Positive electrode active material for rechargeable batteries

Abstract

The present invention provides a positive electrode active oxide material for a rechargeable battery, comprising lithium, nickel, and at least one metal selected from the group consisting of manganese and cobalt, wherein the positive electrode active oxide material has a single crystal morphology, and the surface layer further comprises aluminum and fluorine, wherein the atomic ratio of Al to the total amount of Ni, Mn, and / or Co is 1.0 to 7.0, and the atomic ratio of F to the total amount of Ni, Mn, and / or Co in the surface layer is 0.5 to 6.0, as determined by XPS analysis.

Description

[Technical Field]

[0001] The present invention relates to a cathode active oxide material (hereinafter also referred to as cathode active material) for rechargeable batteries, particularly for solid state battery (SSB) applications, comprising lithium, oxygen, nickel, and at least one metal selected from the group consisting of manganese and cobalt.

[0002] More specifically, the present invention relates to a single crystal positive electrode active material powder particulate positive electrode active material.

[0003] The positive electrode active material is defined as a material that is electrochemically active in the positive electrode and is capable of capturing and releasing Li-ions when exposed to a voltage change over a period of time. [Background technology]

[0004] Such single-crystal cathode active material powders are known, for example, from WO 2019 / 185349, which discloses a method for preparing the single-crystal cathode active material powder. This morphology is generally preferred for SSB applications, as the monolithic morphology ensures good surface contact between the solid electrolyte and the cathode active material particles. However, undesired side reactions at the interface between the cathode active material particles and the solid electrolyte can degrade the electrochemical properties. Side reactions such as metal dissolution are particularly severe in polymer SSBs operating at higher temperatures, resulting in undesirably high leakage capacitance (Q). total ) Summary of the Invention [Problem to be solved by the invention]

[0005] It is an object of the present invention to provide a cathode active material powder for rechargeable batteries that reduces leakage current and improves battery cell durability and performance. More specifically, it is an object of the present invention to provide a cathode active material for lithium ion batteries, particularly for SSB applications, that has a total leakage capacity (Q) of up to 35 mAh / g, or even up to 20 mAh / g, as determined by the analytical method of the present invention.total The object of the present invention is to provide a positive electrode active material having the following properties: [Means for solving the problem]

[0006] This object is achieved by providing an active cathode material for a rechargeable battery according to claim 1. Indeed, it has been observed that improved Qtotal, and therefore reduced leakage capacity, is achieved in lithium-ion batteries using the active cathode material powder according to the invention, as shown by EX1 and EX2 and supported by the results provided in Table 3. EX1 teaches an active cathode material comprising single-crystalline particles containing the elements aluminum and fluorine, in which the atomic ratio of Al to the total atomic content of Ni, Mn, and / or Co is 3.28, as determined by XPS analysis, and the atomic ratio of F to the total atomic content of Ni, Mn, and / or Co is 1.86, as determined by XPS analysis.

[0007] The present invention further provides a polymer battery comprising the active cathode material according to the first aspect of the present invention, an electrochemical cell comprising the active cathode material according to the first aspect of the present invention, a method of making the active cathode material according to the first aspect of the present invention, and the use of the active cathode material according to the first aspect of the present invention in a battery of any one of a portable computer, a tablet, a mobile phone, an electric vehicle, and an energy storage system.

[0008] For further guidance and to better understand the teachings of the present invention, the drawings are included. The drawings are intended to aid in the explanation of the invention and are not intended to limit the invention disclosed herein. The figures and symbols contained therein have meanings commonly understood by those skilled in the art to which the invention pertains. [Brief explanation of the drawings]

[0009] [Figure 1] 1 shows a scanning electron microscope (SEM) image of a positive electrode active material powder of EX1 having a single crystal morphology. [Figure 2] 1 shows an X-ray photoelectron spectroscopy (XPS) graph showing the presence of Al2p and FIs peaks in EX2 compared to CEX2. [Figure 3] Figure 1 shows the effect of surface treatment on the Qtotal values ​​of the EX1 and EX2 cathode active materials compared to CEX1, CEX2, CEX3A, and CEX3B. The X-axis is the surface treatment, B represents before surface treatment, and A represents after surface treatment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Unless otherwise defined, all terms used in disclosing the present invention, including technical and scientific terms, have the meanings commonly understood by one of ordinary skill in the art to which this invention belongs. By way of further guidance, definitions of terms are included to better understand the teachings of the present invention. As used herein, the following terms have the following meanings: When an element is referred to as being "on" another element, it is understood that it can be directly on the other element, or that intervening elements can be present between them. In contrast, when an element is referred to as being "directly on" another element, there are no intervening elements present.

[0011] While the terms "first," "second," "third," etc. may be used herein to describe various elements, components, regions, layers, and / or sections, it is understood that these elements, components, regions, layers, and / or sections should not be limited by these terms. These terms are used only to distinguish one element, component, region, layer, or section from another element, component, region, layer, or section. Thus, a "first element," "component," "region," "layer," or "section" discussed below could be referred to as a second element, component, region, layer, or section without departing from the teachings herein.

[0012] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms, including "at least one," unless the content clearly dictates otherwise. "At least one" should not be construed as limiting "a" or "an."

[0013] It will be further understood that the terms "comprises" and / or "comprising" or "includes" and / or "including", as used herein, specify the presence of stated features, regions, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, components, and / or groups thereof.

