Positive electrode active materials for rechargeable lithium-ion batteries

Abstract

The present invention relates to a positive electrode active material for a battery, which contains Li, M', and oxygen, where M' contains: Ni with a content a between 60.0 mol% and 75.0 mol%; Co with a content x between 0.0 mol% and 20.0 mol%; Mn with a content y between 0.0 mol% and 35.0 mol%; a dopant D with a content z between 0.0 mol% and 2.0 mol%; Al, B, and W with a total content c between 0.1 mol% and 5.0 mol%, where the active material has an Al content Al A 、a B content B A and a W content W A , where a, x, y, z, c, Al A 、B A and W A are measured by ICP, where Al A 、B A and W A , where when measured by XPS analysis, the positive electrode active material shows an average Al fraction Al B , an average B fraction B B and an average W fraction W B , where A Bl / Al A 、B B / B A and W B / W A are all greater than 1.0, and where the positive electrode active material is single crystal powder.

Description

Technical Field

[0001] The present invention relates to a positive electrode active material for a lithium ion rechargeable battery. More specifically, the present invention relates to a granular positive electrode active material containing Al, B and W elements; a battery containing the granular positive electrode active material containing Al and B elements; and use of the positive electrode active material in a battery for any one of a portable computer, a tablet computer, a mobile phone, an electric vehicle and an energy storage system. Background Art

[0002] The present invention relates to a single crystalline positive electrode active material powder for lithium ion rechargeable batteries (LIBs), comprising the elements Al, B and W.

[0003] Positive electrode active materials containing Al and B elements are known, for example from US 2016 / 336595. Document US2016 / 336595 discloses a positive electrode active material powder comprising a mixture of lithium nickel manganese cobalt oxide (NMC), Al(OH)3 powder and B2O3 powder, which is then heated at 400°C. The Ni content in NMC is about 60 mol%. However, the positive electrode active material according to US 2016 / 336595 has a low initial discharge capacity (DQ1), a high irreversible capacity (IRRQ) and a high internal resistance (DCR at SOC50%).

[0004] It is therefore an object of the present invention to provide a positive electrode active material having improved electrochemical properties, such as one or more of the following: DQ1, IRRQ, and DCR at SOC50%. Summary of the invention

[0005] This object is achieved by providing a positive electrode active material for a lithium ion rechargeable battery, wherein the positive electrode active material is a powder, wherein the positive electrode active material comprises Li, M' and oxygen, wherein M' comprises:

[0006] - Ni, whose content a is between 60.0 mol % and 75.0 mol % relative to M',

[0007] - Co, whose content x is between 0.0 mol % and 20.0 mol % relative to M',

[0008] - Mn, whose content y is between 0.0 mol % and 35.0 mol % relative to M',

[0009] - D, whose content z is between 0.0 mol % and 2.0 mol % relative to M', wherein D comprises at least one element selected from Ba, Ca, Cr, Fe, Mg, Mo, Nb, S, Si, Sr, Ti, Y, V, Zn and Zr, and

[0010] - Al and B and W, wherein the total content c of Al and B and W is between 0.1 mol % and 5.0 mol % relative to M',

[0011] - where a, x, y, z and c are measured by ICP,

[0012] - wherein a+x+y+c+z is 100.0 mol%,

[0013] - wherein the positive electrode active material has an Al content Al A , B content A and W content A , where Al A , B A and W A The Al A , B A and W A Expressed as the mole fraction compared to the sum of a and x and y,

[0014] - wherein the powder exhibits an average Al fraction Al when measured by XPS analysis B , average B score B B and the average W score W B , where Al B , B B and W B Expressed as the mole fraction compared to the sum of the fractions of Co, Mn and Ni measured by XPS analysis,

[0015] - Among them, the ratio Al B / Al A >1.0,

[0016] - where ratio B B / B A >1.0,

[0017] - where the ratio W B / W A >1.0, and

[0018] The powder is a single crystal powder.

[0019] It is indeed observed that higher DQ1 and lower DCR at SOC50% are achieved using the positive electrode active material according to the present invention, as illustrated by the examples and supported by the results provided in Tables 3 and 4.

[0020] Furthermore, the present invention provides an electrochemical cell comprising the positive electrode active material according to the first aspect of the invention and the use of the positive electrode active material according to the first aspect of the invention in a cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] By way of further instruction, the accompanying drawings are included to better understand the teachings of the present invention. The drawings are intended to aid in describing the present invention and are not intended to be limitations of the presently disclosed invention.

[0022] Figure 1a shows a scanning electron microscope (SEM) image of a positive electrode active material powder having a single crystal morphology according to EX1; Figure 1b A scanning electron microscope (SEM) image of a positive electrode active material powder having a single crystal morphology according to EX2 is shown.

[0023] Figure 2a shows a comparison of discharge DCR (in %) of CEX1.1, CEX1.2 and EX1 at -10°C according to the state of charge; Figure 2b A comparison of the discharge DCR at -10°C for CEX2.1, CEX2.2 and EX2 is shown (in %) according to the state of charge.

[0024] Figure 3a The XPS spectrum of EX2 measured in the range of 66 to 80 eV is shown, which contains Al2p and Ni3p peaks; Figure 3b Shown is the XPS spectrum of EX2 measured in the range of 187 to 197 eV, which contains the B1s peak. DETAILED DESCRIPTION

[0025] Unless otherwise defined, all terms (including technical and scientific terms) used in disclosing the present invention have the meanings commonly understood by those of ordinary skill in the art to which the present invention belongs. By way of further guidance, term definitions are included to better understand the teachings of the present invention.

