Patent Description:
wherein either step (d) is performed or the aqueous medium in step (b) contains a heteropoly acid or a compound of Al or Sb, or both.

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. 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. Attempts have been made to remove such free LiOH or Li<NUM>CO<NUM> 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.

In <CIT>, a treatment of a cathode active material with boric acid is disclosed. In <CIT>, a process is disclosed in which a cathode active material is coated with boric acid.

It was an objective of the present invention to provide a process for making 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, especially a low resistance growth upon cycling.

Accordingly, the process defined at the outset has been found, hereinafter also referred to as "inventive process". The inventive process comprises the following steps:.

wherein either step (d) is performed or the aqueous medium in step (b) contains a heteropoly acid or a compound of Al or Sb or both, which means that step (d) is performed and the aqueous medium in step (b) contains a heteropoly acid or a compound of Al or Sb.

The inventive process comprises at least five steps, (a), (b), (c), (f), and (g), in the context of the present invention also referred to as step (a) and step (b) and step (c) and step (f) and step (g), respectively. Steps (a) to (g) are performed subsequently. Steps (d) and (e) are optional.

In step (a), the inventive process starts off from an electrode active material according to general formula Li<NUM>+xTM<NUM>-xO<NUM>, wherein TM comprises Ni and, optionally, at least one transition metal selected from Co and Mn, and, optionally, at least one element selected from Al, Mg and Ba, and, wherein at least <NUM> mole-% of TM is Ni, preferably at least <NUM> mole-%, and x is in the range of from zero to <NUM>. Said material is hereinafter also referred to as starting material.

In one embodiment of the present invention the starting material has an average particle diameter (D50) in the range of from <NUM> to <NUM>, preferably from <NUM> to <NUM>. The average particle diameter can 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 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 particulate material provided in step (a) 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.

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

In one embodiment of the present invention, the variable c is zero, M is Al, and d is in the range of from <NUM> to <NUM>.

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

The variable x in formula (I a) is in the range of from zero to <NUM>, preferably from <NUM> to <NUM>.

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

In one embodiment of the present invention, TM is selected from Ni<NUM>Co<NUM>Mn<NUM>, Ni<NUM>Co<NUM>Mn<NUM>, Ni<NUM>Co<NUM>Mn<NUM>, Ni<NUM>Co<NUM>Mn<NUM>, Ni<NUM>Co<NUM>Al<NUM>, Ni<NUM>Co<NUM>Al<NUM> and Ni<NUM>Co<NUM>Mn<NUM>.

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 <NUM>% by weight, referring to said starting material, preferably <NUM> to <NUM> % 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 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 starting material.

In step (b), said electrode active material provided in step (a) is treated with an aqueous medium, preferably with water. Said aqueous medium may have a pH value in the range of from <NUM> up to <NUM>, preferably at least <NUM>, more preferably from <NUM> to <NUM>. The pH value is measured at the beginning of step (b). It is observed that in the course of step (b), the pH value raises to at least <NUM>, for example <NUM> to <NUM>. In embodiments wherein the pH value is in the range of from <NUM> to <NUM> at the beginning of step (b) it raises to more than <NUM> to up to <NUM>. In embodiments wherein the pH value is in the range of <NUM> to below <NUM> at the beginning of step (b) it raises to <NUM> to up to <NUM> in the course of step (b).

It is preferred that the water hardness of said aqueous medium used in step (b) is at least partially removed, especially calcium. The use of desalinized water is preferred.

In one embodiment of the present invention, said aqueous medium may contain at least one heteropoly acid, or its respective ammonium or lithium salt, or a compound selected from compounds of Al or Sb, dissolved or slurried.

In one embodiment of the present invention, heteropoly acid present in step (b) is selected from phosphotungstic acid, phosphomolybdic acid, tungstosilicic acid, molybdosilicic acid and combinations of at least two of the foregoing, and their respective ammonium and lithium salts, for example the mono-, di- or triammonium salts and the mono-, di- and trilithium salts. Preferred are heterpolyacids of tungsten, especially phosphotungstic acid and tungstosilicic acid and their respective ammonium and lithium salts, for example the mono-, di- or triammonium salts.

