Lithium nickel-based complex oxides as positive electrode active materials for rechargeable lithium-ion batteries

Abstract

The present invention provides a positive electrode active material for a lithium-ion rechargeable battery, wherein the positive electrode active material contains Li, M', and oxygen, where M' contains: - Ni at x with respect to the content of M' being between 60.0 mol% and 95.0 mol%; - Co at y with respect to the content of M', where 0 < y < 40.0 mol%; - Mn at z with respect to the content of M', where 0 < z < 70.0 mol%; - D at a with respect to the content of M', where 0 < a < 2.0 mol%, where D includes elements other than Li, O, Ni, Co, Mn, F, W, and B; - F at b with respect to the content of M', where b > 0, preferably between 0.1 mol% and 4.0 mol%; - W at c with respect to the content of M' being between 0.1 mol% and 4.0 mol%; - B at e with respect to the content of M', where 0 < e < 4.0 mol%; and, - where x, y, z, a, e, and c are measured by inductively coupled plasma-optical emission spectrometry (ICP-OES), - where b is measured by ion chromatography (IC), - where x + y + z + a + b + c + e = 100.0 mol%, and where the positive electrode active material has an F content F defined by formula (I) A and a W content W defined by formula (II) A , where the positive electrode active material has an F content F B and a W content W B , where F B and W B are determined by XPS analysis, where F B and W B [[ID=I6]]are each expressed as a mole fraction compared to the sum of the mole fractions of Co, Mn, Ni, F, W, and B measured by X-ray photoelectron spectroscopy, where the ratio F B / F A = 1.0, where the ratio W B / W A > 1.0.

Description

[0001] Technical Field and Background Technology

[0002] This invention relates to a lithium nickel-based oxide positive electrode active material for lithium-ion secondary batteries (LIBs) suitable for electric vehicle (EV) and hybrid electric vehicle (HEV) applications. The lithium nickel-based oxide positive electrode active material comprises lithium transition metal-based oxide particles containing fluorine.

[0003] Positive electrode active materials are defined as materials that are electrochemically active in a positive electrode. For active materials, it is essential to understand their ability to capture and release lithium ions when subjected to voltage changes over a predetermined time period.

[0004] Therefore, the object of the present invention is to provide a positive electrode active material having one or more improved properties, such as reduced carbon content and improved cycle life (as indicated by capacity decay rate (QF) value) in electrochemical cells.

[0005] Acknowledgments

[0006] This invention was completed with the support of the Materials / Components Technology Development Program of the Korea Assessment Industrial Technology Research Institute, funded by the Ministry of Trade, Industry and Energy (MOTIE, Republic of Korea). [Project Title: Development of High-Power (High-Discharge-Rate) Lithium-Ion Secondary Batteries with 8C Rate Rating / Project No.: 20011287 / Contribution Rate: 100%] Summary of the Invention

[0007] This objective is achieved by providing a positive electrode active material for lithium-ion batteries, wherein the positive electrode active material comprises Li, M', and oxygen, wherein M' comprises:

[0008] - For Ni with a content of M' between 60.0 mol% and 95.0 mol%, preferably, the content of x is between 80.0 mol% and 95 mol%.

[0009] -Co with a content of M' of y, where 0 ≤ y ≤ 40.0 mol%.

[0010] -Mn with a content of z relative to M', where 0≤z≤70.0mol%.

[0011] - D with a content of a relative to M', wherein 0 ≤ a ≤ 2.0 mol%, wherein D includes elements other than Li, O, Ni, Co, Mn, F, W and B, and preferably D includes at least one element from the group consisting of: Al, Ba, Ca, Cr, Fe, Mg, Mo, Nb, S, Si, Sr, Ti, Y, V, Zn and Zr;

[0012] - F with a content of b relative to M', where b>0, preferably between 0.1 mol% and 4.0 mol%;

[0013] -W with a content of c relative to M', where c>0, preferably between 0.1 mol% and 4.0 mol%;

[0014] -Optionally, relative to the content of M' of S is d, where 0 ≤ d ≤ 4.0 mol%.

[0015] - Relative to B with a content of e, where 0 ≤ e ≤ 4.0 mol%; and,

[0016] -where x, y, z, a, e, and c are measured by ICP-OES.

[0017] -where b is measured by IC,

[0018] -where x+y+z+a+b+c+d+e is 100.0 mol%.

[0019] The positive electrode active material thereon has the following definition: F content F A and defined as W content A ,

[0020] The positive electrode active material has an F content of F B and W content W B , where F B and W B F was determined through XPS analysis. B and W B Each is expressed as a mole fraction relative to the sum of the mole fractions of Co, Mn, Ni, F, W, S, and B as measured by XPS analysis.

