Method for coating cathode active materials and coated cathode active materials

Abstract

A method for coating a cathode active material for a lithium-ion battery, wherein the cathode active material comprises at least 50 mol-% nickel relative to a metal other than lithium, wherein the method comprises the following steps: (a) providing a cathode active material according to the general formula Li 1+x TM 1‑x The cathode active material of O2, wherein x is in the range of 0 to 0.2, TM is a combination of metals, wherein at least 95 mol-% of the combination is a transition metal, and at least 50 mol-% of TM is nickel, and TM contains at least one of cobalt and manganese, (b) the cathode active material is combined with Zr(OR) 1 The combination of 4 aqueous solutions, where R 1 (c) Adding LiOH·y H2O, where y is in the range of 0.5 to 3.0, (d) removing the solvent, and (e) heat-treating the residue at a temperature in the range of 300°C to 450°C.

Description

[0001] This invention relates to a method for coating a cathode active material for a lithium-ion battery, wherein the cathode active material comprises at least 50 mol-% nickel relative to metals other than lithium, and wherein the method comprises the following steps:

[0002] (a) Provided according to the general formula Li 1+x TM 1-x The cathode active material of O2, wherein x is in the range of 0 to 0.2, TM is a combination of metals, wherein at least 95 mol-% of the combination is a transition metal, and at least 50 mol-% of TM is nickel, and TM contains at least one of cobalt and manganese.

[0003] (b) The cathode active material is reacted with Zr(OR) 1 The combination of 4 aqueous solutions, where R 1 The molecules are the same or different and selected from straight-chain or branched C2-C4-alkyl groups, and the water content is determined by Karl-Fischer titration to be 650 ppm or less.

[0004] (c) Add LiOH·yH2O, where y is in the range of 0.5 to 3.0.

[0005] (d) Remove one or more solvents.

[0006] (e) Heat-treat the residue at a temperature in the range of 300°C to 450°C.

[0007] Lithium-ion secondary batteries are modern devices used for energy storage. They have been and are being considered for numerous applications, ranging from small devices such as mobile phones and laptops to automotive batteries and batteries for other electric vehicles. Various battery components, such as the electrolyte, electrode materials, and separator, play a decisive role in battery performance. Particular attention has been paid to cathode materials. Several materials have been proposed, such as lithium iron phosphate, lithium cobalt oxide, and lithium nickel cobalt manganese oxide. Despite extensive research, the solutions found to date still have room for improvement.

[0008] Currently, there is some interest in so-called Ni-rich cathode active materials, such as cathode active materials containing 75 mol% or more of Ni relative to the total TM content.

[0009] One problem with lithium-ion batteries—especially Ni-rich cathode active materials—is attributed to undesirable reactions on the surface of the cathode active material. Such reactions can be the decomposition of the electrolyte or solvent, or both. Therefore, attempts have been made to protect the surface without hindering lithium exchange during charge and discharge. An example is the attempt to coat the cathode active material with, for example, alumina or calcium oxide, see, for example, US 8,993,051.

[0010] Other theories attribute the undesirable reaction to free LiOH or Li₂CO₃ on the surface. Attempts have been made to remove this free LiOH or Li₂CO₃ by washing the cathode active material with water, see, for example, JP 4,789,066 B, JP 5,139,024 B, and US 2015 / 0372300. However, in some cases, the properties of the resulting cathode active material have not been improved.

[0011] Several other coating methods have been explored, such as precipitating the coating material via sol-gel precipitation followed by drying. However, it has been found that agglomerates may form after such drying, remaining as sieving residues.

[0012] The object of this invention is to provide a method for manufacturing Ni-rich cathode active materials with excellent electrochemical properties and low loss after sieving. Another object is to provide Ni-rich cathode active materials with excellent electrochemical properties, particularly low resistivity growth during cycling and high-temperature storage.

[0013] Accordingly, the method initially defined has been discovered, and is referred to hereinafter as "the method of the present invention". The method of the present invention includes the following steps:

[0014] (a) Provided according to the general formula Li 1+x TM 1-x The cathode active material of O2, wherein x is in the range of 0 to 0.2, TM is a combination of metals, wherein at least 95 mol-% of the combination is a transition metal, and at least 50 mol-% of TM is nickel, and TM contains at least one of cobalt and manganese.

[0015] (b) The cathode active material is reacted with Zr(OR) 1 The combination of 4 aqueous solutions, where R 1 Identical or different and selected from straight-chain or branched C2-C4-alkyl groups

[0016] (c) Add LiOH·yH2O, where y is in the range of 0.5 to 3.0.

[0017] (d) Remove one or more solvents.

[0018] (e) Heat-treat the residue at a temperature in the range of 300°C to 450°C.

[0019] The method of the present invention comprises at least five steps: (a), (b), (c), (d), and (e), which in the context of the present invention are also referred to as steps (a), (b), (c), (d), and (e), respectively. Steps (a) through (e) are performed sequentially.

[0020] In step (a), the method of the present invention begins with a cathode active material based on a TM-based lithium oxide, wherein TM is a combination of metals, of which at least 95 mol-% is a transition metal, and at least 50 mol-% and preferably at least 60 mol-% of TM is nickel. Furthermore, TM contains at least one of Co and Mn, preferably TM contains Co and Al or Co and Mn and optionally Al. The material is also referred to hereinafter as a starting material. Preferably, the cathode active material is a TM-based lithium oxide. The TM-based lithium oxide may contain impurities derived from its manufacture, such as residual lithium hydroxide, residual lithium carbonate, and / or phosphate, each of which is less than 1% by weight, preferably less than 0.5% by weight.

[0021] In one embodiment of the present invention, the cathode active material provided in step (a) is based on the general formula Li 1+x TM 1-x The material of O2, wherein TM is a combination of metals, of which at least 95 mol-% are transition metals and at least 50 mol-% of TM is nickel, and TM contains at least one transition metal selected from Co and Mn, and optionally at least one element selected from Al and Mg, and x is in the range of 0 to 0.2. Preferably, at least 75 mol-% of TM is Ni.

