Method for preparing over-lithiated lithium metal oxide

Abstract

The invention relates to a method for producing an over-lithiated transition metal oxide, for example Li2NiO2, from a mixture of lithium peroxide and at least one transition metal oxide or manganese-containing spinel compound in a two-stage calcination process involving temperature and atmosphere composition.

Description

[0001] The present invention relates to an economical process for preparing perlithiated lithium metal oxides from lithium peroxide and at least one transition metal oxide and uses of the perlithiated lithium metal oxides. The perlithiated lithium metal oxides are used as cathode additives for pre-lithiation of lithium-ion batteries. Background Art

[0002] Lithium-ion batteries represent the upper limit of current industrial-scale battery technology in terms of energy density. Consequently, their use in stationary and mobile energy storage systems is rapidly increasing. In particular, the growing demand for longer driving ranges in mobile applications, such as automobiles and other transportation technologies, demands ever-higher energy density. This trend necessitates the use of electrode materials with the highest possible capacity and electrode pairs capable of achieving the highest possible voltages.

[0003] Modern high-power lithium batteries contain high-voltage cathode materials, mainly nickel-rich materials Li (Ni x Mn y Co z )O2 (where x+y+z=1 and Ni>0.33) or high voltage spinel compounds such as LiMn 1.5 Ni 0.5 O4. Graphite-based materials with a theoretical capacity of 372 mAh / g are commonly used as negative electrode materials. To increase capacity, lithium alloy materials, especially silicon-based powders, are mixed with graphite.

[0004] The available energy of lithium-ion batteries (LIBs) is reduced by a series of decomposition and parasitic reactions. The most important parasitic reaction in LIBs is the loss of "active lithium" during the anode film formation process, that is, the formation of a "solid electrolyte layer, SEI" on the surface of the anode particles during the initial charge and discharge cycles. It is well known that graphite anodes typically consume about 3-5% of the total lithium introduced into the battery along with the cathode material to form the SEI film, which remains stable during the remaining cycles. The lithium "consumed" in the formation of the protective layer, that is, converted into a form that is no longer electrochemically active, is lost in the subsequent process of cycling, resulting in the complete utilization and discharge of the cathode material.

[0005] When alloy anode components are used (e.g., silicon- or tin-based powders), the irreversible initial losses are even higher: lithium losses can be as high as 20%, depending on their proportion in the anode material.

[0006] To compensate for these losses, metallic lithium or various Li-rich compounds can be added to the positive and / or negative electrode materials. Such pre-lithiation agents provide a lithium inventory during the battery's "formation" (i.e., the first charge / discharge cycle) and decompose to form volatile by-products or solids that are mainly electrochemically inactive. In order to keep the proportion of inactive solids as low as possible, the content of activatable Li must be as high as possible. This is the case with many so-called overlithiated lithium metal oxides. Overlithiated metal oxides, which can also be called lithium-rich metal oxides, are lithium-containing oxides that have a higher lithium content than standard LIB positive electrode materials. They can use this additional lithium content to compensate for the irreversible lithium losses on the negative electrode side during the first charge and discharge cycle. Since this process is irreversible, the overlithiated metal oxides cannot be recovered in subsequent cycles.

[0007] To balance the charge, the transition metal M is present in a corresponding reduced form compared to the corresponding LIB cathode material.

[0008] The following table explains this:

[0009]

[0010] Overlithiated lithium metal oxides release lithium from their structure during battery discharge (usually irreversibly), forming oxide compounds in which the redox-active metals they contain are correspondingly oxidized.

[0011] The table above lists the final stages of overlithiation. Starting from a "normal" cathode material, there are all intermediate stages between the "normal form" and the overlithiated form in terms of lithium content. These intermediate stages are formed chemically by the absorption of lithium by the matrix material, mainly under reducing conditions (i.e. in a non-oxidizing atmosphere). For the purposes of the present invention, all the above-mentioned LIB cathode materials with a lithium content exceeding that of normal lithiation are considered to be "overlithiated" (see also US-A-6 652 605). Unlike LIB cathode materials, overlithiated metal oxides are generally unstable in air and water and must therefore be handled under inert gas to avoid undesirable changes.

