Lithium-nickel composite oxides as cathode active materials for rechargeable lithium-ion batteries

Abstract

The present invention relates to a cathode active material for a rechargeable lithium-ion battery, wherein the cathode active material contains Li, M', and oxygen, M' is Ni with a content x of 60.0 mol% to 95.0 mol% relative to M', Co with a content y of 0 < y < 40.0 mol% relative to M', Mn with a content z of 0 < z < 70.0 mol% relative to M', and D with a content a of 0 < a < 2.0 mol% relative to M', where D contains elements other than Li, O, Ni, Co, Mn, F, W, and B, D, F with a content b > 0, preferably 0.1 mol% to 4.0 mol% relative to M', W with a content c of 0.1 mol% to 4.0 mol% relative to M', and B with a content e of 0 < e < 4.0 mol% relative to M', where x, y, z, a, c, e, and c are measured by inductively coupled plasma optical emission spectrometry (ICP-OES), b is measured by ion chromatography (IC), x + y + z + a + b + c + e = 100.0 mol%, and the cathode active material has an F content F defined by formula (I) A and a W content W defined by formula (II) A and has an F content F B and a W content W B where F B and W B are determined by XPS analysis, and F B and W B are each represented as a molar fraction compared to the total molar fraction of Co, Mn, Ni, F, W, and B measured by X-ray photoelectron spectroscopy, and the ratio F B / F A > 1.0, and the ratio W B / W A > 1.0, to provide a cathode active material. JPEG2024520028000025.jpg23170

Description

[Technical Field]

[0001] The present invention relates to a lithium nickel-based oxide positive electrode active material for lithium ion secondary batteries (LIBs) suitable for electric vehicles (EVs) and hybrid electric vehicles (HEVs), which contains fluorine-containing lithium transition metal-based oxide particles. [Background technology]

[0002] The positive electrode active material is defined as a material that is electrochemically active in the positive electrode, and is understood to be a material that can capture and release Li ions when exposed to a voltage change over a period of time. Summary of the Invention [Problem to be solved by the invention]

[0003] It is therefore an object of the present invention to provide a cathode active material having one or more improved properties, such as reduced carbon content and increased cycle life as indicated by capacity fade rate (QF) in electrochemical cells. [Means for solving the problem]

[0004] Acknowledgments This invention was made with the support of the Materials / Components Technology Development Program through the Korea Industrial Technology Assessment Agency, funded by the Ministry of Trade, Industry and Energy (MOTIE, Republic of Korea). [Project Name: Development of 8C Rate Class High Output (High Discharge Rate) Lithium-ion Secondary Battery / Project Number: 20011287 / Contribution Rate: 100%]

[0005] The object is to provide a cathode active material for a lithium ion battery, the cathode active material comprising Li, M' and oxygen, wherein M' is Ni with a content x of 60.0 mol% to 95.0 mol%, preferably 80.0 mol% to 95 mol%, relative to M'; Co with a content y of 0≦y≦40.0 mol% relative to M'; Mn with a content z of 0≦z≦70.0 mol% relative to M'; D, with a content a of 0≦a≦2.0 mol% relative to M′, wherein D contains elements other than Li, O, Ni, Co, Mn, F, W and B, preferably D contains 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; F with a content b of b>0, preferably 0.1 mol% to 4.0 mol% relative to M'; W with a content c of c>0, preferably 0.1 mol% to 4.0 mol% relative to M'; Optionally, S with a content d of 0≦d≦4.0 mol % relative to M′; B, with a content e of 0≦e≦4.0 mol% relative to M′; and x, y, z, a, e, and c are measured by ICP-OES; b is measured by IC x+y+z+a+b+c+d+e is 100.0 mol%, The positive electrode active material is

[0006]

number

[0007] The F content, F, is defined as A and,

[0008]

number

[0009] The W content, W, is defined as A and, The positive electrode active material has an F content of F B and W content W B and F B and W B was determined by XPS analysis, and F B and W Bare each expressed as a mole fraction relative to the sum of the mole fractions of Co, Mn, Ni, F, W, S, and B as determined by XPS analysis; ratio F B / F A >1.0, ratio W B / W A >1.0.