[0022] In one embodiment of the invention, the starting material has an average particle size (D50) in the range of 1 to 10 µm, preferably 2 to 7 µm. The average particle size can be determined, for example, by light scattering, laser diffraction, or electron-acoustic spectroscopy. The particles typically consist of agglomerates of primary particles, and the above particle size refers to the secondary particle size.

[0023] In one embodiment, the cathode active material provided in step (a) is in the form of a monolithic material. In this embodiment, primary particles cannot be distinguished. Such monolithic materials may have irregular shapes, such as in the form of potatoes or droplets. In a preferred embodiment of the invention, the cathode active material provided in step (a) is in the form of secondary particles, which are agglomerates from primary particles. They are sometimes also referred to as polycrystalline. The secondary particles are preferably spherical or quasi-spherical in nature.

[0024] In one embodiment of the invention, the secondary particles of the cathode active material provided in step (a) are agglomerates of primary particles that are substantially radially oriented.

[0025] "Basically radial orientation" does not require perfect radial orientation, but rather includes a deviation from perfect radial orientation of up to 5 degrees in SEM analysis. The radial orientation of primary particles can be determined, for example, by performing SEM (scanning electron microscopy) on cross-sections of at least 5 secondary particles.

[0026] In one embodiment of the invention, the starting material has a particle size of 0.1 to 2.0 m. 2 The specific surface area (BET) in the range of / g, also referred to below as "BET surface area". The BET surface area can be determined according to DIN ISO 9277:2010 by nitrogen adsorption after degassing the sample at 200°C for 30 minutes or longer.

[0027] In one embodiment of the invention, the particulate material provided in step (a) has a moisture content in the range of 20 to 2,000 ppm, preferably 50 to 1,200 ppm, as determined by Karl Fischer titration.

[0028] In one embodiment of the invention, TM corresponds to 50 to 99.9 mol-% nickel, 0 to 50 mol-% cobalt and 0 to 50 mol-% manganese, wherein at least one of cobalt and manganese is present.

[0029] In one embodiment of the present invention, the variable TM corresponds to general formula (I).

[0030] (Ni a Co b Mn c ) 1-d M 1 d (I)

[0031] Where a + b + c = 1 and

[0032] a is in the range of 0.6 to 0.99, preferably 0.75 to 0.95, and more preferably 0.85 to 0.95.

[0033] b is 0 or in the range of 0.01 to 0.2, preferably 0.025 to 0.2, more preferably 0.025 to 0.1.

[0034] c is in the range of 0 to 0.2, preferably 0.025 to 0.2, and more preferably 0.05 to 0.1.

[0035] d is in the range of 0 to 0.1, preferably 0 to 0.04.

[0036] M 1 It is at least one of Al, Mg, Ti, Nb, Mo, W and Zr, preferably at least one of Al, Ti, Zr and W.

[0037] In one embodiment of the present invention, variable c is 0, M 1 It is Al, and d is in the range of 0.01 to 0.05.

[0038] In one embodiment of the invention, TM corresponds to general formula (I), and x is in the range of 0 to 0.2, preferably 0 to 0.1, and even more preferably 0.01 to 0.05.

[0039] In one embodiment of the present invention, TM is selected from Ni. 0.6 Co 0.2 Mn 0.2 Ni 0.7 Co 0.2 Mn 0.1 Ni 0.8 Co 0.1 Mn 0.1 Ni 0.83 Co 0.12 Mn 0.05 Ni 0.89 Co 0.055 Al 0.055 Ni 0.91 Co 0.045 Al 0.045 and Ni 0.85 Co 0.1 Mn 0.05 .

[0040] The cathode active material provided in step (a) is generally free of conductive carbon, which means that the conductive carbon content of the starting material is less than 1% by weight, preferably 0.001% to 1.0% by weight, relative to the starting material.

[0041] Some elements are ubiquitous. In the context of this invention, trace amounts of ubiquitous metals such as sodium, calcium, iron, or zinc, which are impurities, will not be considered in the description of this invention. Trace amounts in this context will mean an amount of 0.02 mol-% or less relative to the total metal content of the starting material.

[0042] Trace amounts of sulfate derived from the synthesis of particulate cathode active materials will also be disregarded.

[0043] In step (b), the starting material is mixed with Zr(OR) 1 The combination of 4 aqueous solutions, where R 1The same or different and selected from straight-chain or branched C2-C4-alkyl groups, such as ethyl, n-propyl, n-butyl, isopropyl, isobutyl, or sec-butyl. Specific examples are Zr(OC2H5)4, Zr(On-C3H7)4, Zr(O-iso-C3H7)4, Zr(On-C4H9)4, Zr(O-iso-C4H9)4, or Zr(O-tert-C4H9)4.

[0044] In the context of step (b), the term anhydrous means a solvent having a water content of 650 ppm or less, preferably 75 ppm or less, as determined by Karl Fischer titration. Ethanol having a water content in the range of 350 to 650 ppm is also acceptable. Unless otherwise stated, the term ppm means ppm by mass.

[0045] Examples of suitable solvents are C2-C4 alkanols, such as ethanol, isopropanol, n-butanol, sec-butanol, THF (tetrahydrofuran), N-methylpyrrolidone (“NMP”), and dimethyl sulfoxide (“DMSO”). The corresponding alkanol R is preferred. 1 -OH, especially ethanol, n-propanol, and n-butanol. Mixtures of at least two of the above solvents are also feasible, such as ethanol and R... 1 A mixture of -OH groups.

[0046] In one embodiment of the present invention, Zr(OR) 1 )4 The concentration in the non-aqueous solution is in the range of 0.8 to 2.5 mol / L.

[0047] In one embodiment of the present invention, Zr(OR) 1 The weight ratio of the non-aqueous solution of step (4) to the cathode active material provided in step (a) is in the range of 1:1 to 1:10, preferably 1:3 to 1:6.

