JP2017037818A - Processing method of lithium ion battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a processing method for a lithium ion battery, capable of preventing the housing from bursting, during when the lithium ion battery is subjected to heating treatment.SOLUTION: In a method for heating and processing a lithium ion battery wrapped by a housing containing aluminum, by placing the lithium ion battery in a battery heating space, and sending hot gas thereto, temperature of the hot gas being sent to the battery heating space is set less than 450°C, the battery gas is made to flow out of the housing of the lithium ion battery, when the temperature of the lithium ion battery heated by the hot gas is 200°C to 400°C, and outflow of the battery gas is ended.SELECTED DRAWING: None

Description

  The present invention relates to a method of heating and treating a lithium ion battery whose periphery is covered with a casing containing aluminum, and in particular, rupture of the casing that encloses the periphery of the lithium ion battery during the heat treatment. The present invention proposes a technique that can prevent and contribute to the removal of aluminum from a lithium ion battery.

Lithium ion batteries used in various industrial fields including various electronic devices use a lithium metal salt containing manganese, nickel and cobalt as a positive electrode active material, and a positive electrode material and a negative electrode material containing the positive electrode active material In recent years, with the increase in the amount of use and the expansion of the range of use, the amount discarded due to defects in the product life of the battery and the manufacturing process has increased. Is in a situation.
Under such circumstances, it is desirable to easily recover valuable metals such as nickel and cobalt from lithium ion battery scrap that is discarded in large quantities at a relatively low cost for reuse.

To process lithium-ion batteries such as lithium-ion battery scraps for the recovery of valuable metals, first, the lithium-ion batteries are roasted to remove harmful electrolytes contained therein and render them harmless. At the same time, crushing and sieving are sequentially performed, and a pre-process for removing aluminum contained in the casing and the positive electrode substrate to some extent is performed.
Next, a leaching step of obtaining a post-leaching solution by acid leaching the powdered positive electrode active material obtained in the previous step and dissolving lithium, nickel, cobalt, manganese, aluminum, etc. that may be contained in the solution. Do.

  And after that, the collection | recovery process which isolate | separates each metal element melt | dissolved in the liquid after leaching is performed. Here, in order to separate each metal leached in the liquid after leaching, the liquid after leaching is sequentially subjected to multiple stages of solvent extraction or neutralization, etc. according to the metal to be separated. Back extraction, electrolysis, carbonation, and other treatments are performed on each solution obtained in (1). Specifically, each valuable metal can be recovered by first recovering aluminum, subsequently recovering manganese, then cobalt, then nickel, and finally leaving lithium in the aqueous phase.

By the way, as described above, when the lithium ion battery is heated and roasted before the lithium ion battery is acid leached, the casing constituting the exterior of the lithium ion battery may burst. It was. In this way, when the casing of battery scrap is ruptured by roasting, the aluminum contained in the casing and the positive electrode base material is oxidized and embrittled, and is easily crushed during crushing. Therefore, when the positive electrode active material is leached with acid, a large amount of aluminum is contained in the liquid after leaching.
As a result, man-hours for separation and removal of aluminum are required in the recovery process, which increases the cost.

  An object of the present invention is to solve such a problem, and the object of the present invention is to provide a lithium ion capable of effectively preventing the rupture of the casing during the heat treatment of the lithium ion battery. It is in providing the processing method of a battery.

As a result of intensive studies, the inventor has rapidly increased the temperature of the lithium ion battery to a high temperature of 450 ° C. or higher in the temperature rising process of increasing the temperature of the lithium ion battery higher than 400 ° C. The above-mentioned rupture of the casing is caused by the rapid rise in temperature of the lithium ion battery during heating, and the internal electrolyte rapidly vaporizes to generate a large amount of battery gas in the casing. It was thought that the cause was that the casing expanded when the gas generation flow rate exceeded the outflow rate to the outside of the casing. However, the present invention is not limited to such a theory.
Therefore, when using heating equipment that heats the object to be heated with hot gas, the temperature of the lithium ion battery is controlled by adjusting the hot gas temperature appropriately during the process of heating the lithium ion battery. Therefore, it was considered that the battery can be effectively roasted without rupturing the casing by slowly flowing out almost all the battery gas in the casing while the lithium ion battery is at a relatively low temperature.