[0010] In some cases, the positive electrode active material further comprises S with a content d>0, preferably 0.01 mol%≦d≦3.0 mol%, and the positive electrode active material

[0011]

number

[0012] The S content, defined as S A and The positive electrode active material has an S content determined by XPS analysis. B and S B is expressed as a mole fraction relative to the sum of the mole fractions of Co, Mn, Ni, F, W, S, and B as determined by XPS analysis, ratio S B / S A >1.0.

[0013] The present invention relates to the following embodiments.

[0014] Embodiment 1 In a first aspect, the present invention provides an active cathode material for a lithium ion battery, the active cathode material comprising Li, M′, and oxygen, wherein M′ is: Ni with a content x of 60.0 mol% to 95.0 mol% relative to M'; Co with a content y of 0≦y≦40.0 mol% relative to M'; Mn with a content z of 0≦z≦70.0 mol% relative to M'; D, with a content a of 0≦a≦2.0 mol% relative to M′, wherein D contains elements other than Li, O, Ni, Co, Mn, F, W and B, preferably D contains 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; F with a content b of 0.1 mol% to 4.0 mol% relative to M'; W having a content c of 0.1 mol% to 4.0 mol% relative to M'; Optionally, S with a content d of 0≦e≦4.0 mol % relative to M′; B, with a content e of 0≦e≦4.0 mol % relative to M′; and x, y, z, a, e, d, and c are measured by ICP-OES; b is measured by IC x+y+z+a+b+c+d+e is 100.0 mol%, The positive electrode active material is

[0015]

number

[0016] The F content, F, is defined as A and,

[0017]

number

[0018] The W content, W, is defined as A and, The positive electrode active material has an F content of F B and W content W B and F B and W B was determined by XPS analysis, and F B and W B are each expressed as a mole fraction relative to the sum of the mole fractions of Co, Mn, Ni, F, W, S, and B as determined by XPS analysis; ratio F B / F A >1.0, ratio W B / W A >1.0.

[0019] Preferably, F B / F A >2.0, more preferably F B / F A >5.0, most preferably F B / F A ≧10.0.

[0020] Preferably, F B / F A <60.0, more preferably F B / F A <50.0, most preferably F B / F A ≦40.0.

[0021] Preferably, W B / W A >2.0, preferably W B / W A >5.0, most preferably W B / W A ≧30.0.

[0022] Preferably, W B / W A <100.0, more preferably W B / W A <90.0, most preferably W B / W A ≦85.0.

[0023] Preferably, the Ni content is x≧65.0 mol %, more preferably x≧70.0 mol %, even more preferably more than 75 mol % relative to M′.

[0024] Preferably, the Ni content is x≦93.0 mol %, more preferably x≦91.0 mol %, even more preferably less than 87 mol % relative to M′.

[0025] Preferably, the Co content is y>2.0 mol%, more preferably y≧3.0 mol%, even more preferably y≧4.0 mol% relative to M′.

[0026] In one embodiment, the Co content is y<20 mol %, more preferably y<15 mol %, even more preferably y<12.5 mol %, relative to M'.

[0027] Preferably, the Mn content is z>1 mol %, more preferably ≧3.0 mol %, and even more preferably z≧4.0 mol %, relative to M′.

[0028] In one embodiment, the Mn content is y<20 mol %, more preferably Mn<15 mol %, even more preferably <12.5 mol % relative to M'.

[0029] Preferably, a is 0.01 mol % to 2.0 mol % relative to M', and more preferably, a is 0.1 mol % to 1.8 mol %.

[0030] Preferably, B is present in a content b between 0.1 mol % and 2 mol %, even more preferably between 0.2 mol % and 1 mol %.

[0031] Preferably, F is present in a content b between 0.1 mol % and 2 mol %, even more preferably between 0.2 mol % and 1 mol %.

[0032] Preferably, W is present in a content b between 0.1 mol % and 2 mol %, even more preferably between 0.2 mol % and 1 mol %.