[0012] Its composition is as follows: Li 2+x FeO4 (x=>0 to 3); Li 1+x NiO2 (x=>0 to 1); Li 1+x CoO 1.5+0.5x (x=>0 to 5); Overlithiated spinel compound Li 1+x Mn2O4 (x=>0 to 1); Li 1+x Ni 0.5 Mn 1.5O4 (x=>0 to 1). For Li6CoO4, this compound chemically absorbs additional oxygen during the absorption of lithium (F. Holtstiege, Batteries 2018, 4, 4).

[0013] The preparation of the perlithiated metal compounds is generally carried out by reacting a lithium alkali salt (for example lithium hydroxide, 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.

[0014] For example, according to the prior art (G. Cedar, Chem. Mater. 2004, 2685), prior art overlithiated lithium nickel oxide (Li2NiO2) is produced by reacting lithium oxide with nickel oxide in an inert (i.e., oxygen-free) atmosphere:

[0015]

[0016] To this end, nickel oxide and lithium oxide are first ground in a ball mill, then granulated and calcined at 650°C for 24 hours under an inert argon atmosphere. Overlithiated lithium cobalt oxide Li6CoO4 is prepared by a solid / solid reaction, that is, CoO and Li2O react at 900°C under a nitrogen atmosphere (Yingying Zhou, dissertation 2021, https: / / doi.org / 10.14989 / doctor.k22548). Li5FeO4 is prepared from Li2O and Fe3O4 at 500 or 800°C in an air atmosphere (MV Blanco et al., Chem. Eng. J. 354, 2018, 370-7) according to the following:

[0017] Fe3O4+7.5Li2O+0.5O2→3Li5FeO4

[0018] Or it can be synthesized from a ground mixture of Fe2O3 and Li2O under inert conditions by first heating to 450°C and then heating to 750°C (WM Dose et al., J. Electrochem. Soc. 2020, 167 160543).

[0019] Fe2O3+5Li2O→2Li5FeO4

[0020] Overlithiated spinels, such as Li 1+x Ni 0.5 Mn 1.5 O4 is obtained by reducing the corresponding normal cathode material LiNi 0.5 Mn 1.5Prepared by reacting O4 with a lithium source at 600°C (G. Gabrielli et al., J. Power Sources, 351, 2017, 35).

[0021] A disadvantage of these described processes is the use of Li2O, a material that can only be prepared through very complex processes, such as combustion of metallic lithium or thermal decomposition of lithium carbonate at temperatures >900°C or thermal decomposition of mixtures of lithium carbonate and carbon black at temperatures >700°C. Since lithium carbonate is molten at 720°C, thermal decomposition of lithium carbonate usually results in a solidified melt or at least a strongly sintered product that must be comminuted and ground in a complex process. This mechanical comminution and subsequent screening require the removal of air components (H2O and CO2) that react with the lithium oxide, resulting in very high process costs.

[0022] In contrast, the production of Li2O by thermal decomposition of lithium peroxide Li2O2 requires only relatively low temperatures of about 300-400°C, which is well below the melting point. Therefore, thermal decomposition is based on:

[0023]

[0024] Directly forms a finely divided, flowable Li2O powder, which is very suitable for producing, for example, Li2NiO2 (J. Kim et al., Molecules 2019, 24, 4624).

[0025] A disadvantage of this production process is that the Li2O generated from Li2O2 has to be separated as is and then has to be mixed with NiO or other transition metal oxides or hydroxides in a separate reaction step and then pyrolyzed (KR101887171B1).

[0026] Goals to be addressed

[0027] A method is desired that can synthesize perlithiated lithium metal oxides (such as Li2NiO2) from Li2O2 and transition metal oxides (such as NiO) by a low-cost synthesis (preferably a one-pot synthesis). DETAILED DESCRIPTION

[0028] According to the invention, this object is achieved by the following process, which is characterized in that

[0029] a) lithium peroxide Li2O2 and at least one transition metal oxide M a O b or mixed with manganese spinel compounds, followed by

[0030] b) calcining the mixture,

[0031] Wherein, M in the transition metal oxide is selected from Fe, Ni, Co and Mn, a is a number between 1 and 3, b is a number between 1 and 4, and the manganese-containing spinel compound is selected from LiMn2O4 and LiNi 0.5 Mn 1.5 O4

[0032] and calcining the mixture successively at at least two successively different temperature levels,

[0033] Wherein, in b), the first temperature level is in the range of 280 to 450°C, and the second temperature level is in the range of 500 to 950°C.