[0048] In one embodiment of the invention, step (b) is carried out in a mixer, a rotary kiln, or a dryer such as a vacuum dryer, flash dryer, rotary dryer, high-shear dryer, annular dryer, film dryer, screw conveyor dryer, or paddle dryer. Preferably, step (b) is carried out in a paddle dryer, such as a vacuum paddle dryer or a conical paddle dryer.

[0049] In one embodiment of the invention, the time between step (b) and step (c) is in the range of 0 to 60 minutes, preferably 2 to 30 minutes.

[0050] In one embodiment of the invention, step (b) is performed at a temperature in the range of 15°C to 40°C.

[0051] Obtain a mud or mud-like phase.

[0052] In step (c), LiOH·yH2O (where y is in the range of 0.5 to 3.0, preferably 1.0 to 2.5) is added to the mud-like phase or slurry produced in step (b). In the formula LiOH·yH2O, y represents the average value. This LiOH·yH2O can be added in bulk or solution form, with bulk being preferred. Alcohol R is used as the solvent. 1 -OH is the most suitable.

[0053] The molar amount of LiOH·yH2O can be in the range of 1:1 to 4:1, preferably 1.5:1 to 2.5:1, relative to the Zr added in step (b).

[0054] After or during step (b) or (c), one or more mixing operations, such as stirring or shaking, are initiated. During one or more such mixing operations, the temperature may be ambient temperature or higher, for example, up to the boiling point of the non-aqueous solvent.

[0055] In step (d), one or more solvents are preferably removed by evaporation. Step (d) can be carried out under reduced pressure (“in a vacuum”) or at ambient pressure. In embodiments where step (d) is carried out at ambient pressure, it can be carried out in an atmosphere of air, nitrogen, or oxygen-enriched air.

[0056] In one embodiment of the invention, step (d) is performed at a temperature ranging from 65°C to 165°C. The temperature is determined at a set point for the corresponding container.

[0057] In one embodiment of the invention, step (d) has a duration ranging from 5 minutes to 12 hours, preferably from 60 minutes to 5 hours.

[0058] In one embodiment of the invention, step (d) is performed in a rotary kiln, mixer, or dryer as disclosed above. In laboratory-scale experiments (e.g., with 10 g or less of sample), step (d) may also be performed in a drying oven or rotary evaporator.

[0059] The residue is obtained from step (d). The residue may have the appearance of a free-flowing powder or form a layer and requires deagglomeration. Depending on the nature of one or more solvents used in steps (b) and (c), the residue may contain some residual solvent, for example, up to 5% by weight, if applicable.

[0060] In step (e), the residue from step (d) is heat-treated at a temperature ranging from 300°C to 450°C. This treatment can be carried out in a rotary kiln, roller kiln, fluidized bed, or moving bed. In laboratory-scale experiments (e.g., with 10 g or less of sample), step (e) can also be carried out in a muffle furnace.

[0061] In one embodiment of the invention, the temperature is gradually increased to a desired temperature of 300°C to 450°C. For example, the residue from step (d) is heated to a temperature of 250°C to 300°C and then held constant for 10 minutes to 4 hours, and then raised to 325°C to 450°C.

[0062] In one embodiment of the invention, the heating rate in step (e) is in the range of 0.1 to 10°C / min.

[0063] In one embodiment of the invention, step (e) has a duration ranging from thirty minutes to 24 hours, preferably from 45 to 120 minutes. When measuring the duration of step (e), the time required to reach the desired temperature is ignored.

[0064] In one embodiment of the invention, step (e) is performed under oxidizing conditions (e.g., oxygen-enriched air or a pure oxygen atmosphere).

[0065] In one embodiment of the invention, steps (b) to (d), and especially step (e), are carried out in an atmosphere with a reduced CO2 content, for example, a CO2 content in the range of 0.01 to 500 ppm by weight, preferably 0.1 to 50 ppm by weight. The CO2 content can be determined by, for example, an optical method using infrared light. Even more preferably, step (d) is carried out in an atmosphere with a CO2 content below the detection limit, for example, using an infrared light-based optical method.

[0066] In one embodiment of the invention, the heat treatment step (e) is carried out in a roller hearth kiln, a pusher kiln, or a rotary kiln, or a combination of at least two of the foregoing. The advantage of a rotary kiln is that the material produced therein exhibits excellent homogeneity. In both roller hearth kilns and pusher kilns, different reaction conditions for different steps can be readily established. Box furnaces, tube furnaces, and split-tube furnaces are also feasible in laboratory-scale experiments.

[0067] By carrying out the method of the present invention, cathode active materials exhibiting excellent electrochemical performance, especially high-temperature storage stability, can be obtained.

[0068] Another aspect of the invention is a coated cathode active material, also referred to hereinafter as the cathode active material of the invention. It is advantageously synthesized according to the method of the invention.

[0069] The cathode active material of the present invention comprises

[0070] (1) According to the general formula Li 1+x TM 1-x The core material of O2, wherein TM is a combination of metals, wherein at least 95 mol-% of the combination is a transition metal and at least 50 mol-% of TM is nickel, and TM contains at least one of cobalt and manganese, and the core (1) is a polycrystalline material.

[0071] (2) A layer on the outer surface, which contains a zirconium lithide compound and lithium carbonate.

[0072] The core (1) has an average particle size (D50) in the range of 1 to 10 µm, and the layer (2) is uniform and has a thickness in the range of 2 to 10 nm.

[0073] The thickness of the layer can be determined by transmission electron microscopy (“TEM”). The uniformity of the layer can be determined by X-ray photoelectron spectroscopy (“XPS”).

[0074] TM has been defined in more detail above.

[0075] In one embodiment of the invention, the cathode active material of the invention has an average particle size (D50) in the range of 1 to 10 µm, preferably 2 to 7 µm, more preferably 3 to 5 µm. The average particle size (50) can be determined, for example, by light scattering or laser diffraction or electron-acoustic spectroscopy. The particles are typically composed of agglomerates of primary particles, and the above particle size refers to the secondary particle size.

