Patent Description:
Several materials have been suggested, such as lithium iron phosphates, lithium co-bait oxides, and lithium nickel cobalt manganese oxides.

Currently, a certain interest in so-called Ni-rich electrode active materials may be observed, for example electrode active materials that contain <NUM> mole-% or more of Ni, referring to the total TM content.

One problem of lithium ion batteries - especially of Ni-rich electrode active materials - is attributed 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, and it may lead to gassing in the electrochemical cell. 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., <CIT>.

Other theories assign undesired reactions to free LiOH or Li<NUM>CO<NUM> on the surface, or to so-called reactive lithium that can be determined by extraction with an aqueous medium. Attempts have been made to remove such free LiOH or Li<NUM>CO<NUM> or reactive lithium by washing the electrode active material with water, see, e.g., <CIT>, <CIT>, and <CIT>. However, in some instances it was observed that the properties of the resultant electrode active materials did not improve or even deteriorated.

In <CIT>, certain cathode active materials are treated with an aqueous solution of LiNO<NUM> and Co(NO<NUM>)<NUM> hexahydrate, followed by calcination. The authors claim that a gradient of LiCoO<NUM> is formed. However, problems resulting from residual or extractable lithium are not solved. Sometimes, slurries of electrode active materials and conductive carbon and binder tend to gelling. Said gelling makes the application of said slurry to current collectors difficult and should be avoided.

It was an objective of the present invention to provide a process for making Ni-containing and, in particular, Ni-rich electrode active materials with excellent electrochemical properties and with a low tendency of gelling.

Accordingly, the process for making an electrode active material defined at the outset has been found, hereinafter also referred to as inventive process. Such electrode active material comprises.

Core (A) and particles (B) will be described in more details below.

In one embodiment of the present invention core (A) has an average particle diameter (D50) in the range of from <NUM> to <NUM>, preferably from <NUM> to <NUM>. The average particle diameter may be determined, e. , 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.

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 description of the present invention. Traces in this context will mean amounts of <NUM> mol-% or less, referring to the total metal content of the TM or of particles (B), respectively.

Core (A) is preferably a nickel-rich electrode active material. Although the percentage of nickel in the core may be <NUM> mole-% or even lower, e.g., <NUM> mole-%, it is preferred that the molar percentage of nickel in the core material is at least <NUM> mole-%, referring to all metals in TM.

TM in the above formula contains at least one of Mn, Co and Al, preferably at least two, e.g., Co and Mn, Co and Al, or even Mn, Co, and Al.

Optionally, TM may contain at least one more metal selected from Mg, Ti, Nb, Ta, and W.

In one embodiment of the present invention, TM is a combination of metals according to general formula (I).

In another embodiment of the present invention, the variable TM corresponds to general formula (I a).

(Nia*Cob*Ale*)<NUM>-d*M<NUM>d*     (I a).

In one embodiment of the present invention TM corresponds to general formula (I) and x1 is in the range from -<NUM> to <NUM>, preferably from zero to <NUM> and even more preferably <NUM> to <NUM>.

In one embodiment of the present invention TM corresponds to general formula (I a) and x1 is in the range of from -<NUM> to zero.

Particles (B) comprise of cobalt oxide compounds in which the average oxidation state of cobalt is higher than +II and lower than +III or higher than +II and lower than +IV and wherein the molar ratio of lithium to cobalt in said particles is in the range of from zero to below <NUM> and wherein said particles are attached to the surface of the core material, thus, to core (A). The oxidation state of cobalt in particles (B) may be determined by X-ray photoelectron spectroscopy ("XPS"), and the property of being attached to core (A) may be determined by imaging processes such as transmission electron microscopy ("TEM") and scanning electron microscopy ("SEM"). The phase type of particles (B) may be determined by high resolution X-ray powder diffraction ("XRD"). In a preferred embodiment, the average molar ratio of lithium to cobalt in particles (B) is in the range of from zero to below <NUM>.

Particles (B) may be incorporated into pores of core (A), fully or partially, or attached to the outer surface.

In one embodiment of the present invention, the average oxidation state of cobalt in particles (B) is in the range of +II to +III, preferably from <NUM> to <NUM>, even more preferably <NUM>.