[0034] In this process, a mixture of powdered lithium peroxide and at least one desired metal oxide or manganese-containing spinel compound is mixed. The at least two components—lithium peroxide and at least one transition metal oxide or manganese-containing spinel compound—are preferably mixed under grinding conditions; the resulting mixture is then compressed or pressed, preferably by applying external pressure.

[0035] The mixture is then converted into 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.

[0036] 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 2m 2 / g.

[0037] 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.

[0038] Preferably, the calcination time at the first temperature is in the range of 0.5 to 20 hours, more preferably 1 to 10 hours, and most preferably 2 to 10 hours.

[0039] Independently, the duration of calcination at the second temperature is preferably 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.

[0040] During calcination at the first temperature, lithium oxide Li2O is generated and accompanied by the release of oxygen, which is evacuated from the system by means of vacuum or overflow with an inert gas (eg, nitrogen or argon).

[0041] During the calcination at the second temperature, the formed lithium oxide Li2O reacts with the at least one transition metal oxide or the manganese-containing spinel compound to form an over-lithiated lithium metal oxide.

[0042] The calcination at the first and second temperatures is preferably carried out under vacuum or in an inert gas atmosphere, preferably with a vacuum of 1 to 10,000 Pa (0.01 to 100 mbar), in particular 5 to 5,000 Pa (0.05 to 50 mbar), the inert gas atmosphere being formed by an inert gas or gas mixture free of water / moisture and CO 2 , wherein the inert gas / mixture preferably comprises nitrogen, argon or helium, and wherein the calcination at the second temperature is additionally carried out with the substantial exclusion of oxygen.

[0043] The two calcination steps can be carried out in the same reaction vessel at different temperature levels, with the requirements of the two reaction steps for different temperature and atmosphere conditions being ensured by temporal and / or spatial separation measures.

[0044] Surprisingly, we have found that the decomposition of lithium peroxide (performed under oxygen evolution) does not lead to undesirable oxidation of the metal oxide or manganese-containing spinel compound in the mixture. Thus, we have found that the transition metal-containing oxide compound exhibits inertness at the first calcination temperature (280 to 450° C.) required for peroxide decomposition under vacuum conditions or under an inert gas flow (e.g., nitrogen). Thus, the desired perlithiated metal oxide compound can be obtained in high purity by performing the second calcination step at an elevated temperature of at least 500 to 950° C.

[0045] According to the present invention, calcination is carried out in a corrosion-resistant and high-temperature resistant container or reactor, and the manufacturing material of the reactor is especially a high-temperature resistant material resistant to alkaline lithium salt corrosion, preferably a metal material, which is selected from high-temperature resistant Cr and / or Al-containing materials (especially nickel-based alloys containing Cr and / or Al, austenitic steels containing Ni and Cr, low-Ni or Ni-free ferritic steels containing Cr and Al, or chromium-containing mixed austenitic-ferritic steels), oxide ceramics (especially Al2O3), lithium aluminate ceramics (LiAlO2), Ce-based ceramics (especially Ce-stabilized ZrO2), non-oxide ceramics (especially carbides, preferably SiC, BC, TiC; nitrides, preferably TiN, AlN; and borides, preferably NbB2, BN, Al-infiltrated TiB2, "TiBAl").

[0046] The method according to the invention can be carried out under static conditions, wherein a mixture of transition metal oxide and Li2O2 in a corrosion-resistant housing or as bulk material on a belt is first heated to a temperature of 280 to 450° C. under vacuum conditions or in an inert gas atmosphere, the thermal decomposition of Li2O2 is accompanied by the release of oxygen, and after the decomposition of Li2O2 is complete and the oxygen formed is removed from the system, the higher temperature required for the formation of the overlithiated metal oxide is set in the range of 500 to 950° C., while ensuring an oxygen-free atmosphere.

[0047] 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 having at least two different temperature zones, wherein the temperature in the inlet zone of the feed mixture is 280 to 450°C, and in the rear zone near the product discharge zone is 500 to 950°C. In the temperature zone of 500 to 950°C, appropriate conditions are set to form a perlithiated lithium metal oxide by overflowing an inert gas or an inert gas mixture (the inert gas or inert gas mixture being substantially free of O2, CO2, and H2O). In this process, the inert gas or gas mixture is preferably passed countercurrent to the direction of movement of the solid reaction mixture.