  Under such knowledge, the method for treating a lithium ion battery according to the present invention is such that a lithium ion battery wrapped in a casing containing aluminum is disposed in a battery heating space, and hot gas is sent into the battery heating space. A method of heating and processing the lithium ion battery, wherein the temperature of the hot gas sent into the battery heating space is less than 450 ° C., and the temperature of the lithium ion battery heated by the hot gas is 200 ° C. to 400 ° C. While within the range, the battery gas is allowed to flow out of the casing of the lithium ion battery, and the flow of the battery gas is terminated.

  And it is preferable to raise the temperature of the hot gas sent into the said battery heating space to 450 to 600 degreeC after completion | finish of outflow of the battery gas from the inside of the said housing of a lithium ion battery.

  In the method for treating a lithium ion battery according to the present invention, the hot gas after being sent into the battery heating space from the start to the end of the outflow of the battery gas from within the casing of the lithium ion battery, together with the battery gas, It is preferable that the battery is discharged to the outside of the battery heating space to be 450 ° C. or higher.

  After the heating of the lithium ion battery as described above, it is preferable that the property wrapped in the casing of the lithium ion battery is maintained.

  In the method for treating a lithium ion battery according to the present invention, it is preferable that the battery heating space into which the hot gas is sent is a reducing atmosphere.

  According to the processing method of the lithium ion battery of the present invention, the temperature of the hot gas fed into the battery heating space is set to less than 450 ° C., so that the temperature of the lithium ion battery is in the range of 200 ° C. to 400 ° C. By causing the battery gas to flow out from the inside of the lithium ion battery casing and terminating the outflow of the battery gas, the generation of gas in the casing can be slowed down, thereby bringing about the rapid gas generation. It can effectively prevent body rupture.

It is the schematic of the heating apparatus which can be used for the processing method of the lithium ion battery which concerns on one Embodiment of this invention. 4 is a graph showing a change with time of a sample temperature in a heating process of Test Example 1. 6 is a graph showing a change with time of a sample temperature in a heating process of Test Example 2.

Hereinafter, embodiments of the present invention will be described in detail.
In the method for treating a lithium ion battery according to one embodiment of the present invention, as illustrated in FIG. 1, a lithium ion battery wrapped in a casing containing aluminum is disposed in a battery heating space, and the battery heating space In this method, the lithium ion battery is heated and processed by feeding the hot gas generated in the hot gas generator. In particular, here, while the temperature of the lithium ion battery heated by the hot gas is in the range of 200 ° C. to 400 ° C., the battery gas flows out of the casing of the lithium ion battery, and during that time, the battery gas flows out. Therefore, it is important that the temperature of the hot gas fed into the battery heating space is less than 450 ° C.

(Lithium ion battery)
The lithium ion battery that is the subject of the present invention may be any lithium ion battery that is used in mobile phones and other various electronic devices, but includes aluminum as a casing that surrounds the lithium ion battery. It shall have a housing. Among these, it is preferable from the viewpoint of effective utilization of resources to target so-called lithium ion battery scrap that is discarded due to the life of the battery product, manufacturing defects, or other reasons.

As a case of a lithium ion battery, for example, there are those made of only aluminum, and those containing aluminum, iron, aluminum laminate, and the like.
Note that a lithium ion battery includes a positive electrode active material made of one or more single metal oxides of lithium and nickel, cobalt, or manganese, or a composite metal oxide of two or more, It may include an aluminum foil (positive electrode base material) to which a substance is applied and fixed with an organic binder or the like. In addition, the lithium ion battery may contain copper, iron, or the like.
Further, in general, a lithium ion battery includes an electrolytic solution in a casing. For example, ethylene carbonate, diethyl carbonate, or the like may be used as the electrolytic solution.

