Method for producing coated cathode active material, and coated cathode active material

Abstract

1. A method for producing a coated electrode active material, the method comprising the steps of: (a) General formula Li 1+x TM 1-x O 2 wherein T is Ni or a combination of metals according to formula (I), x is in the range of 0 to 0.2, and the water content is in the range of 500 to 1500 ppm. (Ni a Co b Mn c ) 1-d M d (I) (In the formula, a is in the range of 0.3 to 0.4, b is in the range of 0 to 0.1; c is in the range of 0.6 to 0.7; d is in the range of 0 to 0.1; M is Al, Ti, Zr, or Mg; a+b+c=1; (b) reacting the electrode active material with a silicon alkoxide and an alkylaluminum compound in one or more substeps; (c) heat-treating the material thus obtained in an oxygen-containing atmosphere at a temperature in the range of 100 to 400° C. for 10 minutes to 4 hours; Includes.

Description

[Technical field]

[0001] The present invention relates to a method for producing a coated electrode active material, the method comprising the steps of: (a) General formula Li 1+x TM 1-x Providing an electrode active material with O2, wherein T is Ni or a combination of metals according to formula (I), x is in the range of 0-0.2, and the water content is in the range of 500-1500 ppm. (Ni a Co b Mn c ) 1-d M d (I) (In the formula, a is in the range of 0.3 to 0.4, b is in the range of 0 to 0.1; c is in the range of 0.6 to 0.7; d is in the range of 0 to 0.1; M is Al, Ti, Zr, or Mg; a+b+c=1; (b) reacting the electrode active material with a silicon alkoxide and an alkylaluminum compound in one or more substeps; (c) heat-treating the material thus obtained in an oxygen-containing atmosphere at a temperature in the range of 100 to 400° C. for 10 minutes to 4 hours; Includes.

[0002] Furthermore, the present invention relates to a Ni-rich electrode active material. [Background technology]

[0003] Lithium-ion secondary batteries are modern devices for storing energy. 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 have important roles in the performance of the battery. Cathode materials have received particular attention. Several materials have been proposed, such as lithium iron phosphate, lithium cobalt oxide, and lithium nickel cobalt manganese oxide. Extensive research has been conducted, but the solutions found so far still leave room for improvement.

[0004] Currently, particular interest is observed in so-called Ni-rich electrode active materials, for example electrode active materials containing 75 mol % or more of Ni with respect to the total TM content.

[0005] One problem with lithium-ion batteries, especially with Ni-rich electrode active materials, is due to undesirable reactions at the surface of the electrode active material. Such reactions can be the decomposition of the electrolyte or the solvent or both. Therefore, attempts have been made to protect the surface without preventing lithium exchange during charging and discharging. Examples are attempts to coat the electrode active material with, for example, aluminum oxide or calcium oxide (see, for example, US 8,993,051).

[0006] Another theory is that the undesired reaction is assigned to free LiOH or Li2CO3 on the surface. Attempts have been made to remove such free LiOH or Li2CO3 by washing the electrode active material with water (see, for example, JP 4,789,066 B, JP 5,139,024 B, and US2015 / 0372300). However, in some cases, it has been observed that the properties of the obtained electrode active material are not improved. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] US 8,993,051 [Patent Document 2] JP 4,789,066 B [Patent Document 3] JP 5,139,024 B [Patent Document 4] US2015 / 0372300 Summary of the Invention [Problem to be solved by the invention]

[0008] The object of the present invention was to provide a method for producing an electrode active material having excellent electrochemical properties. In particular, the object of the present invention was to provide a so-called Ni-rich electrode active material having excellent electrochemical properties. [Means for solving the problem]

[0009] Thus, a method as defined at the outset has been found, hereinafter also referred to as the "method of the invention", which comprises at least three steps, namely step (a), step (b) and step (c), which are explained in more detail below. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Step (a) is a compound of the general formula Li 1+x TM 1-x providing an electrode active material with O2, wherein TM is Ni, or a combination of metals according to formula (I), (Ni a Co b Mn c ) 1-d M d (I) (In the formula, a is in the range of 0.3 to 0.4, b is in the range of 0 to 0.1; c is in the range of 0.6 to 0.7; d is in the range of 0 to 0.1; M is Al, Ti, Zr, or Mg; a+b+c=1) For example, a combination of Ni and Mn, preferably a combination of Ni, Co and Mn, and optionally at least one metal selected from Mg, Ti and Zr, where x is in the range of 0-0.2, preferably 0.01-0.05, and the water content is in the range of 500-1500 ppm, preferably 1000-1200 ppm. At least 60 mol % of TM is manganese.

[0011] The water content can be determined by Karl Fischer titration.

[0012] In one embodiment of the present invention, the particulate material has an average particle size (D50) in the range of 3 to 20 μm, preferably 5 to 16 μm. The average particle size can be determined, for example, by light scattering or laser diffraction. The particles are usually composed of aggregates from primary particles, and the particle size mentioned above refers to the particle size of the secondary particles.

