EP4658619A1 - Process for the preparation of overlithiated lithium metal oxides - Google Patents

Process for the preparation of overlithiated lithium metal oxides

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Publication number
EP4658619A1
EP4658619A1 EP23821633.7A EP23821633A EP4658619A1 EP 4658619 A1 EP4658619 A1 EP 4658619A1 EP 23821633 A EP23821633 A EP 23821633A EP 4658619 A1 EP4658619 A1 EP 4658619A1
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EP
European Patent Office
Prior art keywords
temperature
lithium
metal oxide
process according
mixture
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP23821633.7A
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German (de)
French (fr)
Inventor
Ulrich Wietelmann
Alexander HÜBNER
Johannes KLÖSENER
Katrin Wessels
Mary MAI
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Albemarle Germany GmbH
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Albemarle Germany GmbH
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Filing date
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Application filed by Albemarle Germany GmbH filed Critical Albemarle Germany GmbH
Publication of EP4658619A1 publication Critical patent/EP4658619A1/en
Pending legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G45/00—Compounds of manganese
    • C01G45/02—Oxides
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G49/00—Compounds of iron
    • C01G49/02—Oxides; Hydroxides
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G51/00—Compounds of cobalt
    • C01G51/40—Complex oxides containing cobalt and at least one other metal element
    • C01G51/42—Complex oxides containing cobalt and at least one other metal element containing alkali metals, e.g. LiCoO2
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G53/00—Compounds of nickel
    • C01G53/40—Complex oxides containing nickel and at least one other metal element
    • C01G53/42—Complex oxides containing nickel and at least one other metal element containing alkali metals, e.g. LiNiO2
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G53/00—Compounds of nickel
    • C01G53/40—Complex oxides containing nickel and at least one other metal element
    • C01G53/42—Complex oxides containing nickel and at least one other metal element containing alkali metals, e.g. LiNiO2
    • C01G53/44—Complex oxides containing nickel and at least one other metal element containing alkali metals, e.g. LiNiO2 containing manganese
    • 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
    • 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
    • H01M4/0471—Processes of manufacture in general involving thermal treatment, e.g. firing, sintering, backing particulate active material, thermal decomposition, pyrolysis
    • 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
    • H01M4/364—Composites as mixtures
    • 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
    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
    • 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
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/12—Surface area
    • 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
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes
    • 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 invention relates to an economical process for the preparation of overlithiated lithium metal oxides from lithium peroxide and at least one transition metal oxide, and to their use.
  • Overlithiated lithium metal oxides are used as cathode additives for the purpose of prelithiation for lithium ion batteries.
  • lithium ion batteries represent the upper limit of battery technologies currently available on an industrial scale. They are therefore being used to a rapidly increasing extent for both stationary and mobile galvanic energy storage systems. In particular, the increasing demands on range in mobile applications in automobiles or other transport technologies require ever higher energy densities. This trend requires the use of electrode materials with the highest possible capacities and electrode pairings that are capable of realizing the highest possible voltage.
  • Graphite-based materials with a theoretical capacity of 372 mAh/g are usually used as anode materials.
  • lithium-alloyable materials, especially Si-based powders are mixed with the graphite.
  • the usable energy content of lithium ion batteries is degraded by a series of decomposition and parasitic reactions.
  • the most important parasitic reaction for LIBs involves the loss of "active lithium” during negative electrode filming, i.e. , the formation of a "solid electrolyte layer, SEI" on the surface of the anode particles during the initial charge/discharge cycles.
  • SEI solid electrolyte layer
  • graphite anodes typically consume about 3- 5% of the total lithium introduced into a battery cell with the cathode material to form the SEI, which is stable during the rest of the process.
  • the lithium "consumed" by the protective layer formation i.e., converted to a form that is no longer electrochemically active, is missing in the further course of the cycle for the complete utilization and discharge of the cathode material.
  • the irreversible initial losses are even significantly higher when alloyable anode components such as Si or Sn-based powders are used: the Li losses can account for up to 20%, depending on their proportion in the anode material.
  • metallic lithium or various Li rich compounds can be added to the cathode and/or anode materials.
  • Such prelithiation agents provide their lithium inventory during the "formation" of the battery cell (i.e., the first charge/discharge cycles) and decompose to form volatile by-products or electrochemically predominatly inactive solids.
  • the activatable Li content must be as high as possible. This is the case for a number of so-called overlithiated lithium metal oxides.
  • Overlithiated metal oxides which can alternatively also be referred to as lithium-rich metal oxides, are those lithium-containing oxide compounds which have an increased lithium content compared with the LIB cathode materials used as standard and which can make this additional content available during the first charge/discharge cycle to compensate for irreversible lithium losses on the anode side. Since this process is irreversible, the overlithiated metal oxides are not recovered during subsequent cycles.
  • the transition metals M contained are present in a correspondingly reduced form compared with the corresponding LIB cathode material.
  • Overlithiated lithium metal oxides can release lithium from the structure when the battery is discharged (usually irreversibly), forming oxide compounds in which the contained redox active metals are oxidized accordingly.
  • Lis+xFeCM >0 to 3
  • Lii+xNiO2 >0 to 1
  • this compound formally absorbs additional oxygen during lithium absorption (F. Holtierie, Batteries 2018, 4, 4).
  • the preparation of the overlithiated metal compounds is usually carried out by reacting lithium base salts such as lithium hydroxide monohydrate, lithium carbonate or preferably lithium oxide with the corresponding transition metal hydroxide or transition metal oxide or a mixture of different transition metal hydroxides or oxides.
  • lithium base salts such as lithium hydroxide monohydrate, lithium carbonate or preferably lithium oxide
  • transition metal hydroxide or transition metal oxide or a mixture of different transition metal hydroxides or oxides.
  • lithium nickel oxide (LisN iOs) according to the state of the art (G. Cedar, Chem. Mater. 2004, 2685) is produced by reacting lithium oxide with nickel oxide in an inert (i.e. oxygen-free) atmosphere:
  • nickel oxide is first ground with lithium oxide in a ball mill, then pelletized and calcined under an inert argon atmosphere for 24 h at 650°C.
  • Overlithiated lithium cobalt oxide LieCoO4 is prepared by a solid/solid reaction by reacting CoO and U2O at 900°C under a nitrogen atmosphere (Yingying Zhou, Dissertation 2021 , https://doi.org/10.14989/doctor.k22548).
  • Li5FeO4 is prepared from U2O and FesO4 at 500 or 800°C under air atmosphere (M.V.BIanco et al., Chem. Eng. J. 354, 2018, 370-7) according to:
  • Overlithiated spinels such as Lin-xNio.5Mm.5O4 are prepared by reacting the corresponding normal cathode material LiNio.5Mm.5O4 with a lithium source at 600°C under reducing conditions (G. Gabrielli et al., J. Power Sources, 351 , 2017, 35).
  • Li2O Li2O
  • the disadvantage of these described processes is the use of Li2O, which can only be produced by very complex processes, for example by combustion of metallic lithium or by thermal decomposition of lithium carbonate at temperatures > 900°C or of mixtures of lithium carbonate and carbon black at > 700°C. Since lithium carbonate melts already at 720°C, the thermal decomposition of lithium carbonate usually yields solidified melts or at least strongly sintered products that have to be crushed and ground up in a complex process. This mechanical comminution and the subsequent screening require the exclusion of air components (H2O and CO2) that are reactive to lithium oxide, resulting in very high process costs.