[0021] Where the ratio F B / F A >1.0,

[0022] Where the ratio W B / W A >1.0.

[0023] In some cases, the positive electrode active material further comprises S in a content of d, wherein d > 0, preferably 0.01 mol% ≤ d ≤ 3.0 mol%, wherein the positive electrode active material has a defined S content A ,

[0024] The positive electrode active material has an S content determined by XPS analysis. B S B Mole fraction expressed as a sum of the mole fractions of Co, Mn, Ni, F, W, S, and B as measured by XPS analysis.

[0025] Where the ratio S B / S A >1.0.

[0026] This invention relates to the following embodiments:

[0027] Implementation Plan 1

[0028] In a first aspect, the present invention relates to a positive electrode active material for a lithium-ion battery, wherein the positive electrode active material comprises Li, M' and oxygen, wherein M' comprises:

[0029] -Ni relative to x with an M' content between 60.0 mol% and 95.0 mol%;

[0030] -Co with a content of M' of y, where 0 ≤ y ≤ 40.0 mol%.

[0031] -Mn with a content of z relative to M', where 0≤z≤70.0mol%.

[0032] - D with a content of a relative to M', wherein 0 ≤ a ≤ 2.0 mol%, wherein D includes elements other than Li, O, Ni, Co, Mn, F, W and B, and preferably D includes at least one element from the group consisting of: Al, Ba, Ca, Cr, Fe, Mg, Mo, Nb, S, Si, Sr, Ti, Y, V, Zn and Zr;

[0033] - F relative to M' content of b between 0.1 mol% and 4.0 mol%;

[0034] -W relative to M' content between 0.1 mol% and 4.0 mol% of c;

[0035] -Optionally, relative to the content of M' of S is d, where 0 ≤ e ≤ 4.0 mol%.

[0036] -B with a content of e relative to M', where 0 ≤ e ≤ 4.0 mol%; and

[0037] -where x, y, z, a, e, d, and c are measured by ICP-OES.

[0038] -where b is measured by IC,

[0039] -where x+y+z+a+b+c+d+e is 100.0 mol%.

[0040] The positive electrode active material thereon has the following definition: F content F A and defined as W content A ,

[0041] The positive electrode active material has an F content of F B and W content W B , where F B and W B F was determined through XPS analysis. B and W B Each is expressed as a mole fraction relative to the sum of the mole fractions of Co, Mn, Ni, F, W, S, and B as measured by XPS analysis.

[0042] Where the ratio F B / F A >1.0,

[0043] Where the ratio W B / W A >1.0.

[0044] Preferably, F B / F A >2.0, more preferably F B / F A >5.0, and most preferably F B / F A ≥10.0.

[0045] Preferably, F B / F A <60.0, and more preferably F B / F A <50.0, and most preferably F B / F A ≤40.0.

[0046] Preferably, W B / W A >2.0, more preferably W B / W A>5.0, and most preferably W B / W A ≥30.0.

[0047] Preferably, W B / W A <100.0, and more preferably W B / W A <90.0, and most preferably W B / W A ≤85.0.

[0048] Preferably, the Ni content relative to M' is x ≥ 65.0 mol%, and more preferably x ≥ 70.0 mol%, even more preferably greater than 75 mol%.

[0049] Preferably, the Ni content relative to M' is x ≤ 93.0 mol%, and more preferably x ≤ 91.0 mol%, even more preferably less than 87 mol%.

[0050] Preferably, the Co content relative to M' is y > 2.0 mol%, more preferably y ≥ 3.0 mol%, and even more preferably y ≥ 4.0 mol%.

[0051] In one embodiment, the Co content relative to M' is y < 20 mol%, more preferably y < 15 mol%, and even more preferably < 12.5 mol%.

[0052] Preferably, the Mn content z > 1 mol% relative to M', more preferably ≥ 3.0 mol%, and even more preferably z ≥ 4.0 mol%.

[0053] In one embodiment, the Mn content y is less than 20 mol% relative to M', more preferably less than 15 mol%, and even more preferably less than 12.5 mol%.

[0054] Preferably, a is between 0.01 mol% and 2.0 mol% relative to M', and more preferably a is between 0.1 mol% and 1.8 mol%.

[0055] Preferably, B is present in a content between 0.1 mol% and 2 mol%, and even more preferably between 0.2 mol% and 1 mol%.

[0056] Preferably, F is present in a content b between 0.1 mol% and 2 mol%, and even more preferably between 0.2 mol% and 1 mol%.

[0057] Preferably, W exists in a content b between 0.1 mol% and 2 mol%, and even more preferably between 0.2 mol% and 1 mol%.