In one embodiment of the present invention, the average oxidation state of cobalt in particles (B) is in the range of +III to +IV, preferably from <NUM> to <NUM>, even more preferably <NUM>.

The molar ratio of lithium to cobalt in particles (B) is in the range of from zero to <NUM>, preferably from above zero to below <NUM>.

In a preferred embodiment, particles (B) are not composed of a defined compound but a mixture of several cobalt containing oxides, for example, substoichiometric lithium cobalt oxide compounds, furthermore Co<NUM>O<NUM> or LiCo<NUM>O<NUM>, with LiCoO<NUM> and Co<NUM>O<NUM> as optional components.

In one embodiment of the present invention, the weight ratio of core (A) and particles (B) is in the range of from <NUM> : <NUM> to <NUM> to <NUM>, preferably <NUM>:<NUM> to <NUM>:<NUM>.

In one embodiment of the present invention, particles (B) have an average diameter (D50) in the range of from <NUM> to <NUM>, preferably <NUM> to <NUM>. The average diameter (D50) may be determined by imaging processes such as TEM and SEM.

Particles (B) comprise cobalt and lithium and Al and at least one of Ti and Zr as additional elements, and it is preferred that particles (B) comprise more Co than any of Al, Zr. Ti and In particles (B) the molar ratio of Co to the sum of Al and Zr or Ti is in the range of from <NUM>:<NUM> to <NUM>:<NUM>.

In one embodiment electrode active materials made according to the present invention have a surface (BET) in the range of from <NUM> to <NUM><NUM>/g, determined according to DIN-ISO <NUM>:<NUM>-<NUM>. The inventive process comprises at least three steps, (a), (b), and (d), and it may comprise optional step (c), in the context of the present invention also referred to as step (a) and step (b) and step (d) and step (c), respectively. Steps (a) and (b) and, if applicable, (c), and (d) are performed subsequently.

The inventive process comprising the steps of.

Steps (a) to (d) will be explained in more detail below.

The inventive process starts off from an electrode active material according to general formula Li<NUM>-x2TM<NUM>-x2O<NUM>, step (a), wherein providing a material according to general formula Li<NUM>+x2TM<NUM>-x2O<NUM> wherein TM is a combination of Ni and at least one of Mn, Co and Al, and, optionally, at least one more metal selected from Mg, Ti, Zr, Nb, Ta, and W, and x2 is in the range of from zero to <NUM>. Electrode active material according to general formula Li<NUM>+x2TM<NUM>-x2O<NUM> may hereinafter also be referred to as "starting material".

In one embodiment electrode active material made according to the present invention according to general formula Li<NUM>+x2TM<NUM>-x2O<NUM> has an average particle diameter (D50) in the range of from <NUM> to <NUM>, preferably from <NUM> to <NUM>. The average particle diameter may be determined, e. , 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 electrode active material made according to the present invention according to general formula Li<NUM>+x2TM<NUM>-x2O<NUM> has a monomodal particle diameter distribution. In another embodiment electrode active material according to general formula Li<NUM>+x2TM<NUM>-x2O<NUM> has a bimodal particle diameter distribution.

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 <NUM> to <NUM><NUM>/g. The BET surface may be determined by nitrogen adsorption after outgassing of the sample at <NUM> for <NUM> minutes or more and beyond this accordance with DIN ISO <NUM>:<NUM>.

In one embodiment of the present invention, the starting material has a moisture content in the range of from <NUM> to <NUM>,<NUM> ppm, determined by Karl-Fischer titration, preferred are <NUM> to <NUM>,<NUM> ppm.

The starting material provided in step (a) is usually free from conductive carbon, that means that the conductive carbon content of starting material is less than <NUM>% by weight, referring to said starting material, preferably <NUM> to <NUM> % by weight.

Again, 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. Traces in this context will mean amounts of <NUM> mol-% or less, referring to the total metal content of the starting material.

In step (b), said material is contacted with an oxide or (oxy)hydroxide or nitrate of cobalt and, up to <NUM> % by vol of water and at least one oxide or hydroxide or oxyhydroxide of Al and Ti or Zr. Such contacting is achieved by adding said an oxide or hydroxide of cobalt and up to <NUM> % by vol of water and at least one oxide or hydroxide or oxyhydroxide of Al and Ti or Zr to the starting material, followed by mixing.