[0033] In some cases, the positive electrode active material of the present invention further contains S in a content of 0 to 4.0 mol %, preferably 0.1 mol % to 2 mol %, and even more preferably 0.2 mol % to 1 mol %, relative to M'.

[0034] Preferably, the positive electrode active material is in the form of a powder.

[0035] For the sake of completeness, it should be noted that in the definition of the present invention, when the content of an element is stated using the symbol "0≦", this means that the presence of said element is optional.

[0036] Embodiment 2 In a second embodiment, preferably according to embodiment 1, the material comprises B with a content e>0, preferably 0.01 mol%≦e≦4.0 mol%, and the positive electrode active material is

[0037]

number

[0038] B content defined as B A and The positive electrode active material has a B content B determined by XPS analysis. B B B is expressed as a mole fraction compared to the sum of the mole fractions of Co, Mn, Ni, F, W, S, and B as determined by XPS analysis, Ratio B B / B A >1.0.

[0039] Preferably, B B / B A >2.0.

[0040] More preferably, B B / B A >5.0, most preferably B B / B A ≧20.0.

[0041] Preferably, B B / B A <60.0, more preferably B B / B A ≦50.0.

[0042] Embodiment 3 In a third aspect, the present invention provides a battery comprising the cathode active material of the present invention.

[0043] In a further aspect, the present invention provides the use of a battery according to the present invention in a portable computer, a tablet, a mobile phone, an electric vehicle, or an energy storage system.

[0044] Embodiment 4: Fourth embodiment c A cathode active material for a lithium ion battery, the cathode active material comprising Li, M', and oxygen, wherein M' is Ni with a content x of 60.0 mol% to 95.0 mol% relative to M'; Co with a content y of 0≦y≦40.0 mol% relative to M'; Mn with a content z of 0≦z≦70.0 mol% relative to M'; D, with a content a of 0≦a≦2.0 mol% relative to M′, and D containing at least one element selected from the group consisting of Al, Ba, Ca, Cr, Fe, Mg, Mo, Nb, Si, Sr, Ti, Y, V, Zn, and Zr; F with a content b of 0.1 mol% to 4.0 mol% relative to M'; W having a content c of 0.1 mol% to 4.0 mol% relative to M'; S with a content d of 0≦d≦3.0 mol% relative to M'; B having a content e of 0≦e≦4.0 mol% relative to M', x, y, z, a, d, e, and c are measured by ICP-OES, b is measured by IC x+y+z+a+b+c+d+e is 100.0 mol%, The positive electrode active material is

[0045]

number

[0046] The F content, F, is defined as A and,

[0047]

number

[0048] The W content, W, is defined as A and, The positive electrode active material has an F content of F B and W content W B and F B and W B was determined by XPS analysis, and F B and W B are each expressed as a mole fraction relative to the sum of the mole fractions of Co, Mn, Ni, F, W, B, and S as determined by XPS analysis, ratio F B / F A >1.0, ratio W B / W A >1.0.

[0049] Preferably, F B / F A >2.0.

[0050] Preferably, W B / W A >1.0.

[0051] For the sake of completeness, it should be noted that in the definition of the present invention, when the content of an element is stated using the symbol "0≦", this means that the presence of said element is optional.

[0052] Embodiment 5 In a fifth embodiment, preferably according to the fourth embodiment, the material comprises S with a content d of 0.01 mol%≦d≦3.0 mol%, and the positive electrode active material is

[0053]

number

[0054] The S content, defined as S A and The positive electrode active material has an S content determined by XPS analysis. B and S B is expressed as a mole fraction relative to the sum of the mole fractions of Co, Mn, Ni, F, W, S, and B as determined by XPS analysis, ratio S B / S A >1.0.

[0055] Preferably, S B / S A >2.0.

[0056] Embodiment 6 In a sixth embodiment, preferably according to embodiment 4 or 5, the material comprises B with a content e of 0.01 mol%≦e≦4.0 mol%, and the positive electrode active material is

[0057]

number

[0058] Preferably, B B / B A >2.0.

