Sodium nickel-manganese-iron oxide as cathode active material for sodium batteries

Abstract

The present disclosure relates to a cathode active material for sodium batteries, comprising sodium (Na), M, and oxygen (O), wherein M includes nickel (Ni), manganese (Mn), and iron (Fe), and / or zinc (Zn) and titanium (Ti). Moreover, the cathode active material further comprises silicium (Si) on the surface of the particles. The cathode active material according to this disclosure might have improved moisture stability. The present disclosure also relates to a method for manufacturing said cathode active material; and to a battery comprising said cathode active material, for an electric vehicle or hybrid electric vehicle.

Description

SODIUM NICKEL-MANGANESE-IRON OXIDE AS CATHODE ACTIVE MATERIAL FORSODIUM BATTERIESTECHNICAL FIELD

[0001] The present disclosure relates to a cathode active material for sodium batteries, comprising sodium (Na), M, and oxygen (O), wherein M includes nickel (Ni), manganese (Mn), and iron (Fe), and / or zinc (Zn) and titanium (Ti). Moreover, the cathode active material further comprises silicium (Si) on the surface of the particles. The cathode active material according to this disclosure might have improved moisture stability. The present disclosure also relates to a method for manufacturing said cathode active material; and to a battery comprising said cathode active material, for an electric vehicle or hybrid electric vehicle.BACKGROUND ART

[0002] Modern batteries require high energy density as well as long cycle life, especially for automotive applications. Currently, lithium-based oxides are the most promising cathode active materials used in batteries for electric vehicles or hybrid electric vehicles. However, due to the high demand and uneven distribution of lithium sources, there is a need for an alternative to lithium-based cathode active materials.

[0003] Sodium ion batteries are an emerging technology offering a more sustainable alternative to traditional Li-ion batteries. Sodium (Na) is an abundant and inexpensive element well distributed around the world. Also, sodium-ion batteries can operate efficiently at a wider range of temperatures and have a lower environmental impact due to the absence of cobalt and other scarce materials.

[0004] Currently, NFM materials (nickel-iron-manganese-based oxides, such as NaFeo.5Mno.5O2) and NMZT materials (nickel-manganese-zinc-titanium-based oxides) are the most promising cathode active materials for sodium batteries. They present a layered structure and provide high specific capacity. However, NFM and NMZT materials present poor stability since they are hygroscopic and tend to react with the water from the air (moisture) forming salts such as sodium carbonate and / or sodium hydroxide. The presence of hydroxide or carbonate salts is related to gas generation in the cells (bulging), resulting in poor cycling performance and raising safety issues.

[0005] Coating a cathode active material creates a physical barrier preventing a direct contact between the cathode active material and the electrolyte of a battery, protecting the surface of the cathode active material and improving its stability and lifetime, see Nisar et al, Energy Storage Mater. 38, 2021, 309-328.

[0006] Organosilanes, such as tetraethoxysilane, octadecyltrimethoxysilane, hexadecyl trimethoxysilane, decyltrimethoxysilane and hexyltrimethoxysilane, have been investigated as potential coating agents to improve the cyclic stability of lithium-based cathode active materials, see US2022158186A1.

[0007] CN116936809A1 discloses Na-Cu-Fe-Mn-based oxide powders as cathode active materials, further comprising octadecyltri methoxysilane on the surface of the powder particles The octadecyltrimethoxysilane improves the hydrophobic properties and reduces its hygroscopicity.

[0008] Particles properties, such as particle size distribution (PSD) or crystalline size have an impact on the performance of a cathode active material. In particular, the battery performance is improved when a cathode active material has a narrow particle size distribution (i.e. narrow D50).

[0009] CN117613229A1 discloses a cathode active material powder for sodium batteries, according to the formula NaNi0.28Fe0.33Mn0.34AI0.05 further comprising methyltrimethoxysilane, wherein the cathode active material comprises particles with a size between 15-30 nm. The resulting cathode active material shows improved air stability.

[0010] CN115939344 discloses a method for the preparation of NFM materials coated with organosilanes. The method comprises the step of mixing an aqueous solution containing the organosilane, with the NFM material under acidic conditions (pH 3.5). However, it is known that the NMF material can adversely react with the aqueous solution modifying its structure and removing Na-ion centers from the layered structure, changing the Ni-binding phase, and generating byproducts such as sodium carbonate which reduces the cyclic stability of the cathode active material.

[0011] Therefore, there is a need for sodium-based cathode active materials with improved stability.

[0012] Additionally, there is a need for a method for manufacturing the above-mentioned cathode active material with high throughput.SUMMARY

[0013] The present disclosure provides a cathode active material for sodium batteries, comprising Na, M, and O, wherein M comprises:Ni in an atomic content x, wherein 0.10 < x < 0.60 relative to M,Fe in an atomic content y, wherein 0.0 < y < 0.60 relative to M, Mn in an atomic content z, wherein 0.10 < z < 0.60 relative to M, Zn in an atomic content q, wherein 0.0 < q < 0.10 relative to M,- Ti in an atomic content f, wherein 0.0 < f < 0.20 relative to M,Si in an atomic content a, wherein 0.0001 < a < 0.005 relative to M, wherein x, y, z, q, f and a are determined by ICP-OES, x+y+z+q+f+a is 1, the Na / M atomic ratio is between 0.8 to 1.5, and the Sixps / Siicp ratio is higher than 1, wherein Sixps is the molar fraction of Si as determined by XPS analysis, and Siicp is the molar fraction of Si as determined by ICP-OES analysis, and wherein the cathode active material comprises particles with a median particle size D50 equal to or lower than 20 pm.

[0014] It has been found that a cathode active material according to this disclosure has improved air and / or moisture stability. Moreover, the cathode active material according to this disclosure comprises a low carbon content which may improve its battery performance.

[0015] The present disclosure also provides a method for manufacturing said cathode active material, comprising the following steps:1) mixing a metal-based precursor with a sodium source to obtain a first mixture;2) heating the first mixture at a temperature between 700 °C and 1100 °C, to obtain a first heated material;3) crushing and sieving the first heated material to obtain a crushed and sieved material with a median particle size D50 equal to or lower than 20 pm;4) mixing the crushed and sieved material with a Si source to obtain a second mixture;5) drying the second mixture at a temperature between 40 °C and 80 °C, to obtain a dried second mixture; and6) heating the dried second mixture at a temperature between 50 °C and 500 °C, to obtain the cathode active material.

[0016] The present disclosure also provides a battery comprising said cathode active material.

[0017] 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.DETAILED DESCRIPTION

[0018] In the following detailed description, preferred embodiments are described in detail to enable the practice of the present invention. Although the present invention is described with reference to these specific embodiments, it will be understood that the present invention is not limited to these preferred embodiments. In contrast, the present invention includes numerous alternatives, modifications and equivalents as will become apparent from consideration of the following detailed description.

[0019] The following terms are intended to have the meaning presented below and are useful in understanding the description and intended scope of this disclosure.

[0020] The term "comprising", as used herein and in the claims, should not be interpreted as being restricted to the means listed thereafter; it does not exclude other elements or steps. It needs to be interpreted as specifying the presence of the stated features, integers, steps, or components as referred to, but does not preclude the presence or addition of one or more other features, integers, steps or components, or groups thereof. Thus, the scope of the expression "a composition comprising components A and B" should not be limited to compositions consisting only of components A and B. It means that with respect to the present disclosure, the only relevant components of the composition are A and B. Accordingly, the terms "comprising" and "including" encompass the more restrictive terms "consisting essentially of" and "consisting of".

[0021] The term "cathode active material" (also known as CAM or positive electrode active material) refers to a material which is electrochemically active in a positive electrode or cathode. By active material, it must be understood to be capable of capturing and releasing Na ions when subjected to a voltage change over a predetermined period.

[0022] In the framework of the present disclosure, the content of a particular element of the periodic table signifies atomic percentage. The at% or "atomic percent" of a given element expression of a concentration means how many percent of all atoms in the concerned compound are atoms of said element. The designation at% is equivalent to mol% or "molar percent".