[0058] In some cases, the positive electrode active material of the present invention further comprises S in a content between 0 and 4.0 mol% relative to M', preferably between 0.1 mol% and 2 mol%, and even more preferably between 0.2 mol% and 1 mol%.

[0059] Preferably, the positive electrode active material is in powder form.

[0060] For completeness, it should be noted that if the symbol “0≤” is used in the definition of this invention to describe the content of an element, it means that the presence of the element is optional.

[0061] Implementation Plan 2

[0062] In the second embodiment, preferably according to embodiment 1, the material contains B in a content of e, where e > 0, preferably 0.01 mol% ≤ e ≤ 4.0 mol%, wherein the positive electrode active material has a defined... B content A ,

[0063] The positive electrode active material has a B content determined by XPS analysis. B B B Mole fraction expressed as a sum of the mole fractions of Co, Mn, Ni, F, W, S, and B as measured by XPS analysis.

[0064] Where ratio B B / B A >1.0.

[0065] Preferably, B B / B A >2.0.

[0066] More preferably, B B / B A >5.0, and most preferably B B / B A ≥20.0.

[0067] Preferably, B B / B A <60.0, and more preferably B B / B A ≤50.0.

[0068] Implementation Plan 3

[0069] In a third aspect, the present invention provides a battery comprising the positive electrode active material of the present invention.

[0070] In another aspect, the present invention provides the use of the battery according to the invention in portable computers, tablet computers, mobile phones, electric vehicles or energy storage systems.

[0071] Implementation Plan 4 :

[0072] The fourth embodiment provides a positive electrode active material for lithium-ion batteries, wherein the positive electrode active material comprises Li, M' and oxygen, wherein M' comprises:

[0073] -Ni relative to x with an M' content between 60.0 mol% and 95.0 mol%;

[0074] -Co with a content of M' of y, where 0 ≤ y ≤ 40.0 mol%.

[0075] - Mn with a content of z relative to M', where 0 ≤ z ≤ 70.0 mol%.

[0076] - D with a content of a relative to M', where 0 ≤ a ≤ 2.0 mol%, wherein D comprises at least one element from the group consisting of: Al, Ba, Ca, Cr, Fe, Mg, Mo, Nb, Si, Sr, Ti, Y, V, Zn, and Zr, and,

[0077] - F relative to M' content of b between 0.1 mol% and 4.0 mol%,

[0078] -W relative to M' content between 0.1 mol% and 4.0 mol% of c,

[0079] - S relative to M' content of d, where 0 ≤ d ≤ 3.0 mol%.

[0080] - Relative to B with a content of e, where 0 ≤ e ≤ 4.0 mol%.

[0081] -where x, y, z, a, d, e, and c are measured by ICP-OES.

[0082] -where b is measured by IC,

[0083] -where x+y+z+a+b+c+d+e is 100.0 mol%.

[0084] The positive electrode active material thereon has the following definition: F content F A and defined as W content A,

[0085] The positive electrode active material has an F content of F B and W content W B , where F B and W B F was determined through XPS analysis. B and W B Each is expressed as a mole fraction relative to the sum of the mole fractions of Co, Mn, Ni, F, W, B, and S as measured by XPS analysis.

[0086] Where the ratio F B / F A >1.0,

[0087] Where the ratio W B / W A >1.0.

[0088] Preferably, F B / F A >2.0.

[0089] Preferably, W B / W A >1.0.

[0090] For completeness, it should be noted that if the symbol “0≤” is used in the definition of this invention to describe the content of an element, it means that the presence of the element is optional.

[0091] Implementation Plan 5

[0092] In the fifth embodiment, preferably according to embodiment 4, the material contains S in a content of d, wherein 0.01 mol% ≤ d ≤ 3.0 mol%, wherein the positive electrode active material has a defined... S content A ,

[0093] The positive electrode active material has an S content determined by XPS analysis. B S B Mole fraction expressed as a sum of the mole fractions of Co, Mn, Ni, F, W, S, and B as measured by XPS analysis.

[0094] Where the ratio S B / S A >1.0.

[0095] Preferably, S B / S A >2.0.

[0096] Implementation Plan 6

[0097] In the sixth embodiment, preferably according to embodiment 4 or 5, the material comprises B in an amount of e, wherein 0.01 mol% ≤ e ≤ 4.0 mol%, wherein the positive electrode active material has a defined... B content A ,

[0098] The positive electrode active material has a B content determined by XPS analysis. B B B Mole fraction expressed as a sum of the mole fractions of Co, Mn, Ni, F, W, S, and B as measured by XPS analysis.

