Method for producing doped cathode active material

Abstract

Provided is a cathode active material having improved stability, for example, lower capacity fading and improved cycle stability. SOLUTION: A particulate cathode active material represented by the general formula Li 1+x TM 1-x O 2-y F y , wherein the particulate cathode active material has an average particle diameter (D50) in a range of 3 to 16 µm, TM contains Ni and at least one of Mn and Co, and TM is represented by the following formula (Ni a Co b Mn c ) 1-d Md, wherein a is in a range of 0.6 to 0.99, b is 0 or in a range of 0.01 to 0.2, c is in a range of 0 to 0.2, d is in a range of 0 to 0.1, M is at least one selected from the group consisting of Al, Mg, Ti, Mo, Nb, Ta, W and Zr, and a + b + c = 1, x is in a range of 0 to 0.2, y is in a range of 0.0002 to 0.03, and F is uniformly dispersed in the cathode active material.

Description

[Technical Field]

[0001] The present invention relates to a method for producing a fluoride-doped cathode active material, wherein the method comprises the following steps: (a) A step of providing particulate oxide or (oxy)hydroxide of TM, wherein TM comprises nickel and at least one metal selected from cobalt and manganese, and the particulate oxide or (oxy)hydroxide has an average particle size (D50) in the range of 3 to 16 μm. (b) A step of providing a lithium source containing 0.01 to 2.5 mass% of fluoride, wherein the fluoride is uniformly dispersed within the lithium source. (c) A step of mixing the oxide or (oxy)hydroxide of TM with the fluoride-containing lithium source, optionally an additional lithium source containing less fluoride, and optionally one or more dopants based on at least one metal other than lithium. (d) A step of heat-treating the mixture obtained from step (c) Includes. [Background technology]

[0002] Lithium-ion rechargeable batteries are state-of-the-art devices for energy storage. Many applications have been considered, from small devices such as mobile phones and laptop computers to car batteries and other e-mobility batteries. Various battery components, such as electrolytes, electrode materials, and separators, play crucial roles in battery performance. Cathode materials, in particular, have received attention. Several materials have been proposed, such as lithium iron phosphate, lithium cobalt oxide, and lithium nickel cobalt manganese oxide. While extensive research has been conducted, the solutions found so far still have room for improvement.

[0003] Generally, cathode active materials are produced using a two-step process. In the first step, a sparingly soluble compound of a transition metal (one or more) is produced by precipitating it from a solution, such as a carbonate or hydroxide. The sparingly soluble salt is often also called a precursor. In the second step, the precursor is mixed with a lithium compound, such as Li2CO3, LiOH, or Li2O, and calcined at a high temperature, such as 600-1100°C. In special recipes, dopants, such as alumina, titania, zirconia, or oxides or (oxy)hydroxides of transition metals such as Nb, Ta, W, and Mo, may be added.

[0004] Currently, there is particular interest in so-called nickel-rich electrode active materials, such as those containing at least 50 mol% or 75 mol% or more of Ni relative to the total metal content (where metal refers to metals other than lithium). Several technical questions remain unresolved. Volume energy density, capacity fade, and cycle stability are still areas of research and development. Some of the problems stem from the volume change of the cathode active material during charging and discharging. It has been proposed to suppress volume change by incorporating fluoride; see, for example, US 5,773,168. The disclosed method involves mixing a small amount of lithium fluoride with another lithium source, such as lithium carbonate, and then calcining it. However, the quality of such materials is often quite non-uniform. US 2015 / 0064563 proposes incorporating fluoride by heat-treating the cathode active material with a fluorinated polymer, such as polyvinylidene difluoride.

[0005] US 2013 / 0209840 discloses a fluoride coating process. Fluoride coating affects only the outer surface of each cathode active material. In N. Zhang et al., J. Electrochem. Soc. 2020, 167, 080815, the authors report on experiments in fluoride doping by mixing precursors with LiOH·H2O and LiF, followed by a two-step calcination process. [Prior art documents] [Patent Literature]

[0006] [Patent Document 1] US 5,773,168 [Patent Document 2] US 2015 / 0064563 [Patent Document 3] US 2013 / 0209840 [Non-Patent Literature]

[0007] [Non-Patent Document 1] N. Zhang et al., J. Electrochem. Soc. 2020, 167, 080815 [Summary of the Invention] [Problem to be Solved by the Invention]

[0008] Accordingly, an object of the present invention is to provide a cathode active material having improved stability, such as lower capacity fading and improved cycle stability. Furthermore, an object of the present invention is to provide a method for producing a cathode active material having improved stability, such as lower capacity fading and improved cycle stability. [Means for Solving the Problem]

[0009] Accordingly, a method as defined in the preamble, hereinafter also referred to as "the method of the present invention" or "method according to (the present) invention", has been found. The method of the present invention comprises a series of a plurality of steps as defined in the preamble, which are also hereinafter referred to as step (a), step (b), step (c), and so on. Hereinafter, the method of the present invention will be described in more detail. [Mode for Carrying Out the Invention]

[0010] Step (a) comprises providing particulate oxide or (oxy)hydroxide of TM, wherein TM comprises nickel and at least one metal selected from cobalt and manganese, and the particulate oxide or (oxy)hydroxide has an average particle size (D50) in the range of 3 to 16 μm, preferably 5 to 12 μm. The particulate oxide or (oxy)hydroxide of TM is also called a precursor.

[0011] In one embodiment of the present invention, the precursor comprises at least one of Mg, Al, and Y, or at least one transition metal selected from Ti, Zr, Nb, Ta, Fe, Mo, and W. In another embodiment, the precursor does not contain any metals other than nickel, cobalt, and manganese or nickel, cobalt, and aluminum.

