KR101359866B1 - Separating and recovering method of current collector and positive electrode active material from positive electrode material for lithium ion battery - Google Patents

Abstract

An object of the present invention is to provide a method capable of attaining high separation recovery efficiency of a positive electrode active material and a current collector at low cost.
(A) preparing a positive electrode material for lithium ion batteries having a structure in which a current collector and a positive electrode active material are bonded to each other by a binder, (B) cutting the positive electrode material for lithium ion batteries, and (C) a positive electrode after cutting The ash is sifted into a sieve having a scale of 100 to 200 mm to recover the positive electrode material under the sieve, and (D) imparting impact force to the positive electrode material under the sieve obtained by the step (C) to give the positive electrode from the current collector. Lithium including the process of peeling an active material, and (E) after process (D), sifting a positive electrode material into the sieve whose scale is 0.1-1.0 mm, and collect | recovering an electrical power collector in a collector upper part, and a lower body sieve. A method for separating and collecting a current collector and a positive electrode active material from a positive electrode material for an ion battery.

Description

Separation and recovery of current collector and positive electrode active material from positive electrode material for lithium ion battery {SEPARATING AND RECOVERING METHOD OF CURRENT COLLECTOR AND POSITIVE ELECTRODE ACTIVE MATERIAL FROM POSITIVE ELECTRODE MATERIAL FOR LITHIUM ION BATTERY}

The present invention relates to a method for separating and collecting a current collector and a positive electrode active material from a positive electrode material for a lithium ion battery.

Lithium ion batteries have a high energy density and a relatively high voltage, and are widely used for small electronic devices such as laptops, video cameras, digital cameras, and cellular phones. In the future, it is also promising to be used as a power source for large devices such as electric vehicles and distributed home type power supplies in general households.

The electrode body of a lithium ion battery generally has a stack structure in which the positive electrode, the separator, and the negative electrode are rolled up or stacked several times. Among these, the positive electrode is typically composed of a positive electrode current collector made of aluminum foil and a positive electrode active material made of a lithium composite oxide such as LiCoO ₂ , LiNiO _2, and LiMn ₂ O ₄ adhered to a surface of a positive electrode through a binder.

From the viewpoint of recycling, it is preferable that various metals can be separated and recovered from the positive electrode material included in the used lithium ion battery or the unnecessary positive electrode material generated in the manufacturing process of the lithium ion battery, but the positive electrode active material is firmly adhered to the current collector. Therefore, there was a need for a technique capable of easily separating and recovering this.

As one of the techniques for separating the current collector and the positive electrode active material, Japanese Patent Application Laid-open No. Hei 10-255862 (Patent Document 1), in which a method for wet treating a positive electrode material is known, discloses an electrode of a lithium ion secondary battery. The method of immersing in any one of the hydroxide solution of an alkali metal, the alcohol solution of an alkali metal, or an organic solvent, and separating the said electrode with an electrode material and an electrical power collector is described. In Japanese Patent Application Laid-Open No. 2005-327482 (Patent Document 2), a positive electrode plate made of a positive electrode substrate and a positive electrode active material is cut and immersed in an aqueous sulfuric acid solution having a pH of 0 to 3, so that the positive electrode substrate and the positive electrode active material remain solid. A method of separating and recovering is described.

Moreover, the method of carrying out a combustion process of a positive electrode material is known. In Japanese Patent Application Laid-Open No. Hei 10-8150 (Patent Document 3), after cutting the metal foil arrival waste material to a suitable size, for example, a size of several mm to several tens of mm by shredder or the like, A method of selectively decomposing and removing conductive agents such as acetylene black and carbon and binders such as fluorine resin and fluorine rubber, which are blended in the electrode material of the metal foil arrival waste material by combustion treatment in an oxygen-containing gas stream at 300 to 600 ° C. Is disclosed.

