WO2017037179A1

WO2017037179A1 - Mixed oxide surrounded by a shell and containing manganese and lithium

Info

Publication number: WO2017037179A1
Application number: PCT/EP2016/070620
Authority: WO
Inventors: Stipan Katusic; Michael Hagemann; Peter Kress; Armin Wiegand
Original assignee: Evonik Degussa Gmbh
Priority date: 2015-09-03
Filing date: 2016-09-01
Publication date: 2017-03-09
Also published as: DE102015216901A1

Abstract

The invention relates to a core-shell particle (1) wherein the core comprises a mixed oxide containing lithium and manganese, and a) the shell consists largely of silicon dioxide and aluminium oxide, or b) the shell consists largely of silicon dioxide or aluminium oxide and the core also contains at least one additional oxide of a metal M, where M = AI, B, Ca, Nb, Ta, Ti and V, and c) the BET surface area is 10-30 m²/g.

Description

Enveloped lithium and manganese-containing mixed oxide

The invention relates to a sheath surrounded, containing lithium and manganese mixed oxide, its preparation and use.

US2005 / 106463 discloses an electrode material for a lithium secondary battery containing mixed lithium / transition metal oxides and boron. The electrode material has a specific surface area of 0.1 to 8 m ² / g and a tamped density of 1.6 g to 3.0 g / cm ³ . The electrode material is prepared by mixing a mixture of a lithium, nickel, manganese and cobalt compound and boric acid in the desired stoichiometric ratio with each other, from which produces a dispersion in water, the dispersion milled until a particle diameter of 30 μιτι is reached. This is followed by spray drying. The material thus obtained is thermally treated at elevated temperature. The tamped density varies with the type of thermal treatment. The method mentioned in US2005 / 106463 comprises many steps. It is known to produce electrode materials in a simpler way via a flame spray pyrolysis. Thus, in WO 201 1/160940 a process for the preparation of a lithium-containing

Mixed oxide powder disclosed in which a solution of a lithium compound and a

Metal compound containing as metal component Ag, Al, B, Ca, Cd, Co, Cr, Cu, Fe, Ga, Ge, In, Mg, Mn, Mo, Nb, Ni, Pd, Rh, Ru, Sc, Sn, Ti , V, Y or Zn is atomized by means of a nebulizer gas to an aerosol and burned in an oxygen / hydrogen flame.

EP-A-3026019 discloses a powdered cathode material in the form of aggregated primary particles comprising a mixed oxide powder which has a composition corresponding to

Lii + x (Ni _a CobMn _c ) DdO 2, and H and N as a non-metal component, having a content of H 0.01 - 0, 1 wt .-% and a content of N of 0.002-0.05 wt .-% and wherein D = Ag, Al, B, Ca, Cr, Cu, Fe, Ga, Ge, In, K, Mg, Mo, Na, Nb, Si, Sn, Ta, Ti, Ti, V, and Zr and 0 <x <0.2; 0 <a <1; 0 <b <1; 0 <c <1, 0 <d <0.2. It is prepared by adding a solution containing a lithium compound and at least one other metal compound selected from the group consisting of Mn, Ni and Co and an ammonia-containing aerosol in one

High temperature zone brings to reaction. In principle, all soluble doping compounds which are oxidizable can be used. These may be inorganic metal compounds or organic metal compounds. A particularly preferred doping component is Al. The doping compound is preferably used in an amount such that the later cathode material does not contain more than 10% by weight of doping component, more preferably 0.1 to 5% by weight.

Kalaignan et al. in Journal of Power Sources 196 (201 1) 3640-3645 describe the preparation of silica-clad LiMn204 cathode material via a gel route and subsequent thermal treatment. Accordingly, the crystal structure is not changed by the shell, the electrochemical properties improved. Park et al. in Journal of Power Sources 126 (2004) 150-155 describe the preparation of alumina-clad LiMn2-xZr _x 04 via a sol-gel route. Again, the cladding leads to improved electrochemical properties, as compared to the non-clad material.

The object of the present invention was to provide cathode materials which have again improved electrochemical properties compared with this prior art. Another object was to provide a method for these cathode materials.

The invention relates to core-shell particles (1), wherein the core comprises a mixed oxide containing lithium and manganese, characterized in that

a) the shell largely consists of silica and alumina or

b) the shell consists largely of silica or alumina and

the core additionally contains at least one further oxide of a metal M with M = Al, B, Ca, Nb, Ta,

Ti and V contains and

c) the BET surface area is 10 to 30 m ² / g, preferably 15 to 25 m ² / g.

The silica is an X-ray amorphous silica. Boron should be considered as metal in the context of this invention.

