Methods for preparing cathode active material precursor material and cathode active material for lithium secondary battery, and cathode active material for lithium secondary battery prepared according to same
The present disclosure provides: a method for preparing a cathode active material precursor material by using a high-nickel-content waste lithium secondary battery; a method for preparing a cathode active material for a lithium secondary battery, including a cathode active material precursor material prepared by the method for preparing a cathode active material precursor material; and a cathode active material for a lithium secondary battery, prepared according to the method for preparing a cathode active material for a lithium secondary battery.
1 . A method for preparing a cathode active material precursor material using a waste lithium secondary battery, the method comprising:
(1) leaching a cathode active material of the waste lithium secondary battery to obtain a leachate; and
(2) mixing a polar solvent and an alkaline solution and then dissolving an oxime-based material to form a saponified oxime-based material that is saponified to 50% or more; and
(3)precipitating nickel by adding 2 to 20 w/v % of a saponified oxime-based material to the leachate.
2 . The method of claim 1 , wherein the cathode active material of the waste lithium secondary battery includes a cathode active material represented by Formula 1:
LiNi x Co y Mn z O 2 [Formula 1]
wherein 0.5≤x≤1, 0≤y≤0.3, 0≤z≤0.3, and x+y+z=1.
3 . The method of claim 1 , further comprising extracting manganese from the leachate after step (1) and before step (2).
4 . The method of claim 1 , wherein the oxime-based material includes one or more kinds selected from the group consisting of dimethylglyoxime, diethylglyoxime, dipropylglyoxime, and ethylmethylglyoxime.
5 . The method of claim 1 , wherein the alkaline solution includes at least one kind selected from the group consisting of NaOH, KOH, Ca(OH) 2 , and NH 4 OH.
6 . The method of claim 1 , wherein the polar solvent includes at least one kind selected from the group consisting of water, alcohol, acetone, and carboxylic acid.
7 . The method of claim 1 , further comprising obtaining nickel sulfate by treating the precipitated nickel with sulfuric acid in step (3).
8 . The method of claim 1 , wherein the cathode active material of the waste lithium secondary battery is obtained by crushing the waste lithium secondary battery and then heat-treating the crushed waste lithium secondary battery.
9 . The method of claim 1 , comprising obtaining a cathode active material represented by the following formula by mixing lithium salt with a cathode active material precursor material prepared by the method according to claim 1 :
LiNi x′ Co y′ Mn z′ O 2
wherein 0<x′≤1, 0≤y′<1, 0≤z′<1, and x′+y′+z′=1.