JP2017084681A - Method for recovering positive electrode material of used lithium ion secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for recovering a positive electrode material of a lithium ion secondary battery, by which an active material, i.e. a positive electrode material of a used lithium ion secondary battery, and a current collector can be separated by a simple and convenient process, and the positive electrode material can be recovered inexpensively.SOLUTION: A method for recovering a positive electrode material from a used lithium ion secondary battery according to the present invention comprises the steps of: disassembling the used lithium ion secondary battery to obtain a member including the positive electrode material; performing a heat treatment on the member including the positive electrode material at a temperature of 500-600°C under an atmosphere of room air; and then immersing the object subjected to the heat treatment in water to process the same by ultrasonic waves for a given length of time.SELECTED DRAWING: None

Description

  The present invention relates to a method for recovering a positive electrode material of a used lithium ion secondary battery, and more specifically, from a used lithium ion secondary battery, an active material (metal compound) that is the positive electrode material, a current collector, It is related with the collection | recovery method of the positive electrode material of the used um ion secondary battery which can fractionate by simple process and can collect | recover positive electrode material at low cost.

  Lithium ion secondary batteries are widely used in mobile devices such as mobile phones, laptop computers, and automobiles, and their usage is growing rapidly.

  Various positive electrode active materials such as LCO (lithium cobaltate), LMO (lithium manganate), and NCA (lithium nickelate) are used as positive electrode materials for lithium ion secondary batteries. Has been studied. These lithium ion secondary batteries can be used repeatedly for charging and discharging. However, the capacity of the lithium ion secondary battery decreases as charging and discharging are repeated, so-called capacity deterioration occurs. Therefore, it is hoped that these positive electrode materials will be recovered from used lithium ion secondary batteries as they are, and the mechanism of capacity degradation will be elucidated by evaluating the particle size, shape, crystal structure, etc. of the active material. It is rare. However, in order to make such an evaluation, there is a problem that a recovery method suitable for taking out the positive electrode material from the used battery as it is is not known.

  So far, various methods have been studied for the recovery of positive electrode materials from lithium ion secondary batteries. These include dissolving metal components such as cobalt, nickel, and manganese, which are valuable metals, in a high purity state. Most of the recovery methods were intended to be recovered by extraction and used again as a raw material.

For example, a secondary battery waste battery containing an active material is roasted at a temperature of 600 ° C. or higher in an oxygen-containing gas stream, the baked product is cut, the cut product is sieved, and the baked product is selected with a magnet and acidified. A technique for recovering a positive electrode material of a valuable metal by dissolving and extracting a solvent from an acid solution with an organic solvent has been proposed (see Patent Document 1).

However, this method has a roasting step at a high temperature and an extraction step with an acid or an organic solvent, so that it can be recovered with a relatively high purity and a high yield, but the process is complicated and expensive. It is a collection method.

In addition, by adding carbon to lithium cobaltate and reducing and roasting in an inert gas atmosphere at a temperature of 700 ° C. or higher, a roasted product is obtained, and the roasted product is leached with water. There has been proposed a method of eluting and recovering lithium components in the pottery. (See Patent Document 2)

This method is roasting with lithium cobaltate alone, not intended for waste batteries of lithium secondary batteries, and recovering positive electrode materials in the waste batteries as they are by reduction roasting at high temperature. I can't expect that.

Further, as an improved method of this method, by adding carbon to lithium cobaltate and baking at a temperature of 500 ° C. or higher and 1000 ° C. or lower in an air atmosphere, an oxidizing atmosphere, and a reducing atmosphere, a roasted product And leaching the roasted product with water to elute and recover the lithium component in the roasted product. (See Patent Document 3)

Although this method can efficiently recover the lithium component from the waste battery, it cannot efficiently recover the positive electrode material, and the positive electrode material in the waste battery is recovered as it is by reducing and baking at high temperature. I can't expect to do it.

Japanese Patent Laid-Open No. 10-046266 JP 2004-11010 A JP 2011-94228 A

  As described above, there are various problems in the method for recovering the positive electrode material from various lithium ion secondary batteries, and a method for easily recovering the positive electrode material from the used lithium ion secondary battery as it is is desired. It was rare.

Accordingly, the present invention provides a used lithium ion secondary battery that can separate an active material and a current collector, which are positive electrode materials of a used lithium ion secondary battery, by a simple process and recover the positive electrode material at a low cost. An object of the present invention is to provide a method for recovering the positive electrode material.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have determined electrode materials for secondary batteries such as LCO (lithium cobaltate), LMO (lithium manganate), and NCA (lithium nickelate). It was found that the above-mentioned problems can be solved by efficiently recovering the positive electrode active material by a simple operation by roasting under the roasting conditions of the above, immersing the roasted product in water, and vibrating with ultrasonic waves. The present invention has been completed.

Specifically, the following items are provided.
The method for recovering the positive electrode material of the used lithium ion secondary battery of the present invention is characterized by including the following processing steps 1) to 3).
A step of disassembling a used lithium ion secondary battery to obtain a member containing a positive electrode material.
-The process of heat-processing the member containing positive electrode material at the temperature of 500 to 600 degreeC by air | atmosphere atmosphere.
-Thereafter, the step of immersing the heat-treated product in water and subjecting it to ultrasonic treatment for a predetermined time.