[0059] Embodiment 7 In a seventh embodiment, the present invention provides a cathode active material comprising Li, M′, and oxygen, wherein M′ is: Ni with a content x of 60.0 mol% to 95.0 mol% relative to M'; Co with a content y of 0≦y≦40.0 mol% relative to M'; Mn with a content z of 0≦z≦70.0 mol% relative to M'; D, with a content a of 0≦a≦2.0 mol% relative to M', and D containing at least one element selected from the group consisting of Al, B, Ba, Ca, Cr, Fe, Mg, Mo, Nb, S, Si, Sr, Ti, Y, V, Zn, and Zr; F with a content b of 0.1 mol% to 4.0 mol% relative to M'; W having a content c of 0.0 mol% to 4.0 mol% relative to M'; S with a content d of 0.01 mol% to 3.0 mol% relative to M'; B having a content e of 0≦e≦4.0 mol%, x, y, z, a, c, d, and e are measured by ICP-OES; b is measured by IC x+y+z+a+b+c+d+e is 100.0 mol%, The positive electrode active material is

[0060]

number

[0061] The F content, F, is defined as A and,

[0062]

number

[0063] The S content, S, is defined as A and, The positive electrode active material has an F content of F B F B was determined by XPS analysis, and F B and S B are each expressed as a mole fraction relative to the sum of the mole fractions of Co, Mn, Ni, F, W, B, and S as determined by XPS analysis, ratio F B / F A >1.0, ratio S B / S A>1.0.

[0064] Preferably, F B / F A >2.0.

[0065] Preferably, S B / S A >2.0. DETAILED DESCRIPTION OF THE INVENTION

[0066] The active cathode materials according to the present invention typically have one or more of the following advantages: (i) reduced carbon content and (ii) increased cycle life, which is believed to be achieved by the cathode materials comprising fluorine and tungsten, and optionally boron.

[0067] Typically, the cathode materials of the invention comprise secondary particles having a median diameter D50 of at least 2 μm, preferably at least 3 μm, as determined by laser diffraction particle size analysis.

[0068] Preferably, the material has a median secondary particle size D50 of at most 16 μm, preferably at most 15 μm, as determined by laser diffraction particle size analysis.

[0069] It will be apparent that further product embodiments according to the present invention may be provided by combining features covered by the various product embodiments described herein above.

[0070] In a further embodiment of the present invention, the cathode material of the present invention comprises: Step 1) mixing a lithium transition metal oxide with an F-containing compound and a W-containing compound to obtain a mixture; Step 2) heating the mixture in an oxidizing atmosphere at a temperature of 250° C. or higher and lower than 500° C. to obtain a positive electrode active material.

[0071] Preferably, the F-containing compound used in step 1) is PVDF.

[0072] Preferably, the amount of F used in step 1) is 300 ppm to 3000 ppm based on the weight of the lithium transition metal oxide, and more preferably, the amount of F used in step 1) is 500 ppm to 2000 ppm based on the weight of the lithium transition metal oxide.

[0073] Preferably, the W-containing compound used in step 1) is WO3.

[0074] Preferably, the amount of W is 2000 ppm to 9000 ppm based on the weight of the lithium transition metal oxide, and more preferably, the amount of W used in step 1) is 3000 ppm to 8000 ppm based on the weight of the lithium transition metal oxide.

[0075] More preferably, in step 1), a B-containing compound, preferably H3BO3, is added together with the F- and W-containing compounds in an amount of 100 ppm to 3000 ppm of B relative to the weight of the lithium transition metal oxide.

[0076] Furthermore, the method includes an additional step between step 1 and step 2, in which the additional step is combining the mixture from step 1) with a solution containing an S-containing compound in an amount of 500 ppm to 5000 ppm based on the weight of the lithium transition metal oxide.

[0077] Preferably, the S-containing compound used is Al2(SO4)3.

