Positive electrode active material for a rechargeable battery pack

Abstract

The present invention provides a positive electrode active oxide material for a rechargeable battery pack, the positive electrode active oxide material comprising lithium, nickel, and at least one metal selected from manganese and cobalt, whereby the positive electrode active 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 from 1.0 to 7.0, and wherein the surface layer has an atomic ratio of F to the total amount of Ni, Mn, and / or Co of from 0.5 to 6.0, as determined by XPS analysis.

Description

Technical Field

[0001] The present invention relates to a positive electrode active oxide material (hereinafter also referred to as a positive electrode active material) for a rechargeable battery pack, particularly for a solid-state battery pack (SSB) application, the positive electrode active oxide material comprising lithium, oxygen, nickel, and at least one metal selected from manganese and cobalt.

[0002] More specifically, the present invention relates to single-crystalline positive electrode active material powder microparticles of the positive electrode active material.

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

[0004] Such single-crystalline positive electrode active material powders have been known, for example, from the document WO 2019 / 185349. The document WO2019 / 185349 discloses a method for preparing a single-crystalline positive electrode active material powder. The morphology is generally preferred in SSB applications because the monolithic morphology ensures good surface contact between the solid-state electrolyte and the positive electrode active material particles. However, an undesired side reaction at the interface between the positive electrode active material particles and the solid-state electrolyte deteriorates the electrochemical characteristics. Side reactions (such as metal dissolution) are particularly severe in polymer SSBs operated at higher temperatures, resulting in an undesired high leakage capacity (Q 总 ).

[0005] An object of the present invention is to provide a positive electrode active material powder for a rechargeable battery pack, the positive electrode active material powder having a reduced leakage current, which enhances the durability and performance of the battery pack unit. More specifically, an object of the present invention is to provide a positive electrode active material for a lithium-ion battery pack, particularly for an SSB application, the positive electrode active material having a total leakage capacity (Q 总 ) of at most 35 mAh / g or even at most 20 mAh / g, as determined by the analysis method of the present invention. Summary of the Invention

[0006] This object is achieved by providing a positive electrode active material for a rechargeable battery pack according to claim 1. It has indeed been observed that an improved Qtotal is achieved in a lithium-ion battery pack using the positive electrode active material powder according to the present invention, and thus a reduced leakage capacity is achieved, as shown in EXI and EX2 and supported by the results provided in Table 3. EXI teaches a positive electrode active material comprising single crystal particles containing aluminum and fluorine elements, wherein 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] Furthermore, the present invention provides: a polymer battery pack comprising the positive electrode active material according to the first aspect of the present invention; an electrochemical cell comprising the positive electrode active material according to the first aspect of the present invention; a method for manufacturing the positive electrode active material according to the first aspect of the present invention; and the use of the positive electrode active material according to the first aspect of the present invention in a battery pack of any one of a portable computer, a tablet computer, a mobile phone, an electric vehicle, and an energy storage system. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] By further guidance, including the drawings, the teachings of the present invention can be better understood. The drawings are intended to assist in the description of the present invention and are not intended as a limitation of the presently disclosed invention. The drawings and symbols contained therein have the meanings commonly understood by those of ordinary skill in the art to which the present invention pertains.

[0009] Figure 1 A scanning electron microscope (SEM) image of the positive electrode active material powder having a single crystal morphology according to EXI is shown.

[0010] Figure 2 An X-ray photoelectron spectroscopy (XPS) graph is shown, which shows the presence of Al2p peaks and FIs peaks in EX2 compared to CEX2.

[0011] Figure 3 The effect of surface treatment on the Q 总 value of the positive electrode active materials of EXI and EX2 is shown compared to CEX1, CEX2, CEX3A, and CEX3B. The X-axis is the surface treatment, where B represents before the surface treatment and A represents after the surface treatment. DETAILED DESCRIPTION

[0012] Unless otherwise defined, all terms (including technical and scientific terms) used in the disclosure of the present invention have the meanings commonly understood by one of ordinary skill in the art to which this invention belongs. Further guidance is provided, including term definitions, to better understand the teachings of the present invention.

[0013] As used herein, the following terms have the following meanings:

[0014] It should be understood that when an element is referred to as being "on" another element, it can be directly on the other element or there can be intervening elements between them. In contrast, when an element is referred to as being "directly on" another element, there are no intervening elements.

[0015] It should be understood that although the terms "first", "second", "third", etc. may be used herein to describe various elements, components, regions, layers, and / or sections, these elements, components, regions, layers, and / or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer, or section from another. Thus, the "first element", "component", "region", "layer", or "section" discussed below can be referred to as a second element, component, region, layer, or section without departing from the teachings herein.

[0016] The terms used herein are for the purpose of describing particular embodiments only and are 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 context clearly indicates otherwise. "At least one" should not be construed as limiting "one" or "a / an".

[0017] It will be further understood that when used in this specification, the terms "comprises" and / or "comprising" specify the presence of the stated features, structures, regions, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, structures, regions, integers, steps, operations, elements, components, and / or groups thereof.