[0023] The term "median particle size D50", as defined herein, can be interchangeably used with the terms "D50" or "d50" or "median particle size" or "a median particle size (d50 or D50)". D50 is defined as the particle size at 50% of the cumulative volume% distributions. D50 is typically determined by laser diffraction particle size analysis. D10 and D90 are defined as particle sizes at 10% and 90% of cumulative volume% distribution when measured by laser scattering method as described in this specification, respectively.

[0024] The term "XXPS" refers to the content of element X as determined by XPS analysis, wherein X is an element of the periodic table. For example, "Sixps" refers to Si content as determined by XPS analysis.

[0025] The term "XICP" refers to the content of the element as determined by ICP-OES, wherein X is an element of the periodic table. For example, "Siicp" refers to Si content as determined by ICP-OES.

[0026] As used herein, a range of values "between X and Y" include the endpoints of X and Y.

[0027] The term "about" refers 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.

[0028] The term "organosilanes" refers to a class of chemical compounds containing at least one carbon-to-silicon bond. Examples of organosilanes are trimethoxymethylsilane, 1, 1,3,3- tetramethyldisiloxane, and polymethylhydrosiloxane.Cathode Active Material

[0029] In a first aspect, the present disclosure relates to a cathode active material for sodium batteries, wherein the cathode active material comprises Na, M, and O, wherein M comprises: Ni in an atomic content x, wherein 0.10 < x < 0.60 relative to M, Fe in an atomic content y, wherein 0.0 < y < 0.60 relative to M, Mn in an atomic content z, wherein 0.10 < z < 0.60 relative to M, Zn in an atomic content q, wherein 0.0 < q < 0.10 relative to M,- Ti in an atomic content f, wherein 0.0 < f < 0.20 relative to M,Si in an atomic content a, wherein 0.0001 < a < 0.005 relative to M, wherein x, y, z, q, f and a are determined by ICP-OES, x+y+z+q+f+a is 1, the Na / M atomic ratio is between 0.8 to 1.5, and the Sixps / Siicp ratio is higher than 1, wherein Sixps is the molar fraction of Si as determined by XPS analysis, and Siicp is the molar fraction of Si as determined by ICP-OES analysis, and wherein the cathode active material comprises particles with a median particle size D50 equal to or lower than 20 pm.

[0030] In one embodiment, the cathode active material comprises Ni in an atomic content x, wherein 0.15 < x < 0.50 relative to M. In another embodiment, 0.20 < x < 0.40 relative to M. In another embodiment, 0.28 < x < 0.38 relative to M. For example, x is 0.28, 0.29, 0.30, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37 or 0.38, relative to M.

[0031] In one embodiment, the cathode active material comprises Fe in an atomic content y, wherein 0.10 < y < 0.50 relative to M. In another embodiment, 0.15 < y < 0.50 relative to M. In another embodiment, 0.20 < y < 0.40 relative to M. In another embodiment, 0.28 < y < 0.38 relative to M. For example, y is 0.28, 0.29, 0.30, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37 or 0.38, relative to M. In another embodiment, y is 0 relative to M.

[0032] In one embodiment, the cathode active material comprises Mn in an atomic content z, wherein 0.15 < z < 0.50 relative to M. In another embodiment, 0.20 < z < 0.40 relative to M. In another embodiment, 0.28 < z < 0.38 relative to M. For example, z is 0.28, 0.29, 0.30, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37 or 0.38, relative to M.

[0033] In one embodiment, the cathode active material comprises Zn in an atomic content q, wherein 0.01 < q < 0.07 relative to M. In another embodiment, 0.01 < q < 0.05 relative to M. In another embodiment, 0.02 < q < 0.05 relative to M. For example, q is 0.02, 0.03, 0.04 or 0.05 relative to M. In another embodiment, q is 0 relative to M.

[0034] In one embodiment, the cathode active material comprises Ti in an atomic content f, wherein 0.01 < f < 0.17 relative to M. In another embodiment, 0.05 < f < 0.14 relative to M. In another embodiment, 0.07 < f < 0.13 relative to M. For example, f is 0.07, 0.08, 0.09, 0.10, 0.11, 0.12 or 0.13 relative to M. In another embodiment, f is 0 relative to M.

[0035] In one embodiment, the cathode active material comprises Si in an atomic content a, wherein 0.0005 < a < 0.003 relative to M. In another embodiment, 0.0005 < a < 0.0015 relative to M. In another embodiment, 0.0007 < a < 0.0015 relative to M. For example, a is 0.0007, 0.0008, 0.0009, 0.001, 0.0011, 0.0012, 0.0013, 0.0014 or 0.0015, relative to M.

[0036] In one embodiment of the cathode active material, the Na / M atomic ratio is between 0.8 and 1.2. In another embodiment, the Na / M atomic ratio is between 0.8 and 1.1. For example, the Na / M atomic ratio is 0.80, 0.85, 0.90, 0.96, 0.97, 0.98, 0.99, 1.00, 1.01, 1.02, 1.03, 1.04, 1.05, 1.06, 1.07, 1.08, 1.09 or 1.10.

[0037] In one embodiment, the cathode active material comprises Ni in an atomic content x, wherein 0.20 < x < 0.40 relative to M; Fe in an atomic content y, wherein 0.20 < y < 0.40relative to M; Mn in an atomic content z, wherein 0.20 < z < 0.40 relative to M; Zn in an atomic content q, wherein q is 0 relative to M; Ti in an atomic content f, wherein f is 0 relative to M; Si in an atomic content a, wherein 0.0007 < a < 0.0015 relative to M; the Na / M atomic ratio is between 0.9 and 1.2, a Sixps / Siicp ratio higher than 100, and wherein the cathode active material comprises particles with a median particle size D50 equal to or lower than 10 pm.

[0038] In one embodiment, the cathode active material comprises Ni in an atomic content x, wherein 0.15 < x < 0.50 relative to M; Fe in an atomic content y, wherein 0.15 < y < 0.50 relative to M; Mn in an atomic content z, wherein 0.15 < z < 0.50 relative to M; Zn in an atomic content q, wherein q is 0 relative to M; Ti in an atomic content f, wherein f is 0 relative to M; Si in an atomic content a, wherein 0.0005 < a < 0.003 relative to M; the Na / M atomic ratio is between 0.9 and 1.2, the Sixps / Siicp ratio is higher than 100, and wherein the cathode active material comprises particles with a median particle size D50 equal to or lower than 5 pm.

[0039] In one embodiment, the cathode active material comprises Ni in an atomic content x, wherein 0.15 < x < 0.50 relative to M; Fe in an atomic content y, wherein y is 0 relative to M; Mn in an atomic content z, wherein 0.15 < z < 0.50 relative to M; Zn in an atomic content q, wherein 0.01 < q < 0.07 relative to M; Ti in an atomic content f, wherein 0.01 < f < 0.17 relative to M; Si in an atomic content a, wherein 0.0005 < a < 0.003 relative to M; the Na / M atomic ratio is between 0.8 and 1.0, the Sixps / Siicp ratio is higher than 100, and wherein the cathode active material comprises particles with a median particle size D50 equal to or lower than 5 pm.

[0040] In one embodiment, the cathode active material is according to the formula (I) NawNixiFeyiMnziZnqiTifiSiaiO2, wherein 0.80 < w < 1.50; 0.10 < xl < 0.60; 0.0 < yl < 0.60; 0.10 < zl < 0.60; 0.0 < ql < 0.10; 0.0 < fl < 0.20; 0.0001 < al < 0.005; wherein xl, yl, zl, ql, fl and al are determined by ICP-OES, and xl+yl+zl+ql+fl+al is 1, the Sixps / Siicp ratio is higher than 1, wherein Sixps is the molar fraction of Si as determined by XPS analysis, and Siicp is the molar fraction of Si as determined by ICP-OES analysis, and wherein the cathode active material comprises particles with a median particle size D50 equal to or lower than 20 pm.