By performing the above steps 1) to 3), the positive electrode active material of the used lithium ion secondary battery can be recovered as it is.

  According to the method for recovering the positive electrode material of the used lithium ion secondary battery of the present invention, the binder component and the conductive assistant can be efficiently separated by heat treatment in the air atmosphere at a temperature of 500 ° C. to 600 ° C., It is an extremely simple treatment method that does not use any organic solvent as a solvent, and uses only water as a solvent and performs ultrasonic treatment as in the conventional recovery method, and is the original purpose. It is possible to provide a method for recovering a positive electrode material active material in which the positive electrode active material can be efficiently recovered as it is contained in a used battery, and its industrial significance is great.

The method for recovering the positive electrode material of the used lithium ion secondary battery of the present invention is characterized by including the following processing steps 1) to 3).
A step of disassembling a used lithium ion secondary battery to obtain a member containing a positive electrode material.
-The process of heat-processing the member containing positive electrode material at the temperature of 500 to 600 degreeC by air | atmosphere atmosphere.
-Thereafter, the step of immersing the heat-treated product in water and subjecting it to ultrasonic treatment for a predetermined time.

  The positive electrode material active material of the lithium ion secondary battery to which the method for recovering the positive electrode material of the used lithium ion secondary battery of the present invention is applied is LCO (lithium cobaltate), LMO (lithium manganate), NCA (lithium nickelate) ) Etc.

  Next, the method for recovering the positive electrode material of the used lithium ion secondary battery of the present invention will be described in detail for each step.

<1. Step of disassembling a used secondary battery to obtain a member containing a positive electrode material>
First, in order to obtain a member including a positive electrode material from a used lithium ion secondary battery, it is necessary to safely disassemble the battery body.

If this process can be decompose | disassembled safely, there will be no restriction | limiting in particular, A well-known method can be used. For example, the lithium ion secondary battery body is preferably completely discharged in advance. For this purpose, the battery body is preferably immersed in water and discharged. Since it is completely discharged, it can be safely disconnected. Specifically, a sodium chloride aqueous solution having a concentration of 20 to 30% by mass is prepared, and when a used battery body is immersed in this, it is discharged, taken out, and using a shear or the like, the battery body part is cut, Remove the aluminum and stainless steel body and electrode terminals. Therefore, the member containing the positive electrode material, the member containing the negative electrode material, and the separator portion are separated to obtain a member containing the positive electrode material.

<2. Step of heat-treating member including positive electrode material at a temperature of 500 ° C. to 600 ° C. in an air atmosphere>
Next, a member containing the recovered positive electrode material is put in a crucible or the like, and heat-treated at a temperature of 500 ° C. or higher and 600 ° C. or lower in an air atmosphere using a combustion apparatus such as a burner or an electric furnace.

The atmosphere at the time of the heat treatment is that the object of the present invention is a simple method for recovering the positive electrode active material, so an air atmosphere that does not require adjustment of the atmosphere is selected, but oxygen is added so as to burn efficiently. May be. However, it should be noted that if oxygen is added too much, stable combustion does not occur and it becomes difficult to control the temperature.

  The temperature range of the heat treatment is set to a temperature range of 500 ° C. to 600 ° C., which is a temperature range in which the heat treatment can be performed without oxidizing the collected current collector included in the member mainly including the positive electrode material. Further, the temperature is such that the conductive assistant such as acetylene black and carbon and the binder (binder) such as fluororesin and fluororubber can be decomposed and removed.

Specific heat treatment conditions can be appropriately adjusted depending on the structure of the current collector and the binder constituting the positive electrode material. When the heat treatment temperature exceeds 600 ° C., the aluminum foil used as the current collector for the positive electrode material is oxidized and embrittled, so that the positive electrode active material and the current collector are subjected to ultrasonic treatment in water in the subsequent steps. When separating the aluminum foil, the aluminum foil of the current collector collapses, and the fine powder of the aluminum foil may be mixed into the positive electrode material. In addition, even when heat treatment is performed at a temperature lower than 500 ° C., the conductive assistant and binder (binder) contained in the positive electrode material are not sufficiently decomposed and removed, making it difficult to separate and lowering the recovery rate of the positive electrode material. This is not preferable.

  The heat treatment apparatus is not particularly limited as long as the heat treatment can be performed by controlling the treatment in a temperature range of 500 ° C. to 600 ° C. in an air atmosphere, and can be appropriately selected according to the treatment amount. For example, if the electrode material is several centimeters square, it may be placed in a platinum crucible and burned with a burner. When a large amount of electrode material is processed, the entire electrode material can be combusted evenly in an electric furnace.

