Cathode active material for lithium secondary battery, method for preparing the same, and method for controlling morphology of the same
Provided is a method for preparing a cathode active material for a lithium secondary battery, and more particularly, the method includes mixing lithium nitrate, nickel nitrate, cobalt nitrate, and manganese nitrate with a solvent to form a mixture, performing first annealing on the mixture to form an NCM precursor including the lithium nitrate and transition metal oxide (NiCoMnO), compressing the NCM precursor to remove voids, and performing second annealing on the NCM precursor to form NCM particles.
1 . A method for preparing a cathode active material for a lithium secondary battery, the method comprising:
mixing lithium nitrate, nickel nitrate, cobalt nitrate, and manganese nitrate with a solvent to form a mixture;
performing a first heat treatment on the mixture to form an NCM precursor, the NCM precursor including the lithium nitrate and transition metal oxide (NiCoMnO);
compressing the NCM precursor to remove voids; and
performing a second heat treatment on the NCM precursor to form NCM particles,
wherein the NCM particles include lithium composite oxide (LiNiCoMnO),
wherein the NCM particles are polycrystalline particles formed by aggregation of primary particles,
wherein the solvent is ketone,
wherein the first heat treatment is performed at about 350° C. to about 600° C., and
wherein the second heat treatment is performed at about 570° C. to about 800° C.
2 . The method of claim 1 , wherein an intensity ratio of (003) to (104) according to XRD analysis of the NCM particles is about 1.3 to about 2.0.
3 . The method of claim 1 , wherein each of the first heat treatment and the second heat treatment is performed at a heating rate of about 3° C./min to about 10° C./min.
4 . The method of claim 1 , further comprising pelletizing the compressed NCM precursor.
5 . The method of claim 1 , wherein during the second heat treatment, lithium ions generated through decomposition of the lithium nitrate are diffused into and bonded with the transition metal oxide.
6 . The method of claim 1 , wherein an atomic fraction of nickel (Ni) to nickel (Ni), cobalt (Co), and manganese (Mn) in the NCM particles is about 85 at % to about 95 at %.
7 . The method of claim 1 , wherein the NCM particles have an average diameter of about 5 μm to about 10 μm.
8 . The method of claim 1 , wherein the voids are generated through the first heat treatment process, and the NCM precursor are compressed to remove the voids.
9 . The method of claim 8 , further comprising:
drying the mixture to remove H 2 O; and
collecting the dried mixture as a powder mixture.
10 . A method for controlling the morphology of a cathode active material for a lithium secondary battery, the method comprising:
mixing lithium nitrate, nickel nitrate, cobalt nitrate, and manganese nitrate with a solvent to form a mixture;
performing first heat treatment on the mixture to form an NCM precursor, the NCM precursor including the lithium nitrate and transition metal oxide (NiCoMnO);
compressing the NCM precursor to remove voids; and
performing second heat treatment on the NCM precursor to form NCM particles,
wherein the NCM particles include lithium composite oxide (LiNiCoMnO),
wherein the NCM particles are polycrystalline particles formed by aggregation of primary particles,
wherein the solvent is ketone,
wherein the first heat treatment is performed at about 350° C. to about 600° C., and
wherein the second heat treatment is performed at about 570° C. to about 800° C., wherein the temperature of the second heat treatment is regulated to control the morphology and crystallinity of the NCM particles.