WO2020109360A1 - Process for making a partially coated electrode active material - Google Patents

Process for making a partially coated electrode active material Download PDF

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Publication number
WO2020109360A1
WO2020109360A1 PCT/EP2019/082678 EP2019082678W WO2020109360A1 WO 2020109360 A1 WO2020109360 A1 WO 2020109360A1 EP 2019082678 W EP2019082678 W EP 2019082678W WO 2020109360 A1 WO2020109360 A1 WO 2020109360A1
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range
electrode active
active material
zero
process according
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PCT/EP2019/082678
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French (fr)
Inventor
Christoph ERK
Heino Sommer
Ingo Krossing
Arthur MARTENS
Christoph BOLLI
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Basf Se
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Publication of WO2020109360A1 publication Critical patent/WO2020109360A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/04—Processes of manufacture in general
    • H01M4/049—Manufacturing of an active layer by chemical means
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H01M4/1391—Processes of manufacture of electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present invention is directed towards a process for making a partially coated electrode ac tive material wherein said process comprises the following steps:
  • TM is Ni and at least one of Co and Mn, and, optionally, at least one element selected from Al, Mg, Ba, B, and transition metals other than Ni, Co, and Mn, and x is in the range of from -0.05 to 0.2,
  • step (c) treating the material obtained from step (b) with an oxidizing agent
  • step (d) treating the material obtained from step (b) with HF
  • step (e) treating the material obtained from step (b) with a phosphorus-bearing reagent selected from H 3 PO 4 , fluorophosphoric acid and difluorophosphoric acid.
  • a phosphorus-bearing reagent selected from H 3 PO 4 , fluorophosphoric acid and difluorophosphoric acid.
  • the present invention is directed towards a partially coated electrode active material.
  • Lithium ion secondary batteries are modern devices for storing energy. Many application fields have been and are contemplated, from small devices such as mobile phones and laptop com puters through car batteries and other batteries for e-mobility. Various components of the batter ies have a decisive role with respect to the performance of the battery such as the electrolyte, the electrode materials, and the separator. Particular attention has been paid to the cathode materials. Several materials have been suggested, such as lithium iron phosphates, lithium co balt oxides, and lithium nickel cobalt manganese oxides. Although extensive research has been performed the solutions found so far still leave room for improvement.
  • Ni-rich electrode active materials for example electrode active materials that contain at least 50 mole-% or even 75 mole-% or more of Ni, referring to the total metal content, metal referring to metals other than lithium.
  • Ni-rich electrode active materials with excellent electrochemical properties. It was also an objective to provide Ni-rich electrode active materials with excellent electrochemical properties.
  • the inventive process comprises the following steps:
  • step (c) treating the material obtained from step (b) with an oxidizing agent
  • step (d) treating the material obtained from step (b) with HF, and
  • step (e) treating the material obtained from step (b) with a phosphorus-bearing reagent selected from H 3 PO 4 , fluorophosphoric acid and difluorophosphoric acid.
  • a phosphorus-bearing reagent selected from H 3 PO 4 , fluorophosphoric acid and difluorophosphoric acid.
  • the inventive process comprises two steps, steps (a) and (b), and one step selected from steps (c), (d) and (e), in the context of the present invention also referred to as step (a) step (b) and step (c) etc., respectively.
  • step (a) step (b) and step (c) etc. respectively.
  • commencement of steps (b) and (c) is subsequently.
  • the inventive process starts off from an electrode active material according to general formula Lii +x TMi-x0 2 , step (a), wherein TM comprises Ni and at least one of Co and Mn, and, optionally, at least one element selected from Al, Ba, B, and Mg, and x is in the range of from -0.05 to 0.2.
  • Said material is hereinafter also referred to as starting material.
  • at least 50 mole-% of TM is Ni, more preferably at least 75 mole-%.
  • the starting material has an average particle diameter (D50) in the range of from 3 to 20 pm, preferably from 5 to 16 pm.
  • the average particle diameter can be determined, e. g., by light scattering or LASER diffraction or electroacoustic spectroscopy.
  • the particles are usually composed of agglomerates from primary particles, and the above particle diameter refers to the secondary particle diameter.
  • the starting material has a specific surface (BET), hereinafter also referred to as“BET surface”, in the range of from 0.1 to 7.0 m 2 /g.
  • BET surface may be determined by nitrogen adsorption after outgassing of the sample at 200°C for 30 minutes or more and beyond this accordance with DIN ISO 9277:2010.
  • the particulate material provided in step (a) has a moisture content in the range of from 20 to 2,000 ppm, determined by Karl-Fischer titration, preferred are 200 to 1 ,200 ppm.
  • variable TM corresponds to general formula (I a)
  • d being in the range of from zero to 0.1 , preferably from zero to 0.04,
  • M 1 is at least one of Al, Mg, W, Mo, Ti or Zr, preferably at least one of Al, Ti and W.
  • variable c is zero, M 1 is Al and d is in the range of from 0.01 to 0.05.
  • variable TM corresponds to general formula (I b)
  • M 2 is at least one of W, Mo, Ti or Zr.
  • variable TM corresponds to general formula (I c)
  • M 3 is at least one of W, Nb, Mo, Ti or Zr.
  • variable x is preferably in the range of from -0.05 to 0.2.
  • TM corresponds to general formula (I a) and x is in the range from zero to 0.2, preferably from zero to 0.1 and even more preferably 0.01 to 0.05. In one embodiment of the present invention TM corresponds to general formula (I b) and x is in the range of from -0.05 to zero.
  • TM is selected from Nio.6Coo.2Mno.2, Ni07Co02Mn0.-i, Nio.sCoo.i Mno.i, Ni085Co0.1 Mn0.05, Ni0.89Co0055AI0.055, and Ni0.91Co0045AI0.045. In another specific embodiment, TM is selected from Ni02Co005Mn075.
  • the electrode active material provided in step (a) is usually free from conductive carbon, that means that the conductive carbon content of starting material is less than 1 % by weight, referring to said starting material, preferably 0.001 to 1.0 % by weight.
  • traces of ubiquitous metals such as sodium, calcium, iron or zinc as impurities will not be taken into account in the de scription of the present invention. Traces in this context will mean amounts of 0.05 mol-% or less, referring to the total metal content of the starting material.
  • the electrode active material provided in step (a) is used without further preparatory steps.
  • a preparatory step (p) is performed before subjecting said electrode active material to step (b).
  • said particulate material is treated with an aqueous medium.
  • Said aqueous medium may have a pH value in the range of from 2 up to 14, preferably at least 5, more preferably from 7 to 12.5 and even more preferably from 8 to 12.5.
  • the pH value is measured at the beginning of step (p). It is observed that in the course of step (p), the pH value raises to at least 10.
  • the water hardness of aqueous medium and in particular of the water used for step (p) is at least partially removed, especially calcium.
  • the use of desalinized water is preferred.
  • step (p) is performed by slurrying the particulate material from calcination in water followed by removal of the water by a solid-liquid separation method and drying at a maximum temperature in the range of from 50 to 450°C.
  • the aqueous medium used in step (p) may contain ammonia or at least one transition metal salt, for example a nickel salt or a cobalt salt.
  • transition metal salts preferably bear counterions that are not detrimental to an electrode active material. Sulfate and nitrate are feasible. Chloride is not preferred.
  • step (p) is performed at a temperature in the range of from 5 to 85°C, preferred are 10 to 60°C.
  • step (p) is performed at normal pressure. It is preferred, though, to perform step (p) under elevated pressure, for example at 10 mbar to 10 bar above normal pressure, or with suction, for example 50 to 250 mbar below normal pressure, preferably 100 to 200 mbar below normal pressure.
  • Step (p) may be performed, for example, in a vessel that can be easily discharged, for example due to its location above a filter device.
  • a vessel may be charged with starting material followed by introduction of aqueous medium.
  • such vessel is charged with aqueous medium followed by introduction of starting material.
  • starting material and aqueous medium are introduced simultaneously.
  • the volume ratio of starting material and total aqueous medium in step (p) is in the range of from 2:1 to 1 :5, preferably from 2:1 to 1 :2.
  • Step (p) may be supported by mixing operations, for example shaking or in particular by stirring or shearing, see below.
  • step (p) has a duration in the range of from 1 minute to 30 minutes, preferably 1 minute to less than 5 minutes. A duration of 5 minutes or more is possible in embodiments wherein in step (p), water treatment and water removal are performed overlapping or simultaneously.
  • step (p) water treatment and water removal are performed consecutively.
  • water may be removed by any type of filtration, for example on a band filter or in a filter press.
  • Water removal includes removing said aqueous medium from treated particulate material by way of a solid-liquid separation, for example by decanting or preferably by filtration.
  • the slurry obtained in step (p) is discharged directly into a centrifuge, for example a decanter centrifuge or a filter centrifuge, or on a filter device, for example a suction filter or in a belt filter that is located preferably directly below the vessel in which step (p) is performed. Then, filtration is commenced.
  • a centrifuge for example a decanter centrifuge or a filter centrifuge
  • a filter device for example a suction filter or in a belt filter that is located preferably directly below the vessel in which step (p) is performed.
  • step (p) is performed in a filter device with stirrer, for example a pressure filter with stirrer or a suction filter with stirrer. At most 3 minutes after - or even immediately after - having combined starting material and aqueous medium in accordance with step (p), removal of aqueous medium is commenced by starting the filtration.
  • steps (p) may be performed on a Bijchner funnel, and step (p) may be supported by manual stirring.
  • step (p) is performed in a filter device, for example a stirred filter device that allows stirring of the slurry in the filter or of the filter cake.