[0076] In one embodiment of the invention, the cathode active material of the invention has a molecular weight distribution of 0.1 to 2.0 μm as determined according to DIN-ISO 9277:2003-05. 2 Surface area (BET) within the range of / g.

[0077] Another aspect of the invention relates to electrodes comprising at least one cathode active material according to the invention. These are particularly suitable for lithium-ion batteries. Lithium-ion batteries comprising at least one electrode according to the invention exhibit good discharge behavior. Electrodes comprising at least one cathode active material according to the invention are hereinafter also referred to as cathodes of the invention or cathodes according to the invention.

[0078] Specifically, the cathode of the present invention contains

[0079] (A) At least one cathode active material of the present invention.

[0080] (B) Carbon in a conductive form,

[0081] (C) Adhesive material, also known as adhesive or binder (C), and preferably,

[0082] (D) Current collector.

[0083] In a preferred embodiment, the cathode of the present invention contains

[0084] (A) 80% to 98% by weight of the cathode active material of the present invention.

[0085] (B) 1% to 17% carbon by weight,

[0086] (C) 1% to 15% by weight of adhesive material,

[0087] The percentage is relative to the sum of (A), (B), and (C).

[0088] The cathode according to the invention may contain additional components. These may include current collectors, such as, but not limited to, aluminum foil. They may further contain conductive carbon and a binder.

[0089] The cathode according to the present invention contains conductive modified carbon, also simply referred to as carbon (B). Carbon (B) may be selected from soot, activated carbon, carbon nanotubes, graphene and graphite, and combinations of at least two of the foregoing.

[0090] A suitable adhesive (C) is preferably selected from organic (co)polymers. Suitable (co)polymers, i.e., homopolymers or copolymers, can be selected, for example, from (co)polymers obtainable by anionic, catalytic, or free radical (co)polymerization, particularly from polyethylene, polyacrylonitrile, polybutadiene, polystyrene, and copolymers of at least two comonomers selected from ethylene, propylene, styrene, (meth)acrylonitrile, and 1,3-butadiene. Polypropylene is also suitable. Additionally, polyisoprene and polyacrylates are suitable. Polyacrylonitrile is particularly preferred.

[0091] In the context of this invention, polyacrylonitrile should be understood not only to polyacrylonitrile homopolymers, but also to copolymers of acrylonitrile with 1,3-butadiene or styrene. Polyacrylonitrile homopolymers are preferred.

[0092] In the context of this invention, polyethylene should be understood to mean not only homopolymer polyethylene, but also copolymers of ethylene comprising at least 50 mol% of copolyethylene and up to 50 mol% of at least one additional comonomer, such as α-olefins such as propylene, butene (1-butene), 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-pentene, and isobutylene, vinyl aromatic compounds such as styrene, and (meth)acrylic acid, vinyl acetate, vinyl propionate, C1-C of (meth)acrylic acid. 10 alkyl esters, especially methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-butyl acrylate, 2-ethylhexyl acrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, as well as maleic acid, maleic anhydride and itaconic anhydride. Polyethylene can be HDPE or LDPE.

[0093] In the context of this invention, polypropylene should be understood not only to homopolymer polypropylene but also to copolymers of propylene comprising at least 50 mol% copolypropylene and up to 50 mol% of at least one additional comonomer, such as ethylene and α-olefins such as butene, 1-hexene, 1-octene, 1-decene, 1-dodecene, and 1-pentene. The polypropylene is preferably isotactic or substantially isotactic polypropylene.

[0094] In the context of this invention, polystyrene should be understood not only to homopolymers of styrene, but also to C1-C polymers of acrylonitrile, 1,3-butadiene, (meth)acrylic acid, and (meth)acrylic acid. 10 α-alkyl esters, copolymers of divinylbenzene, especially 1,3-divinylbenzene, 1,2-diphenylethylene and α-methylstyrene.

[0095] Another preferred adhesive (C) is polybutadiene.

[0096] Other suitable adhesives (C) are selected from polyethylene oxide (PEO), cellulose, carboxymethyl cellulose, polyimide and polyvinyl alcohol.

[0097] In one embodiment of the invention, the adhesive (C) is selected from those having an average molecular weight M in the range of 50,000 to 1,000,000 g / mol, preferably up to 500,000 g / mol. w Those (co)polymers.

[0098] The adhesive (C) can be a crosslinked or non-crosslinked (co)polymer.

[0099] In a particularly preferred embodiment of the invention, the adhesive (C) is selected from halogenated (co)polymers, especially fluorinated (co)polymers. Halogenated or fluorinated (co)polymers should be understood to mean those (co)polymers comprising at least one (co)polymerized (co)monomer, each molecule of which has at least one halogen atom or at least one fluorine atom, more preferably each molecule has at least two halogen atoms or at least two fluorine atoms. Examples are polyvinyl chloride, polyvinylidene chloride, polytetrafluoroethylene, polyvinylidene fluoride (PVdF), tetrafluoroethylene-hexafluoropropylene copolymer, vinylidene fluoride-hexafluoropropylene copolymer (PVdF-HFP), vinylidene fluoride-tetrafluoroethylene copolymer, perfluoroalkyl vinyl ether copolymer, ethylene-tetrafluoroethylene copolymer, vinylidene fluoride-chlorotrifluoroethylene copolymer, and ethylene-chlorofluoroethylene copolymer.

[0100] Suitable adhesives (C) are especially polyvinyl alcohol and halogenated (co)polymers, such as polyvinyl chloride or polyvinylidene chloride, especially fluorinated (co)polymers such as polyvinylidene fluoride and especially polyvinylidene fluoride and polytetrafluoroethylene.

[0101] The cathode of the present invention may contain one or more adhesives at 1% to 15% by weight relative to the cathode active material. In other embodiments, the cathode of the present invention may contain one or more adhesives at 0.1% to less than 1% by weight.

[0102] Another aspect of the invention is a battery comprising at least one cathode containing the cathode active material of the invention, carbon, and a binder, at least one anode, and at least one electrolyte.

[0103] The embodiments of the cathode of the present invention have been described in detail above.