[0041] In one embodiment, the cathode active material is according to the formula (I), wherein 0.15 < xl < 0.50. In another embodiment, 0.20 < xl < 0.40. In another embodiment, 0.28 < xl < 0.38. For example, xl is 0.28, 0.29, 0.30, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37 or 0.38.

[0042] In one embodiment, the cathode active material is according to the formula (I), wherein 0.15 < yl < 0.50. In another embodiment, 0.20 < yl < 0.40. In another embodiment, 0.28 < yl < 0.38. For example, yl is 0.28, 0.29, 0.30, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37 or 0.38. In another embodiment, yl is 0.

[0043] In one embodiment, the cathode active material is according to the formula (I), wherein 0.15 < zl < 0.50. In another embodiment, 0.20 < zl < 0.40. In another embodiment, 0.28 < zl < 0.38. For example, zl is 0.28, 0.29, 0.30, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37 or 0.38.

[0044] In one embodiment, the cathode active material is according to the formula (I), wherein 0.01 < ql < 0.07. In another embodiment, 0.01 < ql < 0.05. In another embodiment, 0.02 < ql < 0.05. For example, ql is 0.02, 0.03, 0.04 or 0.05. In another embodiment, ql is 0.

[0045] In one embodiment, the cathode active material is according to the formula (I), wherein 0.01 < fl < 0.17. In another embodiment, 0.05 < fl < 0.14. In another embodiment, 0.07 < fl < 0.13. For example, fl is 0.07, 0.08, 0.09, 0.10, 0.11, 0.12 or 0.13. In another embodiment, fl is 0.

[0046] In one embodiment, the cathode active material is according to the formula (I), wherein 0.0005 < al < 0.003. In another embodiment, 0.0005 < al < 0.0015. In another embodiment, 0.0007 < al < 0.0015. For example, al is 0.0007, 0.0008, 0.0009, 0.001, 0.0011, 0.0012, 0.0013, 0.0014 or 0.0015.

[0047] In one embodiment, the cathode active material is according to the formula (I), wherein 0.8 < w < 1.2. In another embodiment, 0.8 < w < 1.1. For example, w is 0.80, 0.85, 0.90, 0.95, 0.96, 0.97, 0.98, 0.99, 1.00, 1.01, 1.02, 1.03, 1.04, 1.05, 1.06, 1.07, 1.08, 1.09 or 1.10.

[0048] In one embodiment, the cathode active material is according to the formula (I), wherein 0.95 < w < 1.2; 0.15 < xl < 0.50; 0.15 < yl < 0.50; 0.15 < zl < 0.50; ql is 0; fl is 0; 0.0005 < al < 0.003, wherein xl, yl, zl, ql, fl and al are determined by ICP-OES, and xl+yl+zl+ql+fl+al is 1, the Sixps / Siicp ratio is higher than 1, and wherein the cathode active material comprises particles with a median particle size D50 equal to or lower than 20 pm.

[0049] In one embodiment, the cathode active material is according to the formula (I), wherein 0.9 < w < 1.1; 0.20 < xl < 0.40; 0.20 < yl < 0.40; 0.20 < zl < 0.40; ql is 0; fl is 0; 0.0005 < al < 0.0015, wherein xl, yl, zl, ql, fl and al are determined by ICP-OES, and xl+yl+zl+ql+fl+al is 1, the Sixps / Siicp ratio is higher than 50, and wherein the cathode active material comprises particles with a median particle size D50 equal to or lower than 10 pm.

[0050] In one embodiment, the cathode active material is according to the formula (I), wherein 0.80 < w < 1.0; 0.15 < xl < 0.50; yl is 0; 0.15 < zl < 0.50; 0.01 < ql < 0.07; 0.01 < fl < 0.17; 0.0005 < al < 0.0015, wherein xl, yl, zl, ql, fl and al are determined by ICP-OES, and xl+yl+zl+ql+fl+al is 1, the Sixps / Siicp ratio is higher than 50, and wherein the cathode active material comprises particles with a median particle size D50 equal to or lower than 10 pm.

[0051] In one embodiment, the cathode active material is according to the formula (I), wherein w is 0.85; xl is 0.38; yl is 0; zl is 0.48; ql is 0.04; fl is 0.10; and 0.0005 < al < 0.0015, wherein xl, yl, zl, ql, fl and al are determined by ICP-OES, and xl+yl+zl+ql+fl+al is 1, the Sixps / Siicp ratio is higher than 50, and wherein the cathode active material comprises particles with a median particle size D50 equal to or lower than 10 pm.

[0052] In one embodiment, the cathode active material comprises Si in a content Sixps and Siicp, wherein the Sixps / Siicp ratio is equal to or higher than 5. In another embodiment, the Sixps / Siicp ratio is equal to or higher than 10. In another embodiment, the Sixps / Siicp ratio is equal to or higher than 50. In another embodiment, the Sixps / Siicp ratio is equal to or higher than 100. In another embodiment, the Sixps / Siicp ratio is equal to or higher than 500. In another embodiment, the Sixps / Siicp ratio is equal to or higher than 700. For example, the Sixps / Siicp ratio is 710, 720, 729, 750, 780, 800, 820, 850, 880, 900, 927, 950, 980, or 1000.

[0053] In one embodiment, the cathode active material comprises particles with a median particle size D50 between 2.0 pm and 15.0 pm. In another embodiment, the median particle size D50 is equal to or lower than 10 pm. In another embodiment, the median particle size D50 is between 3.0 pm and 12.0 pm. For example, median particle size D50 is 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5, 10.0, 10.5, 11.0, 11.5 or 12.0 pm. In another embodiment, the median particle size D50 is equal to or lower than 5 pm.

[0054] In one embodiment, the cathode active material is according to the formula (I), wherein 0.9 < w < 1.2; 0.20 < xl < 0.40; 0.20 < yl < 0.40; 0.20 < zl < 0.40, 0.0007 < al< 0.0015, wherein xl, yl, zl and al are determined by ICP-OES, and xl+yl+zl+al is 1, the Sixps / Siicp ratio is equal to or higher than 100, and wherein the cathode active material comprises particles with a median particle size D50 equal to or lower than 10 pm.Method for manufacturing a cathode active material

[0055] In a second aspect, the present disclosure relates to a method for manufacturing the cathode active material according to the first aspect, wherein the method comprises the following steps:1) mixing a metal-based precursor with a sodium source to obtain a first mixture;2) heating the first mixture at a temperature between 700 °C and 1100 °C, to obtain a first heated material;3) crushing and sieving the first heated material to obtain a crushed and sieved material with a median particle size D50 equal to or lower than 20 pm;4) mixing the crushed and sieved material with a Si source to obtain a second mixture;5) drying the second mixture at a temperature between 40 °C and 80 °C, to obtain a dried second mixture; and6) heating the dried second mixture at a temperature between 50 °C and 500 °C, to obtain the cathode active material.

[0056] The cathode active material according to the first aspect of the present disclosure may be obtained by a method according to the second aspect of the present disclosure. In detail, the technical features of the first aspect of the present disclosure, e.g., the specific composition of the cathode active material, specific surface area, median particle size, carbon content, discharge capacity, may be achieved by the method according to the second aspect of the present disclosure.

[0057] In one embodiment of the method, the metal-based precursor comprises Ni, Fe, and Mn. In another embodiment, the metal-based precursor is according to the formula (II) Nix2Fey2Mnz2ZnqiTifi(OH)2, wherein 0.10 < x2 < 0.60; 0. 0 < y2 < 0.60; 0.10 < z2 < 0.60; 0.0 < q2 < 0.10; 0.0 < f2 < 0.20; wherein x2, y2, z2, q2 and f2 are determined by ICP-OES, and x2+y2+z2+q2+f2 is 1.

[0058] In one embodiment of the method, the metal-based precursor is according to formula (II), wherein 0.15 < x2 < 0.50. In another embodiment, 0.20 < x2 < 0.40. In another embodiment, 0.28 < x2 < 0.38. For example, x2 is 0.28, 0.29, 0.30, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37 or 0.38.