  The lithium ion battery encapsulated in the housing can have a substantially square or rectangular planar outline shape. In this case, as dimensions before processing, for example, the length is 40 mm to 80 mm, and the width is Although 35 mm-65 mm and a thickness of 4 mm-5 mm can be made into a target, it is not limited to the thing of such a dimension shape.

(Heating process)
This heating process raises the temperature of the lithium ion battery to a temperature exceeding 400 ° C., removes the internal electrolyte, renders it harmless, and decomposes the binder that binds the aluminum foil and the positive electrode active material. The separation of the aluminum foil and the positive electrode active material during crushing and sieving is promoted to increase the recovery rate of the positive electrode active material recovered under the sieve, and the valuable metal contained in the lithium ion battery is It is performed for the purpose of changing to a form that can be easily leached in the leaching process.

A lithium ion battery having a casing as described above bursts when the temperature is rapidly increased in, for example, an incinerator. As a result, the casing is oxidized and becomes brittle, so that when the heated lithium ion battery is crushed, a large amount of aluminum constituting the casing and the like is contained in a fine powder form. Since such aluminum cannot be removed even by sieving and is mixed into the lithium ion battery powder added to the acidic solution in the leaching step, the work and cost of recovering it later increase.
Such a rupture during heating of the lithium ion battery is caused by a rapid rise in the temperature of the lithium ion battery from the start of heating, whereby the electrolyte in the casing is rapidly vaporized into battery gas. It is considered that the battery gas in the casing that is generated in a larger amount than the amount of battery gas that can flow out from the body expands and bursts the casing.

  In order to cope with this, in the embodiment of the present invention, a lithium ion battery encased in a casing containing aluminum is arranged in a battery heating space, and hot gas of less than 450 ° C. is first fed into the battery heating space. Thereby, the temperature of the lithium ion battery is raised, and when the temperature reaches the range of 200 ° C. to 400 ° C., the battery gas starts to flow out from the inside of the casing, and is within the temperature range of 200 ° C. to 400 ° C. In the meantime, the outflow of the battery gas is terminated. That is, by setting the hot gas temperature to less than 450 ° C., the temperature of the lithium ion battery before the end of the outflow of the battery gas from the housing can be maintained within a temperature range of 200 ° C. to 400 ° C.

  As a result, the generation of battery gas due to the evaporation of the electrolyte is performed slowly until the outflow of the battery gas from the casing is completed, so that the battery gas is prevented from being generated rapidly enough to expand the casing. It is possible to effectively prevent rupture of the housing and embrittlement due to oxidation. In addition, if the temperature in the battery heating space is raised too much during such a temperature rise process, the battery gas that has flowed out of the housing will ignite, causing a rapid rise in the temperature of the lithium ion battery and controlling the temperature of the lithium ion battery. It becomes difficult. Therefore, by setting the hot gas temperature to less than 450 ° C., the temperature in the battery heating space can be kept below 450 ° C., and such ignition of the battery gas is not caused.

  On the other hand, when the temperature of the hot gas before the end of the outflow of the battery gas is lower than 300 ° C., the outflow of the battery gas may not be performed sufficiently by not vaporizing the battery gas effectively. Therefore, it is preferable that the temperature of the hot gas before the end of the battery gas outflow is 300 ° C. or higher and lower than 450 ° C. The temperature of the hot gas before the end of the battery gas outflow is more preferably 350 ° C. or more and less than 450 ° C., and further preferably 400 ° C. or more and less than 450 ° C. The ambient temperature of the lithium ion battery in the battery heating space may be in the above range.

  Here, as to whether or not the outflow of the battery gas from the inside of the housing is completed, the mist-like material that has flowed out of the inside of the housing is visually confirmed, or the combustible component in the outflowed battery gas is analyzed. This can be confirmed by