The present invention claims two types of core shell particles. The core-shell particles (1) have, for example, a higher BET surface area than the core-shell particles (2). The core-shell particles (1) are the product of flame spray pyrolysis. The core-shell particles (2) can be obtained by thermal aftertreatment of the core-shell particles (1).

Mixed oxide is the intimate mixing of all mixed oxide components to understand. It is therefore largely a mixture at the atomic level, not a physical mixture of oxides. The mixed oxide particles are generally present in the form of aggregated primary particles.

It is possible that the core different mixed oxides with different

Composition contains. As an example, the presence of Lio, 78Mno, 8s02 or Lio, 96Mno, 7402 besides the main phase is called LiMri204.

For the most part, it is to be understood that the coating constituents contain only conventional, due to the production of these products impurities in conventional amounts.

Impurities from silica may be iron oxides, titania, alumina or hydrochloric acid. Impurities from alumina can be iron oxides, titanium oxide,

Be silica or hydrochloric acid. The usual amount is understood to mean that the proportion of the coating constituents silicon dioxide and aluminum oxide is at least 98% by weight, generally at least 99% by weight or 99.5% by weight.

An electrode material based on lithium mixed oxides should have the highest possible tamped density. As a result, the volume of the battery can be kept low for a given energy capacity. The core-shell particles (1) generally have an acceptable tamped density of 300-600 g / l. The BET surface area is determined according to DIN ISO 9277. The tamped density is determined according to DIN EN ISO 787/1 1.

In the case where the shell consists essentially of silica and alumina, a ratio Si / Al of 0, 1-100 mol / mol has been found to be preferred and 0.2-10 mol / mol is particularly preferred.

With respect to the core, for core-shell particles (1), the ratio M / (Li + Mn) is preferably 0.001-0.5 mol / mol, and more preferably 0.005-0.03 mol / mol. Alumina and / or boria are the preferred additional metal oxides in the core. In addition, the core may also contain nickel and / or cobalt.

In a particular embodiment, the core has the composition Lix (Ni _a CobMn _c ) DdO 2, where D = Al, B and 0 <x <0.5; 0 <a <1; 0 <b <1; 0 <c <1; 0 <d <0.2.

If the shell consists essentially of silicon dioxide, it is preferable for D = Al, x = 0.5, a = b = 0 and 0.5 <c <2.

If the shell essentially consists of silicon dioxide and aluminum oxide, x = 0.5, a = b = d = 0 and 0.5 <c <2, where Si / Al = 0.2 to 5 mol / mol are preferred.

Another object of the invention is a process for the preparation of the core-shell particles (1), wherein

a) containing in a first zone of a flow reactor, a mixture

a1) an aerosol containing a lithium compound and manganese compound and

optionally a nickel compound, a cobalt compound or both, and optionally at least one metal compound, with metal M = Al, B, Ca, Nb, Ta, Ti and V,

a2) one or more hydrogen-containing fuel gases and

a3) one or more oxygen-containing gases

ignited in a reaction chamber and allowed to react in the flame, the

Total amount of oxygen sufficient for at least complete conversion of the fuel gas and the metal compounds,

b) in one of the first zone subsequent second zone of the flow reactor to the

Reaction mixture from the first zone

b1) a silicon compound or

b2) an aluminum compound or

b3) a silicon compound and an aluminum compound

gives,

c) subsequently cooling the reaction mixture, if appropriate, and separating the solid from gaseous or vaporous substances.

The aerosol can be prepared by co-sputtering a metal compound and a

Atomizing gas can be obtained by means of one or more nozzles. Lithium, manganese, nickel and cobalt compound, and the metal compound can be used as such even in liquid form or in the form of a solution.

In principle, the nature of the metal compounds is not limited as long as they are hydrolyzable or pyrolyzable under the reaction conditions to form the metal oxides. Thus, for example, chlorides, nitrates or organometallic compounds can be used. It is also possible that the solution contains different metal compounds of one metal or more metal compounds with different metal components. In the latter case mixed metal oxides are formed.

In the method according to the invention, air, oxygen-enriched air and / or an inert gas such as nitrogen can be used as sputtering gas.

It is advantageous for the present invention if the lithium, manganese, nickel and

Cobalt compound, as well as the metal compound in a solution. In order to achieve solubility and to achieve a suitable viscosity for sputtering the solution, the solution can be heated. Particular preference may be given to using water or a mixture of water and an organic solvent. As organic solvents,

or as a constituent of organic solvent mixtures, preference may be given to alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol or tert-butanol, diols such as ethanediol, pentanediol, 2-methyl-2,4-pentanediol, C1- C12 carboxylic acids such as acetic, propionic, butanoic, hexanoic, oxalic, malonic, succinic, glutaric, adipic, octanoic, 2-ethylhexanoic, valeric, capric,

Lauric acid can be used. Furthermore, benzene, toluene, naphtha and / or gasoline can be used. Preferably, an aqueous solvent is used.