[0048] The lithium peroxide and at least one transition metal oxide may be heated at an energy input ranging from about 10 to 500 kW / m 3 The mixing can be carried out in a rotary mixer or in a mill, in particular an impact rotor mill (impact mill), a grinding media mill or a pin mill.

[0049] The subsequent pressing is preferably carried out, for example, in a tableting process, i.e. by applying pressure to the powder mixture in a movable die, or by means of a rolling mill, i.e. by two rollers rotating relative to each other, or by means of a powder press. The pressing pressure is 0.001 to 100 kbar, preferably 0.01 to 50 kbar.

[0050] The transition metal oxide used in the process of the present invention is preferably selected from NiO, CoO, Fe2O3, Fe3O4 and FeO.

[0051] In the process according to the invention, the molar mixing ratio of Li2O2 to the transition metal oxide is generally in the range of 0.6:1 to 3:1, preferably in the range of 0.9:1 to 3:1, and in particular in the case of M=Ni, 1:1. For example, preferred ratios are Fe=5:1, Ni=2:1, and Co=6:1.

[0052] The over-lithiated lithium metal oxide prepared according to the present invention is preferably Li5FeO4, Li2NiO2, Li6CoO4, or an over-lithiated manganese-containing spinel compound, especially Li 1+x Mn2O4 or Li 1+x Ni 0.5 Mn 1.5 O4, where x=>0 to 1.

[0053] Particularly preferably, the over-lithiated lithium metal oxide is Li2NiO2, and the mixing molar ratio of Li2O2:NiO is 1:1.

[0054] The overlithiated metal oxide compound prepared according to the method of the present invention can be used for pre-lithiation in the production of lithium-ion batteries.

[0055] The process according to the invention is carried out as explained in more detail below.

[0056] In order to realize the method according to the present invention, it is preferred to firstly mix powdered lithium peroxide Li2O2 and transition metal oxide M a O b Mixing. For the mixing process, different equipment and process technologies can be applied. Rotary mixers are particularly suitable and can provide approximately 10 to 500 kW / m 3 The energy input is within the range of 100 MW. Among rotary mixers, both mixers with a rotating container and mixers with rotating mixing tools are suitable. The important thing is a sufficiently strong energy input. Such devices are designed according to the countercurrent or crosscurrent principle and are offered, for example, by the company Eirich under the name "intensive mixer". Another suitable mixer design is a paddle dryer with an additional knife mill, such as that provided by The company offers, and intensive mixers with high-speed rotors, which are offered, for example, by the company Hosokawa under the brand "Nobilta".

[0057] Most types of mills are also suitable for intense mixing, in particular agitator rotor mills (impact mills), grinding media mills or pin mills; knife mills or cutting mills can also be used to a limited extent. In grinding media mills, mixing is carried out in the grinding drum using hard grinding media, such as balls, rods, etc., made of metal (steel or nickel-based alloys) or hard ceramics (metal oxides, metal carbides, metal nitrides, etc.). The Vickers hardness of the grinding container and the grinding media is at least 400, preferably at least 600. Materials made of stainless steel or metal oxides (such as aluminum oxide or zirconium oxide) are particularly preferred. Ball mills, rod mills or hammer mills can be used.

[0058] For subsequent compaction, a uniaxial powder press can be used, such as those available from Frey & Co. On a smaller scale, a simple punch / die system is preferred. For processing large quantities of powder, an axial powder press equipped with a servo motor, mechanical or hydraulic compression is suitable, such as those offered by Dorst Technologies.

[0059] The subsequent thermally induced conversion (calcination) was carried out at two different temperature levels and in different atmospheres.

[0060] The production of over-lithiated Li nickel oxide is taken as an example for explanation.

[0061] In the first step, the temperature range of the low temperature step is 280 to 450°C, preferably 300 to 400°C, especially 320 to 380°C, and only lithium peroxide in the mixture is converted to lithium oxide:

[0062] Li2O2 / NiO→Li2O / NiO+ 1 / 2O2.

[0063] The released oxygen is removed from the reactor system by evacuation (i.e., under constant reduced pressure (dynamic reduced pressure)) or by a carrier gas flow consisting of a gas mixture that is free of H2O and CO2. Suitable carrier gas flows are inert gases (N2, Ar, He, commercial quality) or dry, CO2-free air.

