WO2020071640A1

WO2020071640A1 - Method and system for regenerating lithium precursor

Info

Publication number: WO2020071640A1
Application number: PCT/KR2019/010914
Authority: WO
Inventors: 나지예; 구민수
Original assignee: 에스케이이노베이션 주식회사
Priority date: 2018-10-04
Filing date: 2019-08-27
Publication date: 2020-04-09
Also published as: KR101998691B1

Abstract

A method for regenerating a lithium precursor according to embodiments of the present invention comprises: supplying, to a continuous flow reactor, a cathode active material mixture collected from a waste lithium secondary battery; introducing a fluid into the continuous flow reactor to produce a counter flow; bringing the counter flow into contact with the cathode active material mixture to produce a lithium precursor aqueous solution; and collecting a lithium precursor from the lithium precursor aqueous solution. The present invention can improve the yield and efficiency of lithium precursor regeneration through a continuous contact reaction with the counter flow.

Description

Lithium precursor regeneration method and lithium precursor regeneration system

The present invention relates to a lithium precursor regeneration method and a lithium precursor regeneration system. More particularly, it relates to a method and system for regenerating a lithium precursor from a waste lithium secondary battery.

The secondary battery is a battery that can be repeatedly charged and discharged, and has been widely applied to portable electronic communication devices such as camcorders, mobile phones, notebook PCs, etc. with the development of the information communication and display industries. Examples of the secondary battery include lithium secondary batteries, nickel-cadmium batteries, and nickel-hydrogen batteries, among which lithium secondary batteries have high operating voltage and energy density per unit weight, and are advantageous for charging speed and weight reduction. In this regard, it has been actively developed and applied.

The lithium secondary battery may include an electrode assembly including a positive electrode, a negative electrode, and a separator (separator), and an electrolyte impregnating the electrode assembly. The lithium secondary battery may further include, for example, a pouch-shaped exterior material that accommodates the electrode assembly and the electrolyte.

Lithium metal oxide may be used as the positive electrode active material of the lithium secondary battery. The lithium metal oxide may additionally contain transition metals such as nickel, cobalt, and manganese.

Lithium metal oxide as the positive electrode active material may be prepared by reacting a lithium precursor and a nickel-cobalt-manganese (NCM) precursor containing nickel, cobalt, and manganese.

As the expensive metals described above are used for the positive electrode active material, 20% or more of the manufacturing cost is required to manufacture the positive electrode material. In addition, as environmental protection issues have recently emerged, research on the recycling method of the positive electrode active material has been conducted. In order to recycle the positive electrode active material, it is necessary to recycle the lithium precursor from the waste positive electrode with high efficiency and high purity.

For example, Korean Patent Publication No. 2015-0002963 discloses a method for recovering lithium using a wet method. However, since lithium is recovered by wet extraction from the remaining waste liquid after extracting cobalt, nickel, and the like, the recovery rate is excessively reduced, and many impurities may be generated from the waste liquid.

One object of the present invention is to provide a method for regenerating a lithium precursor with high efficiency and high yield.

One object of the present invention is to provide a system for regenerating a lithium precursor with high efficiency and high yield.

In the lithium precursor regeneration method according to the exemplary embodiments, the positive electrode active material mixture collected from the waste lithium secondary battery is supplied to a continuous flow reactor. Fluid is introduced into the continuous flow reactor to produce a counter flow. A lithium precursor aqueous solution is produced by contacting the counter flow and the positive electrode active material mixture. The lithium precursor is collected from the aqueous lithium precursor solution.

In some embodiments, the fluid may be supplied to the bottom of the continuous flow reactor rather than the positive electrode active material mixture to generate a counter flow.

In some embodiments, in generating the aqueous lithium precursor solution, a plurality of impellers continuously arranged in the longitudinal direction of the continuous flow reactor may be rotated.

In some embodiments, in generating the aqueous solution of the lithium precursor, the flow of the counter flow may be maintained through a porous plate disposed between the impellers in the continuous flow reactor.

In some embodiments, a plurality of the continuous flow reactors are continuously arranged and a counter flow can be generated within each continuous flow reactor.

In some embodiments, the positive electrode active material mixture may sequentially pass through a plurality of the continuous flow reactors.

