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 method
for collecting and reusing positive electrode scrap generated in the lithium secondary battery
10 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. 10-2020-0076728 filed on June 23, 2020 with the Korean Intellectual
Property Office, the disclosure of which is incorporated herein by reference in its entirety.
15 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
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,
20 HEVs, PHEVs), large-capacity energy storage systems (ESSs) and uninterruptible power
systems (UPSs).
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
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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
packaging or a battery case in which the electrode assembly is hermetically received together
with an electrolyte solution. The lithium secondary battery primarily includes lithium5 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 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
10 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.
Studies have been made to collect and recycle invaluable metals from lithium
secondary batteries (waste batteries) discarded after the expiration date. In addition to
waste batteries, resources may be more preferably collected from waste materials discarded
15 after punching the positive electrode plate or the positive electrode in which defects or
failures occurred during the process.
Currently, the lithium secondary battery is fabricated, as shown in FIG. 1, by coating
a positive electrode slurry including a positive electrode active material, a conductive
material, a binder and a solvent on a long sheet-type positive electrode current collector 10
20 such as an aluminum (Al) foil to form a positive electrode active material layer 20,
manufacturing a positive electrode sheet 30, and punching a positive electrode plate 40 to a
predetermined size. The leftover after punching is discarded as positive electrode scrap 50.
If the positive electrode active material is collected and reused from the positive electrode
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scrap 50, it will be very desirable in the industrial-economic and environmental aspects.
Most of the existing methods of collecting the positive electrode active material
include dissolving the positive electrode with hydrochloric acid, sulfuric acid, nitric acid or
the like, extracting the active material elements such as cobalt, nickel and manganese and
5 using them as raw materials for the positive electrode active material synthesis. However,
the active material element extraction using acids uses a non-eco-friendly process to collect
pure raw materials, and needs a neutralization process and a waste water treatment process,
resulting in the increased process cost. Additionally, it is impossible to collect lithium, one
of the key positive electrode active material elements. To overcome these disadvantages,
10 there is a need for a direct reuse method that does not dissolve the positive electrode active
material and does not extract the active material in the form of an element.

WHAT IS CLAIMED IS:
1. A positive electrode active material reuse method, comprising:
(a) thermally treating positive electrode scrap comprising a lithium composition
5 transition metal oxide positive electrode active material layer on a current collector in air for
thermal decomposition of a binder and a conductive material in the active material layer, to
separate the current collector from the active material layer, and collecting an active material
in the active material layer;
(b-1) washing the collected active material with a lithium compound solution which
10 is basic in an aqueous solution, and drying;
(b-2) grinding the dried active material;
(b-3) adding a lithium precursor to the ground active material; and
(c) annealing the active material having the lithium precursor added thereto, to
obtain a reusable active material.
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2. The positive electrode active material reuse method according to claim 1,
further comprising:
(d) surface-coating the annealed active material.
20 3. The positive electrode active material reuse method according to claim 1,
wherein the lithium composite transition metal oxide comprises secondary particles formed
by agglomeration of primary particles having a size of a few of tens to a few of hundreds of
nm, and the grinding comprises reducing the size of the dried active material to a particle
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size that is larger than the size of the primary particles.
4. The positive electrode active material reuse method according to claim 3,
wherein the lithium composite transition metal oxide comprises nickel, cobalt and
5 manganese.
5. The positive electrode active material reuse method according to claim 1,
wherein the thermal treatment is performed at 300 to 650℃.
10 6. The positive electrode active material reuse method according to claim 1,
wherein the lithium compound solution contains a lithium compound in an amount of more
than 0% and 15% or less, and the washing is performed within 1 hour.
7. The positive electrode active material reuse method according to claim 1,
15 wherein the washing is performed by stirring the collected active material at the same time
with immersing in the lithium compound solution.
8. The positive electrode active material reuse method according to claim 1,
wherein the grinding is performed using a ball mill, a planetary mill, a grinder, a 3-roll mill
20 or a jet mill.