[0018] Spatial relative terms, such as "beneath", "below", "lower", "above", "upper", etc., may be used herein for convenience of description to describe the relationship of one element or feature to another element or feature as shown in the figures. It should be understood that spatial 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 is turned over, an element described as "beneath" or "below" another element or feature will then be oriented "above" the other element or feature. Thus, the exemplary term "beneath" can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations), and the spatial relative descriptors used herein are to be interpreted accordingly.

[0019] As used herein, "about", when referring to a measurable value such as a parameter, quantity, time duration, etc., is intended to encompass variations of + / - 20% or less, preferably + / - 10% or less, more preferably + / - 5% or less, even more preferably + / - 1% or less, and still more preferably + / - 0.1% or less from the specified value, and such variations are suitable for carrying out the invention as disclosed. However, it should be understood that the value itself modified by the term "about" is also specifically disclosed.

[0020] Numerical ranges expressed by endpoints include all numbers and fractions contained within that range, as well as the recited endpoints. All percentages are to be understood as weight percentages abbreviated as "wt%" or volume percentages abbreviated as "vol%", unless otherwise defined or unless a different meaning is obvious to the person skilled in the art from their use and the context in which they are used.

[0021] Positive electrode active material

[0022] In a first aspect, the present invention provides a positive electrode active material for a rechargeable battery pack, the positive electrode active material comprising lithium, nickel, and at least one metal selected from manganese and cobalt. The present invention particularly relates to a positive electrode active material in which the particles have a single crystal morphology. In the context of the present invention, a single crystal morphology refers to the morphology of a single primary particle having a monolithic structure or a secondary particle composed of fewer than five primary particles, each primary particle having a monolithic structure, as observed by appropriate microscopy techniques such as scanning electron microscopy (SEM).

[0023] The particles further comprise aluminum and fluorine, whereby 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. This ratio is determined by XPS analysis. XPS analysis provides the atomic content of the elements in the outermost layer of the particles, where the penetration depth from the outer edge of the particles is about 10 nm. The outer edge of the particles is also referred to as the "surface".

[0024] More preferably, the present invention provides a positive electrode active material according to the first aspect of the present invention, wherein the positive electrode active material has an atomic ratio of Al to the total atomic content of Ni, Mn and / or Co of 1.2 to 4.5, as determined by XPS analysis. Even more preferably, the present invention provides a positive electrode active material according to the first aspect of the present invention, wherein the positive electrode active material has an atomic ratio of Al to the total atomic content of Ni, Mn and / or Co of 1.7 to 3.5, as determined by XPS analysis. Preferably, the atomic ratio is between 2.0 and 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.

[0025] In addition, 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. This ratio is also easily determined by XPS analysis. Preferably, the present invention provides a positive electrode active material according to the first aspect of the present invention, wherein the positive electrode active material has an atomic ratio of F to the total atomic content of Ni, Mn and / or Co of 0.6 to 3.0, as determined by XPS analysis. More preferably, the present invention provides a positive electrode active material according to the first aspect of the present invention, wherein the positive electrode active material has an atomic ratio of F to the total atomic content of Ni, Mn and / or Co of 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.

[0026] Preferably, the present invention provides a positive electrode active material according to the first aspect of the present invention, wherein in the positive electrode active material, the atomic ratio of Al to F is 1.00 to 2.50, as determined by XPS. Preferably, the atomic ratio is between 1.2 and 2.2, more preferably between 1.5 and 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.

[0027] In a preferred embodiment, the positive electrode active material is contained as a powder. Preferably, a powder is referred to as a single crystal powder if the following conditions are provided by SEM measurement: 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. Monolithic particles, integral particles, and single crystal particles are synonyms for single crystal particles. Such particles with a single crystal morphology are shown in Figure 1 middle.

[0028] The positive electrode active material for a rechargeable battery according to the present invention does allow Q in a lithium ion battery to be 总 This is shown by EXI and EX2, and the results are provided in Table 3. EXI details a positive electrode active material comprising single crystal particles containing aluminum and fluorine elements, wherein 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. In addition, the inventors have determined that the combination of the presence of Al and F and the single crystal morphology of the particles has an effect on the Q of the positive electrode active material. 总 The synergy of value.

[0029] The composition of the positive electrode active material particles can be expressed in the general formula Li according to the stoichiometry of the elements 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). 1+a (Ni x Mn y CO z A c D d ) 1-a O2 is represented by indices a, x, y, z, a, and d.

[0030] Preferably, the present invention provides a positive electrode active material according to the first aspect of the present invention, wherein the particles have a nickel atom 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. Preferably, the particles have a nickel atom content of up to 99%, and more preferably up to 95% as described above. More preferably, the nickel content is up to 90% or up to 85%. Even more preferably, the particles have a nickel atom content of 60% to 80%, more preferably 60% to 75%, or even 60% to 70%. Particularly preferably, the present invention provides a positive electrode material according to the first aspect of the present invention, wherein the particles have a nickel atom content of 60%, 62%, 64%, 66%, 68%, 70%, 72%, or 74%, or any value therebetween. In these preferred embodiments, a synergistic effect on Q total of the resulting battery pack was observed between the composition of the surface layer and the single crystal morphology of the positive electrode active material.

