters, leading to poor contact with the electrolyte, and if D50of the first particles is more than about 8.0 pm, the energy density may be lowered due to decreased packing density.

[0039] In a preferred embodiment, D50 of the second particles may be equal to or larger than D50 of the first particles. Specifically, D50 of the second particles may be about 1.0 pm or more, preferably about 1.5 pm or more, more preferably about 2.0 pm or more, still more preferably about 2.5 pm or more, and D50 of the second particles may be about 12.0 pm or less, preferably about 10.0 pm or less, more preferably about 8.0 pm or less, still more preferably about 7.0 pm or less. More specifically, D50 of the second particles may range from about 1.0 pm to about 12.0 pm, preferably from about 1.5 pm to about 10.0 pm, more preferably from about 2.0 pm to about 8.0 pm, still more preferably from about 2.5 pm to about 7.0 pm. Without wishing to be bound by any theory, if D50 of the second particles is less than about 1.0 pm, the second particles may agglomerate to form clusters, leading to poor contact with the electrolyte, and if D50 of the second particles is more than about 12.0 pm, the energy density may be lowered due to decreased packing density.Method for Preparing Positive Electrode Active Material Powder

[0040] The present disclosure provides a method for preparing a blended positive electrode active material powder for Li-ion rechargeable batteries, preferably the blended positive electrode active material powder according to the present disclosure, comprising: a. preparing a first positive electrode active material powder, b. preparing a second positive electrode active material powder, and c. mixing the first and second positive electrode active material powders to obtain the blended positive electrode active material powder, wherein the step of preparing the first positive electrode active material powder comprises: a.l providing a first starting material comprising a Li source and a first transition metal composite precursor comprising M3, wherein M3 comprises Ni in a content x3 in at%, relative to a total amount of M3; a.2 heating the first mixture at a temperature between about 600 °C and about 1000 °C to obtain a first heated material; a.3 providing a first intermediate material comprising the first heated material;a.4 milling the first intermediate material to obtain a first milled material; a.5 providing a first mixture comprising the first milled material; and a.6 heating the first mixture at a temperature between about 500°C and about 900 °C, wherein the step of preparing the second positive electrode active material powder comprises: b.l providing a second starting material comprising a Li source and a second transition metal composite precursor comprising M4, wherein M4 comprises Ni in a content x4 in at%, relative to a total amount of M4; b.2 heating the second starting material at a temperature between about 600 °C and about 1000 °C to obtain a second heated material; b.3 providing a second intermediate material comprising the second heated material; b.4 milling the second intermediate material to obtain a second milled material; b.5 providing a second mixture comprising the second milled material; and b.6 heating the second mixture at a temperature between about 500 °C and about 900 °C, wherein x4-x3 > about 5.0 at%, and wherein a content of the first positive electrode active material powder in wt%, relative to a total weight of the blended positive electrode active material powder, ranges from about 55 wt% to about 65 wt%.

[0041] Any suitable transition metal composite precursor may be used herein. For example, each of the first and second transition metal composite precursors may be (oxy) hydroxide or oxide comprising Ni. Each of the first and second transition metal composite precursors may comprise optionally Mn, optionally Co, and optionally combinations thereof. In each of the first and second transition metal composite precursors, the content of Ni relative to the total amount of the transition metals in the precursor may be 70.0 at% or more, preferably 75.0 at% or more, more preferably 80.0 at% or more, still more preferably 85.0 at% or more.

[0042] The Li source may be lithium hydroxide (LiOH), lithium hydroxide monohydrate (LiOH-H2O) 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.

[0043] In a preferred embodiment, x3 may be about 80.0 at% or more, preferably about 82.0 at% or more, more preferably about 84.0 at% or more, still more preferably about 85.0 at% or more, relative to a total amount of M3, and x3 may be about 95.0 at% or less, preferably about 94.0 at% or less, more preferably about 93.0 at% or less, still more preferably about 92.0 at% or less, relative to a total amount of M3. Specifically, the range of x3 may be: wherein about 80.0 at% < x3 < about 95.0 at%, preferably about 82.0 at% < x3 < about 94.0 at%, more preferably about 84.0 at% < x3 < about 93.0 at%, still more preferably about 85.0 at% < x3 < 92.0 at%, relative to a total amount of M3. Without wishing to be bound by any theory, if x3 is less than about 80.0 at%, relative to a total amount of M3, the capacity and the energy density may not be sufficient.