[0026] As used herein, the following terms have the following meanings:

[0027] As used in this document, the term "ppm" means parts per million on a mass basis.

[0028] As used herein, "about" in relation to a measurable value such as a parameter, amount, time duration, etc., is intended to encompass + / -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 and variations from the specified value, within which such variations are suitable for performing in the disclosed invention. However, it should be understood that the value to which the modifier "about" refers is itself also specifically disclosed.

[0029] Numerical ranges recited by endpoints include all numbers and fractions subsumed within that range, as well as the recited endpoints. All percentages should be understood to be weight percentages abbreviated as "wt %" unless otherwise defined or unless a different meaning is apparent to one skilled in the art from its use and the context in which it is used.

[0030] The term "median particle size D50" as defined herein may be used interchangeably with the term "D50" or "d50" or "median particle size" or "median particle size (d50 or D50)". D50 is defined herein as the particle size at 50% of the cumulative volume % distribution. D50 is typically determined by laser diffraction particle size analysis.

[0031] The term "atomic %" as defined herein is equivalent to the term "atomic percent" and means atomic percent. The term "atomic %" in a given element expression of concentration means what percentage of all atoms in the compound of interest are atoms of the element. The term "atomic %" is equivalent to the term "mole %" or "molar percent".

[0032] Positive electrode active material is defined as a material that is electrochemically active in the positive electrode. By active material, it must be understood that the material is capable of capturing and releasing lithium ions when subjected to a voltage change over a predetermined period of time.

[0033] Positive electrode active material

[0034] In a first aspect, the present invention provides a positive electrode active material for a lithium ion rechargeable battery, wherein the positive electrode active material is a powder, wherein the positive electrode active material comprises Li, M' and oxygen, wherein M' comprises:

[0035] - Ni, whose content a is between 60.0 mol % and 75.0 mol % relative to M',

[0036] - Co, whose content x is between 0.0 mol % and 20.0 mol % relative to M',

[0037] - Mn, whose content y is between 0.0 mol % and 35.0 mol % relative to M',

[0038] - D, whose content z is between 0.0 mol % and 2.0 mol % relative to M', wherein D comprises at least one element selected from Ba, Ca, Cr, Fe, Mg, Mo, Nb, S, Si, Sr, Ti, Y, V, Zn and Zr, and

[0039] - Al and B and W, wherein the total content c of Al and B and W is between 0.1 mol % and 5.0 mol % relative to M',

[0040] - where a, x, y, z and c are measured by ICP,

[0041] - wherein a+x+y+c+z is 100.0 mol%,

[0042] - wherein the positive electrode active material has an Al content Al A , B content A and W content A , where Al A , B A and W A The Al A , B A and W A Expressed as the mole fraction compared to the sum of a and x and y,

[0043] - wherein the powder exhibits an average Al fraction Al when measured by XPS analysis B , average B score B B and the average W score W B , where Al B , B B and W B Expressed as the mole fraction compared to the sum of the fractions of Co, Mn and Ni measured by XPS analysis,

[0044] - Among them, the ratio Al B / Al A >1.0, where ratio B B / B A >1.0, and where the ratio W B / W A >1.0, and

[0045] The powder is a single crystal powder.

[0046] Single crystal powders are considered powders in which the SEM image has a thickness of at least 45 μm x at least 60 μm (i.e. at least 2700 μm). 2 ), preferably at least 100 μm×100 μm (ie, at least 10,000 μm 2 ) field of view, 80% or more of the particles have a single crystal morphology.

[0047] A particle is considered to have a single crystalline morphology if it consists of only one type of grain, or a very low number of at most five constituent grains, as observed by SEM or TEM. For example, a particle having a single crystalline morphology is shown in Figure 1a and Figure 1b In the figure, they are the SEM images of EX1 and EX2 respectively.

[0048] For the purpose of determining the single crystal morphology of the particles, grains having a maximum linear dimension observed by SEM less than 20% of the median particle size D50 of the powder determined by laser diffraction are disregarded. This avoids particles which are essentially single crystals but may have several very small other grains deposited thereon from being inadvertently considered not to have single crystal morphology.

[0049] When used in an electrochemical cell, the positive electrode active material for a lithium ion rechargeable battery according to the present invention does have improved electrochemical properties, allowing higher DQ1, lower IRRQ and lower DCR at SOC50% to be achieved. This is shown by the examples and the results are provided in Table 3.

[0050] XPS analysis provides the atomic content of elements in the uppermost layer of the positive electrode active material particles with a penetration depth of about 10 nm from the outer boundary of the particle. The outer boundary of the particle is also referred to as the "surface".

[0051] The composition of the positive electrode active material particles can be expressed in the general formula Li1+b(Ni a Mn y CO x A c D z ) 1-b O2 is represented by the indices a, x, y, z, b, c and d. ICP analysis provides the weight fractions of the elements in the positive electrode active material particles.

[0052] Preferably, the nickel content, a, of the positive electrode active material is at least 62.0 mol %, and more preferably at least 64.0 mol %, relative to M', as measured by ICP.