[0031] As will be understood by those skilled in the art, the atomic content of a given element means what percentage of all the atoms in the claimed compound are atoms of that element.

[0032] Preferably, the present invention provides a positive electrode active material according to the first aspect of the present invention, wherein the particles have a cobalt atom content 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 a cobalt atom content of at least 1%, at least 3%, or even at least 5% as described above. The present invention provides a positive electrode material according to the first aspect of the present invention, wherein the particles have a cobalt atom content of 5%, 7%, 9%, 11%, 13%, 15%, 17%, or 19%, or any value therebetween.

[0033] Preferably, the present invention provides a positive electrode active material according to the first aspect of the present invention, wherein the particles have a manganese atom content 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 a manganese atom content of at least 1%, at least 3%, or even at least 5% as described above. The present invention provides a positive electrode material according to the first aspect of the present invention, wherein the particles have a manganese atom content of 5%, 7%, 9%, 11%, 13%, 15%, 17%, or 19%, or any value therebetween.

[0034] 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. The content of Al and F (hereinafter referred to as A) in the particles is preferably between 0.05% and 3.0%, preferably between 0.5% and 2.0%, as measured by ICP, relative to the total amount of nickel, cobalt, and / or manganese in the particles.

[0035] Preferably, the A content is equal to A Al +A F , where A Al is the Al content in the positive electrode active material particles (determined as measured by ICP), and A F is the F content in the positive electrode active material particles (determined as measured by ICP). Preferably, relative to the total amount of nickel, cobalt, and / or manganese in the particles, A Al is between 0.025% and 2.0%, and A F is between 0.025% and 2.0%, as measured by ICP.

[0036] Preferably, the present invention provides a positive electrode active material according to the first aspect of the present invention, wherein the particles contain one or more D 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 is selected from: B, Ba, Ca, Mg, Al, Nb, Sr, Ti, Fe, Mo, W, and Zr, and more preferably from: Al, Mg, Fe, Mo, W, and Zr, and most preferably from: Al, Mg, W, and Zr.

[0037] Preferably, the present invention provides a positive electrode active material according to the first aspect of the present invention, wherein the particles contain lithium, whereby 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.

[0038] Preferably, the present invention provides a positive electrode 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 between 2 μm and 8 μm, more preferably between 3 μm and 7 μm, and most preferably about 4 μm.

[0039] Preferably, the present invention provides a positive electrode active material according to the first aspect of the present invention, wherein the positive electrode active material has a leakage capacity Q of 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. 总 The leakage capacity Q 总 is determined by a button cell test procedure at 80 °C within the 4.4 - 3.0 V / Li metal window range using a 1C current definition of 160 mA / g. This test procedure is further described in §1.5 and is incorporated herein by reference.

[0040] Preferably, the present invention provides a positive electrode active material according to the first aspect of the present invention, the positive electrode active material comprising LiF, LiAlO₂, and Al₂O₃, as identified by XPS.

[0041] Positive electrode

[0042] The present invention provides a positive electrode for a lithium-ion secondary battery pack, the positive electrode comprising a positive electrode active material according to the first aspect of the present invention and a polymer solid electrolyte. The purpose of using such a positive electrode in an SSB is to improve the capacity of the SSB comprising the positive electrode material by allowing better interfacial contact between the positive electrode active material and the solid electrolyte.

[0043] In the framework of the present invention, the positive electrode is a mixture comprising a solid electrolyte and positive electrode active material powder.

[0044] Preferably, the positive electrode is manufactured by: mixing the solid electrolyte and positive electrode active material powder in a solvent to form a slurry and casting the slurry onto an aluminum foil, followed by a drying step to remove the solvent.

[0045] Preferably, the polymer solid electrolyte is a mixture comprising polycaprolactone and lithium bis(trifluoromethanesulfonyl)imide salt.

[0046] Preferably, the positive electrode comprises a polymer solid electrolyte and positive electrode active material powder, wherein the ratio of polymer solid electrolyte:positive electrode active material powder is between 3:20 and 9:20, more preferably between 1:5 and 2:5, and most preferably about 7:25.

[0047] Polymer battery pack

[0048] In a second aspect, the present invention provides a polymer battery pack comprising a positive electrode active material according to the first aspect of the present invention.

[0049] Electrochemical cell

[0050] In a third aspect, the present invention provides an electrochemical cell comprising a positive electrode active material according to the first aspect of the present invention.

[0051] Method

[0052] In a fourth aspect, the present invention provides a method for manufacturing a positive electrode active material, the method comprising the steps of:

[0053] - Mixing a single crystal mixed metal oxide with a first Al-containing compound to obtain a first mixture, the single crystal mixed metal oxide comprising lithium, nickel, and at least one metal selected from manganese and cobalt;

[0054] - 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;

[0055] - Mixing a fluorine-containing compound and a second Al-containing compound with the first heat-treated mixture to obtain a second mixture;

[0056] - Heating the second mixture at a second heating temperature of at least 200 °C and at most 500 °C.

