WO2025204167A1 - Method and system for processing waste lithium ion battery - Google Patents

Abstract

This method for processing a waste lithium ion battery for recovering lithium from a waste lithium ion battery that contains fluorine includes: introducing a roasted material that is obtained by roasting the waste lithium ion battery into a first dissolution tank so as to immerse the roasted material in water; performing first solid-liquid separation on the aqueous solution after immersion in the first dissolution tank; recovering the lithium from the aqueous solution that is separated by the first solid-liquid separation; introducing the residue after immersion in the first dissolution tank into a second dissolution tank, which is different from the first dissolution tank, so as to immerse the residue in water; adding calcium hydroxide to water in the second dissolution tank; performing second solid-liquid separation on the aqueous solution after immersion in the second dissolution tank; and separating excess calcium, which is derived from calcium hydroxide, and lithium from the aqueous solution that is separated by the second solid-liquid separation.

Description

Method and system for treating waste lithium-ion batteries

This disclosure relates to a method and system for processing waste lithium-ion batteries.

In order to recover the lithium contained in lithium-ion batteries, waste lithium-ion batteries are roasted, and the roasted material is immersed in water to dissolve the lithium ions in the water, separating the lithium from impurities.

However, lithium-ion batteries contain large amounts of fluorine in the electrolyte, binder, etc., and there is a concern that when used lithium-ion batteries are roasted, lithium ions and fluorine ions may combine to produce lithium fluoride. Because lithium fluoride is poorly soluble in water, if it is discarded as residue, the lithium recovery rate will decrease.

Patent Document 1 below describes adding calcium hydroxide to a lithium solution containing fluorine and lithium in order to separate lithium from the solution.

International Publication No. 2021/090571

However, even if calcium hydroxide is added to the dissolution tank in which the roasted material is immersed in water, the lithium fluoride does not actually dissolve, and the fluorine and lithium cannot be separated.

The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a method and system for processing waste lithium-ion batteries that can promote the dissolution of lithium fluoride and increase the lithium recovery rate.

A method for treating used lithium-ion batteries according to one embodiment of the present disclosure is a method for recovering lithium from used lithium-ion batteries containing fluorine, comprising: introducing a roasted product obtained by roasting the used lithium-ion batteries into a first dissolving tank and immersing it in water; performing a first solid-liquid separation on the aqueous solution resulting from immersion in the first dissolving tank; recovering the lithium from the aqueous solution separated by the first solid-liquid separation; introducing the residue resulting from immersion in the first dissolving tank into a second dissolving tank different from the first dissolving tank and immersing it in water; adding calcium hydroxide to the water in the second dissolving tank; performing a second solid-liquid separation on the aqueous solution resulting from immersion in the second dissolving tank; and separating excess calcium derived from the calcium hydroxide and the lithium from the aqueous solution separated by the second solid-liquid separation.

Furthermore, a waste lithium-ion battery treatment system according to another aspect of the present disclosure is a waste lithium-ion battery treatment system for recovering lithium from waste lithium-ion batteries containing fluorine, and includes: a first dissolving tank into which roasted material obtained by roasting the waste lithium-ion batteries is introduced and immersed in water; a first separator that performs a first solid-liquid separation on the aqueous solution after immersion in the first dissolving tank; a lithium recovery device that recovers the lithium from the aqueous solution separated by the first separator; a second dissolving tank different from the first dissolving tank that introduces and immerses the residue after immersion in the first dissolving tank in water to which calcium hydroxide is added; a second separator that performs a second solid-liquid separation on the aqueous solution after immersion in the second dissolving tank; and a calcium separation device that separates excess calcium derived from the calcium hydroxide and the lithium from the aqueous solution separated by the second solid-liquid separation.

According to the present disclosure, it is possible to promote the dissolution of lithium fluoride and increase the lithium recovery rate.

FIG. 1 is a schematic process diagram showing the processing steps in a processing system for waste lithium ion batteries according to one embodiment of the present invention. FIG. 2 is a schematic diagram of a pyrolysis system for carrying out the pyrolysis step shown in FIG. FIG. 3 is a schematic diagram of a recovery system that performs the recovery process shown in FIG.

One embodiment will be described below with reference to the drawings. Figure 1 is a schematic diagram showing the processing steps in a processing system for used lithium-ion batteries in one embodiment of the present disclosure. Note that hereinafter, lithium-ion batteries may be abbreviated as LIBs.