[0013] In one embodiment of the present invention, the particulate matter has a particle size of 0.1 to 1.5 m 2 / g. The BET surface area can be determined by nitrogen adsorption after outgassing the sample at 200 °C for 30 minutes and beyond, according to DIN ISO 9277:2010.

[0014] Li 1+x TM 1-x The variable x in O2 and TM corresponding to formula (I) is preferably in the range of 0.05 to 0.2, more preferably 0.1 to 0.15.

[0015] The electrode active material provided in step (a) is typically free of conductive carbon, i.e. the conductive carbon content of the starting material is less than 1% by mass, preferably 0.001 to 1.0% by mass, and even more preferably below the detection level, based on said starting material.

[0016] Some elements are ubiquitous. In the context of the present invention, trace amounts of ubiquitous metals such as sodium, calcium, iron or zinc as impurities are not taken into account in the present specification. Trace amounts in this context mean amounts of 0.02 mol % or less, based on the total metal content of the starting material. Trace amounts of sulfates are also ignored.

[0017] The electrode active material provided in step (a) has a water content in the range of 500-1500 ppm, preferably 1000-1200 ppm, where ppm is parts per million by mass. Such water can be introduced by treating the electrode material with a water-containing solvent. Preferably, said solvent has a boiling point below 100°C. Examples include water-containing C1-C3-alkanols, such as isopropanol, ethanol, n-propanol, and especially methanol.

[0018] In one embodiment of the present invention, the water-containing solvent has a water content in the range of 0.05 to 5% by volume, preferably 0.1 to 0.5% by volume.

[0019] In one embodiment of the present invention, the volume ratio of the aqueous solvent to the electrode active material provided in step (a) is in the range of 1:1 to 1:10. The larger the amount of solvent, the more effort it takes to remove the solvent. If the amount of solvent is too small, the treatment with moisture may be unbalanced, and some of the electrode active material provided in step (a) may not contain moisture, while other electrode active material provided in step (a) may remain treated with moisture.

[0020] The solvent is removed after treatment, for example by filtration or evaporation. During the evaporation process, it is advantageous to avoid harsh conditions such as drying at 120° C. Evaporation at reduced pressure, for example 1 to 200 mbar (abs), is preferred.

[0021] In another embodiment, the moisture content is achieved by storage in a humid atmosphere.

[0022] In step (b), the electrode active material is reacted with a silicon alkoxide and an alkylaluminum compound in one or more substeps, preferably in one step.

[0023] Examples of silicon alkoxides include C1-C4-alkoxides such as Si(OCH3)4, Si(OC2H5)4, Si(On-C3H7)4, Si(O-iso-C3H7)4, Si(On-C4H9)4, and combinations of at least two of the above, with Si(OCH3)4 and Si(OC2H5)4 being preferred. Intermediates formed by partial hydrolysis of any of the above C1-C4-alkoxides of silicon, such as, but not limited to, disilicon compounds such as (CH3O)3Si-O-Si(OCH3)3 and (C2H5O)3Si-O-Si(OC2H5)3, can also react with the electrode active material.

[0024] Examples of alkylaluminum compounds include tri-C1-C4-alkyl compounds of Al, such as methyldiisopropylaluminum, triisopropylaluminum, d-tri-n-butylaluminum, ethyldimethylaluminum, trimethylaluminum and triethylaluminum, in particular trimethylaluminum. Methylalumoxane, which may be formed as an intermediate, is also a possible reaction partner.

[0025] In one embodiment of the present invention, the molar ratio of silicon to aluminum in the silicon alkoxide and trialkylaluminum compound in step (b) is in the range of 1:10 to 10:1, preferably 1:3 to 3:1. This ratio corresponds to the ratio of silicon alkoxide to trialkylaluminum compound employed in step (b). It is observed that trialkylaluminum compounds are often more reactive than silicon alkoxides, and unreacted silicon alkoxide may be removed after the reaction in step (b) is apparently complete.

[0026] In one embodiment of the present invention, the amount of silicon alkoxide and alkylaluminum compound is each in the range of 1 to 30 per kg of the electrode active material provided in step (a).

[0027] In a preferred embodiment of the present invention, the duration of step (b) ranges from 1 second to 2 hours, preferably from 1 second to 10 minutes.

[0028] In one embodiment of the present invention, step (b) is carried out at a temperature in the range of 5°C to 85°C, preferably 15 to 40°C.

[0029] In one embodiment of the invention, step (b) is carried out without a solvent, the silicon alkoxide and trialkylaluminum are evaporated, and then the electrode material provided in step (a) is exposed to the evaporated silicon alkoxide and trialkylaluminum.

[0030] In a preferred embodiment of the present invention, step (b) is carried out in the presence of at least one organic solvent.Depending on the nature of the reactants, such organic solvent is preferably aprotic and halogen-free.Preferably, a hydrocarbon, such as an alkane, cycloalkane, or aromatic hydrocarbon, n-hexane, n-heptane, n-octane, isooctane, cyclohexane, cycloheptane, in particular an aromatic hydrocarbon, such as toluene, ethylbenzene, ortho-xylene, meta-xylene, and an isomeric mixture of at least two of the three xylenes, is selected as the solvent.