[0057] As will be understood by those skilled 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 results in a higher atomic ratio of Al and / or F (i.e., a higher amount of Al and / or F is found in the surface layer of the positive electrode material), as determined by XPS analysis.

[0058] Preferably, the present invention provides a method for manufacturing a positive electrode material according to the first aspect of the present invention according to the fourth aspect of the present invention. That is, a single crystal mixed metal oxide comprising lithium, nickel, and at least one metal selected from manganese and cobalt, wherein:

[0059] - The nickel atomic content is between 50.0% and 95%, preferably between 60.0% and 90%, relative to the total atomic content of Ni, Mn, and / or Co,

[0060] - The cobalt atomic content is between 5.0% and 40%, preferably between 5.0% and 30%, relative to the total atomic content of Ni, Mn, and / or Co,

[0061] - The manganese atomic content is between 0.0% and 70%, preferably between 0.5% and 70%, relative to the total atomic content of Ni, Mn, and / or Co,

[0062] And the manufactured positive electrode active material further comprises A and D, wherein:

[0063] - A contains Al and F, wherein the Al atomic content is between 0.025% and 3%, preferably between 0.5% and 2%, relative to the total atomic content of Ni, Mn, and / or Co, and wherein the F atomic content is between 0.025% and 3%, preferably between 0.5% and 2%, relative to the total atomic content of Ni, Mn, and / or Co,

[0064] - The D atomic content is between 0% and 10%, preferably between 0.0% and 5%, relative to the total atomic content of Ni, Mn, and / or Co, where D contains at least one element selected from B, Ba, Ca, Mg, Al, Nb, Sr, Ti, Fe, Mo, W, and Zr, and the D source can be added together with the lithium source in the preparation of the precursor or in the blending step. For example, a D source can be added to improve the electrochemical characteristics of the positive electrode active material powder product.

[0065] - And wherein the atomic content is defined by ICP.

[0066] 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, whereby 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 the second Al-containing compound is Al2O3.

[0067] Preferably, the present invention provides a method according to the fourth aspect of the present invention, wherein the first and / or the second Al-containing compound comprises nano-aluminum oxide powder with D50 < 100 nm and surface area ≥ 50 m 2 / g.

[0068] Preferably, the present invention provides a method according to the fourth aspect of the present invention, wherein the content of the fluoropolymer in the second mixture is between 0.1 wt% and 2.0 wt% relative to the total weight of the second mixture. Preferably, the content of the fluoropolymer in the second mixture is between 0.1 wt% and 0.5 wt%, more preferably, the content is equal to 0.2 wt%, 0.25 wt%, 0.3 wt%, 0.35 wt%, 0.4 wt%, or 0.45 wt%, or any value between them.

[0069] Preferably, the present invention provides a method according to the fourth aspect of the present invention, wherein the fluoropolymer is selected from PVDF homopolymers, PVDF copolymers, PVDF-HFP polymers (hexafluoropropylene), and PTFE polymers, or a combination of two or more of the above substances.

[0070] In a fifth aspect, the present invention provides the use of a positive electrode active material according to the first aspect of the present invention in a battery pack of any one of a portable computer, a tablet computer, a mobile phone, an electric vehicle, and an energy storage system.

[0071] Example

[0072] The following examples are intended to further illustrate the present invention and are not intended to limit the scope of the present invention.

[0073] 1. Description of the analysis method

[0074] 1.1. Inductively coupled plasma

[0075] The composition of the positive electrode active material powder was measured by an inductively coupled plasma (ICP) method using an Agilent 720 ICP-OES (Agilent Technologies, https: / / www.agilent.com / cs / library / brochures / 5990-6497EN%20720-725_ICP-OES_LR.pdf). 1 g of the powder sample was dissolved in 50 mL of high-purity hydrochloric acid (at least 37 wt% HCl relative to the total weight of the solution) in a conical 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 in the conical flask was poured into a first 250 mL volumetric flask. Then, the first volumetric flask was filled with deionized water up to the 250 mL mark and then subjected to a complete homogenization process (first dilution). An appropriate amount of the solution was taken from the first volumetric flask with a pipette and transferred to a second 250 mL volumetric flask for a second dilution. At this time, the internal standard element and 10% hydrochloric acid were filled into the second volumetric flask up to the 250 mL mark and then homogenized. Finally, the solution was used for ICP measurement.

[0076] 1.2. SEM (scanning electron microscope) analysis

[0077] The morphology of the positive electrode active material was analyzed by scanning electron microscopy (SEM) technology. Measurements were carried out at 25 °C in a high vacuum environment of 9.6x10 -5 Pa using a JEOL JSM7100F.