  • H2O and CO2 air components
  • a method is desired that allows the synthesis of overlithiated lithium metal oxides, for example Li2NiO2, by a low-cost synthesis, preferably a one-pot synthesis, from Li2O2 and transition metal oxides, for example NiO.
  • the object is solved by a process characterized in that a) lithium peroxide Li2O2 is mixed with at least one transition metal oxide MaOb or a manganese-containing spinel compound and subsequently b) the mixture is calcined, where M in the transition metal oxide is selected from Fe, Ni, Co and Mn, a is a number from 1 to 3 and b is a number from 1 to 4, and the manganese-containing spinel compound is selected from LiMn2O4 and LiNio.5Mm.5O4 and the mixture is calcined successively at at least two successively different temperature levels, wherein in b) a first temperature level is in the range of 280 to 450°C and a second temperature level is in the range of 500 to 950°C.
  • M in the transition metal oxide is selected from Fe, Ni, Co and Mn
  • a is a number from 1 to 3
  • b is a number from 1 to 4
  • the manganese-containing spinel compound is selected from LiMn2
  • a mixture of powdered lithium peroxide and the at least one desired metal oxide or the manganese-containing spinel compound is mixed.
  • the mixing of the at least two components - lithium peroxide and at least one transition metal oxide or a manganese-containing spinel compound, respecitvely, - is preferably carried out under grinding conditions; the mixture obtained is then preferably compressed or pressed by applying an external pressure.
  • the mixture is then converted to the overlithiated lithium metal oxide by calcination in two process steps at two different temperature levels.
  • the calcination is preferably carried out in a one-pot process.
  • a lithium peroxide with a high specific surface area is preferably used.
  • the specific surface area is preferably at least 1 m 2 /g, particularly preferably at least 2 m 2 /g.
  • the first temperature is in the range of 300 to 400°C, and preferably, the second temperature is in the range of 600 to 900°C.
  • the calcination time at the first temperature is in the range of from 0.5 to 20 hours, more preferably from 1 to 10 hours, and most preferably from 2 hours to 10 hours.
  • the calcination duration at the second temperature is preferably in the range from 1 to 96 hours, preferably from 1 to 72 hours, more preferably from 2 to 72 hours, even more preferably from 2 to 48 hours.
  • lithium oxide U2O is formed with oxygen evolution, and the oxygen is pumped out of the system either in a vacuum or by overflowing with an inert gas (e.g. nitrogen or argon).
  • an inert gas e.g. nitrogen or argon
  • the formed lithium oxide L reacts with the at least one transition metal oxide or a manganese-containing spinel compound to form the overlithiated lithium metal oxide.
  • the calcining at the first and second temperatures is suitably carried out under vacuum or an inert gas atmosphere, the vacuum preferably being 1 to 10000 Pa (0.01 to 100 mbar), in particular 5 to 5000 Pa (0.05 to 50 mbar) and the inert gas atmosphere being formed by an inert gas or gas mixture excluding water/humidity and CO2, wherein the inert gas/mixture preferably comprises nitrogen, argon or helium, and wherein calcination at the second temperature is additionally carried out largely excluding oxygen.
  • the vacuum preferably being 1 to 10000 Pa (0.01 to 100 mbar), in particular 5 to 5000 Pa (0.05 to 50 mbar) and the inert gas atmosphere being formed by an inert gas or gas mixture excluding water/humidity and CO2, wherein the inert gas/mixture preferably comprises nitrogen, argon or helium, and wherein calcination at the second temperature is additionally carried out largely excluding oxygen.
  • the two calcination steps may be carried out at the different temperature levels preferably in the same reaction vessel, ensuring either by temporal and/or spatial separation measures the requirements for the different temperature and atmospheric conditions of the two reaction steps.
  • the decomposition of the lithium peroxide which takes place under oxygen evolution, does not cause undesired oxidation of the metal oxide or the manganese-containing spinel compound present in the mixture.
  • the transition metal-containing oxide compounds were found to be inert under the conditions of the first calcination temperature level of 280 to 450°C required for peroxide decomposition under evacuation conditions or under an inert gas stream (e.g., nitrogen). In this way, the desired overlithiated metal oxide compounds can be obtained in high purity in the second calcination step at elevated temperatures of at least 500 to 950°C.
  • calcination is carried out in corrosion-resistant and high- temperature-resistant vessels or reactors, the reactor construction materials being in particular high-temperature-resistant materials which are resistant to corrosion by basic lithium salts, preferably metallic materials selected from high-temperature- resistant Cr- and/or Al-containing materials (in particular Cr- and/or Al-containing nickel-base alloys, Ni- and Cr-containing austenitic steels, low-Ni or Ni-free, Cr- and Al-containing ferritic steels or chromium-containing mixed austenitic-ferritic steels), oxide ceramics (in particular AI2O3, lithium aluminate ceramics (UAIO2), Ce-based ceramics (in particular Ce-stabilized ZrC ), non-oxide ceramics (in particular carbides, preferably SiC, BC, TiC; Nitrides, preferably TiN, AIN; and Borides, preferably NbB2, BN, Al-infiltrated TiB 2 , "TiBAI").
  • the process according to the invention can be carried out under static conditions, wherein the mixture of transition metal oxide and Li2O2 in corrosion-resistant shells or as a bulk on a belt is first heated to a temperature in the range of 280 to 450°C under vacuum conditions or in an inert gas atmosphere, the thermal decomposition of the U2O2 taking place with oxygen evolution, and after completion of the U2O2 decomposition and removal of the oxygen formed from the system, the higher temperature necessary for the formation of the overlithiated metal oxide is set in the range of 500 to 950°C while ensuring an oxygen-free atmosphere.
  • the process according to the invention can be carried out under moving bed conditions in a reactor that ensures continuous mixing of the reaction mixture.
  • the reactor is preferably a continuously operated heatable rotating tube with at least two different temperature zones, wherein in the region of the inlet of the raw material mixture the temperature is 280 to 450°C, while the temperature in the rear region, which is closer to the region for product discharge, the temperature is 500 to 950°C, wherein in the region of the temperature of 500 to 950°C suitable conditions are set for the formation of the overlithiated lithum metal oxide by overflowing with an inert gas or an inert gas mixture which is substantially free of O2, CO2 and H2O.
  • the inert gas or gas mixture is preferably passed countercurrently to the direction of motion of the solid reaction mixture.
  • the mixing of lithium peroxide and the at least one transition metal oxide can be carried out either in rotating mixers with an energy input in the range of about 10 to 500 kW/m 3 or in a mill, in particular an impact rotor mill (impact mill), grinding media mill or pin mill.
  • the subsequent preferred compaction takes place, for example, in the course of a tabletting process, i.e. by exerting pressure by means of a movable die on the powder mixture located in a die, or with the aid of a rolling mill, i.e. by means of two rollers rotating against each other, or by means of powder presses.
  • the pressing pressure is 0.001 to 100 kbar, preferably 0.01 to 50 kbar.
  • the transition metal oxide used in the process according to the invention is preferably selected from NiO, CoO Fe2Os, FesCM and FeO.
  • the overlithiated lithium metal oxide is Li2NiO2 and the mixing molar ratio Li2O2:NiO is 1 :1.
  • overlithiated metal oxide compounds prepared by the method according to the invention can be used for prelithiation in the production of lithium ion batteries.