In some embodiments, in collecting the lithium precursor, the aqueous lithium precursor solution may be stabilized at the top of the continuous flow reactor. The lithium precursor aqueous solution may be crystallized to regenerate the lithium precursor.

In some embodiments, the positive electrode active material mixture may include a preliminary lithium precursor and a transition metal-containing mixture.

In some embodiments, a transition metal precursor can be collected from the transition metal containing mixture.

In some embodiments, in collecting the transition metal precursor, the transition metal containing mixture may be collected from the bottom of the continuous flow reactor. The transition metal-containing mixture can be treated with an acid solution.

In some embodiments, the transition metal-containing mixture may be flushed in collecting the transition metal-containing mixture.

In some embodiments, the preliminary lithium precursor may include lithium hydroxide, lithium oxide and lithium carbonate.

In some embodiments, the lithium precursor may include lithium hydroxide.

In some embodiments, the positive electrode active material mixture may be produced by reducing a waste positive electrode active material.

The lithium precursor regeneration system according to the exemplary embodiments includes a positive electrode active material mixture introduction part, a continuous flow reactor for hydrating a positive electrode active material mixture supplied from the positive electrode active material mixture contact with a counter flow, and the positive electrode active material reacted with the counter flow. And a lithium precursor collection section for generating a lithium precursor from the mixture.

In some embodiments, the continuous flow reactor may include a plurality of impellers arranged in the longitudinal direction of the continuous flow reactor, and at least one porous plate disposed between the impellers.

In some embodiments, the impellers may include a first impeller and a second impeller disposed non-parallel to each other.

In some embodiments, a plurality of continuous flow reactors can be arranged continuously.

According to the exemplary embodiments described above, for example, a lithium precursor in the form of lithium hydroxide may be regenerated through a contact reaction between a positive electrode active material mixture and a counter flow of a fluid. Therefore, it is possible to increase the contact time between the positive electrode active material mixture and the fluid to improve the lithium precursor regeneration yield, and to reduce the amount of fluid used.

In addition, by utilizing a continuous process using a continuous flow reactor it is possible to significantly increase the reaction rate and regeneration yield compared to the batch (batch) method.

1 is a process flow diagram illustrating a lithium precursor regeneration method according to example embodiments.

2 is a schematic schematic diagram for describing a lithium precursor regeneration system according to example embodiments.

3 is a perspective view for explaining the structure of the impeller and the porous plate according to the exemplary embodiments.

4 is a schematic diagram illustrating an impeller according to some example embodiments.

5 to 7 are simulation graphs for explaining the lithium precursor regeneration yield using a continuous flow reactor and a batch reactor.

Embodiments of the present invention provide a method and system for regenerating a lithium precursor with high purity and high yield from a waste lithium secondary battery, for example, through a continuous flow reactor.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, this is merely exemplary and the present invention is not limited to the specific exemplary embodiments.

As used herein, the term "precursor" is used to generically refer to a compound containing the specific metal to provide a specific metal included in the electrode active material.

1 is a process flow diagram illustrating a lithium precursor regeneration method according to example embodiments. 2 is a schematic schematic diagram for describing a lithium precursor regeneration system according to example embodiments.

Hereinafter, referring to FIGS. 1 and 2, a method and system for regenerating a lithium precursor will be described together.

1, a positive electrode active material mixture may be prepared (for example, step S10). According to exemplary embodiments, the positive electrode active material mixture may be obtained from a waste lithium-containing compound obtained from a waste lithium secondary battery.

The waste lithium secondary battery may include an electrode assembly including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode. The positive electrode and the negative electrode may include a positive electrode active material layer and a negative electrode active material layer coated on the positive electrode current collector and the negative electrode current collector, respectively.

For example, the positive electrode active material included in the positive electrode active material layer may include an oxide containing lithium and a transition metal.

In some embodiments, the positive electrode active material may include a compound represented by Formula 1 below.

[Formula 1]

Li _x M1 _a M2 _b M3 _c O _y

In Formula 1, M1, M2 and M3 are transition metals selected from Ni, Co, Mn, Na, Mg, Ca, Ti, V, Cr, Cu, Zn, Ge, Sr, Ag, Ba, Zr, Nb, Mo, Al, Ga or B Can be In

Formula

1, 0 <x≤1.1, 2≤y≤2.02, 0 <a <1, 0 <b <1, 0 <c <1, 0 <a + b + c≤1.