In the second zone of the flow-through reactor, a silicon compound and / or aluminum compound, each of which is hydrolyzable or pyrolyzable, is added to the reaction mixture from the first zone.

These are preferably selected from the group consisting of SiCU, CH ₃ SCl ₃ , (Ch 2 SiCk, (CH ₂ SiCl, HSiCIs, (CH ₃ ) ₂ HSiCl and CH ₃ C ₂ H ₅ SCl 2, H ₄ Si, Si (OC ₂ H ₅ ) 4 and Si (OCH ₃ ) ₄ and the

An aluminum compound selected from the group consisting of aluminum alcoholates, such as

Aluminum isopropylate or aluminum sec-butylate, aluminum carboxylates such as aluminum acetate and aluminum 2-ethylhexanoate, and aluminum acetylacetonate.

The timing of addition of the silicon compound and / or aluminum compound is to be chosen so that the particle formation of the core constituents in the first zone is well advanced or already completed. This time depends among other things on the execution of the

Flow reactor and the starting materials. In general, the average residence time in the first zone and the second zone is independently 0.1 - 10 s.

A particular embodiment provides that ammonia is introduced into the reaction space. This can be achieved, for example, by adding ammonia to the aerosol. The concentration of ammonia is preferably 0.01-2 Nm ³ / mol (Li + Mn), more preferably 0.05-1.5 Nim ³ / mol (Li + Mn). The addition of ammonia seems to affect the

Homogeneity and crystallinity of the material to have.

Another object of the invention are core-shell particles (2), wherein the core comprises a lithium and manganese-containing mixed oxide, and

a) the shell largely consists of silica and alumina or

b) the shell consists largely of silica or alumina and

the core additionally contains at least one further oxide of a metal M with M = Al, B, Ca, Nb, Ta, Ti and V and

c) the BET surface area is less than 10 m ² / g.

These particles are to be referred to in the context of the present invention as core-shell particles (2). They differ from the core-shell particles (1), inter alia, in a lower BET surface area and a higher crystallinity.

In a particular embodiment, the further metal oxide is alumina and the tamped density of the core-shell particles (2) is 700-1500 g / l.

Another object of the invention is a process for the preparation of the core-shell particles (2) in which the core-shell particles (1) are thermally treated. Preferably, this is done at 800 to 1000 ° C and over a period of 1 to 10 hours.

Thus, the production of the core-shell particles (2) comprises the process steps for the production of the core-shell particles (1). Overall, the production of the core-shell particles (2) includes a

Method in which one

a) containing in a first zone of a flow reactor, a mixture

a1) an aerosol containing a lithium compound and manganese compound and

a2) one or more hydrogen-containing fuel gases and

a3) one or more oxygen-containing gases

ignited in a reaction chamber and allowed to react in the flame, the

in one of the first zone subsequent second zone of the flow reactor to the

Reaction mixture from the first zone

b1) a silicon compound or

b2) an aluminum compound or

b3) a silicon compound and an aluminum compound

gives,

c) subsequently, if appropriate, cooling the reaction mixture and separating off the solid from gaseous or vaporous substances, and d) thermally treating the solid, preferably at 800-1000 ° C over a period of 1-10 hours.

Another object of the invention is the use of the core-shell particles (2) produced by the novel process as the cathode material in lithium-ion batteries. Examples

For Examples 1 to 6, first a solution of the metal compound in water is prepared, which forms the core of the core-shell particles. The metal compounds and the composition of the solution are shown in Table 1.

From the solution, atomizing air and possibly ammonia, an aerosol is generated by means of a nozzle, which is atomized into a reaction space. Here a blast gas flame burns out of hydrogen and air, in which the aerosol is brought to the reaction. The mean residence time of the reaction mixture in the first zone is 0.75 s in Examples 1 and 2 and 1.75 s in Examples 3-6.

In the second zone, vapor Si (OC2Hs) 4 and / or vaporous Al (OiBu) 3 is added to the stream of the reaction mixture from the first zone, in each case together with nitrogen, and separately 2.5 kg / h of steam. The average residence time of the reaction mixture in the second zone is 0.9 s in Examples 3-6.

After cooling, the solid is separated on a filter of gaseous substances.

The solid is heated to a temperature of 875 ° C over a period of 4 hours. Table 1 lists the starting materials and reaction conditions, Table 2 lists important

Material properties.

Comparative Example 1 has neither a shell nor an additional metal oxide.

Comparative Example 2 has a SiC shell, but no additional metal oxide in the core. Inventive Example 3 has an SiC shell and Al 2 O 3 as an additional metal oxide in the core.