  • the preferably powdered lithium peroxide Li2O2 and the transition metal oxide(s) MaOb are first mixed.
  • Rotating mixers are particularly suitable, providing an energy input in the range of about 10 to 500 kW/m 3 .
  • the rotating mixers both those with rotating vessels and those with rotating mixing tools are suitable. What is important is a sufficiently strong energy input.
  • Such units which can be designed according to the counterflow or crossflow principle, are offered, for example, by the Eirich company under the designation "intensive mixer”.
  • Other suitable mixer designs are paddle dryers with additionally installed knife mills, as offered for example by the company Lbdige, and intensive mixers with highspeed rotors, which are available for example from the company Hosokawa under the brand name "Nobilta”.
  • mills are also suitable for intensive mixing, especially beater rotor mills (impact mills), grinding media mills or pin mills; knife or cutter mills can also be used to a limited extent.
  • grinding media mills mixing is carried out in grinding drums using hard grinding media, such as balls, rods and the like consisting of metals (steels or nickel-based alloys) or hard ceramics (metal oxides, metal carbides, metal nitrides, etc).
  • the Vickers hardness of the grinding vessels and grinding media is at least 400, preferably at least 600. Materials made of stainless steels or metal oxides, for example aluminum oxide or zirconium oxide, are particularly preferred. Ball, rod or hammer mills can be used.
  • uniaxial powder presses can be used, which are available from Frey & Co, for example. On a smaller scale, simple punch/die systems are preferred.
  • axial powder presses with servo-motor, mechanical or hydraulic compression are suitable, for example, as offered by Dorst Technologies.
  • the subsequent thermally induced conversion takes place at two different temperature levels and in different atmospheres.
  • the low temperature step in the range of 280 to 450°C, preferably 300 to 400°C, especially 320 to 380°C, only the lithium peroxide in the mixture is converted to lithium oxide:
  • the evolved oxygen is removed from the reactor system either by an evacuation process, i.e. under constant reduced pressure (dynamic reduced pressure), or by a carrier gas stream consisting of a gas mixture free of H 2 O and CO 2 .
  • Suitable carrier gas streams are inert gases (N 2 , Ar, He in commercially available qualities) or dry, CO 2 -free air.
  • the mixture consisting of an approximately equimolar mixture of lithium oxide and nickel oxide is calcined at higher temperatures, forming the desired overlithiated nickel oxide in a solid/solid reaction:
  • the mixture of transition metal oxide and L12O2 is first heated to a temperature of 280 to 450°C in corrosion-resistant trays or as a bulk on a conveyor belt, where thermal decomposition of the peroxide takes place with O2 evolution.
  • This first reaction stage requires either vacuum conditions or an inert gas atmosphere, i.e., a gas or gas mixture that is non-reactive to the reactants and products (free of H2O and CO2).
  • the temperature is raised to the temperature of 500 to 950°C necessary to produce the overlithiated lithium transition metal oxide, and this reaction step is also carried out under vacuum conditions or an oxygen-free inert gas atmosphere (i.e., a gas atmosphere that is H2O, CO2, and 02-free).
  • Suitable inert gases include nitrogen and noble gases such as argon or helium.
  • This variant is preferably carried out continuously in a reactor that ensures mixing.
  • This reactor is preferably a rotating tube with two different temperature zones: in the region of the inlet of the raw material mixture, the temperature is 280 to 450°C, while the temperature in the rear region, i.e. the region closer to the product outlet, has a temperature level that enables the synthesis reaction between the lithium oxide formed in the first zone and the at least one transition metal oxide to produce the desired overlithiated lithium metal oxide. This is in the case of the synthesis of Li2NiO2 a temperature in the range of 550 to 950°C.
  • a reducing (i.e., oxygen-free) atmosphere be established in the high-temperature zone. This is ensured by passing an oxygen-free inert gas stream over the reaction mixture in the countercurrent direction (i.e., in the opposite direction to the direction of motion of the moving bed of solids).
  • the two calcination steps are carried out in equipment whose product-facing surfaces are made of materials resistant to high temperatures and corrosion from basic lithium salts.
  • a wide range of metallic materials selected from high-temperature resistant Cr- and/or Al-containing materials can be used for this purpose.
  • Cr- and/or Al-containing nickel-base alloys, Ni and Cr-containing austenitic steels as well as low- Ni or Ni-free, Cr- and Al-containing ferritic steels and chromium-containing mixed austenitic-ferritic steels can be used as container materials.
  • the chromium content of the alloys suitable for use is at least 15 wt.%, preferably at least 20 wt.% and particularly preferably at least 30 wt.%.
  • the chromium content can be selected to be significantly lower (at least 5 wt.%).
  • the preferred Al content is at least 1 wt.%, particularly preferably at least 2 wt.%.
  • the metallic material alloys which can be used for the process according to the invention can contain the elements niobium, titanium, tantalum and/or silicon, in each case in proportions of up to 10 wt.%.
  • low- Mo alloys are used.
  • the Mo content is below ⁇ 2 wt.%, preferably ⁇ 1 wt.%.
  • Ni-based alloys Inconel 600, Inconel 601 , Inconel 693, Inconel 702, Inconel 800, Inconel 825; Incoloy 901 , Nichrome, Nichrome V, Nimonic 75, Nimonic 80A, Nimonic 90, RA602CA/Alloy 602 CA, Alloy X and comparable grades;
  • Austenitic steels SS347 (1.4550), 253MA (1.4835), Nitronic 50, 310S, 316L, SS310, SS304, RA253MA and similar;
  • Kanthal e.g. Kanthal A1 , Kanthal AF, Kanthal D (FeCrAI)
  • PM 2000 Incoloy MA 956 and similar.
  • the corrosion-inhibiting coating on the product-facing side contains at least 10% by weight, preferably at least 30% by weight, of chromium. Furthermore, it may contain the elements Ni, Fe, Nb, Al, Ti, Ta and Si in contents of max. 10 wt.% each.
  • the thickness of the chromium-containing, corrosion-preventive coating is at least 5 pm, preferably at least 10 pm.
  • the coating thickness is determined by electron microscopy.
  • an only moderately corrosion-resistant austenitic steel such as 1 .4401 can be significantly improved in terms of its corrosion resistance by applying a 50 pm thick Cr- and Al-containing coating.
  • Such a coating process can be accomplished via various electrochemical or physical technologies, for example a pack-cementation process (Kim, Mater. Transact. 43, 2002, 593).
  • certain oxide ceramics e.g., AI2O3, lithium aluminate ceramics (UAIO2), or Ce-based ceramics, e.g., Ce-stabilized ZrO2
  • non-oxide ceramics e.g., carbides such as SiC, BC, TiC; nitrides such as TiN, AIN; and borides such as NbBs, BN, Al-infiltrated TiB , "TiBAI
  • Materials coated with the above-mentioned ceramics preferably LiAIO?) , for example high-temperature resistant steels, can also be used.
  • Carbon-based materials such as material graphites (carbon graphites, hard carbons) and pure carbons with a disordered graphite structure and ceramic properties (glass carbons) can be used to a limited extent.
  • high-temperature calcination processes i.e. processes at temperatures > approx. 400°C
  • oxidizing agents such as oxygen or other oxygen donors such as water or CO2. Since oxygen is released in the first reaction substep, a certain amount of burnup is hardly avoidable over longer periods of time. Therefore, oxidation-stabilized graphite materials are preferred, which show significantly lower burnup rates than high-purity graphite when in contact with ambient air.