[0078] 1.3. Surface area analysis

[0079] The specific surface area of the powder was analyzed by the Brunauer-Emmett-Teller (BET) method using a Micromeritics Tristar 3000. Before measurement, the powder sample was heated at 300 °C for 1 hour under nitrogen (N2) gas to remove adsorbed substances. The dried powder was placed in a sample tube. Then the sample was degassed at 30 °C for 10 minutes. The instrument was used to conduct nitrogen adsorption tests at 77 K. The total specific surface area of the sample was derived by obtaining the nitrogen isothermal absorption / desorption curve, expressed in m 2 / g.

[0080] 1.4. Particle size distribution

[0081] After dispersing each powder sample in the powder sample in an aqueous medium, the particle size distribution (PSD) of the positive electrode active material powder was measured using a Malvern Mastersizer 3000 with a Hydro MV wet dispersion accessory (https: / / www.malvernpanalytical.com / en / products / product-range / mastersizer-range / mastersizer-3000#overview). To improve the dispersibility of the powder, sufficient ultrasonic radiation and stirring were applied, and an appropriate surfactant was introduced. D50 was defined as the particle size at 50% of the cumulative volume% distribution obtained from the measurement using a Malvern Mastersizer 3000 with Hydro MV.

[0082] 1.5. Polymer battery test

[0083] 1.5.1. Polymer battery preparation

[0084] 1.5.1.1. Solid polymer electrolyte (SPE) preparation

[0085] A solid polymer electrolyte (SPE) was prepared according to the following procedure:

[0086] Step 1) Using a mixer at 2000 revolutions per minute (rpm), mix polyethylene oxide (PEO, molecular weight 1,000,000, Alfa Aesar https: / / www.alfa.co.kr / AlfaAesarApp / faces / adf.task-flow?adf.tfId=Product DetailsTF&adf.tfDoc= / WEB-INF / ProductDetailsTF.xml&ProductId=043678&_afrLoop=1010520209597576&_afrWindowMode=0&_afrWindowId=null) with lithium bis(trifluoromethanesulfonyl)imide salt (LiTFSI, Soulbrain Co., Ltd.) in anhydrous 99.8 wt% acetonitrile (Aldrich https: / / www.sigmaaldrich.com / catalog / product / sial / 271004?lang=ko®ion=KR&gclid=EAIaIQobChMIwcrB0dDL6AIVBbeWCh0ieAXREAAYA SAAEgJCa_D_BwE) for 30 minutes. The molar ratio of ethylene oxide to lithium is 20.

[0087] Step 2) Pour the mixture obtained from Step 1) into a Teflon dish and dry it at 25 °C for 12 hours.

[0088] Step 3) Separate the dried SPE from the dish and punch the dried SPE to obtain an SPE disk with a thickness of 300 μm and a diameter of 19 mm.

[0089] 1.5.1.2. Cathode electrolyte electrode preparation

[0090] Prepare a cathode electrolyte electrode according to the following process:

[0091] Step 1) Prepare a polymer electrolyte mixture that contains a solution of polycaprolactone (PCL, with a molecular weight of 80,000, Sigma-Aldrich https: / / www.sigmaaldrich.com / catalog / product / aldrich / 440744) dissolved in anhydrous 99.7 wt% anisole (Sigma-Aldrich, https: / / www.sigmaaldrich.com / catalog / product / sial / 296295), and a lithium bis(trifluoromethanesulfonyl)imide salt (LiTFSI, Sigma-Aldrich, https: / / www.sigmaaldrich.com / catalog / product / aldrich / 544094) dissolved in acetonitrile. The weight ratio of PCL:LiTFSI in this mixture is 74:26.

[0092] Step 2) Mix the polymer electrolyte mixture prepared in Step 1, a positive electrode active material, and a 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) in an acetonitrile solution at a weight ratio of 21:75:4 to prepare a slurry mixture. Mix it for 45 minutes at 5000 rpm using a homogenizer.

[0093] Step 3) Cast the slurry mixture obtained from Step 2 onto one side of a 20-μm-thick aluminum foil, with a coater gap of 100 μm.

[0094] Step 4) Dry the slurry-cast foil at 30 °C for 12 hours and then punch it to obtain a cathode electrolyte electrode with a diameter of 14 mm.

[0095] 1.5.1.3. Polymer battery assembly

[0096] Assemble the coin-type polymer battery in an argon-filled glove box in the order from bottom to top: 2032 coin battery case, the cathode electrolyte electrode prepared in Section 1.5.1.2, the SPE prepared in Section 1.5.1.1, washer, Li anode, spacer, wave spring, and battery cover. Then, completely seal the coin battery to prevent electrolyte leakage.

[0097] 1.5.2. Test method

[0098] Use a Toscat-3100 computer-controlled constant current cycling station (obtained from Toyo, http: / / www.toyosystem.com / image / menu3 / toscat / TOSCAT-3100.pdf) to cycle each coin-type polymer battery at 80 °C. The coin battery test procedure is defined with a 10 current of 160 mA / g in the 4.4 - 3.0 V / Li metal window range according to the following schedule.