[0014] Spatially relative terms such as "beneath," "below," "lower," "above," and "upper" may be used herein for ease of description to describe the relationship of one element or feature to another element or feature, as shown in the figures. It is understood that spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures were turned over, elements described as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the exemplary term "below" can encompass both an orientation of above and below. The device may be oriented differently (rotated 90 degrees or at another orientation), and the spatially relative descriptors used herein would be interpreted accordingly.

[0015] As used herein, "about" referring to a measurable value such as a parameter, amount, duration, etc., is meant to encompass a variation of no more than ±20%, preferably no more than ±10%, more preferably no more than ±5%, even more preferably no more than ±1%, and still more preferably no more than ±0.1% from the specified value, provided such variation is appropriate for the practice of the disclosed invention, although it should be understood that the value referred to by the modifier "about" is itself specifically disclosed.

[0016] The recitation of numerical ranges by endpoints includes not only the recited endpoints but also all numbers and fractions subsumed within that range. All percentages, unless otherwise defined or unless a different meaning is apparent to one of ordinary skill in the art from their use and the context in which they are used, are understood to be percent by weight, abbreviated as "wt %," or percent by volume, abbreviated as "vol %."

[0017] positive electrode active material In a first aspect, the present invention provides an active cathode material for a rechargeable battery, comprising lithium, nickel, and at least one metal selected from the group consisting of manganese and cobalt. The present invention particularly relates to an active cathode material, the particles of which have a single crystalline morphology. In the context of the present invention, single crystalline morphology refers to the morphology of a single primary particle having a monolithic structure, or of secondary particles consisting of less than five primary particles each having a monolithic structure, as observed by a suitable microscopic technique, such as scanning electron microscopy (SEM).

[0018] The particles further comprise aluminum and fluorine, and the particles have an atomic ratio of Al to the total amount of Ni, Mn, and / or Co of 1.0 to 7.0. Preferably, the particles have an atomic ratio of Al to the total amount of Ni, Mn, and / or Co of 1.1 to 6.0. Such ratios are determined by XPS analysis, which provides the atomic content of elements in the uppermost layer of the particle at a penetration depth of about 10 nm from the outer edge of the particle. The outer edge of the particle is also referred to as the "surface."

[0019] More preferably, the present invention provides a cathode active material according to the first aspect of the present invention, wherein the cathode active material has an atomic ratio of Al to the total atomic content of Ni, Mn, and / or Co, as determined by XPS analysis, of 1.2 to 4.5. Even more preferably, the present invention provides a cathode active material according to the first aspect of the present invention, wherein the cathode active material has an atomic ratio of Al to the total atomic content of Ni, Mn, and / or Co, as determined by XPS analysis, of 1.7 to 3.5. Preferably, the atomic ratio is 2.0 to 3.5, and more preferably, the atomic ratio is equal to 2.0, 2.2, 2.4, 2.6, 2.8, 3.0, 3.2, 3.4, or any value therebetween.

[0020] Furthermore, the particles have an atomic ratio of F to the total amount of Ni, Mn, and / or Co of 0.5 to 6.0. Preferably, the particles have an atomic ratio of F to the total amount of Ni, Mn, and / or Co of 0.8 to 4.5. Such ratios can also be easily determined by XPS analysis. Preferably, the present invention provides a cathode active material according to the first aspect of the present invention, wherein the atomic ratio of F to the total atomic content of Ni, Mn, and / or Co is 0.6 to 3.0, as determined by XPS analysis. More preferably, the present invention provides a cathode active material according to the first aspect of the present invention, wherein the atomic ratio of F to the total atomic content of Ni, Mn, and / or Co is 1.0 to 2.5, as determined by XPS analysis. Preferably, the atomic ratio is equal to 1.2, 1.4, 1.6, 1.8, 2.0, 2.2, 2.4, or any value therebetween.

[0021] Preferably, the present invention provides a cathode active material according to the first aspect of the present invention, wherein the atomic ratio of Al to F in the cathode active material is 1.00 to 2.50, as determined by XPS analysis. Preferably, the atomic ratio is 1.2 to 2.2, more preferably 1.5 to 2.0, and more preferably, the ratio of Al to F is equal to 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, or any value therebetween.

[0022] In a preferred embodiment, the positive electrode active material is included as a powder. Preferably, the powder has a size of at least 45 μm by at least 60 μm (i.e., at least 2700 μm) as provided by SEM. 2 ), preferably at least 100 μm × at least 100 μm (i.e., at least 10,000 μm 2 A powder is called a single crystal powder if 80% or more of the particles within a field of view have a single crystal morphology. Monolithic particles, single particles, and single crystal particles are synonyms for single crystal particles. Such particles with a single crystal morphology are shown in Figure 1.

[0023] The positive electrode active material for rechargeable batteries according to the present invention has indeed been shown to improve Q in lithium ion batteries. total , thus enabling a reduction in leakage capacity. This is illustrated by EX1 and EX2, the results of which are shown in Table 3. EX1 details a positive electrode active material comprising single-crystalline particles containing aluminum and fluorine elements, where the atomic ratio of Al to the total atomic content of Ni, Mn, and / or Co is 3.28, as determined by XPS analysis, and the atomic ratio of F to the total atomic content of Ni, Mn, and / or Co is 1.86, as determined by XPS analysis. Furthermore, the inventors have found that the Q of the positive electrode active material total It was determined that a synergistic effect of the presence of Al and F in combination with the single crystal morphology of the particles on the SiO2 value was achieved.