The temperature range of the temperature raising process is set to 200 ° C. to 400 ° C. in order to keep the flow rate of the battery gas generated by the evaporation of the electrolyte below a predetermined amount. Thereby, until the end of the heating process, the state in which the original shape of the lithium ion battery is kept, that is, the property in which the lithium ion battery is wrapped in the casing is maintained, and then the casing or the like is obtained by subsequent decomposition or crushing, and sieving. The contained aluminum can be sufficiently removed.
In other words, if the temperature of the lithium ion battery is lower than 200 ° C. during the temperature rising process, the battery gas does not flow out from the casing, and the effect of the present invention cannot be obtained. If the temperature exceeds 400 ° C. before the end of gas outflow, the casing may burst due to an increase in the flow rate of battery gas. From such a viewpoint, in the temperature rising process, it is preferable to end the outflow of the battery gas within a temperature range of 200 ° C. to 400 ° C. In particular, the outflow of the battery gas is ended within a temperature range of 220 ° C. to 380 ° C. More preferably. This temperature can be measured by measuring the surface temperature of the casing of the lithium ion battery.

Here, the time for the temperature raising process to be in the range of 200 ° C. to 400 ° C. varies depending on the type, size, and other conditions of the lithium ion battery, but the temperature of the lithium ion battery is in the range of 200 ° C. to 400 ° C. It can be set as the time from the time of reaching 10 minutes or more, more preferably 20 minutes or more. That is, the average temperature rising rate of the lithium ion battery within the range of 200 ° C. to 400 ° C. is preferably 20 ° C./min or less, and more preferably 10 ° C./min or less. That is, when the average rate of temperature increase of the lithium ion battery in the range of 200 ° C. to 400 ° C. is higher than 20 ° C./min, the battery gas outflow from the inside of the casing may not be sufficiently completed in some cases. This is because the temperature may exceed 400 ° C., and there is a concern that the housing may burst.
On the other hand, the longer the time in the range of 200 ° C. to 400 ° C. is, the more reliably the end of battery gas outflow can be completed. The processing efficiency decreases due to the increase in processing time. Thereby, it can be normally made into 60 minutes or less, and also can be made into 30 minutes or less.

  In the temperature raising process, if the temperature of the lithium ion battery does not exceed 400 ° C. until the battery gas outflow from the housing is completed, the battery gas effectively flows out while preventing explosion due to rapid battery gas outflow. Can be made. Here, the battery gas is generally raised gently in the range of 200 ° C. to 400 ° C. until the outflow of the battery gas is completed. However, if possible, the temperature of the temperature raising process may be maintained at a specific temperature of one or more steps within the range of 200 ° C. to 400 ° C. until the outflow of the battery gas is completed.

Here, if the battery gas that has flowed out of the casing is present in the battery heating space from the start to the end of the flow of the battery gas out of the casing of the lithium ion battery, for example, the temperature of the hot gas is subsequently changed to 450 ° C. When the temperature is raised beyond the range, the battery gas may be ignited and the temperature in the battery heating space, and thus the temperature of the lithium ion battery, may not be controlled.
In order to prevent this, from the start of the outflow of the battery gas to the end of the outflow, as illustrated in FIG. 1, the hot gas after being sent into the battery heating space, together with the battery gas flowing out from the casing, is Exhaust to a gas ignition location outside the heating space, for example, away from the lithium ion battery placed in the battery heating space, and set the hot gas containing the battery gas to 450 ° C. or more outside thereof to ignite the battery gas. It is preferable to cause The ignition location may be a location away from the battery heating space to such an extent that the ignition does not affect the lithium ion battery.

After the outflow of the battery gas as described above, the temperature of the hot gas is raised to 450 ° C. to 600 ° C., so that the metal such as cobalt contained in the lithium ion battery can be easily acid leached, for example, oxidation It is changed to a form such as cobalt (CoO) or simple substance cobalt.
Here, almost all of the battery gas in the casing of the lithium-ion battery has already flowed out of the casing, so even if the hot gas temperature is high as described above, the casing ruptures and the aluminum contained therein There is no embrittlement due to oxidation.

  When the hot gas temperature after the end of the battery gas outflow is less than 450 ° C., for example, there is a concern that cobalt in the lithium ion battery does not sufficiently change to a form such as cobalt oxide or simple substance cobalt. When the hot gas temperature exceeds 600 ° C., there is a possibility that aluminum cannot be completely removed in the subsequent sieving step due to the inclusion of the positive electrode active material due to dissolution of aluminum having a melting point of 660 ° C. From such a viewpoint, the hot gas temperature after the end of the battery gas outflow is 450 ° C. to 600 ° C., and more preferably 450 ° C. to 550 ° C.