[0099] Step 1) Charge in constant current mode with a C-rate of 0.05, end condition of 4.4 V, and then rest for 10 minutes.

[0100] Step 2) Discharge in constant current mode with a C-rate of 0.05, end condition of 3.0 V, and then rest for 10 minutes.

[0101] Step 3) Charge in constant current mode with a C-rate of 0.05, end condition of 4.4 V.

[0102] Step 4) Switch to constant voltage mode and maintain 4.4 V for 60 hours.

[0103] Step 5) Discharge in constant current mode with a C-rate of 0.05, end condition of 3.0 V.

[0104] Q 总 is defined as the total leakage capacity at high voltage and high temperature in Step 4) according to the described test method. Q 总 A low Q value indicates high stability of the positive electrode active material powder during high-temperature operation.

[0105] 1.6. X-ray photoelectron spectroscopy (XPS)

[0106] 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., 1 nm to 10 nm) of the uppermost part (i.e., surface layer) of the sample. Therefore, all elements measured by XPS are included in the surface layer.

[0107] For the surface analysis of the positive electrode active material powder particles, XPS measurements were carried out using a Thermo K-a+ spectrometer (Thermo Scientific, https: / / www.thermofisher.com / order / catalog / product / IQLAADGAAFFACVMAHV).

[0108] Monochromatic Al Ka radiation (hu = 1486.6 eV) was used with a spot size of 400 μm and a measurement angle of 45°. Wide-scan measurements were performed at a pass energy of 200 eV to identify the elements present on the surface. The Cis peak with the maximum intensity (or centered) at a binding energy of 284.8 eV was used as the calibration peak position after data collection. Subsequently, at least 10 precise narrow-scans were performed for each identified element at 50 eV to determine the precise surface composition.

[0109] Curve fitting was performed using CasaXPS version 2.3.19PR1.0 (Casa Software, http: / / www.casaxps.com / ) with Shirley-type background processing and Scofield sensitivity factors. The fitting parameters conform to Table la. The line shape GL(30) is a Gaussian / Lorentzian product formula with 70% Gaussian line and 30% Lorentzian line. LA(α,β,m) is an asymmetric line shape, where a and p define the tail extension of the peak, and m defines the width.

[0110] Table 1a. XPS fitting parameters of Ni2p3, Mn2p3, Co2p3, Al2p and F1s 。

[0111]

[0112] For the Al peak in the fitting range of 64.1 ± 0.1 eV to 78.5 ± 0.1, constraint conditions were set for each defined peak according to Table lb. The Ni3p peak was not included in the quantification. Table lb. XPS fitting constraint conditions for Al2p peak fitting.

[0113]

[0114] The surface contents of Al and F are expressed as the atomic contents of Al and F in the particle surface layer divided by the total content of Ni, Mn, and / or Co in the surface layer. The calculation is as follows:

[0115]

[0116]

[0117] 2. Examples and comparative examples

[0118] Comparative example 1

[0119] The single-crystalline positive electrode active material powder labeled as CEX1 is obtained through a solid-state reaction between a lithium source and a nickel-based transition metal source, and the powder has the general formula Li 1.01 (Ni 0.63 Mn 0.22 Co 0.15 ) 0.99 O2. The process operates as follows:

[0120] Step 1) Preparation of the transition metal oxidized hydroxide precursor: In a large continuous stirred tank reactor (CSTR) with a mixture of nickel manganese cobalt sulfate, sodium hydroxide, and ammonia, a nickel-based transition metal oxidized hydroxide powder (TMH1) with a metal composition of Ni 0.63 Mn 0.22 Co 0.15 is prepared through a co-precipitation process.

[0121] Step 2) First mixing: Mix the TMH1 prepared in Step 1) with Li2CO3 in an industrial blender to obtain a first mixture with a lithium-to-metal ratio of 0.85.

[0122] Step 3) First calcination: Calcinate the first mixture obtained from Step 2) in a dry air atmosphere at 900 °C for 10 hours to obtain a first calcined cake. Crush the first calcined cake to obtain a first calcined powder.

[0123] Step 4) Second mixing: Mix the first calcined powder obtained from Step 3) with LiOH in an industrial blender to obtain a second mixture with a lithium-to-metal ratio of 1.05.

[0124] Step 5) Second calcination: Calcinate the second mixture from Step 4) in dry air at 930 °C for 10 hours, then perform a crushing (bead milling) and sieving process to obtain a second calcined powder.

[0125] Step 6) Third mixing: Mix the second calcined powder obtained from Step 5) with 2 mol% Co (e.g., obtained 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.

[0126] Step 7) Third calcination: Calcinate the third mixture obtained from Step 6) in dry air at 775 °C for 12 hours to produce a third calcined powder labeled as CEX1. The powder has a median particle size of 6.5 μm, as determined by laser diffraction measured with a Malvern Mastersizer 3000.

[0127] Example 1

[0128] Prepare the surface-modified single-crystal cathode active material EXI according to the following process:

[0129] Step 1) Mix 1 kg of CEX1 powder with 2 grams of alumina (Al2O3) nanopowder at 1000 rpm for 30 minutes.