[0024] The composition of the positive electrode active material particles is determined by known analytical methods such as ICP-OES (inductively coupled plasma-optical emission spectrometry, hereinafter also referred to as ICP) and IC (ion chromatography) according to the general formula Li 1+a (Ni x Mn y CO z A c D d ) 1-a It can be represented as the subscripts a, x, y, z, a, d in O2.

[0025] Preferably, the present invention provides a cathode active material according to the first aspect of the present invention, wherein the particles have a nickel atomic content of at least 50%, preferably at least 55%, or even at least 60%, relative to the total atomic content of Ni, Mn, and / or Co in the particles, as determined by ICP analysis. Preferably, the particles have a nickel atomic content of at most 99%, more preferably at most 95%. More preferably, the nickel content is at most 90% or at most 85%. Even more preferably, the particles have a nickel atomic content of 60-80%, more preferably 60-75%, or even 60-70%. Particularly preferably, the present invention provides a cathode active material according to the first aspect of the present invention, wherein the particles have a nickel atomic content of 60, 62, 64, 66, 68, 70, 72, or 74%, or any value therebetween. In these preferred embodiments, a synergistic effect between the composition of the surface layer and the single-crystal morphology of the cathode active material on the Qtotal of the resulting battery is observed.

[0026] As will be understood by one of ordinary skill in the art, the atomic content of a given element means what percentage of the total atoms in the claimed compound are atoms of that element.

[0027] Preferably, the present invention provides a cathode active material according to the first aspect of the present invention, wherein the particles have an atomic content of cobalt of at most 50%, preferably at most 30%, or even at most 20%, relative to the total atomic content of Ni, Mn, and / or Co in the particles, as determined by ICP. Preferably, the particles have an atomic content of cobalt of at least 1%, at least 3%, or even at least 5%. The present invention provides a cathode active material according to the first aspect of the present invention, wherein the particles have an atomic content of cobalt of 5, 7, 9, 11, 13, 15, 17, or 19%, or any value therebetween.

[0028] Preferably, the present invention provides a cathode active material according to the first aspect of the present invention, wherein the particles have an atomic content of manganese of at most 50%, preferably at most 30%, or even at most 20%, relative to the total atomic content of Ni, Mn, and / or Co in the particles, as determined by ICP. Preferably, the particles have an atomic content of manganese of at least 1%, at least 3%, or even at least 5%. The present invention provides a cathode active material according to the first aspect of the present invention, wherein the particles have an atomic content of manganese of 5, 7, 9, 11, 13, 15, 17, or 19%, or any value therebetween.

[0029] Preferably, the present invention provides a positive electrode active material according to the first aspect of the present invention, wherein the particles contain Al and F. As measured by ICP, the content of Al and F (hereinafter referred to as A) in the particles relative to the total amount of nickel, cobalt, and / or manganese in the particles is preferably 0.05 to 3.0%, preferably 0.5 to 2.0%.

[0030] Preferably, the A content is A Al +A F where A Al is the Al content in the positive electrode active material particles as determined by ICP measurement, and A F is the content of F in the positive electrode active material particles as determined by ICP measurement. Preferably, A is the content of F in the positive electrode active material particles as determined by ICP measurement relative to the total amount of nickel, cobalt, and / or manganese in the particles. Al is 0.025 to 2.0%, and A F is 0.025 to 2.0%.

[0031] Preferably, the present invention provides an active cathode material according to the first aspect of the present invention, wherein the particles comprise one or more D elements in an amount of up to 10%, more preferably up to 5%, relative to the total atomic content of Ni, Mn, and / or Co in the particles, as measured by ICP. Preferably, the D elements are selected from B, Ba, Ca, Mg, Al, Nb, Sr, Ti, Fe, Mo, W, and Zr, more preferably Al, Mg, Fe, Mo, W, and Zr, and most preferably Al, Mg, W, and Zr.

[0032] Preferably, the present invention provides an active cathode material according to the first aspect of the present invention, wherein the particles comprise lithium, and the molar ratio of lithium to the total molar amount of nickel, manganese, and / or cobalt is 0.95≦Li:Me≦1.10, where Me is the total atomic fraction of Ni, Mn, and / or Co.

[0033] Preferably, the present invention provides a cathode active material according to the first aspect of the present invention, wherein the particles have a median particle size (d50 or D50) of 2 μm to 9 μm as determined by laser diffraction. The median particle size (d50 or D50) can be measured using a Malvern Mastersizer 3000. Preferably, the median particle size is 2 μm to 8 μm, more preferably 3 μm to 7 μm, and most preferably about 4 μm.

[0034] Preferably, the present invention relates to a cathode active material having a leakage capacity Q total The leakage capacity Q is at most 35 mAh / g, preferably at most 30 mAh / g, preferably at most 25 mAh / g, and most preferably at most 20 mAh / g. total is determined by the coin cell test procedure at 80°C using a 1C current definition of 160 mA / g in the 4.4 to 3.0 V / Li metal window range. The test procedure is further described in § 1.5 and is incorporated herein by reference.

[0035] Preferably, the present invention provides a cathode active material according to the first aspect of the present invention, comprising LiF, LiAlO2, and Al2O3, as identified by XPS.