Examples of heteropoly acids are M<NUM><NUM>[PW<NUM>O<NUM>], M<NUM>[PW<NUM>O<NUM>], M<NUM><NUM>[SiW<NUM>O<NUM>], M<NUM><NUM>[SiW<NUM>O<NUM>], M<NUM><NUM>[(W<NUM>O<NUM>), M<NUM><NUM>(P<NUM>W<NUM>O<NUM>), M<NUM><NUM>(PW<NUM>O<NUM>), M<NUM><NUM>(SiW<NUM>O<NUM>), M<NUM><NUM>(P<NUM>W<NUM>O<NUM>); M<NUM><NUM>(PW<NUM>O<NUM>), and M<NUM><NUM>(SiW<NUM>O<NUM>), with M<NUM> being selected from H, NH<NUM>+, Li and combinations of at least two of the foregoing. Possible are embodiments as well where M<NUM> is selected from Al, Ga, In, Ba, and the stoichiometric coefficients are adjusted accordingly.

In one embodiment of the present invention, the amount of heteropoly acid or compound of Al or Sb is in the range of from <NUM> to <NUM> mol-%, preferably <NUM> to <NUM> mol-%, referring to TM.

Examples of compounds of Al or Sb used in step (b) are selected from water-soluble and water-insoluble compounds. Examples of water-soluble compounds of Al are Al<NUM>(SO<NUM>)<NUM>, KAl(SO<NUM>)<NUM>, or Al(NO<NUM>)<NUM>. "Water-soluble" in this context means a solubility of at least <NUM> Al or Sb, respectively, compound/I water at <NUM>.

In other embodiments, said inorganic compound of Al is water-insoluble. "Water-insoluble" in this context means a solubility of less than <NUM> compound of Al/l water at <NUM>. Examples are, e.g., Al<NUM>O<NUM>, Al(OH)<NUM>, AIOOH, Al<NUM>O<NUM>·aq, preference being given to AIOOH and Al<NUM>O<NUM>.

Examples of water-insoluble compounds of Sb are compounds of Sb(+Ill) and of Sb(+V). Examples of compounds of Sb(+III) are Sb(OH)<NUM>, Sb<NUM>O<NUM>·aq, Sb<NUM>(SO<NUM>)<NUM>, SbOOH, LiSbO<NUM>, and Sb<NUM>O<NUM>. Examples of compounds of Sb(+V) are Sb<NUM>O<NUM>, LiSb<NUM>O<NUM>, LiSbO<NUM>, Li<NUM>SbO<NUM>, Li<NUM>SbO<NUM>, Li<NUM>SbO<NUM>, Sb<NUM>O<NUM> (Sb(III)Sb(V)O<NUM>), and oxyhydroxides of Sb(+V) such as, but not limited to SbO(OH)<NUM>, Sb<NUM>O<NUM>(OH)<NUM>, Sb<NUM>O<NUM>(OH)<NUM>, Sb<NUM>O<NUM>OH, Sb<NUM>O<NUM>OH. Preferred are Sb(OH)<NUM>, Sb<NUM>O<NUM>. aq and Sb<NUM>O<NUM>. Examples of water-soluble compounds are Sb<NUM>(SO<NUM>)<NUM>, SbONO<NUM>, and Sb(NO<NUM>)<NUM>.

Said water-insoluble compound of Al or Sb may be dispersed or slurried in water.

In the context of the present invention, AIOOH does not necessarily bear equal molar amounts of oxide and hydroxide and is sometimes also named as Al(O)(OH). The same applies mutatis mutandis to SbOOH.

Compounds of Al or Sb, respectively, and especially Al<NUM>O<NUM> and Al(O)(OH) used in step (b) may be pure (≥ <NUM> mole% Al, referring to total metals including Si) or doped with oxides such as La<NUM>O<NUM>, Ce<NUM>O<NUM>, titania or zirconia, in amounts of for example <NUM> to <NUM> mole%.

More preferred compounds of Al and Sb in step (b) are Al<NUM>(SO<NUM>)<NUM> and Sb<NUM>O<NUM>.

In one embodiment of the present invention, said water-insoluble compound of Al or Sb has an average particle 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 SEM.

In another embodiment, said aqueous medium does not contain any of heteropoly acids or the respective lithium or ammonium salts or compounds of Al or Sb, neither dissolved nor slurried.