[0078] Optionally, a compound containing an element other than Li, O, Ni, Co, Mn, F, W, and B is added to the positive electrode material, and preferably the element includes at least one element selected from the group consisting of Al, Ba, Ca, Cr, Fe, Mg, Mo, Nb, S, Si, Sr, Ti, Y, V, Zn, and Zr. Preferably, the element-containing compound is added during the mixing step together with the lithium source when preparing the transition metal oxide. Alternatively, the element-containing compound may be added during precursor preparation.

[0079] In the framework of the present invention, ppm means parts per million for units of concentration, with 1 ppm = 0.0001% by weight.

[0080] In the following detailed description, preferred embodiments are described to facilitate the practice of the present invention. While the present invention is described with reference to these particular preferred embodiments, it will be understood that the present invention is not limited to these preferred embodiments. The present invention includes numerous alternatives, modifications, and equivalents that will be apparent from a consideration of the following detailed description and the accompanying drawings.

[0081] A) ICP-OES analysis The Li, Ni, Mn, Co, W, and B (optionally S) contents of the positive electrode active material powder were measured using inductively coupled plasma-optical emission spectrometry (ICP-OES) using an Agilent ICP 720-OES. In an Erlenmeyer flask, 2 grams of the product powder sample was dissolved in 10 mL of high-purity hydrochloric acid. The flask was covered with glass and heated on a hot plate at 380 °C until the precursor was completely dissolved. After cooling to room temperature, the solution in the Erlenmeyer flask was poured into a 250 mL volumetric flask. The volumetric flask was then filled with deionized water up to the 250 mL mark, followed by thorough homogenization. An appropriate amount of the solution was removed with a pipette and transferred to a 250 mL volumetric flask for the second dilution. The volumetric flask was then filled with an internal standard and 10% hydrochloric acid up to the 250 mL mark, followed by homogenization. Finally, this 50 mL solution was used for ICP-OES measurement.

[0082] B)PSD 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 equipped with a Hydro MV wet dispersion accessory after dispersing each powder sample in an aqueous medium. Sufficient ultrasonic irradiation and stirring were applied to improve powder dispersion, and a suitable surfactant was introduced. D50 was defined as the particle size at 50% of the cumulative volume percent distribution obtained from the Malvern Mastersizer 3000 using Hydro MV measurements.

[0083] C) Ion chromatography (IC) analysis The amount of F in the positive electrode active material powder was measured using ion chromatography (IC) with a Dionex ICS-2100 (Thermo Scientific). A 250-mL volumetric flask and a 100-mL volumetric flask were rinsed with a 1:1 volumetric mixture of 65 wt% HNO3 and deionized water before use, and then the flasks were rinsed with deionized water at least five times. 2 mL of HNO3, 2 mL of H2O2, and 2 mL of deionized water were mixed as a solvent. 0.5 grams of powder sample was dissolved in the mixed solvent. The solution was completely transferred from the container to a 250-mL volumetric flask and filled with deionized water up to the 250-mL mark. The filled flask was thoroughly shaken to ensure the solution was homogeneous. 9 mL of the solution from the 250-mL flask was transferred to a 100-mL volumetric flask. Fill a 100 mL volumetric flask with deionized water up to the 100 mL mark and shake thoroughly to obtain a homogeneous sample solution. 2 mL of the sample solution was inserted into a 5 mL IC vial via a syringe-on guard cartridge for IC measurement.

[0084] D) Coin Cell Test Dl) Coin cell fabrication For the fabrication of the positive electrode, a slurry containing the positive electrode active material powder, conductor (Super P, Timcal), and binder (KF#9305, Kureha) in a solvent (NMP, Mitsubishi) in a weight ratio of 96.5:1.5:2.0 was prepared using a high-speed homogenizer. The homogenized slurry was spread onto one side of aluminum foil using a doctor blade coater with a gap of 170 pm. The foil coated with the slurry was dried in an oven at 120 °C and then pressed using a calendar tool. It was then dried again in a vacuum oven to completely remove residual solvent in the electrode film. Coin cells were assembled in an argon-filled glove box. A separator (Celgard 2320) was placed between the positive electrode and a piece of lithium foil used as the negative electrode. 1M LiPF6 in EC / DMC (1:2) was used as the electrolyte and was dispensed between the separator and the electrode. The coin cell is then completely sealed to prevent electrolyte leakage.