[0130] Step 2) Bake the mixture obtained from Step 1) in a furnace under an oxidizing atmosphere flow at 750 °C for 10 hours.

[0131] Step 3) Mix 1 kg of the powder obtained from Step 2) with 2 grams of alumina (Al2O3) nanopowder and 3 grams of polyvinylidene fluoride (PVDF) powder at 1000 rpm for 30 minutes.

[0132] Step 4) Bake the mixture obtained from Step 3) in a furnace under an oxidizing atmosphere flow at 375 °C for 5 hours to produce a baked powder labeled EXI. This powder has a median particle size of 6.4 μm, as determined by laser diffraction measured with a Malvern Mastersizer 3000.

[0133] Comparative example 2

[0134] Obtain the single-crystal cathode active material labeled CEX2 through a solid-state reaction between a lithium source and a nickel-based transition metal source. The process operates as follows:

[0135] Step 1) Preparation of the transition metal oxidized hydroxide precursor: In a large continuous stirred tank reactor (CSTR) with mixed nickel manganese cobalt sulfate, sodium hydroxide, and ammonia, prepare nickel-based transition metal oxidized hydroxide powder (TMH2) with a metal composition of Ni 0.86 Mn 0.07 Co 0.07 by a coprecipitation process.

[0136] Step 2) Heating: Heat the TMH2 prepared in Step 1) in an oxidizing atmosphere at 400 °C for 7 hours to produce a heated powder.

[0137] Step 3) First mixing: Mix the heated powder prepared in Step 2) with LiOH in an industrial blender to obtain a first mixture with a lithium-to-metal ratio of 0.96.

[0138] Step 4) First baking: Bake the first mixture obtained from Step 3) in an oxidizing atmosphere at 890 °C for 11 hours, and then perform a wet bead milling and screening process to obtain a first baked powder.

[0139] Step 5) Second mixing: Mix the first calcined powder obtained from step 4) with LiOH in an industrial blender to obtain a second mixture with a lithium-to-metal ratio of 0.99.

[0140] Step 6) Second calcination: Calcinate the second mixture obtained from step 5) in oxidizing air at 760 °C for 10 hours, and then carry out a crushing and screening process to obtain a second calcined powder labeled CEX2. This powder has a median particle size of 4.5 μm, as determined by laser diffraction measured with a Malvern Mastersizer 3000.

[0141] Example 2

[0142] Prepare the surface-modified single-crystal positive electrode active material EX2 according to the same method as EXI, except that CEX2 is used instead of CEX1 in step 1) mixing. This powder has a median particle size of 4.5 μm, as determined by laser diffraction measured with a Malvern Mastersizer 3000.

[0143] Comparative example 3

[0144] Obtain the polycrystalline positive electrode active material labeled CEX3A through a solid-state reaction between a lithium source and a nickel-based transition metal source. The process operates as follows:

[0145] Step 1) Preparation of the transition metal oxide hydroxide precursor: In a large continuous stirred tank reactor (CSTR) with a mixture of nickel manganese cobalt sulfate, sodium hydroxide, and ammonia, prepare a nickel-based transition metal oxide hydroxide powder (TMH3) with a metal composition of Ni 0.625 Mn 0.175 Co 0.20 and an average particle size (D50) of 10.1 μm.

[0146] Step 2) First mixing: Mix the TMH3 prepared in step 1) with LiOH in an industrial blender to obtain a first mixture with a lithium-to-metal ratio of 1.03.

[0147] Step 3) First calcination: Calcinate the first mixture obtained from step 2) in a dry air atmosphere at 835 °C for 10 hours to obtain a first calcined cake. Crush the first calcined cake to obtain a first calcined powder.

[0148] Step 4) Second mixing: Mix the first calcined powder obtained from step 3) with LiOH in an industrial blender to obtain a second mixture with a lithium-to-metal ratio of 1.03.

[0149] Step 5) Second calcination: The second mixture obtained from Step 4) is calcined in dry air at 830 °C for 10 hours, followed by a grinding and sieving process to obtain a second calcined powder labeled CEX3A. This powder has a median particle size of 9.1 μm, as determined by laser diffraction measured with a Malvern Mastersizer 3000.

[0150] A surface-modified polycrystalline positive electrode active material CEX3B is prepared according to the same method as EXI, except that CEX3A is used instead of CEX1 in the mixing of Step 1).

[0151] Table 2. Summary of surface treatments of examples and comparative examples 。

[0152]

[0153] a As determined by ICP measurement, Me is the total atomic fraction of Ni + Mn + Co + Al.

[0154] b -: Not applicable.

[0155] c As determined by XPS measurement, Me is the total atomic fraction of Ni + Mn + Co.

[0156] Table 3. Summary of Q of Examples and Comparative Examples 总 ​

[0157]

[0158] Table 2 summarizes the compositions and surface treatments of the examples and comparative examples. Table 3 summarizes the Q 总 values.