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

In one embodiment of the present invention, step (b) is performed at normal pressure. It is preferred, though, to perform step (b) under elevated pressure, for example at <NUM> mbar to <NUM> bar above normal pressure, or with suction, for example <NUM> to <NUM> mbar below normal pressure, preferably <NUM> to <NUM> mbar below normal pressure.

Step (b) 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, in step (b), the amounts of water and electrode active material have a weight ratio in the range of from <NUM>:<NUM> to <NUM>:<NUM>, preferably from <NUM>:<NUM> to <NUM>:<NUM>.

Step (b) 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 (b) has a duration in the range of from <NUM> minute to <NUM> minutes, preferably <NUM> minute to less than <NUM> minutes. A duration of <NUM> minutes or more is possible in embodiments wherein in step (b), water treatment and water removal are performed overlapping or simultaneously.

In one embodiment of the present invention, treatment according to step (b) and water removal according to step (c) are performed consecutively.

After or during the treatment with an aqueous medium in accordance to step (b), 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 <NUM> minutes after commencement of step (b), step (c) is started. Step (c) includes partially removing the water from treated particulate material, for example by way of a solid-liquid separation, for example by decanting or preferably by filtration. Said "partial removal" may also be referred to as partially separating off.

In one embodiment of step (c), the slurry obtained in step (b) 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 filter press or in a belt filter that is located preferably directly below the vessel in which step (b) is performed. Then, filtration is commenced.

In a particularly preferred embodiment of the present invention, steps (b) and (c) are performed in a filter press or in a filter device with stirrer, for example a pressure filter with stirrer or a suction filter with stirrer (German for example: "Rührfilternutsche"). At most <NUM> minutes after, preferably at most <NUM> minutes after - or even immediately after - having combined starting material and aqueous medium in accordance with step (b), removal of aqueous medium is commenced by starting the filtration. On laboratory scale, steps (b) and (c) may be performed on a Büchner funnel, and steps (b) and (c) may be supported by manual stirring.

In a preferred embodiment, step (b) 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.

In one embodiment of the present invention, the water removal in accordance to step (c) has a duration in the range of from <NUM> minute to <NUM> hour.

In one embodiment of the present invention, stirring in step (b) - and (c), if applicable - is performed with a rate in the range of from <NUM> to <NUM> revolutions per minute ("rpm"), preferred are <NUM> to <NUM> rpm. In other embodiments, it is <NUM> to <NUM> 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, steps (b) and (c) are 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 steps (b) and (c) under an atmosphere with a carbon dioxide content below detection limit for example with infrared-light based optical methods.

From step (c), a solid residue is obtained, preferably in the form of a wet filter cake. The moisture content of the solid residue and especially of the filter cake may be in the range of from <NUM> to <NUM> % by weight, preferably <NUM> to <NUM> % by weight.

In the optional step (d), said at least one compound of Al or Sb, preferably in the absence of solvent or with up to <NUM> % by volume of solvent, is added to the solid residue resulting from step (c), with in step (a). In this context, the term solvent refers to liquids at the temperature of step (d) and encompasses organic solvents and water and mixtures thereof. The percentage refers to the volume of solid residue resulting from step (c).

In one embodiment of the present invention, step (d) is performed by adding a concentrated aqueous slurry or paste of an oxide or (oxy)hydroxide of Al or Sb or a solution of a heteropoly acid to the solid residue resulting from step (c).

In one embodiment of the present invention, step (d) is performed in a mixer, for example in 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 (d) 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, the duration of step (d) 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 (d) 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 (d) is performed in an air atmosphere, or under an inert gas such as nitrogen. Ambient air is preferred.

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

Examples of particulate compounds of Sb are Sb(OH)<NUM>, Sb<NUM>O<NUM>·aq, Sb<NUM>(SO<NUM>)<NUM>, SbOOH, LiSbO<NUM>, and Sb<NUM>O<NUM>. Examples of compounds of Sb(+V) are Sb<NUM>O<NUM>, LiSb<NUM>O<NUM>, LiSbO<NUM>, Li<NUM>SbO<NUM>, Li<NUM>SbO<NUM>, Li<NUM>SbO<NUM>, Sb<NUM>O<NUM> (Sb(III)Sb(V)O<NUM>), and oxyhydroxides of Sb(+V) such as, but not limited to SbO(OH)<NUM>, Sb<NUM>O<NUM>(OH)<NUM>, Sb<NUM>O<NUM>(OH)<NUM>, Sb<NUM>O<NUM>OH, and Sb<NUM>O<NUM>OH.

