Positive electrode active material for lithium secondary battery
The present invention provides a positive electrode active material for lithium secondary batteries, comprising domain-oriented agglomerated particles, wherein each of the domain-oriented agglomerated particles comprises a plurality of individually oriented secondary particles such that adjacent secondary particles thereof have mutually different orientation directions, and wherein each of the individually oriented secondary particles is composed of a plurality of primary particles which are composed of a lithium complex oxide with a layered rock-salt structure and are oriented such that the (003) planes of the primary particles do not intersect each other at least in one axial direction. According to the present invention, a positive electrode active material can be provided that is capable of achieving not only high initial output performance but also a high output performance retention rate when charging and discharging are performed repeatedly.
1. A positive electrode active material for lithium secondary batteries, comprising domain-oriented agglomerated particles,
wherein each of the domain-oriented agglomerated particles comprises a plurality of individually oriented secondary particles such that adjacent secondary particles thereof have mutually different orientation directions, wherein the domain-oriented agglomerated particles have an average pore diameter of 0.1 to 5 μm and have an average particle diameter of 1 to 100 μm, and
wherein each of the individually oriented secondary particles is composed of a plurality of primary particles which are composed of a lithium complex oxide with a layered rock-salt structure and are oriented such that the (003) planes of the primary particles do not intersect each other at least in one axial direction.
2. The positive electrode active material according to claim 1 , wherein in each of the individually oriented secondary particles, the plurality of primary particles are oriented such that the (003) planes thereof are approximately parallel to each other.
3. The positive electrode active material according to claim 1 , wherein the domain-oriented agglomerated particles have an open pore structure.
4. The positive electrode active material according to claim 1 , wherein the domain-oriented agglomerated particles have an open pore ratio of 50% or greater and a voidage of 1 to 30%.
5. The positive electrode active material according to claim 1 , wherein the domain-oriented agglomerated particles as a whole have an orientation ratio of (003) planes of 20% or less.
6. The positive electrode active material according to claim 1 , wherein the individually oriented secondary particles have an average particle diameter of 0.1 to 20 μm.
7. The positive electrode active material according to claim 1 , wherein the primary particles have an average particle diameter of 0.1 to 5 μm.
8. The positive electrode active material according to claim 7 , wherein a value obtained by dividing the average particle diameter of the primary particles by the average pore diameter is 0.1 to 5.
9. The positive electrode active material according to claim 1 , wherein the primary particles have an average aspect ratio of 1.0 or more and less than 2.0.