  • a filter device for example a stirred filter device that allows stirring of the slurry in the filter or of the filter cake.
  • the water removal has a duration in the range of from 1 minute to 1 hour.
  • stirring in step (p) is performed with a rate in the range of from 1 to 50 rounds per minute (“rpm”), preferred are 5 to 20 rpm.
  • filter media may be selected from ceramics, sintered glass, sintered metals, organic polymer films, non-wovens, and fabrics.
  • step (p) is carried out under an atmosphere with reduced CO2 content, e.g., a carbon dioxide content in the range of from 0.01 to 500 ppm by weight, preferred are 0.1 to 50 ppm by weight.
  • the CO2 content may be determined by, e.g., optical methods using infrared light. It is even more preferred to perform step (p) under an atmosphere with a carbon dioxide content below detection limit for example with infrared-light based optical methods.
  • the water-treated material is dried, for example at a temperature in the range of from 40 to 250°C at a normal pressure or reduced pressure, for example 1 to 500 mbar. If drying under a lower temperature such as 40 to 100°C is desired a strongly reduced pressure such as from 1 to 20 mbar is preferred.
  • said drying is carried out under an atmosphere with reduced CO2 content, e.g., a carbon dioxide content in the range of from 0.01 to 500 ppm by weight, preferred are 0.1 to 50 ppm by weight.
  • the CO2 content may be determined by, e.g., optical methods using infrared light. It is even more preferred to perform step (d) under an atmosphere with a carbon dioxide content below detection limit for example with infrared-light based optical methods.
  • said drying has a duration in the range of from 1 to 10 hours, preferably 90 minutes to 6 hours.
  • step (b) said electrode active material is treated with a compound according to the general formula (h AI-OR 1 ⁇ wherein R 1 is selected from branched C3-C4-alkyl, for example iso-propyl, iso-butyl, sec. -butyl and tert.-butyl.
  • R 1 is selected from branched C3-C4-alkyl, for example iso-propyl, iso-butyl, sec. -butyl and tert.-butyl.
  • step (b) is carried out at a temperature in the range of from 15 to 300°C, preferably 50 to 200°C, even more preferably 80 to 180°C.
  • step (b) is carried out by mixing electrode active material and compound according to the general formula (H2AI-OR 1 )2 at ambient temperature and then heat ing the mixture to 80 to 200°C.
  • step (b) is carried out in a temperature profile, preferably under ramping up the temperature, for example first to 50 to 80°C and then to 150 to 250°C.
  • step (b) is carried out in a temperature profile, preferably under ramping up the temperature, for example first to 150 to 180°C and then to 200 to 250°C.
  • electrode active material according to step (a) is mixed with a compound according to the general formula (H2AI-OR 1 )2, and then allowed to react.
  • the treatment according to step (b) is performed by exposing the electrode active material from step (a) to an atmosphere containing (H2AI-OR 1 )2.
  • said atmosphere in step (b) is an atmosphere of dry noble gas or dry nitrogen.
  • “dry” refers to a water content of less than 10 ppm, for example 3 to 5 ppm.
  • step (b) is carried out in vacuo, for example under a pressure in the range of from 0.1 to 10 mbar.
  • the duration of step (b) is in the range of from 1 minute to 24 hours, preferably 30 minutes to 12 hours.
  • the amount of (H2AI-OR 1 )2 is selected in a way that a monomolecular lay of Al compounds may be deposited on the electrode active material pro- vided in step (a).
  • the amount of (H2AI-OR 1 )2 is in the range of from 0.01 to 10% by weight, referring to electrode active material provided in step (a), preferred are 0.05 to 7.5%.
  • a significantly higher amount of (H2AI-OR 1 )2 may lead to decomposition of (H2AI-OR 1 )2 apart from the surface of electrode active material provided in step (a) and thus to formation of free aluminium oxide.
  • compound (H2AI-OR 1 )2 is evaporated, for example sublimed, and a forced flow of gas brings (H2AI-OR 1 )2 into contact with electrode active material provided in step (a).
  • step (a)2 By the above treatment with (H2AI-OR 1 )2, it may be observed that the specific surface of the electrode active material provided in step (a) is increased, for example to 1 to 10 m 2 /g.
  • Step (b) may be carried out in a stirred tank reactor, in a tubular reactor, or in a micro-wave heated reactor.
  • step (b) is performed in a tub ular reactor in which a freshly-manufactured electrode active material is cooled down after cal cination.
  • step (b) is carried out in the absence of a solvent.
  • Step (b) is followed by an after-treatment step, selected from
  • step (c) treating the material obtained from step (b) with an oxidizing agent, or
  • step (d) treating the material obtained from step (b) with HF, or
  • step (e) optionally, treating the material obtained from step (b) with a phosphorus-bearing reagent selected from H 3 PO 4 , fluorophosphoric acid and difluorophosphoric acid.
  • a phosphorus-bearing reagent selected from H 3 PO 4 , fluorophosphoric acid and difluorophosphoric acid.
  • Said after-treatment step is useful to remove residual Al-H moieties remaining after step (b).
  • Al- H groups are highly reactive and may lead to decomposition of an electrolyte.
  • the oxidizing agent in step (c) is selected from oxygen, and step (c) is performed by exposing the material treated according to step (b) with air, air/nitrogen mixtures or oxygen-enriched air. Dry air is preferred.
  • step (c) is performed at a temperature in the range of from zero to 100°C, preferably from 20 to 80°C. In one embodiment of the present invention, step (c) is performed at a pressure in the range of from ambient pressure to 10 bar, preferably at least 5 mbar above ambient pressure up to 5 bar. In one embodiment of the present invention, step (c) has a duration in the range of from 10 minutes up to 72 hours, preferred from 1 to 3 hours.
  • step (c) is carried out with an excess of oxygen referring to Al in step (b).
  • step (d) is performed by exposing the material treated according to step (b) with gaseous HF, either pure or diluted with an inert gas such as, but not limited to dry nitrogen or rare gases like dry argon, preferably with dry nitrogen.
  • gaseous HF either pure or diluted with an inert gas such as, but not limited to dry nitrogen or rare gases like dry argon, preferably with dry nitrogen.
  • HF is preferred over HF sources like NH4F-HF and NH4F.
  • step (d) is performed at a temperature in the range of from zero to 100°C, preferably from 20 to 50°C.
  • step (d) is performed at a pressure in the range of from ambient pressure to 10 bar, preferably at least 5 mbar above ambient pressure up to 5 bar.
  • step (d) has a duration in the range of from 10 minutes up to 5 hours, preferred from 1 to 3 hours.
  • step (e) is performed by treating the material ob tained after step (b) with a solution of H3PO4, fluorophosphoric acid or difluorophosphoric acid in an organic solvent, for example dimethyl carbonate.
  • step (d) is performed at a temperature in the range of from zero to 100°C, preferably from 20 to 50°C.
  • step (e) has a duration in the range of from 10 minutes up to 5 hours, preferred from 1 to 3 hours.
  • the amount of HF added in step (d) is calculated to a molar ratio in the range of from 1.5 : 1.0 to 2.5 : 1.0, referring to Al from (H2AI-OR 1 )2 employed instep (b), preferred are 1.9 : 1.0 to 2.1 : 1.0.
  • the specific surface (BET) of electrode active material is slightly decreased compared to step (b), for example to a range of from 0.45 to 8 m 2 /g, preferably 0.5 to 7.5 m 2 /g.
  • Such purging steps may be performed with nitrogen or rare gases, preferably nitrogen. Suitable temperatures for purging steps are 10 to 100°C. Suitable duration of such - optional - purging step is 10 seconds to 30 minutes.
  • treated electrode active materials are obtained that exhibit excellent electrochemical properties when used in lithium-ion batteries.
  • Said treated electrode active materials contain certain amount of finely divided Al(0) embedded in aluminium oxide species such as alumina or lithium aluminate.
  • a further aspect of the present invention relates to particulate electrode active materials, here inafter also referred to as“inventive electrode active materials” or“electrode active materials according to the (present) invention”.
  • Inventive electrode active materials are based on materials with a general formula Lii +x TMi- x 0 2 , wherein TM is a combination of Ni, Co and, optionally, Mn, and, optionally, at least one element selected from Al, Mg, Ba, B, and transition metals other than Ni, Co, and Mn, and x is in the range of from zero to 0.2, wherein at least 60 mole-% of the transition metal of TM is Ni, wherein the outer surface of said particles is coated with a combination of aluminum oxide species and metallic Al.
  • Aluminium oxide species may be selected from alumina or lithium aluminate and combinations therefrom.
  • inventive electrode active materials are based on materials with a general formula Lii +x TMi- x 0 2 , wherein TM is a combination of Ni and Mn, and, optionally, at least one element selected from Al, Mg, Ba, B, and transition metals other than Ni and Mn, and x is in the range of from zero to 0.2, wherein at least 45 mole-% of the transition metal of TM is Mn, wherein the outer surface of said particles is coated with a combination of aluminum oxide species and metallic Al.
  • Aluminium oxide species may be selected from alumina or lithium aluminate and combinations therefrom.
  • the molar ratio of Al(0) - metallic aluminium - and AI2O3 is in the range from about 1 :1 , for example 1.1 : 1.0 to 1.0 : 1.1.
  • the molar ratio may be estimated, e.g., by solid-state 27 AI NMR spectroscopy.
  • the molar ratio of Al(0) - metallic aluminium - and lithium aluminate, calculated as UAIO2 is in the range from about 1 :2, for example 1 :1 to 2:1.
  • the molar ratio may be estimated by solid-state 27 AI NMR spectroscopy as well.