[0053] Preferably, the cobalt content x of the positive electrode active material is at least 0.0 mol%, 1.0 mol%, at least 2.0 mol%, or even at least 3.0 mol% relative to M', as measured by ICP. The present invention provides a positive electrode active material having a cobalt content x relative to M' of 0.0, 3.0, 5.0, 7.0, 9.0 or 10.0 mol%, or any value therebetween, as measured by ICP. In a preferred embodiment, the cobalt content x of the positive electrode active material is between 0.0 mol% and 2.0 mol% relative to M', as measured by ICP.

[0054] Preferably, the manganese content y of the positive electrode active material is at most 35.0 mol%, preferably at most 30.0 mol%, relative to M', as determined by ICP. Preferably, the manganese content y of the positive electrode active material is at least 10.0 mol%, at least 12.0 mol%, or even at least 15.0 mol%, relative to M', as determined by ICP. The present invention provides a positive electrode active material having a manganese content y of 15.0, 20.0, 25.0 or 30.0 mol%, relative to M', or any value therebetween, as determined by ICP.

[0055] Preferably, the present invention provides a positive electrode active material, wherein the molar ratio of lithium to the total molar amount of nickel, manganese and / or cobalt is 0.95≤Li:Me≤1.10, wherein Me is the total molar fraction of Ni, Mn and / or Co.

[0056] Preferably, the present invention provides a positive electrode active material according to the first aspect of the present invention, wherein the particles contain Al as well as B and W. The total content of Al, B and W relative to M' measured by ICP is preferably between 0.1 and 5.0 mol %, and more preferably between 0.4 and 2.0 mol %.

[0057] Preferably, Al A Between 0.025 and 2.0 mol %, expressed as mole fraction compared to the sum of a and x and y as measured by ICP.

[0058] Preferably, B A Between 0.025 and 2.0 mol %, expressed as mole fraction compared to the sum of a and x and y as measured by ICP.

[0059] Preferably, W A Between 0.025 and 2.0 mol %, expressed as mole fraction compared to the sum of a and x and y as measured by ICP.

[0060] Preferably, B A is at least 0.0015, in other words, at least 0.15 mol %, and more preferably, B A is at least 0.0018, in other words, at least 0.18 mol %, expressed as a mole fraction compared to the sum of a and x and y as measured by ICP.

[0061] Preferably, Al A is at most 0.0080, in other words, at most 0.8 mol %, expressed as a mole fraction compared to the sum of a and x and y measured by ICP.

[0062] Preferably, W ALess than 0.002, in other words, less than 0.2 mol %, expressed as a mole fraction compared to the sum of a and x and y measured by ICP.

[0063] Preferably, the ratio A1 B / Al A >10, more preferably Al B / Al A >150.

[0064] In a preferred embodiment, the ratio A1 B / Al A <800.

[0065] Preferably, the ratio B B / B A >10, more preferably, ratio B B / B A >30, and most preferably, the ratio B B / B A >115.

[0066] In a preferred embodiment, the ratio B B / B A <500.

[0067] Preferably, the ratio W B / W A >10, more preferably, the ratio W B / W A >50, and most preferably, the ratio W B / W A >115.

[0068] In a preferred embodiment, the ratio W B / W A <500.

[0069] Preferably, the positive electrode active material has a median particle size (d50 or d50) of 2.0 μm to 9.0 μm, as determined by laser diffraction. The median particle size (d50 or d50) can be measured with a Malvern Mastersizer 3000. Preferably, the median particle size is between 2.0 μm and 8.0 μm, more preferably between 3.0 μm and 7.0 μm, and most preferably about 4.0 μm.

[0070] Indeed, it is observed that the positive electrode active material according to the invention achieves the objectives of providing higher DQ1, lower IRRQ and lower DCR at SOC50% when used in an electrochemical cell, as shown by the examples and supported by the results provided in Tables 3 and 4.

[0071] DQ1 and IRRQ are determined by the coin cell test procedure in the 4.4-3.0V / Li metal window range using a 1C current definition of 160mA / g, and the DCR at SOC50% is determined by the full cell test procedure at -10°C using a 1C current definition of 2000mAh / g. The test procedure is further described in §1.3 and is incorporated herein by reference.

[0072] Preferably, the positive electrode active material according to the first aspect of the present invention comprises LiAlO 2 , Al 2 O 3 and a Li—B—O compound, as identified by XPS.

[0073] Electrochemical Cells

[0074] In a second aspect, the present invention provides a battery cell comprising a positive electrode active material according to the first aspect of the present invention.

[0075] In a third aspect, the present invention provides use of the positive electrode active material according to the first aspect of the present invention in a battery for any one of a portable computer, a tablet computer, a mobile phone, an electric vehicle, and an energy storage system.

[0076] Example

[0077] The following examples are intended to further illustrate the present invention but are not intended to limit the scope of the present invention.

[0078] 1. Description of the analytical method

[0079] 1.1. Inductively coupled plasma

[0080] The composition of the positive electrode active material powder was measured by inductively coupled plasma (ICP) method using 720ICP-OES (Agilent Technologies, https: / / www.agilent.com / cs / library / brochures / 5990-6497EN%20720-725_ICP-OES_LR.pdf). 1 gram of powder sample was dissolved in 50 mL of high purity hydrochloric acid (at least 37% by weight of HCl relative to the total weight of the solution) in a conical flask. The bottle can be covered with a watch glass and heated on a hot plate at 380°C until the powder is completely dissolved. After cooling to room temperature, the solution in the conical flask was poured into the first 250 mL volumetric flask.