[0104] The anode may contain at least one anodic active material, such as carbon (graphite), TiO2, lithium titanium oxide, silicon, or tin. The anode may also contain a current collector, such as a metal foil like copper foil.

[0105] The electrolyte may contain at least one non-aqueous solvent, at least one electrolyte salt, and optionally additives.

[0106] The non-aqueous solvent of the electrolyte can be liquid or solid at room temperature and is preferably selected from polymers, cyclic or acyclic ethers, cyclic and acyclic acetals, and cyclic or acyclic organic carbonates.

[0107] Examples of suitable polymers include, in particular, polyalkylene glycols, preferably poly-C1-C4-alkylene glycols, and especially polyethylene glycol. Polyethylene glycol may comprise up to 20 mol% of one or more C1-C4-alkylene glycols. The polyalkylene glycol is preferably a polyalkylene glycol having two methyl or ethyl terminals.

[0108] Suitable polyalkylene glycols, and especially suitable polyethylene glycols, have a molecular weight M. w It can be at least 400 g / mol.

[0109] Suitable polyalkylene glycols, and especially suitable polyethylene glycols, have a molecular weight M. w It can be up to 5,000,000 g / mol, preferably up to 2,000,000 g / mol.

[0110] Suitable examples of acyclic ethers are, for example, diisopropyl ether, di-n-butyl ether, 1,2-dimethoxyethane, and 1,2-diethoxyethane, with 1,2-dimethoxyethane being preferred.

[0111] Suitable examples of cyclic ethers are tetrahydrofuran and 1,4-dioxane.

[0112] Suitable examples of acyclic acetals are, for example, dimethoxymethane, diethoxymethane, 1,1-dimethoxyethane, and 1,1-diethoxyethane.

[0113] Suitable examples of cyclic acetals are 1,3-dioxanes and especially 1,3-dioxolane.

[0114] Suitable examples of acyclic organic carbonates are dimethyl carbonate, ethyl methyl carbonate, and diethyl carbonate.

[0115] Suitable examples of cyclic organic carbonates are compounds based on general formulas (II) and (III).

[0116]

[0117] Where R 1 R 2 and R 3 They may be the same or different and selected from hydrogen and C1-C4-alkyl, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, and tert-butyl, wherein R 2 and R 3 Preferably, not all of them are tert-butyl.

[0118] In a particularly preferred embodiment, R 1 It is methyl and R 2 and R 3 Each is hydrogen, or R 1R 2 and R 3 Each is hydrogen.

[0119] Another preferred cyclic organic carbonate is vinylene carbonate, formula (IV).

[0120]

[0121] The one or more solvents are preferably used in an anhydrous state, i.e., wherein the water content is in the range of 1 ppm to 0.1% by weight, which can be determined, for example, by Karl Fischer titration.

[0122] The electrolyte (C) further comprises at least one electrolyte salt. Suitable electrolyte salts are, in particular, lithium salts. Examples of suitable lithium salts are LiPF6, LiBF4, LiClO4, LiAsF6, LiCF3SO3, and LiC(C). n F 2n+1 SO2)3, lithium iminoides such as LiN(C) n F 2n+1 SO2)2—where n is an integer in the range of 1 to 20, LiN(SO2F)2, Li2SiF6, LiSbF6, LiAlCl4, and those with the general formula (C n F 2n+1 SO2) t Salts of YLi — where m is defined as follows:

[0123] When Y is selected from oxygen and sulfur, t = 1.

[0124] When Y is selected from nitrogen and phosphorus, t = 2, and

[0125] When Y is selected from carbon and silicon, t = 3.

[0126] The preferred electrolyte salts are selected from LiC(CF3SO2)3, LiN(CF3SO2)2, LiPF6, LiBF4, and LiClO4, with LiPF6 and LiN(CF3SO2)2 being particularly preferred.

[0127] In embodiments of the invention, the battery according to the invention comprises one or more separators by means of which the electrodes are mechanically separated. Suitable separators are polymer membranes, particularly porous polymer membranes, which are non-reactive to metallic lithium. Materials particularly suitable for use as separators are polyolefins, especially film-forming porous polyethylene and film-forming porous polypropylene.

[0128] Membranes made of polyolefins, particularly polyethylene or polypropylene, can have a porosity in the range of 35% to 45%. Suitable pore sizes are, for example, in the range of 30 to 500 nm.

[0129] In another embodiment of the invention, the diaphragm may be selected from a PET nonwoven material filled with inorganic particles. Such a diaphragm may have a porosity in the range of 40% to 55%. Suitable pore sizes are, for example, in the range of 80 to 750 nm.

[0130] The battery according to the invention further includes a casing, which can have any shape, such as a cubic or cylindrical disc or cylindrical can. In one variation, a metal foil configured as a pouch is used as the casing.

[0131] The battery according to the invention exhibits, for example, good discharge behavior at low temperatures (0°C or lower, such as down to -10°C or even lower), very good cycle behavior, and good high-temperature storage behavior.

[0132] A battery according to the invention may comprise two or more electrochemical cell units combined with each other, which may be connected in series or in parallel, for example. Series connection is preferred. In a battery according to the invention, at least one of the electrochemical cell units includes at least one cathode according to the invention. Preferably, in an electrochemical cell unit according to the invention, most of the electrochemical cell units include a cathode according to the invention. Even more preferably, in a battery according to the invention, all electrochemical cell units include a cathode according to the invention.

[0133] The present invention further provides the use of the battery according to the invention in devices, particularly in mobile devices. Examples of mobile devices are vehicles of transportation, such as cars, bicycles, airplanes, or watercraft such as boats or ships. Other examples of mobile devices are those that are manually moved, such as computers (especially laptops), telephones, or electric hand tools, such as drilling rigs, battery-powered screwdrivers, or battery-powered staplers, especially in the construction industry.

[0134] Another aspect of the invention relates to the use of the cathode active material of the invention in or for manufacturing lithium-ion batteries, preferably in or for manufacturing all-solid-state lithium-ion batteries. In particular, the cathode active material of the invention can be incorporated into a cathode (A) for use in an all-solid-state lithium-ion battery. A cathode comprising at least one cathode active material according to the invention is hereinafter also referred to as a cathode of the invention or a cathode according to the invention.