[0031] In one embodiment of the present invention, the ratio of solvent to electrode active material provided in step (a) is in the range of 0.1-4 ml / g.

[0032] Step (b) may be carried out in one step or in two or more substeps, with one step being preferred. The substeps may include a first substep of treating with silicon alkoxide and a second substep of treating with trialkylaluminum. In another embodiment, the first substep of treating with trialkylaluminum is carried out and the second substep of treating with silicon alkoxide is carried out. However, preferably, the treatment with silicon alkoxide and trimethylaluminum compound is carried out simultaneously.

[0033] The pressure at which step (b) is carried out is not critical, particularly when carried out in the presence of a solvent. For practical purposes, normal pressure is preferred.

[0034] After step (b), the solvent (if present) and by-products such as alcohols and alkanes are preferably removed by evaporation. The conditions for evaporating such solvents depend on their volatility. The temperature may range from 50 to 150° C. and the pressure may range from 1 mbar to 500 mbar.

[0035] The resulting material is then subjected to step (c).

[0036] In step (c) of the method of the present invention, the material thus obtained is heat treated in an oxygen-containing atmosphere at a temperature in the range of 100-400° C. for 10 minutes to 4 hours.

[0037] Step (c) can be carried out in any type of oven, such as a roller hearth kiln, a pusher kiln, a rotary kiln, a pendulum kiln, or, in the case of laboratory scale tests, a muffle oven.

[0038] The temperature of the heat treatment in step (c) may be in the range of 100 to 400° C., preferably 250 to 350° C. The said temperature refers to the maximum temperature in step (c).

[0039] In one embodiment of the present invention, the temperature is increased before reaching the desired temperature of 100° C. to 400° C. For example, the material obtained in step (b) is first heated to 75 to 90° C., kept constant for 10 minutes to 0.5 hours, and then heated to 100 to 400° C.

[0040] In one embodiment of the present invention, the heating rate in step (c) is in the range of 0.1 to 10° C. / min.

[0041] In one embodiment of the present invention, step (c) is carried out in a roller hearth kiln, a pusher kiln or a rotary kiln, or a combination of at least two of them. A rotary kiln has the advantage that the homogenization of the material produced therein is very good. In roller hearth kilns and pusher kilns, different reaction conditions for different steps can be set very easily. In laboratory scale experiments, box furnaces, tube furnaces and split tube furnaces can also be used.

[0042] In one embodiment of the present invention, step (c) is carried out in an oxygen-containing atmosphere, such as a nitrogen-air mixture, a noble gas-oxygen mixture, air, oxygen, oxygen-enriched air, or pure oxygen. In a preferred embodiment, the atmosphere of step (c) is selected from air, oxygen, and oxygen-enriched air. The oxygen-enriched air may be, for example, a 50:50 volumetric mixture of air and oxygen. Other options are a 1:2 volumetric mixture of air and oxygen, a 1:3 volumetric mixture of air and oxygen, a 2:1 volumetric mixture of air and oxygen, and a 3:1 volumetric mixture of air and oxygen. Pure oxygen is even more preferred.

[0043] In one embodiment of the invention, step (c) has a duration ranging from 10 minutes to 4 hours. Preferably, it is from 60 minutes to 3 hours. Cooling times are ignored in this context.

[0044] By carrying out the method of the present invention, a coated electrode active material having excellent electrochemical properties is obtained. Without wishing to be bound by any theory, it is assumed that the decomposition products of the silicon alkoxy compound and the trialkylaluminum compound form a layer of a compound capable of scavenging HF and are deposited on the surface of the electrode active material. In the context of the present invention, the coated electrode active material obtained refers to at least 80% of the particles of a batch of particulate cathode active material being coated, and at least 75%, for example 75-99.99%, preferably 80-90% of the surface of each particle being coated.

[0045] They exhibit excellent electrochemical properties.

[0046] In a particular embodiment of the present invention, in step (b) or in a sub-step before or after step (b), a cobalt carbonyl or organometallic compound is applied to the electrode active material provided in step (a) or obtained from step (b). The term "cobalt carbonyl compound" refers to a compound that is a CO complex of cobalt, with or without additional ligands. Examples of such cobalt carbonyl compounds include Co2(CO)8, Co(CO)3NO, Co(CO)3CF3, [Co(CO)3](Co-C1-C4-alkyl)2, and HCo(CO)3. Examples of cobalt organometallic compounds include [(η 5 -Cp)2Co], where Cp is cyclopentadienyl, η 5 -CpCo(CO)2, [Co(η 3 -allyl)(CO)3], and η 5 -Cp-Co-bisamidinate. 5 Some compounds, such as -CpCo(CO)2, qualify as both carbonyl compounds and organometallic compounds of cobalt.