[0044] In a preferred embodiment, the first starting material and / or the second starting material 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, Mg, Mo, Si, V, Zn, Ti and S. Preferably, the first and second starting materials may further comprise a Zr-containing compound. The Zr-containing compound may be at least one selected from the group consisting of zirconium oxide (ZrO2), zirconium hydroxide (Zr(OH)4), zirconium ethoxide (Zr(OC2Hs)4), and zirconium propoxide (Zr(OC3H7)4), preferably ZrO2.

[0045] In a preferred embodiment, the step of heating the first starting material may be performed at a temperature preferably between about 650 °C and about 960 °C, more preferably between about 700 °C and about 850 °C, for about 5 to about 20 hours, preferably for about 6 to about 18 hours, more preferably about 7 to about 16 hours, still more preferably about 8 to about 15 hours. The step of heating the first mixture may be performed under an oxygen atmosphere.

[0046] In a preferred embodiment, the first intermediate material may further comprise a solution comprising a Co-containing compound. The Co-containing compound may be at least one selected from the group consisting of cobalt sulfate (COSO4), cobalt oxyhydroxide (CoOOH), cobalt oxide (CO3O4), cobalt acetate (CO(OOC(CH3))2), cobalt hydroxide (Co(OH)2), cobalt nitrate (CoCNC ), cobalt carbonate (COCO3), cobalt chloride (C0CI2), and cobalt iodide (C0I2), and the Cocontaining compound may be preferably COSO4. The content of the 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 M3. The content of the 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 M3. Specifically, the 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 M3.

[0047] In a preferred embodiment, the step of milling the first intermediate material 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 ZrO2, 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 rotation speed may range from about 100 rpm to about 10000 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.

[0048] In a preferred embodiment, at least one of the first and second mixture may further comprise at least one compound comprising at least one element selected from the group consisting of Co, Al, Zr, Ti, W, Sr, B, Ba, Ca, Cr, F, Fe, Sb, Si, Y, V, and Zn, preferably at least one of Co, Al, Zr, B, W and Ti. At least one of the first and second mixture may further comprise a Co-containing compound, and / or aZr-containing compound. The Co-containing compound may be at least one selected from the group consisting of CO3O4, COSO4, CoOOH, Co(OOC(CH3))2, Co(OH)2, Co(NO3)2, COCO3, COCI2, and Col2. The first Co-containing compound may be preferably Co3O4. The Zr-containing compound may be at least one selected from the group consisting of ZrO2, Zr(OH)4, Zr(OC2H5)4, and Zr(OC3H7)4. The Zr-containing compound may be preferably ZrO2.

[0049] In a preferred embodiment, at least one of the first and second mixture may further comprise a Li source. The Li source may be LiOH or Li2CO3, and preferably LiOH.

[0050] In a preferred embodiment, the step of heating the first mixture may be performed at a temperature between about 600 °C and about 850 °C, preferably between about 650 °C and about 800 °C, for about 3 to about 10 hours, preferably for about 4 to about 9 hours. The step of heating the first mixture may be performed under an oxygen atmosphere.

[0051] In a preferred embodiment, the step of preparing the first positive electrode active material powder may further comprise: a.7 providing a third intermediate material obtained after the step of heating the first mixture; a.8 mixing the third intermediate material with a B-containing compound and / or a W-containing compound to obtain a third mixture; and a.9 heating the third mixture at a temperature between about 250 °C and about 500 °C, preferably between about 300 °C and about 450 °C, for about 5 to about 17 hours, preferably for about 7 to about 13 hours.

[0052] In a preferred embodiment, the B-containing compound may be at least one selected from the group consisting of boric acid (H3BO3), boron carbide (B4C), boron nitride (BN), and boron trifluoride (BF3). The B-containing compound may be preferably H3BO3. The W-containing compound may be at least one selected from the group consisting of tungsten trioxide (WO3), WC, and tungsten nitride (WN). The W-containing compound may be preferably WO3.