  After the outflow of the battery gas, the time for maintaining the hot gas temperature at 450 ° C. to 600 ° C. can be, for example, 20 minutes to 120 minutes. If the time for maintaining the hot gas temperature at 450 ° C. to 600 ° C. is too short, the shape change of the valuable metal in the lithium ion battery may be insufficient and may not be effectively leached in the subsequent leaching step. On the other hand, if this time is too long, there is no particular problem, but the processing efficiency decreases.

Although the heating step described above can be performed in an air atmosphere, the lithium ion battery may be heated with the battery heating space into which the hot gas is sent as a more inert atmosphere. Thereby, even if the aluminum casing is ruptured, the oxidation and embrittlement of aluminum and copper can be suppressed. Specifically, the battery heating space is, for example, in an atmosphere filled with argon, nitrogen, CO ₂ or other inert gas, or in an atmosphere more inert to the atmosphere by mixing these gases, The lithium ion battery can be heated.

  The heating equipment used in the heating process can heat the lithium ion battery by sending hot gas into the battery heating space where the lithium ion battery is arranged. As an example, the heating equipment shown in FIG. 1 includes a hot gas generating unit that generates hot gas by a burner or the like, a battery heating space in which a lithium ion battery is disposed, and hot gas is sent from the hot gas generating unit, and a battery. There is provided a gas flashing place that is sent after the hot gas and the battery gas sent into the heating space are discharged from the battery heating space.

Such a heating facility using a hot gas has an advantage that the temperature of the lithium ion battery can be easily controlled because the lithium ion battery can be easily heated to a predetermined temperature. In particular, in the present invention, it is important to control the temperature of the lithium ion battery in order to prevent rupture of the casing of the lithium ion battery. Therefore, it is effective to use a heating facility using such a hot gas.
Specifically, examples of the heating equipment include a rotary kiln furnace, a tunnel furnace, and a fixed bed furnace.

(Leaching process and recovery process)
By crushing and sieving as necessary after the above heating step, a sieving product containing a positive electrode active material in a granular or powder form from which aluminum has been sufficiently removed can be obtained.
Thereafter, nickel, cobalt, manganese dissolved in the leached solution from the leached solution obtained by leaching the sieved material containing the granular or powdered positive electrode active material added to an acidic solution such as sulfuric acid. Collect etc. Specifically, for example, manganese is first separated and recovered by solvent extraction or neutralization, then cobalt is separated and then nickel is sequentially separated, and finally lithium is left in the aqueous phase.

  Here, the heating step described above makes the metal dissolved in the solution after leaching almost free of aluminum, so that the processing required for separating and removing aluminum in the recovery step can be simplified or omitted. Thereby, improvement of processing efficiency and reduction of processing cost can be realized.

  Next, the treatment method of the present invention was experimentally carried out and the effects thereof were confirmed, and will be described below. However, the description here is for illustrative purposes only and is not intended to be limiting.

  In order to confirm whether or not bursting of the casing can be prevented by terminating the outflow of the battery gas from the casing while the temperature of the lithium ion battery is in the range of 200 ° C. to 400 ° C. Test Examples 1 and 2 were conducted.

(Test Example 1)
In an air atmosphere, a lithium ion battery with an Al casing was heated in a crucible furnace. Heating up to 550 ° C. after adjusting so that the temperature range of 200 ° C. to 400 ° C. is maintained for 10 minutes or more as shown in the graph of the sample temperature history in FIG. did. In the lithium ion battery after heating, although the expansion of the Al case was observed, the original form was maintained without the case being ruptured. The lithium ion battery after the heat treatment was crushed with a crusher, sieved and sieved with a sieve having an opening of 1 mm, and the positive electrode active material and the like were collected under the sieve. The grade of the sieved product (<1 mm) was Co 37%, Al 4.5%, Cu 0.7%, and the cobalt recovery rate was 98%. Table 1 shows the analysis value and recovery rate of the sieved product.