  • inventive electrode active materials have an average particle diameter (D50) in the range of from 3 to 20 pm, preferably from 5 to 16 pm.
  • the average particle diameter may be determined, e. g., by light scattering or LASER diffraction or electroacoustic spectroscopy.
  • the particles are usually composed of agglomerates from primary particles, and the above particle diameter refers to the secondary particle diameter.
  • inventive electrode active materials have a surface (BET) in the range of from 0.1 to 1 .5 m 2 /g, determined according to DIN-ISO 9277:2003-05, especially those with TM according to formula (I a) or (I b).
  • BET surface
  • inventive electrode active materials have a sur face (BET) in the range of from 2 to 8 m 2 /g, preferably 3 to 7.5 m 2 /g, determined according to DIN-ISO 9277:2003-05, especially those with TM according to formula (I c).
  • BET sur face
  • a further aspect of the present invention refers to electrodes comprising at least one electrode material active according to the present invention. They are particularly useful for lithium ion batteries. Lithium ion batteries comprising at least one electrode according to the present invention exhibit a good discharge behavior. Electrodes comprising at least one electrode active material according to the present invention are hereinafter also referred to as inventive cathodes or cathodes according to the present invention.
  • Cathodes according to the present invention can comprise further components. They can comprise a current collector, such as, but not limited to, an aluminum foil. They can further comprise conductive carbon and a binder.
  • Suitable binders 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, especially 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 additionally suitable. Particular preference is given to polyacrylonitrile.
  • polyacrylonitrile is understood to mean not only polyacrylonitrile homopolymers but also copolymers of acrylonitrile with 1 ,3-butadiene or styrene. Preference is given to polyacrylonitrile homopolymers.
  • polyethylene is not only understood to mean homopolyethylene, but also copolymers of ethylene which comprise at least 50 mol% of copolymerized ethylene and up to 50 mol% of at least one further comonomer, for example a-olefins such as propylene, butylene (1 -butene), 1 -hexene, 1-octene, 1 -decene, 1 -dodecene, 1 -pentene, and also isobutene, vinylaromatics, for example styrene, and also (meth)acrylic acid, vinyl acetate, vinyl propionate, Ci-Cio-alkyl esters of (meth)acrylic acid, especially methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-butyl acrylate, 2-ethylhexyl acrylate, n-butyl me
  • polypropylene is not only understood to mean homopoly propylene, but also copolymers of propylene which comprise at least 50 mol% of copolymerized propylene and up to 50 mol% of at least one further comonomer, for example ethylene and a- olefins such as butylene, 1 -hexene, 1 -octene, 1 -decene, 1 -dodecene and 1 -pentene.
  • Polypropylene is preferably isotactic or essentially isotactic polypropylene.
  • polystyrene is not only understood to mean homopolymers of styrene, but also copolymers with acrylonitrile, 1 ,3-butadiene, (meth)acrylic acid, Ci- Cio-alkyl esters of (meth)acrylic acid, 1 ,2-diphenylethylene, a-methylstyrene, and divinylben- zene, especially 1 ,3-divinylbenzene.
  • Another preferred binder is polybutadiene.
  • Suitable binders are selected from polyethylene oxide (PEO), cellulose, carboxymethyl- cellulose, polyimides and polyvinyl alcohol.
  • binder is selected from those (co)polymers which have an average molecular weight M w in the range from 50,000 to 1 ,000,000 g/mol, preferably to 500,000 g/mol.
  • Binder may be cross-linked or non-cross-linked (co)polymers.
  • binder is selected from halo- genated (co)polymers, especially from fluorinated (co)polymers.
  • Halogenated or fluorinated (co)polymers are understood to mean those (co)polymers which comprise at least one
  • Examples are polyvinyl chloride, polyvinylidene chloride, polytetrafluoroethylene, pol- yvinylidene fluoride (PVdF), tetrafluoroethylene-hexafluoropropylene copolymers, vinylidene fluoride-hexafluoropropylene copolymers (PVdF-HFP), vinylidene fluoride-tetrafluoroethylene copolymers, perfluoroalkyl vinyl ether copolymers, ethylene-tetrafluoroethylene copolymers, vinylidene fluoride-chlorotrifluoroethylene copolymers and ethylene-chlorofluoroethylene copol ymers.
  • PVdF pol- yvinylidene fluoride
  • PVdF-HFP vinylidene fluoride-hexafluoropropylene copolymers
  • PVdF-HFP vinylidene fluoride-tetrafluor
  • Suitable binders are especially polyvinyl alcohol and halogenated (co)polymers, for example polyvinyl chloride or polyvinylidene chloride, especially fluorinated (co)polymers such as polyvi nyl fluoride and especially polyvinylidene fluoride and polytetrafluoroethylene.
  • inventive cathodes may comprise 1 to 15% by weight of binder(s), referring to electrode active material. In other embodiments, inventive cathodes may comprise 0.1 up to less than 1 % by weight of binder(s).
  • a further aspect of the present invention is a battery, containing at least one cathode comprising inventive electrode active material, carbon, and binder, at least one anode, and at least one electrolyte.
  • Said anode may contain at least one anode active material, such as carbon (graphite), PO2, lithium titanium oxide, silicon or tin.
  • Said anode may additionally contain a current collector, for example a metal foil such as a copper foil.
  • Said electrolyte may comprise at least one non-aqueous solvent, at least one electrolyte salt and, optionally, additives.
  • Non-aqueous solvents for electrolytes can be liquid or solid at room temperature and are pref erably selected from among polymers, cyclic or acyclic ethers, cyclic and acyclic acetals and cyclic or acyclic organic carbonates.
  • polyalkylene glycols examples include poly-Ci-C 4 - alkylene glycols and in particular polyethylene glycols.
  • Polyethylene glycols can here comprise up to 20 mol% of one or more Ci-C4-alkylene glycols.
  • Polyalkylene glycols are preferably poly- alkylene glycols having two methyl or ethyl end caps.
  • the molecular weight M w of suitable polyalkylene glycols and in particular suitable polyethylene glycols can be at least 400 g/mol.
  • the molecular weight M w of suitable polyalkylene glycols and in particular suitable polyethylene glycols can be up to 5 000 000 g/mol, preferably up to 2 000 000 g/mol.
  • Suitable acyclic ethers are, for example, diisopropyl ether, di-n-butyl ether,
  • Suitable cyclic ethers are tetrahydrofuran and 1 ,4-dioxane.
  • Suitable acyclic acetals are, for example, dimethoxymethane, diethoxymethane,
  • Suitable cyclic acetals are 1 ,3-dioxane and in particular 1 ,3-dioxolane.
  • Suitable acyclic organic carbonates are dimethyl carbonate, ethyl methyl carbonate and diethyl carbonate.
  • Suitable cyclic organic carbonates are compounds according to the general formu lae (II) and (III)
  • R 2 , R 3 and R 4 can be identical or different and are selected from among hydrogen and Ci-C4-alkyl, for example methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl and tert- butyl, with R 4 and R 3 preferably not both being tert-butyl.
  • R 2 is methyl and R 3 and R 4 are each hydrogen, or R 2 , R 3 and R 4 are each hydrogen.
  • Another preferred cyclic organic carbonate is vinylene carbonate, formula (IV).
  • the solvent or solvents is/are preferably used in the water-free state, i.e. with a water content in the range from 1 ppm to 0.1% by weight, which can be determined, for example, by Karl-Fischer titration.
  • Electrolyte (C) further comprises at least one electrolyte salt.
  • Suitable electrolyte salts are, in particular, lithium salts.
  • suitable lithium salts are LiPFs, L1BF4, UCIO4, LiAsF 6 , UCF3SO3, LiC(CnF2n + iS0 2 )3, lithium imides such as LiN(C n F2n+iSC>2)2, where n is an integer in the range from 1 to 20, LiN(S0 2 F) 2 , L SiFe, LiSbFe, LiAICU and salts of the general formula (C n F2n+iSC>2)tYLi, where m is defined as follows:
  • Preferred electrolyte salts are selected from among LiC(CF 3 S0 2 )3, LiN(CF 3 S0 2 ) 2 , LiPF 6 , LiBF , UCIO4, with particular preference being given to LiPF 6 and LiN(CF 3 S0 2 ) 2 .
  • batteries according to the invention comprise one or more separators by means of which the electrodes are mechanically separated.
  • Suitable sepa rators are polymer films, in particular porous polymer films, which are unreactive toward metallic lithium.
  • Particularly suitable materials for separators are polyolefins, in particular film-forming porous polyethylene and film-forming porous polypropylene.
  • Separators composed of polyolefin, in particular polyethylene or polypropylene can have a porosity in the range from 35 to 45%. Suitable pore diameters are, for example, in the range from 30 to 500 nm.
  • separators can be selected from among PET nonwovens filled with inorganic particles.
  • Such separators can have porosities in the range from 40 to 55%. Suitable pore diameters are, for example, in the range from 80 to 750 nm.
  • Batteries according to the invention further comprise a housing which can have any shape, for example cuboidal or the shape of a cylindrical disk or a cylindrical can.
  • a metal foil configured as a pouch is used as housing.
  • Batteries according to the invention display a good discharge behavior, for example at low temperatures (zero °C or below, for example down to -10°C or even less), a very good discharge and cycling behavior.
  • Batteries according to the invention can comprise two or more electrochemical cells that com bined with one another, for example can be connected in series or connected in parallel. Connection in series is preferred.
  • at least one of the electrochemical cells contains at least one cathode according to the invention.
  • the majority of the electrochemical cells contains a cathode according to the present invention.