[0099] Where ratio B B / B A >1.0.

[0100] Preferably, B B / B A >2.0.

[0101] Implementation Plan 7

[0102] In a seventh embodiment, the present invention relates to a positive electrode active material comprising Li, M' and oxygen, wherein M' comprises:

[0103] -Ni relative to x with an M' content between 60.0 mol% and 95.0 mol%;

[0104] -Co with a content of M' of y, where 0 ≤ y ≤ 40.0 mol%.

[0105] - Mn with a content of z relative to M', where 0 ≤ z ≤ 70.0 mol%.

[0106] - D with a content of a relative to M', where 0 ≤ a ≤ 2.0 mol%, wherein D comprises at least one element from the group consisting of: Al, B, Ba, Ca, Cr, Fe, Mg, Mo, Nb, S, Si, Sr, Ti, Y, V, Zn, and Zr, and,

[0107] - F relative to M' content of b between 0.1 mol% and 4.0 mol%,

[0108] -W relative to M' content between 0.0 mol% and 4.0 mol% of c,

[0109] -S relative to M' content between 0.01 mol% and 3.0 mol% of d,

[0110] - B with a content of e, where 0 ≤ e ≤ 4.0 mol%.

[0111] -where x, y, z, a, c, d, and e are measured by ICP-OES.

[0112] -where b is measured by IC,

[0113] -where x+y+z+a+b+c+d+e is 100.0 mol%.

[0114] The positive electrode active material thereon has the following definition: F content F A and defined as S content A ,

[0115] The positive electrode active material has an F content of F B , where F B F was determined through XPS analysis. B and S B Each is expressed as a mole fraction relative to the sum of the mole fractions of Co, Mn, Ni, F, W, B, and S as measured by XPS analysis.

[0116] Where the ratio F B / F A >1.0, and

[0117] Where the ratio S B / S A >1.0.

[0118] Preferably, F B / F A >2.0.

[0119] Preferably, S B / S A >2.0. Detailed Implementation

[0120] The positive electrode active material according to the invention generally has one or more of the following advantages: (i) reduced carbon content and (ii) improved cycle life. This is believed to be achieved by positive electrode materials comprising fluorine and tungsten, and optionally boron.

[0121] Typically, the positive electrode material of the present invention comprises secondary particles having a median size D50 of at least 2 μm, and preferably at least 3 μm, as determined by laser diffraction particle size analysis.

[0122] Preferably, the material has a secondary particle median size D50 of up to 16 μm, and more preferably up to 15 μm, as determined by laser diffraction particle size analysis.

[0123] Obviously, other product embodiments according to the invention can be provided by combining the features covered by the different product embodiments described above.

[0124] In another aspect of the invention, the positive electrode material of the invention can be prepared by a method comprising the following steps:

[0125] Step 1) Mix lithium transition metal oxide with an F-containing compound and a W-containing compound to obtain a mixture; and

[0126] Step 2) Heat the mixture in an oxidizing atmosphere at a temperature between 250°C and less than 500°C to obtain the positive electrode active material.

[0127] Preferably, the F-containing compound used in step 1) is PVDF.

[0128] Preferably, the amount of F used in step 1) is between 300 ppm and 3000 ppm relative to the weight of the lithium transition metal oxide. More preferably, the amount of F used in step 1) is between 500 ppm and 2000 ppm relative to the weight of the lithium transition metal oxide.

[0129] Preferably, the W-containing compound used in step 1) is WO3.

[0130] Preferably, the amount of W is between 2000 ppm and 9000 ppm relative to the weight of the lithium transition metal oxide. More preferably, the amount of W used in step 1) is between 3000 ppm and 8000 ppm relative to the weight of the lithium transition metal oxide.

[0131] Furthermore, preferably in step 1), a B-containing compound, preferably H3BO3, is added together with a F- and W-containing compound, wherein the amount of B is between 100 ppm and 3000 ppm relative to the weight of the lithium transition metal oxide.

[0132] Furthermore, the method includes an additional step between step 1 and step 2, wherein the additional step is to combine the mixture from step 1) with a solution containing an amount of an S-containing compound in a weight of 500 ppm to 5000 ppm relative to the lithium transition metal oxide.

[0133] Preferably, the sulfur-containing compound used is Al2(SO4)3.

[0134] Optionally, elements other than those containing Li, O, Ni, Co, Mn, F, W, and B are added to the positive electrode material, wherein preferably, the elements include at least one element from the group consisting of: Al, Ba, Ca, Cr, Fe, Mg, Mo, Nb, S, Si, Sr, Ti, Y, V, Zn, and Zr. Preferably, when preparing transition metal oxides, the element-containing compound is added together with the lithium source in a mixing step. Alternatively, the element-containing compound may be added during precursor preparation.