[0036] positive electrode The present invention provides a positive electrode for a lithium-ion secondary battery, comprising a positive electrode active material according to the first aspect of the present invention and a polymer solid electrolyte. The use of such a positive electrode in an SSB has the purpose of improving the capacity of the SSB containing the positive electrode active material by enabling better interfacial contact between the positive electrode active material and the solid electrolyte.

[0037] In the framework of the present invention, the positive electrode is a mixture comprising a solid electrolyte and a positive electrode active material powder.

[0038] Preferably, the positive electrode is prepared by mixing the solid electrolyte and the positive electrode active material powder in a solvent to form a slurry, casting the slurry onto an aluminum foil, followed by removing the solvent by a drying step.

[0039] Preferably, the polymer solid electrolyte is a mixture containing polycaprolactone and lithium bis(trifluoromethanesulfonyl)imide salt.

[0040] Preferably, the positive electrode comprises a polymer solid electrolyte and a positive electrode active material powder, with the ratio of polymer solid electrolyte to positive electrode active material powder being 3:20 to 9:20, more preferably 1:5 to 2:5, and most preferably about 7:25.

[0041] polymer battery In a second aspect, the present invention provides a polymer battery comprising an active cathode material according to the first aspect of the present invention.

[0042] electrochemical cell In a third aspect, the present invention provides an electrochemical cell comprising an active cathode material according to the first aspect of the present invention.

[0043] method In a fourth aspect, the present invention provides a method of making a cathode active material, comprising: mixing a single crystalline mixed metal oxide comprising lithium, nickel, and at least one metal selected from the group consisting of manganese and cobalt with a first Al-containing compound to obtain a first mixture; heating the first mixture at a first heating temperature of at least 500°C and at most 1000°C to obtain a first heat-treated mixture; mixing a fluorine-containing compound and a second Al-containing compound with the first heat treatment mixture to obtain a second mixture; and heating the second mixture at the second heating temperature of at least 200°C and at most 500°C.

[0044] As will be understood by one of ordinary skill in the art, increasing the amount of the first Al-containing compound and / or the second Al-containing compound and / or the fluorine-containing compound will result in a higher atomic ratio of Al and / or F (i.e., a higher amount of Al and / or F will be found in the surface layer positive electrode material) as determined by XPS analysis.

[0045] Preferably, the present invention provides a method according to the fourth aspect of the present invention for making a cathode material according to the first aspect of the present invention, namely, a single crystal mixed metal oxide comprising lithium, nickel and at least one metal selected from the group comprising manganese and cobalt; the nickel atomic content is 50.0% to 95%, preferably 60.0% to 90%, based on the total atomic content of Ni, Mn, and / or Co; the cobalt atomic content is 5.0% to 40%, preferably 5.0% to 30%, based on the total atomic content of Ni, Mn, and / or Co; the manganese atomic content is 0.0% to 70%, preferably 0.5% to 70%, based on the total atomic content of Ni, Mn, and / or Co; The prepared positive electrode active material further contains A and D, A contains Al and F, the Al atomic content is 0.025% to 3%, preferably 0.5% to 2%, based on the total atomic content of Ni, Mn, and / or Co, and the F atomic content is 0.025% to 3%, preferably 0.5% to 2%, based on the total atomic content of Ni, Mn, and / or Co; The D atomic content is 0% to 10%, preferably 0.0% to 5%, based on the total atomic content of Ni, Mn, and / or Co, and D includes at least one element selected from the group consisting of B, Ba, Ca, Mg, Al, Nb, Sr, Ti, Fe, Mo, W, and Zr. The D source can be added during precursor preparation or during the blending step together with the lithium source. For example, the D source can be added to improve the electrochemical properties of the positive electrode active material powder product. The atomic content is determined by ICP.

[0046] Preferably, the present invention provides a method according to the fourth aspect of the present invention, wherein the first Al-containing compound is mixed with the single-crystal lithium transition metal oxide compound and the second Al-containing compound is the same as the first Al-containing compound. Preferably, the present invention provides a method according to the fourth aspect of the present invention, wherein the first and / or second Al-containing compound is Al2O3.

[0047] Preferably, the present invention provides a method for producing an Al-containing compound having a D50<100 nm and a surface area ≥ 50 m 2 / g of nanometric alumina powder.

[0048] Preferably, the present invention provides the method according to the fourth aspect of the present invention, wherein the content of the fluorine-containing polymer in the second mixture is 0.1 to 2.0 wt % based on the total weight of the second mixture. Preferably, the content of the fluorine-containing polymer in the second mixture is 0.1 to 0.5 wt %, more preferably, the content is equal to 0.2, 0.25, 0.3, 0.35, 0.4, or 0.45, or any value therebetween.

[0049] Preferably, the present invention provides a method according to the fourth aspect of the invention, wherein the fluorine-containing polymer is selected from the group comprising PVDF homopolymer, PVDF copolymer, PVDF-HFP polymer (hexafluoropropylene), and PTFE polymer, or a combination of two or more of the foregoing.

[0050] In a fifth aspect, the present invention provides the use of the cathode active material according to the first aspect of the present invention in a battery of any one of a portable computer, a tablet, a mobile phone, an electric vehicle, and an energy storage system. [Example]

[0051] The following examples are intended to further clarify the present invention, but are not intended to limit the scope of the invention.