[0053] In a preferred embodiment, x4 may be about 85.0 at% or more, preferably about 87.0 at% or more, more preferably about 89.0 at% or more, stillmore preferably about 91.0 at% or more, relative to a total amount of M4, and x4 may be about 99.5 at% or less, preferably about 99.0 at% or less, relative to a total amount of M4. Specifically, the range of x4 may be: wherein about 85.0 at% < x4 < about 99.5 at%, preferably about 87.0 at% < x4 < about 99.0 at%, more preferably about 89.0 at% < x4 < about 99.0 at%, still more preferably about 91.0 at% < x4 < 99.0 at%, relative to a total amount of M4. Without wishing to be bound by any theory, if x4 is less than about 85.0 at%, relative to a total amount of M4, the capacity and the energy density may not be sufficient.

[0054] In a preferred embodiment, x4-x3 may be about 5.5 at% or more, preferably about 6.0 at% or more, more preferably about 6.5 at% or more, and x4- x3 may be about 20.0 at% or less, preferably about 15.0 at% or less, more preferably about 13.0 at% or less, still more preferably about 10.0 at% or less. Specifically, the range of x4-x3 may be: 5.5 at% < x4-x3 < 20.0 at%, preferably 6.0 at% < x4-x3 < 15.0 at%, more preferably 6.5 at% < x4-x3 < 13.0 at%, still more preferably 6.5 at% < x4-x3 < 10.0 at%. The blended positive electrode active material powder, with x4-x3 being 5.0 at% or more, may exhibit enhanced electrochemical performance, such as higher charge / discharge capacity, lower DCR growth after repeated charging / discharging cycles, and higher energy density, compared to a monolithic positive electrode active material powder with an almost single Ni content identical to the average Ni content of the blended positive electrode active material powder.Batery

[0055] The present disclosure further provides a battery comprising the blended positive electrode active material powder as described herein.Use of Batery

[0056] The present disclosure further provides a use of the present battery. For example, use in an electric or hybrid electric vehicle.

[0057] As appreciated by a person skilled in the art, all embodiments directed to the blended positive electrode active material powder as described herein may apply mutatis mutandis to the method for preparing the blended positive electrode active material powder, the battery comprising the blended positive electrode active material powder, and the use of the battery.EXPERIMENTAL ANALYSIS USED IN THE EXAMPLES AND THE COMPARATIVE EXAMPLES

[0058] The following analysis methods are used in the Example (EXs) and the Comparative Examples (CEXs).A) ICP-OES measurements

[0059] The amount of Li, Ni, Mn, Co, Al, and Zr in the positive electrode active material powder is measured with the ICP-OES method by using an Agilent ICP 720- ES (Agilent Technologies). 2 grams of powder sample is dissolved into 10 mL of high purity hydrochloric acid (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.

[0060] ICP-OES provides wt% of each element included in a material whose composition is determined by this technique. Conversion from wt% to at% 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 (or molecular weight) of the first element Ei, Ewti is wt% of an Ithelement Ei, Eawiis a standard atomic weight (molecular weight) of said ithelement E,, and n is an integer which represents the number of types of all elements included in the material.B) Particle size analysis

[0061] 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) Full cell testingC-l) Full cell preparation

[0062] 2000 mAh pouch-type cells are prepared as follows: the positive electrode active material powder, carbon Super-P (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 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 and 340 mm respectively for each side. Typical loading weight of a positive electrode active material is about 14.8±1 mg / cm2. The electrode is then dried and calendared to target electrode density of 3.3-3.4 g / cm3. In addition, an aluminum plate serving as a positive electrode current collector tab is arc-welded to an end portion of the positive electrode.

[0063] Commercially available negative electrodes are used. In short, a mixture of artificial graphite, carbon (Super P, Imerys), carboxy-methyl-cellulose- sodium, and styrene-butadiene-rubber, in a mass ratio of 95.0 / 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 ± 1 mg / cm2.

[0064] 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 carbonated (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.

[0065] 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 electrode assembly. 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 a flat pouch-type lithium secondary battery is prepared. The design capacity of the secondary battery is 2000 mAh when charged to 4.2 V. The full cell testing procedure uses a 1 C current definition of 2000 mA / g.C-2) Full cell performance test

[0066] The cells are charged and discharged under the following conditions for one cycle to determine the charge-discharge 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,- 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, the discharge is done at 1C rate in CC mode down to 2.7 V.