In step (b), preferably no compound of lithium is added.

Examples of oxides and (oxy)hydroxides of cobalt are CoO, Co<NUM>O<NUM>, Co(OH)<NUM>, CoOOH, non-stoichiometric oxyhydroxides of cobalt. Preferred is Co<NUM>O<NUM>. An example of cobalt nitrate is Co(NO<NUM>)<NUM>. Water of crystallinity is omitted for legibility purposes.

Examples of optionally added oxide or (oxy)hydroxide or nitrates of Ti, Zr or Al are TiO<NUM>, Ti<NUM>O<NUM>, TiO(OH)<NUM>, TiO<NUM>·aq, Al<NUM>O<NUM>, AIOOH, Al(OH)<NUM>, Al<NUM>O<NUM>·aq, ZrO<NUM>, Zr(OH)<NUM>, and ZrO<NUM>·aq, and AlONO<NUM>, Al(NO<NUM>)<NUM>, TiO(NO<NUM>)<NUM>, Ti(NO<NUM>)<NUM>, ZrO(NO<NUM>)<NUM> and Zr(NO<NUM>)<NUM>.

In one embodiment of the present invention, step (b) is performed by adding an aqueous slurry of an oxide or (oxy)hydroxide of cobalt or an aqueous solution of a nitrate of cobalt and of at least one oxide or hydroxide or oxyhydroxide of Al and of Zr or Ti to the starting material, followed by mixing.

In one embodiment of the present invention, step (b) is performed by adding an aqueous slurry of an oxide or (oxy)hydroxide of cobalt or an aqueous solution of a nitrate of cobalt and one oxide or hydroxide or oxyhydroxide of Al and Ti or Zr to the starting material, followed by mixing, wherein the molar amount of Co is higher than the molar amount of Ti, Zr or Al, respectively.

Even more preferably, wherein the molar amount of Co is higher than the molar amount of Ti, Zr and Al.

In one embodiment of the present invention, step (b) is performed in a mixer, for example a paddle mixer, a plough-share mixer, a free-fall mixer, a roller mill, or a high-shear mixer. Free fall mixers are using the gravitational force to achieve mixing. Plough-share mixers are preferred.

In one embodiment of the present invention the mixer operates in step (b) with a speed in the range of from <NUM> to <NUM> revolutions per minute ("rpm"), preferred are <NUM> to <NUM> rpm. In embodiments wherein a free-fall mixer is applied, from <NUM> to <NUM> rpm are more preferred and <NUM> to <NUM> rpm are even more preferred. In embodiments wherein a plough-share mixer is applied, <NUM> to <NUM> rpm are preferred and <NUM> to <NUM> rpm are even more preferred. In the case of high-shear mixers, <NUM> to <NUM> rpm of the agitator and <NUM> to <NUM>,<NUM> rpm of the chopper are preferred.

In one embodiment of the present invention, step (b) is performed in the presence of minor amounts of a solvent, for example, water. Minor amount refers to up to <NUM> % by volume, referring to the entire solids content of the mixture, preferred are <NUM> to <NUM>% by volume.

In one embodiment of the present invention, the duration of step (b) is in the range of from one minute to <NUM> hours, preferred are ten minutes to one hour.

In one embodiment of the present invention, step (b) is preferred at a temperature in the range of from <NUM> to <NUM>. Even more preferred is ambient temperature.

In one embodiment of the present invention, step (b) is performed in an air atmosphere, or under an inert gas such as nitrogen. Ambient air is preferred.

From step (b), a mixture is obtained. In embodiments in which water is used the mixture has the appearance of a moist powder.

In the optional step (c), water or solvent is removed at least partially from the mixture obtained from step (b), for example by evaporation. In a preferred embodiment of step (c), the water is evaporated at least partially at a temperature in the range of from <NUM> to <NUM>. Preferably, water evaporation is performed at normal pressure.

In one embodiment of the present invention, step (d) is performed at a temperature in the range of from <NUM> to <NUM>, preferably <NUM> to <NUM>.