[0052] 1. Explanation of analysis method 1.1.Inductively Coupled Plasma The composition of the positive electrode active material powder was measured by inductively coupled plasma (ICP) using an Agilent 720 ICP-OES (Agilent Technologies, https: / / www.agilent.com / cs / library / brochures / 5990-6497EN%20720-725_ICP-OES_LR.pdf). One gram of powder sample was dissolved in 50 mL of high-purity hydrochloric acid (at least 37 wt.% HCl based on the total weight of the solution) in an Erlenmeyer flask. The flask was covered with a watch glass and heated on a hot plate at 380 °C until the powder was completely dissolved. After cooling to room temperature, the solution from the Erlenmeyer flask was poured into a first 250 mL volumetric flask. The first volumetric flask was then filled to the 250 mL mark with deionized water, followed by a thorough homogenization procedure (first dilution). Pipette an appropriate amount of the solution from the first volumetric flask and transfer it to a second 250 mL volumetric flask for the second dilution. Fill the second volumetric flask up to the 250 mL mark with the internal standard element and 10% hydrochloric acid, then homogenize. Finally, use this solution for ICP measurement.

[0053] 1.2.SEM (Scanning Electron Microscope) Analysis The morphology of the positive electrode active material is analyzed by scanning electron microscopy (SEM). -5 This is performed using a JEOL JSM7100F under a high vacuum environment of 100 Pa.

[0054] 1.3.Surface area analysis The specific surface area of ​​the powder is analyzed by the Brunauer-Emmett-Teller (BET) method using a Micromeritics Tristar 3000. To remove adsorbed species, the powder sample is heated at 300°C for 1 hour before the measurement under nitrogen (N2) gas. The dried powder is placed in a sample tube. The sample is then degassed at 30°C for 10 minutes. The nitrogen adsorption test is performed in the instrument at 77K. The m is determined from the nitrogen adsorption / desorption isotherm. 2The total specific surface area of ​​the sample in units of / g is derived.

[0055] 1.4.Particle size distribution The particle size distribution (PSD) of the cathode active material powders was measured by dispersing each powder sample in aqueous medium using a Malvern Mastersizer 3000 equipped with a Hydro MV wet dispersion accessory (https: / / www.malvernpananalytical.com / en / products / product-range / mastersizer-range / mastersizer-3000#overview). Sufficient ultrasonic irradiation and stirring were applied to improve powder dispersion, and appropriate surfactants were 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.

[0056] 1.5. Polymer Cell Test 1.5.1. Preparation of polymer cells 1.5.1.1. Preparation of Solid Polymer Electrolyte (SPE) The solid polymer electrolyte (SPE) is prepared according to the following method. Step 1) Polyethylene oxide (PEO with a molecular weight of 1,000,000, Alfa Aesar) in 99.8 wt% anhydrous acetonitrile (Aldrich https: / / www.sigmaaldrich.com / catalog / product / sial / 271004?lang=ko®ion=KR&gclid=EAIaIQobChMIwcrB0dDL6AIVBbeWCh0ieAXREAAYASAAEgJCa_D_BwE) https: / / www.alfa.co.kr / AlfaAesarApp / faces / adf.task-flow?adf.tfId=ProductDetailsTF&adf.tfDoc= / WEB-INF / ProductDetailsTF.xml&ProductId=043678&_afrLoop=1010520209597576&_afrWindowMode=0&_afrWindowId=null) and lithium bis(trifluoromethanesulfonyl)imide salt (LiTFSI, Soulbrain Co., Ltd.) were mixed for 30 minutes using a mixer at 2000 revolutions per minute (rpm). The molar ratio of ethylene oxide to lithium was 20. Step 2) Pour the mixture from step 1) into a Teflon dish and let it dry at 25°C for 12 hours. Step 3) Remove the dried SPE from the dish and punch out the dried SPE to obtain an SPE disk with a thickness of 300 μm and a diameter of 19 mm.

[0057] 1.5.1.2. Preparation of the Catholyte Electrode The catholyte electrode is prepared according to the following method. Step 1) Prepare a polymer electrolyte mixture containing a solution of polycaprolactone (PCL with a molecular weight of 80,000, Sigma-Aldrich https: / / www.sigmaaldrich.com / catalog / product / aldrich / 440744) in 99.7 wt% anhydrous anisole (Sigma-Aldrich, https: / / www.sigmaaldrich.com / catalog / product / aldrich / 440744) and lithium bis(trifluoromethanesulfonyl)imide salt (LiTFSI, Sigma-Aldrich, https: / / www.sigmaaldrich.com / catalog / product / aldrich / 544094) in acetonitrile. The mixture has a weight ratio of PCL:LiTFSI of 74:26. Step 2) The polymer electrolyte mixture prepared in Step 1), the positive electrode active material, and the conductive powder (Super P, Timcal (Imerys Graphite & Carbon), http: / / www.imerys-graphite-and-carbon.com / wordpress / wp-app / uploads / 2018 / 10 / ENSACO-150-210-240-250-260-350-360-G-ENSACO-150-250-P-SUPER-P-SUPER-P-Li-C-NERGY-SUPER-C-45-65-T_V-2.2_-USA-SDS.pdf) were mixed in an acetonitrile solution in a weight ratio of 21:75:4 to prepare a slurry mixture. Mixing was performed using a homogenizer at 5000 rpm for 45 minutes. Step 3) Cast the slurry mixture from step 2) onto one side of a 20 μm thick aluminum foil with a coater gap of 100 μm. Step 4) The slurry-cast foil is dried at 30°C for 12 hours and subsequently punched out to obtain a 14 mm diameter catholyte electrode.