[0047] Depending on the type of ligand, cobalt can be deposited as Co(0) or in an oxidation state higher than zero.

[0048] In one embodiment of the present invention, 1 to 5% by weight of Co is optionally deposited on the electrode active material provided in step (a) or obtained from step (b).

[0049] A further aspect of the present invention relates to a coated particulate material, hereinafter also referred to as inventive cathode active material or inventive particulate material or inventive coated particulate material.

[0050] In the context of the present invention, a coated particulate material of the invention means that at least 80% of the particles of a batch of particulate material are coated, with at least 75%, for example 75-99.99%, preferably 80-90%, of the surface of each particle being coated.

[0051] The thickness of such coatings may be very thin, for example 0.1-5 nm. In other embodiments, the thickness may be in the range of 6-15 nm. In further embodiments, the thickness of such coatings is in the range of 16-50 nm. Thickness in this context refers to the amount of metal alkoxide and alkylmetal compound per particle surface m 2 and assuming 100% conversion in step (b).

[0052] Without wishing to be bound by any theory, it is believed that the uncoated portions of the particles do not react due to the particular chemical properties of the particles, for example, the density of chemically reactive groups such as, but not limited to, hydroxyl groups, chemically restricted oxide moieties, or adsorbed water.

[0053] In one embodiment of the present invention, the coated particulate material of the present invention has an average particle size (D50) in the range of 3 to 20 μm, preferably 5 to 16 μm. The average particle size can be determined, for example, by light scattering or laser diffraction. The particles are usually composed of aggregates from primary particles, and the particle size mentioned above refers to the particle size of the secondary particles.

[0054] In one embodiment of the present invention, the coated particulate material of the present invention has a diameter of 0.1 to 1.5 mm. 2 / g. The BET surface area can be determined by nitrogen adsorption after outgassing the sample at 200 °C for 30 minutes and beyond, according to DIN ISO 9277:2010.

[0055] The coated particulate material of the present invention has the general formula Li 1+x TM 1-x The present invention relates to a method for producing a ceramic ceramic substrate comprising the steps of: (a) a core material having a thickness of 100 nm and a thickness of 100 nm; (b) a mixed oxide of aluminum and silicon having a thickness of 100 nm; and (c) a core material having a thickness of 100 nm and a thickness of 100 nm. The present invention relates to a ceramic substrate having a thickness of 100 nm and a thickness of 100 nm.

[0056] The term "uniform composition" is intended to indicate that the coating appears without compositional variation throughout each particle when viewed, for example, by EDX (energy dispersive X-ray spectroscopy) mapping, rather than being arranged in distinct layers. "Uniform composition" is intended to include a mixture of two or more compounds having a uniform ratio.

[0057] In one embodiment of the invention, the coating comprises a compound selected from Li4SiO4, Li2SiO3 and Li2Si3O7, and a compound selected from LiAlSiO4 and LiAlSi2O6.

[0058] In one embodiment of the invention, the coating comprises a combination of at least two compounds selected from Al2O3, SiO2, Li4SiO4, Li2SiO3, Li2Si3O7, LiAlSiO4 and LiAlSi2O6, at least one of which contains lithium, in such combinations at least one compound contains Al and at least one contains Si.

[0059] TM is a compound represented by the formula (I), (Ni a Co b Mn c ) 1-d M d (I) (In the formula, a is in the range of 0.3 to 0.4, b is in the range of 0 to 0.1; c is in the range of 0.6 to 0.7; d is in the range of 0 to 0.1; M is Al, Ti, Zr, or Mg; a+b+c=1) It is a combination of metals.

[0060] In one embodiment of the present invention, the molar ratio of silicon to aluminum in the coating ranges from 1:20 to 1:1, preferably from 1:20 to 1:5.

[0061] The cathode active material of the present invention can be obtained by the method of the present invention. Without wishing to be bound by any theory, it is hypothesized that due to the different reactivities of silicon alkoxide and alkylaluminum compound towards the wet electrode active material as provided in step (a), a higher percentage of trialkylaluminum is precipitated and a higher percentage of unreacted silicon alkoxide is lost and removed.

[0062] The cathode active materials of the present invention exhibit excellent properties, particularly with respect to cycling stability and low capacity fade.

[0063] A further aspect of the present invention refers to electrodes comprising at least one electrode active material according to the present invention. These are particularly useful for lithium-ion batteries. Lithium-ion batteries comprising at least one electrode according to the present invention show good discharge behavior. An electrode comprising at least one electrode active material according to the present invention is hereinafter also called the cathode of the present invention or the cathode of the present invention.

[0064] In particular, the cathode of the present invention comprises (A) at least one electrode active material of the present invention; (B) Carbon in a conductive state; (C) a binder polymer, also called binder (C) or (C), and preferably (D) Current collector Contains:

[0065] In a preferred embodiment, the cathode of the present invention comprises, based on the sum of (A), (B) and (C), (A) 80 to 98 mass % of the electrode active material of the present invention, (B) 1 to 17 mass% carbon, (C) 1 to 15% by mass of a binder polymer Contains:

[0066] The cathodes according to the present invention may include additional components. They may include a current collector, such as, but not limited to, aluminum foil. They may further include conductive carbon and a binder.