[0012] In one embodiment of the present invention, TM is of general formula (I) (NiaCobMnc)1-dMd (I) (In the formula, a is in the range of 0.6 to 0.99, preferably 0.6 to 0.95, more preferably 0.8 to 0.93) b is in the range of 0 or 0.01 to 0.2, preferably 0.05 to 0.1. c is in the range of 0 to 0.2, preferably 0.03 to 0.15. d is in the range of 0 to 0.1, preferably 0.01 to 0.05. M is at least one of Al, Mg, Ti, Mo, Nb, Ta, W, and Zr. b+c>0, (a + b + c = 1) It corresponds to.

[0013] Preferably, the precursor is obtained by coprecipitation of nickel, cobalt, and manganese as hydroxides from an aqueous solution containing nickel and cobalt and / or manganese nitrates, acetates, or preferably sulfates in stoichiometric ratios corresponding to TM. The coprecipitation can be achieved by adding alkali metal hydroxides, such as potassium hydroxide or sodium hydroxide, in a continuous, semi-continuous, or batch process. The coprecipitation is then removed, for example, by filtration, and then by removing water.

[0014] The precursor is particulate. In one embodiment of the present invention, the average particle size (D50) of the precursor is in the range of 3 to 16 μm, preferably 5 to 12 μm, and more preferably 7 to 10 μm. In the context of the present invention, the average particle size (D50) refers to the average value of the volume-based particle size, which can be determined, for example, by light scattering. In one embodiment, the precursor has a unimodal particle size distribution. In other embodiments, the particle distribution of the precursor may be bimodal, for example, having one maximum value in the range of 1 to 5 μm and a further maximum value in the range of 7 to 16 μm.

[0015] The particle shape of the secondary particles of the precursor is spherical. Spherical particles include not only particles that are perfectly spherical, but also particles in which the difference between the maximum diameter and minimum diameter is 10% or less for at least 90% (number mean) of a representative sample.

[0016] In one embodiment of the present invention, the precursor is composed of secondary particles which are aggregates of primary particles. Preferably, the precursor is composed of spherical secondary particles which are aggregates of primary particles. More preferably, the precursor is composed of spherical secondary particles which are aggregates of spherical primary particles or platelets.

[0017] In one embodiment of the present invention, the precursor has a particle size distribution span in the range of 0.5 to 0.9, which is defined as [(D90)-(D10)] divided by (D50), all determined by LASER analysis. In another embodiment of the present invention, the precursor may have a particle size distribution span in the range of 1.1 to 1.8.

[0018] In one embodiment of the present invention, the specific surface area (BET) of the precursor is determined by nitrogen adsorption, for example, according to DIN-ISO 9277:2003-05, and is 2 to 10 m 2 / g, or over 10 to 100m 2 It is within the range of / g.

[0019] Some metals are ubiquitous, such as sodium, calcium, or zinc, and while trace amounts of these are virtually everywhere, such trace amounts are not considered in the specification of this invention. In this context, trace amounts of metal mean amounts of 0.05 mol% or less relative to the total metal content TM.

[0020] The precursor may contain sulfates, for example, 0.1 to 0.5% by mass of sulfates as determined by ion chromatography. The precursor may also contain carbonates, for example, 0.1 to 2% by mass of carbonates, where each percentage is relative to the total mass of the precursor.

[0021] In step (b), a lithium source is provided, wherein the source contains 0.01 to 2.5% by mass of fluoride uniformly dispersed within the lithium source. 0.05 to 0.5% by mass is preferred. The percentages are for each lithium source. The fluoride is preferably lithium fluoride, but may have counterions other than lithium and counterions derived from impurities. Preferably, the majority of the fluoride is lithium fluoride. More preferably, the fluoride is lithium fluoride.

[0022] The lithium source is selected from lithium carbonate, lithium oxide, Li2O, and lithium hydroxide, LiOH, and includes (but is not limited to) lithium hydroxide hydrate, such as LiOH·H2O. Lithium oxide, Li2O, and lithium hydroxide, LiOH are preferred.

[0023] In the lithium source, the fluoride is preferably uniformly dispersed as lithium fluoride. The term "uniformly dispersed" means that no separate crystals or even accumulations of fluoride or LiF are detected, for example, by X-ray diffraction, particle size distribution, optical microscopy, and SEM / EDX (scanning electron microscopy / energy-dispersive X-ray spectroscopy). Particle size distribution, X-ray diffraction, and SEM / EDX are preferred.

[0024] Preferably, the fluoride-containing lithium source is produced by a recycling process that recovers lithium carbonate or lithium hydroxide from a solution of lithium salt containing fluoride derived from an electrolyte such as LiPF6 or a decomposed fluorine-containing polymer binder, for example, by recycling used batteries.

[0025] In one embodiment of the present invention, the recycling process comprises the following steps: (i) A process of producing a black powder, also called a black mass or activated mass, from used lithium-ion batteries by mechanically destroying the used lithium-ion batteries and then heat-treating them. (ii) A step of treating the black powder with at least one of Ca(OH)2 or Mg(OH)2 in the presence of water or a polar solvent other than water at a temperature of at least 70°C, preferably 70 to 120°C. (iii) Preferably by filtration, the solid is separated from the liquid, and optionally the solid residue is subsequently washed with a polar solvent such as water to obtain a solution of lithium hydroxide containing fluoride, and (iv) After optionally purifying the lithium hydroxide solution, water is removed from the lithium hydroxide solution in one or more steps, for example by evaporation, to obtain solid LiOH. Includes.