Examples of particulate compounds of Al are Al<NUM>O<NUM>, Al(OH)<NUM>, AIOOH, Al<NUM>O<NUM>·aq, preference being given to AIOOH and Al<NUM>O<NUM>.

More preferred compounds of Al and Sb in step (d) are Al<NUM>(SO<NUM>)<NUM> and Sb<NUM>O<NUM>.

In one embodiment of the present invention, the weight ratio of solid residue material from step (c) and heteropoly acid or compound of Al or Sb 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, compound of Al or Sb in step (d) is particulate and has 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 SEM.

From step (b), a mixture is obtained. In embodiments in which water is used the mixture has the appearance of a moist powder. By performing step (d) least one element - Sb, Al or the respective elements from heteropoly acid - is deposited on the solid residue resulting from step (c).

In an optional step (e), water or solvent is removed at least partially from the mixture obtained from step (d), for example by evaporation. In a preferred embodiment of step (e), the water is evaporated at least partially at a temperature in the range of from <NUM> to <NUM>. Preferably, water evaporation is performed at <NUM> to <NUM> mbar ("in vacuum").

In step (f), at least one compound selected from B<NUM>O<NUM>, boric acid and lithium borates is added to the solid material obtained from step (e), if applicable, or from step (d) or (c), respectively,
thereby depositing B on the surface of said particulate electrode active. Such compound may be added as a slurry or solution or as dry powder, preferred are dry powders.

Thus, step (f) is performed on the solid material obtained from step (e) if a step (e) is performed. In embodiments wherein no step (e) is performed, step (f) is performed on the mixture obtained from step (d) if applicable. In embodiments wherein neither step (d) not step (e) is performed, step (f) is performed on the solid material obtained from step (c).

Examples of compounds of boron are B<NUM>O<NUM>, boric acid (B(OH)<NUM>) and lithium borates, for example LiBO<NUM>. Boric acid is preferred.

In one embodiment of the present invention, B<NUM>O<NUM>, boric acid or lithium borate is added as a particulate solid, for example as a dry powder. Especially in embodiments wherein a step (e) has been performed step (f) is performed by adding B<NUM>O<NUM>, boric acid or lithium borate as a dry powder. "Dry powder" refers to a residual moisture content of <NUM>% by weight or less, determined by Karl-Fischer titration.

Step (f) may be supported by mixing operations, for example shaking or in particular by stirring or shearing or milling, see below.

In one embodiment of the present invention, step (f) has a duration in the range of from <NUM> minute to <NUM> minutes, preferably <NUM> minute to less than <NUM> minutes. A duration of <NUM> minutes or more is possible in embodiments wherein in step (f), water treatment and water removal are performed overlapping or simultaneously.

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

In one embodiment of the present invention, steps (c) to (f) are performed in the same type of vessel, for example in a filter device with stirrer, for example a pressure filter with stirrer or a suction filter with stirrer.

The inventive process includes a subsequent step (g):
(g) thermal treatment of the material obtained from step (f).

Said step (g) is particularly preferred in embodiments wherein said compound(s) of Al or B or Sb or heteropoly acid are added as aqueous slurry or aqueous solution.

Step (g) may be carried out in any type of oven, for example a roller hearth kiln, a pusher kiln, a rotary kiln, a pendulum kiln, or - for lab scale trials - in a muffle oven.

The temperature of the thermal treatment according to step (g) may be in the range of from <NUM> to <NUM>, preferably <NUM> to <NUM> and even more preferably from <NUM> to <NUM>. Said temperature refers to the maximum temperature of step (g).

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 (f) 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>, preferably <NUM> to <NUM>.

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

In one embodiment of the present invention, step (g) 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 (g) 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 or in pure oxygen. In a preferred embodiment, the atmosphere in step (g) 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. Pure oxygen is even more preferred.

In one embodiment of the present invention, step (g) has a duration in the range of from <NUM> minutes to <NUM> hours. Preferred are <NUM> minutes to <NUM> hours. The cooling time is neglected in this context.