In one embodiment of the present invention, the temperature is ramped up before reaching the desired temperature of from <NUM> to <NUM>, preferably <NUM> to <NUM>. For example, first the mixture of step (b) or (c) is heated to a temperature to <NUM> to <NUM> and then held constant for a time of <NUM> to <NUM> hours, and then it is raised to <NUM> to <NUM>.

In one embodiment of the present invention, the heating rate in step (d) is in the range of from <NUM> to <NUM>/min.

In one embodiment of the present invention, step (d) is performed in a roller hearth kiln, a pusher kiln or a rotary kiln or a combination of at least two of the foregoing. Rotary kilns have the advantage of a very good homogenization of the material made therein. In roller hearth kilns and in pusher kilns, different reaction conditions with respect to different steps may be set quite easily. In lab scale trials, box-type and tubular furnaces and split tube furnaces are feasible as well.

In one embodiment of the present invention, step (d) is performed in an oxygen-containing atmosphere, for example in a nitrogen-air mixture, in a rare gas-oxygen mixture, in air, in oxygen or in oxygen-enriched air. In a preferred embodiment, the atmosphere in step (b) is selected from air, oxygen and oxygen-enriched air. Oxygen-enriched air may be, for example, a <NUM>:<NUM> by volume mix of air and oxygen. Other options are <NUM>:<NUM> by volume mixtures of air and oxygen, <NUM>:<NUM> by volume mixtures of air and oxygen, <NUM>:<NUM> by volume mixtures of air and oxygen, and <NUM>:<NUM> by volume mixtures of air and oxygen.

In one embodiment of the present invention, step (d) is carried out under an atmosphere with reduced CO<NUM> content, e.g., a carbon dioxide content in the range of from <NUM> to <NUM> ppm by weight, preferred are <NUM> to <NUM> ppm by weight. The CO<NUM> 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, step (d) has a duration in the range of from one hour to <NUM> hours. Preferred are <NUM> minutes to <NUM> hours. The cooling time is neglected in this context.

After thermal treatment in accordance to step (d), the electrode active material so obtained is cooled down before further processing.

By performing the inventive process electrode active materials with excellent properties are available through a straightforward process. Preferably, the electrode active materials so obtained have a surface (BET) in the range of from <NUM> to <NUM><NUM>/g, determined according to DIN-ISO <NUM>:<NUM>-<NUM>.

Without wishing to be bound by any theory, it is assumed that extractable lithium and especially residual lithium is at least partially drawn to the surface and reacted with Co to Co-Li-containing oxide species.

Further disclosed are electrodes comprising at least one electrode active material made according to the present invention. They are particularly useful for lithium ion batteries. Lithium ion batteries comprising at least one such electrode exhibit a good discharge behavior. Electrodes comprising at least one electrode active material are hereinafter also referred to as cathodes made according to the present invention.

Cathodes made 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 <NUM>,<NUM>-butadiene. Polypropylene is also suitable. Polyisoprene and polyacrylates are additionally suitable. Particular preference is given to polyacrylonitrile.

In this context, polyacrylonitrile is understood to mean not only polyacrylonitrile homopolymers but also copolymers of acrylonitrile with <NUM>,<NUM>-butadiene or styrene. Preference is given to polyacrylonitrile homopolymers.

In this context, polyethylene is not only understood to mean homopoly-ethylene, but also copolymers of ethylene which comprise at least <NUM> mol% of copolymerized ethylene and up to <NUM> mol% of at least one further comonomer, for example α-olefins such as propylene, butylene (<NUM>-butene), <NUM>-hexene, <NUM>-octene, <NUM>-decene, <NUM>-dodecene, <NUM>-pentene, and also isobutene, vinylaromatics, for example styrene, and also (meth)acrylic acid, vinyl acetate, vinyl propionate, C<NUM>-C<NUM>-alkyl esters of (meth)acrylic acid, especially methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-butyl acrylate, <NUM>-ethylhexyl acrylate, n-butyl methacrylate, <NUM>-ethylhexyl methacrylate, and also maleic acid, maleic anhydride and itaconic anhydride. Polyethylene may be HDPE or LDPE.

In this context, polypropylene is not only understood to mean homopolypropylene, but also copolymers of propylene which comprise at least <NUM> mol% of copolymerized propylene and up to <NUM> mol% of at least one further comonomer, for example ethylene and α-olefins such as butylene, <NUM>-hexene, <NUM>-octene, <NUM>-decene, <NUM>-dodecene and <NUM>-pentene. Polypropylene is preferably isotactic or essentially isotactic polypropylene.