The waste LIBs to be treated by the treatment system in this embodiment are, for example, NCM-type lithium-ion batteries, which contain nickel, cobalt, and manganese as the positive electrode active material. However, lithium-ion batteries other than NCM-type batteries may also be treated. A lithium-ion battery is a battery that contains graphite as the negative electrode active material, uses aluminum foil as the positive electrode current collector, and copper foil as the negative electrode current collector. Furthermore, a lithium-ion battery contains a fluorine compound as an electrolyte or binder.

This processing system targets large waste LIBs, i.e., battery modules made up of multiple waste LIB battery cells, and battery units made up of multiple battery modules. A battery unit, for example, is composed of multiple electrically connected battery modules, a control device, and a cooling device housed within a housing. This processing system is intended to remove waste LIBs installed in electric vehicles or hybrid vehicles, for example, and process the removed waste LIBs, i.e., battery units or battery modules, without dismantling them.

As shown in Figure 1, the processing system in this embodiment includes a thermal decomposition process P1 in which waste LIB is thermally decomposed and the resulting powder containing active material is roasted, and a recovery process P2 in which the roasted active material is immersed in water to elute the lithium, and then the lithium is recovered.

First, the pyrolysis process P1 will be described. The pyrolysis process P1 includes a pretreatment process P11, a crushing and sorting process P12, and a roasting process P13. Figure 2 is a schematic diagram of a pyrolysis system that performs the pyrolysis process shown in Figure 1. The pyrolysis system 1 includes a supply device 10, a pretreatment device 11, a crushing and sorting device 12, and a roasting device 13.

In the pre-treatment process P11, the waste LIB is roasted, i.e., pre-roasted, at a second temperature lower than the first temperature in the roasting process P13 described below in order to decompose and remove the electrolyte contained in the waste LIB. For this purpose, the waste LIB is supplied from the supply device 10 to the pre-treatment device 11. The supply device 10 is configured, for example, by a belt conveyor. The pre-treatment device 11 is configured, for example, by a grate preheater.

The second temperature in the pretreatment process P11 is set to a temperature at which the electrolyte contained in the waste LIB can be decomposed and removed. For example, the second temperature is equal to or higher than 150°C and lower than 400°C, and may be equal to or higher than 150°C and lower than 250°C.

The crushing and sorting process P12 crushes the waste LIBs processed in the pretreatment process P11, and separates the active material from the current collectors of the crushed waste LIBs to sort the active material. For this purpose, the crushing and sorting device 12 is equipped with a crusher 12a and a sorter 12b. The crusher 12a is configured, for example, by a roll crusher. The crusher 12a crushes large waste LIBs (battery units or battery modules) into pieces roughly the size of battery cells or smaller.

The sorter 12b is configured to separate the active material from the current collectors of the waste LIB crushed by the crusher 12a, and to sort and extract the active material. The sorter 12b is configured, for example, as a sieve shaker. In reality, the sorter 12b extracts not only the positive electrode active material, but also small amounts of impurities other than the active material, such as the negative electrode active material, and supplies them to the roasting device 13. Other waste LIB packaging materials, current collectors, etc. are sent to separate processing equipment.

In the roasting process P13, the waste LIB sorted in the crushing and sorting process P12 is roasted at a predetermined first temperature. The mixed waste LIB is a mixture containing the active material of the waste LIB and an alkali metal salt. The roasting device 13 is, for example, an externally heated rotary kiln. The externally heated rotary kiln has a cylinder 13a that rotates around its central axis and a heating jacket 13b that is arranged to surround the outer periphery of the cylinder 13a.

The cylindrical body 13a has an inlet 13c at one end and an outlet 13d at the other end, and is supported so that it can rotate around its central axis with the central axis inclined at a predetermined angle so that it slopes downward from the inlet 13c to the outlet 13d. The waste LIB supplied from the sorter 12b to the inlet 13c of the cylindrical body 13a is transported toward the outlet 13d as the cylindrical body 13a rotates.

The interior of the cylinder 13a is an air atmosphere. Alternatively, the interior of the cylinder 13a may be a reducing atmosphere or a low-oxygen atmosphere with an oxygen concentration of, for example, 10% or less. By supplying heated gas to the heating jacket 13b surrounding the outer periphery of the cylinder 13a, the outer wall of the cylinder 13a is heated, and the waste LIB transported inside the cylinder 13a is heated and discharged as roasted material from the discharge port 13d. The first temperature, which is the roasting temperature in the roasting process P13, is 400°C or higher and may be, for example, 800°C.