By carrying out the inventive process, electrode active materials are obtained with excellent electrochemical properties. Without wishing to be bound by any theory, we assume that the decomposition products of heteropoly acid or of B or Sb or Al - as the case may be - may lead to scavenging lithium compounds deposited at the surface of the electrode active material.

Cathode active materials obtained by the inventive process have numerous advantages. Cathodes made from such cathode active materials display a reduced resistance growth upon cycling.

The invention is further illustrated by working examples.

General remarks: N-methyl-<NUM>-pyrrolidone: NMP.

H<NUM>(SiW<NUM>O<NUM>)·nH<NUM>O (n=<NUM>) was dissolved in water. The resulting solution is named "SiW<NUM> aq".

Ultra-dry air: dehumidified air, dew point of less than -<NUM>, and CO<NUM> content less than <NUM> ppm "in vacuo": <NUM> to <NUM> mbar.

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) hydroxide precursor TM-OH. <NUM> was obtained by filtration of the resulting suspension, washing with distilled water, drying at <NUM> in air and sieving.

<NUM> (base): The mixed transition metal hydroxide precursor TM-OH. <NUM> was mixed with Li-OH 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 a mixture of oxygen. After cooling to ambient temperature, the resultant powder was deagglomerated and sieved through a <NUM> mesh to obtain the base cathode active material B-CAM <NUM>.

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

<NUM>): A beaker was charged with <NUM> of de-ionized water. An amount of <NUM> B-CAM. <NUM> was added. The resultant slurry was stirred at ambient temperature over a period of <NUM> minutes, during said stirring the slurry temperature was maintained at <NUM>.

<NUM>): Then, the water was removed by filtration through a filter press. A wet filter cake remained.

<NUM>): The resultant filter cake was dried in vacuo at <NUM> for <NUM> hours and then at <NUM> over a period of <NUM> hours. A powder was obtained.

<NUM>): Then, by sieving the powder obtained from step (e. <NUM>) with a mesh <NUM> sieve, comparative cathode active material C-CAM. <NUM> was obtained.

<NUM>): The resultant filter cake was dried in vacuo at <NUM> for <NUM> hours and then at <NUM> over a period of <NUM> hours.

<NUM>): Then, <NUM> (<NUM> mol) boric acid were added and mixing was performed in a high speed mixer at <NUM> rpm. A mixture was obtained.

<NUM>): The resulting mixture was thermally treated at <NUM> for <NUM> hours in a muffle furnace and in a forced flow of oxygen. Then, by sieving the resultant powder with a mesh <NUM> sieve, comparative cathode active material C-CAM. <NUM> was obtained.

<NUM>): An amount of <NUM> B-CAM. <NUM> was slurried in de-ionized water (conductivity of water less than <NUM>/m) under constant stirring. An aqueous solution of <NUM> mol-% Al<NUM>(SO<NUM>)<NUM> (with respect to TM in B-CAM. <NUM>) was added. The total amount of de-ionized water used is <NUM>. The resultant slurry was stirred at ambient temperature over a period of <NUM> minutes.

<NUM>): The resulting mixture was thermally treated at <NUM> for <NUM> hours in a muffle furnace and in a forced flow of oxygen. Then, by sieving the resultant powder with a mesh <NUM> sieve, inventive cathode active material CAM. <NUM> was obtained.

<NUM>): An amount of <NUM> B-CAM. <NUM> was slurried in de-ionized water (conductivity less than <NUM>/m) under constant stirring. An aqueous solution of <NUM> mol-% Al<NUM>(SO<NUM>)<NUM> (with respect to TM in B-CAM. <NUM>) was added. The total amount of de-ionized water used was <NUM>. The resultant slurry was stirred at ambient temperature over a period of <NUM> minutes.

<NUM>): SiW<NUM> aq. was added to the wet filter cake from (c. The molar ratio of W/TM was <NUM>. The resultant mixture was transferred into a plastic bag and scrambled for <NUM> minutes at ambient temperature.

<NUM>): The resultant filter cake was dried in ultra-dry air at <NUM> for <NUM> hours and then at <NUM> over a period of <NUM> hours.

<NUM>): Then, <NUM> (<NUM> mol) boric acid were added and mixing was performed in accordance with (f. A mixture was obtained.