  The recovery rate referred to here is the weight of each sieved product recovered by crushing and sieving the heat-treated lithium ion battery, and the sample obtained by reducing each sieved product was dissolved in an acid and analyzed by an ICP emission spectrometer. From the quality of each sieve obtained from the analytical value, the amount of metal for each component was calculated and obtained as a percentage by weight of each metal in the sieve (<1 mm) with respect to the total amount of all metals in this product. is there.

  In Test Example 1, when the temperature of the lithium ion battery was set to a range of 200 ° C. to 400 ° C. over a relatively long time, the battery gas could be sufficiently discharged from the inside of the casing, and the lithium ion battery Rupture could be prevented. As a result, it can be seen from the results shown in Table 1 that the amount of aluminum in the sieved material could be reduced while recovering cobalt at a high recovery rate.

(Test Example 2)
In an air atmosphere, a lithium ion battery with an Al casing was heated in a crucible furnace. As shown in the graph of the sample temperature history in FIG. 3, the sample was heated at the full power of the heating capability of the electric furnace and then further heated to 550 ° C. At this time, the time for passing through the range of 200 ° C. to 400 ° C. was a rapid temperature rise that was less than 10 minutes. The lithium ion battery after heating was in a state where it was totally damaged, and a part of the inner aluminum foil was visible. The lithium ion battery after the heat treatment was crushed with a crusher, sieved and sieved with a sieve having an opening of 1 mm, and the positive electrode active material and the like were collected under the sieve. The quality of the sieved product (<1 mm) was 31% for Co, 7.0% for Al, 1.3% for Cu, and 71% for cobalt recovery. Table 2 shows the analysis value and recovery rate of the sieved product.

  In Test Example 2, it is considered that the lithium ion battery was damaged and most of the aluminum foil in the casing was oxidized due to the rapid increase in temperature during the temperature rising process of the lithium ion battery. From the results shown in Fig. 4, it can be seen that the amount of aluminum in the sieved product has increased.

From the results of Test Examples 1 and 2, generation of battery gas generated in the casing is completed by terminating the outflow of the battery gas from the casing while the temperature of the lithium ion battery is in the range of 200 ° C to 400 ° C. It was found that the housing could be prevented from rupturing due to the amount exceeding the outflow amount.
And if the temperature of the hot gas sent into the battery heating space around the lithium ion battery is less than 450 ° C., the time during which the temperature of the lithium ion battery is in the range of 200 ° C. to 400 ° C. is increased. According to the present invention, the casing of the lithium ion battery at the time of roasting can be easily set to 10 minutes or more, and the battery gas flowing out from the casing of the lithium ion battery does not ignite. It can be seen that the bursting of can be effectively prevented.

Claims (5)

A method of heating and treating the lithium ion battery by placing a lithium ion battery wrapped in a casing containing aluminum in the battery heating space and sending hot gas into the battery heating space,
While the temperature of the hot gas sent into the battery heating space is less than 450 ° C., and the temperature of the lithium ion battery heated by the hot gas is in the range of 200 ° C. to 400 ° C., the battery gas from the inside of the lithium ion battery housing And a process for treating the lithium ion battery, in which the outflow of the battery gas is terminated.   The processing method of the lithium ion battery of Claim 1 which raises the temperature of the hot gas sent into the said battery heating space to 450 to 600 degreeC after completion | finish of outflow of the battery gas from the inside of the housing | casing of the said lithium ion battery.   During the period from the start to the end of the outflow of the battery gas from the inside of the lithium ion battery casing, the hot gas sent into the battery heating space is discharged to the outside of the battery heating space together with the battery gas. The processing method of the lithium ion battery of Claim 1 or 2 made into 450 degreeC or more by this.   The processing method of the lithium ion battery as described in any one of Claims 1-3 with which the property enclosed by the said housing | casing of a lithium ion battery is maintained after completion | finish of the heating of the said lithium ion battery.   The processing method of the lithium ion battery as described in any one of Claims 1-4 which makes the battery heating space which sends in the said hot gas into a reducing atmosphere.