[0135] In the framework of this invention, ppm refers to a concentration unit, parts per million, meaning 1 ppm = 0.0001 wt%.

[0136] In the following detailed description, preferred embodiments are presented to facilitate practice of the invention. Although the invention has been described with reference to these specific preferred embodiments, it should be understood that the invention is not limited to these preferred embodiments. The invention includes many alternatives, modifications, and equivalents, which will become apparent from the following detailed description and accompanying drawings.

[0137] A) ICP-OES analysis

[0138] The Li, Ni, Mn, Co, W, and B contents, and optionally S contents, of the positive electrode active material powder were measured by inductively coupled plasma optical emission spectroscopy (ICP-OES) using an Agilent ICP 720-OES system. Two grams of the product powder sample were dissolved in 10 mL of high-purity hydrochloric acid in an Erlenmeyer flask. The flask was covered with a glass slide and heated on a hot plate at 380 °C until the precursor was completely dissolved. After cooling to room temperature, the solution from the Erlenmeyer flask was poured into a 250 mL volumetric flask. The volumetric flask was then filled with deionized water to the 250 mL mark and homogenized completely. A suitable amount of solution was pipetted and transferred to a 250 mL volumetric flask for a second dilution, at which point the volumetric flask was filled with internal standard and 10% hydrochloric acid to the 250 mL mark and homogenized. Finally, this 50 mL solution was used for ICP-OES measurements.

[0139] B) PSD

[0140] After dispersing each powder sample in an aqueous medium, the particle size distribution (PSD) of the positive electrode active material powder was measured using laser diffraction particle size analysis with a Malvern Mastersizer 3000 equipped with a Hydro MV wet dispersion attachment. Sufficient ultrasonic irradiation and stirring were applied to improve powder dispersibility, and a suitable surfactant was introduced. D50 was defined as the particle size at 50% of the cumulative volume % distribution obtained from the Malvern Mastersizer 3000 with Hydro MV.

[0141] C) Ion chromatography (IC) analysis

[0142] The amount of F in the positive electrode active material powder was measured using ion chromatography (IC) with a Dionex ICS-2100 (Thermo Scientific). Before use, 250 mL and 100 mL volumetric flasks were rinsed with a 1:1 mixture of 65 wt% HNO3 and deionized water, and then rinsed with deionized water at least five times. A solvent was prepared by mixing 2 mL of HNO3, 2 mL of H2O2, and 2 mL of deionized water. 0.5 g of the powder sample was dissolved in the mixed solvent. The solution was completely transferred from the container to a 250 mL volumetric flask, and the flask was filled to the 250 mL mark with deionized water. The filled flask was shaken thoroughly to ensure homogeneity of the solution. 9 mL of the solution from the 250 mL flask was transferred to a 100 mL volumetric flask. The 100 mL volumetric flask was filled to the 100 mL mark with deionized water, and the diluted solution was shaken thoroughly to obtain a homogeneous sample solution. Insert 2 mL of sample solution into a 5 mL IC vial using an OnGuard syringe for IC measurement.

[0143] D) Button battery test

[0144] DI) Button cell manufacturing

[0145] To prepare the positive electrode, a slurry containing positive electrode active material powder, a conductor (Super P, Timcal), and a binder (KF#9305, Kureha) (in a weight ratio of 96.5:1.5:2.0) was prepared in a solvent (NMP, Mitsubishi) using a high-speed homogenizer. The homogenized slurry was applied to one side of an aluminum foil using a doctor blade coater with a 170 μm gap. The slurry-coated foil was dried in an oven at 120°C and then pressed using a calendering tool. It was then dried again in a vacuum oven to completely remove any remaining solvent from the electrode film. The coin cell was assembled in an argon-filled glove box. A separator (Celgard 2320) was positioned between the positive electrode and the lithium foil sheet used as the negative electrode. EC / DMC (1:2) containing 1 M LiPF6 was used as the electrolyte and dropped between the separator and the electrode. The coin cell was then completely sealed to prevent electrolyte leakage.

[0146] D2) Test Method

[0147] The testing method is the conventional "constant cutoff voltage" test. The conventional button cell test in this invention follows the schedule shown in Table 2. Each cell is cycled at 25°C using a Toscat-3100 computer-controlled constant current cycling station (from Toyo). A 1C current of 220 mA / g is defined within a metallographic window of 4.3V to 3.0V / Li. The capacity decay rate (QF) is obtained according to the following equation.