[0067] The discharge DCR. is measured at 1.5 C for 10 seconds at the beginning of every 100thcycle repetition and the end of the 700thcycle at 45°C. The DCR growth is calculated by the following formula :Discharge DCR at the 700 th cycle

[0068] The energy density of 2 Ah full cell in the 2.7 V to 4.2 V was obtained according to the below equation :EXAMPLES AND COMPARATIVE EXAMPLESThe present disclosure is further illustrated in the following examples.Positive electrode active material powder 1 (CAM1)

[0069] A positive electrode active material powder CAM1 was obtained through the following steps: a. 1stmixing step: Nio.98Mno.oiCoo.oi(OH)2powder was homogeneously mixed with LiOH and ZrO2to prepare a mixture, wherein the atomic ratio of Li to the total amount of Ni, Mn and Co was 1.04, and 0.125 at% of Zr was added, relative to the total amount of Ni, Mn, and Co. b. 1stheating step: the mixture obtained in step a. was heated at 800°C for 10.5 hours under oxygen atmosphere, followed by grinding and sieving.c. Milling step: the heated material obtained in step b. was bead milled with an aqueous solution, followed by filtering and drying. d. 2ndmixing step: the milled material obtained in step c. was mixed with CO(OH)2to prepare a mixture, and wherein Co was added in a content of 2.5 at%, relative to the total amount of Ni, Mn, and Co. e. 2ndheating step: the mixture obtained in step d. was heated at 750°C for 12.64 hours under oxygen atmosphere, followed by grinding and sieving process to obtain CAM1.Positive electrode active material powder 2 (CAM2)

[0070] A positive electrode active material powder CAM2 was obtained through the following steps: a. 1stmixing step: Nio.92Mn0.o3Coo.o5(OH)2powder was homogeneously mixed with LiOH and ZrO2to prepare a mixture, wherein the atomic ratio of Li to the total amount of Ni, Mn and Co was 1.04, and 0.125 at% of Zr was added, relative to the total amount of Ni, Mn, and Co. b. 1stheating step: the mixture obtained in step a. was heated at 835°C for 8 hours under oxygen atmosphere, followed by grinding and sieving. c. Milling step: the heated material obtained in step b. was bead milled with an aqueous solution, followed by filtering and drying. d. 2ndmixing step: the milled material obtained in step c. was mixed with CO(OH)2to prepare a mixture, wherein Co was added in a content of 3 at%, relative to the total amount of Ni, Mn, and Co. e. 2ndheating step: the mixture obtained in step d. was heated at 730°C for 9.53 hours under oxygen atmosphere followed by grinding and sieving process to obtain CAM2.Example 1 (EXI)

[0071] EXI was obtained by blending CAM1 and CAM2 homogeneously, wherein the weight ratio of CAM1 to CAM2 is 40:60.Comparative Example 1 (CEX1)

[0072] CEX1 was prepared as the same method as CAM1.Comparative Example 2 (CEX2)

[0073] CEX2 was prepared as the same method as CAM2.Comparative Example 3 (CEX3)

[0074] CEX3 was obtained through the following steps: a. 1stmixing step: Nio.94Mn0.o3Coo.o3(OH)2powder was homogeneously mixed with LiOH and ZrO2to prepare a mixture, wherein the atomic ratio of Li to the total amount of Ni, Mn and Co was 1.04, and 0.125 at% of Zr was added, relative to the total amount of Ni, Mn, and Co. b. 1stheating step: the mixture obtained in step a. was heated at 820°C for 10 hours under oxygen atmosphere, followed by grinding and sieving. c. Milling step: the heated material obtained in step b. was bead milled with an aqueous solution, followed by filtering and drying. d. 2ndmixing step: the heated material obtained in step c. was mixed with CO(OH)2to prepare a mixture, wherein 2.5 at% of Co was added, relative to the total amount of Ni, Mn, and Co. e. 2ndheating step: the mixture obtained in step d. was heated at 730°C for 12.5 hours under oxygen atmosphere, followed by grinding and sieving process to obtain CEX3.Comparative Example 4 (CEX4)

[0075] CEX4 was obtained by blending CAM1 and CAM2 homogeneously, wherein the weight ratio of CAM1 to CAM2 is 50:50.Comparative Example 5 (CEX5)

[0076] CEX5 was obtained by blending CAM1 and CAM2 homogeneously, wherein the weight ratio of CAM1 to CAM2 is 30:70.