In some embodiments, the positive electrode active material may be NCM-based lithium oxide including nickel, cobalt, and manganese. NCM-based lithium oxide as the positive electrode active material may be prepared by reacting a lithium precursor and an NCM precursor (eg, NCM oxide) with each other through, for example, a co-precipitation reaction.

However, the embodiments of the present invention can be commonly applied to a positive electrode material containing the NCM-based lithium oxide, as well as a lithium-containing positive electrode material.

The lithium precursor may include lithium hydroxide (LiOH), lithium oxide (Li ₂ O), or lithium carbonate (Li ₂ CO ₃ ). Lithium hydroxide may be advantageous as a lithium precursor in terms of charging / discharging characteristics, life characteristics, and high temperature stability of the lithium secondary battery. For example, in the case of lithium carbonate, a deposition reaction may be caused on the separator to weaken life stability.

Accordingly, according to embodiments of the present invention, a method of regenerating lithium hydroxide as a lithium precursor at a high selectivity may be provided.

For example, the positive electrode can be recovered by separating the positive electrode from the waste lithium secondary battery. The positive electrode includes a positive electrode current collector (for example, aluminum (Al)) and a positive electrode active material layer as described above, and the positive electrode active material layer may include a conductive material and a binder together with the positive electrode active material described above. .

The conductive material may include, for example, carbon-based materials such as graphite, carbon black, graphene, and carbon nanotubes. The binder is, for example, vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylidene fluoride (PVDF), polyacrylonitrile (polyacrylonitrile), polymethyl methacrylate and resin materials such as (polymethylmethacrylate).

A preliminary positive electrode active material mixture may be prepared from the recovered positive electrode. In some embodiments, the preliminary positive electrode active material mixture may be prepared in powder form through a physical method such as grinding treatment. The preliminary positive electrode active material mixture includes a powder of a lithium-transition metal oxide, for example, NCM-based lithium oxide powder (eg, Li (NCM) O ₂ ).

In some embodiments, the anode recovered before the crushing treatment may be heat treated. Accordingly, desorption of the positive electrode current collector during the pulverization treatment may be promoted, and the binder and the conductive material may be at least partially removed. The heat treatment temperature may be performed at, for example, about 100 to 500 ° C, preferably about 350 to 450 ° C.

In some embodiments, the preliminary positive electrode active material mixture may be obtained after immersing the recovered positive electrode in an organic solvent. For example, the positive electrode current collector may be separated and removed by immersing the recovered positive electrode in an organic solvent, and the positive electrode active material may be selectively extracted through centrifugation.

Through the above-described processes, the positive electrode current collector component such as aluminum is substantially completely separated and removed, and the preliminary positive electrode active material mixture having the content of carbon-based components derived from the conductive material and the binder removed or reduced can be obtained. .

In some embodiments, the preliminary positive electrode active material mixture (eg, waste positive electrode active material) may be reduced to generate the positive electrode active material mixture. For example, the preliminary positive electrode active material mixture may be hydrogen-reduced to form a positive electrode active material mixture.

The positive electrode active material mixture may include a hydrogen reduction reaction of a lithium-transition metal oxide contained in the preliminary positive electrode active material mixture. When an NCM-based lithium oxide is used as the lithium-transition metal oxide, the preliminary precursor mixture may include a preliminary lithium precursor and a transition metal-containing mixture.

The preliminary lithium precursor may include lithium hydroxide, lithium oxide and / or lithium carbonate. According to exemplary embodiments, since the preliminary lithium precursor is obtained through a hydrogen reduction reaction, the mixed content of lithium carbonate may be reduced.

The transition metal-containing reactant may include Ni, Co, NiO, CoO, MnO, and the like.

1 and 2 together, the positive electrode active material mixture may be introduced into a continuous flow reactor (eg, CSTR) 100 (eg, step S20).

The continuous flow reactor 100 may be connected to a first flow path 102a provided as a supply portion of the positive electrode active material mixture. In addition, the continuous flow reactor 100 may be connected to a second flow path 102b provided as a counter flow forming fluid supply unit, which will be described later.