[0081] After that, fill the first volumetric flask with deionized water until the 250mL mark, and then perform a complete homogenization process (1st dilution). Take out an appropriate amount of solution from the first volumetric flask by pipette and transfer it to the second 250mL volumetric flask for the second dilution. At this time, fill the second volumetric flask with internal standard elements and 10% hydrochloric acid until the 250mL mark, and then homogenize. Finally, the solution is used for ICP measurement.

[0082] 1.2. Particle size distribution

[0083] After each of the powder samples was dispersed in an aqueous medium, the particle size distribution (PSD) of the positive electrode active material powder was measured by laser diffraction particle size analysis using a Malvern Mastersizer 3000 with a Hydro MV wet dispersion attachment (https: / / www.malvernpanalytical.com / en / products / product-range / mastersizer-range / mastersizer-3000#overview). In order to improve the dispersibility of the powder, sufficient ultrasonic irradiation and stirring were applied, and an appropriate surfactant was introduced. D50 is defined as the particle size at 50% of the cumulative volume % distribution obtained from the Malvern Mastersizer 3000 measurement with Hydro MV.

[0084] 1.3. Button battery test

[0085] 1.3.1. Button cell preparation

[0086] 1.3.1.1.CEX1.1, CEX1.2, EXI, CEX2.1, CEX2.2 and EX2

[0087] To prepare the positive electrode, a slurry containing positive electrode active material powder, conductor (Super P, Timcal), binder (KF#9305, Kureha) (in a 90:5:5 formulation by weight) was prepared by a high-speed homogenizer in a solvent (NMP, Mitsubishi). The homogenized slurry was applied to one side of an aluminum foil using a doctor blade coater with a gap of 230 μm. The slurry-coated foil was dried in an oven at 120°C and then pressed using a calendaring tool with a gap of 40 μm.

[0088] Then it was dried again in a vacuum oven to completely remove the remaining solvent in the electrode film. The button cell was assembled in a glove box filled with argon. The separator (Celgard 2320) was located between the positive electrode and the lithium foil used as the negative electrode. EC / DMC (1:2) containing 1M LiPF6 was used as an electrolyte and was dripped between the separator and the electrode. Then, the button cell was completely sealed to prevent electrolyte leakage.

[0089] 1.3.1.2.EX3.1 and EX3.2

[0090] To prepare the positive electrode, a slurry containing positive electrode active material powder, conductor (Super P, Timcal), binder (KF#9305, Kureha) (in a formula of 96.5:1.5:2.0 by weight) was prepared by a high-speed homogenizer in a solvent (NMP, Mitsubishi). The homogenized slurry was applied to one side of an aluminum foil using a doctor blade coater with a gap of 170 μm. The slurry-coated foil was dried in an oven at 120°C and then pressed using a hydraulic calendaring tool at a pressure of 530 bar.

[0091] Then it was dried again in a vacuum oven to completely remove the remaining solvent in the electrode film. The button cell was assembled in a glove box filled with argon. The separator (Celgard 2320) was located between the positive electrode and the lithium foil used as the negative electrode. EC / DMC (1:2) containing 1M LiPF6 was used as an electrolyte and was dripped between the separator and the electrode. Then, the button cell was completely sealed to prevent electrolyte leakage.

[0092] 1.3.2.Testing methods

[0093] The test method was a conventional "constant cutoff voltage" test. Conventional button cell testing in the present invention followed the schedule shown in Table 1. Each cell was cycled at 25°C using a Toscat-3100 computer controlled constant current cycling station (available from Toyo, http: / / www.toyosystem.com / image / menu3 / toscat / TOSCAT-3100.pdf).

[0094] The 1C current definition is 160mAh / g. The initial charge capacity (CQ1) and discharge capacity (DQ1) were measured in constant current mode (CC) at a C rate of 0.1C in the 4.3V to 3.0V / Li metal window range.

[0095] The irreversible capacity IRRQ is expressed in % as follows:

[0096] IRRQ(%)=100%*(CQ1-DQ1) / CQ1

[0097] Table 1. Cycle schedule for coin cell battery test method

[0098]

[0099] Full battery test

[0100] 1.3.3. Full cell preparation

[0101] A 2000 mAh (flexible) pouch cell was prepared as follows: a positive electrode active material powder, a conductor (Super-P, Timcal (Imerys Graphite & Carbon)), graphite (KS6, Timrex (Imerys Graphite & Carbon), http: / / www.imerys-graphite-and-carbon.com / wordpress / wp-app / uploads / 2014 / 04 / Powder-Metallurgy.pdf) as a conductive agent, and polyvinylidene fluoride (PVDF 1710, Kureha, https: / / www.kureha.co.jp / en / business / material / pdf / KFpolymer_BD_en.pdf) as a binder were added to N-methyl-2-pyrrolidone (NMP) as a dispersion medium so that the weight ratio of the positive electrode active material powder, the conductive agent, and the binder was set to 96 / 1 / 1 / 2. Thereafter, the mixture was kneaded to prepare a mixture slurry. The resulting mixture slurry was then applied to both sides of a current collector made of 20 μm thick aluminum foil. The width of the application area was 88.5 mm and the length was 425 mm. The typical loading weight of the positive electrode active material was about 16.9 ± 0.2 mg / cm 2 The electrode was then dried and rolled to 3.25 ± 0.05 g / cm using a pressure of 4.5 MPa. 3 In addition, an aluminum plate used as a cathode current collector is arc welded to the end of the positive electrode.