[0077] Table 1 shows the metal compositions of CEX1, CEX2, and CEX3, measured by ICP-OES.Table 1. Summary of ICP-OES result of CEX1, CEX2, and CEX3* The atomic contents analyzed by ICP-OES are relative to the total amount of the metals other than Li.**Li / Me is the atomic ratio of Li to the sum of the metals other than Li, and the metals other than Li is indicated as Me.It should be noted that the Ni content of CEX3 is comparable to the average Ni contents of EXI, which is 91.50 at%.

[0078] CEX1 and CEX2 had monolithic morphology, and D50s of CEX1 and CEX2 were 3.92 pm and 3.13 pm, respectively.

[0079] Table 2 shows the electrochemical properties of EXI, CEX1 to CEX4, and CEX5, obtained by full cell test.Table 2. Summary of ICP-OES result of EXI, CEX1 to CEX4, and CEX5*CQ1 is the charge capacity at the first cycle.**DQ1 is the discharge capacity at the first cycle.***Retention Capacity is calculated by the following formula: 100 ,where DQ700 is the discharge capacity at the 700thcycle.

[0080] EXI, which was the mixture of two monolithic positive electrode active material powders with a Ni content difference of more than 5.0 at%, had higher CQ1, higher DQ1, higher retention capacity, higher energy density, and lower DCR growth compared to CEX3, which was a monolithic positive electrode active material powder with a single Ni content comparable to EXI.

[0081] CEX1 had a Ni content as high as 95.30 at%, and exhibited higher CQ1 and DQ1, compared to CEX2 having a Ni content of 88.97 at%. However, CQ1 andDQ1 of EXI were unexpectedly higher than those of CEX4, where the content of CEX1 in CEX4 was higher than the content of CEX1 in EXI. Furthermore, CQ1 and DQ1 of EXI were higher than those of CEX5. Thus, the maximal electrochemical performance was unexpectedly achieved in EXI where the weight ratio of CEX1 :CEX2 was 40:60.

[0082] In addition, although CEX1 exhibited higher CQ1 and DQ1, compared to CEX2, the retention capacity of CEX1 was much lower than that of CEX2, and the DCR growth of CEX1 was much higher than that of CEX2. Accordingly, a monolithic positive electrode active material powder solely comprising CEX1 is not preferable with respect to retention capacity and DCR. growth.

Claims

CLAIMS

1. A blended positive electrode active material powder for Li-ion rechargeable batteries, comprising a first positive electrode active material powder and a second positive electrode active material powder, wherein the first positive electrode active material powder consists of first particles comprising Li, Ml, and 0, wherein Ml comprises Ni in a content xl in at%, relative to a total amount of Ml; wherein Ml consists of:Ni, wherein 70.0 at% < xl < 95.0 at%, relative to a total amount of Ml;Mn in a content yl, wherein 1.0 at% < yl < 10.0 at%, relative to a total amount of Ml;Co in a content zl, wherein 4.0 at% < zl < 15.0 at%, relative to a total amount of Ml; andDI in a content dl, wherein 0.00 at% < dl < 5.0 at%, relative to a total amount of Ml, wherein Dl is at least one element other than Li, Ml, and O, wherein yl, zl, and dl are measured by ICP-OES, and wherein xl+yl+zl+dl is 100.0 at%;wherein the second positive electrode active material powder consists of second particles comprising Li, M2, and O, wherein M2 comprises Ni in a content x2 in at%, relative to a total amount of M2; wherein M2 consists of:Ni, wherein 75.0 at% < x2 < 100.0 at%, relative to a total amount of M2;Mn in a content y2, wherein 0.0 at% < y2 < 8.0 at%, relative to a total amount of M2;Co in a content z2, wherein 0.0 at% < z2 < 13.0 at%, relative to a total amount of M2; andD2 in a content d2, wherein 0.0 at% < d2 < 4.0 at%, relative to a total amount of M2, wherein D2 is at least one element other than Li, M2, and O, wherein y2, z2, and d2 are measured by ICP-OES, and wherein x2+y2+z2+d2 is 100.0 at%; wherein xl and x2 are measured by ICP-OES, wherein x2-xl > 5.0 at%,wherein each of the first particles consists of at least one primary particle (PPI) and at most twenty primary particles (PPI), determined by SEM image analysis; wherein each of the second particles consists of at least one primary particle (PP2) and at most twenty primary particles (PP2), determined by SEM image analysis; and wherein a content of the first particles in wt%, relative to a total weight of the first and second particles, ranges from 55 wt% to 65 wt%.