For example, pure water may be supplied through the second flow path 102b to generate a counter flow in the reactor body 130.

In example embodiments, the first flow path 102a may be disposed above the continuous flow reactor 100 than the second flow path 102b. As described above, the positive electrode active material mixture may be supplied through the first flow path 102a disposed on the second flow path 102b. For example, a positive electrode active material mixture having a higher density is supplied to the first flow path 102a disposed above the continuous flow reactor 100 than the second flow path 102b, and disposed at the lower portion of the continuous flow reactor 100. A fluid having a low density is supplied to the second flow path 102b, and a counter flow (countercurrent, flow) may be formed by a difference in density between the positive electrode active material mixture and the fluid.

Accordingly, the positive electrode active material mixture is in contact with the counter flow rising from the bottom to the top of the reactor body 130, a hydration reaction may be induced. Accordingly, an aqueous lithium precursor solution may be generated (eg, step S30).

The continuous flow reactor 100 may include a reactor body 130 and a plurality of impellers 110 included inside the reactor body 130. The impellers 110, for example, share one rotating shaft 115 and may be continuously disposed along the longitudinal direction of the reactor body 130.

In some embodiments, at least one porous plate 120 may be disposed between the impellers 110.

The counter flow may continuously rise through a fluid continuously supplied through the second flow path 102b. Therefore, the time during which the positive electrode active material mixture stays in the reactor body 130 and the hydration reaction can be increased can improve the regeneration yield.

In addition, a plurality of impellers continuously arranged in the longitudinal direction of the continuous flow reactor 100 may be rotated. Therefore, the contact efficiency between the positive electrode active material mixture and the counter flow increases due to the rotation of the impellers, thereby improving the production efficiency of the lithium precursor aqueous solution.

In addition, since the porous plate 120 is disposed between the impellers 110, the counter flow is prevented from flowing backward or turbulence, and the rise of the counter flow can be maintained. Therefore, since the contact time between the positive electrode active material mixture and the counter flow is increased, the regeneration yield of the lithium precursor through the hydration reaction may be further improved. In addition, it is possible to reduce the amount of fluid for maintaining the counter flow rise.

As described above, the positive electrode active material mixture may include a preliminary lithium precursor and a transition metal-containing mixture 70. The preliminary lithium precursor may be converted into a lithium precursor 60 containing lithium hydroxide by hydration reaction through contact with the counter flow.

For example, lithium oxide and lithium carbonate contained in the preliminary lithium precursor may be converted into lithium hydroxide. According to exemplary embodiments, the lithium precursor 60 may be substantially composed of lithium hydroxide through continuous reaction with the counter flow.

The lithium precursor 60 may be substantially dissolved in the counter flow containing water to rise together with the counter flow in the form of an aqueous solution. The transition metal-containing mixture 70 remains in a solid state and may move to the bottom of the reactor 100 by gravity. For example, the transition metal-containing mixture 70 may settle to the bottom of the reactor 100 through pores included in the porous plate 120.

Accordingly, as illustrated in FIG. 2, a distribution gradient of the lithium precursor 60 and the transition metal-containing mixture 70 may be formed inside the reactor body 130. According to exemplary embodiments, the distribution density of the lithium precursor 60 may be increased toward the upper portion of the reactor body 130.

In some embodiments, a plurality of continuous flow reactors 100 may be continuously arranged. In this case, a counter flow is generated in each continuous flow reactor 100, and the positive electrode active material mixture sequentially passes through a plurality of continuous flow reactors and is in continuous contact with the counter flow to induce a hydration reaction. Therefore, the conversion rate of the preliminary lithium precursor to lithium hydroxide can reach substantially 100%. In addition, since the transition metal-containing mixture is collected from each continuous flow reactor 100, the resolution and yield of the transition metal-containing mixture can also be improved.

In one embodiment, the reactor body 130 includes a temperature-adjustable heater, and for the hydration reaction efficiency, the temperature inside the reactor body 130 may be maintained within a range of about 30 to 95 ^° C.

Referring back to FIGS. 1 and 2, a lithium precursor and a transition metal precursor may be collected from the reactor body 130 (eg, step S40).