[0067] The cathode according to the present invention contains a conductively modified carbon, also called carbon (B) for short, which can be selected from soot, activated carbon, carbon nanotubes, graphene, and graphite, and combinations of at least two of the above.

[0068] Suitable binders (C) are 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, in particular 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. Polyisoprene and polyacrylates are furthermore suitable. Polyacrylonitrile is particularly preferred.

[0069] 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 with styrene. Polyacrylonitrile homopolymers are preferred.

[0070] In the context of the present invention, polyethylene refers not only to homopolyethylenes, but also to copolymerized ethylene with at least 50 mol % and up to 50 mol % 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, C1-C2 copolymers of (meth)acrylic acid. 10 -alkyl esters, in particular methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-butyl acrylate, 2-ethylhexyl acrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, and also copolymers of ethylene with maleic acid, maleic anhydride and itaconic anhydride. The polyethylene may be HDPE or LDPE.

[0071] In the context of the present invention, polypropylene is understood to mean not only homopolypropylene but also copolymers of propylene with at least 50 mol % copolymerized propylene and up to 50 mol % of at least one further comonomer, such as ethylene, and α-olefins, such as butylene, 1-hexene, 1-octene, 1-decene, 1-dodecene and 1-pentene. The polypropylene is preferably isotactic polypropylene or essentially isotactic polypropylene.

[0072] In the context of the present invention, polystyrene refers not only to homopolymers of styrene, but also to C1-C4 copolymers of acrylonitrile, 1,3-butadiene, (meth)acrylic acid, and (meth)acrylic acid. 10-alkyl esters, divinylbenzene, in particular 1,3-divinylbenzene, 1,2-diphenylethylene and α-methylstyrene copolymers are also understood to mean.

[0073] Another preferred binder (C) is polybutadiene.

[0074] Other suitable binders (C) are selected from polyethylene oxide (PEO), cellulose, carboxymethyl cellulose, polyimides and polyvinyl alcohol.

[0075] In one embodiment of the invention, the binder (C) has an average molecular weight M ranging from 50,000 g / mol to 1,000,000 g / mol, preferably up to 500,000 g / mol. W The (co)polymers are selected from those having the formula:

[0076] The binder (C) may be a crosslinked or non-crosslinked (co)polymer.

[0077] In a particularly preferred embodiment of the present invention, the binder (C) is selected from halogenated (co)polymers, in particular fluorinated (co)polymers.Halogenated or fluorinated (co)polymers are understood to mean (co)polymers that contain at least one (co)polymerized (co)monomer with 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.

[0078] Suitable binders (C) are especially polyvinyl alcohol and halogenated (co)polymers such as polyvinyl chloride or polyvinylidene chloride, especially fluorinated (co)polymers such as polyvinyl fluoride and especially polyvinylidene fluoride and polytetrafluoroethylene.

[0079] The cathode of the present invention may comprise 1 to 15% by weight of binder(s) relative to the electrode active material. In another embodiment, the cathode of the present invention may comprise 0.1 to less than 1% by weight of binder(s).

[0080] A further aspect of the invention is a battery containing at least one cathode comprising the electrode active material of the invention, carbon, and a binder, at least one anode, and at least one electrolyte.

[0081] The cathode embodiments of the present invention have already been described in detail above.

[0082] 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.

[0083] The electrolyte may include at least one non-aqueous solvent, at least one electrolyte salt, and optionally, additives.

[0084] 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.

[0085] Examples of suitable polymers are in particular polyalkylene glycols, preferably poly-C1-C4-alkylene glycols and in particular polyethylene glycols, where the polyethylene glycols may contain up to 20 mol % of one or more C1-C4-alkylene glycols.The polyalkylene glycols are preferably polyalkylene glycols with two methyl or ethyl end caps.

[0086] The molecular weight M of suitable polyalkylene glycols, particularly suitable polyethylene glycols, W may be at least 400 g / mol.

[0087] The molecular weight M of suitable polyalkylene glycols, particularly suitable polyethylene glycols, W can be up to 5,000,000 g / mol, preferably up to 2,000,000 g / mol.

[0088] Examples of suitable acyclic ethers are, for example, diisopropyl ether, di-n-butyl ether, 1,2-dimethoxyethane, 1,2-diethoxyethane, with 1,2-dimethoxyethane being preferred.

[0089] Examples of suitable cyclic ethers are tetrahydrofuran and 1,4-dioxane.

[0090] Examples of suitable acyclic acetals are, for example, dimethoxymethane, diethoxymethane, 1,1-dimethoxyethane and 1,1-diethoxyethane.

[0091] An example of a suitable cyclic acetal is 1,3-dioxane, and especially 1,3-dioxolane.

[0092] Examples of suitable acyclic organic carbonates are dimethyl carbonate, ethyl methyl carbonate, and diethyl carbonate.