[0059] In one embodiment of the method, the metal-based precursor is according to formula (II), wherein 0.15 < y2 < 0.50. In another embodiment, 0.20 < y2 < 0.40. In another embodiment, 0.28 < y2 < 0.38. For example, y2 is 0.28, 0.29, 0.30, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37 or 0.38. In another embodiment, y2 is 0.

[0060] In one embodiment of the method, the metal-based precursor is according to formula (II), wherein 0.15 < z2 < 0.50. In another embodiment, 0.20 < z2 < 0.40. In another embodiment, 0.28 < z2 < 0.38. For example, z2 is 0.28, 0.29, 0.30, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37 or 0.38.

[0061] In one embodiment of the method, the metal-based precursor is according to formula (II), wherein 0.01 < q2 < 0.07. In another embodiment, 0.01 < q2 < 0.05. In another embodiment, 0.02 < q2 < 0.05. For example, q2 is 0.02, 0.03, 0.04 or 0.05. In another embodiment, q2 is 0.

[0062] In one embodiment of the method, the metal-based precursor is according to formula(II), wherein 0.01 < f2 < 0.17. In another embodiment, 0.05 < f2 < 0.14. In another embodiment, 0.07 < f2 < 0.13. For example, f2 is 0.07, 0.08, 0.09, 0.10, 0.11, 0.12 or 0.13. In another embodiment, f2 is 0.

[0063] In one embodiment of the method, the metal-based precursor is according to formula (II), wherein 0.15 < x2 < 0.50; 0.15 < y2 < 0.50; 0.15 < z2 < 0.50; q2 is 0; f2 is 0, wherein x2, y2, z2, q2, f2 are measured by ICP-OES, and x2+y2+z2+q2+f2 is 1. In another embodiment, 0.20 < x2 < 0.40; 0.20 < y2 < 0.40; 0.20 < z2 < 0.40; q2 is 0; f2 is 0.

[0064] In one embodiment of the method, the metal-based precursor is according to formula (II), 0.20 < x2 < 0.40; 0.20 < y2 < 0.40; 0.20 < z2 < 0.40; q2 is 0; f2 is 0; wherein x2, y2, z2, q2, f2 are determined by ICP-OES, and x2+y2+z2+q2+f2 is 1.

[0065] In one embodiment of the method, the metal-based precursor is according to formula (II), 0.15 < x2 < 0.50; y2 is 0; 0.15 < z2 < 0.50; 0.01 < q2 < 0.07; 0.01 < f2 < 0.14; wherein x2, y2, z2, q2, f2 are determined by ICP-OES, and x2+y2+z2+q2+f2 is 1.

[0066] In one embodiment of the method, the lithium source is NaOH, Na?CO3 or a mixture thereof.

[0067] In one embodiment of the method, the first mixture has a Na / (Ni, Fe, Mn) ratio of about 1.

[0068] In one embodiment of the method, the first mixture is heated at a temperature between 800 °C and 1000 °C. For example, at 800 °C, 850 °C, 900 °C, 950 °C or 1000 °C.

[0069] In one embodiment of the method, the first mixture is heated at about 900 °C for a period of time between 8 to 14 hours. For example, the first mixture is heated at 900 °C for 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours or 14 hours.

[0070] In one embodiment of the method, the first heated material is crushed and sieved to obtain a material having a median particle size D50 equal to or lower than 10 pm. In another embodiment, the crushed and sieved material has a median particle size D50 equal to or lower than 5 pm. For example, the median particle size D50 is 4.5 pm.

[0071] In one embodiment of the method, the crushed and sieved material is mixed with a Si source in a non-aqueous solution, to obtain a second mixture.

[0072] In one embodiment of the method, the crushed and sieved material is mixed with an organosilane to obtain a second mixture. In another embodiment, the crushed and sieved material is mixed with from about 0.05 mol% to about 0.15 mol% of an organosilane, wherein the content of the organosilane is defined with respect to the molar contents of Ni, Fe and Mn. In another embodiment, the crushed and sieved material is mixed with from about 0.05 mol% to about 0.15 mol% of trimethoxymethylsilane, 1,1,3,3-tetramethyldisiloxane, or polymethylhydrosiloxane, wherein the content of the organosilane is defined with respect to the molar contents of Ni, Fe, Mn, Zn and Ti.

[0073] In another embodiment, the crushed and sieved material is mixed with about 0.05 mol% or 0.1 mol% of trimethoxymethylsilane with respect to the molar contents of Ni, Fe, Mn, Zn and Ti, to obtain a second mixture.

[0074] In one embodiment of the method, the second mixture is heated at 60 °C for a period of time between 4 and 10 hours, to obtain a dried second mixture. For example, for 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours or 10 hours.

[0075] In one embodiment of the method, the dried second mixture is heated at a temperature between 80 °C to 350 °C. In another embodiment, the dried second mixture is heated at a temperature between 150 °C to 350 °C. In another embodiment, the dried second mixture is heated at a temperature between 150 °C to 300 °C. In another embodiment, the dried second mixture is heated at 250 °C.

[0076] In one embodiment of the method, the dried second mixture is heated for a period of time between 4 and 10 hours, to obtain a cathode active material. In another embodiment, the dried second mixture is heated for 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours or 10 hours, to obtain a cathode active material. In another embodiment, the dried second mixture is heated at 250 °C, for 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours or 10 hours, to obtain a cathode active material.

[0077] In one embodiment, the method for manufacturing the cathode active material comprises the following steps:Mixing Nio.3Feo.3Mno.3(OH)2 with sodium carbonate to obtain a first mixture, wherein the first mixture has a Na / (Ni,Fe,Mn) ratio about 1.02, heating the first mixture at 900 °C for 12 hours under air atmosphere to obtain a first heated material,- crushing and sieving the first heated material to obtain a crushed and sieved material with a median particle size D50 equal to or lower than 10 pm, mixing the crushed and sieved material with about 0.1 mol% of trimethoxymethylsilane, relative to the molar contents of Ni, Fe and Mn, dissolved in ethanol (45 ml / kg liquid to solid ratio), to obtain a second mixture.- drying the second mixture at 60 °C for 6 hours to obtain a dried second mixture,- heating the dried second mixture at 250 °C for 6 hours to obtain a cathode active material.Product by Process

[0078] In a third aspect, the present disclosure relates to a cathode active material obtainable by a process according to the second aspect of this disclosure, wherein the cathode active material comprises Na, M', and O, wherein M' comprises:Ni in an atomic content x3, wherein 0.10 < x3 < 0.60 relative to M',Fe in an atomic content y3, wherein 0.0 < y3 < 0.60 relative to M', Mn in an atomic content z3, wherein 0.10 < z3 < 0.60 relative to M', Zn in an atomic content q3, wherein 0.0 < q3 < 0.10 relative to M',- Ti in an atomic content f3, wherein 0.0 < f3 < 0.20 relative to M',Si in an atomic content a3, wherein 0.0001 < a3 < 0.005 relative to M', wherein x3, y3, z3, q3, f3 and a are determined by ICP-OES, x3+y3+z3+q3+f3+a3 is 1, the Na / M' atomic ratio is between 0.8 to 1.5, and the Sixps / Siicp ratio is higher than 1, wherein Sixps is the molar fraction of Si as determined by XPS analysis, and Siicp is the molar fraction of Si as determined by ICP-OES analysis, and wherein the cathode active material comprises particles with a median particle size D50 equal to or lower than 20 pm.

[0079] In one embodiment, the cathode active material obtainable by a process according to the second aspect of this disclosure, comprises Ni in an atomic content x3, wherein 0.15 < x3 < 0.50 relative to M'. In another embodiment, 0.20 < x3 < 0.40 relative to M'. In another embodiment, 0.28 < x3 < 0.38 relative to M'. For example, x3 is 0.28, 0.29, 0.30, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37 or 0.38, relative to M'.