  • all the electrochemical cells contain cathodes according to the present invention.
  • the present invention further provides for the use of batteries according to the invention in appliances, in particular in mobile appliances.
  • mobile appliances are vehicles, for example automobiles, bicycles, aircraft or water vehicles such as boats or ships.
  • Other examples of mobile appliances are those which move manually, for example computers, especially laptops, telephones or electric hand tools, for example in the building sector, especially drills, battery-powered screwdrivers or battery-powered staplers.
  • ICP-OES Inductively coupled plasma optical emission spectrometry
  • a stirred tank reactor was filled with deionized water and 49 g of ammonium sulfate per kg of water.
  • the solution was tempered to 55°C and a pH value of 12 was adjusted by adding an aqueous sodium hydroxide solution.
  • the co-precipitation reaction was started by simultaneously feeding an aqueous transition metal sulfate solution and aqueous sodium hydroxide solution at a flow rate ratio of 1.8, and a total flow rate resulting in a residence time of 8 hours.
  • the transition metal solution contained Ni, Co and Mn at a molar ratio of 8.5:1 .0:0.5 and a total transition metal concentration of 1.65 mol/kg.
  • the aqueous sodium hydroxide solution was a 25 wt.% sodium hydroxide solution and 25 wt.% ammonia solution in a weight ratio of 6.
  • the pH value was kept at 12 by the separate feed of an aqueous sodium hydroxide solution. Beginning with the start-up of all feeds, mother liquor was removed continuously. After 33 hours all feed flows were stopped.
  • the mixed transition metal (TM) oxyhydroxide precursor TM-OH.1 was obtained by filtration of the resulting suspension, washing with distilled water, drying at 120°C in air and sieving.
  • C-CAM.1 The mixed transition metal oxyhydroxide TM-OH.1 was mixed with LiOH monohydrate to obtain a Li/(TM) molar ratio of 1.03. The mixture was heated to 760°C and kept for 10 hours in a forced flow of a mixture of 60% oxygen and 40% nitrogen (by volume). After cooling to ambient temperature the powder was deagglomerated and sieved through a 32 pm mesh to obtain the electrode active material C-CAM 1.
  • D50 9.0 pm determined using the technique of laser diffraction in a Mastersize 3000 instrument from Malvern Instruments. Residual moisture at 250 °C was determined to be 300 ppm.
  • a glass vial was charged with 15 g of C-CAM.1. An amount of 45 mg (H2AI-Of-C4Hg)2 was added (0.3 % by weight). The vial with the mixture so obtained was sealed and then heated to 180°C for 2 hours, then cooled to ambient temperature. Inventive CAM.2 was obtained and analyzed. Al-content of CAM.2: 0.06 % by weight, determined by ICP-OES. I.2.3 Treatment with HF
  • CAM.2 An amount of 15 g of CAM.2 was transferred inside a glove box into a PFA (perfluoroalkoxy- polymer) batch reactor, equipped with a stir bar, and sealed.
  • the reactor was transferred to a Monel vacuum line with a volume of 74 ml_ and evacuated. Then the vacuum line was filled with 2 equiv. of gaseous HF (330 mbar) with respect to the HAIO moieties calculated, passed into the evacuated batch reactor and filled with N2 up to a pressure of 1 atm.
  • the CAM.2 was stirred in this HF/N2 atmosphere for 1 h at ambient temperature. Afterwards the residual HF was pumped off, the reactor was filled with Ar and transferred to the glove box.
  • CAM.3 was ob tained.
  • Electrodes contained 93% CAM.3, 1 .5% carbon black (Super C65, Imerys Graphite & Carbon, Switzerland), 2.5% graphite (SFG6L, Imerys Graphite & Carbon, Switzerland) and 3% binder (polyvinylidene fluoride Sole ⁇ 5130, Solvay). Slurries were mixed in N-methyl-2-pyrrolidone (Sigma Aldrich) and cast onto aluminum foil (15 pm thick) by doctor blading at a 1 10 pm wet thickness. After drying the electrodes overnight at 80 °C in vacuo, circular 13 mm diameter elec trodes were punched, weighed and dried at 120 °C under vacuum over a period of 16 hours before placing it into an argon filled glove box.
  • N-methyl-2-pyrrolidone Sigma Aldrich
  • Coin-type electrochemical cells were assembled in an argon-filled glovebox.
  • the positive 13 mm diameter (loading: 1 1.3+1.1 mg cm -2 ) electrode was separated from the Li foil (0.75 mm thick, Alfa Aesar, United States) by a glass fiber separator (Whatman GF/D). 300 pi of LP47 (1 M LiPF 6 in ethylene carbonate (EC):diethyl carbonate (DEC), 3:7 by weight) was used as the electrolyte.
  • LP47 1 M LiPF 6 in ethylene carbonate (EC):diethyl carbonate (DEC), 3:7 by weight
  • Cells were galvanostatically cycled between 3.0 and 4.3 V at a rate of 210 mA/g for 1 C at 25 °C, using an Astrol (Switzerland) standard battery cycler.

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Abstract

Process for making a partially coated electrode active material wherein said process comprises the following steps: (a) providing an electrode active material according to general formula Li1+xTM1-x02, wherein TM is Ni and at least one of Co and Mn, and, optionally, at least one element selected from Al, Mg, Ba, B, and transition metals other than Ni, Co, and Mn, and x is in the range of from -0.05 to 0.2, (b) treating said electrode active material with a compound according to the general formula (H2AI-OR1 )2 wherein R1 is selected from C2-C6-alkyl, followed by an after-treatment step selected from (c) treating the material obtained from step (b) with an oxidizing agent, (d) treating the material obtained from step (b) with HP, and (e) treating the material obtained from step (b) with a phosphorus-bearing reagent selected from H3PO4, fluorophosphoric acid and difluorophosphoric acid.

Description

Process for making a partially coated electrode active material
The present invention is directed towards a process for making a partially coated electrode ac tive material wherein said process comprises the following steps:
(a) providing an electrode active material according to general formula I_H+CTMI-C02, wherein TM is Ni and at least one of Co and Mn, and, optionally, at least one element selected from Al, Mg, Ba, B, and transition metals other than Ni, Co, and Mn, and x is in the range of from -0.05 to 0.2,
(b) treating said electrode active material with a compound according to the general formula (H2AI-OR1 )2 wherein R1 is selected from iso-propyl, iso-butyl, sec. -butyl and tert. -butyl, fol lowed by an after-treatment step selected from
(c) treating the material obtained from step (b) with an oxidizing agent, and
(d) treating the material obtained from step (b) with HF,
(e) treating the material obtained from step (b) with a phosphorus-bearing reagent selected from H3PO4, fluorophosphoric acid and difluorophosphoric acid.
In addition, the present invention is directed towards a partially coated electrode active material.
Lithium ion secondary batteries are modern devices for storing energy. Many application fields have been and are contemplated, from small devices such as mobile phones and laptop com puters through car batteries and other batteries for e-mobility. Various components of the batter ies have a decisive role with respect to the performance of the battery such as the electrolyte, the electrode materials, and the separator. Particular attention has been paid to the cathode materials. Several materials have been suggested, such as lithium iron phosphates, lithium co balt oxides, and lithium nickel cobalt manganese oxides. Although extensive research has been performed the solutions found so far still leave room for improvement.
Currently, a certain interest in so-called Ni-rich electrode active materials may be observed, for example electrode active materials that contain at least 50 mole-% or even 75 mole-% or more of Ni, referring to the total metal content, metal referring to metals other than lithium.
One problem of lithium ion batteries - especially of Ni-rich electrode active materials - is at tributed to undesired reactions on the surface of the electrode active materials. Such reactions may be a decomposition of the electrolyte or the solvent or both. It has thus been tried to protect the surface without hindering the lithium exchange during charging and discharging. Examples are attempts to coat the electrode active materials with, e.g., aluminium oxide or calcium oxide, see, e.g., US 8,993,051. Other theories assign undesired reactions to free LiOH or U2CO3 on the surface. Attempts have been made to remove such free LiOH or L12CO3 by washing the electrode active material with water, see, e.g., JP 4,789,066 B, JP 5,139,024 B, and US2015/0372300. However, in some instances it was observed that the properties of the resultant electrode active materials did not improve.
It was an objective of the present invention to provide a process for making electrode active materials, in particular Ni-rich electrode active materials with excellent electrochemical properties. It was also an objective to provide Ni-rich electrode active materials with excellent electrochemical properties.
Accordingly, the process defined at the outset has been found, hereinafter also referred to as “inventive process”.
The inventive process comprises the following steps:
(a) providing an electrode active material according to general formula Lii+xTMi-x02, wherein TM is Ni and at least one of Co and Mn, and, optionally, at least one element selected from Al, Mg, Ba, B and transition metals other than Ni, Co, and Mn, and x is in the range of from zero to 0.2,
(b) treating said electrode active material with a compound according to the general formula (H2AI-OR1 )2 wherein R1 is selected from iso-propyl, iso-butyl, sec. -butyl and tert.-butyl, followed by an after-treatment step selected from
(c) treating the material obtained from step (b) with an oxidizing agent,
(d) treating the material obtained from step (b) with HF, and
(e) treating the material obtained from step (b) with a phosphorus-bearing reagent selected from H3PO4, fluorophosphoric acid and difluorophosphoric acid.
The inventive process is described in more detail below.
The inventive process comprises two steps, steps (a) and (b), and one step selected from steps (c), (d) and (e), in the context of the present invention also referred to as step (a) step (b) and step (c) etc., respectively. The commencement of steps (b) and (c) is subsequently.