[0102] A commercially available negative electrode was used. Briefly, a mixture of graphite, carbon, sodium carboxymethyl cellulose (CMC), and styrene butadiene rubber (SBR) in a weight ratio of 95 / 1 / 1.5 / 2.5 was applied to both sides of an 8 μm thick copper foil. A nickel plate used as a negative electrode current collector was arc welded to the end of the negative electrode. The typical loading weight of the negative electrode active material was 10 ± 0.5 mg / cm 2 .

[0103] The non-aqueous electrolyte was obtained by dissolving lithium hexafluorophosphate (LiPF6) salt at a concentration of 1.2 mol / L in a mixed solvent of ethylene carbonate (EC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC) in a volume ratio of 1:1:1 and 1% by volume of vinylene carbonate (VC). An additive containing 1% by weight of LiPO2F2 was introduced into the above electrolyte.

[0104] To obtain a spirally wound electrode assembly, a positive electrode sheet, a negative electrode sheet, and a separator sheet made of a 13 μm thick microporous polymer film (Asahi) sandwiched therebetween were spirally wound using a winding mandrel. The assembly and the electrolyte were then placed in an aluminum laminate bag in an air-dried room with a dew point of -50°C to prepare a flat pouch lithium rechargeable battery. The design capacity of the rechargeable battery is 2000 mAh when charged to 4.25 V. The nonaqueous electrolyte solution was immersed for 8 hours at room temperature. The battery was precharged to 15% of its expected full capacity and aged at room temperature for one day. The battery was then degassed and the aluminum bag was sealed. The battery was prepared for use as follows: In CC mode (constant current), the battery was charged to 4.25 V using a current of 0.2C (where 1C = 2000 mA), then charged in CV mode (constant voltage) until a cutoff current of C / 20 was reached, and then discharged at a rate of 0.2C in CC mode to a cutoff voltage of 2.7 V.

[0105] 1.3.4. Full battery test

[0106] 1.3.4.1. Full battery cycle life test

[0107] The prepared full-cell batteries were charged and discharged multiple times at 25 °C under the following conditions to determine their charge-discharge cycle performance:

[0108] a. First charge at 1C rate in CC mode until 4.25V, then charge in CV mode until C / 20 is reached,

[0109] b. Then let the battery rest for 10 minutes.

[0110] c. Perform the first discharge at 1C rate in CC mode, down to 2.7V,

[0111] d. Then let the battery rest for 10 minutes.

[0112] e. Perform charge and discharge cycles until the remaining capacity of the battery reaches about 80%. Every 100 cycles, discharge at a rate of 0.1C in CC mode to 2.7V.

[0113] 1.3.4.2. Discharge DC resistance

[0114] The internal resistance or DC resistance (DCR) is measured by applying a suitable pulse test to the battery.

[0115] a. First charge at 1C rate in CC mode until 4.25V, then charge in CV mode until C / 20 is reached,

[0116] b. Then let the battery rest for 10 minutes.

[0117] c. Perform the first discharge at 1C rate in CC mode, down to 90% SOC,

[0118] d. Then let the battery rest for 20 minutes.

[0119] e. The second discharge was carried out at a rate of 1.5C for 10 seconds, followed by a rest period of 40 seconds.

[0120] f. The second charge was performed at a rate of 1.5C for 10 seconds, followed by a 1 minute rest.

[0121] g. Repeat steps b to f at 10% intervals until SOC 10% is reached. Measure the DCR at each SOC level and compare the DCR at SOC 50%.

[0122] 1.4. X-ray Photoelectron Spectroscopy (XPS)

[0123] In the present invention, X-ray photoelectron spectroscopy (XPS) is used to analyze the surface of the positive electrode active material powder particles. In XPS measurement, signals are collected from the first few nanometers (e.g., 1nm to 10nm) of the uppermost part of the sample (i.e., the surface layer). Therefore, all elements measured by XPS are contained in the surface layer.

[0124] For the surface analysis of the positive electrode active material powder particles, XPS measurement was performed using a Thermo K-α+ spectrometer (Thermo Scientific, https: / / www.thermofisher.com / order / catalog / product / IQLAADGAAFFACVMAHV).

[0125] Monochromatic Al Kα radiation (hu=1486.6 eV) was used with a spot size of 400 μm and a measurement angle of 45°. A wide-range measurement scan was performed at 200 eV pass energy to identify the elements present on the surface. The C1s peak with maximum intensity (or center) at a binding energy of 284.8 eV was used as the calibration peak position after data collection. At least 10 accurate narrow-range scans were then performed at 50 eV for each identified element to determine the exact surface composition.

[0126] The curves were fitted using CasaXPS 2.3.19PR1.0 (Casa Software, http: / / www.casaxps.com / ) with Shirley-type background processing and Scofield sensitivity factors. The fitting parameters were according to Table 2a. The line shape GL (30) is a Gaussian / Lorentzian product formula with 70% Gaussian lines and 30% Lorentzian lines. LA (α, β, m) is an asymmetric line shape, where a and β define the tail extension of the peak, and m defines the width.

[0127] Table 2a. XPS fitting parameters of Ni2p3, Mn2p3, Co2p3, Al2p and F1s .

[0128]

[0129] For Al, Co and W peaks, constraints were set for each defined peak according to Table 2b. Ni3p and W5p3 were not quantified.

[0130] Table 2b. XPS fitting constraints for Al2p peak fitting

[0131]

[0132] Table 2c shows a reference for the maximum peak intensity position ranges of Al and B related compounds.