[0026] In other embodiments, after steps (i) to (iii), step (v), (v) A step of adding CO2 or any water-soluble carbonate, such as Na2CO3, to precipitate Li2CO3. (vi) A solid-liquid separation method, for example by filtration, which separates the solid from the liquid, and optionally subsequently washes the solid residue with a polar solvent such as water, thereby obtaining solid lithium carbonate containing fluoride. And so it continues.

[0027] Lithium hydroxide produced according to the above recycling process generally contains 0.01 to 1.3% by mass, preferably 0.05 to 0.5% by mass, of fluoride relative to the monohydrate of LiOH. Depending on the drying conditions, anhydrous LiOH may be obtained instead of the monohydrate. In this case, the amount of the characteristic impurities associated with the monohydrate is approximately 1.75 times higher than that of 100% anhydrous LiOH (corresponding to the value obtained by dividing the molar mass of the monohydrate by the molar mass of the anhydrous LiOH).

[0028] Lithium carbonate produced according to the above recycling process generally contains 0.01 to 1.5% by mass, preferably 0.05 to 0.5% by mass, of fluoride.

[0029] Step (c) comprises mixing an oxide or (oxy)hydroxide of TM with the fluoride-containing lithium source, optionally an additional lithium source containing less fluoride, and optionally one or more dopants based on at least one metal other than lithium. By performing step (c), a mixture is obtained. The expression “the fluoride-containing lithium source” refers to the one provided in step (b). The expression “containing less fluoride” refers to a comparison with the lithium source provided in step (b).

[0030] The total amount of the precursor and lithium source mixed corresponds to the desired stoichiometry of the intended cathode active material. Typically, a stoichiometric amount or a slight excess of lithium relative to other metals is selected.

[0031] Step (c) may include mixing with an additional lithium source containing less fluoride than the lithium source provided in step (b), for example, 1 to 15 ppm, or below the detection level.

[0032] The dopants are selected from oxides, hydroxides, and oxyhydroxides of Mg, Ti, Zr, W, Nb, Ta, and especially Al. Examples of dopants include MgO, Mg(OH)2, TiO2 (selected from rutile and anatase, with anatase being preferred), basic titania such as TiO(OH)2, and Li4Ti5O 12 These include ZrO2, Zr(OH)4, Li2ZrO3, Nb2O3, Ta2O5, Li2WO4, WO3, MoO3, Li2MoO4, Al(OH)3, Al2O3, Al2O3·aq, and AlOOH. Al compounds, such as Al(OH)3, α-Al2O3, γ-Al2O3, Al2O3·aq, and AlOOH, and TiO2 and Zr(OH)4 are preferred. A more preferred dopant is Al2O3 selected from α-Al2O3 and γ-Al2O3, with γ-Al2O3 being the most preferred.

[0033] In a preferred embodiment, the dopant(s)

[0034] Examples of suitable apparatus for carrying out process (c) include high-shear mixers, tumbler mixers, plow shear mixers, and free-fall mixers.

[0035] In one embodiment of the present invention, step (c) is carried out at a temperature in the range of room temperature to 200°C, preferably 20 to 50°C.

[0036] In one embodiment of the present invention, step (c) has a duration of 10 minutes to 2 hours. Depending on whether additional mixing is performed in step (d), complete mixing must be achieved in step (c).

[0037] The mixing of the precursor, the lithium source from step (b), and any further lithium sources and / or dopants (one or more) can all be carried out in one or more sub-steps, for example, by first mixing the fluoride-containing lithium source with the dopant and then adding the mixture to the precursor; or by first mixing the precursor and the fluoride-containing lithium source and then adding the dopant and further lithium sources; or by first mixing the dopant and the precursor and then adding the fluoride-containing lithium source and further lithium sources. It is preferable to first mix the precursor and both lithium sources and then add the dopant.

[0038] In one embodiment of the present invention, step (c) comprises two sub-steps, (c1) A lithium source containing fluoride, a lithium source not containing fluoride, and a sub-step of optionally mixing the dopants (one or more), (c2) A sub-step in which the mixture obtained from sub-step (c1) is mixed with the oxide or (oxy)hydroxide of TM. Includes.

[0039] In one embodiment of the present invention, the mass ratio of the fluoride-containing lithium source provided in step (b) to the fluoride-free lithium source is in the range of 1:1 to 1:20.

[0040] In step (c), it is possible to add an organic solvent, such as glycerol or glycol, or water, but it is preferable to carry out step (c) in a dry state, that is, without adding water or an organic solvent.

[0041] A mixture is obtained.

[0042] Step (d) includes heat-treating the mixture at a temperature in the range of 600 to 950°C, preferably 650 to 925°C.

[0043] In one embodiment of the present invention, the mixture from step (c) is heated to 650 to 1000°C at a heating rate of 0.1 to 10°C / min.

[0044] In one embodiment of the present invention, the temperature is raised before reaching a desired temperature of 650°C to 1000°C, preferably 750°C to 900°C. For example, first the mixture from step (c) is heated to 350°C to 550°C, then held at a constant temperature for 10 minutes to 4 hours, and then raised to 650°C to 1000°C.

[0045] In embodiments in which at least one solvent is used in step (c), the solvent(s) are removed, either as part of or separately in step (d), before step (d) is initiated, for example, by filtration, evaporation, or distillation of the solvent(s). Evaporation and distillation are preferred.

[0046] In one embodiment of the present invention, step (d) is carried out in a roller hearth kiln, a pusher kiln, or a rotary kiln, or a combination of at least two of the above. The rotary kiln has the advantage of providing very good homogenization of the material produced therein. In roller hearth kilns and pusher kilns, different reaction conditions for different steps can be set very easily. In laboratory-scale experiments, box furnaces, tubular furnaces, and segmented tubular furnaces can also be used.