[0093] Examples of suitable cyclic organic carbonates are compounds according to general formulae (II) and (III) [ka] (In the formula, R 1 , R 2 and R 3 can be the same or different and are selected from hydrogen and C1-C4-alkyl, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl and tert-butyl, preferably R 2 and R 3 (Both cannot be tert-butyl).

[0094] In a particularly preferred embodiment, R 1 is methyl, R 2 and R 3 are each hydrogen or R 1 , R 2 and R 3 are hydrogen.

[0095] Another preferred cyclic organic carbonate is vinylene carbonate of formula (IV).

[0096] [ka]

[0097] Preferably, the solvent or solvents are used in an aqueous state, ie with a water content in the range of 1 ppm to 0.1% by weight, which can be determined, for example, by Karl Fischer titration.

[0098] The electrolyte 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, 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 ranging from 1 to 20), LiN(SO2F)2, Li2SiF6, LiSbF6, LiAlCl4, and compounds of the general formula (C n F 2n+1 SO2) t Salt of YLi where t=1 when Y is selected from oxygen and sulfur; when Y is selected from nitrogen and phosphorus, t=2; When Y is selected from carbon and silicon, t=3).

[0099] Preferred electrolyte salts are selected from LiC(CF3SO2)3, LiN(CF3SO2)2, LiPF6, LiBF4, LiClO4, with LiPF6 and LiN(CF3SO2)2 being particularly preferred.

[0100] In one embodiment of the present invention, the battery according to the present invention comprises one or more separators by which the electrodes are mechanically separated.Suitable separators are polymer films, especially porous polymer films, that are unreactive towards metallic lithium.Particularly suitable materials for the separators are polyolefins, especially film-forming porous polyethylene and film-forming porous polypropylene.

[0101] A separator made of polyolefin, particularly polyethylene or polypropylene, may have a porosity in the range of 35 to 45%. A suitable pore size is, for example, in the range of 30 to 500 nm.

[0102] In another embodiment of the present invention, the separator can be selected from PET nonwoven fabrics filled with inorganic particles. Such separators can have a porosity in the range of 40-55%. Suitable pore sizes are, for example, in the range of 80-750 nm.

[0103] The battery according to the invention may further comprise a housing which may have any shape, for example a cube, or the shape of a cylindrical disk or can. In one variant, a metal foil configured as a pouch is used as the housing.

[0104] The battery according to the invention exhibits, for example, good discharge behavior at low temperatures (below 0° C., for example down to −10° C. or less), very good discharge and cycling behavior.

[0105] The battery according to the present invention may comprise two or more electrochemical cells that are combined with each other, for example, connected in series or connected in parallel. A 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 cells contain the cathode according to the present invention. Even more preferably, in the battery according to the present invention, all the electrochemical cells contain the cathode according to the present invention.

[0106] The present invention further provides a method for using the battery according to the present invention in equipment, especially mobile equipment.Examples of mobile equipment are vehicles, such as automobiles, bicycles, aircraft, or water vehicles, such as boats or ships.Other examples of mobile equipment are manually operated, such as computers, especially laptops, phones, or powered hand tools, for example in the construction sector, especially drills, battery-powered drivers, or battery-powered staplers.

[0107] The present invention is further illustrated by the following examples. EXAMPLES

[0108] The average particle size (D50) was determined by dynamic light scattering ("DLS"). Percentages are by weight unless otherwise stated.

[0109] LiOH·OH was purchased from Rockwood Lithium.

[0110] The preparation of the base electrode active material was carried out in a Linn High Term box furnace, Type: VMK-80-S.

[0111] Methanol and toluene were pre-dried according to standard laboratory methods.

[0112] Unless otherwise stated, all synthetic steps were carried out in a glove box (MB200B, MBraun) under an argon atmosphere, with oxygen and water concentrations below 0.1 ppm.

[0113] Al(CH3)3 was used as a 2 M solution in toluene and was purchased from Sigma-Aldrich.

[0114] Si(OC2H5)4 ("Si(OEt)4") was used in bulk and purchased from Merck KGaA.

[0115] I. Preparation of Base Electrode Active Material I.1 Preparation of precursor P-CAM.1 The precipitation of nickel hydroxide was carried out in a continuous stirred tank reactor with a volume of 2.3 liters under nitrogen at 55°C. Aqueous solutions of nickel sulfate, ammonia and sodium hydroxide were fed to the reactor. The respective flow rates were adjusted to obtain a pH value of 12.6 (plus / minus 0.2), a nickel to ammonia molar ratio of 0.8 and a residence time of about 8 hours. The solid obtained was filtered off, washed with deionized water for 12 hours and dried at 120°C for 16 hours. The obtained Ni(OH)2 ("P-CAM.1") had an average particle size D50 of 10 μm.