[0135] The electrochemical battery cell of the present invention, as an all-solid-state battery, further includes

[0136] (C) Solid electrolytes containing lithium, sulfur and phosphorus, also referred to below as electrolytes (C) or solid electrolytes (C).

[0137] In this context, the term "solid" refers to the state of matter at ambient temperature.

[0138] In one embodiment of the invention, the solid electrolyte (C) has a lithium-ion conductivity of ≥ 0.1 mS / cm, preferably in the range of 0.1 to 30 mS / cm, at 25°C, which can be measured, for example, by impedance spectroscopy.

[0139] In one embodiment of the invention, the solid electrolyte (C) comprises Li3PS4, more preferably orthorhombic β-Li3PS4.

[0140] In one embodiment of the invention, the solid electrolyte (C) is selected from the group consisting of: Li2S-P2S5, Li2S-P2S5-LiI, Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2-P2S5-LiI, Li2S-P2S5-Z m S n —Where m and n are positive numbers and Z is a member of the group consisting of germanium, gallium, and zinc, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li y PO z —where y and z are positive numbers, Li7P3S 11 Li3PS4, Li 11 S2PS 12 Li7P2S8I and Li 7-r-2s PS 6-r- s X r —Where X is chlorine, bromine, or iodine, and the variables are defined as follows:

[0141] 0.8 ≤ r ≤ 1.7

[0142] 0 ≤ s ≤ (-0.25 r) + 0.5.

[0143] A particularly preferred example of a solid electrolyte (C) is Li6PS5Cl, where r = 1.0 and s = 0.

[0144] In one embodiment of the invention, the electrolyte (C) is doped with at least one of Si, Sb, and Sn. Si is preferably provided in elemental form. Sb and Sn are preferably provided in sulfide form.

[0145] In one embodiment of the invention, the electrochemical cell cell of the invention comprises a solid electrolyte (C) comprising 1% to 50% by weight, preferably 3% to 30% by weight, relative to the total mass of the cathode (A).

[0146] The present invention is further illustrated by working examples.

[0147] General instructions:

[0148] Rpm: revolutions per minute

[0149] Anhydrous ethanol is produced using standard laboratory drying methods. It contains 53.9 ppm water (Karl Fischer titration).

[0150] Anhydrous 1-propanol is prepared using standard laboratory drying methods. It contains 57.4 ppm of water (Karl Fischer titration). Unless otherwise stated, ppm refers to ppm by weight.

[0151] TEM (Transmission Electron Microscopy):

[0152] For transmission electron microscopy (TEM), particles of the corresponding cathode active material were embedded in Epofix epoxy resin (Struers). Thin sections were prepared at ambient temperature using Ultra-Micotomy (Leica).

[0153] The surface of the particles was imaged using bright-field high-resolution TEM (Thermo-Fisher Themis Z3.1 operated at 300 kV) to identify secondary phases segregated at the surface. The chemical composition of the material in the cross-section was analyzed using a combination of high-angle annular dark-field scanning TEM (HAADF-STEM) and energy-dispersive X-ray spectroscopy (EDS) (Thermo-Fisher SuperX EDS analysis system). Micrographs and elemental maps were analyzed using Thermo-Fisher Velox 3 software.

[0154] XPS analysis was performed using a Phi Versa Probe 5000 spectrometer (Ulvac PHI, Michigan (MI)) with monochromatic Al Kα radiation (49.9 W). The XPS system was calibrated according to ISO 15472.2001. The BE (binding energy) for Au 4f7 / 2 was 84.00 eV and the BE for Cu2p3 / 2 was 932.62 eV.

[0155] All samples were placed in an argon-filled glove box and transferred under argon atmosphere to a load lock via the supplier's transfer container to prevent any contact with air and moisture.

[0156] All samples were mounted insulated from the ground and neutralized with a built-in charge neutralizer during measurement. Measurements were performed at three non-overlapping sample locations using a 200 µm × 200 µm spot size, a flux of 117 eV, and an energy step of 0.5 eV. High-resolution analysis was then performed over the same analytical region using a flux of 23.5 eV and an energy step of 0.1 eV.

[0157] The total residence time for each energy step is 3000 ms for Ni 2p, 600 ms for O 1s, 600 ms for C 1s, 1800 ms for Zr 3d+ P2s, 3000 ms for Li 1s, and 600 ms for the measured spectrum.

[0158] The spectra have been charged to the position of the hydrocarbon peak in C1s, which is 284.8 eV for all samples.

[0159] All spectra were analyzed using standard XPS analysis software (i.e., CasaXPS version 2.3.26rev1.1) with background subtraction, where the average background value was 5 (average width) in the measured spectra and 20 in the detailed spectra. Quantification was performed using the relative sensitivity factor and transmission function provided by the instrument manufacturer.

[0160] The table below shows the integration region and background types used for quantitative spectral measurements:

[0161] Table 1: Signal Overview

[0162]

[0163] Elemental quantification was performed from the measured spectrum, and the ratio of Zr to Ni was then calculated by dividing the two values.

[0164] Based on the fitting of the C1s-detail spectrum, the lithium carbonate concentration was calculated based on the amount of carbonate-carbon:

[0165] The C 1s signal was fitted using five spectral lines.

[0166]

[0167] The resulting ratio (in percentage) is then renormalized to the atomic concentration of total carbon, as quantified from the measured spectrum, and the total amount of Li₂CO₃ is then calculated by multiplying this value by a factor of 6 based on the nominal stoichiometry of Li₂CO₃.