[0080] In one embodiment, the cathode active material obtainable by a process according to the second aspect of this disclosure, comprises Fe in an atomic content y3, wherein 0.15 < y3 < 0.50 relative to M'. In another embodiment, 0.20 < y3 < 0.40 relative to M'. In another embodiment, 0.28 < y3 < 0.38 relative to M'. For example, y3 is 0.28, 0.29, 0.30, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37 or 0.38, relative to M'. In another embodiment, y3 is 0 relative to M'.

[0081] In one embodiment, the cathode active material obtainable by a process according to the second aspect of this disclosure, comprises Mn in an atomic content z3, wherein 0.15 < z3 < 0.50 relative to M'. In another embodiment, 0.20 < z3 < 0.40 relative to M'. In another embodiment, 0.28 < z3 < 0.38 relative to M'. For example, z3 is 0.28, 0.29, 0.30, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37 or 0.38, relative to M'.

[0082] In one embodiment, the cathode active material obtainable by a process according to the second aspect of this disclosure, comprises Zn in an atomic content q3, wherein 0.01 < q3 < 0.07 relative to M'. In another embodiment, 0.01 < q3 < 0.05 relative to M'. In another embodiment, 0.02 < q3 < 0.05 relative to M'. For example, q3 is 0.02, 0.03, 0.04 or 0.05 relative to M'. In another embodiment, q3 is 0 relative to M'.

[0083] In one embodiment, the cathode active material obtainable by a process according to the second aspect of this disclosure, comprises Ti in an atomic content f3, wherein 0.01 < f3 < 0.17 relative to M'. In another embodiment, 0.05 < f3 < 0.14 relative to M'. In another embodiment, 0.07 < f3 < 0.13 relative to M'. For example, f3 is 0.07, 0.08, 0.09, 0.10, 0.11, 0.12 or 0.13 relative to M'. In another embodiment, f3 is 0 relative to M'.

[0084] In one embodiment, the cathode active material obtainable by a process according to the second aspect of this disclosure, comprises Si in an atomic content a3, wherein 0.0005 < a3 < 0.003 relative to M'. In another embodiment, 0.0005 < a3 < 0.0015 relative to M'. For example, a3 is 0.0005, 0.0006, 0.0007, 0.0008, 0.0009, 0.001, 0.0011, 0.0012, 0.0013, 0.0014 or 0.0015, relative to M'.

[0085] In one embodiment of the cathode active material obtainable by a process according to the second aspect of this disclosure, the Na / M' atomic ratio is between 0.80 and 1.2. In another embodiment, the Na / M' atomic ratio is between 0.80 and 1.1. For example, the Na / M' atomic ratio is 0.80, 0.85, 0.90, 0.95, 0.96, 0.97, 0.98, 0.99, 1.00, 1.01, 1.02, 1.03, 1.04, 1.05, 1.06, 1.07, 1.08, 1.09 or 1.10.

[0086] In one embodiment, the cathode active material obtainable by a process according to the second aspect of this disclosure, comprises Ni in an atomic content x3, 0.15 < x3 < 0.50 relative to M'; Fe in an atomic content y3, wherein 0.15 < y3 < 0.50 relative to M'; Mn in an atomic content z3, wherein 0.15 < z3 < 0.50 relative to M'; Zn in an atomic content q3, wherein q3 is 0 relative to M'; Ti in an atomic content f3, wherein f3 is 0 relative to M'; Si in an atomic content a3, wherein 0.0005 < a3 < 0.003 relative to M', a Na / M' atomic ratio between 0.80 and 1.0, a Sixps / Siicp ratio higher than 1, and wherein the cathode active material comprises particles with a median particle size D50 equal to or lower than 20 pm.

[0087] In one embodiment, the cathode active material obtainable by a process according to the second aspect of this disclosure, is according to the formula (III) NawNix4Fey4Mnz4 Znq4Tif4Sia4O2, wherein 0.80 < w' < 1.50; 0.10 < x4 < 0.60; 0.0 < y4 < 0.60; 0.10 < z4 < 0.60; 0.0 < q4 < 0.10; 0.0 < f4 < 0.20; 0.0001 < a4 < 0.005; wherein x4, y4, z4, q4, f4 and a4 are determined by ICP-OES, and x4+y4+z4+q4+f4+a4 is 1, the Sixps / Siicp ratio is higher than 1, wherein Sixps is the molar fraction of Si as determined by XPS analysis, and Siicp is the molar fraction of Si as determined by ICP-OES analysis, and wherein the cathode active material comprises particles with a median particle size D50 equal to or lower than 20 pm.

[0088] In one embodiment, the cathode active material obtainable by a process according to the second aspect of this disclosure, is according to the formula (III), wherein 0.15 < x4 < 0.50. In another embodiment, 0.20 < x4 < 0.40. In another embodiment, 0.28 < x4 < 0.38. For example, x4 is 0.28, 0.29, 0.30, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37 or 0.38.

[0089] In one embodiment, the cathode active material obtainable by a process according to the second aspect of this disclosure, is according to the formula (III), wherein 0.15 < y4 < 0.50. In another embodiment, 0.20 < y4 < 0.40. In another embodiment, 0.28 < y4 < 0.38. For example, y4 is 0.28, 0.29, 0.30, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37 or 0.38. In another embodiment, y4 is 0.

[0090] In one embodiment, the cathode active material obtainable by a process according to the second aspect of this disclosure, is according to the formula (III), wherein 0.15 < z4 <0.50. In another embodiment, 0.20 < z4 < 0.40. In another embodiment, 0.28 < z4 < 0.38.For example, z4 is 0.28, 0.29, 0.30, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37 or 0.38.

[0091] In one embodiment, the cathode active material obtainable by a process according to the second aspect of this disclosure, is according to the formula (III), wherein 0.01 < q4 < 0.07. In another embodiment, 0.01 < q4 < 0.05. In another embodiment, 0.02 < q4 < 0.05. For example, q4 is 0.02, 0.03, 0.04 or 0.05. In another embodiment, q4 is 0.

[0092] In one embodiment, the cathode active material obtainable by a process according to the second aspect of this disclosure, is according to the formula (III), wherein 0.01 < f4 < 0.17. In another embodiment, 0.05 < f4 < 0.14. In another embodiment, 0.07 < f4 < 0.13. For example, f4 is 0.07, 0.08, 0.09, 0.10, 0.11, 0.12 or 0.13. In another embodiment, f4 is 0.

[0093] In one embodiment, the cathode active material obtainable by a process according to the second aspect of this disclosure, is according to the formula (III), wherein 0.0005 < a4 < 0.003. In another embodiment, 0.0005 < a4 < 0.0015. For example, a4 is 0.0005, 0.0006, 0.0007, 0.0008, 0.0009, 0.001, 0.0011, 0.0012, 0.0013, 0.0014 or 0.0015.

[0094] In one embodiment, the cathode active material obtainable by a process according to the second aspect of this disclosure, is according to the formula (III), wherein 0.8 < w' < 1.2. In another embodiment, 0.8 < w' < 1.1. For example, w' is 0.80, 0.85, 0.90, 0.95, 0.96, 0.97, 0.98, 0.99, 1.00, 1.01, 1.02, 1.03, 1.04, 1.05, 1.06, 1.07, 1.08, 1.09 or 1.10.

[0095] In one embodiment, the cathode active material is according to the formula (III), wherein 0.95 < w' < 1.1; 0.15 < x4 < 0.50; 0.15 < y4 < 0.50; 0.15 < z4 < 0.50; q4 is 0; f4 is 0; 0.0005 < a4 < 0.003, the Sixps / Siicp ratio is higher than 1, wherein Sixps is the molar fraction of Si as determined by XPS analysis, and Siicp is the molar fraction of Si as determined by ICP-OES analysis, and wherein the cathode active material comprises particles with a median particle size D50 equal to or lower than 20 pm.