[0148]

[0149] Where DQ1 is the discharge capacity of the first cycle, DQ7 is the discharge capacity of the seventh cycle, and DQ34 is the discharge capacity of the thirty-fourth cycle.

[0150] Table 1. Cyclic Plan for Button Battery Testing Methods

[0151]

[0152] E) X-ray photoelectron spectroscopy (XPS) analysis

[0153] In this invention, X-ray photoelectron spectroscopy (XPS) is used to analyze the surface of the positive electrode active material powder particles. In XPS measurements, signals are acquired from the first few nanometers (e.g., 1 nm to 10 nm) of the uppermost portion of the sample (i.e., the surface layer). Therefore, all elements measured by XPS are contained within the surface layer.

[0154] For surface analysis of the positive electrode active material powder particles, XPS measurements were performed using a Thermo K-α+ spectrometer (ThermoScientific). Monochromatic Al Kα radiation (hv = 1486.6 eV) was used with a spot size of 400 μm and a measurement angle of 45°. Wide-range measurements were performed at a pass energy of 200 eV to identify elements present on the surface. The C1s peak with maximum intensity (or intermediate intensity) at a binding energy of 284.8 eV was used as the calibration peak position after data collection. Subsequently, at least 10 precise narrow-range scans were performed at 50 eV for each identified element to determine the accurate surface composition.

[0155] Curve fitting was performed using CasaXPS 2.3.19PR1.0 (Casa Software) with Shirley-type background processing and Scofield sensitivity factor. Fitting parameters were based on Table 2a. The line shape GL(30) is the Gaussian / Lorentz product formula with a 70% Gaussian line and a 30% Lorentz line. LA(α,β,m) is an asymmetric line shape, where α and β define the tail extension of the peak, and m defines the width.

[0156] Table 2a. XPS fitting parameters for Ni2p3, Mn2p3, Co2p3, F1s, W4f, B1s and S2p.

[0157]

[0158] For the Co and W, S peaks, constraints were set for each defined peak according to Table 2b. W5p3 was not quantified.

[0159] Table 2b. XPS Fitting Constraints

[0160]

[0161] The surface contents of F, W, S, and B determined by XPS are expressed as the mole fractions of F, W, S, and B on the particle surface divided by the total contents of Ni, Mn, Co, F, W, B, and S in the surface. They are calculated as follows:

[0162]

[0163]

[0164]

[0165]

[0166]

[0167] F) Carbon analyzer

[0168] The carbon content of the positive electrode active material powder was measured using a Horiba Emia-Expert carbon / sulfur analyzer. One gram of positive electrode active material powder was placed in a ceramic crucible within a high-frequency induction furnace. 1.5 grams of tungsten and 0.3 grams of tin were added to the crucible as promoters. The powder was heated at a programmable temperature, and the gases produced during combustion were then analyzed using an infrared detector. Analysis of CO2 and CO determined the carbon concentration.

[0169] The present invention is further illustrated by the following embodiments:

[0170] Comparative Example 1

[0171] CEX1 was obtained through a solid-state reaction between a lithium source and a transition metal-based source precursor, as follows:

[0172] 1) Coprecipitation: A transition metal-based hydroxide precursor was prepared using a coprecipitation method in a batch reactor. A mixture of nickel manganese cobalt sulfate, sodium hydroxide, and ammonia was fed into the reactor under controlled conditions. The concentrations of the metal salts were varied during precipitation to create a Ni and Mn concentration gradient from the center to the edge of the particles. The total metal composition was Ni. 0.85 Mn 0.10 Co 0.05 As determined by ICP-OES.

[0173] 2) Blending: The precursor prepared in step 1) and LiOH as the lithium source are uniformly blended in an industrial blending device at a lithium to metal M' (Li / M') ratio of 1.005.

[0174] 3) First heating: The blend from step 2) was sintered at 765°C for 10 hours in an oxygen atmosphere. The product was crushed, graded, and sieved. CEX1 has a D50 of 10.5 pm, as determined by PSD method B above. The positive electrode active material CEX1 was determined by CS-EDS method F above to have a Ni and Mn concentration gradient from the edge of the particle to the core, wherein Ni 边缘 / Ni 中心 The ratio = 0.91 and Mn 边缘 / Mn 中心 The ratio is 2.33.

[0175] Example 1

[0176] EX1 was prepared by mixing CEX1 with PVDF powder and WO3 powder at amounts of 1300 ppm F and 4500 ppm W, respectively, followed by heating at 385 °C. EX1 had a D50 of 10.5 μm, as determined by PSD method B above.

[0177] Example 2

[0178] EX2 was prepared by mixing CEX1 with H3BO3, PVDF powder, and WO3 powder in amounts of 500 ppm B, 1300 ppm F, and 4500 ppm W, respectively, followed by heating at 385 °C. EX2 had a D50 of 10.5 μm, as determined by PSD method B above.