[0116] I.2 Preparation of base electrode active material B-CAM.1 (LiNiO2) P-CAM.1 (12.981 g, 0.140 mol, 1.00 equiv.) and LiOH HO (5.933 g, 0.141 mol, 1.01 equiv.) were thoroughly mixed, and the resulting mixture was incubated under oxygen flow (5.00 L h -1 , equivalent to approximately 0.65 reactor volume exchanges per hour), 700 °C for 6 h, 3 °C min -1 The calcined product was transferred to a glove box and sieved through a 45 μm metal sieve to give 13.272 g of B-CAM.1. Karl Fischer titration showed a water content below the detection level of 50 ppm.

[0117] I.3 Preparation of precursor P-CAM.2, TM=Ni 0.85 Co 0.10 Mn 0.5 The precipitation reaction was carried out at 55° C. under nitrogen atmosphere in a continuous stirred tank reactor with a volume of 2.3 liters.

[0118] A continuous stirred tank reactor was charged with 1.5 l of the above aqueous solution of (NH4)2SO4. The pH value of the solution was then adjusted to 11.5 using a 25% by weight aqueous solution of sodium hydroxide. An aqueous metal solution containing NiSO4, CoSO4 and MnSO4 (molar ratio 85:10:5, total metal concentration: 1.65 mol / kg), an aqueous sodium hydroxide solution (25% by weight NaOH) and an aqueous ammonia solution (25% by weight ammonia) were simultaneously introduced into the vessel. The molar ratio of ammonia to metal was adjusted to 0.265. The sum of the volumetric flow rates was set to adjust the average residence time to 5 hours. The flow rate of NaOH was adjusted by a pH adjustment circuit to keep the pH value in the vessel at a constant value of 11.58. The apparatus was operated continuously while keeping the liquid level in the vessel constant. The mixed hydroxides of Ni, Co and Mn were collected from the vessel by free overflow. The resulting product slurry contained about 120 g / l of P-CAM.2, a mixed hydroxide of Ni, Co and Mn with an average particle size (D50) of 10.5 μm. P-CAM.2 was removed by filtration, washed with deionized water for 12 hours and dried at 120° C. for 16 hours.

[0119] I.4 B-CAM.2 Manufacturing P-CAM.2 was then mixed with LiOH·H2O in a molar ratio of Li:TM of 1.02:1 and calcined at 780 °C in a pure oxygen stream with a residence time of 10 h. The heating rate was 3 °C / min. Particulate B-CAM.2 was obtained and sieved with a mesh size of 32 μm. Karl Fischer titration showed a water content below the detection level of 50 ppm.

[0120] I.5 Preparation of water-containing electrode active material I.5.1 Production of Moist B-CAM.1, step (a.1) A quantity of 3.5 g of B-CAM.1 was slurried with 15 μl of deionized water in 5 ml of pre-dried methanol and shaken for 5 min. The supernatant liquid phase was removed with a syringe, and the wet B-CAM.1 was then incubated on a Schlenk line at room temperature and 1·10 -3 It was dried for 2 hours at millibar pressure. Wetting was confirmed by Karl Fischer titration, which showed a water content of 1,150 ppm.

[0121] II. Synthesis of the Cathode Active Material of the Present Invention II.1 Synthesis of the cathode active material of the present invention based on B-CAM.1 General Procedure Step (b.1): 7 mL of pre-dried toluene was placed in an oven-dried Schlenk flask equipped with a magnetic stir bar. A combination of Al(CH3)3 and Si(OC2H5)4 in toluene was then added according to Table 1. 2.5 g of water-containing B-CAM.1 was then added. The resulting slurry was allowed to react for 2 h at room temperature while stirring, after which the Schlenk flask was transferred to a Schlenk line equipped with a cold trap between the line and the flask, in which the solvent and excess reagents were removed in vacuum. Once no liquid phase was visible, the flask was attached directly to the Schlenk line and the resulting material was stirred at room temperature and 1·10 -3 It was dried at mbar pressure for 15 hours.

[0122] Step (c.1): The material obtained in step (b.1) is heated in a tube furnace (P330, Nabertherm) under oxygen flow (1.00 l h -1 , equivalent to an exchange of 1.5 reactor volumes per hour) and annealed at 300° C. for 1 hour. The heating and cooling rates were 2.3° C. / min. CAM.1.1 was obtained.

[0123] Step (b.2) is essentially the same as step (b.1), except that moist B-CAM.2 was used as the starting material instead of moist B-CAM.1. CAM.2.1 was obtained.