[0064] In the second step, a mixture of approximately equimolar lithium oxide and nickel oxide is calcined at a higher temperature to form the desired overlithiated nickel oxide via a solid / solid reaction:

[0065] Li2O / NiO→Li2NiO2

[0066] This second reaction step requires a higher temperature of 550 to 750° C., preferably 600 to 700° C., and is also carried out under vacuum conditions or in an inert gas atmosphere, wherein, compared to the first calcination, the gas atmosphere should additionally be oxygen-free (i.e., it should be ensured that the gas atmosphere is free of H 2 O, CO 2 and O 2 ). Suitable inert gases are, for example, nitrogen and noble gases such as argon or helium. According to the present invention, two different process variants are conceivable for the production of perlithiated metal oxides:

[0067] 1. Static method:

[0068] First, a mixture of transition metal oxides and Li2O2 is heated to 280 to 450°C in corrosion-resistant trays or as bulk material on a conveyor belt. This is where the peroxide undergoes thermal decomposition, releasing O2. This first reaction stage requires vacuum conditions or an inert gas atmosphere, i.e., a gas or gas mixture that is unreactive towards the reactants and products (without H2O and CO2).

[0069] After the O2 gas release is complete, the temperature is raised to 500 to 950°C required to produce the over-lithiated lithium transition metal oxide. This reaction step is also carried out under vacuum conditions or an oxygen-free inert gas atmosphere (i.e., a gas atmosphere free of H2O, CO2, and O2). Suitable inert gases include nitrogen and noble gases such as argon or helium.

[0070] 2. Moving bed method:

[0071] This variant is preferably carried out continuously in a reactor that ensures mixing. The reactor is preferably a rotating tube with two distinct temperature zones: the inlet zone for the raw material mixture has a temperature of 280 to 450°C; and the rear zone (i.e., the zone near the product outlet) has a temperature that allows the lithium oxide formed in the first zone to undergo a synthesis reaction with at least one transition metal oxide, thereby producing the desired perlithiated lithium metal oxide. This is the case for the synthesis of Li2NiO2 at a temperature range of 550 to 950°C. To prevent undesirable oxidation of the transition metal oxide used at higher temperatures (e.g., from Ni(II) to Ni(III) or Ni(IV)), it is necessary to establish a reducing (i.e., oxygen-free) atmosphere in the high-temperature zone. This is achieved by introducing an oxygen-free inert gas flow in a countercurrent direction (i.e., opposite to the direction of motion of the moving bed solids).

[0072] Both calcining steps are carried out in an apparatus whose surface facing the product is made of a material resistant to high temperatures and corrosion by alkaline lithium salts. For this purpose, a variety of metal materials selected from high-temperature resistant materials containing Cr and / or Al can be used. In particular, nickel-based alloys containing Cr and / or Al, austenitic steels containing Ni and Cr, and low-Ni or Ni-free ferritic steels containing Cr and Al, and chromium-containing austenitic-ferritic mixed steels can be used as container materials. The chromium content of the applicable alloy is at least 15 wt.%, preferably at least 20 wt.%, and particularly preferably at least 30 wt.%. When the Al content is at least 1 wt.%, the chromium content can be selected to be much 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 metal material alloy that can be used in the method of the present invention can also contain the elements niobium, titanium, tantalum and / or silicon, with the proportion in each case reaching 10 wt.%. Low Mo alloys are preferably used. The Mo content is lower than <2 wt.%, preferably <1 wt.%.

[0073] The following commercially available metal materials are particularly advantageous for use:

[0074] Nickel-based alloys: Inconel 600, Inconel 601, Inconel 693, Inconel 702, Inconel 800, Inconel 825; Incoloy 901, Nichrome, Nichrome V, Nimonic 75, Nimonic 80A, Nimonic90, RA602CA / Alloy 602CA, Alloy X and comparable grades;

[0075] Austenitic steels: SS347 (1.4550), 253MA (1.4835), Nitronic 50, 310S, 316L, SS310, SS304, RA253MA and similar;

[0076] Ferritic steel: Kanthal (e.g., Kanthal A1, Kanthal AF, Kanthal D (FeCrAl)), PM2000, Incoloy MA956, etc.