[0047] In one embodiment of the present invention, step (d) is carried out in an oxygen-containing atmosphere, such as a nitrogen-air mixture, a noble gas-oxygen mixture, air, oxygen, or oxygen-enriched air. In a preferred embodiment, the atmosphere in step (d) is selected from air, oxygen, and oxygen-enriched air. The oxygen-enriched air may be, for example, a mixture of air and oxygen in a volume ratio of 50:50. Other options include a mixture of air and oxygen in a volume ratio of 1:2, a mixture of air and oxygen in a volume ratio of 1:3, a mixture of air and oxygen in a volume ratio of 2:1, and a mixture of air and oxygen in a volume ratio of 3:1.

[0048] In one embodiment of the present invention, the stoichiometry of lithium in step (c) is in the range of 90 to 95 mol% of the total non-lithium metals from TM and the dopant(s), and, where applicable, step (d) is followed by another mixing step with a lithium source and another heat treatment step.

[0049] By performing the method of the present invention, a cathode active material exhibiting excellent stability, such as low capacity fade and high cycle stability, can be produced.

[0050] Another aspect of the present invention is a cathode active material, also referred to below as the cathode active material of the present invention. The cathode active material of the present invention has the general formula Li 1+x TM 1-x O 2-y F y It is expressed as having an average particle size (D50) in the range of 3 to 16 μm, preferably 5 to 12 μm, and more preferably 7 to 10 μm. In the cathode active material of the present invention, TM comprises Ni and at least one of Mn and Co, x is in the range of 0 to 0.2, y is in the range of 0.0002 to 0.03, and F is uniformly dispersed in the cathode active material.

[0051] The fluoride (F) is uniformly dispersed in the cathode active material of the present invention. In other words, F does not accumulate on the outer surface of secondary particles, but is present inside the secondary particles. Some fluoride may accumulate at the grain boundaries of primary particles, but preferably there is no accumulation. Furthermore, there are almost no secondary particles that do not contain fluoride.

[0052] The cathode active material of the present invention is in the form of particles. In one embodiment of the present invention, the average particle diameter (D50) of the cathode active material of the present invention is in the range of 3 to 16 µm, preferably 5 to 12 µm, more preferably 7 to 10 µm. The average particle diameter (D50) in the context of the present invention refers to a volume-based average particle diameter, which can be determined, for example, by light scattering. In one embodiment, the precursor has a unimodal particle size distribution. In another embodiment, the particle distribution of the precursor may be bimodal having, for example, one maximum in the range of 1 to 5 µm and a further maximum in the range of 7 to 16 µm.

[0053] The particle shape of the secondary particles of the cathode active material of the present invention is spherical particles, which are particles having a spherical shape. Spherical particles include not only particles that are exactly spherical, but also particles in which the difference between the maximum diameter and the minimum diameter of at least 90% (number average) of a representative sample is 10% or less.

[0054] In one embodiment of the present invention, the cathode active material of the present invention is composed of secondary particles which are aggregates of primary particles. Preferably, the precursor is composed of spherical secondary particles which are aggregates of primary particles. Even more preferably, the precursor is composed of spherical secondary particles which are aggregates of spherical primary particles or platelets.

[0055] In one embodiment of the present invention, the cathode active material of the present invention has a particle size distribution span in the range of 0.5 to 0.9, which span is defined as [(D90)-(D10)] divided by (D50), all determined by laser analysis. In another embodiment of the present invention, the precursor may have a particle size distribution span in the range of 1.1 to 1.8.

[0056] In one embodiment of the present invention, the specific surface area (BET) of the cathode active material of the present invention is determined by nitrogen adsorption in accordance with, for example, DIN-ISO 9277:2003-05, and is 0.1 to 1.5 m 2 / g, preferably 0.2 to 1.0 m 2 / g.

[0057] In one embodiment of the present invention, TM in the cathode active material of the present invention is general formula (I) (Ni a Co b Mn c ) 1-d M d (I) (In the formula, a is in the range of 0.6 to 0.99, preferably 0.6 to 0.95, more preferably 0.8 to 0.93) b is in the range of 0 or 0.01 to 0.2, preferably 0.05 to 0.1. c is in the range of 0 to 0.2, preferably 0.03 to 0.15. d is in the range of 0 to 0.1, preferably 0.01 to 0.05. M is at least one of Al, Mg, Ti, Mo, Nb, Ta, W, and Zr. (a + b + c = 1) It is a combination of metals.

[0058] A further aspect of the present invention is an electrode comprising at least one particulate cathode active material according to the present invention. These are particularly useful in lithium-ion batteries. A lithium-ion battery comprising at least one electrode according to the present invention exhibits good cycle behavior / stability. An electrode comprising at least one particulate cathode active material according to the present invention is hereinafter also referred to as the cathode of the present invention or the cathode according to the present invention.

[0059] Specifically, the cathode of the present invention is (A) at least one particulate cathode active material of the present invention, (B) Conductive carbon, (C) Binder material also called binder or binder(C), and preferably, (D) Current collector It contains.

[0060] In a preferred embodiment, the cathode of the present invention is based on the sum of (A), (B), and (C), (A) 80-98% by mass of the particulate cathode active material of the present invention, (B) 1-17% by mass of carbon, (C) Binders of 1-15% by mass It contains.

[0061] The cathode according to the present invention may include further components, which may include current collectors, such as aluminum foil (but not limited to this). They may further include conductive carbon and a binder.