The inventive process starts off from an electrode active material according to general formula Lii+xTMi-x02, step (a), wherein TM comprises Ni and at least one of Co and Mn, and, optionally, at least one element selected from Al, Ba, B, and Mg, and x is in the range of from -0.05 to 0.2. Said material is hereinafter also referred to as starting material. Preferably, at least 50 mole-% of TM is Ni, more preferably at least 75 mole-%. In one embodiment of the present invention the starting material has an average particle diameter (D50) in the range of from 3 to 20 pm, preferably from 5 to 16 pm. The average particle diameter can be determined, e. g., by light scattering or LASER diffraction or electroacoustic spectroscopy. The particles are usually composed of agglomerates from primary particles, and the above particle diameter refers to the secondary particle diameter.
In one embodiment of the present invention, the starting material has a specific surface (BET), hereinafter also referred to as“BET surface”, in the range of from 0.1 to 7.0 m2/g. The BET surface may be determined by nitrogen adsorption after outgassing of the sample at 200°C for 30 minutes or more and beyond this accordance with DIN ISO 9277:2010.
In one embodiment of the present invention, the particulate material provided in step (a) has a moisture content in the range of from 20 to 2,000 ppm, determined by Karl-Fischer titration, preferred are 200 to 1 ,200 ppm.
In one embodiment of the present invention, the variable TM corresponds to general formula (I a)
(NiaCobMnc)i-dM1d (I a) with a + b + c = 1 and a being in the range of from 0.6 to 0.99, preferably from 0.75 to 0.95, more preferably from 0.85 to 0.95, b being in the range of from 0.01 to 0.2, preferably from 0.025 to 0.2, more preferably from 0.025 to 0.1 , c being in the range of from zero to 0.2, preferably from 0.025 to 0.2, more preferably 0.05 to
0.1 , d being in the range of from zero to 0.1 , preferably from zero to 0.04,
M1 is at least one of Al, Mg, W, Mo, Ti or Zr, preferably at least one of Al, Ti and W.
In one embodiment of the present invention, the variable c is zero, M1 is Al and d is in the range of from 0.01 to 0.05. In another embodiment of the present invention, the variable TM corresponds to general formula (I b)
(Nia*COb*Ale*)l-d*M2d* (I b) with a* + b* + c* = 1 and a* being in the range of from 0.75 to 0.95, preferably from 0.88 to 0.95, b* being in the range of from 0.025 to 0.2, preferably from 0.025 to 0.1 , e* being in the range of from 0.01 to 0.2, preferably from 0.015 to 0.04, d* being in the range of from zero to 0.1 , preferably from zero to 0.02,
M2 is at least one of W, Mo, Ti or Zr.
In another embodiment of the present invention, the variable TM corresponds to general formula (I c)
(Nia**COb**Mn **)i-d*M3d* (I c) with a** + b** + c** = 1 and a** being in the range of from 0.20 to 0.55, b** being in the range of from zero to 0.2, preferably from zero to 0.05, d** being in the range of from 0.4 to 0.75, d* being in the range of from zero to 0.1 , preferably from zero to 0.02,
M3 is at least one of W, Nb, Mo, Ti or Zr.
The variable x is preferably in the range of from -0.05 to 0.2.
In one embodiment of the present invention TM corresponds to general formula (I a) and x is in the range from zero to 0.2, preferably from zero to 0.1 and even more preferably 0.01 to 0.05. In one embodiment of the present invention TM corresponds to general formula (I b) and x is in the range of from -0.05 to zero.
In specific embodiments, TM is selected from Nio.6Coo.2Mno.2, Ni07Co02Mn0.-i, Nio.sCoo.i Mno.i, Ni085Co0.1 Mn0.05, Ni0.89Co0055AI0.055, and Ni0.91Co0045AI0.045. In another specific embodiment, TM is selected from Ni02Co005Mn075.
The electrode active material provided in step (a) is usually free from conductive carbon, that means that the conductive carbon content of starting material is less than 1 % by weight, referring to said starting material, preferably 0.001 to 1.0 % by weight.
Some elements are ubiquitous. In the context of the present invention, traces of ubiquitous metals such as sodium, calcium, iron or zinc as impurities will not be taken into account in the de scription of the present invention. Traces in this context will mean amounts of 0.05 mol-% or less, referring to the total metal content of the starting material.
In one embodiment of the present invention, the electrode active material provided in step (a) is used without further preparatory steps. In another embodiment of the present invention, a preparatory step (p) is performed before subjecting said electrode active material to step (b).
In the optional step (p), said particulate material is treated with an aqueous medium. Said aqueous medium may have a pH value in the range of from 2 up to 14, preferably at least 5, more preferably from 7 to 12.5 and even more preferably from 8 to 12.5. The pH value is measured at the beginning of step (p). It is observed that in the course of step (p), the pH value raises to at least 10.
It is preferred that the water hardness of aqueous medium and in particular of the water used for step (p) is at least partially removed, especially calcium. The use of desalinized water is preferred.
In one embodiment of the present invention, step (p) is performed by slurrying the particulate material from calcination in water followed by removal of the water by a solid-liquid separation method and drying at a maximum temperature in the range of from 50 to 450°C.
In an alternative embodiment of step (p), the aqueous medium used in step (p) may contain ammonia or at least one transition metal salt, for example a nickel salt or a cobalt salt. Such transition metal salts preferably bear counterions that are not detrimental to an electrode active material. Sulfate and nitrate are feasible. Chloride is not preferred.
In one embodiment of the present invention, step (p) is performed at a temperature in the range of from 5 to 85°C, preferred are 10 to 60°C.
In one embodiment of the present invention, step (p) is performed at normal pressure. It is preferred, though, to perform step (p) under elevated pressure, for example at 10 mbar to 10 bar above normal pressure, or with suction, for example 50 to 250 mbar below normal pressure, preferably 100 to 200 mbar below normal pressure.
Step (p) may be performed, for example, in a vessel that can be easily discharged, for example due to its location above a filter device. Such vessel may be charged with starting material followed by introduction of aqueous medium. In another embodiment, such vessel is charged with aqueous medium followed by introduction of starting material. In another embodiment, starting material and aqueous medium are introduced simultaneously.
In one embodiment of the present invention, the volume ratio of starting material and total aqueous medium in step (p) is in the range of from 2:1 to 1 :5, preferably from 2:1 to 1 :2.
Step (p) may be supported by mixing operations, for example shaking or in particular by stirring or shearing, see below.
In one embodiment of the present invention, step (p) has a duration in the range of from 1 minute to 30 minutes, preferably 1 minute to less than 5 minutes. A duration of 5 minutes or more is possible in embodiments wherein in step (p), water treatment and water removal are performed overlapping or simultaneously.
In one embodiment of step (p), water treatment and water removal are performed consecutively. After the treatment with an aqueous medium in accordance to step (p), water may be removed by any type of filtration, for example on a band filter or in a filter press.
In one embodiment of the present invention, at the latest 3 minutes after commencement of step (p), water removal is started. Water removal includes removing said aqueous medium from treated particulate material by way of a solid-liquid separation, for example by decanting or preferably by filtration.
In one embodiment of the present invention, the slurry obtained in step (p) is discharged directly into a centrifuge, for example a decanter centrifuge or a filter centrifuge, or on a filter device, for example a suction filter or in a belt filter that is located preferably directly below the vessel in which step (p) is performed. Then, filtration is commenced.
In a particularly preferred embodiment of the present invention, step (p) is performed in a filter device with stirrer, for example a pressure filter with stirrer or a suction filter with stirrer. At most 3 minutes after - or even immediately after - having combined starting material and aqueous medium in accordance with step (p), removal of aqueous medium is commenced by starting the filtration. On laboratory scale, steps (p) may be performed on a Bijchner funnel, and step (p) may be supported by manual stirring.
In a preferred embodiment, step (p) is performed in a filter device, for example a stirred filter device that allows stirring of the slurry in the filter or of the filter cake. By commencement of the filtration, for example pressure filtration or suction filtration, after a maximum time of 3 minutes after commencement of step (p), water removal is started.
In one embodiment of the present invention, the water removal has a duration in the range of from 1 minute to 1 hour.
In one embodiment of the present invention, stirring in step (p) is performed with a rate in the range of from 1 to 50 rounds per minute (“rpm”), preferred are 5 to 20 rpm.
In one embodiment of the present invention, filter media may be selected from ceramics, sintered glass, sintered metals, organic polymer films, non-wovens, and fabrics.
In one embodiment of the present invention, step (p) is carried out under an atmosphere with reduced CO2 content, e.g., a carbon dioxide content in the range of from 0.01 to 500 ppm by weight, preferred are 0.1 to 50 ppm by weight. The CO2 content may be determined by, e.g., optical methods using infrared light. It is even more preferred to perform step (p) under an atmosphere with a carbon dioxide content below detection limit for example with infrared-light based optical methods.
Subsequently, the water-treated material is dried, for example at a temperature in the range of from 40 to 250°C at a normal pressure or reduced pressure, for example 1 to 500 mbar. If drying under a lower temperature such as 40 to 100°C is desired a strongly reduced pressure such as from 1 to 20 mbar is preferred.
In one embodiment of the present invention, said drying is carried out under an atmosphere with reduced CO2 content, e.g., a carbon dioxide content in the range of from 0.01 to 500 ppm by weight, preferred are 0.1 to 50 ppm by weight. The CO2 content may be determined by, e.g., optical methods using infrared light. It is even more preferred to perform step (d) under an atmosphere with a carbon dioxide content below detection limit for example with infrared-light based optical methods.
In one embodiment of the present invention said drying has a duration in the range of from 1 to 10 hours, preferably 90 minutes to 6 hours.