In this context, polystyrene is not only understood to mean homopolymers of styrene, but also copolymers with acrylonitrile, <NUM>,<NUM>-butadiene, (meth)acrylic acid, C<NUM>-C<NUM>-alkyl esters of (meth)acrylic acid, divinylbenzene, especially <NUM>,<NUM>-divinylbenzene, <NUM>,<NUM>-diphenylethylene and α-methylstyrene.

Another preferred binder is polybutadiene.

Other suitable binders are selected from polyethylene oxide (PEO), cellulose, carboxymethylcellulose, polyimides and polyvinyl alcohol.

In one embodiment, binder is selected from those (co)polymers which have an average molecular weight Mw in the range from <NUM>,<NUM> to <NUM>,<NUM>,<NUM>/mol, preferably to <NUM>,<NUM>/mol.

Binder may be cross-linked or non-cross-linked (co)polymers.

In a particularly preferred embodiment, binder is selected from halogenated (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 atom per molecule, more preferably at least two halogen atoms or at least two fluorine atoms per molecule. Examples are polyvinyl chloride, polyvinylidene chloride, polytetrafluoroethylene, polyvinylidene 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 copolymers.

Suitable binders are especially polyvinyl alcohol and halogenated (co)polymers, for example polyvinyl chloride or polyvinylidene chloride, especially fluorinated (co)polymers such as polyvinyl fluoride and especially polyvinylidene fluoride and polytetrafluoroethylene.

The cathodes may comprise <NUM> to <NUM>% by weight of binder(s), referring to electrode active material. In other embodiments, cathodes may comprise <NUM> up to less than <NUM>% by weight of binder(s).

A further aspect is a battery, containing at least one cathode comprising electrode active material made according to the present invention, carbon, and binder, at least one anode, and at least one electrolyte.

Embodiments of the cathodes have been described above in detail. Said anode may contain at least one anode active material, such as carbon (graphite), TiO<NUM>, 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 is preferably 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-C<NUM>-C<NUM>-alkylene glycols and in particular polyethylene glycols. Polyethylene glycols can here comprise up to <NUM> mol% of one or more C<NUM>-C<NUM>-alkylene glycols. Polyalkylene glycols are preferably polyalkylene glycols having two methyl or ethyl end caps.

The molecular weight Mw of suitable polyalkylene glycols and in particular suitable polyethylene glycols can be up to <NUM><NUM><NUM>/mol, preferably up to <NUM><NUM><NUM>/mol.

Examples of suitable cyclic organic carbonates are compounds according to the general formulae (II) and (III)
<CHM>
<CHM>
where R<NUM>, R<NUM> and R<NUM> can be identical or different and are selected from among hydrogen and C<NUM>-C<NUM>-alkyl, for example methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl and tert-butyl, with R<NUM> and R<NUM> preferably not both being tert-butyl.

Electrolyte (C) further comprises at least one electrolyte salt. Suitable electrolyte salts are, in particular, lithium salts. Examples of suitable lithium salts are LiPF<NUM>, LiBF<NUM>, LiClO<NUM>, LiAsF<NUM>, LiCF<NUM>SO<NUM>, LiC(CnF2n+<NUM>SO<NUM>)<NUM>, lithium imides such as LiN(CnF2n+<NUM>SO<NUM>)<NUM>, where n is an integer in the range from <NUM> to <NUM>, LiN(SO<NUM>F)<NUM>, Li<NUM>SiF<NUM>, LiSbF<NUM>, LiAlCl<NUM> and salts of the general formula (CnF2n+<NUM>SO<NUM>)tYLi, where m is defined as follows:.

In an embodiment, batteries comprise one or more separators by means of which the electrodes are mechanically separated. Suitable separators 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 <NUM> to <NUM>%. Suitable pore diameters are, for example, in the range from <NUM> to <NUM>.

In another embodiment, separators can be selected from among PET nonwovens filled with inorganic particles. Such separators can have porosities in the range from <NUM> to <NUM>%. Suitable pore diameters are, for example, in the range from <NUM> to <NUM>.