[0133] Table 2c. XPS peak references

[0134]

[0135] *The binding energy range of Al peak 1 varies with the amount of Al doped in the structure.

[0136] The surface contents of Al, B, and W determined by XPS are expressed as the molar fractions of Al, B, and W in the particle surface layer divided by the total contents of Ni, Mn, and Co in the surface layer. They are calculated as follows:

[0137] Al fraction = Al B =Al (atomic %) / (Ni (atomic %) + Mn (atomic %) + Co (atomic %))

[0138] B's score = B B =B (atomic %) / (Ni (atomic %) + Mn (atomic %) + Co (atomic %))

[0139] Fraction of W = W B =W(atomic%) / (Ni(atomic%)+Mn(atomic%)+Co(atomic%)).

[0140] 2. Examples and Comparative Examples

[0141] Comparative Example 1

[0142] The single crystalline positive electrode active material labeled CEX1.1 was prepared according to the following steps:

[0143] Step 1) Preparation of transition metal oxide hydroxide precursors: A metal composition of Ni is prepared by a coprecipitation process in a large continuous stirred tank reactor (CSTR) with mixed nickel manganese cobalt sulfate, sodium hydroxide and ammonia. 0.68 Mn 0.27 Co 0.05 Nickel-based transition metal oxidic hydroxide powder (TMH1).

[0144] Step 2) First Mixing: TMH1 prepared in step 1) was mixed with LiOH in an industrial blender so as to obtain a first mixture with a lithium to metal (Ni, Co and Mn) ratio of 1.03.

[0145] Step 3) First calcination: The first mixture obtained in step 2) is calcined at 925°C for 10 hours in an oxidizing atmosphere to obtain a first calcined powder, followed by air jet milling and sieving.

[0146] Step 4) Second mixing: The ground powder obtained from step 3) is mixed in an industrial blender with 500 ppm of Al from alumina powder (Al2O3), 2.0 mol% of Co from CO3O4 powder, 0.25 mol% of Zr from ZrO2 powder, and 2.0 mol% of Li from LiOH, each relative to the total molar content of Ni, Mn and Co in the ground powder, so as to obtain a second mixture.

[0147] Step 5) Second calcination: The second mixture obtained in step 4) is calcined at 775° C. for 12 hours in an oxidizing atmosphere to obtain a second calcined body.

[0148] Step 6) Grinding and sieving: The second calcined body obtained from step 5) was ground together with alumina powder and sieved. The sieved powder containing 500 ppm Al had a median particle size of 4 μm as determined by laser diffraction measured with a Malvern Mastersizer 3000.

[0149] Step 7) Third mixing: The sieved powder obtained in step 6) was mixed with H3BO3 powder in an industrial blender so as to obtain a third mixture containing 500 ppm of B.

[0150] Step 8) Third calcination: The third mixture obtained from step 7) was calcined at 375°C for 7 hours in an oxidizing atmosphere, then ground and sieved with 500 ppm of Al from alumina powder relative to the total weight of the mixture obtained from step 5). The product of this step was a ground powder labeled CEX1.1.

[0151] Due to the air jet milling in step 3), CEX1.1 is a single crystalline powder.

[0152] CEX1.1 is based on document US 2016 / 336595.

[0153] CEX1.2 was prepared according to the same method as CEX1.1, except that more H3BO3 powder was added in step 7) to obtain a third mixture containing 1000 ppm B.

[0154] Example 1

[0155] EXI was prepared according to the same method as CEX1.1, except that WO3 powder was added together with H3BO3 powder in step 7) so as to obtain a third mixture containing 500 ppm B and 2000 ppm W.

[0156] Comparative Example 2

[0157] The single crystalline positive electrode active material labeled CEX2.1 was prepared according to the following steps:

[0158] Step 1) Preparation of transition metal oxide hydroxide precursors: A metal composition of Ni is prepared by a coprecipitation process in a large continuous stirred tank reactor (CSTR) with mixed nickel manganese cobalt sulfate, sodium hydroxide and ammonia. 0.73 Mn 0.20 Co 0.07 Nickel-based transition metal oxide hydroxide powder (TMH2).

[0159] Step 2) First Mixing: TMH2 prepared in step 1) is mixed with LiOH in an industrial blender so as to obtain a first mixture having a lithium to metal (Ni, Co and Mn) ratio of 1.00.

[0160] Step 3) First calcination: The first mixture obtained in step 2) is calcined at 915° C. for 11 hours in an oxidizing atmosphere to obtain a first calcined powder.

[0161] Step 4) Wet bead milling: The first calcined powder obtained in step 3) was bead milled in a solution containing 0.5 mol% Co relative to the total molar content of Ni, Mn and Co in the first calcined powder, followed by a pulverizing and sieving process to obtain a ground powder. The weight ratio of bead milled solid to solution was 65%.

[0162] Step 5) Second mixing: The ground powder obtained from step 4) is mixed in an industrial blender with 2.0 mol % of Co from CO3O4 powder, 0.25 mol % of Zr from ZrO2 powder, and 8.5 mol % of Li powder from LiOH, each relative to the total molar content of Ni, Mn and Co in the ground powder, so as to obtain a second mixture.

[0163] Step 6) Second calcination: The second mixture obtained in step 5) is calcined at 775° C. for 12 hours in an oxidizing atmosphere to obtain a second calcined body.