[0124] [Table 1]

[0125] [Table 2]

[0126] The cathode slurries required for the preparation of the cathodes were prepared by mixing a 7.5 wt.% binder solution of polyvinylidene difluoride (PVDF, Solef 5130, Solvay) in N-methyl-2-pyrrolidone (NMP, ≥ 99.5%, Merck KGaA) with conductive carbon black (Super C65, TIMCAL Ltd.) and NMP in a planetary centrifugal mixer (ARE-250, Thinky) first at 2000 rpm for 3 min and then at 400 rpm for 3 min. After the first mixing, the respective CAM was added to the slurry. For the cathode active material based on B-CAM.1, a sealable screw-cap mixing cup was used and the respective cathode active material was added inside the glove box. For the cathode active material based on B-CAM.2, an open mixing cup was used. The mixture was then stirred again at 2000 rpm for 3 min and 400 rpm for 3 min to obtain a homogenous deep black slurry. Using a motorized film applicator (Erichsen Coatmaster 510), the slurries were directly coated onto 0.03 mm thick aluminum foil using a blade film applicator with a slit height of 120 μm for CAM.2.1 or B-CAM.2, and 140 μm for CAM.1.1 or C-CAM.1, to obtain a coating thickness of ∼10 mg. CAM ·cm -2 The resulting tape was dried in vacuum at 120 °C for 12 h and then calcined with a laboratory calender (Sumet Messtechnik) at a loading of 15 N mm -1 The mixture was calendered between two steel rolls under a line pressure of 1000 psi.

[0127] III.2 Pouch cell manufacturing 50-30mm 2 of microporous polypropylene separator (Celgard 2500), 500 μL of electrolyte consisting of 1.0 M LiPF6 in a 3:7 EC:DEC mass ratio and 2% vinylene carbonate additive, and 42 22 mm 2 A single layer pouch cell was assembled in a dry room (dew point <-55°C) using a graphite anode.

[0128] Test Protocol: In general, in every experiment, at least three cells were successfully cycled and the results were expressed as the average of these cells. They were cycled at 25°C (materials based on B-CAM.1) or 45°C (materials based on B-CAM.2) using a battery test system (Series 4000, MACCOR). The first two cycles were constant current charged to 4.2 V at a rate of 0.1 C, 1 C = 195 mA g for B-CAM.2 and CAM.2.1. -1 , 225mA·g for B-CAM.1 and CAM.1.1 -1 After reaching the voltage limit, charging continued for 1 hour or until the current dropped below 0.02C, depending on which condition was met first. After a 5-minute rest, the cells were discharged at a rate of 0.1C to 2.8V, followed by a 5-minute rest. After these initial cycles, the charge rate was set to 0.5C. The discharge rate was 1C for 10 cycles, followed by rate tests at 0.5C, 1C, 2C, and 3C for 2 cycles each. For extended cycling, the rate tests were repeated after 100 cycles at 1C each.

[0129] [Table 3]

Claims

1. The following steps: (a) Providing an electrode active material represented by the general formula Li １＋ｘ TM １－ｘ O ２ wherein TM is a combination of metals represented by formula (I), x ranges from 0 to 0.2, and the water content ranges from 500 to 1500 ppm, (Ni a Co b Mn c ) 1-d M d (I) (wherein a ranges from 0.3 to 0.4, b ranges from 0 to 0.1, c ranges from 0.6 to 0.7, d ranges from 0 to 0.1, M is Al or Ti or Zr or Mg, and a + b + c = 1) step, and (b) Reacting the electrode active material with a silicon alkoxide and an alkylaluminum compound in one or more sub-steps, and (c) Heat-treating the material thus obtained at a temperature in the range of 100 to 400 °C for 10 minutes to 4 hours in an oxygen-containing atmosphere A method for manufacturing a coated cathode active material, comprising.

2. The method according to claim 1, wherein the silicon alkoxide is selected from tetramethoxysilane and tetraethoxysilane.

3. The method according to claim 1 or 2, wherein the alkyl metal compound in step (b) is selected from trimethylaluminum and triethylaluminum.

4. The method according to claim 1 or 2, wherein the molar ratio of silicon to aluminum in step (b) ranges from 1:10 to 10:

1.

5. The method according to claim 1 or 2, wherein step (b) is carried out in the presence of at least one organic solvent.

6. The method according to claim 1 or 2, wherein in step (b), or in a sub-step before or after step (b), a carbonyl compound or an organometallic compound of cobalt is applied to the electrode active material provided in step (a) or obtained from step (b).

7. A particulate cathode active material containing a core material represented by the general formula Li １＋ｘ TM １－ｘ O ２ wherein TM is a combination of metals represented by formula (I), x ranges from 0 to 0.2, and the outer surface of the core material is heterogeneously coated with a mixed oxide of aluminum and silicon having a uniform composition. (Ni a Co b Mn c ) 1-d M d (I) (wherein a ranges from 0.3 to 0.4, b ranges from 0 to 0.1, c ranges from 0.6 to 0.7, d ranges from 0 to 0.1, M is Al or Ti or Zr or Mg, and a + b + c = 1), a particulate material.

8. The particulate material according to claim 7, wherein the coating comprises a compound selected from LiAlSiO ４ and LiAlSi ２ O ６ , and a compound selected from Li ４ SiO ４ , Li ２ SiO ３ and Li ２ Si ３ O ７ .

9. The particulate material according to claim 7 or 8, wherein the molar ratio of silicon to aluminum ranges from 1:20 to 1:

1.

10. (A) At least one particulate material according to claim 7 or 8, (B) carbon in a conductive state, and (C) a binder polymer A cathode comprising.