Next, the recovery process P2 will be described. Figure 3 is a schematic diagram of a recovery system that performs the recovery process shown in Figure 1. Recovery process P2 includes a first dissolution process P21, a first separation process P22, and a lithium recovery process P24. Correspondingly, recovery system 2 is equipped with a first dissolution tank 21, a first separator 22, and a lithium recovery device 24.

In the first dissolution process P21, the roasted material is immersed in water. For this purpose, water is stored in the first dissolution tank 21, and the roasted material is introduced into the first dissolution tank 21. The roasted material is supplied to the first dissolution tank 21 in predetermined amounts via a hopper 20. As a result, the aqueous solution in the first dissolution tank 21 becomes a mixture of water and the roasted material. The first dissolution tank 21 is equipped with a stirring mechanism that stirs the aqueous solution in the first dissolution tank 21.

Most of the lithium component contained in the roasted product is lithium carbonate (Li ₂ CO ₃ ) produced in the roasting step P13. The lithium carbonate dissolves in the water in the first dissolution tank 21.

The first separation process P22 performs a first solid-liquid separation on the aqueous solution treated in the first dissolution process P21. For this purpose, the first separator 22 is composed of a solid-liquid separator. By performing solid-liquid separation using the first separator 22, solid residue is removed from the aqueous solution. The lithium recovery process P24 recovers lithium from the aqueous solution separated in the first solid-liquid separation.

More specifically, the lithium recovery process P24 concentrates the aqueous solution separated in the first separation process P22. For this purpose, the lithium recovery device 24 may be equipped with a concentrator. The concentrator may be, for example, an evaporation/concentration device or crystallization device that heats the aqueous solution to 80°C or higher and evaporates the water content of the aqueous solution. By concentrating the aqueous solution, the concentration of lithium contained in the aqueous solution increases, and a slurry containing lithium carbonate is produced.

Furthermore, in the lithium recovery process P24, solid-liquid separation is performed on the produced slurry. For this purpose, the lithium recovery device 24 may be equipped with a solid-liquid separator. In the lithium recovery process P24, solid-liquid separation is performed, causing lithium carbonate to precipitate from the slurry. As a result, lithium is recovered as lithium carbonate. The remaining aqueous solution is subjected to waste liquid treatment. The remaining aqueous solution may be returned to the first dissolution tank 21 or the buffer tank 23 described below.

Here, the roasted material introduced into the first dissolving tank 21 contains lithium fluoride. As mentioned above, waste LIB contains fluorine, which combines with lithium during roasting, etc., to produce lithium fluoride (LiF). Lithium fluoride does not dissolve in water in the first dissolving tank 21 and is contained in the residue.

In this embodiment, the recovery process P2 includes a second dissolution process P25, a second separation process P26, and a calcium separation process P27. Correspondingly, the recovery system 2 is equipped with a second dissolution tank 25, a second separator 26, and a calcium separation device 27.

In the second dissolution process P25, the residue remaining after immersion in the first dissolution tank 21 is introduced into a second dissolution tank 25, which is different from the first dissolution tank 21, and immersed in water. For this purpose, the second dissolution tank 25 is configured to store new water and to receive the residue. The residue is supplied to the second dissolution tank 25 in predetermined amounts via a hopper 30. Furthermore, calcium hydroxide (Ca(OH) ₂ ) is added to the water in the second dissolution tank 25. As a result, the aqueous solution in the second dissolution tank 25 becomes a mixture of new water, the residue, and calcium hydroxide. The second dissolution tank 25 is equipped with a stirring mechanism for stirring the aqueous solution in the second dissolution tank 25.

In the second dissolution tank 25 into which water, residue, and calcium hydroxide are introduced, the following three reactions occur:
Ca(OH) ₂ →Ca ²⁺ +2OH ^-・・・(1)
LiF→Li ⁺ +F ^-... (2)
Ca ²⁺ +2F ^- →CaF ₂ ...(3)

That is, when calcium hydroxide is added to the water in the second dissolution tank 25, the calcium hydroxide dissolves in the water, generating calcium ions and hydroxide ions, as shown in reaction formula (1). When lithium fluoride contained in the residue in the second dissolution tank 25 dissolves in the water, lithium ions and fluorine ions are generated, as shown in reaction formula (2). At this time, the calcium ions and fluorine ions combine to generate calcium fluoride (CaF ₂ ), as shown in reaction formula (3). When the fluorine ion concentration in the aqueous solution decreases due to the generation of calcium fluoride, the ionization of lithium fluoride, i.e., its dissolution, is promoted. As a result of the promotion of the dissolution of lithium fluoride, the lithium ions in the aqueous solution increase.