[0062] The cathode according to the present invention contains conductively modified carbon, also abbreviated as carbon(B). Carbon(B) can be selected from soot, activated carbon, carbon nanotubes, graphene, graphite, and a combination of at least two of the above.

[0063] A suitable binder (C) is preferably selected from organic (co)polymers. Suitable (co)polymers, i.e., homopolymers or copolymers, can be selected from (co)polymers that can be obtained by anionic (co)polymerization, catalytic (co)polymerization or free radical (co)polymerization, particularly from copolymers of polyethylene, polyacrylonitrile, polybutadiene, polystyrene, and at least two comonomers selected from ethylene, propylene, styrene, (meth)acrylonitrile, and 1,3-butadiene. Polypropylene is also suitable. Polyisoprene and polyacrylate are even more suitable. Polyacrylonitrile is particularly preferred.

[0064] In the context of the present invention, polyacrylonitrile is understood to mean not only polyacrylonitrile homopolymers but also copolymers of acrylonitrile with 1,3-butadiene or styrene. Polyacrylonitrile homopolymers are preferred.

[0065] In the context of the present invention, polyethylene means not only homopolyethylene but also at least 50 mol% copolymerized ethylene and 50 mol% or less of at least one further comonomer, such as α-olefins, such as propylene, butylene (1-butene), 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-pentene, and also isobutene, vinyl aromatics, such as styrene, and also (meth)acrylic acid, vinyl acetate, vinyl propionate, and C1-C of (meth)acrylic acid. 10 -Alkyl esters, particularly methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-butyl acrylate, 2-ethylhexyl acrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, and copolymers of ethylene containing maleic acid, maleic anhydride, and itaconic anhydride. Polyethylene may be HDPE or LDPE.

[0066] In the context of the present invention, polypropylene is understood to mean not only homopolypropylene but also copolymers of propylene comprising at least 50 mol% copolymerized propylene and at least one further comonomer of 50 mol% or less, such as ethylene, and α-olefins, such as butylene, 1-hexene, 1-octene, 1-decene, 1-dodecene, and 1-pentene. Polypropylene is preferably isotactic polypropylene or essentially isotactic polypropylene.

[0067] In the context of the present invention, polystyrene refers not only to styrene homopolymers, but also to acrylonitrile, 1,3-butadiene, (meth)acrylic acid, and C1-C of (meth)acrylic acid. 10 -It is understood to also mean copolymers with alkyl esters, divinylbenzene, particularly 1,3-divinylbenzene, 1,2-diphenylethylene, and α-methylstyrene.

[0068] Another preferred binder (C) is polybutadiene.

[0069] Other suitable binders (C) are selected from polyethylene oxide (PEO), cellulose, carboxymethylcellulose, polyimide, and polyvinyl alcohol.

[0070] In one embodiment of the present invention, the binder (C) has an average molecular weight M in the range of 50,000 g / mol to 1,000,000 g / mol, preferably up to 500,000 g / mol. W Selected from (co)polymers having the following properties.

[0071] The binder (C) may be a crosslinked or uncrosslinked (co)polymer.

[0072] In particularly preferred embodiments of the present invention, the binder (C) is selected from halogenated (co)polymers, particularly fluorinated (co)polymers. Halogenated or fluorinated (co)polymers are understood to mean (co)polymers comprising at least one (co)polymerized (co)monomer having at least one halogen atom or at least one fluorine atom per molecule, more preferably at least two halogen atoms or at least two fluorine atoms per molecule. Examples include 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.

[0073] Suitable binders (C) include, in particular, polyvinyl alcohol and halogenated (co)polymers, such as polyvinyl chloride or polyvinylidene chloride, and especially fluorinated (co)polymers, such as polyvinyl fluoride and especially polyvinylidene fluoride and polytetrafluoroethylene.

[0074] The cathode of the present invention may contain 1 to 15% by mass of a binder (one or more) relative to the cathode active material of the present invention. In other embodiments, the cathode of the present invention may contain 0.1 to less than 1% by mass of a binder (one or more).

[0075] A further aspect of the present invention is a battery comprising the cathode active material of the present invention, at least one cathode comprising carbon and a binder, at least one anode, and at least one electrolyte.

[0076] Embodiments of the cathode of the present invention have already been described in detail above.

[0077] The anode may contain at least one anode active material, such as carbon (graphite), TiO2, lithium titanium oxide, silicon, or tin. The anode may further contain a current collector, such as a metal foil, such as copper foil.

[0078] The electrolyte may include at least one non-aqueous solvent, at least one electrolyte salt, and optionally an additive.

[0079] The non-aqueous solvent for the electrolyte may 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.

[0080] Examples of suitable polymers include, in particular, polyalkylene glycols, preferably poly-C1-C4 alkylene glycols, and especially polyethylene glycols. Here, polyethylene glycol may contain 20 mol% or less of one or more C1-C4 alkylene glycols. The polyalkylene glycol is preferably a polyalkylene glycol having two methyl or ethyl terminal caps.

[0081] A suitable polyalkylene glycol, particularly a polyethylene glycol, has a molecular weight M W It can be at least 400 g / mol.

[0082] A suitable polyalkylene glycol, particularly a polyethylene glycol, has a molecular weight M W This can be up to 5,000,000 g / mol, preferably up to 2,000,000 g / mol.

[0083] Examples of suitable acyclic ethers include, for example, diisopropyl ether, di-n-butyl ether, 1,2-dimethoxyethane, and 1,2-diethoxyethane, with 1,2-dimethoxyethane being preferred.

[0084] Suitable examples of cyclic ethers are tetrahydrofuran and 1,4-dioxane.