[0168] c CO3（总） = (c C（测量） c CO3（细节）) / 100

[0169] c Li2C O3 = c CO3（总） 6

[0170] I. Synthesis of cathode active materials

[0171] I.1 Synthesis of basic cathode active materials, step (a.1)

[0172] The basic cathode active material is synthesized stoichiometrically from a hydroxide precursor by reacting a dried precursor with LiOH. xH2O and 0.1 mol-% WO3 (relative to the sum of Ni+Mn+Co) were mixed at a molar ratio of Li:(Ni+Co+Mn+W) of 1.04:1. The resulting mixture was then packed into a crucible and heated at 3°C / min to 760°C, and held at this temperature for 6 h. The calcined material thus obtained was cooled to ambient temperature and sieved using a 32 µm sieve. B-CAM.1 (D90: 7.3 µm) with a D50 of 4.0 µm was obtained.

[0173] I.2 Coating Steps

[0174] I.2.1 Synthesis of CAM.2 of the present invention

[0175] Step (b.2):

[0176] A 4.8 g solution of zirconium butoxide (IV) (80 wt.% in 1-butanol) was diluted with 44 ml of anhydrous ethanol and then added to B-CAM.1 so that the molar ratio of Zr to TM was 0.5%. The weight ratio of the diluted solution to B-CAM.1 was 1:5. A mud-like mixture was obtained.

[0177] Step (c.2): Add solid LiOH·2,46H2O to the muddy mixture from step (b.2). The molar ratio of Zr:Li is 1:2.

[0178] Steps (d.2) and (e.2): The resulting mixture was dried under vacuum at 70°C for 15 hours, and then calcined at 375°C for one hour in a pure oxygen atmosphere. The resulting CAM.2 was sieved through a 32 µm sieve with a sieve loss of <0.8%.

[0179] I.2.2 Synthesis of CAM.3 of the present invention

[0180] Step (b.3)

[0181] A 4.8 g solution of zirconium butoxide (IV) (80 wt.% in 1-butanol) was diluted with 44 ml of anhydrous ethanol and then added to B-CAM.1 so that the molar ratio of Zr to TM was 0.5%. The weight ratio of the diluted solution to B-CAM.1 was 1:5. A mud-like mixture was obtained.

[0182] Step (c.3): Add LiOH·2,46H2O powder to the mud-like mixture from step (b.3). The molar ratio of Zr:Li is 1:2.

[0183] Steps (d.3) and (e.3): The resulting mixture was dried under vacuum at 70°C for 15 hours, and then calcined at 375°C for one hour in a synthesis air atmosphere. The resulting CAM.3 was sieved through a 32 µm sieve with a sieve loss of 0.8%.

[0184] I.2.3: Synthesis of CAM.4 of the present invention

[0185] Step (b.4): According to Table 1, dilute the zirconium propoxide (IV) solution (70 wt.% in 1-propanol) with 1-propanol and then add it to B-CAM.1. The weight ratio of diluted solution to B-CAM.1 is 1:5. A mud-like mixture is obtained.

[0186] Step (c.4): Then, LiOH··2.46H2O is added to the muddy mixture from step (b.4). The molar ratio of Zr to Li is 1:2.

[0187] Steps (d.4) and (e.4): The resulting mixture was dried under vacuum at 80°C for 15 hours, and then calcined at 375°C for one hour in a synthesis air atmosphere. The resulting CAM.4 was sieved through a 32 µm sieve with a sieve loss of < 0.45%. TEM-EDX images are shown below. Figure 1 As shown.

[0188] I.2.4: Sol-gel coating, comparison

[0189] According to Table 2, a zirconium butoxide (IV) solution (80 wt.% in 1-butanol) and lithium ethoxide (95%) were dissolved in anhydrous ethanol, with a Zr:Li molar ratio of 1:2. For complete dissolution, the solution was stirred at 45°C for 17 hours. B-CAM.1 was added to the solution and stirred at 45°C. The solution:B-CAM.1 weight ratio was 5:1. After stirring for 30 minutes, water (0.27 wt% relative to B-CAM.1) was added for gelation. After stirring at 45°C for 1.5 hours, the resulting mixture was dried under vacuum at 50°C in a rotary evaporator and subsequently calcined at 375°C for one hour in a synthetic air atmosphere. The resulting C-CAM.5 was sieved through a 32 µm sieve with a sieve loss of 5.5%. TEM EDX images are shown below. Figure 2 As shown.

[0190] I.2.5: Synthesis of C-CAM.6, in comparison

[0191] Step (b.4): According to Table 1, dilute the zirconium propoxide (IV) solution (70 wt.% in 1-propanol) with 1-propanol and then add it to B-CAM.1. The weight ratio of diluted solution to B-CAM.1 is 1:5. A mud-like mixture is obtained.

[0192] Step C-(c.4): Then, dry LiOH powder is added to the mud-like mixture from step (b.4). The molar ratio of Zr to Li is 1:2.

[0193] Steps C-(d.4) and C-(e.4): The resulting mixture was dried under vacuum at 80°C for 15 hours and then calcined at 375°C for one hour in a synthesis air atmosphere. The resulting C-CAM.6 was sieved through a 32 µm sieve with a sieve loss of 15%.

[0194] Table 2: Analytical properties of the cathode active materials of the present invention and C-CAM.5 and C-CAM.6

[0195]

[0196] nd: Undetermined

[0197] XPS measurement refers to the external secondary particle surface.

[0198] II. Testing the fabrication and electrochemical performance of battery cells