2. The blended positive electrode active material powder according to claim 1, wherein DI is at least one element selected from the group consisting of Al, Zr, B, W, Sr, Sb, Ti, Ba, Ca, Cr, F, Fe, Mg, Mo, Si, Y, V, Zn, and S.

3. The blended positive electrode active material powder according to claim 1, wherein D2 is at least one element selected from the group consisting of Al, Zr, B, W, Sr, Sb, Ti, Ba, Ca, Cr, F, Fe, Mg, Mo, Si, Y, V, Zn, and S.

4. The blended positive electrode active material powder according to any one of the preceding claims, wherein 80.0 at% < xl < 94.0 at%, preferably 82.0 at% < xl < 93.0 at%, more preferably 84.0 at% < xl < 92.0 at%, still more preferably 85.0 at% < xl < 91.0 at%, relative to a total amount of Ml.

5. The blended positive electrode active material powder according to any one of the preceding claims, wherein 85.0 at% < x2 < 100.0 at%, preferably 88.0 at% < x2 < 99.0 at%, more preferably 90.0 at% < x2 < 98.0 at%, still more preferably 92.0 at% < x2 < 97.0 at%, relative to a total amount of M2.

6. The blended positive electrode active material powder according to any one of the preceding claims, wherein 5.5 at% < x2-xl < 20.0 at%, preferably 6.0 at% < x2-xl < 15.0 at%, more preferably 6.5 at% < x2-xl < 13.0 at%, still more preferably 6.5 at% < x2-xl < 10.0 at%.

7. The blended positive electrode active material powder according to any one of the preceding claims, wherein D50 of the first particles ranges from 1.0 pm to 8.0 pm, preferably from 1.5 pm to 7.5 pm, more preferably from 2.0 pm to 7.0 pm, still more preferably from 2.5 pm to 6.5 pm, measured by laser diffraction

8. The blended positive electrode active material powder according to any one of the preceding claims, wherein D50 of the second particles is equal to or larger than D50 of the first particles, measured by laser diffraction

9. A method for preparing a blended positive electrode active material powder for Li-ion rechargeable batteries, preferably the blended positive electrode active material powder according to any one of the preceding claims, comprising: a. preparing a first positive electrode active material powder, b. preparing a second positive electrode active material powder, and c. mixing the first and second positive electrode active material powders to obtain the blended positive electrode active material powder, wherein the step of preparing the first positive electrode active material powder comprises: a.l providing a first starting material comprising a Li source and a first transition metal composite precursor comprising M3, wherein M3 comprises Ni in a content x3 in at%, relative to a total amount of M3; a.2 heating the first starting material at a temperature between 600 °C and 1000 °C to obtain a first heated material; a.3 providing a first intermediate material comprising the first heated material; a.4 milling the first intermediate material to obtain a first milled material; a.5 providing a first mixture comprising the first milled material; and a.6 heating the first mixture at a temperature between 500 °C and 900 °C, wherein the step of preparing the second positive electrode active material powder comprises: b.l providing a second starting material comprising a Li source and a second transition metal composite precursor comprising M4, wherein M4 comprises Ni in a content x4 in at%, relative to a total amount of M4; b.2 heating the second starting material at a temperature between 600 °C and 1000 °C to obtain a second heated material; b.3 providing a second intermediate material comprising the second heated material; b.4 milling the second intermediate material to obtain a second milled material; b.5 providing a second mixture comprising the second milled material; and b.6 heating the second mixture at a temperature between 500 °C and 900 °C, wherein x4-x3 > 5.0 at%, andwherein a content of the first positive electrode active material powder in wt%, relative to a total weight of the blended positive electrode active material powder, ranges from 55 wt% to 65 wt%.

10. The method according to claim 9, wherein at least one of the first and second intermediate material further comprises a solution comprising a Cocontaining compound.

11. The method according to claim 9 or 10, wherein at least one of the first and second mixture further comprises at least one compound comprising at least one element selected from the group consisting of Co, Al, Zr, Ti, W, Sr, B, Ba, Ca, Cr, F, Fe, Sb, Si, Y, V, and Zn, preferably at least one of Co, Al,Zr, B, W and Ti.

12. A battery comprising the blended positive electrode active material powder according to any one of claims 1 to 9.

13. Use of the battery according to claim 12 in an electric vehicle or in a hybrid electric vehicle.

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