In step (b), said electrode active material is treated with a compound according to the general formula (h AI-OR1^ wherein R1 is selected from branched C3-C4-alkyl, for example iso-propyl, iso-butyl, sec. -butyl and tert.-butyl.
In one embodiment of the present invention, step (b) is carried out at a temperature in the range of from 15 to 300°C, preferably 50 to 200°C, even more preferably 80 to 180°C. In one embod iment of the present invention, step (b) is carried out by mixing electrode active material and compound according to the general formula (H2AI-OR1 )2 at ambient temperature and then heat ing the mixture to 80 to 200°C. In another embodiment, step (b) is carried out in a temperature profile, preferably under ramping up the temperature, for example first to 50 to 80°C and then to 150 to 250°C. In another embodiment, step (b) is carried out in a temperature profile, preferably under ramping up the temperature, for example first to 150 to 180°C and then to 200 to 250°C.
In one embodiment of the present invention, electrode active material according to step (a) is mixed with a compound according to the general formula (H2AI-OR1)2, and then allowed to react.
In one embodiment of the present invention the treatment according to step (b) is performed by exposing the electrode active material from step (a) to an atmosphere containing (H2AI-OR1)2.
In one embodiment of the present invention, said atmosphere in step (b) is an atmosphere of dry noble gas or dry nitrogen. In the context of the present invention,“dry” refers to a water content of less than 10 ppm, for example 3 to 5 ppm. In another embodiment of the present invention, step (b) is carried out in vacuo, for example under a pressure in the range of from 0.1 to 10 mbar.
In one embodiment of the present invention, the duration of step (b) is in the range of from 1 minute to 24 hours, preferably 30 minutes to 12 hours.
In one embodiment of the present invention, the amount of (H2AI-OR1 )2 is selected in a way that a monomolecular lay of Al compounds may be deposited on the electrode active material pro- vided in step (a). For example, the amount of (H2AI-OR1 )2 is in the range of from 0.01 to 10% by weight, referring to electrode active material provided in step (a), preferred are 0.05 to 7.5%. A significantly higher amount of (H2AI-OR1 )2 may lead to decomposition of (H2AI-OR1 )2 apart from the surface of electrode active material provided in step (a) and thus to formation of free aluminium oxide.
In one embodiment of the present invention, compound (H2AI-OR1 )2 is evaporated, for example sublimed, and a forced flow of gas brings (H2AI-OR1 )2 into contact with electrode active material provided in step (a).
By the above treatment with (H2AI-OR1)2, it may be observed that the specific surface of the electrode active material provided in step (a) is increased, for example to 1 to 10 m2/g.
Step (b) may be carried out in a stirred tank reactor, in a tubular reactor, or in a micro-wave heated reactor. In a special embodiment of the present invention, step (b) is performed in a tub ular reactor in which a freshly-manufactured electrode active material is cooled down after cal cination.
In one embodiment of the present invention, step (b) is carried out in the absence of a solvent.
Step (b) is followed by an after-treatment step, selected from
(c) treating the material obtained from step (b) with an oxidizing agent, or
(d) treating the material obtained from step (b) with HF, or
(e) optionally, treating the material obtained from step (b) with a phosphorus-bearing reagent selected from H3PO4, fluorophosphoric acid and difluorophosphoric acid.
Said after-treatment step is useful to remove residual Al-H moieties remaining after step (b). Al- H groups are highly reactive and may lead to decomposition of an electrolyte.
It is preferred to perform exactly one of the above after-treatment steps, thus, either step (c) or step (d).
In one embodiment of the present invention, the oxidizing agent in step (c) is selected from oxygen, and step (c) is performed by exposing the material treated according to step (b) with air, air/nitrogen mixtures or oxygen-enriched air. Dry air is preferred.
In one embodiment of the present invention, step (c) is performed at a temperature in the range of from zero to 100°C, preferably from 20 to 80°C. In one embodiment of the present invention, step (c) is performed at a pressure in the range of from ambient pressure to 10 bar, preferably at least 5 mbar above ambient pressure up to 5 bar. In one embodiment of the present invention, step (c) has a duration in the range of from 10 minutes up to 72 hours, preferred from 1 to 3 hours.
In one embodiment of the present invention, step (c) is carried out with an excess of oxygen referring to Al in step (b).
In one embodiment of the present invention, step (d) is performed by exposing the material treated according to step (b) with gaseous HF, either pure or diluted with an inert gas such as, but not limited to dry nitrogen or rare gases like dry argon, preferably with dry nitrogen.
Al-H moieties are very reactive towards Bronsted acids. Therefore, HF is preferred over HF sources like NH4F-HF and NH4F.
In one embodiment of the present invention, step (d) is performed at a temperature in the range of from zero to 100°C, preferably from 20 to 50°C.
In one embodiment of the present invention, step (d) is performed at a pressure in the range of from ambient pressure to 10 bar, preferably at least 5 mbar above ambient pressure up to 5 bar.
In one embodiment of the present invention, step (d) has a duration in the range of from 10 minutes up to 5 hours, preferred from 1 to 3 hours.
In one embodiment of the present invention, step (e) is performed by treating the material ob tained after step (b) with a solution of H3PO4, fluorophosphoric acid or difluorophosphoric acid in an organic solvent, for example dimethyl carbonate.
In one embodiment of the present invention, step (d) is performed at a temperature in the range of from zero to 100°C, preferably from 20 to 50°C.
In one embodiment of the present invention, step (e) has a duration in the range of from 10 minutes up to 5 hours, preferred from 1 to 3 hours.
In one embodiment of the present invention, the amount of HF added in step (d) is calculated to a molar ratio in the range of from 1.5 : 1.0 to 2.5 : 1.0, referring to Al from (H2AI-OR1 )2 employed instep (b), preferred are 1.9 : 1.0 to 2.1 : 1.0. By a treatment according to step (d), the specific surface (BET) of electrode active material is slightly decreased compared to step (b), for example to a range of from 0.45 to 8 m2/g, preferably 0.5 to 7.5 m2/g.
In the present invention, additional steps are possible, for example a purging step after step (b) in order to remove unreacted (H2AI-OR1)2, or a purging step after step (d), if applicable. Such purging steps may be performed with nitrogen or rare gases, preferably nitrogen. Suitable temperatures for purging steps are 10 to 100°C. Suitable duration of such - optional - purging step is 10 seconds to 30 minutes.
By the inventive process, treated electrode active materials are obtained that exhibit excellent electrochemical properties when used in lithium-ion batteries. Said treated electrode active materials contain certain amount of finely divided Al(0) embedded in aluminium oxide species such as alumina or lithium aluminate.
A further aspect of the present invention relates to particulate electrode active materials, here inafter also referred to as“inventive electrode active materials” or“electrode active materials according to the (present) invention”. Inventive electrode active materials are based on materials with a general formula Lii+xTMi-x02, wherein TM is a combination of Ni, Co and, optionally, Mn, and, optionally, at least one element selected from Al, Mg, Ba, B, and transition metals other than Ni, Co, and Mn, and x is in the range of from zero to 0.2, wherein at least 60 mole-% of the transition metal of TM is Ni, wherein the outer surface of said particles is coated with a combination of aluminum oxide species and metallic Al. Aluminium oxide species may be selected from alumina or lithium aluminate and combinations therefrom.
In another embodiment, inventive electrode active materials are based on materials with a general formula Lii+xTMi-x02, wherein TM is a combination of Ni and Mn, and, optionally, at least one element selected from Al, Mg, Ba, B, and transition metals other than Ni and Mn, and x is in the range of from zero to 0.2, wherein at least 45 mole-% of the transition metal of TM is Mn, wherein the outer surface of said particles is coated with a combination of aluminum oxide species and metallic Al. Aluminium oxide species may be selected from alumina or lithium aluminate and combinations therefrom.
In one embodiment of the present invention, the molar ratio of Al(0) - metallic aluminium - and AI2O3 is in the range from about 1 :1 , for example 1.1 : 1.0 to 1.0 : 1.1. The molar ratio may be estimated, e.g., by solid-state 27AI NMR spectroscopy. In one embodiment of the present invention, the molar ratio of Al(0) - metallic aluminium - and lithium aluminate, calculated as UAIO2, is in the range from about 1 :2, for example 1 :1 to 2:1. The molar ratio may be estimated by solid-state 27AI NMR spectroscopy as well.
In one embodiment of the present invention, inventive electrode active materials have an average particle diameter (D50) in the range of from 3 to 20 pm, preferably from 5 to 16 pm. The average particle diameter may be determined, e. g., by light scattering or LASER diffraction or electroacoustic spectroscopy. The particles are usually composed of agglomerates from primary particles, and the above particle diameter refers to the secondary particle diameter.
In one embodiment of the present invention inventive electrode active materials have a surface (BET) in the range of from 0.1 to 1 .5 m2/g, determined according to DIN-ISO 9277:2003-05, especially those with TM according to formula (I a) or (I b).
In another embodiment of the present invention inventive electrode active materials have a sur face (BET) in the range of from 2 to 8 m2/g, preferably 3 to 7.5 m2/g, determined according to DIN-ISO 9277:2003-05, especially those with TM according to formula (I c).
A further aspect of the present invention refers to electrodes comprising at least one electrode material active according to the present invention. They are particularly useful for lithium ion batteries. Lithium ion batteries comprising at least one electrode according to the present invention exhibit a good discharge behavior. Electrodes comprising at least one electrode active material according to the present invention are hereinafter also referred to as inventive cathodes or cathodes according to the present invention.