[0058] 1.5.1.3. Polymer Cell Assembly Assemble the coin-shaped polymer cell in an argon-filled glove box from bottom to top: 2032 coin cell can, catholyte electrode prepared in section 1.5.1.2, SPE prepared in section 1.5.1.1, gasket, Li anode, spacer, wave spring, and cell cap. Then, completely seal the coin cell to prevent electrolyte leakage.

[0059] Test Method Each coin-shaped polymer cell was cycled at 80 °C using a Toscat-3100 computer-controlled constant current cycling station (Toyo System, http: / / www.toyosystem.com / image / menu3 / toscat / TOSCAT-3100.pdf). The coin cell test procedure used a 1 C current definition of 160 mA / g in the 4.4–3.0 V / Li metal window range, according to the following schedule: Step 1) Charge in constant current mode at a C rate of 0.05 with an end condition of 4.4V, followed by a 10 minute rest. Step 2) Discharge in constant current mode at a C rate of 0.05 with an end condition of 3.0 V, followed by a 10 minute rest. Step 3) Charge in constant current mode at a C rate of 0.05 with an end condition of 4.4V. Step 4) Switch to constant voltage mode and maintain 4.4V for 60 hours. Step 5) Discharge in constant current mode at a C rate of 0.05 with an end condition of 3.0V.

[0060] Q total Q is defined as the total leakage capacitance at high voltage and temperature in step 4) according to the described test method. total A small value indicates that the positive electrode active material powder is highly stable during high temperature operation.

[0061] 1.6.X-ray photoelectron spectroscopy (XPS) 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 measurements, signals are obtained 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.

[0062] For the surface analysis of the positive electrode active material powder particles, XPS measurements are performed using a Thermo K-α+ spectrometer (Thermo Scientific, https: / / www.thermofisher.com / order / catalog / product / IQLAADGAAFFACVMAHV).

[0063] Monochromated Al Kα radiation (hυ = 1486.6 eV) is used with a spot size of 400 μm and a measurement angle of 45°. A broad 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. At least 10 precise narrow scans at 50 eV are then performed for each identified element to determine the exact surface composition.

[0064] Curve fitting was performed in CasaXPS version 2.3.19PR1.0 (Casa Software, http: / / www.casaxps.com / ) using Shirley-type background processing and Scofield sensitivity coefficients. Fitting parameters follow Table 1a. The lineshape GL(30) is a Gaussian / Lorentzian product formula with a 70% Gaussian line and a 30% Lorentzian line. LA(α,β,m) is the asymmetric lineshape, where α and β define the tail broadening of the peak and m defines the width.

[0065] [Table 1]

[0066] Set constraints for each peak defined according to Table 1b for the Al peak within the fit range of 64.1 ± 0.1 eV to 78.5 ± 0.1 eV. The Ni 3p peak is not included in the quantification. Table 1b. XPS fit constraints for the Al 2p peak fit.

[0067] [Table 2]

[0068] The Al and F surface content is expressed by dividing the atomic content of Al and F, respectively, in the surface layer of the particle by the total content of Ni, Mn, and / or Co in that surface layer, and is calculated as follows:

[0069]

number

[0070] 2. Examples and Comparative Examples Comparative Example 1 General formula Li 1.01 (Ni 0.63 Mn 0.22 Co 0.15 ) 0.99 The single-crystalline cathode active material powder labeled CEX1 with O2 is obtained through a solid-state reaction between a lithium source and a nickel-based transition metal source. The method is carried out as follows: Step 1) Preparation of transition metal oxide hydroxide precursor: Metal composition Ni 0.63 Mn 0.22 Co 0.15 A nickel-based transition metal oxide hydroxide powder (TMH1) having the formula (I) is prepared by co-precipitation in a large-scale continuous stirred tank reactor (CSTR) containing mixed nickel manganese cobalt sulfate, sodium hydroxide, and ammonia. Step 2) First Mixing: The TMH1 prepared in step 1) is mixed with Li2CO3 in an industrial blender to obtain a first mixture with a lithium to metal ratio of 0.85. Step 3) First firing: The first mixture from step 2) is fired in a dry air atmosphere at 900°C for 10 hours to obtain a first fired cake. The first fired cake is pulverized to obtain a first fired powder. Step 4) Second Mixing: The first calcined powder from step 3) is mixed with LiOH in an industrial blender to obtain a second mixture with a lithium to metal ratio of 1.05. Step 5) Second calcination: The second mixture from step 4) is calcined at 930°C for 10 hours in dry air, followed by crushing (bead milling) and sieving methods to obtain the second calcined powder. Step 6) Third Mixing: The second calcined powder from step 5) is mixed with, for example, 2 mol% Co from Co3O4 powder and 5 mol% LiOH relative to the total molar content of Ni, Mn, and / or Co in an industrial blender to obtain a third mixture. Step 7) Third Firing: The third mixture from step 6) is sintered in dry air at 775°C for 12 hours to produce a third fired powder labeled CEX1. The powder has a median particle size of 6.5 μm as determined by laser diffraction measured on a Malvern Mastersizer 3000.

