JP2020184487A - Recovering method for positive electrode material for lithium-ion battery - Google Patents

Abstract

To provide a collection method of controlling processing costs by using fuel such as heavy oil or electric power required for heating, and recovering highly valuable metals such as cobalt, nickel, and lithium from a lithium-ion secondary battery without being subject to legal restrictions on the installation and operation of industrial heating furnaces.SOLUTION: A recovering method of a positive electrode material from a lithium ion secondary battery includes a salt water discharge step S01 of immersing a lithium ion secondary battery containing cobalt, nickel and lithium as a positive electrode material in salt water to remove residual charges, a crushing step S02 of crushing the lithium-ion secondary battery whose residual charge has been removed in the salt water discharge step to a maximum size of 10 mm or less, a magnetic force sorting step S03 of sorting and removing an iron material from the crushed material crushed in the crushing step by magnetic force, and a sieve sorting step S04 of sieving the crushed material from which the iron material has been removed in the magnetic force sorting step to sort and collect the crushed material having a maximum size of 2.8 mm or less.SELECTED DRAWING: Figure 1

Description

The present invention relates to, for example, cobalt, nickel from a defective lithium ion secondary battery generated in the manufacturing process, or a positive electrode of a lithium ion secondary battery mounted on a notebook computer or a home appliance and discarded at the end of the battery life. , A method for recovering a positive electrode material containing a large amount of a valuable metal material such as lithium.

Lithium-ion secondary batteries are lighter and higher-capacity secondary batteries than lead-acid batteries, NiCad secondary batteries, nickel-metal hydride secondary batteries, etc., and are used in hybrid vehicles, electric vehicles, mobile phones, laptop computers, etc. Widely used. Due to the great demand for lithium-ion secondary batteries in recent years, the treatment of used lithium-ion secondary batteries, which are expected to be discarded in large quantities in the future, is becoming a problem. Further, lithium cobalt oxide, lithium nickel oxide, nickel-manganese-cobalt oxide and the like are used as the positive electrode material of the lithium ion secondary battery. These materials contain valuable metals such as cobalt, nickel, and lithium, and it is desired to recycle them together with inexpensive treatment.

Patent Document 1 describes a mechanical crusher and a vibrating sieve sorter after heating a lithium ion secondary battery to 500 degrees Celsius to 650 degrees Celsius using a furnace such as a rotary kiln furnace, a fluidized bed furnace, or a stalker furnace. A treatment method has been proposed in which the positive electrode material is recovered and reused.

Japanese Unexamined Patent Publication No. 2012-248323

However, in the technique of Patent Document 1, since the lithium ion secondary battery is heated by using a furnace, the processing cost is high. Therefore, it is presumed that the economic rationality is low in comparison with the value of the recovered valuable metal. In addition, when installing an industrial heating furnace, there are legal restrictions on the installation location and safety measures, so the number of companies that collect and process lithium-ion secondary batteries is limited. Therefore, it is presumed that insufficient processing capacity becomes a problem in order to process the used lithium ion secondary battery, which is expected to increase in the future.

The present invention solves the problem of the recovery method using a heating process, suppresses the processing cost due to the use of fuel such as heavy oil or electric power required for heating, and is a method relating to the installation and operation of an industrial heating furnace. It is an object of the present invention to provide a recovery method capable of recovering highly valuable metals such as cobalt, nickel and lithium from a lithium ion secondary battery without being subject to various restrictions.

The processing flow for achieving the above object is as follows. That is, one aspect of the recovery method of the present invention is a salt water discharge step of immersing a lithium ion secondary battery containing cobalt, nickel and lithium as a positive electrode material in salt water to remove residual charges, and a salt water discharge step of residual charges. A crushing step of crushing the lithium ion secondary battery from which the electric charge has been removed to a maximum size of 10 mm or less, a magnetic force sorting step of sorting and removing an iron material from the crushed material crushed in the crushing step by magnetic force, and a magnetic force sorting step. The crushed material from which the iron material has been removed is sieved, and the crushed material having a maximum size of 2.8 mm or less is sorted and collected.

According to the recovery method of the above aspect, it is possible to recover a positive electrode material containing a large amount of highly valuable metal materials such as nickel, cobalt and lithium from a lithium ion secondary battery while suppressing costs.