Cathodes according to the present invention can comprise further components. They can comprise a current collector, such as, but not limited to, an aluminum foil. They can further comprise conductive carbon and a binder.
Suitable binders 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, especially 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 additionally suitable. Particular preference is given to polyacrylonitrile. 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. Preference is given to polyacrylonitrile homopolymers.
In the context of the present invention, polyethylene is not only understood to mean homopolyethylene, but also copolymers of ethylene which comprise at least 50 mol% of copolymerized ethylene and up to 50 mol% of at least one further comonomer, for example a-olefins such as propylene, butylene (1 -butene), 1 -hexene, 1-octene, 1 -decene, 1 -dodecene, 1 -pentene, and also isobutene, vinylaromatics, for example styrene, and also (meth)acrylic acid, vinyl acetate, vinyl propionate, Ci-Cio-alkyl esters of (meth)acrylic acid, especially methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-butyl acrylate, 2-ethylhexyl acrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, and also maleic acid, maleic anhydride and itaconic anhydride. Polyethylene may be HDPE or LDPE.
In the context of the present invention, polypropylene is not only understood to mean homopoly propylene, but also copolymers of propylene which comprise at least 50 mol% of copolymerized propylene and up to 50 mol% of at least one further comonomer, for example ethylene and a- olefins such as butylene, 1 -hexene, 1 -octene, 1 -decene, 1 -dodecene and 1 -pentene. Polypropylene is preferably isotactic or essentially isotactic polypropylene.
In the context of the present invention, polystyrene is not only understood to mean homopolymers of styrene, but also copolymers with acrylonitrile, 1 ,3-butadiene, (meth)acrylic acid, Ci- Cio-alkyl esters of (meth)acrylic acid, 1 ,2-diphenylethylene, a-methylstyrene, and divinylben- zene, especially 1 ,3-divinylbenzene.
Another preferred binder is polybutadiene.
Other suitable binders are selected from polyethylene oxide (PEO), cellulose, carboxymethyl- cellulose, polyimides and polyvinyl alcohol.
In one embodiment of the present invention, binder is selected from those (co)polymers which have an average molecular weight Mw in the range from 50,000 to 1 ,000,000 g/mol, preferably to 500,000 g/mol.
Binder may be cross-linked or non-cross-linked (co)polymers.
In a particularly preferred embodiment of the present invention, binder is selected from halo- genated (co)polymers, especially from fluorinated (co)polymers. Halogenated or fluorinated (co)polymers are understood to mean those (co)polymers which comprise at least one
(co)polymerized (co)monomer which has at least one halogen atom or at least one fluorine at om per molecule, more preferably at least two halogen atoms or at least two fluorine atoms per molecule. Examples are polyvinyl chloride, polyvinylidene chloride, polytetrafluoroethylene, pol- yvinylidene fluoride (PVdF), tetrafluoroethylene-hexafluoropropylene copolymers, vinylidene fluoride-hexafluoropropylene copolymers (PVdF-HFP), vinylidene fluoride-tetrafluoroethylene copolymers, perfluoroalkyl vinyl ether copolymers, ethylene-tetrafluoroethylene copolymers, vinylidene fluoride-chlorotrifluoroethylene copolymers and ethylene-chlorofluoroethylene copol ymers.
Suitable binders are especially polyvinyl alcohol and halogenated (co)polymers, for example polyvinyl chloride or polyvinylidene chloride, especially fluorinated (co)polymers such as polyvi nyl fluoride and especially polyvinylidene fluoride and polytetrafluoroethylene.
Inventive cathodes may comprise 1 to 15% by weight of binder(s), referring to electrode active material. In other embodiments, inventive cathodes may comprise 0.1 up to less than 1 % by weight of binder(s).
A further aspect of the present invention is a battery, containing at least one cathode comprising inventive electrode active material, carbon, and binder, at least one anode, and at least one electrolyte.
Embodiments of inventive cathodes have been described above in detail.
Said anode may contain at least one anode active material, such as carbon (graphite), PO2, lithium titanium oxide, silicon or tin. Said anode may additionally contain a current collector, for example a metal foil such as a copper foil.
Said electrolyte may comprise at least one non-aqueous solvent, at least one electrolyte salt and, optionally, additives.
Non-aqueous solvents for electrolytes can be liquid or solid at room temperature and are pref erably selected from among polymers, cyclic or acyclic ethers, cyclic and acyclic acetals and cyclic or acyclic organic carbonates.
Examples of suitable polymers are, in particular, polyalkylene glycols, preferably poly-Ci-C4- alkylene glycols and in particular polyethylene glycols. Polyethylene glycols can here comprise up to 20 mol% of one or more Ci-C4-alkylene glycols. Polyalkylene glycols are preferably poly- alkylene glycols having two methyl or ethyl end caps.
The molecular weight Mw of suitable polyalkylene glycols and in particular suitable polyethylene glycols can be at least 400 g/mol.
The molecular weight Mw of suitable polyalkylene glycols and in particular suitable polyethylene glycols can be up to 5 000 000 g/mol, preferably up to 2 000 000 g/mol.
Examples of suitable acyclic ethers are, for example, diisopropyl ether, di-n-butyl ether,
1 ,2-dimethoxyethane, 1 ,2-diethoxyethane, with preference being given to 1 ,2-dimethoxyethane.
Examples of suitable cyclic ethers are tetrahydrofuran and 1 ,4-dioxane.
Examples of suitable acyclic acetals are, for example, dimethoxymethane, diethoxymethane,
1 ,1-dimethoxyethane and 1 ,1 -diethoxyethane.
Examples of suitable cyclic acetals are 1 ,3-dioxane and in particular 1 ,3-dioxolane.
Examples of suitable acyclic organic carbonates are dimethyl carbonate, ethyl methyl carbonate and diethyl carbonate.
Examples of suitable cyclic organic carbonates are compounds according to the general formu lae (II) and (III)
(II)
(III)
Figure imgf000016_0001
where R2, R3 and R4 can be identical or different and are selected from among hydrogen and Ci-C4-alkyl, for example methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl and tert- butyl, with R4 and R3 preferably not both being tert-butyl.
In particularly preferred embodiments, R2 is methyl and R3 and R4 are each hydrogen, or R2, R3 and R4 are each hydrogen.
Another preferred cyclic organic carbonate is vinylene carbonate, formula (IV).
Figure imgf000017_0001
The solvent or solvents is/are preferably used in the water-free state, i.e. with a water content in the range from 1 ppm to 0.1% by weight, which can be determined, for example, by Karl-Fischer titration.
Electrolyte (C) further comprises at least one electrolyte salt. Suitable electrolyte salts are, in particular, lithium salts. Examples of suitable lithium salts are LiPFs, L1BF4, UCIO4, LiAsF6, UCF3SO3, LiC(CnF2n+iS02)3, lithium imides such as LiN(CnF2n+iSC>2)2, where n is an integer in the range from 1 to 20, LiN(S02F)2, L SiFe, LiSbFe, LiAICU and salts of the general formula (CnF2n+iSC>2)tYLi, where m is defined as follows:
t = 1 , when Y is selected from among oxygen and sulfur,
t = 2, when Y is selected from among nitrogen and phosphorus, and
t = 3, when Y is selected from among carbon and silicon.
Preferred electrolyte salts are selected from among LiC(CF3S02)3, LiN(CF3S02)2, LiPF6, LiBF , UCIO4, with particular preference being given to LiPF6 and LiN(CF3S02)2.
In an embodiment of the present invention, batteries according to the invention comprise one or more separators by means of which the electrodes are mechanically separated. Suitable sepa rators are polymer films, in particular porous polymer films, which are unreactive toward metallic lithium. Particularly suitable materials for separators are polyolefins, in particular film-forming porous polyethylene and film-forming porous polypropylene. Separators composed of polyolefin, in particular polyethylene or polypropylene, can have a porosity in the range from 35 to 45%. Suitable pore diameters are, for example, in the range from 30 to 500 nm.
In another embodiment of the present invention, separators can be selected from among PET nonwovens filled with inorganic particles. Such separators can have porosities in the range from 40 to 55%. Suitable pore diameters are, for example, in the range from 80 to 750 nm.
Batteries according to the invention further comprise a housing which can have any shape, for example cuboidal or the shape of a cylindrical disk or a cylindrical can. In one variant, a metal foil configured as a pouch is used as housing.
Batteries according to the invention display a good discharge behavior, for example at low temperatures (zero °C or below, for example down to -10°C or even less), a very good discharge and cycling behavior.
Batteries according to the invention can comprise two or more electrochemical cells that com bined with one another, for example can be connected in series or connected in parallel. Connection in series is preferred. In batteries according to the present invention, at least one of the electrochemical cells contains at least one cathode according to the invention. Preferably, in electrochemical cells according to the present invention, the majority of the electrochemical cells contains a cathode according to the present invention. Even more preferably, in batteries according to the present invention all the electrochemical cells contain cathodes according to the present invention.
The present invention further provides for the use of batteries according to the invention in appliances, in particular in mobile appliances. Examples of mobile appliances are vehicles, for example automobiles, bicycles, aircraft or water vehicles such as boats or ships. Other examples of mobile appliances are those which move manually, for example computers, especially laptops, telephones or electric hand tools, for example in the building sector, especially drills, battery-powered screwdrivers or battery-powered staplers.
The present invention is further illustrated by the following working examples.
General remarks: unless specifically noted otherwise % refer to percent by weight and ppm refer to ppm by weight.