[0071] Example 1 The surface-modified single-crystal positive electrode active material EX1 is prepared according to the following method. Step 1) Mix 1 kg of CEX1 powder with 2 grams of alumina (Al2O3) nanopowder at 1000 rpm for 30 minutes. Step 2) The mixture obtained from step 1) is calcined in a furnace under a flow of oxidizing atmosphere at 750° C. for 10 hours. Step 3) Mix 1 kg of powder from step 2) with 2 grams of alumina (Al2O3) nanopowder and 3 grams of polyvinylidene fluoride (PVDF) powder at 1000 rpm for 30 minutes. Step 4) The mixture obtained from step 3) is calcined in a furnace under a flow of oxidizing atmosphere at 375°C for 5 hours to produce a calcined powder labeled EX1. The powder has a median particle size of 6.4 μm as determined by laser diffraction measured on a Malvern Mastersizer 3000.

[0072] Comparative Example 2 The single-crystalline cathode active material, designated CEX2, is obtained through a solid-state reaction between a lithium source and a nickel-based transition metal source. The method is carried out as follows: Step 1) Preparation of transition metal oxide hydroxide precursor: Metal composition Ni 0.86 Mn 0.07 Co 0.07 Nickel-based transition metal oxide hydroxide powder (TMH2) having the formula (I) is prepared by co-precipitation in a large-scale continuous stirred tank reactor (CSTR) containing mixed nickel manganese cobalt sulfate, sodium hydroxide, and ammonia. Step 2) Heating: The TMH2 prepared in step 1) is heated at 400°C for 7 hours in an oxidizing atmosphere to produce a heated powder. Step 3) First Mixing: The heated powder prepared in step 2) is mixed with LiOH in an industrial blender to obtain a first mixture with a lithium to metal ratio of 0.96. Step 4) First calcination: The first mixture from step 3) is calcined at 890°C for 11 hours in an oxidizing atmosphere, followed by wet bead milling and sieving to obtain the first calcined powder. Step 5) Second Mixing: The first calcined powder from step 4) is mixed with LiOH in an industrial blender to obtain a second mixture with a lithium to metal ratio of 0.99. Step 6) Second calcination: The second mixture from step 5) is calcined in oxidizing air at 760°C for 10 hours, followed by grinding and sieving to obtain a second calcined powder labeled CEX2. The powder has a median particle size of 4.5 μm as determined by laser diffraction measured on a Malvern Mastersizer 3000.

[0073] Example 2 Prepare surface-modified single-crystalline cathode active material EX2 in the same manner as EX1, except that CEX2 is used instead of CEX1 in the mixing of step 1. The powder has a median particle size of 4.5 μm as determined by laser diffraction measured on a Malvern Mastersizer 3000.

[0074] Comparative Example 3 The polycrystalline cathode active material, designated CEX3A, is obtained through a solid-state reaction between a lithium source and a nickel-based transition metal source. The method is carried out as follows: Step 1) Preparation of transition metal oxide hydroxide precursor: Metal composition Ni 0.625 Mn 0.175 Co 0.20 Nickel-based transition metal oxide hydroxide powder (TMH3) with an average particle size (D50) of 10.1 μm is prepared by co-precipitation in a large-scale continuous stirred tank reactor (CSTR) containing mixed nickel manganese cobalt sulfate, sodium hydroxide, and ammonia. Step 2) First Mixing: The TMH3 prepared in step 1) is mixed with LiOH in an industrial blender to obtain a first mixture with a lithium to metal ratio of 1.03. Step 3) First firing: The first mixture from step 2) is fired in a dry air atmosphere at 835°C for 10 hours to obtain a first fired cake. The first fired cake is pulverized to obtain a first fired powder. Step 4) Second Mixing: The first calcined powder from step 3) is mixed with LiOH in an industrial blender to obtain a second mixture with a lithium to metal ratio of 1.03. Step 5) Second calcination: The second mixture from step 4) is calcined in dry air at 830°C for 10 hours, followed by grinding and sieving to obtain a second calcined powder labeled CEX3A. The powder has a median particle size of 9.1 μm as determined by laser diffraction measured on a Malvern Mastersizer 3000.

[0075] A surface-modified polycrystalline positive electrode active material CEX3B is prepared in the same manner as in EX1, except that CEX3A is used instead of CEX1 in the mixing of step 1).

[0076] [Table 3]

[0077] [Table 4]

[0078] Table 2 summarizes the compositions and surface treatments of the examples and comparative examples. Table 3 summarizes the Q values ​​of the examples and comparative examples. total It summarizes the values.

[0079] First, EX1 has a significantly lower Q compared to CEX1. total The same observation was also made for CEX2 and CEX3B compared to CEX2 and CEX3A, respectively. This observation indicates that the surface-modified cathode active material powder according to the present invention has better electrochemical performance. total A small value indicates that the positive electrode active material powder is highly stable when a high voltage is applied at a high temperature.

[0080] Second, it is observed that the surface-modified cathode active material powder with a single crystal morphology is more effective than the polycrystalline morphology. total The improvement in Q was 58.3%, while the improvement in Q from CEX3A with polycrystalline morphology to CEX3B was 58.3%. total The improvement in Q is 23.7%. total In order to achieve the object of the present invention, a synergistic effect between the surface treatment and the single crystal morphology is required.

[0081] Third, the surface treatment was also performed on the positive electrode active material powder in EX2, which has a Ni / Me content of 0.86. total is 32.2mAh / g, which is the Q total Much lower than that.