  • Graphite materials are high-temperature resistant materials produced via a filler/binder system from raw materials such as petroleum cokes, pitch cokes, carbon blacks, and graphites. They are first ground to defined particle size distributions, mixed at elevated temperature, formed and compacted into green bodies in presses, and then carbonized by a high-temperature pyrolysis process.
  • the carbon-based materials can be used as solid reaction vessels, or hollow bodies coated or lined with graphitic material (e.g., metal tubes lined with graphite foil) can be used.
  • graphitic material e.g., metal tubes lined with graphite foil
  • the overlithiated metal oxide compounds produced according to the invention are mixed with cathode materials for lithium ion batteries for the purpose of prelithiation and processed to form positive electrode strips.
  • the overlithiated metal oxide compounds decompose in the first chargedischarge cycles to release lithium.
  • the tablet was then calcined in an aluminum oxide crucible in a tube furnace under a light nitrogen flow (20 L/h).
  • the heated, nitrogen-fluxed furnace tube was made of quartz glass. Initially, it was heated to 300°C and held at this temperature for 2 h. The furnace temperature was then increased. Then, the furnace temperature was increased to 700°C within about 30 min and held at this temperature for 24 h.
  • the crucible After cooling to RT, the crucible was placed in a glove box with air excluded. The tablet had not disintegrated and had taken on a black color.
  • the tablet was then calcined in an aluminum oxide crucible in a tubular furnace under a light nitrogen stream.
  • the heated, nitrogen flow furnace tube was made of quartz glass. Initially, it was heated to 300°C and held at this temperature for 2 h. The furnace temperature was increased to 700°C. Then, the furnace temperature was increased to 700°C and held at this temperature for 24 h.
  • the crucible After cooling to RT, the crucible was placed in a glove box with air excluded. The tablet had not disintegrated and had taken on a black coloration.
  • a further increase in the degree of conversion can be achieved by optimizing the experimental conditions, in particular by extending the calcination time.

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Abstract

The invention relates to a process for the preparation of overlithiated transition metal oxides, for example Li2NiO2, from a mixture consisting of lithium peroxide and at least one transition metal oxide or a manganese-containing spinel compound in a two-stage calcination process with respect to temperature and atmospheric composition.

Description

Process for the preparation of overlithiated lithium metal oxides
The invention relates to an economical process for the preparation of overlithiated lithium metal oxides from lithium peroxide and at least one transition metal oxide, and to their use. Overlithiated lithium metal oxides are used as cathode additives for the purpose of prelithiation for lithium ion batteries.
Background
In terms of energy density, lithium ion batteries represent the upper limit of battery technologies currently available on an industrial scale. They are therefore being used to a rapidly increasing extent for both stationary and mobile galvanic energy storage systems. In particular, the increasing demands on range in mobile applications in automobiles or other transport technologies require ever higher energy densities. This trend requires the use of electrode materials with the highest possible capacities and electrode pairings that are capable of realizing the highest possible voltage.
Modern high power lithium batteries contain high voltage cathode materials, mainly nickel rich materials Li(NixMnyCoz)O2 (with x + y + z = 1 and Ni >0.33) or high voltage spinel compounds such as LiMm.5Nio.5O4. Graphite-based materials with a theoretical capacity of 372 mAh/g are usually used as anode materials. To increase this capacity, lithium-alloyable materials, especially Si-based powders, are mixed with the graphite.
The usable energy content of lithium ion batteries (LIBs) is degraded by a series of decomposition and parasitic reactions. The most important parasitic reaction for LIBs involves the loss of "active lithium" during negative electrode filming, i.e. , the formation of a "solid electrolyte layer, SEI" on the surface of the anode particles during the initial charge/discharge cycles. It is known that graphite anodes typically consume about 3- 5% of the total lithium introduced into a battery cell with the cathode material to form the SEI, which is stable during the rest of the process. The lithium "consumed" by the protective layer formation, i.e., converted to a form that is no longer electrochemically active, is missing in the further course of the cycle for the complete utilization and discharge of the cathode material.
The irreversible initial losses are even significantly higher when alloyable anode components such as Si or Sn-based powders are used: the Li losses can account for up to 20%, depending on their proportion in the anode material.
To compensate for these losses, metallic lithium or various Li rich compounds can be added to the cathode and/or anode materials. Such prelithiation agents provide their lithium inventory during the "formation" of the battery cell (i.e., the first charge/discharge cycles) and decompose to form volatile by-products or electrochemically predominatly inactive solids. To keep this proportion of inactive solids as low as possible, the activatable Li content must be as high as possible. This is the case for a number of so-called overlithiated lithium metal oxides. Overlithiated metal oxides, which can alternatively also be referred to as lithium-rich metal oxides, are those lithium-containing oxide compounds which have an increased lithium content compared with the LIB cathode materials used as standard and which can make this additional content available during the first charge/discharge cycle to compensate for irreversible lithium losses on the anode side. Since this process is irreversible, the overlithiated metal oxides are not recovered during subsequent cycles.
To balance the charge, the transition metals M contained are present in a correspondingly reduced form compared with the corresponding LIB cathode material.
This is explained in the following table:
Overlithiated lithium metal oxides can release lithium from the structure when the battery is discharged (usually irreversibly), forming oxide compounds in which the contained redox active metals are oxidized accordingly.
The table above lists the final stages of overlithiation. Starting from the "normal" cathode materials, there are all intermediate stages between the "normal form" and the overlithiated form with respect to the lithium content. These are formally formed by lithium uptake of the base material, mostly under reducing conditions, i.e., in nonoxidizing atmospheres. For the purposes of the invention, all of the above LIB cathode materials with a lithium content in excess of normal lithiation are considered "overlithiated" (see also US-A-6 652 605). Overlithiated metal oxides, unlike LIB cathode materials, are generally not stable in air and water, i.e., they must be handled under inert gas to avoid undesirable changes. These are then the following compositions: Lis+xFeCM (x = >0 to 3); Lii+xNiO2 (x = >0 to 1 ); Lii+xCoOi.5+o.5x (x = > 0 to 5); overlithiated Spinell compounds Lii+xMn2O4 (x = >0 to 1 ); Lin-xNio.5Mn1.5O4 (x = >0 to 1). In the case of LieCoO4, this compound formally absorbs additional oxygen during lithium absorption (F. Holtstiege, Batteries 2018, 4, 4).
The preparation of the overlithiated metal compounds is usually carried out by reacting lithium base salts such as lithium hydroxide monohydrate, lithium carbonate or preferably lithium oxide with the corresponding transition metal hydroxide or transition metal oxide or a mixture of different transition metal hydroxides or oxides.
For example, prior art overlithiated lithium nickel oxide (LisN iOs) according to the state of the art (G. Cedar, Chem. Mater. 2004, 2685) is produced by reacting lithium oxide with nickel oxide in an inert (i.e. oxygen-free) atmosphere:
1. ball mill
NiO + Li2o - ► Li2NiO2
2. 650°C/24 h-Ar
For this purpose, nickel oxide is first ground with lithium oxide in a ball mill, then pelletized and calcined under an inert argon atmosphere for 24 h at 650°C. Overlithiated lithium cobalt oxide LieCoO4 is prepared by a solid/solid reaction by reacting CoO and U2O at 900°C under a nitrogen atmosphere (Yingying Zhou, Dissertation 2021 , https://doi.org/10.14989/doctor.k22548). Li5FeO4 is prepared from U2O and FesO4 at 500 or 800°C under air atmosphere (M.V.BIanco et al., Chem. Eng. J. 354, 2018, 370-7) according to:
FesO4 + 7.5 Li2O + 0.5 O2 — > 3 LisFeO4 or synthesized from a ground mixture of Fe2Os and U2O by heating first to 450°C, then 750°C under inert conditions (W.M. Dose et al., J. Electrochem. Soc. 2020, 167 160543).