[0096] In one embodiment, the cathode active material is according to the formula (III), wherein 0.9 < w' < 1.2; 0.15 < x4 < 0.50; 0.15 < y4 < 0.50; 0.15 < z4 < 0.50, q4 is 0; f4 is 0; 0.0005 < a4 < 0.0015, and the Sixps / Siicp ratio is higher than 100, and wherein the cathode active material comprises particles with a median particle size D50 equal to or lower than 20 pm.

[0097] In one embodiment, the cathode active material is according to the formula (III), wherein 0.9 < w' < 1.2; 0.20 < x4 < 0.40; 0.20 < y4 < 0.40; 0.20 < z4 < 0.40, q4 is 0; f4 is 0; 0.0005 < a4 < 0.0015, the Sixps / Siicp ratio is higher than 100, and wherein the cathode active material comprises particles with a median particle size D50 equal to or lower than 10 pm.

[0098] In one embodiment, the cathode active material obtainable by a process according to the second aspect of this disclosure, comprises Si in a content Sixps and Siicp , wherein the Sixps / Siicp ratio is higher than 5. In another embodiment, the Sixps / Siicp ratio is higher than 10. In another embodiment, the Sixps / Siicp ratio is higher than 50. In another embodiment, the Sixps / Siicp ratio is higher than 100. In another embodiment, the Sixps / Siicp ratio is higher than 500. In another embodiment, the Sixps / Siicp ratio is higher than 700. For example, the Sixps / Siicp ratio is 700, 720, 729, 750, 780, 800, 820, 850, 880, 900, 927, 950, 980, or 1000.Battery

[0099] In a fourth aspect, the present disclosure relates to a battery comprising a cathode active material suitable for use in rechargeable batteries across a wide range of electrically powered devices and systems. The battery may be integrated into various applications that utilize electricity as a primary or auxiliary energy source.

[0100] 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.

[0101] Transportation applications include electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), extended-range electric vehicles (EREVs), and fuel cell electric vehicles (FCEVs). These vehicles may be designed for passenger or freight transport and may operate on ground, rail, marine, aerospace, or aviation platforms. Additionally, the battery may be used in two-wheeler transportation systems. Further applications include defense systems and medical devices, where reliable and compact energy sources are required.

[0102] In a fifth aspect, the present disclosure provides the use of a battery according to third aspect of 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 uninterruptiblepower 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.

[0103] 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, fourth and fifth aspect of the present disclosure. Additionally, this disclosure is intended to cover the combination of all embodiments listed above.EXPERIMENTAL ANALYSIS USED IN THE EXAMPLES

[0104] The following analysis methods are used in the Examples.A) Inductively Coupled Plasma - Optical Emission Spectrometry (ICP-OES) analysis

[0105] The amount of Na, Ni, Fe, Mn, Ti, Zn and Si in the cathode active material powder is determined by the ICP-OES method using an Agilent ICP 720-ES (Agilent Technologies). 1 gram of a powder sample is dissolved into 50 mL high purity hydrochloric acid in an Erlenmeyer flask. The flask is covered by a watch glass and heated on a hot plate at 380 °C until complete dissolution of the sample. After being cooled to room temperature, the solution and the rinsing water of Erlenmeyer flask are transferred to a 250 mL volumetric flask. Afterwards, the volumetric flask is filled with distilled water up to the 250 mL mark, followed by complete homogenization. An appropriate amount of solution is taken out by pipette and transferred into a 250 mL volumetric flask for the 2nd dilution, where the volumetric flask is filled with internal standard and 10% hydrochloric acid up to the 250 mL mark and then homogenized. Finally, this solution is used for ICP-OES measurement. The contents of Ni, Mn, Fe, and Si are expressed as wt.% of the total of these contents. Another suitable solvent can be used to fully dissolve the positive electrode active material powder samples.B) Tap density (TD) analysis

[0106] tap density is measured with the standard test method (ASTM-B527) using Dual Autotap of Quantachrome. A graduated measuring cylinder (100 mL) containing a specific amount (W) of the positive electrode active material powder is mechanically tapped for 5,000 times with the frequency of 235~265 tap / min, wherein the specific amount (W) is between 50.0 grams and 100.0 grams. The volume (V) of the powder after tapping is measured and then the TD is calculated from the equation TD=W[g] / V[mL].C) Scanning Electron Microscopy (SEM) analysis

[0107] The morphology of a cathode active material is analyzed by a Scanning Electron Microscopy (SEM) technique. The measurement is performed using a ZEISS SIGMA 300 under a high vacuum environment of 8xl0-6Pa at 25 °C. The particles in the image should be well distributed therefore avoiding overlap between particles. This can be achieved by pouring a small amount of powder sample to the adhesive attached on the SEM sample holder and blowing dry air to remove the excess powder.D) Particle size distribution (PSD) analysis

[0108] The particle size of the cathode active material powders is measured using a Malvern Mastersizer 3000 equipped with an Aero S dry dispersion accessory. The powders are introduced into the instrument through a dry feeder system, where they are dispersed in a stream of compressed air. To ensure effective dispersion and prevent agglomeration, the air pressure is set at 2 bars. The D50 value is defined as the median particle size at which 50% of the cumulative volume is smaller and 50% is larger. Span is defined as (D90-D10) / D50.E) Powder X-ray Diffraction (XRD) analysis

[0109] XRD patterns are recorded on a Bruker D8 Advance X-ray diffractometer in the 15-75 2-theta range in a 0.015 degree scan step. Scan speed is set to 3.0 degrees per minute. The copper target X-ray tube is operated at 40KV and 40mA. The LynxEye XE-T detector is used to capture diffracted X-rays at 3.3 degree opening. The collected XRD patterns comprise KAIpha Cu radiations with typical wavelengths KAIphal =1.5418 A. The incident beam optic setup comprises a 1-degree divergence slit (DS) and 2.5 degree vertical Soller slit. The diffracted beam optic setup includes an automatic anti-scatter slit (SS), and 2.5 degree vertical Soller slit. To prevent fluctuations, the temperature is kept near room temperature all the time.F) Exposure test

[0110] The carbon and moisture exposure test are conducted by evenly spreading 40 grams of positive electrode active material on a 95 x 95 mm2 dish and placing the dish inside a 30 °C chamber. The atmosphere of the chamber is controlled to have a relative humidity level of 50%. After 3 days, each of the positive electrode active material powders is taken for carbon analysis, particle size distribution analysis and coin cell analysis. The results are summarized in Table IV.G) Carbon analysis

[0111] The content of carbon of the positive electrode active material powder is measured by Horiba Emia-Expert carbon / sulfur analyzer. 1 gram of the positive electrode active materialpowder is placed in a ceramic crucible in a high frequency induction furnace. 2.1 grams of tungsten and 0.9 grams of tin are added into the crucible as accelerators. The powder is heated at a programmable temperature wherein gases produced during the combustion are then analyzed by Infrared detectors. The analysis of CO2 and CO determines the carbon concentration.H) X-ray Photoelectron Spectroscopy (XPS)

[0112] In the present invention, X-ray photoelectron spectroscopy (XPS) is used to analyze the surface of cathode active material powder particles. In XPS measurement, the signal is acquired from the first few nanometers (e.g., 1 nm to 10 nm) of the uppermost part of a sample, i.e., surface layer. Therefore, all elements measured by XPS are contained in the surface layer.

[0113] For the surface analysis of positive electrode active material powder particles, XPS measurement is carried out using a Thermo K-o+ spectrometer. Monochromatic Al Ko radiation (hu= 1486.6 eV) is used with a spot size of 400 pm and a measurement angle of 45°. A wide survey scan to identify elements present at the surface is conducted at 200 eV pass energy. Cis peak having a maximum intensity (or centered) at a binding energy of 284.8 eV is used as a calibrate peak position after data collection. Accurate narrow scans are performed afterwards at 50 eV for at least 10 scans for each identified element to determine the precise surface composition.