[0164] Step 7) Grinding and sieving: The second calcined body obtained from step 6) was ground together with alumina powder and sieved to obtain sieved powder. The sieved powder containing 500 ppm Al had a median particle size of 3.5 μm as determined by laser diffraction measured with a Malvern Mastersizer 3000.

[0165] Step 8) Third mixing: The sieved powder obtained in step 7) was mixed with H3BO3 powder in an industrial blender so as to obtain a third mixture containing 500 ppm of B.

[0166] Step 9) Third calcination: The third mixture obtained from step 8) was calcined at 375°C for 7 hours in an oxidizing atmosphere, and then ground and sieved with 500 ppm of Al from alumina powder relative to the total weight of the mixture obtained from step 9). The product of this step is a ground powder labeled CEX2.1.

[0167] Due to the wet grinding in step 4), CEX4.1 is a single crystalline powder.

[0168] CEX2.2 was prepared according to the same method as CEX2.1, except that more H3BO3 powder was added in step 8 to obtain a third mixture containing 1000 ppm B.

[0169] Example 2

[0170] EX2 was prepared according to the same method as CEX2.1, except that WO3 powder was added together with H3BO3 powder in step 8) so as to obtain a third mixture containing 500 ppm B and 2000 ppm W.

[0171] Comparative Example 3

[0172] The single crystalline positive electrode active material, labeled CEX3, was prepared according to the following steps:

[0173] Step 1) Preparation of transition metal oxide hydroxide precursors: A metal composition of Ni is prepared by a coprecipitation process in a large continuous stirred tank reactor (CSTR) with mixed nickel manganese cobalt sulfate, sodium hydroxide and ammonia. 0.70 Mn 0.30 Nickel-based transition metal oxide hydroxide powder (TMH3). Step 2) First mixing: TMH2 prepared by step 1) is mixed with LiOH and ZrO2 in an industrial blender to obtain a first mixture with a lithium to metal (Ni, Co and Mn) ratio of 1.05 and Zr of 1000 ppm.

[0174] Step 3) First calcination: The first mixture obtained in step 2) is calcined at 935° C. for 10 hours in an oxidizing atmosphere to obtain a first calcined powder.

[0175] Step 4) Wet bead milling: The first calcined powder obtained in step 3) was bead milled, followed by a crushing and sieving process to obtain a ground powder. The weight ratio of bead milled solid to solution was 60%.

[0176] Step 5) Second calcination: The bead milled powder obtained from step 4) was heated at 775° C. for 12 hours in air to obtain a second calcined powder labeled as CEX3.

[0177] Due to the wet grinding in step 4), CEX3 is a single crystalline powder.

[0178] Example 3

[0179] The single crystalline positive electrode active material labeled EX3 was prepared according to the following steps:

[0180] Step 1) Mixing: CEX3 is mixed in an industrial blender with 250 ppm Al from Al2O3, 250 ppm B from H3BO3 powder and 3000 ppm W from WO3 powder, each relative to the total molar content of Ni, Mn and Co in CEX3, so as to obtain a mixture.

[0181] Step 2) Calcination: The mixture obtained in step 1) was calcined at 375°C for 8 hours in an oxidizing atmosphere to obtain a calcined body. The product was ground and marked as EX3.

[0182] Table 3. Overview of the composition and corresponding electrochemical properties of CEX1.1, CEX1.2, EXI, CEX2.1, CEX2.2, and EX2

[0183]

[0184] *Calculated by ICP measurement, M' is the total mole fraction of other elements analyzed by ICP

[0185] na: not available

[0186] Table 4. Summary of the composition and corresponding electrochemical properties of CEX3 and EX3

[0187]

[0188] Table 5. XPS analysis results of EX2 and ratios using ICP analysis

[0189]

[0190] * Calculated relative to the total mole fraction of Ni, Mn and Co analyzed by ICP

[0191] ** Calculated relative to the total mole fraction of Ni, Mn and Co analyzed by XPS

[0192] Table 3 summarizes the compositions of the embodiments and comparative examples and their corresponding electrochemical properties. Comparison between CEX1.1 and CEX1.2 shows that the addition of additional B in CEX1.2 slightly increases DQ1 and reduces IRRQ, but at the same time increases the undesirable internal resistance indicated by the high DCR at SOC50%. On the other hand, EX1, which has the same Ni / M content as CEX1.1 and CEX1.2, exhibits higher DQ1 and lower IRRRQ in the button cell test and exhibits lower DCR at SOC50%, as well as better cycle life in the full battery test, indicating the necessity of W. Similarly, EX2, which has the same Ni / M content as CEX2.1 and CEX2.2, exhibits higher DQ1 and lower IRRQ in the button cell test, and exhibits lower DCR at SOC50% in the full battery test. Figure 2a and Figure 2b Fully discharged DCR measurements from SOC 10% to SOC 90% are shown, where among the examples and counterexamples of each Ni / M group, EX1 and EX2 show the lowest discharge DCR at all SOC%.

[0193] Table 4 shows a comparison of electrochemical properties between Comparative Example 3 and Example 3, both of which have 70:30 mol% Ni:Mn. EX3, which contains Al, B, and W, generally shows improvements in electrochemical properties as indicated by higher DQ1 and lower IRRQ.

[0194] The above Tables 3 and 4 show that the presence of Al, B and W in EX1, EX2 and EX3 is beneficial to improving the electrochemical properties of DQ1 and IRRQ of the positive electrode active materials according to the present invention.