Overlithiated spinels such as Lin-xNio.5Mm.5O4 are prepared by reacting the corresponding normal cathode material LiNio.5Mm.5O4 with a lithium source at 600°C under reducing conditions (G. Gabrielli et al., J. Power Sources, 351 , 2017, 35).
The disadvantage of these described processes is the use of Li2O, which can only be produced by very complex processes, for example by combustion of metallic lithium or by thermal decomposition of lithium carbonate at temperatures > 900°C or of mixtures of lithium carbonate and carbon black at > 700°C. Since lithium carbonate melts already at 720°C, the thermal decomposition of lithium carbonate usually yields solidified melts or at least strongly sintered products that have to be crushed and ground up in a complex process. This mechanical comminution and the subsequent screening require the exclusion of air components (H2O and CO2) that are reactive to lithium oxide, resulting in very high process costs.
In contrast, U2O production by thermal decomposition of lithium peroxide, U2O2, requires only relatively low temperatures of about 300 - 400°C, conditions well below melting point conditions. Consequently, thermal decomposition produces, according to:
200 - 400 °C . .
U2O2 1/2 O2 directly, a finely divided, flowable Li2O powder is formed, which is excellently suited for the production of, for example, Li2NiO2 (J. Kim et al., Molecules 2019, 24, 4624).
The disadvantage of this production process is that the Li2O produced from U2O2 must be isolated as such and this must then be mixed with NiO or another transition metal oxide or hydroxide in separate reaction steps and then thermolyzed (KR101887171 B1 ).
Object to be solved
A method is desired that allows the synthesis of overlithiated lithium metal oxides, for example Li2NiO2, by a low-cost synthesis, preferably a one-pot synthesis, from Li2O2 and transition metal oxides, for example NiO.
Description of the invention
According to the invention, the object is solved by a process characterized in that a) lithium peroxide Li2O2 is mixed with at least one transition metal oxide MaOb or a manganese-containing spinel compound and subsequently b) the mixture is calcined, where M in the transition metal oxide is selected from Fe, Ni, Co and Mn, a is a number from 1 to 3 and b is a number from 1 to 4, and the manganese-containing spinel compound is selected from LiMn2O4 and LiNio.5Mm.5O4 and the mixture is calcined successively at at least two successively different temperature levels, wherein in b) a first temperature level is in the range of 280 to 450°C and a second temperature level is in the range of 500 to 950°C. In this process, a mixture of powdered lithium peroxide and the at least one desired metal oxide or the manganese-containing spinel compound is mixed. The mixing of the at least two components - lithium peroxide and at least one transition metal oxide or a manganese-containing spinel compound, respecitvely, - is preferably carried out under grinding conditions; the mixture obtained is then preferably compressed or pressed by applying an external pressure.
The mixture is then converted to the overlithiated lithium metal oxide by calcination in two process steps at two different temperature levels. The calcination is preferably carried out in a one-pot process.
A lithium peroxide with a high specific surface area is preferably used. The specific surface area is preferably at least 1 m2/g, particularly preferably at least 2 m2/g.
Preferably, the first temperature is in the range of 300 to 400°C, and preferably, the second temperature is in the range of 600 to 900°C.
Preferably, the calcination time at the first temperature is in the range of from 0.5 to 20 hours, more preferably from 1 to 10 hours, and most preferably from 2 hours to 10 hours.
Independently thereof, the calcination duration at the second temperature is preferably in the range from 1 to 96 hours, preferably from 1 to 72 hours, more preferably from 2 to 72 hours, even more preferably from 2 to 48 hours.
During calcination at the first temperature, lithium oxide U2O is formed with oxygen evolution, and the oxygen is pumped out of the system either in a vacuum or by overflowing with an inert gas (e.g. nitrogen or argon).
During calcination at the second temperature, the formed lithium oxide L reacts with the at least one transition metal oxide or a manganese-containing spinel compound to form the overlithiated lithium metal oxide.
The calcining at the first and second temperatures is suitably carried out under vacuum or an inert gas atmosphere, the vacuum preferably being 1 to 10000 Pa (0.01 to 100 mbar), in particular 5 to 5000 Pa (0.05 to 50 mbar) and the inert gas atmosphere being formed by an inert gas or gas mixture excluding water/humidity and CO2, wherein the inert gas/mixture preferably comprises nitrogen, argon or helium, and wherein calcination at the second temperature is additionally carried out largely excluding oxygen.
The two calcination steps may be carried out at the different temperature levels preferably in the same reaction vessel, ensuring either by temporal and/or spatial separation measures the requirements for the different temperature and atmospheric conditions of the two reaction steps.
Surprisingly, it was found that the decomposition of the lithium peroxide, which takes place under oxygen evolution, does not cause undesired oxidation of the metal oxide or the manganese-containing spinel compound present in the mixture. Thus, the transition metal-containing oxide compounds were found to be inert under the conditions of the first calcination temperature level of 280 to 450°C required for peroxide decomposition under evacuation conditions or under an inert gas stream (e.g., nitrogen). In this way, the desired overlithiated metal oxide compounds can be obtained in high purity in the second calcination step at elevated temperatures of at least 500 to 950°C.
According to the invention, calcination is carried out in corrosion-resistant and high- temperature-resistant vessels or reactors, the reactor construction materials being in particular high-temperature-resistant materials which are resistant to corrosion by basic lithium salts, preferably metallic materials selected from high-temperature- resistant Cr- and/or Al-containing materials (in particular Cr- and/or Al-containing nickel-base alloys, Ni- and Cr-containing austenitic steels, low-Ni or Ni-free, Cr- and Al-containing ferritic steels or chromium-containing mixed austenitic-ferritic steels), oxide ceramics (in particular AI2O3, lithium aluminate ceramics (UAIO2), Ce-based ceramics (in particular Ce-stabilized ZrC ), non-oxide ceramics (in particular carbides, preferably SiC, BC, TiC; Nitrides, preferably TiN, AIN; and Borides, preferably NbB2, BN, Al-infiltrated TiB2, "TiBAI").
The process according to the invention can be carried out under static conditions, wherein the mixture of transition metal oxide and Li2O2 in corrosion-resistant shells or as a bulk on a belt is first heated to a temperature in the range of 280 to 450°C under vacuum conditions or in an inert gas atmosphere, the thermal decomposition of the U2O2 taking place with oxygen evolution, and after completion of the U2O2 decomposition and removal of the oxygen formed from the system, the higher temperature necessary for the formation of the overlithiated metal oxide is set in the range of 500 to 950°C while ensuring an oxygen-free atmosphere.
Alternatively, the process according to the invention can be carried out under moving bed conditions in a reactor that ensures continuous mixing of the reaction mixture. In this case, the reactor is preferably a continuously operated heatable rotating tube with at least two different temperature zones, wherein in the region of the inlet of the raw material mixture the temperature is 280 to 450°C, while the temperature in the rear region, which is closer to the region for product discharge, the temperature is 500 to 950°C, wherein in the region of the temperature of 500 to 950°C suitable conditions are set for the formation of the overlithiated lithum metal oxide by overflowing with an inert gas or an inert gas mixture which is substantially free of O2, CO2 and H2O. In this process, the inert gas or gas mixture is preferably passed countercurrently to the direction of motion of the solid reaction mixture.