[0114] Curve fitting is done with CasaXPS Version2.3.19PR1.0 using a Shirley-type background treatment and Scofield sensitivity factors. The fitting parameters are according to Table I. Line shape GL(30) is the Gaussian / Lorentzian product formula with 70% Gaussian line and 30% Lorentzian line. LA(o, 0, m) is an asymmetric line-shaped where a and P define tail spreading of the peak and m define the width.Table I. XPS fitting parameters for Ni2p3, Mn2p3, Fe2p3, and Silp.I) Coin cell analysisII) Coin cell preparation

[0115] The method comprises forming a slurry comprising a cathode active material powder, a conductive material (Super P, Timcal), and a binder (KF 9700, Kureha) in a weight ratio of 92:4.0:4.0, respectively, in a solvent (NMP, Mitsubishi). The slurry is homogenized using a high-speed homogenizer. The homogenized slurry is then uniformly applied to one side of an aluminum foil substrate using a doctor blade coater with a gap of 230 pm. The coated foil is subsequently dried in an oven at a temperature of 120 °C. Following the drying step, the coated foil is pressed using a calendaring tool and then subjected to a second drying process in a vacuum oven to ensure complete removal of the solvent from the electrode film.

[0116] The coin cell is assembled within an argon-filled glovebox to prevent contamination. A separator (glass microfiber filter) is placed between the positive electrode and a piece of sodium foil, which serves as the negative electrode. An electrolyte solution comprising 0.6 M NaPF6 in a mixture of propylene carbonate (PC) and fluoroethylene carbonate (FEC) in a volume ratio of 3:7 is added between the separator and the electrodes. The coin cell is then sealed to prevent electrolyte leakage, completing the assembly process12) Testing method

[0117] The tests for discharge capacity (DQ) and irreversible capacity (Qirr) are performed using coin cells with electrodes consisting of 92 wt% of the cathode active material described in this invention. The electrode loading is approximately 9.5 mg / cm2. The discharge capacity for the first cycle (DQ1) is measured within the voltage range of 4.0-2.2 V at a rate of 1C (expressed in mAh / g) at a temperature of 25°C.100TABLE II: CYCLING SCHEDULE FOR COIN CELL TESTING METHODEXAMPLES

[0118] The present disclosure is further illustrated by the following examples.Example 1

[0119] A cathode active material further called EX1.1 is obtained following these steps:1) mixing Nio.3Mno.3Feo.3(OH)2 with sodium carbonate to obtain a first mixture having a Na / (Ni, Mn, Fe) ratio is 1.02;2) heating the first mixture at 900 °C for 12 hours under air to obtain a first heated mixture. Then, the first heated mixture is crushed and sieved to obtain a crushed and sieved material with a median particle size D50 of about 4.5 pm,3) mixing the crushed and sieved material with 1000 ppm trimethoxymethylsilane, which was dissolved in ethanol (45 ml / kg liquid to solid ratio), with respect to the total molar contents of Ni, Mn, and Fe to obtain a second mixture. Then, the solution was stirred for 1 min,4) drying the second mixture at 60 °C for 6 hours to obtain a dried second mixture,5) heating the dried second mixture at 250 °C for 6 hours under air, to obtain EX1.1.

[0120] A cathode active material further called EX1.2 was obtained following the same steps as for EX1.1, except that 500 ppm trimethoxymethylsilane was used in step 3).Example 2

[0121] A cathode active material further called EX2.1 is obtained following these steps:1) mixing Nio.3Mno.3Feo.3(OH)2 with sodium carbonate to obtain a first mixture having a Na / (Ni, Mn, Fe) ratio is 1.02;2) heating the first mixture at 900 °C for 12 hours under air to obtain a first heated mixture. Then, the first heated mixture is crushed and sieved to obtain a crushed and sieved material with a median particle size D50 of about 10 pm,3) mixing the crushed and sieved material with 1000 ppm trimethoxymethylsilane, which was dissolved in ethanol (45 ml / kg liquid to solid ratio), with respect to the total molar contents of Ni, Mn, and Fe to obtain a second mixture. Then, the solution was stirred for 1 min,4) drying the second mixture at 60 °C for 6 hours to obtain a dried second mixture,5) heating the dried second mixture at 250 °C for 6 hours under air, to obtain EX2.1.

[0122] A cathode active material further called EX2.2 was obtained following the same steps as for EX2.1, except that 500 ppm trimethoxymethylsilane were used on step 3).Example 3

[0123] A cathode active material further called EX3.1 is obtained following these steps:1) mixing Nio.3Mno.3Feo.3(OH)2 with sodium carbonate to obtain a first mixture having a Na / (Ni, Mn, Fe) ratio is 1.02;2) heating the first mixture at 900 °C for 12 hours under air to obtain a first heated mixture. Then, the first heated mixture is crushed and sieved to obtain a crushed and sieved material with a median particle size D50 of about 4.5 pm,3) mixing the crushed and sieved material with 1000 ppm trimethoxymethylsilane, which was dissolved in ethanol (45 ml / kg liquid to solid ratio), with respect to the total molar contents of Ni, Mn, and Fe to obtain a second mixture. Then, the solution was stirred for 1 min,4) drying the second mixture at 60 °C for 6 hours to obtain a dried second mixture,5) heating the dried second mixture at 350 °C for 6 hours under air, to obtain EX3.1.

[0124] A cathode active material further called EX3.2 was obtained following the same steps as for EX3.1, except that the dried second mixture was heated at 80 °C for 6 hours.

[0125] A cathode active material further called EX4.1 is obtained following these steps:1) mixing Nio.3Mno.3Feo.3(OH)2 with sodium carbonate to obtain a first mixture having a Na / (Ni, Mn, Fe) ratio is 1.02;2) heating the first mixture at 900 °C for 12 hours under air to obtain a first heated mixture. Then, the first heated mixture is crushed and sieved to obtain crushed and sieved material with a median particle size D50 of about 10 pm,3) mixing the crushed and sieved material with 1000 ppm trimethoxymethylsilane, which was dissolved in ethanol (45 ml / kg liquid to solid ratio), with respect to the total molar contents of Ni, Mn, and Fe to obtain a second mixture. Then, the solution was stirred for 1 min,4) drying the second mixture at 60 °C for 6 hours to obtain a dried second mixture,5) heating the dried second mixture at 350 °C for 6 hours under air, to obtain EX4.1.Example 5

[0126] A cathode active material further called EX5.1 is obtained following these steps:1) mixing Nio.38Mno.48Zno.o4Tio.io(OH)2 with sodium carbonate to obtain a first mixture having a Na / (Ni, Mn, Zn, Ti) ratio is 0.85;2) heating the first mixture at 900 °C for 12 hours under air to obtain a first heated mixture. Then, the first heated mixture is crushed and sieved to obtain crushed and sieved material with a median particle size D50 of about 6.5 pm,3) mixing the crushed and sieved material with 1000 ppm trimethoxymethylsilane, which was dissolved in ethanol (45 ml / kg liquid to solid ratio), with respect to the total molar contents of Ni, Mn, Zn and Ti to obtain a second mixture. Then, the solution was stirred for 1 min,4) drying the second mixture at 60 °C for 6 hours to obtain a dried second mixture,5) heating the dried second mixture at 250 °C for 6 hours under air, to obtain EX5.1.

[0127] A cathode active material further called EX5.2 was obtained following the same steps as for EX5.1, except that the crushed and sieved material with a median particle size D50 of about 12.5 pm.

[0128] A cathode active material further called CEX1 is obtained following these steps:1) mixing Nio.3Mno.3Feo.3(OH)2 with sodium carbonate to obtain a first mixture having a Na / (Ni, Mn, Fe) ratio is 1.02;2) heating the first mixture at 900 °C for 12 hours under air to obtain a first heated mixture. Then, the first heated mixture is crushed and sieved to obtain a material with median particle size D50 of about 4.5 pm.

