Positive electrode active material particle including core containing lithium cobalt oxide and shell containing composite metal oxide and preparation method thereof
A positive electrode active material particle includes a core that contains lithium cobalt oxide represented by the following Chemical Formula Li a Co (1-x) M x O 2-y A y and a shell that is coated on the surface of the core and contains composite metal oxide of a metal with an oxidation number of +2 and a metal with an oxidation number of +3. In particular, M is at least one selected from the group consisting of Ti, Mg, Zn, Si, Al, Zr, V, Mn, Nb and Ni. A is oxygen-substitutional halogen and 1.00≤a≤1.05, 0≤x≤0.05, and 0≤y≤0.001.
1. A positive electrode active material particle, comprising:
a core, wherein the core is LiCoO 2 ; and
a shell that is coated on a surface of the core, wherein the shell is CoAl 2 O 4 having a layered crystal structure,
wherein a thickness of the shell is about 5 nanometer to about 100 nanometer.
2. The positive electrode active material particle of claim 1 , wherein the shell is formed on the area of about 50% to about 100% of the surface area of the core.
3. The positive electrode active material particle of claim 1 , wherein the positive electrode active material particle further includes an outermost surface layer that is coated on the shell and includes a composite metal oxide of a metal with an oxidation number of +2 and a metal with an oxidation number of +3.
4. The positive electrode active material particle of claim 3 , wherein at least one of metals that forms the outermost surface layer is a metal not included in the shell.
5. A secondary battery comprising a positive electrode including the positive electrode active material particle of claim 1 , a negative electrode, and an electrolyte.
6. The secondary battery of claim 5 , wherein the electrolyte includes electrolyte additives and dinitrile additive,
wherein the electrolyte additives include at least one of ethylene carbonate, vinyl acetate, vinyl ethylene carbonate, thiophene, 1,3-propane sultone, succinic anhydride, and wherein the dinitrile additive is at least one of malononitrile, succinonitrile, glutaronitrile, adiponitrile, and phthalonitrile.
7. A battery pack comprising the secondary battery of claim 5 .
8. A device comprising the battery pack of claim 7 .