The mixing of lithium peroxide and the at least one transition metal oxide can be carried out either in rotating mixers with an energy input in the range of about 10 to 500 kW/m3 or in a mill, in particular an impact rotor mill (impact mill), grinding media mill or pin mill.
The subsequent preferred compaction takes place, for example, in the course of a tabletting process, i.e. by exerting pressure by means of a movable die on the powder mixture located in a die, or with the aid of a rolling mill, i.e. by means of two rollers rotating against each other, or by means of powder presses. The pressing pressure is 0.001 to 100 kbar, preferably 0.01 to 50 kbar.
The transition metal oxide used in the process according to the invention is preferably selected from NiO, CoO Fe2Os, FesCM and FeO.
The mixing molar ratio of U2O2 to the transition metal oxide in the process according to the invention is usually in the range of 0.6:1 to 3:1 , preferably 0.9:1 to 3:1 , and in the case of M = Ni is in particular 1 :1. For example, the preferred ratio for Fe = 5:1 , for Ni = 2:1 , for Co = 6:1.
The overlithiated lithium metal oxide prepared according to the invention is preferably Li5FeO4, Li2NiO2, LieCoC , or an overlithiated manganese-containing spinel compound, in particular Lii+xMn2O4 or Lh+xNio.sMni.sC , where x = >0 to 1.
Particularly preferably, the overlithiated lithium metal oxide is Li2NiO2 and the mixing molar ratio Li2O2:NiO is 1 :1.
The overlithiated metal oxide compounds prepared by the method according to the invention can be used for prelithiation in the production of lithium ion batteries.
The process according to the invention is carried out as explained in more detail below.
To realize the process according to the invention, the preferably powdered lithium peroxide Li2O2 and the transition metal oxide(s) MaOb are first mixed. For the mixing process, different equipment and process technologies can be applied. Rotating mixers are particularly suitable, providing an energy input in the range of about 10 to 500 kW/m3. Among the rotating mixers, both those with rotating vessels and those with rotating mixing tools are suitable. What is important is a sufficiently strong energy input. Such units, which can be designed according to the counterflow or crossflow principle, are offered, for example, by the Eirich company under the designation "intensive mixer". Other suitable mixer designs are paddle dryers with additionally installed knife mills, as offered for example by the company Lbdige, and intensive mixers with highspeed rotors, which are available for example from the company Hosokawa under the brand name "Nobilta".
Most types of mills are also suitable for intensive mixing, especially beater rotor mills (impact mills), grinding media mills or pin mills; knife or cutter mills can also be used to a limited extent. In grinding media mills, mixing is carried out in grinding drums using hard grinding media, such as balls, rods and the like consisting of metals (steels or nickel-based alloys) or hard ceramics (metal oxides, metal carbides, metal nitrides, etc). The Vickers hardness of the grinding vessels and grinding media is at least 400, preferably at least 600. Materials made of stainless steels or metal oxides, for example aluminum oxide or zirconium oxide, are particularly preferred. Ball, rod or hammer mills can be used.
For the subsequent compaction, uniaxial powder presses can be used, which are available from Frey & Co, for example. On a smaller scale, simple punch/die systems are preferred. For the processing of larger powder quantities, axial powder presses with servo-motor, mechanical or hydraulic compression are suitable, for example, as offered by Dorst Technologies.
The subsequent thermally induced conversion (the calcination) takes place at two different temperature levels and in different atmospheres.
This is explained with the example of the production of overlithiated Li nickel oxide.
In the first step, the low temperature step in the range of 280 to 450°C, preferably 300 to 400°C, especially 320 to 380°C, only the lithium peroxide in the mixture is converted to lithium oxide:
The evolved oxygen is removed from the reactor system either by an evacuation process, i.e. under constant reduced pressure (dynamic reduced pressure), or by a carrier gas stream consisting of a gas mixture free of H2O and CO2. Suitable carrier gas streams are inert gases (N2, Ar, He in commercially available qualities) or dry, CO2-free air.
In the second step, the mixture consisting of an approximately equimolar mixture of lithium oxide and nickel oxide is calcined at higher temperatures, forming the desired overlithiated nickel oxide in a solid/solid reaction:
Li2O/NiO - Li2NiO2 This second reaction step requires higher temperatures of 550 to 750°C, preferably 600 to 700°C, with this reaction step also taking place under vacuum conditions or an inert gas atmosphere, whereby this gas atmosphere, in contrast to the first calcination phase, should additionally be oxygen-free (i.e. a gas atmosphere that is H2O, CO2 and 02-free is ensured). Suitable inert gases are, for example, nitrogen as well as noble gases such as argon or helium.According to the invention, two different process variants are conceivable in the production of the overlithiated metal oxides:
1 . Static process:
The mixture of transition metal oxide and L12O2 is first heated to a temperature of 280 to 450°C in corrosion-resistant trays or as a bulk on a conveyor belt, where thermal decomposition of the peroxide takes place with O2 evolution. This first reaction stage requires either vacuum conditions or an inert gas atmosphere, i.e., a gas or gas mixture that is non-reactive to the reactants and products (free of H2O and CO2).
After completion of the O2 gas evolution, the temperature is raised to the temperature of 500 to 950°C necessary to produce the overlithiated lithium transition metal oxide, and this reaction step is also carried out under vacuum conditions or an oxygen-free inert gas atmosphere (i.e., a gas atmosphere that is H2O, CO2, and 02-free). Suitable inert gases include nitrogen and noble gases such as argon or helium.
2. Moving bed process:
This variant is preferably carried out continuously in a reactor that ensures mixing. This reactor is preferably a rotating tube with two different temperature zones: in the region of the inlet of the raw material mixture, the temperature is 280 to 450°C, while the temperature in the rear region, i.e. the region closer to the product outlet, has a temperature level that enables the synthesis reaction between the lithium oxide formed in the first zone and the at least one transition metal oxide to produce the desired overlithiated lithium metal oxide. This is in the case of the synthesis of Li2NiO2 a temperature in the range of 550 to 950°C. To avoid undesired oxidation of the transition metal oxide used at this higher temperature level (for example, from Ni(ll) to Ni(lll) or Ni(IV)), it is necessary that a reducing (i.e., oxygen-free) atmosphere be established in the high-temperature zone. This is ensured by passing an oxygen-free inert gas stream over the reaction mixture in the countercurrent direction (i.e., in the opposite direction to the direction of motion of the moving bed of solids).
The two calcination steps are carried out in equipment whose product-facing surfaces are made of materials resistant to high temperatures and corrosion from basic lithium salts. A wide range of metallic materials selected from high-temperature resistant Cr- and/or Al-containing materials can be used for this purpose. In particular, Cr- and/or Al-containing nickel-base alloys, Ni and Cr-containing austenitic steels as well as low- Ni or Ni-free, Cr- and Al-containing ferritic steels and chromium-containing mixed austenitic-ferritic steels can be used as container materials. The chromium content of the alloys suitable for use is at least 15 wt.%, preferably at least 20 wt.% and particularly preferably at least 30 wt.%. In the case of Al contents of at least 1 wt.%, the chromium content can be selected to be significantly lower (at least 5 wt.%). The preferred Al content is at least 1 wt.%, particularly preferably at least 2 wt.%. In addition to chromium and aluminum, the metallic material alloys which can be used for the process according to the invention can contain the elements niobium, titanium, tantalum and/or silicon, in each case in proportions of up to 10 wt.%. Preferably, low- Mo alloys are used. The Mo content is below < 2 wt.%, preferably < 1 wt.%.