[0179] The steps of using PVDF and WO3 in the preparation of EX1 and using PVDF, WO3, and H3BO3 in the preparation of EX2 respectively yielded F. B / F A >1.0, W B / W A >1.0 and B B / B A >1.0, where F B W B and B B Obtained through XPS measurements and F A W A and B A Obtained by ICP-OES measurement.

[0180] Table 3. Overview of the composition and electrochemical properties of CEX1, EX1, and EX2 .

[0181]

[0182] * relative to the molar content of Ni, Mn, Co, F, W and B

[0183] For the embodiments shown in Table 4 above, S B F B B b and W B A value higher than 0 indicates that the element, associated with XPS measurements, is present on the surface of the positive electrode active material. The XPS measurement signal is obtained from the first few nanometers (e.g., 1 nm to 10 nm) of the topmost portion of the sample (i.e., the surface layer). On the other hand, F obtained from ICP-OES measurements... A , BA, and W A Atoms are derived from the entire particle. F B / F A B B / B A and W B / W A A XPS to ICP-OES ratio higher than 1 indicates that F, B, and W elements are mainly present on the surface of the positive electrode active material.

[0184] Table 4 above shows that the positive electrode active materials EX1 and EX2 according to the present invention, which respectively contain F, W and optionally B, have improved properties of reduced carbon content and reduced QF when used in electrochemical cells, compared with those in comparative example CEX1.

[0185] Comparative Example 3.1

[0186] CEX3.1 was obtained through a solid-state reaction between a lithium source and a transition metal-based source precursor, as follows:

[0187] 1) Coprecipitation: In a large continuous stirred tank reactor (CSTR) containing a mixture of nickel manganese cobalt sulfate, sodium hydroxide, and ammonia, a coprecipitation process is used to prepare a product with a metallic composition of Ni. 0.80 Mn 0.10 Co 0.10 Transition metal-based oxide hydroxide precursors.

[0188] 2) Blending: The precursor prepared in step 1) and LiOH as the lithium source are uniformly blended in an industrial blending device at a lithium to metal M' (Li / M') ratio of 1.00.

[0189] 3) First heating: The blend from step 2) is sintered at 805°C for 12 hours in an oxygen atmosphere. The product is crushed, graded and sieved to obtain the first heated powder.

[0190] 4) Wet mixing: The first heated powder from step 3) is mixed with an aluminum sulfate solution prepared by dissolving approximately 3800 ppm Al2(SO4)3 powder in 3.5 wt.% of deionized water relative to the weight of the first heated powder.

[0191] 5) Second heating: The mixture obtained from step 4) is heated at 385°C for 8 hours in an oxygen atmosphere, then ground and sieved to obtain CEX3.1 with a D50 of about 13 μm.

[0192] Comparative Example 3.2

[0193] CEX3.2 was prepared using the same method as CEX3.1, except that a dry mixing step was added before the wet mixing step in step 4). In the dry mixing step, 4000 ppm W from the WO3 powder was mixed with the first heated powder.

[0194] Example 3.1

[0195] EX3.1 was prepared using the same method as CEX3.1, except that a dry mixing step was added before the wet mixing step in step 4). In the dry mixing step, 650 ppm F from the PVDF powder and 4000 ppm W from the WO3 powder were mixed with the first heated powder.

[0196] Example 3.2

[0197] EX3.2 was prepared using the same method as CEX3.1, except that a dry mixing step was added before the wet mixing step in step 4). In the dry mixing step, 650 ppm F from PVDF powder and 6000 ppm W from WO3 powder were mixed with the first heated powder.

[0198] Example 3.3

[0199] EX3.3 was prepared using the same method as CEX3.1, except that a dry mixing step was added before the wet mixing step in step 4). In the dry mixing step, 980 ppm F from PVDF powder and 4000 ppm W from WO3 powder were mixed with the first heated powder.

[0200] The steps of mixing PVDF, WO3, and Al2(SO4)3 compounds in EX3.1, EX3.2, and EX3.3, followed by heat treatment, respectively yielded F. B / F A >1.0, W B / W A >1.0 and S B / S A >1.0, where F B W B and S B Obtained through XPS measurements and F A W A and S A Obtained by ICP-OES measurement.