The processing flow diagram which shows the recovery method of one Embodiment of this invention. The figure of the uniaxial crusher used for the recovery method of FIG. FIG. 5 is a graph showing a comparison between the particle size distribution of the crushed product of the recovery method of FIG. 1 having no heating step and the particle size distribution of the crushed product of the recovery method of Patent Document 1 having a heating step. The graph which shows the relationship between the screen opening of the uniaxial crusher of FIG. 2 and the weight ratio of a crushed material. The figure which shows the composition analysis result of the crushed matter of the recovery method of FIG. 1 which does not have a heating step, and the composition analysis result of the crushed matter of the recovery method of Patent Document 1 which has a heating step. The figure which shows the relationship between the particle size range and the recovery rate of a valuable metal based on the composition analysis result of FIG. 5 about the recovery method of FIG. 1 and the recovery method of Patent Document 1.

The method for recovering the positive electrode material from the lithium ion secondary battery of the present invention will be described in detail with reference to FIG. FIG. 1 is a processing flow chart showing a method of recovering a positive electrode material from a lithium ion secondary battery according to an embodiment of the present invention.

As shown in FIG. 1, the method for recovering the positive electrode material from the lithium ion secondary battery according to the embodiment of the present invention includes at least a salt water discharge step S01, a crushing step S02, a magnetic force sorting step S03, and a sieve sorting step S04. This recovery method can further include other steps as needed.

The lithium ion secondary battery to be treated is not particularly limited. By the above recovery method, for example, a battery mounted on a home appliance or a notebook computer, which is generated in the manufacturing process of a used lithium ion secondary battery that has been discarded and recovered due to its life, or a lithium ion secondary battery. The positive electrode material can be recovered from the defective lithium ion secondary battery.

The shape of the lithium ion secondary battery is not particularly limited. According to the recovery method, the positive electrode material can be recovered from a lithium ion secondary battery having a shape such as a cylinder, a button, a coin, or a square.

Examples of the positive electrode material constituting the lithium ion secondary battery include lithium cobalt oxide, lithium cobalt nickel oxide, and the like.

In the salt water discharge step S01, the internal charge of the recovered lithium ion battery is removed. This prevents the occurrence of an internal short circuit that causes heating, ignition, etc. when the lithium ion secondary battery is crushed in the next crushing step S02. As a specific method, the recovered lithium ion secondary battery is put into a drum can or a resin container in which salt water is stored and immersed for a certain period of time to promote discharge. There is no particular limitation on the concentration of salt water. In this embodiment, as an example, a salt solution obtained by mixing about 1 kg of salt with 100 liters of tap water is used.

The immersion time is preferably selected as appropriate depending on the air temperature and the type of lithium ion battery, but it is possible to remove most of the residual charge by immersing the battery for 14 days or more.

In the crushing step S02, the lithium ion secondary battery from which the residual charge has been removed by the salt water discharge step S01 is crushed by a mechanical crusher. As the crusher used in the crushing step S02, a uniaxial crusher as shown in FIG. 2 is preferable. The lithium ion secondary battery 1 charged from the charging port 2 of the uniaxial crusher shown in FIG. 2 is crushed by the rotary blade 3 and the fixed blade 4. Specifically, the lithium ion secondary battery 1 is crushed so as to be scraped off little by little by being pressed against the rotary blade 3 by the pusher 5. That is, when the rotary blade 3 scratches the case made of the iron material containing the positive electrode material of the lithium ion secondary battery 1, the case is torn off, and in the subsequent sieve sorting step S04, the inside of the lithium ion secondary battery 1 It is possible to accurately separate the positive electrode material and the case. Further, a screen 6 is provided below the rotary blade 3 of the uniaxial crusher. The lithium ion secondary battery 1 is repeatedly crushed by the rotary blade 3 and the fixed blade 4 until the size of the screen 6 is equal to or smaller than the opening of the screen 6. The crushed material 7 that is below the opening of the screen 6 is discharged below the screen 6.

The recovery method is different from the recovery method of Patent Document 1 in that a heating step by an incinerator is not used. In the recovery method described in Patent Document 1, the lithium ion secondary battery is heated in the range of 500 degrees Celsius to 650 degrees Celsius. This is a binder component that binds the positive electrode material and the aluminum foil coated with the positive electrode material, for example, homopolymers or copolymers such as bilinidene fluoride, tetrafluoroethylene, acrylonitrile, ethylene oxide, and styrene. This is because the resin binder such as butadiene rubber is carbonized to weaken the binding force, thereby promoting the peeling of the positive electrode material from the aluminum foil in the crushing step and the sieve sorting step, and increasing the recovery rate of the positive electrode material.