The following commercially available metallic materials are particularly advantageous for use:
Ni-based alloys: Inconel 600, Inconel 601 , Inconel 693, Inconel 702, Inconel 800, Inconel 825; Incoloy 901 , Nichrome, Nichrome V, Nimonic 75, Nimonic 80A, Nimonic 90, RA602CA/Alloy 602 CA, Alloy X and comparable grades;
Austenitic steels: SS347 (1.4550), 253MA (1.4835), Nitronic 50, 310S, 316L, SS310, SS304, RA253MA and similar;
Ferritic steels: Kanthal (e.g. Kanthal A1 , Kanthal AF, Kanthal D (FeCrAI)), PM 2000, Incoloy MA 956 and similar.
Both solid metallic materials selected from the above-mentioned groups of materials and appropriately coated high-temperature resistant black or stainless steels can be used. The corrosion-inhibiting coating on the product-facing side contains at least 10% by weight, preferably at least 30% by weight, of chromium. Furthermore, it may contain the elements Ni, Fe, Nb, Al, Ti, Ta and Si in contents of max. 10 wt.% each.
The thickness of the chromium-containing, corrosion-preventive coating is at least 5 pm, preferably at least 10 pm. The coating thickness is determined by electron microscopy. For example, an only moderately corrosion-resistant austenitic steel such as 1 .4401 can be significantly improved in terms of its corrosion resistance by applying a 50 pm thick Cr- and Al-containing coating. Such a coating process can be accomplished via various electrochemical or physical technologies, for example a pack-cementation process (Kim, Mater. Transact. 43, 2002, 593).
In addition to the metallic materials mentioned above, certain oxide ceramics (e.g., AI2O3, lithium aluminate ceramics (UAIO2), or Ce-based ceramics, e.g., Ce-stabilized ZrO2) and non-oxide ceramics (e.g., carbides such as SiC, BC, TiC; nitrides such as TiN, AIN; and borides such as NbBs, BN, Al-infiltrated TiB , "TiBAI") can also be used as container materials. Materials coated with the above-mentioned ceramics (preferably LiAIO?) , for example high-temperature resistant steels, can also be used.
Carbon-based materials such as material graphites (carbon graphites, hard carbons) and pure carbons with a disordered graphite structure and ceramic properties (glass carbons) can be used to a limited extent. However, the use of carbon-based materials in high-temperature calcination processes, i.e. processes at temperatures > approx. 400°C, requires particularly strictly controlled inert conditions, i.e. the complete exclusion of oxidizing agents such as oxygen or other oxygen donors such as water or CO2. Since oxygen is released in the first reaction substep, a certain amount of burnup is hardly avoidable over longer periods of time. Therefore, oxidation-stabilized graphite materials are preferred, which show significantly lower burnup rates than high-purity graphite when in contact with ambient air. (D.V. Savchenko, New Carbon Materials 2012, 27, 12-18), are used. Graphite materials are high-temperature resistant materials produced via a filler/binder system from raw materials such as petroleum cokes, pitch cokes, carbon blacks, and graphites. They are first ground to defined particle size distributions, mixed at elevated temperature, formed and compacted into green bodies in presses, and then carbonized by a high-temperature pyrolysis process.
The carbon-based materials can be used as solid reaction vessels, or hollow bodies coated or lined with graphitic material (e.g., metal tubes lined with graphite foil) can be used.
The overlithiated metal oxide compounds produced according to the invention are mixed with cathode materials for lithium ion batteries for the purpose of prelithiation and processed to form positive electrode strips. As a component of the positive electrode, the overlithiated metal oxide compounds decompose in the first chargedischarge cycles to release lithium.
Examples
General:
All manipulations of the lithium raw materials (lithium peroxide as well as lithium oxide) were carried out under inert conditions, i.e. in an Ar-filled glove box.
The characterization of the reaction products was done by powder diffraction (XRD). An instrument from Bruker (AXS D2 Phaser A26) is used. The determination of the specific surface area of the lithium compounds used was carried out by gas adsorption according to the method of Stephen Brunauer, Paul Hugh Emmett and Edward Teller ("BET").
Example 1
Production of LiaNiC from NiO and IJ2O2
In an Ar-filled glove box, 1 .90 g (41 .4 mmol) of lithium peroxide (97%, BET = 7.6 m2/g, supplier Albemarle Germany) and 3.09 g (41.4 mmol) of nickel (II) oxide (NiO green, catalogue No. SIAL399523-100G from Sigma Aldrich) were mixed in an agate mortar and pre-milled and then ground together in a Fritsch planetary ball mill (Pulverisette 7, in Easy GTM grinding bowls made of ZrO2). For grinding the approx. 5 g powder mixture, 12 ZrO2 balls with a diameter of 10 mm were used; the grinding time was 2 hours at 600 upm. A brownish mixture was obtained, from which the balls were removed by sieving.
1 .0 g of the ground mixture was filled into a die set from Specac and compressed into a tablet for 15 minutes with a contact pressure of 500 kg (corresponding to approx. 620 bar).
The tablet was then calcined in an aluminum oxide crucible in a tube furnace under a light nitrogen flow (20 L/h). The heated, nitrogen-fluxed furnace tube was made of quartz glass. Initially, it was heated to 300°C and held at this temperature for 2 h. The furnace temperature was then increased. Then, the furnace temperature was increased to 700°C within about 30 min and held at this temperature for 24 h.
After cooling to RT, the crucible was placed in a glove box with air excluded. The tablet had not disintegrated and had taken on a black color.
Yield: 0.87 g (weight loss 13.1 %, corresponding to 99 % of theory).
XRD: Mixture of Li2NiO2, 23 wt.%; NiO, 51 wt.%; l_i2O, 26 wt.%.
Example 2 (comparative example)
Preparation of Li2NiO2 from NiO and LiaO
In an Ar-filled glove box, 1.429 g (47.8 mmol) lithium oxide (99%, BET = 2.4 m2/g, supplier Albemarle Germany) and 3.571 g (47.8 mmol) nickel (II) oxide (NiO green, catalog no. SIAL399523-100G from Sigma-Aldrich) were mixed and pre-milled in an agate mortar and then ground together in a Fritsch planetary ball mill (Pulverisette 7, in Easy GTM grinding bowls made of ZrOa). 12 ZrO2 balls with a diameter of 10 mm were used to grind the approx. 5 g powder mixture; the grinding time was 2 hours at 600 upm. A brown-gray mixture was obtained, from which the balls were removed by sieving.
1.0 g of the ground mixture was filled into a die set from Specac and compressed into a tablet for 15 minutes with a contact pressure of 500 kg (corresponding to approx. 620 bar).
The tablet was then calcined in an aluminum oxide crucible in a tubular furnace under a light nitrogen stream. The heated, nitrogen flow furnace tube was made of quartz glass. Initially, it was heated to 300°C and held at this temperature for 2 h. The furnace temperature was increased to 700°C. Then, the furnace temperature was increased to 700°C and held at this temperature for 24 h.