[0085] Suitable examples of acyclic acetals include, for example, dimethoxymethane, diethoxymethane, 1,1-dimethoxyethane, and 1,1-diethoxyethane.

[0086] Suitable examples of cyclic acetals are 1,3-dioxane and, in particular, 1,3-dioxolane.

[0087] Suitable examples of acyclic organic carbonates include dimethyl carbonate, ethyl methyl carbonate, and diethyl carbonate.

[0088] Suitable examples of cyclic organic carbonates are compounds of general formulas (II) and (III). [ka] (In the formula, R 1 , R 2 and R 3 These can be the same or different, and are selected from hydrogen and C1-C4 alkyl groups, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl and tert-butyl, preferably R 2and R 3 (Neither of them can be tert-butyl.)

[0089] In a particularly preferred embodiment, R 1 is methyl, and R 2 and R 3 Each is either hydrogen or R 1 , R 2 and R 3 Each of these is hydrogen.

[0090] Another preferred cyclic organic carbonate is the vinylene carbonate of formula (IV).

[0091] [ka]

[0092] Preferably, the solvent or a plurality of solvents are used in a water-free state, i.e., with a water content in the range of 1 ppm to 0.1% by mass, which can be determined, for example, by Karl Fischer titration.

[0093] The electrolyte (C) further comprises at least one electrolyte salt. Preferred electrolyte salts are lithium salts in particular. Examples of preferred lithium salts are LiPF6, LiBF4, LiClO4, LiAsF6, LiCF3SO3, and LiC(C). n F 2n+1 SO2)3, lithium imide, e.g., LiN(C) n F 2n+1 SO2)2 (wherein n is an integer in the range of 1 to 20), LiN(SO2F)2, Li2SiF6, LiSbF6, LiAlCl4, and the general formula (C n F 2n+1 SO2) t YLi salt (In the formula, when Y is selected from oxygen and sulfur, t=1, When Y is selected from nitrogen and phosphorus, t=2, (If Y is selected from carbon and silicon, then t=3)

[0094] 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.

[0095] In embodiments of the present invention, the battery according to the present invention includes one or more separators by which electrodes are mechanically separated. Preferred separators are polymer films that do not react with metallic lithium, particularly porous polymer films. Particularly preferred materials for the separators are polyolefins, particularly film-forming porous polyethylene and film-forming porous polypropylene.

[0096] Separators made of polyolefins, particularly polyethylene or polypropylene, can have a porosity in the range of 35-45%. Suitable pore sizes are, for example, in the range of 30-500 nm.

[0097] In another embodiment of the present invention, the separator can be selected from a PET nonwoven fabric filled with inorganic particles. Such a separator may have a porosity in the range of 40-55%. A suitable pore size is, for example, in the range of 80-750 nm.

[0098] The battery according to the present invention further includes a housing which can have any shape, for example, a cube, or the shape of a cylindrical disk or cylindrical can. In one modified embodiment, a metal foil configured as a pouch is used as the housing.

[0099] The battery according to the present invention exhibits good cycle stability and low capacity fade.

[0100] The battery according to the present invention may include two or more electrochemical cells that are combined with each other, for example, connected in series or in parallel. Series connection is preferred. In the battery according to the present invention, at least one electrochemical cell contains at least one cathode according to the present invention. Preferably, in the electrochemical cell according to the present invention, the majority of the electrochemical cell contains cathode according to the present invention. Even more preferably, in the battery according to the present invention, all electrochemical cells contain cathode according to the present invention.

[0101] The present invention further provides a method for using the battery according to the present invention in equipment, in particular mobile equipment. Examples of mobile equipment include vehicles, such as automobiles, bicycles, aircraft, or watercraft, such as boats or ships. Other examples of mobile equipment include manually operated devices, such as computers, in particular laptops, telephones, or power tools in the construction sector, such as drills, battery-powered screwdrivers, or battery-powered staplers.

[0102] The present invention will be further explained by the following examples. [Examples]

[0103] Method explanation The amount of Li in an aqueous solution was determined by emission spectroscopy using inductively coupled plasma (ICP-OES). Equipment: ICP-OES Agilent 5100 SVDV; Wavelength: Li 670.783 nm; Internal standard: Sc 361.383 nm; Dilution factor: Li; Calibration: External.

[0104] Elemental analysis of fluorine and fluorides was performed according to a standardized method for sample preparation (discarded samples) for determining the overall fluorine content: DIN EN 14582:2016-12; the detection method was ion-selective electrode measurement. DIN 38405-D4-2:1985-07 (Water samples; digestion of inorganic solids, subsequent acid-supported distillation and determination of fluorides using ion-selective electrodes).

[0105] Starting materials: The following is "battery grade" LiOH·H2O, also known as "LiOH bg," which can be purchased from Livent and has a fluoride content of less than 5 ppm.

[0106] LiF can be purchased from Sigma Aldrich.

[0107] I. Provision of starting materials for firing I.1 Synthesis of Precursors, Process (a.1) 49 g of ammonium sulfate per 1 kg of water was added to a stirred tank reactor. The solution was heated to 55°C, and the pH was adjusted to 12 by adding an aqueous sodium hydroxide solution.

[0108] The coprecipitation reaction was initiated by simultaneously supplying aqueous solutions of transition metal sulfate and sodium hydroxide at a flow rate ratio of 1.8, with a total flow rate of 8 hours. The transition metal solution contained Ni, Co, and Mn in a molar ratio of 8.3:1.2:0.5 and a total transition metal concentration of 1.65 mol / kg. The sodium hydroxide solution consisted of a 25% by mass sodium hydroxide solution and a 25% by mass ammonia solution in a mass ratio of 6. The pH value was maintained at 12 by supplying an additional sodium hydroxide solution. The mother liquor was continuously collected starting from the initiation of all feeds. After 33 hours, all feed flows were stopped. The resulting suspension was filtered, washed with distilled water, dried in air at 120°C, and sieved to obtain the mixed transition metal (TM) oxyhydroxide precursor TM-OH.1.

