TECHNICAL FIELD
The present disclosure relates to a method of recycling resources when
manufacturing a lithium secondary battery. In particular, the present disclosure relates to
an apparatus for recovering an electrode active material from an electrode scrap generated
10 in a lithium secondary battery manufacturing process or from a lithium secondary battery
that is discarded after use, and a method of reusing the recovered active material. The present
application claims priority to Korean Patent Application No. 10-2020-0106079 filed on
August 24, 2020 in the Republic of Korea, the disclosure of which is incorporated herein by
reference.
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BACKGROUND ART
Lithium secondary batteries which may be repeatedly charged and discharged are in
the spotlight as an alternative to fossil energy. Lithium secondary batteries have been
mainly used in traditional handheld devices such as cell phones, video cameras, and power
20 tools. However, recently, application fields of lithium secondary batteries have been
gradually increasing to electric vehicles (EVs, HEVs, and PHEVs), large capacity energy
storage systems (ESSs), uninterruptible power supply systems (UPS), etc.
A lithium secondary battery includes an electrode assembly in which unit cells
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having a structure in which a positive electrode plate and a negative electrode plate coated
with an active material on a current collector are arranged with a separator interposed
therebetween, and an exterior material sealing and accommodating the electrode assembly
together with an electrolyte, that is, a battery case. The positive electrode active material
5 of the lithium secondary battery mainly uses a lithium-based oxide, and the negative
electrode active material uses a carbon material. The lithium-based oxide contains a metal
such as cobalt, nickel, or manganese. In particular, cobalt, nickel, and manganese are very
expensive valuable metals. Among these, cobalt is a strategic metal, and each country in
the world has a special interest in supply and demand of cobalt. Since the number of cobalt
10 producing countries is limited, it is known as a metal whose supply and demand is unstable
worldwide. If an imbalance in the supply and demand of raw materials of strategic metals
occurs, raw material prices are highly likely to rise.
Conventionally, research on recovering and recycling these valuable metals from
lithium secondary batteries (waste batteries) which are discarded when their lifespan is
15 completed after use has been mainly conducted. In addition to waste batteries, it is more
preferable if resources may be recovered from wastes discarded after the positive electrode
plate is punched or from the positive electrode in which a defect occurs during the process.
Currently, when manufacturing a lithium secondary battery, as shown in FIG. 1, a
positive electrode sheet 30 is manufactured by forming a positive electrode active material
20 layer 20 in which a long sheet type positive electrode current collector 10 such as aluminum
(Al) foil is coated with a positive electrode slurry in which a positive electrode active
material, a conductive material, a binder, a solvent, etc. are mixed, and then a positive
electrode plate 40 is punched out with a certain size. A part remaining after punching is
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discarded as a positive electrode scrap 50. If it is possible to recover the positive electrode
active material from the positive electrode scrap 50 and reuse the positive electrode active
material, it would be very desirable from an industrial-economic point of view and an
environmental point of view.

WHAT IS CLAIMED IS:
1. An active material recovery apparatus which is a rotary firing apparatus, the
active material recovery apparatus comprising:
5 a heat treatment bath and a screening wall arranged in a line along one axis, wherein
the heat treatment bath constitutes a heating zone, and the screening wall constitutes a
cooling zone; and
an exhaust injection and degassing system,
wherein the heat treatment bath removes a binder and a conductive material in an
10 active material layer by performing heat treatment in air on an electrode scrap comprising
the active material layer on a current collector while rotating the electrode scrap around an
axis and separates the current collector from the active material layer,
an active material in the active material layer passes through the screening wall and
is recovered as an active material in powder form, and the current collector that does not
15 pass through the screening wall is recovered separately, and
irregularities in a sawtooth shape are formed inside of the heat treatment bath on a
cross-section orthogonal to the axis.
2. The active material recovery apparatus of claim 1, wherein a rod of a screw
20 type is provided as the one axis at a center of the heat treatment bath and the cooling zone,
and the rod rotates.
3. The active material recovery apparatus of claim 1, wherein the irregularities
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are continuous or discontinuous along the axis.
4. The active material recovery apparatus of claim 1, wherein irregularities in a
sawtooth shape are formed inside of the screening wall on a cross-section orthogonal to the
5 axis.
5. The active material recovery apparatus of claim 4, wherein the irregularities
are continuous or discontinuous along the axis.
10 6. The active material recovery apparatus of claim 1, wherein air inlets are
formed in a plurality of places in the heat treatment bath.
7. The active material recovery apparatus of claim 2, wherein air inlets are
formed in the irregularities and the rod.
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8. The active material recovery apparatus of claim 2, wherein the heat treatment
bath also rotates around the rod.
9. The active material recovery apparatus of claim 1, wherein an angle of the
20 entire active material recovery apparatus is adjusted such that the axis is inclined with respect
to a ground.
10. The active material recovery apparatus of claim 1, wherein the active material
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recovery apparatus has a vibration function.
11. The active material recovery apparatus of claim 1, wherein input of a new
electrode scrap and recovery of the active material are continuously performed.
5
12. The active material recovery apparatus of claim 1, wherein the heat treatment
bath has a tubular shape with both ends open so that the electrode scrap is put therein and
the separated current collector and active material are transferred to the screening wall, and
a tube is an open type system through which air enters and exits.
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13. The active material recovery apparatus of claim 12, wherein the screening
wall has a tubular shape with both ends open so that the separated current collector and active
material are put therein and the current collector is discharged.
15 14. The active material recovery apparatus of claim 1, wherein the heat treatment
bath is an open type system in which air of 10 mL/min to 100 L/min is added or injected per
100 g of the electrode scrap that is put in.
15. A positive electrode active material reuse method comprising:
20 preparing an active material recovery apparatus according to any one of claims 1 to
14;
putting a positive electrode scrap in a heat treatment bath, the positive electrode
scrap comprising a lithium composite transition metal oxide positive electrode active
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material layer on a current collector;
removing a binder and the conductive material in an active material layer by
performing heat treatment in air on the positive electrode scrap while rotating the positive
electrode scrap around an axis in the heat treatment bath, and separating the current collector
5 from the active material layer;
recovering an active material in powder form that has passed through a screening
wall; and
annealing the active material in the air at 400 to 1000 °C to obtain a reusable active
material.
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16. The positive electrode active material reuse method of claim 15, wherein the
heat treatment is performed at 300 to 650 ℃.
17. The positive electrode active material reuse method of claim 15, further
15 comprising, before the annealing, cleaning the recovered active material with a lithium
compound solution showing basicity in an aqueous solution state.
18. The positive electrode active material reuse method of claim 17, wherein,
before the annealing, a lithium precursor is added to the cleaned active material.
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19. The positive electrode active material reuse method of claim 17, further
comprising, after the cleaning, obtaining the active material to which a lithium precursor is
added and of which particles are adjusted, by mixing the cleaned active material with a
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lithium precursor solution and spray drying the active material.
20. The positive electrode active material reuse method of claim 15, further
comprising performing surface coating on the annealed active material