<3. Step of immersing heat-treated product in water and subjecting to ultrasonic treatment for a predetermined time>
Finally, the heat-treated product is immersed in water and subjected to ultrasonic treatment for a predetermined time. When the amount of treatment is small, first, pure water is put in a beaker, the burned roast is immersed in the pure water, and ultrasonic treatment is performed for 5 to 10 seconds using an ultrasonic generator with an ultrasonic frequency of about 50 KHz. By doing so, the active material of the positive electrode material is easily separated from the current collector. At this time, when stirring is performed, the separation is performed more efficiently. If the amount of treatment increases, the amount of water required for the treatment may be adjusted by increasing the amount of water according to the amount of treatment, as long as the roasted product is completely immersed, and there is no particular limitation. Although the ultrasonic treatment time is not particularly limited, it is not preferable to perform ultrasonic treatment more than necessary because the foil of the current collector collapses due to the ultrasonic treatment for a long time and fine powder may be mixed.

By performing the above treatment, the positive electrode material active material and the current collector are separated in water. The current collector remains as it is and is taken out to obtain a dispersion of the positive electrode material active material. This can be filtered and dried, and the positive electrode material active material can be recovered while remaining in the used lithium ion secondary battery body.

In the present invention, since the purpose is to recover the positive electrode active material, no particular explanation will be given, but naturally lithium can also be recovered from a solution from which lithium is eluted.

  EXAMPLES Hereinafter, although this invention is demonstrated further more concretely using an Example, this invention is not limited to these Examples.

[Example 1]
First, a commercially available lithium ion secondary battery was immersed in a 20% by mass aqueous sodium chloride solution and discharged until 0.05 V or less. After that, this lithium ion secondary battery body is cut, the internal electrode material is taken out, divided into a member containing a positive electrode material consisting of an active material and a current collector, a member containing a negative electrode material, and a separator, and cut into a 2 cm square as a sample. The member containing the positive electrode material was used.

  Next, the cut-out sample was put into a platinum crucible, and this platinum crucible was set on a burner. When the color of the platinum crucible became dark red (500 to 600 ° C.), the sample was lowered from the burner to obtain a roasted product.

  The obtained roasted product was put into a 100 ml beaker, pure water was put into a 100 ml beaker, and then put into an ultrasonic device having an ultrasonic frequency of 50 KHz, and subjected to ultrasonic vibration for 5 seconds. After the ultrasonic treatment, the beaker was taken out from the ultrasonic device, and the current collector (aluminum) from which the positive electrode active material was separated was taken out from the beaker using tweezers or the like. And in order to precipitate the positive electrode active material disperse | distributed in a pure water, it was left standing for a while, and after confirming precipitation of a positive electrode active material, the liquid from which lithium eluted from the inside of a beaker was separated and recovered.

  Furthermore, the beaker from which the liquid was recovered was placed in a drying apparatus heated to 100 ° C. and dried to obtain a positive electrode active material. The recovery rate of the positive electrode active material at this time was 94.3%. When the obtained positive electrode active material is observed with an electron microscope, no contamination of the current collector aluminum is observed, no alteration of the particles of the positive electrode active material is observed, and it can be determined that the positive electrode active material can be recovered as it is in the waste battery body. .

[Example 2]
In Example 2, the positive electrode active material was recovered in the same manner as in Example 1 except that a small electric furnace was used and the combustion treatment was performed for 30 minutes at 500 ° C. in the atmospheric atmosphere. The recovery rate of the positive electrode active material at this time was 95.6%. When the obtained positive electrode active material is observed with an electron microscope, no contamination of the current collector aluminum is observed, no alteration of the particles of the positive electrode active material is observed, and it can be determined that the positive electrode active material can be recovered as it is in the waste battery body. .

[Comparative Example 1]
In Comparative Example 1, the positive electrode active material was recovered in the same manner as in Example 1 except that it was heated to 800 ° C. with a burner. As a result, the positive electrode material became brittle, and the current collector collapsed and aluminum was mixed.

[Comparative Example 2]
In Comparative Example 2, the positive electrode active material was recovered in the same manner as in Example 2 except that the heating temperature of the electric furnace was 250 ° C. As a result, even when the separation treatment was performed, the positive electrode active material was hardly separated from the current collector and remained.

The active material recovery method of the present invention can grasp the state of the active material after being incorporated in the battery, observe the active material after the deterioration test and re-evaluate the particle size, and can be applied to elucidation of the deterioration mechanism. It can be used effectively for the development of lithium ion secondary batteries.

Claims (2)

A method of recovering positive electrode material from a used lithium ion secondary battery,
A method for recovering a positive electrode material from a used lithium ion secondary battery, comprising the following steps 1) to 3):
1) A step of decomposing a used lithium ion secondary battery to obtain a member containing a positive electrode material.
2) The process of heat-processing the member containing positive electrode material at the temperature of 500 to 600 degreeC by air | atmosphere atmosphere.
3) Thereafter, the step of immersing the heat-treated product in water and subjecting it to ultrasonic treatment for a predetermined time. 2. The used lithium ion secondary according to claim 1, wherein the positive electrode material is at least one positive electrode material selected from the group consisting of LCO (lithium cobaltate), LMO (lithium manganate), and NCA (lithium nickelate). A method for recovering positive electrode material from a battery.