Batteries 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 display a good discharge behavior, for example at low temperatures (zero °C or below, for example down to -<NUM> or even less), a very good discharge and cycling behavior.

Batteries can comprise two or more electrochemical cells that combined 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 disclosure. Preferably, in electrochemical cells, the majority of the electrochemical cells contains a cathode according to the present disclosure.

Even more preferably, in batteries herein disclosed all the electrochemical cells contain cathodes comprising an electrode active material made according to the present invention.

The present invention is further illustrated by the following working examples.

A stirred tank reactor was filled with deionized water and <NUM> of ammonium sulfate per kg of water. The solution was tempered to <NUM> and a pH value of <NUM> 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 <NUM>, and a total flow rate resulting in a residence time of <NUM> hours. The transition metal solution contained Ni, Co and Mn at a molar ratio of <NUM>:<NUM>:<NUM> and a total transition metal concentration of <NUM> mol/kg. The aqueous sodium hydroxide solution was a <NUM> wt. % sodium hydroxide solution and <NUM> wt. % ammonia solution in a weight ratio of <NUM>. The pH value was kept at <NUM> by the separate feed of an aqueous sodium hydroxide solution. Beginning with the start-up of all feeds, mother liquor was removed continuously. After <NUM> hours all feed flows were stopped. The mixed transition metal (TM) oxyhydroxide precursor TM-OH. <NUM> was obtained by filtration of the resulting suspension, washing with distilled water, drying at <NUM> in air and sieving.

P (pristine): The mixed transition metal oxyhydroxide precursor obtained according to I. <NUM> was mixed with <NUM> mole-% TiO<NUM> (average primary particle diameter <NUM>), <NUM> mole-% of amorphous Zr(OH)<NUM>, both mole-% referring to the sum of Ni, Co and Mn in TM-OH. <NUM> and LiOH monohydrate in a Li/(TM) molar ratio of <NUM>. The mixture was heated to <NUM> and kept for <NUM> hours in a forced flow of oxygen to obtain the electrode active material CAM.

D50 = <NUM> determined using the technique of laser diffraction in a Mastersizer <NUM> instrument from Malvern Instruments. Residual moisture at <NUM> was determined to be <NUM> ppm.

A Lödige plough share mixer was charged with <NUM>,<NUM> CAM. P, <NUM> of Co(NO<NUM>)<NUM>·<NUM><NUM>O, <NUM> of Al(NO<NUM>)<NUM> and <NUM> of TiO<NUM>. <NUM> of water were added. The plough share mixer was set to <NUM> RPM for <NUM> minutes. Then, a mixed powder was obtained.

The mixed powder was heat treated at a treatment temperature of <NUM> for two hours in oxygen. The heating rate was <NUM>/min. Then, the resultant CAM. <NUM> was allowed to cool down to ambient temperature.

SEM/EDX analysis revealed that sub-micron sized coating material particles (B. <NUM>) of Al<NUM>O<NUM>, TiO<NUM> and were distributed along the surface of CAM.

Positive electrode: PVDF binder (Solef® <NUM>) was dissolved in NMP (Merck) to produce a <NUM> wt. % solution. For electrode preparation, binder solution (<NUM> wt. %), graphite (SFG6L, <NUM> wt. %), and carbon black (Super C65, <NUM> wt. -%) were suspended in NMP. After mixing using a planetary centrifugal mixer (ARE-<NUM>, Thinky Corp. ; Japan), inventive CAM. <NUM> or a comparative cathode active material CAM. P (<NUM> wt. %) was added and the suspension was mixed again to obtain a lump-free slurry. The solid content of the slurry was adjusted to <NUM>%. The slurry was coated onto Al foil using a roll-to-roll coater. Prior to use, all electrodes were calendared. The thickness of cathode material was <NUM>, corresponding to <NUM>/cm<NUM>. All electrodes were dried at <NUM> for <NUM> hours before battery assembly.

Graphite and carbon black were thoroughly mixed. CMC (carboxymethyl cellulose) aqueous solution and SBR (styrene butadiene rubber) aqueous solution were used as binder. The mixture of graphite and carbon black, weight ration cathode active material: carbon : CMC : SBR like <NUM>:<NUM>:<NUM>:<NUM>, was mixed with the binder solutions and an adequate amount of water was added to prepare a suitable slurry for electrode preparation. The thus obtained slurry was coated by using a roll coater onto copper foil (thickness = <NUM>) and dried under ambient temperature. The sample loading for electrodes on Cu foil was fixed to be <NUM> cm-<NUM> for single layer pouch cell testing.