ICP-OES: Inductively coupled plasma optical emission spectrometry
(H2AI-Of-C4H9)2 was synthesized according to M. Veith et ai, Chem. Ber. 1996, 129, 381 I. Synthesis of starting materials
1.1 Synthesis of a precursor TM-OH.1
A stirred tank reactor was filled with deionized water and 49 g of ammonium sulfate per kg of water. The solution was tempered to 55°C and a pH value of 12 was adjusted by adding an aqueous sodium hydroxide solution.
The co-precipitation reaction was started by simultaneously feeding an aqueous transition metal sulfate solution and aqueous sodium hydroxide solution at a flow rate ratio of 1.8, and a total flow rate resulting in a residence time of 8 hours. The transition metal solution contained Ni, Co and Mn at a molar ratio of 8.5:1 .0:0.5 and a total transition metal concentration of 1.65 mol/kg. The aqueous sodium hydroxide solution was a 25 wt.% sodium hydroxide solution and 25 wt.% ammonia solution in a weight ratio of 6. The pH value was kept at 12 by the separate feed of an aqueous sodium hydroxide solution. Beginning with the start-up of all feeds, mother liquor was removed continuously. After 33 hours all feed flows were stopped. The mixed transition metal (TM) oxyhydroxide precursor TM-OH.1 was obtained by filtration of the resulting suspension, washing with distilled water, drying at 120°C in air and sieving.
1.2 Conversion of TM-OH.1 into an inventive electrode active material
1.2.1 Manufacture of a comparative cathode active material, C-CAM.1 , step (a.1 )
C-CAM.1 : The mixed transition metal oxyhydroxide TM-OH.1 was mixed with LiOH monohydrate to obtain a Li/(TM) molar ratio of 1.03. The mixture was heated to 760°C and kept for 10 hours in a forced flow of a mixture of 60% oxygen and 40% nitrogen (by volume). After cooling to ambient temperature the powder was deagglomerated and sieved through a 32 pm mesh to obtain the electrode active material C-CAM 1.
D50 = 9.0 pm determined using the technique of laser diffraction in a Mastersize 3000 instrument from Malvern Instruments. Residual moisture at 250 °C was determined to be 300 ppm.
1.2.2 Treatment with (H2AI-OR1)2, step (b.1 )
A glass vial was charged with 15 g of C-CAM.1. An amount of 45 mg (H2AI-Of-C4Hg)2 was added (0.3 % by weight). The vial with the mixture so obtained was sealed and then heated to 180°C for 2 hours, then cooled to ambient temperature. Inventive CAM.2 was obtained and analyzed. Al-content of CAM.2: 0.06 % by weight, determined by ICP-OES. I.2.3 Treatment with HF
An amount of 15 g of CAM.2 was transferred inside a glove box into a PFA (perfluoroalkoxy- polymer) batch reactor, equipped with a stir bar, and sealed. The reactor was transferred to a Monel vacuum line with a volume of 74 ml_ and evacuated. Then the vacuum line was filled with 2 equiv. of gaseous HF (330 mbar) with respect to the HAIO moieties calculated, passed into the evacuated batch reactor and filled with N2 up to a pressure of 1 atm. The CAM.2 was stirred in this HF/N2 atmosphere for 1 h at ambient temperature. Afterwards the residual HF was pumped off, the reactor was filled with Ar and transferred to the glove box. CAM.3 was ob tained.
Electrode Preparation:
Electrodes contained 93% CAM.3, 1 .5% carbon black (Super C65, Imerys Graphite & Carbon, Switzerland), 2.5% graphite (SFG6L, Imerys Graphite & Carbon, Switzerland) and 3% binder (polyvinylidene fluoride Sole† 5130, Solvay). Slurries were mixed in N-methyl-2-pyrrolidone (Sigma Aldrich) and cast onto aluminum foil (15 pm thick) by doctor blading at a 1 10 pm wet thickness. After drying the electrodes overnight at 80 °C in vacuo, circular 13 mm diameter elec trodes were punched, weighed and dried at 120 °C under vacuum over a period of 16 hours before placing it into an argon filled glove box.
Half-Cell Electrochemical Measurements:
Coin-type electrochemical cells, were assembled in an argon-filled glovebox. The positive 13 mm diameter (loading: 1 1.3+1.1 mg cm-2) electrode was separated from the Li foil (0.75 mm thick, Alfa Aesar, United States) by a glass fiber separator (Whatman GF/D). 300 pi of LP47 (1 M LiPF6 in ethylene carbonate (EC):diethyl carbonate (DEC), 3:7 by weight) was used as the electrolyte. Cells were galvanostatically cycled between 3.0 and 4.3 V at a rate of 210 mA/g for 1 C at 25 °C, using an Astrol (Switzerland) standard battery cycler.
MAS NMR Measurements:
27 Al and 19F magic angle spinning nuclear magnetic resonance experiments were performed on a Bruker DSX 500 solid-state NMR spectrometer running at a Larmor frequency of 130.34 MHz and 470.65 MHz for 27AI and 19F, respectively. The rotor synchronized Hahn Echo experiments were performed at magic angle spinning rates of 25 kHz to 33.3 kHz using a 2.5 mm MAS probe with an wi /2p frequency of 125 kHz (i.e. a 90° pulse duration of 2 ps). The MAS spectra were detected with relaxation delays of 2 s (27AI) and 20 s (19F). All NMR spectra were meas ured at ambient temperature, leading to sample temperatures of 300 - 325 K, due to frictional heating of the magic angle spinning device.

Claims

Patent Claims
1. Process for making a partially coated electrode active material wherein said process comprises the following steps:
(a) Providing an electrode active material according to general formula Lii+xTMi-x02, wherein TM is Ni and at least one of Co and Mn, and, optionally, at least one element selected from Al, Mg, Ba, B, and transition metals other than Ni, Co, and Mn, and x is in the range of from -0.05 to 0.2,
(b) treating said electrode active material with a compound according to the general formula (FhAI-OR1^ wherein R1 is selected from from iso-propyl, iso-butyl, sec. -butyl and tert.-butyl, followed by an after-treatment step selected from
(c) treating the material obtained from step (b) with an oxidizing agent,
(d) treating the material obtained from step (b) with HF, and
(e) treating the material obtained from step (b) with a phosphorus-bearing reagent se lected from H3PO4, fluorophosphoric acid and difluorophosphoric acid.
2. Process according to claim 1 wherein TM is a combination of metals according to general formula (I a)
(NiaCObMnc)i-dMd (I a) with
a being in the range of from 0.6 to 0.99,
b being in the range of from 0.01 to 0.2,
c being in the range of from zero to 0.2, and
d being in the range of from zero to 0.1 ,
M is at least one of Al, Mg, Ti, Mo, W and Zr, and a + b + c = 1 .
3. Process according to claim 1 wherein TM is a combination of metals according to general formula (I b)
(Nia*COb*Ale*)l-d*M2d* (I b) with a* + b* + c* = 1 and a* being in the range of from 0.75 to 0.95, b* being in the range of from 0.025 to 0.2, e* being in the range of from 0.01 to 0.2, d* being in the range of from zero to 0.1 ,
M2 is at least one of W, Mo, Ti or Zr.
4. Process according to claim 1 wherein TM is a combination of metals according to general formula (I c)
(Nia**COb**Mnd**)i-d*M3d (I c) with a** + b** + c** = 1 and a** being in the range of from 0.20 to 0.55, b** being in the range of from zero to 0.2, d** being in the range of from 0.4 to 0.75, d* being in the range of from zero to 0.1 , preferably from zero to 0.02,
M3 is at least one of W, Nb, Mo, Ti or Zr.
5. Process according to any of the preceding claims wherein the amount of (H2AI-OR1 )2 is in the range of from 0.01 to 10% by weight, referring to electrode active material provided in step (a) .
6. Process according to any of the preceding claims wherein at least 50 mole-% of the metal of TM is Ni.
7. Process according to any of the preceding claims wherein M is Al.
8. Process according to any of the preceding claims wherein the treatment according to step (b) is performed by exposing the electrode active material from step (a) to an atmosphere containing (H2AI-OR1)2.
9. Process according to any of the preceding claims wherein step (c) is performed by exposing material obtained from step (b) to air or oxygen-enriched air.
10. Process according to any of the preceding claims wherein step (d) is performed by exposing material obtained from step (b) to an atmosphere containing HF.
1 1. Process according to any of the preceding claims wherein TM is selected from
Nio.6Coo.2Mno 2, Nio.7Coo.2Mno.i , Nio.sCoo -i Mno.-i , Ni0.85Co0.1 Mn0.05, Ni089Co0.055AI0.055, and N io.91 Co0.045AI0.045·
12. Process according to any of the preceding claims wherein the stoichiometry of Al from step (b) and fluoride in step (d) is in the range of from 2:1 to 1 :2.
13. Particulate electrode active material according to general formula UI+XTMI-X02, wherein TM is a combination of Ni, Co and, optionally, Mn, and, optionally, at least one element selected from Al, Mg, Ba, B, and transition metals other than Ni, Co, and Mn, and x is in the range of from zero to 0.2, wherein at least 60 mole-% of the transition metal of TM is Ni, wherein the outer surface of said particles is coated with a combination of aluminum oxide species and metallic Al.
14. Particulate electrode active material according to general formula Lii+xTMi-x02, wherein TM is a combination of Ni and Mn, and, optionally, at least one element selected from Al, Mg, Ba, B, and transition metals other than Ni and Mn, and x is in the range of from zero to 0.2, wherein at least 45 mole-% of the transition metal of TM is Mn, wherein the outer surface of said particles is coated with a combination of aluminum oxide species and metallic Al.
15. Particulate material according to claim 13 or 14 wherein aluminum oxide species are selected from alumina and lithium aluminate.
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