Spherical particles, production thereof and use
Spherical particles comprising (A) at least one mixed transition metal hydroxide or mixed transition metal carbonate of at least 3 different transition metals selected from nickel, cobalt, manganese, iron, chromium and vanadium, (B) at least one fluoride, oxide or hydroxide of Ba, Al, Zr or Ti, where the transition metals in transition metal hydroxide (A) or transition metal carbonate (A) are predominantly in the +2 oxidation state, where fluoride (B) or oxide (B) or hydroxide (B) is present to an extent of at least 75% in an outer shell of the spherical particles in the form of domains and is encased to an extent of at least 90% by transition metal hydroxide (A) or transition metal carbonate (A).
1. Spherical particles, comprising
(A) a mixed transition metal hydroxide or mixed transition metal carbonate of at least 3 different transition metals selected from the group consisting of nickel, cobalt, manganese, iron, chromium and vanadium; and
(B) a fluoride, oxide or hydroxide of Ba, Al, Zr or Ti,
wherein the transition metals in transition metal hydroxide (A) or transition metal carbonate (A) are predominantly in the +2 oxidation state, and
wherein fluoride (B) or oxide (B) or hydroxide (B) is present to an extent of at least 75% in an outer shell of the spherical particles in the form of domains and is encased to an extent of at least 90% by transition metal hydroxide (A) or transition metal carbonate (A).
2. The spherical particles according to claim 1 , wherein one or more transition metals in transition metal hydroxide (A) or transition metal carbonate (A) are at least partially present in the +3 or +4 oxidation state.
3. The spherical particles according to claim 1 , wherein oxide (B) is selected from the group consisting of BaTiO 3 , Al 2 O 3 and TiO 2 .
4. The spherical particles according to claim 1 , having a median diameter (D50) in the range from 2 to 30 μm.
5. The spherical particles according to claim 1 , wherein the outer shell has a mean thickness of 1 to 15%, based on a diameter of the respective particle.
6. The spherical particles according to claim 1 , wherein the mixed transition metal hydroxide (A) is of formula (I):
Ni a Co b Mn c M d O e (OH) f (I)
wherein
M is Mg and/or at least one transition metal selected from the group consisting of Fe, Cr and V
a is from 0.1 to 0.8,
b is from 0.1 to 0.4,
c is from 0.1 to 0.6,
d is from zero to 0.2,
where: a+b+c+d=1,
e is from 0.05 to 0.5,
f is from 0.5 to 1.9,
and a mean oxidation state of Ni, Co and Mn is from 2.1 to 3.2.
7. The spherical particles according to claim 1 , wherein the mixed transition metal carbonate (A) is of formula (II):
Ni a′ Co b′ Mn c′ M d′ O e′ (OH) j (CO 3 ) h (II)
wherein
M is at least one transition metal selected from the group consisting of Fe, Cr and v,
a′ is from 0.1 to 0.5,
b′ is from zero to 0.3,
c′ is from 0.1 to 0.75,
d′ is from zero to 0.2,
where: a′+b′+c′+d′=1,
e′ is from zero to 0.6,
h is from 0.4 to 1, and
j is from zero to 0.3.
8. The spherical particles according to claim 1 , wherein the spherical particles are of inhomogeneous composition, a mean standard deviation of the composition of nickel, cobalt and manganese being up to 10 mol % in each case.
9. The spherical particles according to claim 1 , wherein the proportion of fluoride (B) or oxide (B) or hydroxide (B) is from 0.3 to 5% by weight, based on transition metal hydroxide (A) or transition metal carbonate (A).
10. A process for producing spherical particles according to claim 1 , the process comprising:
(a) first producing particles of transition metal hydroxide (A) or transition metal carbonate (A);
(b) contacting fluoride (B) or oxide (B) or hydroxide (B) or a solution comprising a salt of Ba, Al, Zr or Ti and optionally a water-soluble fluoride with the particles of transition metal hydroxide (A) or transition metal carbonate (A) obtained in the producing (a), at a different time or reaction vessel from the producing (a); and
(c) producing a further transition metal hydroxide (A) or transition metal carbonate (A) and combining the transition metal hydroxide (A) or transition metal carbonate (A) obtained with the particles obtained in the producing (a),
wherein steps (b) and (c) may run simultaneously or consecutively.
11. The spherical particles according to claim 1 , wherein the spherical particles are suitable for production of lithium-containing mixed transition metal oxides.
12. A process for producing lithium-containing mixed transition metal oxides, comprising mixing spherical particles according to claim 1 with a lithium compound and reacting them with one another at temperatures in the range from 500 to 1000° C.
13. A lithium-containing mixed transition metal oxide in particulate form, comprising
(C) a mixed oxide of lithium and at least 3 different transition metals selected from the group consisting of nickel, cobalt, manganese, iron, chromium and vanadium,
(D) a fluoride or oxide of Ba, Al, Zr or Ti,
wherein fluoride (D) or oxide (D) is present to an extent of at least 75% in an outer shell of the particles in the form of domains and is encased to an extent of at least 90% by oxide (C).
14. The lithium-containing mixed transition metal oxide according to claim 13 , wherein the lithium-containing mixed transition metal oxide is suitable for production of cathode material for lithium ion batteries.