[0085] D2) Test method The test method is a conventional "constant cutoff voltage" test. Conventional coin cell testing in this invention follows the schedule shown in Table 2. Each cell is cycled at 25°C using a Toscat-3100 computer-controlled galvanostatic cycling station (manufactured by Toyo). The schedule uses a 1C current definition of 220 mA / g in the 4.3V to 3.0V / Li metal window range. The capacity fade rate (QF) is calculated by the following formula:

[0086]

number

[0087] In the formula, DQ1 is the discharge capacity at the first cycle, DQ7 is the discharge capacity at the seventh cycle, and DQ34 is the discharge capacity at the 34th cycle.

[0088] [Table 1]

[0089] E) X-ray photoelectron spectroscopy (XPS) analysis In the present invention, X-ray photoelectron spectroscopy (XPS) is used to analyze the surface of positive electrode active material powder particles. In XPS measurements, signals are acquired from the top of the sample, i.e., the first few nanometers (e.g., 1 nm to 10 nm) of the surface layer. Therefore, all elements measured by XPS are contained in the surface layer.

[0090] For the surface analysis of the positive electrode active material powder particles, XPS measurements are performed using a Thermo K-α+ spectrometer (Thermo Scientific).

[0091] Monochromatic Al Kα radiation (hυ = 1486.6 eV) is used with a spot size of 400 μm and a measurement angle of 45°. An extensive survey scan to identify the elements present on the surface is performed with a pass energy of 200 eV. The C1s peak with maximum intensity (or center) at a binding energy of 284.8 eV is used as the calibration peak position after data collection.

[0092] Then, for each identified element, at least 10 precise narrow scans at 50 eV are performed to determine the exact surface composition.

[0093] Curve fitting was performed with CasaXPS version 2.3.19PR1.0 (Casa Software) using Shirley-type background processing and Scofield sensitivity coefficients. Fitting parameters are according to Table 2a. The lineshape GL(30) is the Gaussian / Lorentzian product formula for the 70% Gaussian and 30% Lorentzian lines. LA(α, β, m) is the asymmetric lineshape, where α and β define the tail broadening of the peak and m defines the width.

[0094] [Table 2]

[0095] For Co, W, and S peaks, limits are set for each defined peak according to Table 2b. W5p3 is not quantified.

[0096] [Table 3]

[0097] The surface contents of F, W, S, and B are expressed as the mole fraction of F, W, S, and B at the surface of a particle divided by the total content of Ni, Mn, Co, F, W, B, and S at that surface, as determined by XPS. They are calculated as follows:

[0098]

number

[0099] F) Carbon analyzer The carbon content of the positive electrode active material powder is measured using a Horiba Emia-Expert carbon / sulfur analyzer. 1 g of the positive electrode active material powder is placed in a ceramic crucible in a high-frequency induction furnace. 1.5 g of tungsten and 0.3 g of tin as promoters are added to the crucible. The powder is heated at a programmable temperature, and the gases produced during combustion are then analyzed by an infrared detector. The carbon concentration is determined by CO2 and CO analysis.

[0100] The invention is further illustrated by the following (non-limiting) examples.

[0101] Comparative Example 1 CEX1 was obtained by solid-state reaction between a lithium source and a transition metal-based source precursor, which was carried out as follows. 1) Co-precipitation: Transition metal oxide-hydroxide precursors were prepared using a co-precipitation process in a batch reactor. Nickel manganese cobalt sulfate, sodium hydroxide, and ammonia were fed to the reactor under controlled conditions. The concentrations of the metal salts were varied during precipitation to form a concentration gradient of Ni and Mn from the center to the edge of the particle. The total metal composition was determined by ICP-OES to be Ni. 0.85 Mn 0.10 Co 0.05 It was. 2) Blending: The precursor prepared in step 1) was homogeneously blended with LiOH as the lithium source in an industrial blending apparatus at a lithium to metal M' (Li / M') ratio of 1.005. 3) First Heat: The blend from step 2) was sintered at 765°C for 10 hours under an oxygen atmosphere. The product was crushed, classified, and sieved. CEX1 had a D50 of 10.5 pm as determined by PSD Method B above. The positive electrode active material CEX1 contained Ni エッジ / Ni センター =0.91, Mn エッジ / Mn センター It was determined by the CS-EDS method F described above that the grains have a concentration gradient of Ni and Mn from the edge to the core, where σ = 2.33.