[0109] I.2 Synthesis of LiOH containing LiF, step (b.1) Approximately 1 ton of mechanically processed battery scrap containing spent cathode active material including nickel, cobalt, and manganese, organic carbon in the form of flux and soot, residual electrolyte, and further impurities including fluorine compounds, phosphorus, and calcium, was processed according to the process described by Jia Li et al., Journal of Hazardous Materials 2016, 302, 97-104, to obtain reduced lumps. The atmosphere in the roasting system was air in which oxygen reacts with carbon in the battery scrap to form carbon monoxide, and the processing temperature was 800°C.

[0110] After the reaction, the material was cooled to room temperature, recovered from the furnace, and mechanically processed to obtain particulate matter. This particulate matter was then analyzed by powder X-ray diffraction, elemental analysis, and particle size distribution.

[0111] The Li content was 3.6% by mass, which serves as a reference for the leaching procedure below. Fluorine (2.6% by mass) is mainly represented as inorganic fluoride (2.3% by mass). The particle size was less than 1 mm; the determined D50 was 17.36 μm.

[0112] The obtained XRD pattern is used to calculate the reference pattern of Ni (Co x Ni 1-x When compared with (x=0~0.6, which is identical to one of Co, Li2CO3, or LiAlO2), it can be concluded that Ni exists only as a metallic phase, pure Ni, or an alloy combined with Co. The whole sample exhibits typical ferromagnetic behavior when in contact with a permanent magnetic material. As lithium salts, Li2CO3 and LiAlO2 are clearly distinguishable by their characteristic diffraction patterns.

[0113] Leaching of heat-treated black lumps with Ca(OH)2: 30 g of the above heat-treated battery scrap material and 9 g of solid Ca(OH)2 were placed in a PFA flask. The solids were mixed. Next, 200 g of water was added while stirring, and the entire mixture was refluxed for 6 hours. After 6 hours, the solids were filtered, and a filtrate sample was taken and analyzed for Li (c(Li) = 0.49 mass%) and F (c(F) = 0.015 mass%).

[0114] Solid LiOH from the filtrate of leached LiOH Subsequently, the filtrate obtained in the above experiment was dried to obtain solid LiOH as a monohydrate, which contains fluoride. Two different procedures were applied to adjust the fluoride content.

[0115] (A) Water was completely evaporated (40°C, 42 mg) from a 150 mL filtrate containing 0.49 mass% lithium and 0.015 mass% fluoride to obtain LiOH·LiF.1. XRD of LiOH·LiF.1 revealed a small amount of Li2CO3 impurity. The latter was attributed to contact with air for most of the process steps. Following carbon-based impurities, elemental analysis revealed that fluoride was one of the main impurities (c(F) = 0.5 mass%).

[0116] (B) Another 150 mL filtrate from another LiOH leaching experiment containing 0.49 mass% lithium and 0.015 mass% fluoride was concentrated sixfold by evaporation (40°C, 42 mg bar) (c(Li) = 2.94 mass%), filtered, and finally dried for 24 hours at 40°C with a constant flow rate of nitrogen. XRD of LiOH·LiF.2 revealed small amounts of Li2CO3 impurities. The latter was attributed to contact with air for most of the process steps. Following carbon-based impurities, elemental analysis revealed fluoride to be one of the main impurities (c(F) = 0.25 mass%).

[0117] I.3 Synthesis of Li2CO3 containing fluoride, process (b.2) CO2 was introduced into a LiOH solution containing 2.6 mass% lithium and 0.017 mass% fluoride for 7 hours (under ambient conditions, ~5 L / h). A white solid was immediately visible. After 7 hours, the solid was filtered, dried, and subjected to XRD and elemental analysis (Li = 19.0 mass%, F = 0.22 mass%).

[0118] II. Production of Cathode Active Material II.1 Mixing process, process (c.1) and firing process (d.1) Step (c.1): Using a Kinematica Microtron laboratory mixer, the precursors TM-OH.1, LiOH·LiF.1, and Al2O3 (average crystallite size 6 nm) were mixed for 1 minute three times at molar ratios of Al / (Ni+Co+Mn)=0.01 and Li / Ni+Co+Mn+Al=1.02:1.

[0119] Step (d.1): The mixture from step (c.1) was heated to 780°C and held under a forced flow of oxygen for 6 hours. After cooling to room temperature, the resulting powder was deaggregated and sieved through a 32 μm mesh. CAM.1 was obtained. No fluoride accumulation was detected.

[0120] The D50, determined using laser diffraction techniques with a Mastersize 3000 instrument from Malvern Instruments, was 12 μm. Li and transition metal content was determined by ICP analysis. Residual moisture content, determined at 250°C, was less than 300 ppm.

[0121] Electrochemical tests were performed on a coin half-cell, demonstrating excellent first-cycle discharge capacity and cycle stability.

[0122] II.2 Production of Cathode Active Material CAM.2 We used "battery-grade" LiOH·H2O, also referred to hereafter as "LiOH bg," which is available from Livent and has a fluoride content of less than 5 ppm, to replace a portion of LiOH·LiF.1.