Inventive Examples 4-6 have a shell of S1O2 and Al2O3 and Al2O3 as an additional metal oxide in the core. The proportion of Al2O3 in Examples 4-6 increases.

Table 2 shows that the shell and the additional AI2O3 in the core leads to an improvement of the electrochemical data. Table 1: Starting materials and reaction conditions

Annealing ²⁾

Oven temperature ° C 875

Annealing time h 4

1) 0 _2- enriched air: 0 ₂ content = 28.9% by volume; 2) Rotary kiln, through which air flows

Table 2: Physico-chemical properties of the powders

1) FSP = flame spray pyrolysis; 2) 2.5-4.8V;

Claims

claims

1. core-shell particles (1) in which the core comprises a lithium and manganese-containing mixed oxide, characterized in that

a) the shell largely consists of silica and alumina or

b) the shell consists largely of silica or alumina and

c) the BET surface area is 10-30 m ² / g.

2. core-shell particles (1) according to claim 1, characterized in that

the shell has a ratio Si / Al = 0, 1-100 mol / mol.

3. core-shell particles (1) according to claims 1 or 2, characterized in that

the ratio M / (Li + Mn) is 0.001-0.5 mol / mol.

4. core-shell particles (1) according to claims 1 to 3, characterized in that

the core contains alumina and / or boron oxide.

5. core-shell particles (1) according to claims 1 to 4, characterized in that

the core contains nickel and / or cobalt.

6. core-shell particles (1) according to claims 1 to 5, characterized in that

the core has the composition Li _x (Ni _a CobMn _c ) DdO 2, where

D = Al, B and 0.5 <x <1, 5; 0 <a <1; 0 <b <1; 0 <c <2; 0 <d <0.2.

7. core-shell particles (1) according to claim 6, characterized in that

D = Al, x = 0.5, a = b = 0 and 0.5 <c <2 and the shell consists essentially of silica.

8. core-shell particles (1) according to claim 6, characterized in that

for the kernel x = 0.5, a = b = d = 0 and 0.5 <c <2; and the shell consists essentially of silica and alumina, where Si / Al = 0.2-5 mol / mol.

9. core-shell particles (1) according to claim 6, characterized in that

for the core D = Al, a = b = x = 0 and 0.5 <c <2 and the shell consists essentially of silica and alumina, where Si / Al = 0.2 to 5 mol / mol.

10. A process for the preparation of the core-shell particles (1) according to claims 1 to 9, characterized in that one

a) containing in a first zone of a flow reactor, a mixture

a1) an aerosol containing a lithium compound and manganese compound and

optionally a nickel compound, a cobalt compound or both, and optionally at least one metal compound, with metal M = Al, B, Ca, Nb, Ta,

Ti and V,

a2) one or more hydrogen-containing fuel gases and

a3) one or more oxygen-containing gases ignited in a reaction space and allowed to react in the flame, wherein the total amount of oxygen is sufficient at least for complete conversion of the fuel gas and the metal compounds,

b) in one of the first zone subsequent second zone of the flow reactor to the reaction mixture from the first zone

b1) a silicon compound or

b2) an aluminum compound or

b3) a silicon compound and an aluminum compound

gives,

1 1. A method according to claim 10, characterized in that

the metal compound is selected from the group consisting of nitrates, chlorides, bromides, alkoxides and carboxylates.

12. The method according to claims 10 or 1 1, characterized in that

the silicon compound used in the second zone and consisting of SiCU, CHsSiCIs, (CH ₃ ) ₂ SiCl ₂ , (CH ₃ ) ₃ SiCl, HSiCIs, (CH ₃ ) ₂ HSiCl and CH ₃ C ₂ H 5 SCl ₂ , H ₄ Si, Si (OC ₂ H ₅ ) 4 and Si (OCH3) 4 and the aluminum compound are selected from the group consisting of aluminum alkoxides, aluminum carboxylates and aluminum acetylacetonate.

13. The method according to claims 10 to 12, characterized in that

in Zone 1 and Zone 2 the mean residence time is 0.1 - 10 s.

14. The method according to claims 10 to 13, characterized in that

ammonia is introduced into the reaction space.

15. core-shell particles (2), wherein the core comprises a mixed oxide containing lithium and manganese, characterized in that

a) the shell largely consists of silica and alumina or

b) the shell consists largely of silica or alumina and

c) the BET surface area is less than 10 m ² / g.

16. core-shell particles (2) according to claim 15, characterized in that

the further metal oxide is alumina and the tamped density is from 700 to 1500 g / l.

17. A process for the preparation of the core-shell particles (2) according to claims 15 or 16,

characterized in that one

the core-shell particles according to claims 1 to 9 thermally treated.

18. Use of the core-shell particles (2) according to claim 15 or 16 as cathode material in lithium-ion batteries.