[0199] II.1 Testing the Manufacturing of Battery Cells

[0200] In a zirconia ball mill, 690 mg of the corresponding cathode active material, 10 mg of amorphous carbon (C65), and 300 mg of β-Li6PS5Cl, along with 10 zirconia balls (10 mm in diameter), were mixed at 140 rpm for 30 min to produce a cathode composite material. The electrochemical cell unit used for electrochemical testing employed a mixture containing Li4Ti5O... 12 An anode composite material of conductive carbon (C65) and Li6PS5Cl (30:10:60 wt.-%), a separator, and a cathode as described above were used. SSB cell units (10 mm in diameter) were tested using a custom setup. In the assembly procedure, β-Li6PS5Cl (100 mg) was compressed at 62 MPa to produce a solid electrolyte sheet. The anode composite material (65 mg, approximately 4.0 mA h cm⁻²) was then pressed onto the solid electrolyte sheet, and finally, the cathode composite material (10 to 12 mg, 1.7 to 2.0 mA h cm⁻²) was pressed at 437 MPa. -2 The electrolyte was pressed onto the other side of the solid electrolyte sheet. A pressure of 81 MPa was maintained during electrochemical testing. Electrochemical tests were conducted between 1.4 and 2.8 V (relative to Li₄Ti₅O₂). 12 The charging process was carried out within the range of 1 C = 190 mA / g CAM (equivalent to 3-4.4 V relative to Li), with the state of charge being Li7Ti5O. 12 Initially, the test began with a 2-hour open-circuit voltage (OCV) cycle. Then, three cycles of galvanostatic intermittent titration (GITT) were performed at C / 3 and 25°C. Following this, the battery cells were charged in constant current / constant voltage (CCCV) mode (CV phase lasting 1 hour at 2.8 V), and then subjected to a long-term 168-hour OCV cycle at 60°C. This was followed by a GITT discharge step. Finally, three more GITT cycles were performed at 25°C. The tests were conducted using the MACCOR battery testing system.

[0201] The area resistivity (ASR) was measured at 25°C and calculated using the current interruption method outlined below:

[0202] ASR = S (V1 - V2) / I,

[0203] Where V1 is the voltage at the end of the current interruption, V2 is the initial voltage value after the charging process continues in constant current mode, I is the charging current used during constant current mode, and S is the electrode surface area, expressed in square centimeters (cm²). 2The ASR growth (%) before and after the high-temperature (60°C) OCV cycle is measured in units of 0.5. The ASR growth (%) before and after the OCV cycle is determined as follows: ASR growth = ASR (after OCV) - ASR (before OCV). ASR growth is used to evaluate the material.

[0204] Table 3: Electrochemical tests and particle size distribution of the cathode active material and comparative material (similar to WO 2023 / 121838) of this invention

[0205] .

Claims

1. A method for coating a cathode active material for a lithium-ion battery, wherein the cathode active material comprises at least 50 mol-% nickel relative to a metal other than lithium, wherein the method comprises the following steps: (a) Provided according to the general formula Li 1+x TM 1-x The cathode active material of O2, wherein x is in the range of 0 to 0.2, TM is a combination of metals, wherein at least 95 mol-% of the combination is a transition metal, and at least 50 mol-% of TM is nickel, and TM contains at least one of cobalt and manganese. (b) The cathode active material is reacted with Zr(OR) 1 The combination of 4 aqueous solutions, where R 1 Identical or different and selected from straight-chain or branched C2-C4-alkyl groups (c) Add LiOH·yH2O, where y is in the range of 0.5 to 3.

0. (d) Remove one or more solvents. (e) Heat-treat the residue at a temperature in the range of 300°C to 450°C.

2. The method according to claim 1, wherein, Step (d) is carried out by evaporation.

3. The method according to claim 1 or 2, wherein, The solvent in step (b) is selected from C2-C4-alkanols.

4. The method according to any one of the preceding claims, wherein, TM is a combination of metals according to formula (I). (Ni a Co b Mr c ) 1-d M d (I) in a is in the range of 0.6 to 0.

95. b is in the range of 0.025 to 0.

2. c is in the range of 0 to 0.2, and d is in the range of 0.02 to 0.

1. M is selected from Mg, Al, Ca, Si, Ti, Zr, Mo, W, Nb, and Ta. a + b + c = 1.

5. The method according to any one of the preceding claims, wherein, TM contains 0.5 to 2 mol% W.

6. The method according to any one of the preceding claims, wherein, The molar ratio of TM to Zr ranges from 120:1 to 500:

1.

7. The method according to any one of the preceding claims, wherein, The water content of the anhydrous solvent used in step (b) was determined by Karl Fischer titration to be in the range of 1 to 500 ppm.

8. The method according to any one of the preceding claims, wherein, The molar ratio of Li added in step (d) to Zr added in step (b) is in the range of 1:1 to 3:

1.

9. The method according to any one of the preceding claims, wherein, The cathode active material provided in step (a) has an average particle size (D50) in the range of 2 to 7 µm.

10. The method according to any one of the preceding claims, wherein, The cathode active material provided in step (a) is in the form of secondary particles, which are composed of agglomerates from primary particles.

11. A coated cathode active material comprising (1) According to the general formula Li 1+x TM 1-x The core material of O2, wherein x is in the range of 0 to 0.2, TM is a combination of metals, wherein at least 95 mol-% of the combination is a transition metal and at least 50 mol-% of TM is nickel, and TM contains at least one of cobalt and manganese, and the core (1) is a polycrystalline material. (2) A layer on the outer surface, which contains a zirconium lithide compound and lithium carbonate. The core (1) has an average particle size (D50) in the range of 1 to 10 µm, and The layer (2) is uniform and has a thickness in the range of 2 to 10 nm.

12. The coated cathode active material according to claim 11, wherein, TM is a combination of metals according to formula (I). (Ni a Co b Mr c ) 1-d M d (I) in a is in the range of 0.6 to 0.

95. b is in the range of 0.025 to 0.

2. c is in the range of 0 to 0.2, and d is in the range of 0.02 to 0.

1. M is selected from Mg, Al, Ca, Si, Ti, Zr, Mo, W, Nb, and Ta. a + b + c = 1.

13. Use of the coated cathode active material according to claim 11 or 12 in the manufacture of an all-solid-state battery.

14. A cathode comprising (A) At least one cathode active material according to claim 11 or 12, (B) Carbon in a conductive form, (C) Adhesive materials, and, (D) Current collector.

15. An electrochemical battery cell, comprising: (1) A cathode comprising the coated cathode active material according to claim 11 or 12, (2) Anode, and (3) An electrolyte containing a sulfide corresponding to formula (II). The 7-r-2s PS 6-r-s X r (II), in X is chlorine, bromine, or iodine. ≤ r ≤ 1.7 and s 0 ≤ s ≤ (-0.25 r) + 0.5, or Li3PS4.

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