[0201] Table 4. Overview of the composition and electrochemical properties of CEX3.1, CEX3.2, EX3.1, EX3.2 and EX3.3

[0202]

[0203] * Molar content relative to Ni, Mn, Co, F, W, B and S

[0204] In all embodiments, F B S B B b and W BA value higher than 0 indicates that the element, associated with XPS measurements, is present on the surface of the positive electrode active material. The XPS measurement signal is obtained from the first few nanometers (e.g., 1 nm to 10 nm) of the topmost portion of the sample (i.e., the surface layer). On the other hand, F obtained from ICP-OES measurements... A S A B A and W A Atoms are derived from the entire particle. F B / F A S B / S A B B / B A and W B / W A A XPS to ICP-OES ratio higher than 1 indicates that F, S, B, and W elements are mainly present on the surface of the positive electrode active material.

Claims

1. A positive electrode active material for a lithium-ion rechargeable battery, wherein the positive electrode active material comprises Li, M', and oxygen, wherein M' comprises: - Relative to Ni with M' content x between 60.0 mol% and 95.0 mol%; - Co with a content of M' of y, where 0 ≤ y ≤ 40.0 mol% - Mn with a content of z relative to M', where 0 ≤ z ≤ 70.0 mol% - D relative to M' content of a, where 0 ≤ a ≤ 2.0 mol%, and D includes elements other than Li, O, Ni, Co, Mn, F, W, S and B; - F with a content of b relative to M', where b>0; - W with a content of c relative to M', where c>0; - S with a content of M' of d, where 0 ≤ d ≤ 4.0 mol% - For B with a content of e relative to M', where 0 ≤ e ≤ 4.0 mol%; and, - Where x, y, z, a, c, d, and e are measured by inductively coupled plasma optical emission spectroscopy. - Where b is measured by ion chromatography. - where x+y+z+a+b+c+d+e is 100.0 mol%. The positive electrode active material thereon has the following definition: F content F A and defined as W content A , The positive electrode active material has an F content of F B and W content W B , where F B and W B The F was determined by X-ray photoelectron spectroscopy analysis. B and W B Each is expressed as a mole fraction relative to the sum of the mole fractions of Co, Mn, Ni, F, W, S, and B as measured by XPS analysis. Where the ratio F B / F A > 1.0, Where the ratio W B / W A > 1.

0.

2. The positive electrode active material according to claim 1, wherein d > 0, wherein the positive electrode active material has a defined... S content A , The positive electrode active material has an S content determined by XPS analysis. B S B Mole fraction expressed as a ratio to the sum of the mole fractions of Co, Mn, Ni, F, W, S, and B as measured by XPS analysis. Where the ratio S B / S A > 1.

0.

3. The positive electrode active material according to claim 1 or 2, wherein e>0, and wherein the positive electrode active material has a defined... B content A , The positive electrode active material has a B content determined by XPS analysis. B B B Mole fraction expressed as a ratio to the sum of the mole fractions of Co, Mn, Ni, F, W, S, and B as measured by XPS analysis. Where ratio B B / B A > 1.

0.

4. The positive electrode active material according to claim 3, wherein the ratio B B / B A > 2.

0.

5. The positive electrode active material according to claim 1 or 2, wherein the ratio F B / F A > 2.

0.

6. The positive electrode active material according to claim 1 or 2, wherein the ratio W B / W A > 2.

0.

7. The positive electrode active material according to claim 1 or 2, wherein D comprises at least one element selected from the following: Al, Ba, Ca, Cr, Fe, Mg, Mo, Nb, Si, Sr, Ti, Y, V, Zn, and Zr.

8. The positive electrode active material according to claim 1 or 2, wherein D has a content a between 0.01 mol% and 2.0 mol% relative to M'.

9. A method for manufacturing a positive electrode active material according to any one of claims 1 to 8, wherein the method comprises the following sequential steps: Step 1) Mix lithium transition metal oxide with an F-containing compound and a W-containing compound to obtain a mixture; and Step 2) Heat the mixture in an oxidizing atmosphere at a temperature between 250°C and less than 500°C to obtain the positive electrode active material.

10. The method according to claim 9, wherein the F-containing compound is PVDF.

11. The method according to claim 9, wherein the W-containing compound is WO3.

12. The method according to any one of claims 9 to 11, wherein in step 1), the B-containing compound is added together with the F- and W-containing compounds.

13. The method according to claim 12, wherein the B-containing compound is H3BO3.

14. The method according to any one of claims 9 to 11, wherein the method further comprises an additional step between step 1 and step 2, wherein the additional step is to combine the mixture from step 1) with a solution containing the S-containing compound.

15. The method according to claim 14, wherein the S-containing compound used is Al2(SO4)3.

16. A battery comprising a positive electrode active material according to any one of claims 1 to 8.

17. Use of the battery according to claim 16 in a portable computer, mobile phone, electric vehicle or energy storage system.

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