[0077] Solid metal materials selected from the above-mentioned group of materials, as well as suitably coated high-temperature-resistant black steel or stainless steel, can be used. The anti-corrosion coating on the product-facing side contains at least 10% by weight, preferably at least 30% by weight, of chromium. Furthermore, it may contain Ni, Fe, Nb, Al, Ti, Ta, and Si in amounts of up to 10% by weight each.

[0078] The thickness of the chromium-containing anti-corrosion coating is at least 5 μm, preferably at least 10 μm. The coating thickness is determined by electron microscopy. For example, a 50 μm thick coating containing Cr and Al can significantly improve the corrosion resistance of austenitic steels (e.g., 1.4401) that have only moderate corrosion resistance. This coating process can be achieved using various electrochemical or physical techniques, such as the embedding process (Kim, Mater. Transact. 43, 2002, 593).

[0079] In addition to the aforementioned metal materials, certain oxide ceramics (e.g., Al2O3, lithium aluminate ceramics (LiAlO2), or cerium-based ceramics such as cerium-stabilized ZrO2) and non-oxide ceramics (e.g., carbides such as SiC, BC, and TiC; nitrides such as TiN and AlN; and borides such as NbB2, BN, Al-infused TiB2, or "TiBAl") can also be used as container materials. Materials coated with the aforementioned ceramics (preferably LiAlO2), such as high-temperature-resistant steel, can also be used.

[0080] Carbon-based materials, such as graphite (carbon graphite, hard carbon) and pure carbon with a disordered graphite structure and ceramic properties (glassy carbon), can be used to a limited extent. However, the use of carbon-based materials in high-temperature calcination processes (i.e., processes with temperatures > about 400°C) requires particularly strictly controlled inert conditions, i.e., the complete exclusion of oxidants, such as oxygen or other oxygen donors, such as water or CO2. Since oxygen is released in the first reaction sub-step, a certain amount of burn-up is almost unavoidable over a long period of time. Therefore, it is preferred to use oxidatively stable graphite materials, which have a significantly lower burn-up rate when in contact with ambient air than high-purity graphite. (DV Savchenko, New Carbon Materials 2012, 27, 12-18). Graphite materials are high-temperature resistant materials made from raw materials such as petroleum coke, pitch coke, carbon black, and graphite through a filler / binder system. They are first ground to a specified particle size distribution, mixed at high temperature, formed and pressed into green compacts in a press, and then carbonized by a high-temperature pyrolysis process.

[0081] Carbon-based materials can be used as solid reaction vessels, and hollow bodies coated or lined with graphite materials (e.g., metal tubes lined with graphite foil) can also be used.

[0082] The superlithiated metal oxide compound prepared according to the present invention is mixed with a lithium-ion battery cathode material for pre-lithiation and processed into a cathode strip. As a component of the cathode, the superlithiated metal oxide compound decomposes and releases lithium during the first charge and discharge cycle.

[0083] Example

[0084] Overview:

[0085] All operations with lithium raw materials (lithium peroxide and lithium oxide) were carried out under inert conditions, that is, in a glove box filled with argon.

[0086] The reaction products were characterized by powder diffraction (XRD) using a Bruker (AXS D2 Phaser A26) instrument.

[0087] The specific surface area of ​​the lithium compounds used was determined by gas adsorption according to the method of Stephen Brunauer, Paul Hugh Emmett and Edward Teller (“BET”).

[0088] Example 1

[0089] Li2NiO2 is produced from NiO and Li2O2

[0090] In a glove box filled with argon, 1.90 g (41.4 mmol) of lithium peroxide (97%, BET = 7.6 m 2 / g, supplier: Albemarle, Germany) and 3.09 g (41.4 mmol) of nickel(II) oxide (NiO green, catalog number SIAL399523-100G) were mixed and pre-ground in an agate mortar and then ground together in a Fritsch planetary ball mill (Pulverisette 7, in an Easy G™ grinding bowl made of ZrO). Twelve ZrO balls with a diameter of 10 mm were used to grind approximately 5 g of the powder mixture; the grinding time was 2 hours at 600 rpm. This resulted in a brown mixture, from which the balls were removed by sieving.

[0091] 1.0 g of the ground mixture was charged into a die set from Specac and pressed into tablets at a contact pressure of 500 kg (equivalent to approximately 620 bar) for 15 minutes.