<NUM>): An amount of <NUM> B-CAM. <NUM> was slurried in de-ionized water (conductivity less than <NUM>/m) under constant stirring. A suspension of <NUM> mol-% Sb<NUM>O<NUM> (with respect to TM in B-CAM. <NUM>), was added to the slurry. The total amount of de-ionized water used was <NUM>. The resultant slurry was stirred at ambient temperature over a period of <NUM> minutes.

<NUM>): Then, <NUM> (<NUM> mol) boric acid (with respect to TM in B-CAM. <NUM>) were added and mixing was performed in accordance with (f. A mixture was obtained.

<NUM>): An amount of <NUM> B-CAM. <NUM> was slurried in de-ionized water (conductivity less than <NUM>/m) under constant stirring. A suspension of <NUM> mol-% Sb<NUM>O<NUM> (with respect to TM in B-CAM. <NUM>), was added to the slurry. The total amount of de-ionized water used is <NUM>. The resultant slurry was stirred at ambient temperature over a period of <NUM> minutes.

<NUM>): SiW<NUM> aq. was added to the wet filter cake from step (c. The molar ratio of W/TM was <NUM>. The resultant mixture was transferred into a plastic bag and scrambled for <NUM> minutes at ambient temperature.

<NUM>): Then, <NUM> (<NUM> mol) boric acid were added and mixing was performed in a highspeed mixer at <NUM> rpm. A mixture was obtained.

The protocols are summarized in Table <NUM>.

The results are summarized in Table <NUM>.

Positive electrode: PVDF binder (Solef® <NUM>) was dissolved in NMP (Merck) to produce a <NUM> wt. % solution. For electrode preparation, binder solution (<NUM> wt. %), and carbon black (Li250, <NUM> wt. -%) were suspended in NMP. After mixing using a planetary centrifugal mixer (ARE-<NUM>, Thinky Corp. ; Japan), either any of inventive CAM. <NUM> to CAM. <NUM> or a base cathode active material B-CAM. <NUM> or a comparative cathode active material, (<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 KTF-S roll-to-roll coater (Mathis AG). 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.

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 2wt. % 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 III. <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 (II. <NUM>) were introduced into the coin 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 II. <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. The results are summarized in Table <NUM>. For the cycling, the current density was <NUM> C and charge and discharge were repeated <NUM> times.

The cell reaction resistance growth was calculated by the following method:
After the <NUM> cycles under <NUM>. 1C, the coin cells are recharged to <NUM>. 3V, and the resistance is measured again by the electrochemical impedance spectroscopy (EIS) method. The ratio of the resistance value of <NUM>th cycle and second cycle is defined as the resistance growth. The results are summarized in Table <NUM>. [%] relative resistance growth is based on the resistance growth of cell based on C-CAM. <NUM> as <NUM>%.

Claim 1:
Process for the manufacture of a coated cathode active material comprising the steps of
(a) providing a particulate electrode active material according to general formula Li<NUM>+xTM<NUM>-xO<NUM>, wherein TM is Ni and, optionally, at least one of Co and Mn, and, optionally, at least one element selected from Al, Mg, and Ba, transition metals other than Ni, Co, and Mn, and x is in the range of from zero to <NUM>, wherein at least <NUM> mole-% of the transition metal of TM is Ni,
(b) treating said particulate electrode active material with an aqueous medium that may contain a heteropoly acid or a compound of Al or Sb,
(c) removing the water from step (b) at least partially,
(d) optionally, adding at least one heteropoly acid or its respective ammonium or lithium salt or a compound of Al or Sb, as particulate compound or as aqueous solution or slurry,
(e) optionally, treating the mixture from step (d) thermally,
(f) adding at least one compound selected from compounds of Al or Sb or B, or at least one heteropoly acid or its respective ammonium or lithium salt or salt of Al, Ga, In, or Ba to the solid material obtained from step (e), if applicable, or from step (d) or (c),
respectively, thereby depositing at least one element selected from on the surface of
said particulate electrode active material, wherein the element deposited in step (f) is different from the element deposited in step (b) or (d), respectively, and
(g) treating the residue obtained from step (f) thermally,
wherein either step (d) is performed or the aqueous medium in step (b) contains a heteropoly acid or a compound of Al or Sb, or both.