[0102] Example 1 EX1 was made by mixing CEX1 with PVDF powder and WO powder in 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.

[0103] Example 2 EX2 was made 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.

[0104] The process of using PVDF and WO3 in the preparation of EX1, and the process of using PVDF, WO3 and H3BO3 in the preparation of EX2 are respectively F B / F A >1.0, W B / W A >1.0, and B B / B A >1.0, F B , W B , and B B is obtained by XPS measurement, and F A , W A , and B A is obtained by ICP-OES measurement.

[0105] [Table 4]

[0106] For the examples shown in Table 4 above, S greater than 0 B , F B , B b , and W B indicates that the element is present on the surface of the cathode active material, in relation to the XPS measurement, where the signal is obtained from the top of the sample, i.e., the first few nanometers (e.g., 1 nm to 10 nm) of the surface layer. On the other hand, the F obtained from the ICP-OES measurement A , B A , and W A The atomic ratio of F is from the whole particle. B / F A , B B / B A , and W B / W A The ratio of XPS to ICP-OES of greater than 1 indicates that the elements F, B and W are mainly present on the surface of the positive electrode active material.

[0107] Table 4 above shows that the positive electrode active materials EX1 and EX2, each containing F, W, and optionally B according to the present invention, have improved carbon content reduction and QF reduction properties when used in an electrochemical cell compared to the comparative example CEX1.

[0108] Comparative Example 3.1 CEX3.1 was obtained by solid-state reaction between a lithium source and a transition metal-based source precursor, which was carried out as follows. 1) Coprecipitation: The metal composition Ni was obtained by a coprecipitation process using nickel-manganese-cobalt sulfate, sodium hydroxide, and ammonia mixed in a large continuous stirred tank reactor (CSTR). 0.80 Mn 0.10 Co 0.10 A transition metal oxide hydroxide precursor having the following structure was prepared. 2) Blending: The precursor prepared in step 1) was homogeneously blended with LiOH as the lithium source in an industrial blending apparatus at a lithium to metal M' (Li / M') ratio of 1.00. 3) First heat: The blend from step 2) was sintered under oxygen atmosphere at 805°C for 12 hours. The product was crushed, classified and sieved to obtain the first heat powder. 4) Wet mixing: The first heated powder from step 3) was mixed with an aluminum sulfate solution made by dissolving approximately 3800 ppm of Al2(SO4)3 powder in deionized water at 3.5 wt% relative to the weight of the first heated powder. 5) Second heating: The mixture obtained from step 4) was heated at 385°C for 8 hours under oxygen atmosphere, followed by grinding and sieving to obtain CEX3.1 with a D50 of about 13µm.

[0109] Comparative Example 3.2 CEX3.2 was prepared according to 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 WO powder was mixed with the first heated powder.

[0110] Example 3.1 EX3.1 was prepared according to 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 of F from PVDF powder and 4000 ppm of W from WO powder were mixed with the first heated powder.

[0111] Example 3.2 EX3.2 was prepared according to 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 of F from PVDF powder and 6000 ppm of W from WO powder were mixed with the first heated powder.

[0112] Example 3.3 EX3.3 was prepared according to 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 WO powder were mixed with the first heated powder.

[0113] In EX3.1, EX3.2, and EX3.3, the step of mixing PVDF, WO3, and Al2(SO4)3 compounds followed by heat treatment is B / F A >1.0, W B / W A >1.0, and S B / S A >1.0, respectively, F B , W B , and S B is obtained by XPS measurement, and F A , W A , S A is obtained by ICP-OES measurement.