[0092] The pellets were then placed in an alumina crucible in a tube furnace and calcined under a low nitrogen flow (20 L / h). The heated, nitrogen-flowing furnace tube was made of quartz glass. First, it was heated to 300°C and held at this temperature for 2 hours. The furnace temperature was then increased. The furnace temperature was then raised to 700°C over approximately 30 minutes and held at this temperature for 24 hours.

[0093] After cooling to room temperature, the crucible was placed in an airtight glove box. The tablets did not disintegrate and were black.

[0094] Yield: 0.87 g (weight loss 13.1%, corresponding to 99% of theory).

[0095] XRD: Mixture of: Li2NiO2, 23 wt.%; NiO, 51 wt.%; Li2O, 26 wt.%.

[0096] Example 2 (Comparative Example)

[0097] Li2NiO2 is produced from NiO and Li2O

[0098] In an argon-filled glove box, 1.429 g (47.8 mmol) of lithium oxide (99%, BET = 2.4 m 2 / g, supplier: Albemarle, Germany) and 3.571g (47.8mmol) of nickel(II) oxide (NiO green, product number SIAL399523-100G, from Sigma-Aldrich) were mixed and pre-ground in an agate mortar and then ground together in a Fritsch planetary ball mill (Pulverisette 7, in an Easy G™ grinding bowl made of ZrO). Approximately 5g of the powder mixture was ground using 12 ZrO balls with a diameter of 10mm; the grinding time was 2 hours at 600 rpm. The resulting brownish-grey mixture was sieved to remove the balls.

[0099] 1.0 g of the ground mixture was charged into a die set from Specac and pressed into tablets at a contact pressure of 500 kg (equivalent to approximately 620 bar) for 15 minutes.

[0100] The pellets were then placed in an alumina crucible in a tubular furnace and calcined under a weak nitrogen flow. The heated nitrogen flow furnace tube was made of quartz glass. First, it was heated to 300°C and held at this temperature for 2 hours. The furnace temperature was then raised to 700°C. Then, the furnace temperature was raised to 700°C and held at this temperature for 24 hours.

[0101] After cooling to room temperature, the crucible was placed in an airtight glove box. The tablets did not disintegrate and were black.

[0102] Yield: 1.0 g (no apparent weight loss).

[0103] XRD: Mixture of: Li2NiO2, 11 wt%; NiO, 60 wt%; Li2O, 29 wt%.

[0104] Experiments have shown that, by controlling the method of the present invention, the desired Li2NiO2 can be formed using Li2O2, and the oxygen generated during the first calcination step does not change the oxidation number of the NiO used. Surprisingly, the conversion when using Li2O2 is more than twice that when using Li2O.

[0105] The degree of conversion can be further improved by optimizing the experimental conditions, especially by extending the calcination time.

Claims

1. A method for preparing perlithiated lithium metal oxide by reacting lithium peroxide with at least one transition metal oxide or a manganese-containing spinel compound, It is characterized by a) lithium peroxide Li2O2 and at least one transition metal oxide M a O b or manganese-containing spinel compounds, and subsequently b) calcining the mixture, in The 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 LiNi 0.5 Mn 1.5 O4, and a is a number from 1 to 3, and b is a number from 1 to 4, and calcining the mixture successively at at least two successively different temperature levels, In b), the first temperature level is in the range of 280 to 450°C, and the second temperature level is in the range of 500 to 950°C.

2. The method according to claim 1, characterized in that The first temperature is preferably in the range of 300 to 400° C., and the second temperature is preferably in the range of 600 to 900° C., wherein the calcination time at the first temperature is preferably in the range of 0.5 to 20 hours, in particular 1 to 10 hours, and wherein the calcination time at the second temperature is independently preferably in the range of 1 to 96 hours, preferably 1 to 72 hours, more preferably 2 to 72 hours, even more preferably 2 to 48 hours.

3. The method according to any one of claims 1 or 2, characterized in that The calcination at the first and second temperatures is carried out under vacuum or 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 free of water / moisture and CO 2 , wherein the inert gas / gas mixture preferably contains nitrogen, argon or helium, and wherein the calcination at the second temperature is additionally carried out in the absence of oxygen.