After cooling to RT, the crucible was placed in a glove box with air excluded. The tablet had not disintegrated and had taken on a black coloration.
Yield: 1.0 g (no significant weight loss).
XRD: mixture of L 2N iC>2, 11 wt%; NiO, 60 wt%; IJ2O, 29 wt%.
The experiments demonstrate that with the process control according to the invention, using U2O2, the desired Li2NiO2 is formed without the oxygen produced during the first calcination step changing the oxidation number of the NiO used. Surprisingly, the conversion when U2O2 is used is more than twice as high as observed when Li2O is used.
A further increase in the degree of conversion can be achieved by optimizing the experimental conditions, in particular by extending the calcination time.

Claims

Claims
1 . A process for the preparation of overlithiated lithium metal oxides by reaction of lithium peroxide with at least one transition metal oxide or a manganese- containing spinel compound, characterized in that a) lithium peroxide U2O2 is mixed with at least one transition metal oxide MaOb or a manganese-containing spinel compound and subsequently b) the mixture is calcined, wherein
M in the transition metal oxide is selected from Fe, Ni, Co and Mn and the manganese-containing spinel compound is selected from LiMn2O4 and LiNio.5Mm.5O4 and a is a number from 1 to 3 and b is a number from 1 to 4, and the mixture is successively calcined at at least two successively different temperature levels, wherein in b) a first temperature level is in the range from 280 to 450°C and a second temperature level is in the range from 500 to 950°C.
2. The process according to claim 1 , characterized in that the first temperature is preferably in the range from 300 to 400°C and the second temperature is preferably in the range from 600 to 900°C, wherein the calcination time at the first temperature is preferably in the range from 0.5 to 20 hours, in particular from 1 to 10 hours, and wherein the calcination time at the second temperature is independently preferably in the range from 1 to 96 hours, preferably from 1 to 72 hours, more preferably from 2 to 72 hours, even more preferably from 2 to 48 hours.
3. The process according to any one of claims 1 or 2, characterized in that the calcining at the first and second temperatures is carried out under vacuum or an inert gas atmosphere, wherein the vacuum is preferably 1 to 10000 Pa (0.01 to 100 mbar), in particular 5 to 5000 Pa (0.05 to 50 mbar) and the inert gas atmosphere is formed by an inert gas or an inert gas mixture with exclusion of water/humidity and CO2, wherein the inert gas/mixture of gases preferably comprises nitrogen, argon or helium, and wherein calcination at the second temperature is additionally carried out with exclusion of oxygen.
4. The process according to any one of claims 1 to 3, characterized in that the two calcination steps are carried out at the different temperature levels in the same reaction vessel, the requirements for the different temperature and atmospheric conditions of the two reaction steps being ensured either by temporal or spatial separation measures.
5. A process according to any one of claims 1 to 4, characterized in that a lithium peroxide having a specific surface area of min. 1 m2/g, preferably min. 2 m2/g, is used.
6. The process according to any one of claims 1 to 5, characterized in that the calcining is carried out in corrosion-resistant and high-temperature-resistant reactors, the reactor construction materials being, in particular, high- temperature-resistant materials which are corrosion-resistant to basic lithium salts, preferably metallic materials selected from high-temperature-resistant Cr- and/or Al-containing materials (in particular Cr- and/or Al-containing nickel-base alloys, Ni- and Cr-containing austenitic steels, low-Ni or Ni-free, Cr- and Al- containing ferritic steels or chromium-containing mixed austenitic-ferritic steels), oxide ceramics (in particular AI2O3, lithium aluminate ceramics (UAIO2), Ce- based ceramics (in particular Ce-stabilized Zrt ), non-oxide ceramics (in particular carbides, preferably SiC, BC, TiC; Nitrides, preferably TiN, AIN; and Borides, preferably NbB2, BN, Al-infiltrated TiB2, "TiBAI").
7. The process according to any one of claims 1 to 6, characterized in that it is carried out under static conditions, wherein the mixture of transition metal oxide and LJ2O2 in corrosion-resistant shells or as a bulk on a belt is first heated to a temperature of 280 to 450°C under vacuum conditions or in an inert gas atmosphere, wherein the thermal decomposition of the U2O2 takes place with oxygen evolution, and after completion of the LJ2O2 decomposition, the higher temperatures of 500 to 950°C necessary for the formation of the overlithiated metal oxide are adjusted while ensuring an oxygen-free atmosphere.
8. The process according to any one of claims 1 to 6, characterized in that it is carried out under moving bed conditions in a reactor ensuring continuous mixing of the reaction mixture.
9. The process according to claim 8, characterized in that the reactor is preferably a continuously operated heatable rotary tube with at least two different temperature zones, wherein in the region of the inlet of the raw material mixture the temperature is 280 - 450°C, while in the rear region, which is closer to the area for product discharge, the temperature is 500 - 950°C, wherein in the area of the temperature of 500 - 950°C suitable conditions are set for the formation of the overlithiated lithum metal oxide by overflowing with an inert gas or an inert gas mixture which is substantially free of O2, CO2 and H2O.
10. The process according to any one of claims 1 to 9, characterized in that the mixing of lithium peroxide and the at least one transition metal oxide is carried out either in rotating mixers with an energy input in the range of about 10 to 500 kW/m3 or in a mill, in particular an impact rotor mill (impact mill), grinding media mill or pin mill.
11. A process according to any one of claims 1 to 10, characterized in that the mixture consisting of lithium peroxide and at least one transition metal oxide or a manganese-containing spinel compound is compressed prior to calcination using contact pressures in the range between 0.001 to 100 kbar, preferably 0.01 to 50 kbar.
12. The process according to one of claims 1 to 11 , characterized in that the transition metal oxide is selected from nickel, manganese, cobalt or iron oxides, preferably NiO, CoO Fe2Os, FesC and FeO, particularly preferably NiO, CoO and Fe2Os.
13. The process according to any one of claims 1 to 12, characterized in that the mixing molar ratio of U2O2 to the transition metal oxide is in the range of 0.6 : 1 to 3 : 1. preferably 0.9 : 1 to 3 : 1 , and for M = Ni is in particular 1 :1.
14. The process according to any one of claims 1 to 13, characterized in that the overlithiated lithium metal oxide is Li2+xFeO4 (x = >0 to 3); Lii+xNiCh (x = >0 to 1 ); Lii+xCoOi.5+o.5x (x = >0 to 5); Lii+xMn2O4 (x = >0 to 1); Lin-xNio.5Mm.5O4 (x = >0 to 1), preferably Li5FeO4, Li2NiO2, LieCoO4, Li2Mn2O4 or Li2Nio.5Mm.5O4, wherein preferably the overlithiated lithium metal oxide is Li2NiO2 and the mixing molar ratio Li2O2:NiO is 1 :1.
15. Use of the overlithiated metal oxide compounds produced by the process according to any one of claims 1 to 14 for prelithiation in the production of lithium ion batteries.
EP23821633.7A 2023-02-02 2023-12-11 Process for the preparation of overlithiated lithium metal oxides Pending EP4658619A1 (en)

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FR2777386B1 (en) 1998-04-14 2000-05-12 Commissariat Energie Atomique PROCESS FOR THE PREPARATION OF LITHIA OR SURLITHIA TRANSITION METAL OXIDE, POSITIVE ELECTRODE ACTIVE MATERIAL INCLUDING THIS OXIDE, AND ACCUMULATOR
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