[0195] Table 5 summarizes the XPS analysis results of EX2, showing the Al, B and W fractions relative to the total molar fraction of Ni, Mn and Co. The table also compares the results with those of ICP. A molar ratio higher than 1 indicates that the Al, B and W are enriched in the surface of the positive electrode active material associated with the XPS measurement, and the signal of the XPS measurement is obtained from the first few nanometers (e.g., 1nm to 10nm) of the topmost part (i.e., the surface layer) of the sample. On the other hand, the molar ratio of Al, B and W obtained from the ICP measurement is obtained from the entire particle. Therefore, an XPS to ICP ratio higher than 1 indicates that the element Al, B or W is mainly present on the surface of the positive electrode active material. An XPS to ICP ratio higher than 1 was observed for Al, B and W in EX2.

[0196] Note that due to the manufacturing method, EX1 will also have a ratio of the prevalence of Al, B and W measured by XPS to the prevalence of Al, B and W measured by ICP that is significantly higher than 1.

[0197] Additionally, the XPS peak positions were correlated to the compounds obtained from the preparative method. Figure 3a The Al peak of EX2 is shown, which overlaps with the Ni3p peak, and Figure 3b The B1s peak of EX2 is shown. Peak deconvolution was performed based on peak position to separate the contribution of each compound according to the references listed in Table 2c. Figure 3a Three different Al-containing compounds and Ni3p contributions were separated in the results, where the results showed that EX2 contained Al2O3, LiAlO2 and LiAl on the surface. n Me 1-n O2. Figure 3b In the above, the B1s peak is deconvoluted into a peak belonging to H3BO3 and another peak belonging to a Li-BO compound having a similar peak position. The Li-BO compound may be, but is not limited to, Li2B4O7 and Li4B2O5.

Claims

1. A positive electrode active material for a lithium ion rechargeable battery, wherein the positive electrode active material is a powder, wherein the positive electrode active material comprises Li, M' and oxygen, wherein M' comprises: -Ni, the content of Ni is between 60.0 mol% and 75.0 mol% relative to M', -Co, the content x of Co is between 0.0 mol % and 20.0 mol % relative to M', - Mn, the content y of Mn is between 0.0 mol % and 35.0 mol % relative to M', -D, the content z of D is between 0.0 mol% and 2.0 mol% relative to M', wherein D comprises at least one element selected from the group consisting of Ba, Ca, Cr, Fe, Mg, Mo, Nb, S, Si, Sr, Ti, Y, V, Zn and Zr, and - Al and B and W, wherein the total content c of Al and B and W is between 0.1 mol % and 5.0 mol % relative to M', - where a, x, y, z and c are measured by ICP, - wherein a+x+y+c+z is 100.0 mol%, - wherein the positive electrode active material has an Al content Al A , B content A and W content A , where Al A , B A and W A is determined by ICP analysis, where Al A , B A and W A Expressed as the mole fraction compared to the sum of a and x and y, - wherein the powder exhibits an average Al fraction Al when measured by XPS analysis B , average B score B B and the average W score W B , where Al B , B B and W B Expressed as the mole fraction compared to the sum of the fractions of Co, Mn and Ni measured by XPS analysis, - Among them, the ratio Al B / Al A >1.0, - where ratio B B / B A >1.0, - where the ratio W B / W A >1.0, and The powder is a single crystal powder.

2. The positive electrode active material of claim 1, wherein a is at least 62.0 mol% relative to M' as measured by ICP.

3. The positive electrode active material of claim 1, wherein a is at least 64.0 mol% relative to M' as measured by ICP.

4. The positive electrode active material according to any one of claims 1 to 3, wherein the ratio of Al B / Al A >10.

5. The positive electrode active material according to any one of claims 1 to 3, wherein the ratio Al B / Al A >150.

6. The positive electrode active material according to any one of claims 1 to 3, wherein the ratio of Al B / Al A <800.

7. The positive electrode active material according to any one of claims 1 to 3, wherein the ratio B B / B A >10.

8. The positive electrode active material according to any one of claims 1 to 3, wherein the ratio B B / B A >30.

9. The positive electrode active material according to any one of claims 1 to 3, wherein the ratio B B / B A >115.

10. The positive electrode active material according to any one of claims 1 to 3, wherein the ratio B B / B A <500.

11. The positive electrode active material according to any one of claims 1 to 3, wherein the ratio W B / W A >10.

12. The positive electrode active material according to any one of claims 1 to 3, wherein the ratio W B / W A >50.

13. The positive electrode active material according to any one of claims 1 to 3, wherein the ratio W B / W A >115.

14. The positive electrode active material according to any one of claims 1 to 3, wherein the ratio W B / W A <500.

15. The positive electrode active material according to any one of claims 1 to 3, wherein the content x of Co is between 0.0 mol% and 2.0 mol% relative to M' as measured by ICP.

16. The positive electrode active material according to any one of claims 1 to 3, wherein the positive electrode active material has a median particle size D50 between 2.0 μm and 7.0 μm as determined by laser diffraction particle size analysis. A .

17. The positive electrode active material according to any one of claims 1 to 3, wherein M' comprises Al and B and W, each in an amount of at least 0.02 mol% relative to M' as measured by ICP. 18 . A battery cell comprising the positive electrode active material according to claim 1 .

19. Use of the positive electrode active material according to any one of claims 1 to 17 in a battery for any one of a portable computer, a mobile phone, an electric vehicle and an energy storage system.

20. The use according to claim 19, wherein the portable computer is a tablet computer.

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