[0129] A cathode active material further called CEX2 is obtained following these steps:1) mixing Nio.3Mno.3Feo.3(OH)2 with sodium carbonate to obtain a first mixture having a Na / (Ni, Mn, Fe) ratio is 1.02;2) heating the first mixture at 900 °C for 12 hours under air to obtain a first heated mixture. Then, the first heated mixture is crushed and sieved to obtain a material with median particle size D50 of about 10 pm.Comparative Example 3

[0130] A cathode active material further called CEX3 is obtained following these steps:1) mixing Nio.38Mno.48Zno.o4Tio.io(OH)2 with sodium carbonate to obtain a first mixture having a Na / (Ni, Mn, Zn, Ti) ratio is 0.85;2) heating the first mixture at 900 °C for 12 hours under air to obtain a first heated mixture. Then, the first heated mixture is crushed and sieved to a material with a median particle size D50 of about 6.5 pm.Comparative Example 4

[0131] A cathode active material further called CEX4 is obtained following these steps:1) mixing Nio.38Mno.48Zno.o4Tio.io(OH)2 with sodium carbonate to obtain a first mixture having a Na / (Ni, Mn, Zn, Ti) ratio is 0.85;2) heating the first mixture at 900 °C for 12 hours under air to obtain a first heated mixture. Then, the first heated mixture is crushed and sieved to a material with a median particle size D50 of about 12.5 pm.RESULTSTable III: the Na / M ratio, wherein M includes Ni, Fe, Mn; the Ni, Fe, Mn, Si mol% as measured by ICP-OES, the median particle size D50, and the silane wt% of the example and comparative examples.

[0132] According to the results of Table III, the examples according to this disclosure show a Sixps / Siicp ratio higher than 0 indicating that a Si-based compound is present on the surface of the cathode active material. Additionally, for EX1.1 and EX2.1 the Sixps / Siicp ratio is higher than 700, indicating that the Si-based compound is mainly on the surface of the cathodeactive material. On the other hand, the ICP results show that the comparative examples have no content of Si.Table IV: the median particle size D50 and total carbon content before and after the 3-day exposure test for the examples and comparative examples.

[0133] As it can be observed, the median particle size D50 of the comparative examples (CEX1 and CEX2) has significantly increased after the exposure test compared to the corresponding examples (EX1.1 and EX2.1), indicating that the presence of Si improves the stability of the powder particles.

[0134] The same effect can be also observed by analyzing the carbon content after the exposure test, wherein the carbon content of CEX2 has increased >9 fold, indicating a mayor formation of carbonate salts when compared to the corresponding examples EX2. l and EX2.2. Therefore, a cathode active material according to this disclosure shows improved air and / or moisture stability and also higher lifetime.Table V: Electrochemical properties before and after the 3-day exposure test.

[0135] The DQ1 and DQ22 / DQ2 values after the 3-day test of the EX1.1 and EX.1.2 are higher than the corresponding comparative example CEX1, indicating that presence Si improves stability and cyclic performance. Therefore, a cathode active material according to this disclosure might show capacity retention.

[0136] Moreover, the discharge capacity (DQ1) before the exposure test of EX1.1 and EX1.2 (D50= 4.5 pm) are higher than the EX2.1 and EX2.2 (D50= 10 pm) respectively, indicating that a cathode active material comprising particles with a narrow median particle size D50 has an improved discharge capacity.

[0137] The discharge capacity (DQ1) and capacity retention (DQ22 / DQ2) of the EX1.1 containing 0.1 wt% of Si are higher than the corresponding DQ1 and DQ22 / DQ2 of EX1.2 containing 0.05 wt% of Si. Therefore, a cathode active material comprising 0.1 wt% of Si might have improved stability and battery performance.

[0138] The capacity retention (DQ22 / DQ2) of the EX1.1 is higher than the corresponding DQ22 / DQ2 for EX3.1. The only difference between these examples is the heating temperature during step 5), indicating that the heating temperature might play a role in the stability of the powder particles. The same effect can also be observed between EX2.1 and Ex 4.2. Therefore, a cathode active material obtainable by a process wherein the heating temperature of step 5) is lower than 350 °C or lower than 300 °C, might show an improved stability.

Claims

1. CLAIMS1. A cathode active material for sodium batteries, wherein the cathode active material comprises Na, M, and O, wherein M comprises:Ni in an atomic content x, wherein 0.10 < x < 0.60 relative to M,Fe in an atomic content y, wherein 0.0 < y < 0.60 relative to M,Mn in an atomic content z, wherein 0.10 < z < 0.60 relative to M,Zn in an atomic content q, wherein 0.0 < q < 0.10 relative to M,- Ti in an atomic content f, wherein 0.0 < f < 0.20 relative to M,Si in an atomic content a, wherein 0.0001 < a < 0.005 relative to M, wherein x, y, z, and a are determined by Inductively Coupled Plasma - Optical Emission Spectrometry, x+y+z+q+f+a is 1, the Na / M atomic ratio is between 0.8 to 1.5, and the Sixps / Siicp ratio is higher than 1, wherein Sixps is the molar fraction of Si as determined by XPS analysis, and Siicp is the molar fraction of Si as determined by Inductively Coupled Plasma - Optical Emission Spectrometry, and wherein the cathode active material comprises particles with a median particle size D50 equal to or lower than 20 pm.

2. A cathode active material according to claim 1, having a median particle size D50 equal to or lower than 10 pm.

3. A cathode active material according to claim 1 to 2, wherein the Sixps / Siicp ratio is higher than 10.

4. A cathode active material according to any of the claims 1 to 3, wherein a is between 0.0006 and 0.0015.

5. A cathode active material according to claim 1, wherein the cathode active material is according to the formula (I) NawNixiFeyiMnziZnqiTifiSiaiO2, wherein 0.80 < w < 1.50; 0.10 < xl < 0.60; 0.0 < yl < 0.60; 0.10 < zl < 0.60; 0.0 < ql < 0.10; 0.0 < fl < 0.20; 0.0001 < al < 0.005; wherein xl, yl, zl, ql, fl and al are determined by Inductively Coupled Plasma - Optical Emission Spectrometry, and xl+yl+zl+ql+fl+al is 1.

6. A cathode active material according to claim 5, wherein 0.15 < xl < 0.50, 0.15 < yl< 0.50, 0.15 < zl < 0.50, ql is 0 and fl is 0.

7. A cathode active material according to claim 5, wherein 0.15 < xl < 0.50; yl is 0; 0.10 < zl < 0.60; 0.1 < ql < 0.07; 0.05 < fl < 0.14.

8. A cathode active material according to any of the claims 5 to 7, wherein 0.0006 < al< 0.0015.

9. A method for manufacturing a cathode active material according to any of the claims 1 to 8, wherein the method comprises the following steps:1) mixing a metal-based precursor with a sodium source to obtain a first mixture;2) heating the first mixture at a temperature between 700 °C and 1100 °C, to obtain a first heated material;3) crushing and sieving the first heated material to obtain a crushed and sieved material with a median particle size D50 equal to or lower than 20 pm;4) mixing the crushed and sieved material with a Si source to obtain a second mixture;5) drying the second mixture at a temperature between 40 °C and 80 °C, to obtain a dried second mixture; and6) heating the dried second mixture at a temperature between 50 °C and 500 °C, to obtain the cathode active material.

10. A method according to claim 9, wherein the metal-based precursor is according to formula (II) Nix2Fey2Mnz2ZnqiTifi(OH)2, wherein 0.10 < x2 < 0.60; 0.0 < y2 < 0.60; 0.10 < z2 < 0.60; 0.0 < q2 < 0.10; 0.0 < f2 < 0.20; wherein x2, y2, z2, q2 and f2 are determined by Inductively Coupled Plasma - Optical Emission Spectrometry, and x2+y2+z2+q2+f2 is 1.

11. A method according to claim 9 or 10, wherein the sodium source is NaOH, Na2COs or a mixture thereof.

12. A method according to any of the claims 9 to 11, wherein the first mixture is heated at about 900 °C for a period of time between 8 to 14 hours.

13. A method according to any of the claims 9 to 12, wherein the Si source is an organosilane.

14. A battery comprising a cathode active material according to any of the claims 1 to 8.

15. The use of a 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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