FIG. 3 is a graph comparing the particle size distribution of the crushed product 7 of the method of one embodiment of the present invention having no heating step with the particle size distribution of the crushed product 7 of the method of Patent Document 1 having a heating step.

Using the above recovery method and the recovery method of Patent Document 1, a 50 kg lithium ion secondary battery in which the residual water was dried for 72 hours in the sun after being immersed in salt water for 2 weeks in the salt water discharge step S01 was crushed. An experiment was conducted. FIG. 3 shows the particle size distribution of the crushed product 7 obtained as a result of the experiment. In FIG. 3, comparing the weight ratio of the crushed material 7 having the maximum size of 0.25 mm or less, which is considered to contain a large amount of valuable metal, the recovery method of Patent Document 1 having a heating step is 43.2%. On the other hand, 51% of the recovery methods did not have a heating step. That is, when the crushed material 7 was crushed to the maximum size of 0.25 mm or less, the difference in the weight ratio of the crushed material 7 was small, and it was found that the presence or absence of the heating step did not significantly affect the recovery rate of the positive electrode material.

FIG. 4 is a graph showing the relationship between the opening of the screen 6 of the uniaxial crusher of FIG. 2 and the weight ratio of the crushed material 7. An experiment was conducted in which a 50 kg lithium ion secondary battery from which the internal charge had been removed in the salt water discharge step S01 was crushed using a uniaxial crusher. In this experiment, the opening dimensions of the screen 6 of the uniaxial crusher were changed to 6 mm in diameter, 10 mm in diameter, 15 mm in diameter, and 20 mm in diameter, and the opening of the screen 6 and the weight ratio of the crushed crushed material 7 were changed. I investigated the relationship. The lithium ion secondary battery used for crushing is a cylindrical lithium ion secondary battery having a diameter of 18 mm and a length of 65 mm. After being immersed in salt water for 2 weeks in the salt water discharge step S01, it was dried in the sun for 72 hours. The one obtained by drying the residual water was used.

As shown in FIG. 4, the larger the opening of the screen 6, the larger the weight ratio of the crushed material 7 having the largest size, and the smaller the opening of the screen 6, the smaller the crushed material 7 having the maximum size. This experiment showed that the weight ratio tended to increase. The small maximum size of the crushed material 7 means that the case that is the exterior of the lithium ion secondary battery and the positive electrode material contained therein are sufficiently separated.

Referring to FIG. 4, when the opening of the screen 6 is 6 mm in diameter and 10 mm in diameter, the weight ratio of the crushed material 7 of 0.25 mm or less is 50% or more. Therefore, it can be said that the opening of the screen 6 of the uniaxial crusher is preferably 6 mm or more in diameter and 10 mm or less in diameter.

When the crushing step S02 is performed using a uniaxial crusher having a screen 6 having an opening of more than 10 mm, the crushed product in which the case of the lithium ion secondary battery 1 and the positive electrode material are not sufficiently separated. 7 is discharged. Therefore, in the subsequent magnetic force sorting step S03, the case in which the positive electrode material is still attached to the surface is collected, and the recovery rate of the positive electrode material becomes extremely low. Further, when the opening of the screen 6 is smaller than 6 mm in diameter, it does not directly lead to a decrease in the recovery rate of the positive electrode material, but the processing time in the crushing step S02 becomes long.

In the magnetic force sorting step S03, the iron material is sorted and removed by magnetic force from the crushed material of the lithium ion secondary battery crushed in the crushing step S02. The apparatus used in the magnetic force sorting step is not particularly limited, and for example, a drum rotary magnetic force sorter or a suspended magnetic force sorter can be used.

The sieving sorting step S04 is a step of sieving a material other than the positive electrode material contained in the crushed product 7 of the lithium ion secondary battery after the iron material is removed by the magnetic force sorting step S03 to sort and remove the material. .. Examples of the material other than the positive electrode material include an aluminum foil coated with the positive electrode material, a copper foil coated with the negative electrode material, and an iron material left behind in the magnetic force sorting step S03. The apparatus used in the sieving sorting step is not particularly limited, and can be appropriately selected according to the purpose. For example, a vibrating sieve, a multi-stage vibrating sieve, a cyclone type sieve, or the like can be used in the sieve sorting step. The mesh size of the sieve of the apparatus used in the sieve sorting step is not particularly limited and may be appropriately selected depending on the intended purpose, but it is preferable to use a sieve having a mesh size of 0.5 mm to 2.8 mm.

