Nickel-based lithium metal composite oxide, method of preparing the same, and lithium secondary battery including positive electrode including the same
A nickel-based lithium metal composite oxide including secondary particles including aggregates of primary particles. The secondary particles include i) large secondary particles having a particle size of at least about 14 μm and including aluminum and ii) small secondary particles having a particle size of no more than about 5 μm and including manganese, and a manganese content by mole percent of each of the large secondary particles is smaller than a manganese content by mole percent of each of the small secondary particles and manganese is included on a surface of each of the large secondary particles and aluminum is included on a surface of each of the small secondary particles.
1 . A nickel-based lithium metal composite oxide comprising secondary particles including aggregates of primary particles,
wherein:
the secondary particles comprise i) large secondary particles having a particle size of at least 14 μm and including aluminum and ii) small secondary particles having a particle size of no more than 5 μm and including manganese;
each of the large secondary particles comprises a core and a surface layer around the core, and each of the small secondary particles comprises a core and a surface layer around the core;
a manganese content by mole percent of the large secondary particles based on total moles of metal excluding lithium of the large secondary particles is smaller than a manganese content by mole percent of the small secondary particles based on total moles of metal excluding lithium of the small secondary particles; and
the surface layer of at least some of the large secondary particles comprises aluminum and from 0.01 mol % to 0.2 mol % manganese based on a total amount of transition metals of the large secondary particles,
the manganese on the surface layer of the large secondary particles is a kind of manganese from a precursor of the small secondary particles, and
the surface layer of at least some of the small secondary particles comprises manganese and from 0.01 mol % to 0.2 mol % aluminum based on a total amount of transition metals of the small secondary particles,
wherein the core of each of the small secondary particles consists of a compound represented by Formula 2:
Li a (Ni 1−x−y−z Co x Mn y M z )O 2±α1 , and Formula 2
wherein in Formula 2, M is boron, magnesium, calcium, strontium, barium, titanium, vanadium, chromium, iron, copper, or zirconium,
0.95≤a≤1.1, 0.6≤(1-x-y-z)<1, 0<x<0.4, 0<y<0.4, 0≤z<0.4, and 0≤α 1 ≤0.1.
2 . The nickel-based lithium metal composite oxide of claim 1 , wherein the core of each of the large secondary particles excludes manganese or the core of at least some of the large secondary particles comprises from 0.01 mol % to 0.5 mol % manganese based on total moles of metal excluding lithium of the large secondary particles.
3 . The nickel-based lithium metal composite oxide of claim 1 , wherein the cores of at least some of the small secondary particles each comprise from 0.5 mol % to 5 mol % manganese based on total moles of metal excluding lithium of the small secondary particles.
4 . The nickel-based lithium metal composite oxide of claim 1 , wherein some of the large secondary particles have a particle size of 14 μm to 20 μm.
5 . The nickel-based lithium metal composite oxide of claim 1 , wherein some of the small secondary particles have a particle size of 1 μm to 5 μm.
6 . The nickel-based lithium metal composite oxide of claim 1 , wherein the nickel-based lithium metal composite oxide comprises at least 60 mol % nickel based on total moles of metal excluding lithium of the nickel-based lithium metal composite oxide.
7 . The nickel-based lithium metal composite oxide of claim 1 , wherein an amount of the large secondary particles is from 30 parts by weight to 90 parts by weight based on 100 parts by weight of a total amount of the large secondary particles and the small secondary particles.
8 . The nickel-based lithium metal composite oxide of claim 1 , wherein the core of each of the large secondary particles consists of a compound of Formula 1 below:
Li a (Ni 1−x−y−z Co x Al y M z )O 2±α1 Formula 1
wherein in Formula 1, M is boron, magnesium, calcium, strontium, barium, titanium, vanadium, chromium, iron, copper, or zirconium,
0.95≤a≤1.1, 0.6≤(1-x-y-z)<1, 0<x<0.4, 0<y<0.4, 0≤z<0.4, and 0≤α 1 ≤0.1.
9 . The nickel-based lithium metal composite oxide of claim 1 , wherein in Formula 2, 0.001<y<0.3.
10 . The nickel-based lithium metal composite oxide of claim 1 , wherein at least some of the large secondary particles comprise from 0.5 mol % to 5 mol % aluminum based on total moles of metal excluding lithium of the large secondary particles.
11 . A method of preparing the nickel-based lithium metal composite oxide according to claim 1 , the method comprising the steps of:
preparing a precursor mixture by mixing a large precursor having a size of at least 14 μm and including aluminum, a small precursor having a size of no more than 5 μm and including manganese, and a lithium precursor; and
heat-treating the precursor mixture,
wherein the heat-treating is performed at a temperature of 600° C. to 900° C. to simultaneously treat the large precursor and the small precursor to obtain the secondary particles of the nickel-based lithium metal composite oxide,
wherein the large precursor comprises from 0.5 mol % to 5 mol % aluminum based on total moles of metal of the large precursor, and
wherein the small precursor does not comprise aluminum.
12 . The method of claim 11 , wherein:
the large precursor excludes manganese or the large precursor comprises from 0.01 mol % to 0.5 mol % manganese based on total moles of metal of the large precursor; and
the small precursor comprises from 0.5 mol % to 5 mol % manganese based on total moles of metal of the small precursor.
13 . The method of claim 11 , wherein the lithium precursor comprises an anhydrous lithium hydroxide, a lithium hydroxide hydrate, a lithium fluoride, a lithium carbonate, or any mixture thereof.
14 . A positive electrode comprising the nickel-based lithium metal composite oxide of claim 1 .
15 . A lithium secondary battery comprising the positive electrode of claim 14 , a negative electrode, and an electrolyte therebetween.
16 . A metal oxide composite comprising nickel, lithium, and secondary particles including aggregates of primary particles, wherein:
the secondary particles comprise i) large secondary particles having a particle size of at least 14 μm and including aluminum and ii) small secondary particles having a particle size of no more than 5 μm and including manganese;
each of the large secondary particles comprises a core and a surface layer around the core;
each of the small secondary particles comprises a core and a surface layer around the core;
a manganese content by mole percent of at least some of the large secondary particles is smaller than a manganese content by mole percent of at least some of the small secondary particles;
the surface layer of at least some of the large secondary particles comprises aluminum and from 0.01 mol % to 0.2 mol % manganese based on a total amount of transition metals of the large secondary particles;
the manganese on the surface layer of the large secondary particles is a kind of manganese from a precursor of the small secondary particles; and
the surface layer of at least some of the small secondary particles comprises manganese and from 0.01 mol % to 0.2 mol % aluminum based on a total amount of transition metals of the small secondary particles,
wherein the core of each of the small secondary particles consists of a compound represented by Formula 2:
Li a (Ni 1−x−y−z Co x Mn y M z )O 2±α1 , and Formula 2
wherein in Formula 2, M is boron, magnesium, calcium, strontium, barium, titanium, vanadium, chromium, iron, copper, or zirconium,
0.95≤a≤1.1, 0.6≤(1-x-y-z)<1, 0<x<0.4, 0<y<0.4, 0≤z<0.4, and 0≤α 1 ≤0.1.