According to exemplary embodiments, the lithium precursor 60 may be recovered from the lithium precursor collection unit 150 connected to the upper portion of the reactor body 130. The lithium precursor collection unit 150 may be provided as a stabilization unit of a lithium precursor aqueous solution.

For example, the lithium precursor aqueous solution stays or circulates in the lithium precursor collection unit 150, and the transition metal-containing mixture 70 mixed in the lithium precursor aqueous solution is separated and removed under the reactor body 130. You can.

For sufficient stabilization of the lithium precursor aqueous solution, the lithium precursor collection unit 150 may have a larger diameter or cross-sectional area than the reactor body 100. Therefore, since the flow rate in the lithium precursor collection unit 150 of the lithium precursor aqueous solution decreases, the high-density transition metal-containing mixture precipitates, so that the high-purity lithium precursor can be easily collected.

For example, the lithium precursor 60 collected in the lithium precursor collection unit 150 may be recovered through the first recovery channel 160a. Thereafter, the lithium precursor in the form of lithium hydroxide may be regenerated through a crystallization process or the like.

According to exemplary embodiments, the transition metal-containing mixture 70 may be collected through the transition metal precursor collection unit 140.

As described above, the transition metal-containing mixture 70 may not be dissolved in the counter flow and may be precipitated in the transition metal precursor collection unit 140 through the porous plate 120 in a solid form.

In some embodiments, the transition metal precursor collection unit 140 may be provided as a flushing or flushing section. For example, lithium or a lithium precursor remaining on the surface of the transition metal-containing mixture 70 may be washed with water by supplying water from the bottom of the reactor body 130. Accordingly, the substantially pure transition metal-containing mixture 70 may be collected in the transition metal precursor collection unit 140.

The transition metal-containing mixture 70 may be recovered through the second recovery channel 160b. In some embodiments, the recovered transition metal-containing mixture 70 may be acid treated through a filtration or separation process. Accordingly, transition metal precursors in the acid salt form of each transition metal can be formed.

In one embodiment, sulfuric acid may be used as the acid treatment solution. In this case, NiSO ₄ , MnSO ₄ and CoSO ₄ may be recovered as the transition metal precursor, respectively.

As described above, the purity and recovery rate of the lithium precursor may be increased through a distribution gradient utilizing the column type continuous flow reactor 100. In addition, the lithium precursor in the form of lithium hydroxide can be obtained in high yield with a small amount of water through a continuous hydration reaction using a counter flow.

Referring to FIG. 3, as described above, a plurality of impellers 110 may be arranged along the rotation axis 115 extending in the longitudinal direction of the reactor body 130. A porous plate 120 may be disposed between the impellers 110.

Each impeller 110 may include a plurality of blades. For example, the four blades may be arranged around the rotation axis 115 such that they intersect at right angles to each other.

The blade arrangement shown in FIG. 3 is exemplary, and may be appropriately modified according to the shape of the reactor body 130.

4, impellers may be arranged non-parallel to each other. For example, the impeller may include a first impeller 110a and a second impeller 110b.

In some embodiments, the plurality of first impellers 110a and the second impellers 110b may be alternately arranged alternately along the rotation axis 115.

The blades of the first impeller 110a and the second impeller 110b may be disposed non-parallel to each other. For example, the first impeller 110a may be disposed substantially perpendicular to the rotating shaft 115, and the second impeller 110b may be disposed obliquely to the rotating shaft 115.

For example, by including the inclined second impeller 110b, it is possible to more effectively prevent the drop of the counter flow and promote dispersion of the counter flow inside the reactor body 130.

5 to 7 are simulation graphs for explaining lithium precursor regeneration yield using a continuous flow reactor (CSTR) and a batch reactor.

5 to 7, the x-axis represents the reactor residence time (hr) of the positive electrode active material mixture, and the y-axis represents the yield (LiOH Yield) of the lithium precursor.

5 is a graph showing a change in yield of lithium precursors according to an increase in the dissolution rate constant of a CSTR compared to a batch reactor. The dissolution rate constant refers to the rate at which LiOH dissolves in water, and is proportional to the dissolution concentration and the contact area with water.

Referring to FIG. 5, it can be seen that as the dissolution rate constant increases in the CSTR compared to the batch reactor, the residence time decreases until a yield of 1 is reached.