FIG. 5 is a diagram showing the composition analysis result of the crushed product of the recovery method of FIG. 1 having no heating step and the composition analysis result of the crushed product of the recovery method of Patent Document 1 having a heating step. Composition analysis was performed on the crushed material shown in FIG. Specifically, (6) maximum size of 0.25 mm or less, (5) maximum size of more than 0.25 mm and 0.5 mm or less, (4) maximum size of more than 0.5 mm and 1.0 mm or less, Six types of particle size: (3) maximum dimensions exceeding 1.0 mm and 2.8 mm or less, (2) maximum dimensions exceeding 2.8 mm and 4.75 mm or less, and (1) maximum dimensions exceeding 4.75 mm. An appropriate amount of crushed material 7 is collected from each of the crushed material 7 selected in the range, and six types of metals, cobalt, nickel, lithium, iron, aluminum, and copper, contained in the positive electrode material by ICP emission spectroscopic analysis Content was measured. As a result, the highly valuable cobalt, nickel and lithium are crushed products having a maximum size of 0.25 mm or less in both the recovery method of Patent Document 1 having a heating step and the recovery method of FIG. 1 having no heating step. It was found that it was the most contained in. In both the recovery method of Patent Document 1 and the recovery method of FIG. 1, the recovered valuable metal is recycled into each single element by the solvent extraction treatment. The solvent extraction treatment is carried out by using an extractant suitable for each recovered element after undergoing a leaching step of dissolving the recovered metal powder in an acid solution of sulfuric acid or hydrochloric acid. In the leaching step, it is preferable that the maximum size is as small as possible because it takes time to dissolve the metal powder having a large maximum size and undissolved residue may be generated.

FIG. 6 is a diagram showing the relationship between the particle size range based on the composition analysis result of FIG. 5 and the recovery rate of valuable metals with respect to the recovery method of FIG. 1 and the recovery method of Patent Document 1. The recovery rate of the three highly valuable elements of cobalt, nickel and lithium is 94.9% for cobalt in the recovery method of Patent Document 1 having a heating step for the crushed product 7 having a maximum size of 2.8 mm or less. 93.5% of nickel and 95.5% of lithium can be recovered. On the other hand, in the recovery method of FIG. 1 which does not have a heating step, 93.1% of cobalt, 92.5% of nickel, and 92.3% of lithium can be recovered. Therefore, it can be said that the recovery method of FIG. 1 having no heating step can recover valuable metals equivalent to the recovery method of Patent Document 1 having a heating step.

That is, since the recovery method of one embodiment of the present invention does not have a heating step, a fuel such as heavy oil or electric power required for heating is used as compared with the recovery method of Patent Document 1 having a heating step. The processing cost can be suppressed, and there are no legal restrictions on the installation and operation of industrial heating furnaces. Further, the recovery method of one embodiment of the present invention can recover valuable metals at the same level as the recovery method of Patent Document 1 having a heating step.

The recovery method according to the embodiment of the present invention can recover valuable metals at a level equivalent to the treatment flow of Patent Document 1 having a heating step, but does not have a heating step. Since the load can be suppressed, it has great industrial applicability.

1 Lithium-ion secondary battery 2 Input port 3 Rotary blade 4 Fixed blade 5 Pusher 6 Screen 7 Crushed material

Claims (1)

A salt water discharge step in which a lithium ion secondary battery containing cobalt, nickel and lithium as a positive electrode material is immersed in salt water to remove residual charges, and
A crushing step of crushing the lithium ion secondary battery from which the residual charge has been removed in the salt water discharge step to a maximum size of 10 mm or less, and a crushing step.
A magnetic force sorting step of sorting and removing an iron material from the crushed material crushed in the crushing step by a magnetic force.
Recovery of positive electrode material from a lithium ion secondary battery having a sieving step of sieving the crushed material from which the iron material has been removed in the magnetic force sorting step to sort and recover the crushed material having a maximum size of 2.8 mm or less. Method.

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