The residue remaining after immersion in the first dissolving tank 21 may contain a small amount of lithium carbonate that was not dissolved in the first dissolving step P21. The lithium carbonate contained in the residue is dissolved in the second dissolving tank 25. However, even in this case, the amount of lithium carbonate introduced into the second dissolving tank 25 is less than the amount of lithium carbonate introduced into the first dissolving tank 21, and furthermore, the second dissolving tank 25 has a higher solid-liquid ratio than the first dissolving tank 21, so the lithium concentration is diluted, and therefore the effect on the dissolution of lithium fluoride in the second dissolving tank 25 is considered to be sufficiently small.

Lithium fluoride has a lower solubility than lithium carbonate. Therefore, the weight ratio of water to residue in the second dissolving tank 25 is set to be greater than the weight ratio of water to roasted material in the first dissolving tank 21. For example, the amount of water in the second dissolving tank 25 is set such that the weight ratio of water to the residue introduced into the second dissolving tank 25 is 20 times or more and 40 times or less.

If the weight ratio is less than 20, the lithium concentration will not be sufficiently dilute, and there is a risk that the lithium fluoride will not dissolve sufficiently. On the other hand, if the weight ratio exceeds 40, the second dissolution tank 25 will become too large and the amount of water consumed will increase, resulting in increased costs. In contrast, by setting the amount of water in the second dissolution tank 25 to a weight ratio of 20 to 40 times the weight of the residue introduced into the second dissolution tank 25, it is possible to sufficiently dissolve the lithium fluoride contained in the residue in the second dissolution tank and prevent increases in costs. Note that the weight ratio is more preferably 25 to 35 times. A weight ratio of approximately 28 times is even more preferable.

The second separation process P26 performs a second solid-liquid separation on the aqueous solution treated in the second dissolution process P25. For this purpose, the second separator 26 is composed of a solid-liquid separator. By performing solid-liquid separation using the second separator 26, solid residues containing calcium fluoride and other impurities are removed from the aqueous solution. The calcium separation process P27 separates excess calcium derived from calcium hydroxide and lithium from the aqueous solution separated in the second solid-liquid separation.

The calcium separation step P27 includes a precipitation step P28 and a third separation step P29. Correspondingly, the calcium separation device 27 includes a precipitation tank 28 and a third separator 29. In the precipitation step P28, carbon dioxide gas is bubbled into the aqueous solution separated in the second solid-liquid separation. For this purpose, the precipitation tank 28 is configured to be able to introduce carbon dioxide gas. By bubbling carbon dioxide gas into the aqueous solution in the precipitation tank 28, excess calcium derived from the calcium hydroxide introduced in the second dissolution step P25 is precipitated as solid calcium carbonate (CaCO ₃ ). Therefore, lithium and calcium contained in the aqueous solution separated in the second solid-liquid separation can be easily separated. This makes it possible to prevent the purity of the recovered lithium carbonate from being reduced by the added calcium.

In this embodiment, the bubbling with carbon dioxide gas is carried out so that the pH of the aqueous solution separated in the second solid-liquid separation is within the range of 8 to 10. If the pH of the aqueous solution after bubbling is less than 8, the precipitated calcium carbonate may re-dissolve as calcium bicarbonate (Ca(HCO ₃ ) ₂ ), making it impossible to separate calcium from lithium. Furthermore, since the pH of the aqueous solution before bubbling is around 12, if the pH of the aqueous solution after bubbling is greater than 10, excess calcium cannot be sufficiently precipitated. In contrast, by carrying out the bubbling with carbon dioxide gas so that the pH of the aqueous solution separated in the second solid-liquid separation is within the range of 8 to 10, calcium in the aqueous solution can be appropriately separated from lithium. The pH of the aqueous solution after bubbling is more preferably set to 8.5.

In the third separation process P29, a third solid-liquid separation is performed on the aqueous solution after bubbling. For this purpose, the third separator 29 is composed of a solid-liquid separator. By performing solid-liquid separation in the third separator 29, solid residues such as calcium carbonate are removed from the aqueous solution. The aqueous solution separated in the third solid-liquid separation is introduced into the lithium recovery device 24.