6 is a graph showing a change in the yield of lithium precursors according to the number of CSTRs or the number of counter flows, assuming that the dissolution rate constant of the CSTR is 2 times that of a batch reactor.

Referring to FIG. 6, it can be seen that as the number of counter flows through the CSTR increases, the residence time reaching the yield 1 decreases.

7 is a graph showing a change in the yield of a lithium precursor according to a flow rate change, assuming that the dissolution rate constant of the CSTR is 2 times that of the batch reactor and the number of CSTRs is 4.

Referring to FIG. 7, it can be seen that a yield substantially equal to 1/10 of the flow rate used in the batch reactor is secured, and a yield of 0.8 or higher is secured to 1/40 of the flow rate of the batch reactor.

Referring to the simulation results of FIGS. 5 to 7, it can be confirmed that a yield close to 100% can be secured with a small counter flow flow rate by utilizing a CSTR system having an excellent dissolution rate constant. In addition, it can be seen that the lithium precursor conversion efficiency is further improved by continuously providing a counter flow utilizing a plurality of CSTRs.

Claims

Supplying the positive electrode active material mixture collected from the waste lithium secondary battery to a continuous flow reactor;

Introducing a fluid into the continuous flow reactor to produce a counter flow;

Generating a lithium precursor aqueous solution by contacting the counter flow and the positive electrode active material mixture; And

And collecting the lithium precursor from the lithium precursor aqueous solution.
The method according to claim 1, The step of generating the counter flow comprises supplying the fluid to the lower portion of the continuous flow reactor than the positive electrode active material mixture, lithium precursor regeneration method.
The method according to claim 1, The step of generating the aqueous solution of lithium precursor comprises rotating a plurality of impellers arranged in the longitudinal direction of the continuous flow reactor, lithium precursor regeneration method.
The method according to claim 3, wherein the step of generating the aqueous solution of lithium precursor comprises maintaining the flow of the counter flow through a porous plate disposed between the impellers in the continuous flow reactor.
The method according to claim 1, A plurality of said continuous flow reactors are arranged continuously and a counter flow is generated in each continuous flow reactor.
The method according to claim 5, The positive electrode active material mixture is a lithium precursor regeneration method, sequentially passing through a plurality of the continuous flow reactors.
The method according to claim 1, The step of collecting the lithium precursor,

Stabilizing the aqueous lithium precursor solution at the top of the continuous flow reactor; And

And regenerating the lithium precursor by crystallizing the aqueous lithium precursor solution.
The method according to claim 1, The positive electrode active material mixture comprises a preliminary lithium precursor and a transition metal-containing mixture, lithium precursor regeneration method.
The method of claim 8, further comprising collecting a transition metal precursor from the transition metal-containing mixture.
The method according to claim 9, The step of collecting the transition metal precursor,

Collecting the transition metal containing mixture from the bottom of the continuous flow reactor; And

And treating the transition metal-containing mixture with an acid solution.
The method of claim 10, wherein collecting the transition metal-containing mixture comprises flushing the transition metal-containing mixture.
The method of claim 8, wherein the preliminary lithium precursor comprises lithium hydroxide, lithium oxide and lithium carbonate.
The method according to claim 1, The lithium precursor comprises a lithium hydroxide, lithium precursor regeneration method.
The method according to claim 1, The positive electrode active material mixture is produced by reducing the waste positive electrode active material, lithium precursor regeneration method.
A cathode active material mixture introduction part;

A continuous flow reactor for hydrating the positive electrode active material mixture supplied from the positive electrode active material mixture introduction unit by contacting it with a counter flow; And

And a lithium precursor collection unit for generating a lithium precursor from the positive electrode active material mixture reacted with the counter flow.
The method according to claim 15, wherein the continuous flow reactor,

A plurality of impellers arranged in the longitudinal direction of the continuous flow reactor; And

And at least one porous plate disposed between the impellers.
17. The lithium precursor regeneration system of claim 16, wherein the impellers include a first impeller and a second impeller disposed non-parallel to each other.
The lithium precursor regeneration system of claim 15, wherein the lithium precursor collection unit has a larger diameter than the continuous flow reactor.
16. The lithium precursor regeneration system of claim 15, wherein a plurality of continuous flow reactors are continuously disposed.