[0082] Figure 2 shows the XPS spectrum of the Al 2p and F 1s peaks of EX2. The Al peak at a binding energy of approximately 73.8 eV corresponds to the LiAlO2 compound present on the surface of the positive electrode active material (Chem. Mater. Vol. 21, No. 23, pp. 5607-5616, 2009). The F peak at a binding energy of approximately 685.0 eV corresponds to the LiF compound present on the surface of the positive electrode active material (Moulder, JF, Handbook of XPS, Perkin-Elmer, 1992).

[0083] The results show that the Q between the composition of the surface layer and the morphology of the positive electrode active material total The synergistic effect on the surface of the cellulose acetate solution is shown graphically in Figure 3. B and A represent the pre- and post-surface treatment values, respectively, on the x-axis.

Claims

1. A positive electrode active material for a rechargeable battery, comprising lithium, oxygen, nickel, and at least one metal selected from the group consisting of manganese and cobalt, 80% or more of the particles of the positive electrode active material have a single crystal morphology within a 45 μm × 60 μm field of view provided by scanning electron microscope (SEM) measurement; The single crystal form is a form of a single primary particle having a monolithic structure or a form of secondary particles consisting of less than five primary particles each having a monolithic structure, as observed with a scanning electron microscope; The positive electrode active material is i) further comprising aluminum, wherein the atomic ratio of Al to the total amount of Ni, Mn, and Co is 1.0 to 7.0 as determined by XPS analysis; and ii) A positive electrode active material for a rechargeable battery, further comprising fluorine, wherein the atomic ratio of F to the total amount of Ni, Mn, and Co is 0.5 to 6.0, as determined by XPS analysis.

2. The positive electrode active material is i) comprising aluminum, wherein the atomic ratio of Al to the total amount of Ni, Mn, and Co is 1.2 to 4.5, as determined by XPS analysis; and ii) The positive electrode active material according to claim 1, which contains fluorine and has an atomic ratio of F to the total amount of Ni, Mn, and Co of 0.6 to 3.0, as determined by XPS analysis.

3. 3. The cathode active material according to claim 1, wherein the cathode active material has an atomic ratio of Al to the total amount of Ni, Mn, and Co of 1.7 to 3.5, as determined by XPS analysis.

4. 4. The cathode active material according to claim 1, wherein the cathode active material has an atomic ratio of F to the total amount of Ni, Mn, and Co of 1.5 to 2.5, as determined by XPS analysis.

5. A positive electrode active material described in any one of claims 1 to 4, wherein the particles of the positive electrode active material have an atomic content of nickel of 50% to 95% relative to the total atomic content of Ni, Mn, and Co in the particles, as determined by ICP.

6. 6. The cathode active material of claim 1, wherein the particles of the cathode active material have an atomic content of Al of 0.05% to 3.00%, relative to the total atomic content of Ni, Mn, and Co in the particles, as determined by ICP.

7. 7. The cathode active material of claim 1, wherein the particles of the cathode active material have an atomic content of Co of 5.00% to 25.00%, relative to the total atomic content of Ni, Mn, and Co in the particles, as determined by ICP.

8. 8. The cathode active material according to claim 1, wherein the particles of the cathode active material have an atomic content of Mn of 0.00% to 70.00%, relative to the total atomic content of Ni, Mn, and Co in the particles, as determined by ICP.

9. 9. The cathode active material of claim 1, wherein the particles of the cathode active material have a median particle size d50 of 2 μm to 9 μm as determined by laser diffraction.

10. Leakage capacity Q up to 35mAh / g ｔｏｔａｌ and the leakage capacity Q ｔｏｔａｌ is determined by a coin cell test procedure at 80° C. using a 1 C current definition of 160 mA / g in the 4.4 to 3.0 V / Li metal window range.

11. A positive electrode for a lithium ion secondary battery comprising a positive electrode active material and a polymer solid electrolyte, wherein the positive electrode active material is the positive electrode for a lithium ion secondary battery according to any one of claims 1 to 10.

12. A polymer battery comprising the positive electrode active material according to any one of claims 1 to 10.

13. An electrochemical cell comprising the positive electrode active material according to any one of claims 1 to 10.

14. A method for producing the positive electrode active material according to any one of claims 1 to 10, comprising: mixing a single crystal mixed metal oxide comprising lithium, nickel, and at least one metal selected from the group consisting of manganese and cobalt with a first Al-containing compound to obtain a first mixture; heating the first mixture at a first heating temperature of at least 500°C and at most 1000°C to obtain a first heat-treated mixture; mixing a fluorine-containing compound and a second Al-containing compound with the first heat treatment mixture to obtain a second mixture; heating the second mixture at a second heating temperature of at least 200°C and at most 500°C.

15. Use of the positive electrode active material according to any one of claims 1 to 10 in a battery of any one of a portable computer, a tablet, a mobile phone, an electric vehicle, and an energy storage system.

16. 6. The cathode active material of claim 5, wherein the particles have an atomic content of nickel of 60% to 85%, relative to the total atomic content of Ni, Mn, and Co in the particles, as determined by ICP.

17. The leakage capacity Q of up to 20 mAh / g ｔｏｔａｌ The positive electrode active material according to claim 10 , having

18. 12. The positive electrode for a lithium ion secondary battery according to claim 11, wherein the polymer solid electrolyte comprises polycaprolactone.

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