4. The method according to any one of claims 1 to 3, characterized in that The two calcination steps are carried out in the same reaction vessel at different temperature levels, and the requirements of the two reaction steps for different temperature and atmosphere conditions are ensured by time or space separation measures.

5. The method according to any one of claims 1 to 4, characterized in that The specific surface area is at least 1m 2 / g, preferably at least 2m 2 / g of lithium peroxide.

6. The method according to any one of claims 1 to 5, characterized in that The calcination is carried out in a corrosion-resistant and high-temperature resistant reactor, the construction material of the reactor being, in particular, a high-temperature resistant material resistant to corrosion by alkaline lithium salts, preferably a metal material selected from high-temperature resistant Cr- and / or Al-containing materials (in particular, nickel-based alloys containing Cr and / or Al, austenitic steels containing Ni and Cr, low-Ni or Ni-free ferritic steels containing Cr and Al, or mixed austenitic-ferritic steels containing chromium), oxide ceramics (in particular, Al2O3), lithium aluminate ceramics (LiAlO2), Ce-based ceramics (in particular, Ce-stabilized ZrO2), non-oxide ceramics (in particular, carbides, preferably SiC, BC, TiC; nitrides, preferably TiN, AlN; and borides, preferably NbB2, BN, Al-infiltrated TiB2, "TiBAl").

7. The method according to any one of claims 1 to 6, characterized in that The method is carried out under static conditions, wherein a mixture of transition metal oxide and Li2O2 in a corrosion-resistant housing or as bulk material on a belt is first heated to 280 to 450°C under vacuum conditions or in an inert gas atmosphere, wherein thermal decomposition of the Li2O2 occurs with the release of oxygen, and after the decomposition of the Li2O2 is complete, while ensuring an oxygen-free atmosphere, the higher temperature of 500 to 950°C required for the formation of the overlithiated metal oxide is established.

8. The method according to any one of claims 1 to 6, characterized in that The process is carried out in a reactor under moving bed conditions to ensure continuous mixing of the reaction mixture.

9. The method according to claim 8, characterized in that The reactor is preferably a continuously operated heatable rotating tube having at least two different temperature zones, wherein in the feed mixture inlet zone the temperature is 280-450° C., and in the rear zone near the product discharge zone the temperature is 500-950° C., wherein in the temperature zone of 500-950° C. appropriate conditions are set to form the overlithiated lithium metal oxide by overflowing an inert gas or an inert gas mixture substantially free of O 2 , CO 2 and H 2 O.

10. The method 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 at an energy input in the range of about 10 to 500 kW / m 3 The mixing is carried out in a rotary mixer or in a mill, in particular an impact rotor mill (impact mill), a grinding media mill or a pin mill.

11. The method according to any one of claims 1 to 10, characterized in that Prior to calcination, the mixture of lithium peroxide and at least one transition metal oxide or manganese-containing spinel compound is compressed using a contact pressure in the range from 0.001 to 100 kbar, preferably from 0.01 to 50 kbar.

12. The method according to any one of claims 1 to 11, characterized in that The transition metal oxide is selected from the oxides of nickel, manganese, cobalt or iron, preferably NiO, CoO, Fe2O3, Fe3O4 and FeO, particularly preferably NiO, CoO and Fe2O3.

13. The method according to any one of claims 1 to 12, characterized in that The mixing molar ratio of Li2O2 to the transition metal oxide is in the range of 0.6:1 to 3:1, preferably 0.9:1 to 3:1, and in particular 1:1 when M=Ni.

14. The method according to any one of claims 1 to 13, characterized in that The over-lithiated lithium metal oxide is Li 2+x FeO4(x=>0to 3);Li 1+x NiO2(x=>0to 1);Li 1+x CoO 1.5+0.5x (x=>0to 5);Li 1+x Mn2O4(x=>0to 1);Li 1+x Ni 0.5 Mn 1.5 O4 (x=>0 to 1), preferably Li5FeO4, Li2NiO2, Li6CoO4, Li2Mn2O4 or Li2Ni 0.5 Mn 1.5 O4, wherein preferably, the over-lithiated lithium metal oxide is Li2NiO2, and the mixing molar ratio Li2O2:NiO is 1:

1.

15. Use of the perlithiated metal oxide compound prepared by the method according to any one of claims 1 to 14 for pre-lithiation in the production of lithium-ion batteries.

Images