TITLE OF INVENTION
METHOD FOR REUSING ACTIVE MATERIAL BY USING POSITIVE
5 ELECTRODE SCRAP
TECHNICAL FIELD
The present disclosure relates to a method for reusing resources in the fabrication
of a lithium secondary battery. More particularly, the present disclosure relates to a
10 method for collecting and reusing a positive electrode scrap generated in the lithium
secondary battery fabrication process or positive electrode active materials of lithium
secondary batteries discarded after use. The present application claims the benefit of
Korean Patent Application No. 10-2020-0125730 filed on September 28, 2020 with the
Korean Intellectual Property Office, the disclosure of which is incorporated herein by
15 reference in its entirety.
BACKGROUND ART
Lithium secondary batteries that can be recharged repeatedly are gaining attention
as an alternative to fossil energy. They have been primarily used in traditional handheld
20 devices such as mobile phones, video cameras and electric power tools. Recently, the
range of applications tends to gradually extend to vehicles which are powered by
electricity (EVs, HEVs, PHEVs), large-capacity energy storage systems (ESSs) and
uninterruptible power systems (UPSs).
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A lithium secondary battery includes an electrode assembly including unit cells,
each unit cell including a positive electrode plate and a negative electrode plate including a
current collector and an active material coated on the current collector with a separator
interposed between the positive electrode plate and the negative electrode plate, and a
5 packaging or a battery case in which the electrode assembly is hermetically received
together with an electrolyte solution. The lithium secondary battery primarily includes
lithium-based oxide as the positive electrode active material and a carbon-based material
as the negative electrode active material. The lithium-based oxide contains a metal such
as cobalt, nickel or manganese. In particular, cobalt, nickel and manganese are very
10 expensive invaluable metals. Among them, cobalt is a strategic metal, and its supply is
the focus of attention all over the world. Due to the limited number of cobalt producing
countries, the global supply of cobalt is unstable. When a supply and demand imbalance
of strategic metal occurs, there is a very high possibility that the cost of the raw material
will rise.

WHAT IS CLAIMED IS:
1. A method for reusing a positive electrode active material, comprising:
(a) dry-milling a positive electrode scrap comprising a lithium composite
5 transition metal oxide positive electrode active material layer on a current collector to
bring the active material layer into a powdered state and separate from the current
collector;
(b) thermally treating the active material layer in powder form in air after addition
of a lithium precursor for overcoating or doping of lithium from the lithium precursor on a
10 surface of the active material layer and thermal decomposition of a binder and a
conductive material in the active material layer, to collect an active material; and
(c) washing the collected active material with a lithium compound aqueous
solution which is basic in an aqueous solution and drying to obtain a reusable active
material.
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2. The method for reusing a positive electrode active material according to
claim 1, further comprising:
(d) surface-coating the dried active material.
20 3. The method for reusing a positive electrode active material according to
claim 1, wherein the dry-milling uses any one of a pin mill, a disc mill, a cutting mill and a
hammer mill.
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4. The method for reusing a positive electrode active material according to
claim 1, further comprising:
shredding or cutting the positive electrode scrap before the dry-milling.
5 5. The method for reusing a positive electrode active material according to
claim 1, wherein the thermal treatment is performed at 300 to 1000℃.
6. The method for reusing a positive electrode active material according to
claim 1, wherein the lithium compound aqueous solution contains a lithium precursor in an
10 amount of more than 0% and 15% or less, and the washing is performed for 1 hour or less.
7. The method for reusing a positive electrode active material according to
claim 1, wherein the washing is performed by stirring the collected active material at the
same time with immersing in the lithium compound aqueous solution.
15
8. The method for reusing a positive electrode active material according to
claim 1, wherein the lithium precursor is at least one of LiOH, Li2CO3, LiNO3 or Li2O.
9. The method for reusing a positive electrode active material according to
20 claim 1, wherein a temperature of the thermal treatment step exceeds a melting point of the
lithium precursor.
10. The method for reusing a positive electrode active material according to
37
claim 2, wherein the surface-coating step includes coating at least one of a metal, an
organic metal or a carbon material on the surface by a solid or liquid phase process, and
thermally treating at 100 to 1200℃.
5 11. The method for reusing a positive electrode active material according to
claim 1, wherein the reusable active material is represented by the following Formula 1:
[Formula 1]
LiaNixMnyCozMwO2+δ
where M comprises at least one selected from the group consisting of B, W, Al, Ti
10 and Mg, 1