In this embodiment, the recovery process P2 includes a storage process P23 in which the aqueous solution separated in the first solid-liquid separation and the aqueous solution separated in the third solid-liquid separation are temporarily stored. For this reason, the recovery system 2 is equipped with a buffer tank 23 into which the aqueous solution discharged from the first separator 22 and the aqueous solution discharged from the third separator 29 are introduced. As a result, lithium in the aqueous solution separated in the third solid-liquid separation is also recovered in the lithium recovery process P24.

As described above, according to this embodiment, the roasted product obtained by roasting waste lithium-ion batteries is immersed in water in the first dissolving tank 21, and the resulting residue is then immersed in water again in the second dissolving tank 25, which is different from the first dissolving tank 21. At this time, calcium hydroxide is added to the second dissolving tank 25. This promotes the dissolution of lithium fluoride contained in the residue, allowing the lithium contained in the residue to be recovered. This therefore increases the lithium recovery rate.

Here, the reason why calcium hydroxide is not added to the first dissolving tank 21 will be explained. As mentioned above, roasted waste LIB is introduced into the first dissolving tank 21. This roasted material contains at least lithium carbonate and lithium fluoride as lithium compounds. The solubility of lithium carbonate in water is greater than the solubility of lithium fluoride in water. Therefore, in the first dissolving tank 21, dissolution of lithium carbonate predominates, and dissolution of lithium fluoride hardly occurs. Furthermore, the fact that the amount of lithium carbonate in the roasted material is greater than the amount of lithium fluoride is also cited as one of the reasons why lithium fluoride is difficult to dissolve.

Therefore, even if calcium hydroxide is added to the aqueous solution in the first dissolution tank 21, the dissolution of lithium carbonate will saturate the lithium ions, preventing the dissolution of lithium fluoride. Based on this knowledge, the inventors came up with the idea of immersing the residue containing lithium fluoride in new water, i.e., water that is not saturated with lithium ions, in a second dissolution tank 25 different from the first dissolution tank 21, in order to dissolve lithium fluoride in water.

Lithium fluoride that does not dissolve in the first dissolution tank 21 and is separated as residue is immersed in water again in the second dissolution tank 25, whereby the lithium fluoride dissolves and the lithium component contained in the lithium fluoride can be recovered.

Many modifications and other embodiments of the present disclosure will be apparent to those skilled in the art from the above description. Therefore, the above description should be construed as illustrative only, and is provided for the purpose of teaching those skilled in the art the best mode of carrying out the present disclosure. Details of the structure or function thereof may be substantially changed without departing from the spirit of the present disclosure.

Other Embodiments
For example, in the above embodiment, a processing system is exemplified in which one or more devices or equipment correspond to each process, but the processing system may also be configured to realize multiple processes using one device or equipment.

Furthermore, in the above embodiment, an example was given in which the aqueous solution separated in the calcium separation device 27 was mixed with the aqueous solution separated in the first separator 22 and introduced into the lithium recovery device 24, but these aqueous solutions may also be processed separately. For example, the calcium separation device 27 may have the same function as the lithium recovery device 24, i.e., the function of performing the concentration and solid-liquid separation processes, after the third separation process P29.

Summary of the Disclosure
[Item 1]
A method for treating used lithium-ion batteries according to one aspect of the present disclosure is a method for recovering lithium from used lithium-ion batteries containing fluorine, the method comprising the steps of: roasting the used lithium-ion batteries to obtain a roasted product, introducing the roasted product into a first dissolving tank and immersing it in water; performing a first solid-liquid separation on the aqueous solution obtained after immersion in the first dissolving tank; recovering the lithium from the aqueous solution separated by the first solid-liquid separation; introducing the residue obtained after immersion in the first dissolving tank into a second dissolving tank different from the first dissolving tank and immersing it in water; adding calcium hydroxide to the water in the second dissolving tank; performing a second solid-liquid separation on the aqueous solution obtained after immersion in the second dissolving tank; and separating excess calcium derived from the calcium hydroxide and the lithium from the aqueous solution separated by the second solid-liquid separation.

According to the above method, the roasted product obtained by roasting waste lithium-ion batteries is immersed in water in a first dissolving tank, and the resulting residue is then immersed in water again in a second dissolving tank that is different from the first dissolving tank. During this process, calcium hydroxide is added to the second dissolving tank. This promotes the dissolution of lithium fluoride contained in the residue, allowing the lithium contained in the residue to be recovered. This results in a high lithium recovery rate.

[Item 2]
In the method for treating waste lithium-ion batteries according to Item 1, the weight ratio of the amount of water in the second dissolving tank to the amount of the residue introduced into the second dissolving tank may be 20 to 40 times. This makes it possible to sufficiently dissolve lithium fluoride contained in the residue in the second dissolving tank and to suppress an increase in costs.