A base electrolyte composition was prepared containing <NUM> wt% of LiPF<NUM>, <NUM> wt% of ethylene carbonate (EC), and <NUM> wt% of ethyl methyl carbonate (EMC) (EL base <NUM>), based on the total weight of EL base <NUM>. To this base electrolyte formulation, <NUM> wt. % of vinylene carbonate (VC) was added (EL base <NUM>).

Coin-type half cells (<NUM> in diameter and <NUM> in thickness) comprising a cathode prepared as described under !!!. <NUM> and lithium metal as working and counter electrode, respectively, were assembled and sealed in an Ar-filled glove box. In addition, the cathode and anode and a separator were superposed in order of cathode // separator // Li foil to produce a half coin cell. Thereafter, <NUM> of the EL base <NUM> which is described above (III. <NUM>) were introduced into the coin cell.

Single layer pouch cells (<NUM> mA·h) comprising an anode prepared as described above in <NUM>. <NUM> and a graphite electrode according to !!!. <NUM>, were assembled and sealed in an Ar-filled glove box. The cathode and the anode and a separator were superposed in order of cathode // separator // anode to produce a several layer-pouch cell. Thereafter, <NUM> of the EL base <NUM> electrolyte were introduced into the Laminate pouch cell.

Cell performance were evaluated using the produced coin type battery. For the battery performances, initial capacity and reaction resistance of cell were measured.

The initial performance and cycle were measured as follows:
Coin half cells according to <NUM>. <NUM> were tested in a voltage range between <NUM> V to <NUM> V at room temperature. For the initial cycles, the initial lithiation was conducted in the CC-CV mode, i.e., a constant current (CC) of <NUM> C was applied until reaching <NUM> C. After <NUM> resting time, reductive lithiation was carried out at constant current of <NUM> C up to <NUM> V. For the cycling, the current density is <NUM> C. The results are summarized in Table <NUM>.

Single-layer pouch cells according to II. <NUM> were charged to <NUM> % state of charge, stored at <NUM> for <NUM> hours and then measured for gassing.

Single layer pouch cells (<NUM> mA h) comprising an anode prepared as described above in !!!. <NUM> and a graphite electrode according to !!!. <NUM>, were assembled and sealed in an Ar-filled glove box. The cathode and the anode and a separator were superposed in order of cathode // separator // anode to produce a several layer-pouch cell. Thereafter, <NUM> of the EL base <NUM> electrolyte were introduced into the Laminate pouch cell.

Claim 1:
Process for making an electrode active material that comprise
(A) a core material according to general formula Li<NUM>+x1TM<NUM>-x1O<NUM> wherein TM is a combination of Ni and at least one of Mn, Co and Al, and, optionally, at least one more metal selected from Mg, Ti, Zr, Nb, Ta, and W, and x1 is in the range of from -<NUM> to <NUM>, and
(B) particles of cobalt compound(s) and of aluminum compound(s) and of titanium compound(s) or zirconium compound(s) wherein the molar ratio of lithium to cobalt in said particles is in the range of from zero to below <NUM> and wherein in particles (B) the molar ratio of Co to the sum of Al and Zr or Ti is in the range of from <NUM>:<NUM> to <NUM>:<NUM>, and wherein said particles are attached to the surface of the core material,
said process comprising the steps of
(a) providing a material according to general formula Li<NUM>+x2TM<NUM>-x2O<NUM> wherein TM is a combination of Ni and at least one of Mn, Co and Al, and, optionally, at least one more metal selected from Mg, Ti, Zr, Nb, Ta, and W, and x2 is in the range of from zero to <NUM>,
(b) contacting said material with an oxide or (oxy)hydroxide or nitrate of cobalt and up to <NUM> % by vol of water and with at least one oxide or (oxy)hydroxide or nitrate of Al and Ti or Zr,
(c) removing water from the mixture obtained in step (b),
(d) calcining the intermediate of step (c).