[0114] [Table 5]

[0115] F greater than 0 B , S B , B b , and W Bindicates that the element is present on the surface of the cathode active material, in relation to the XPS measurement, where the signal is obtained from the top of the sample, i.e., the first few nanometers (e.g., 1 nm to 10 nm) of the surface layer. On the other hand, the F obtained from the ICP-OES measurement A , S A , B A , and W A The atomic ratio of F is from the whole particle. B / F A , S B / S A , B B / B A , and W B / W A The ratio of XPS to ICP-OES of greater than 1 indicates that the elements F, S, B, and W are mainly present on the surface of the positive electrode active material.

Claims

1. 1. A cathode active material for a rechargeable lithium ion battery, the cathode active material comprising Li, M′, and oxygen, wherein M′ is: Ni with a content x of 60.0 mol% to 95.0 mol% relative to M'; Co with a content y of 0≦y≦40.0 mol% relative to M′; Mn having a content z of 0≦z≦70.0 mol% relative to M′; D having a content a of 0≦a≦2.0 mol% relative to M′, wherein D contains elements other than Li, O, Ni, Co, Mn, F, W and B; F with a content b of b>0 relative to M'; W with a content c of c>0 relative to M'; S with a content d of 0≦d≦4.0 mol% relative to M′; B has a content e of 0≦e≦4.0 mol% relative to M′; and x, y, z, a, d, e, and c are measured by inductively coupled plasma optical emission spectroscopy (ICP-OES); b is measured by ion chromatography (IC), x+y+z+a+b+c+d+e is 100.0 mol%, The positive electrode active material is [Equation 1] The F content, F, is defined as Ａ and, [Equation 2] The W content W is defined as Ａ and, The positive electrode active material has an F content of F Ｂ and W content W Ｂ and F Ｂ and W Ｂ was determined by X-ray photoelectron spectroscopy, and F Ｂ and W Ｂ are each expressed as a mole fraction compared to the sum of the mole fractions of Co, Mn, Ni, F, W, S, and B as determined by XPS analysis; ratio F Ｂ / F Ａ >1.0, Ratio W Ｂ / W Ａ >1.

0.

2. The positive electrode active material further contains S with a content d of d>0, and the positive electrode active material is [Equation 3] The S content, S, is defined as Ａ and The positive electrode active material has an S content S determined by XPS analysis. Ｂ and S Ｂ is expressed as a mole fraction compared to the sum of the mole fractions of Co, Mn, Ni, F, W, S, and B as determined by XPS analysis; ratio S Ｂ / S Ａ The positive electrode active material according to claim 1 , wherein the ρ is >1.

0.

3. A positive electrode active material having e>0, wherein the positive electrode active material is [Equation 4] B content B defined as Ａ and The positive electrode active material has a B content B determined by XPS analysis. Ｂ and B Ｂ is expressed as a mole fraction compared to the sum of the mole fractions of Co, Mn, Ni, F, W, S, and B as determined by XPS analysis; Ratio B Ｂ / B Ａ The positive electrode active material according to claim 1 , wherein the ρ is >1.

0.

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

0.

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

0.

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

0.

7. 2. The cathode active material of claim 1, 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.

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

9. The following consecutive Step 1) mixing a lithium transition metal oxide with an F-containing compound and a W-containing compound to obtain a mixture; and step 2) heating the mixture in an oxidizing atmosphere at a temperature of 250° C. or higher and lower than 500° C. to obtain the cathode active material.

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

11. The W-containing compound is WO ３ The method of claim 9, wherein

12. The method according to claim 9, wherein in step 1), a B-containing compound is added together with the F-containing compound and the W-containing compound.

13. The B-containing compound is H ３ BO ３ The method of claim 12, wherein

14. 10. The method of claim 9, wherein the method further comprises an additional step between step 1 and step 2, wherein the additional step is combining the mixture from step 1) with a solution containing an S-containing compound.

15. The S-containing compound used is Al ２ (SO ４ ) ３ The method of claim 14, wherein

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

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

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