[Item 3]
In the method for treating waste lithium-ion batteries according to Item 1 or 2, the aqueous solution separated in the second solid-liquid separation may be bubbled with carbon dioxide gas, and the aqueous solution after the bubbling may be subjected to a third solid-liquid separation to remove the excess calcium as a solid. By performing the bubbling with carbon dioxide gas, the excess calcium derived from the calcium hydroxide added in the second dissolution tank can be precipitated. Therefore, lithium and calcium contained in the aqueous solution separated in the second solid-liquid separation can be easily separated. This makes it possible to prevent the purity of the recovered lithium carbonate from being reduced by the added calcium.

[Item 4]
In the method for treating waste lithium-ion batteries according to Item 3, the bubbling with carbon dioxide gas may be carried out so that the pH of the aqueous solution separated in the second solid-liquid separation falls within a range of 8 to 10. This allows calcium in the aqueous solution to be appropriately separated from lithium.

[Item 5]
A treatment system for waste lithium-ion batteries according to another aspect of the present disclosure is a treatment system for waste lithium-ion batteries for recovering lithium from waste lithium-ion batteries containing fluorine, the treatment system including: a first dissolving tank into which a roasted product obtained by roasting the waste lithium-ion batteries is introduced and immersed in water; a first separator that performs a first solid-liquid separation on the aqueous solution after immersion in the first dissolving tank; a lithium recovery device that recovers the lithium from the aqueous solution separated by the first separator; a second dissolving tank different from the first dissolving tank, into which a residue after immersion in the first dissolving tank is introduced and immersed in water to which calcium hydroxide is added; a second separator that performs a second solid-liquid separation on the aqueous solution after immersion in the second dissolving tank; and a calcium separation device that separates excess calcium derived from the calcium hydroxide and the lithium from the aqueous solution separated by the second solid-liquid separation, wherein calcium hydroxide is added to the water in the second dissolving tank.

2. Collection system (treatment system)
21 First dissolution tank 22 First separator 24 Lithium recovery device 25 Second dissolution tank 26 Second separator 27 Calcium separation device

Claims (5)

A method for treating waste lithium ion batteries to recover lithium from waste lithium ion batteries containing fluorine, comprising:
a roasted product obtained by roasting the waste lithium ion batteries is introduced into a first dissolving tank and immersed in water;
performing a first solid-liquid separation on the aqueous solution after immersion in the first dissolution tank;
recovering the lithium from the aqueous solution separated by the first solid-liquid separation;
The residue after immersion in the first dissolution tank is introduced into a second dissolution tank different from the first dissolution tank and immersed in water;
adding calcium hydroxide to the water in the second dissolution tank;
performing a second solid-liquid separation on the aqueous solution after immersion in the second dissolution tank;
the excess calcium derived from the calcium hydroxide and the lithium are separated from the aqueous solution separated by the second solid-liquid separation. The method for treating waste lithium-ion batteries described in claim 1, wherein the weight ratio of the amount of water in the second dissolution tank to the amount of the residue introduced into the second dissolution tank is 20 times or more and 40 times or less. bubbling carbon dioxide gas into the aqueous solution separated by the second solid-liquid separation;
3. The method for treating waste lithium ion batteries according to claim 1, further comprising the step of: subjecting the aqueous solution after the bubbling to a third solid-liquid separation; and removing the excess calcium as a solid. The method for treating waste lithium-ion batteries described in claim 3, wherein the bubbling with carbon dioxide gas is carried out so that the pH of the aqueous solution separated in the second solid-liquid separation is within the range of 8 to 10. A waste lithium ion battery treatment system for recovering lithium from waste lithium ion batteries containing fluorine, comprising:
a first dissolution tank into which a roasted product obtained by roasting the waste lithium ion batteries is introduced and immersed in water;
a first separator that performs a first solid-liquid separation on the aqueous solution after immersion in the first dissolution tank;
a lithium recovery device that recovers the lithium from the aqueous solution separated by the first separator;
a second dissolution tank different from the first dissolution tank, into which the residue obtained after immersion in the first dissolution tank is introduced and immersed in water to which calcium hydroxide is added;
a second separator that performs a second solid-liquid separation on the aqueous solution after immersion in the second dissolution tank;
a calcium separation device that separates excess calcium derived from the calcium hydroxide and the lithium from the aqueous solution separated by the second solid-liquid separation.