[0123] Step (c.2): Using a Kinematica Microtron laboratory mixer, the precursor TM-OH.1, a mixture of LiOH bg and LiOH·LiF.1, and Al2O3 (average crystallite size 6 nm) were mixed for 1 minute three times at a molar ratio of Al / (Ni+Co+Mn)=0.01 and Li / Ni+Co+Mn+Al=1.02:1. The mass ratio of LiOH bg to LiOH·LiF.1 was 1:1. A mixture was obtained.

[0124] Step (d.2): Step (d.1) was repeated, but the mixture obtained from step (c.2) was used. After cooling to room temperature, the obtained powder was deaggregated and sieved through a 32 μm mesh. CAM.2 was obtained. No fluoride accumulation was detected.

[0125] Electrochemical tests were performed on a coin half-cell, demonstrating excellent first-cycle discharge capacity and cycle stability.

[0126] II.3 Preparation of Comparative Cathode Active Material C-CAM.3 Comparative process C-(b.3): To correspond to CAM.1, LiOH·H2O b.g. was mixed with LiF in a mass ratio of 99.66:0.34. A premix was obtained. As can be seen from the crystals, the premix still contained LiF crystals.

[0127] Comparative step C-(c.3): Using a Kinematica Microtron laboratory mixer, the premix from precursor TM-OH.1 and C-(b.3) and Al2O3 (average crystallite size 6 nm) were mixed for 1 minute three times at molar ratios of Al / (Ni+Co+Mn)=0.01 and Li / Ni+Co+Mn+Al=1.02:1. A mixture was obtained.

[0128] Step C-(d.3): Step (d.1) was repeated, but the mixture obtained from step C-(c.3) was used. After cooling to room temperature, the obtained powder was deaggregated and sieved through a 32 μm mesh. C-CAM.3 was obtained. Multiple C-CAM.3 samples showed different indeterminate behavior compared to CAM.1 and CAM.2.

[0129] III. Testing of Cathode Active Materials III.1 Cathode Manufacturing, General Procedure For the cathode, a PVDF binder (Solef® 5130) was dissolved in NMP (Merck) to prepare a 7.5% by mass solution. For electrode preparation, the binder solution (3% by mass) and carbon black (Super C65, 3% by mass) were suspended in NMP. After mixing using a planetary centrifugal mixer (ARE-250, Thinky Corp.; Japan), the CAM of the present invention (or comparative CAM) (94% by mass) was added, and the suspension was mixed again to obtain a lump-free slurry. The solid content of the slurry was adjusted to 61%. The slurry was coated onto Al foil using a KTF-S roll-to-roll coater (Mathis AG). Before use, all electrodes were calendered. The cathode material thickness was 100 μm, and the concentration was 6.5 mg / cm². 2 This was addressed. Before assembling the battery, all electrodes were dried at 105°C for 7 hours.

[0130] III.2 Electrolyte Preparation A base electrolyte composition (EL base 1) containing ethylene carbonate and ethyl methyl carbonate in a mass ratio of 3:7 was prepared.

[0131] II.3 Manufacturing of Test Cells Coin-shaped half-cells (20 mm in diameter, 3.2 mm thick) containing the cathode prepared as described in III.1 and lithium metal as the working electrode and counter electrode were assembled and sealed in a glove box filled with Ar. Furthermore, half-coin cells were fabricated by stacking the cathode, anode, and separator in the order of cathode / / separator / / Li foil. Subsequently, 0.15 mL of EL base 1 as described in (II.2) above was introduced into these coin cells.

[0132] IV. Evaluation of Cell Performance Evaluation of Coin Half Cell Performance We evaluated the cell performance using the manufactured coin-type batteries.

[0133] Initial performance and rate performance were measured as follows: Coin half-cells according to III.3 were tested at 25°C in a voltage range of 4.3V to 3.0V. In the initial cycle, charging and discharging were performed in CC mode. That is, a constant current (CC) of 0.1C was applied until the voltage reached 4.3V during charging, or until the voltage reached 3.0V during discharging. After the initial formation cycle, the rate characteristics were measured in CC mode with a constant discharge current of 3C.

[0134] The cycle performance and resistance growth were tested as follows: After initial performance evaluation, the coin cell was cycled for 100 cycles at 25°C with a constant 0.5C charge current and a constant 1C discharge current. Resistance growth was measured by measuring the voltage drop after 30 seconds at the start of each discharge cycle.

[0135] The batteries based on the cathode active material of the present invention are superior. In particular, CAM.1 and CAM.2 show improved cycle stability and reduced resistance growth compared to C-CAM.3. Specifically, several C-CAM.3 samples exhibited entirely different electrochemical behavior. While we do not wish to be bound by any theory, we assume that some C-CAM.3 samples contain fluoride, while others do not.

Claims

1. General formula Li １＋ｘ TM １－ｘ O ２－ｙ F ｙ A particulate cathode active material having an average particle size (D50) in the range of 3 to 16 μm, wherein TM comprises Ni and at least one of Mn and Co, and TM is of general formula (I) (Ni a Co b Mr c ) 1-d M d (I) (In the formula, a is in the range of 0.6 to 0.99, b is 0 or in the range of 0.01 to 0.

2. c is in the range of 0 to 0.

2. d is in the range of 0 to 0.

1. M is at least one of Al, Mg, Ti, Mo, Nb, Ta, W, and Zr. a + b + c = 1) A particulate cathode active material in which a combination of metals is obtained, x is in the range of 0 to 0.2, y is in the range of 0.0002 to 0.03, and F is uniformly dispersed in this cathode active material.

2. (A) At least one particulate cathode active material according to claim 1, (B) Conductive carbon, (C) Binder material A cathode containing this substance.

3. (1) at least one cathode according to claim 2, (2) at least one anode, and (3) at least one type of electrolyte A battery containing [something].

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