Method for manufacturing cathode active material for lithium secondary battery
View Patent ↗Provided is a method for manufacturing a cathode active material for a lithium secondary battery, the method including heat-treating a precursor aqueous solution containing a lithium precursor, a transition metal precursor, and an organic acid containing a carboxyl group, and having a chelation index (C.I) value less than 1 and 0.5 or more, wherein the chelation index value is defined by transmittance of a peak located in a wavenumber from 1,700 to 1,710 cm −1 and transmittance of a peak located in a wavenumber from 1,550 to 1,610 cm −1 in Fourier transform infrared (FTIR) spectroscopy spectrum.
1. A method for manufacturing a cathode active material for a lithium secondary battery, comprising:
gelling a precursor aqueous solution containing a lithium precursor, a transition metal precursor, and an organic acid containing a carboxyl group to prepare a precursor gel having Fourier transform infrared (FTIR) spectroscopy spectrum satisfying the following Equation 2 by the definition of the following Equation 1, and
heat-treating the precursor gel:
Chelation
Index
(
C
.
I
.
)
=
100
-
%
Transmittance
(
1550
)
(
100
-
%
Transmittance
(
1550
)
+
(
100
-
%
transmittance
(
1700
)
(
Equation
1
)
0.640≤C.I.≤0.763 (Equation 2)
wherein in Equation 1 above, % Transmittance (1700) means transmittance of a peak located at a wavenumber from 1,700 to 1,710 cm −1 in FTIR spectrum of the precursor gel and % Transmittance (1550) means transmittance of a peak located at a wavenumber from 1,550 to 1,610 cm −1 in the same FTIR spectrum,
wherein gelling the precursor aqueous solution is performed at 60 to 90° C. under a pressure of 100 mbar to 300 mbar.
2. The method of claim 1 , wherein the transition metal precursor is a precursor of one or two or more metals selected from a group consisting of nickel, cobalt, manganese, aluminum, magnesium, chromium, iron, zirconium, titanium, zinc, scandium, yttrium, niobium, molybdenum and ruthenium.
3. The method of claim 1 , wherein the lithium precursor and the transition metal precursor are each independently nitrates, acetates, hydroxides, chlorides, sulfur oxides, or mixtures thereof.
4. The method of claim 1 , wherein the precursor aqueous solution contains the lithium precursor and the transition metal precursor so as to satisfy the following Equation 3 or 4:
Li 1+x Ni α Mn β Co γ M′ δ O 2 (Equation 3)
LiMn 2−y M″ y O 4 (Equation 4)
wherein in Equation 3 above, x is an actual number satisfying −0.04≤x<1, α, β, γ, and δ are actual numbers satisfying α+β+γ+δ=1 and 0≤α<1, 0≤β<1, 0≤γ<1, and 0≤δ<1, and M′ is one or more metals selected from aluminum, magnesium, chromium, iron, zirconium, titanium, zinc, scandium, yttrium, niobium, molybdenum and ruthenium, and wherein in Equation 4 above, y is an actual number satisfying 0≤y<2 and M″ is one or more metals selected from nickel, cobalt, aluminum, magnesium, chromium, iron, zirconium, titanium, zinc, scandium, yttrium, niobium, molybdenum and ruthenium.
5. The method of claim 4 , wherein the precursor aqueous solution has a molar concentration of lithium ions of 0.1M to 7.0M.
6. The method of claim 1 , wherein the heat-treating is performed at 200 to 1000° C.
7. The method of claim 6 , wherein the heat-treating is a spray pyrolysis process.
8. The method of claim 2 , wherein the heat-treating is performed at 200 to 1000° C.
9. The method of claim 3 , wherein the heat-treating is performed at 200 to 1000° C.
10. The method of claim 4 , wherein the heat-treating is performed at 200 to 1000° C.
11. The method of claim 5 , wherein the heat-treating is performed at 200 to 1000° C.