[0159] First, it was observed that EXI has a significantly lower Q 总 compared to CEX1. The same observation was also obtained from EX2 and CEX3B when compared to CEX2 and CEX3A, respectively. This observation indicates that the surface-modified positive electrode active material powder according to the present invention has better electrochemical performance. A low Q 总 value indicates high stability of the positive electrode active material powder when applying a high voltage at high temperature.

[0160] Second, it was observed that the surface-modified positive electrode active material powder with a single-crystalline morphology is more effective compared to the polycrystalline morphology. Through surface treatment, the improvement in Q 总 from CEX1 to EXI (with a single-crystalline morphology) is 58.3%, while the improvement from CEX3A to CEX3B (with a polycrystalline morphology) is 23.7%. Therefore, in order to achieve the Q 总To achieve the target of less than 35 mAh / g, a synergistic effect between surface treatment and single-crystal morphology is required.

[0161] Again, the positive electrode active material powder with a Ni / Me content of 0.86 in EX2 was also surface-treated. The Q of EX2 总 was 32.2 mAh / g, which was much lower than the Q of CEX2 总 by a large margin.

[0162] Figure 2 The XPS spectra of the Al 2p peak and F Is peak of EX2 are shown. 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, J.F., Handbook of XPS, Perkin-Elmer, 1992).

[0163] The results are graphically depicted in Figure 3 which shows the synergistic effect between the composition of the surface layer and the morphology of the positive electrode active material on Q 总 where B and A on the x-axis represent before and after surface treatment, respectively.

Claims

1. A single-crystalline positive electrode active oxide material for a rechargeable battery pack, the single-crystalline positive electrode active oxide material comprising lithium, oxygen, nickel, and at least one metal selected from manganese and cobalt, It is characterized in that The single-crystalline positive electrode active oxide material further comprises: i) aluminum, and the single-crystalline positive electrode active oxide material has an atomic ratio of Al to the total amount of Ni, Mn, and Co of 1.0 to 7.0 as determined by XPS analysis, and ii) fluorine, and the single-crystalline positive electrode active oxide material has an atomic ratio of F to the total amount of Ni, Mn, and Co of 0.5 to 6.0 as determined by XPS analysis.

2. The single-crystalline positive electrode active oxide material according to claim 1, wherein the single-crystalline positive electrode active oxide material further comprises: i) aluminum, and the single-crystalline positive electrode active oxide material has an atomic ratio of Al to the total amount of Ni, Mn, and Co of 1.2 to 4.5 as determined by XPS analysis, and ii) fluorine, and the single-crystalline positive electrode active oxide material 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. The single-crystalline positive electrode active oxide material according to claim 1 or 2, wherein the single-crystalline positive electrode active oxide 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. The single-crystalline positive electrode active oxide material according to claim 1 or 2, wherein the single-crystalline positive electrode active oxide 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. The single-crystalline positive electrode active oxide material according to claim 1 or 2, wherein the particles have a nickel atomic content of 50% to 95% as determined by ICP relative to the total atomic content of Ni, Mn, and Co in the particles.

6. The single-crystalline positive electrode active oxide material according to claim 1 or 2, wherein the particles have an Al atomic content of 0.05% to 3.00% as determined by ICP relative to the total atomic content of Ni, Mn, and Co in the particles.

7. The single-crystalline positive electrode active oxide material according to claim 1 or 2, wherein the particles have a Co atomic content of 5.00% to 25.00% as determined by ICP relative to the total atomic content of Ni, Mn, and Co in the particles.

8. The single-crystalline positive electrode active oxide material according to claim 1 or 2, wherein the particles have an Mn atomic content of 0.00% to 70.00% as determined by ICP relative to the total atomic content of Ni, Mn, and Co in the particles.

9. The single-crystalline positive electrode active oxide material according to claim 1 or 2, wherein the particles have a median particle size d50 of 2 μm to 9 μm as determined by laser diffraction.

10. The single-crystalline positive electrode active oxide material according to claim 1 or 2, wherein the single-crystalline positive electrode active oxide material has a leakage capacity Q of at most 35 mAh / g 总 , whereby the leakage capacity Q 总 is determined by a button cell test procedure at 80 °C within a 4.4 - 3.0 V / Li metal window range using a 1C current definition of 160 mA / g.

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

12. A polymer battery pack, the polymer battery pack comprising a single-crystal positive electrode active oxide material according to any one of claims 1 to 10.

13. An electrochemical cell, the electrochemical cell comprising a single-crystal positive electrode active oxide material according to any one of claims 1 to 10.

14. A method for manufacturing a single-crystal positive electrode active oxide material according to any one of claims 1-10, the method comprising the steps of: - Mixing a single-crystal mixed metal oxide with a first Al-containing compound to obtain a first mixture, the single-crystal mixed metal oxide comprising lithium, nickel, and at least one metal selected from manganese and cobalt; - 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-treated 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 a single-crystal positive electrode active oxide material according to any one of claims 1 to 10 in a battery pack of any one of a portable computer, a mobile phone, an electric vehicle, and an energy storage system.

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