Japanese Patent Application Laid-open No. Hei 10-255862 Japanese Patent Application Publication No. 2005-327482 Japanese Patent Application Laid-open No. Hei 10-8150

As described above, a technique for separating the current collector and the positive electrode active material is known. However, in a wet treatment using an acid, there are disadvantages such as dissolution and mixing of loss, Al, which is a loss due to elution of Co and Ni, which are recovered products, and impurities. In the separation method using an organic solvent, although the recovery rate is high, there is a drawback that the treatment cost is high in addition to the removal of the solvent from the recovered positive electrode material and the safety of handling the solvent. In the method of a combustion process, a positive electrode material is collect | recovered by incineration of the organic material which is a binder (binder). However, problems such as poor recovery rate due to poor peeling of the positive electrode material, curling due to melting of Al, etc., and also different treatment conditions depending on the state of the scrap remain.

Therefore, an object of this invention is to provide the method different from the prior art which can achieve high separation recovery efficiency of a positive electrode active material and an electrical power collector at low cost.

MEANS TO SOLVE THE PROBLEM As a result of earnestly examining in order to solve the said subject, it discovered that the said subject can be solved by performing cutting, screening, and grinding in this order on predetermined conditions.

The present invention completed on the basis of the above knowledge in one aspect,

(A) process of preparing the positive electrode material for lithium ion batteries which has a structure by which an electrical power collector and a positive electrode active material adhere | attach with a binder,

(B) cutting the positive electrode material for lithium ion battery;

(C) sifting the positive electrode material after cutting by a sieve having a scale of 100 to 200 mm, and recovering the positive electrode material under the sieve;

(D) a step of peeling the positive electrode active material from the current collector by applying an impact force to the positive electrode material under the sieve obtained in step (C),

(E) After the step (D), the positive electrode material is screened by a sieve having a scale of 0.1 to 1.0 mm, and the current collector is collected from the positive electrode material for lithium ion batteries, including the step of recovering the current collector on the upper side and the positive electrode active material on the lower side of the sieve. And a method for separating and recovering the positive electrode active material.

In one embodiment of the method for separating and collecting the current collector and the positive electrode active material from the lithium ion battery positive electrode material according to the present invention, the positive electrode material obtained in the step (D) has a plurality of irregularities per 1 mm 2 of the observation field.

In another embodiment of the method for separating and collecting the current collector and the positive electrode active material from the lithium ion battery positive electrode material according to the present invention, step (D) is performed by an impact mill.

In another embodiment of the method for separating and collecting the current collector and the positive electrode active material from the lithium ion battery positive electrode material according to the present invention, the impact mill is a hammer mill.

In another embodiment of the method for separating and collecting the current collector and the positive electrode active material from the lithium ion battery positive electrode material according to the present invention, the input amount of the positive electrode material to the space capacity of the impact mill is 125 to 375 kg / m 3.

In yet another embodiment of the method for separating and collecting the current collector and the positive electrode active material from the lithium ion battery positive electrode material according to the present invention, the cutting of the step (B) is carried out above the sieve in the step (C), Process (B) and process (C) are performed continuously.

In another embodiment of the method for separating and collecting the current collector and the positive electrode active material from the lithium ion battery positive electrode material according to the present invention, step (B) is performed by a uniaxial or biaxial crusher.

According to the present invention, the current collector and the positive electrode active material can be separated and recovered from the positive electrode material for lithium ion battery with high efficiency. The method according to the invention is useful, for example, when recycling a lithium ion battery. The method according to the present invention can be implemented in a simple facility configuration such as a grinding facility and a sieve, and the processing cost is lower than that of a wet treatment using a chemical or a combustion treatment handling a high temperature. Is also easy.

1 shows an example of a photomicrograph of a current collector obtained by step (D).

In one embodiment of the method of separating and recovering an electrical power collector and a positive electrode active material from the lithium ion battery positive electrode material which concerns on this invention,

(A) process of preparing the positive electrode material for lithium ion batteries which has a structure by which an electrical power collector and a positive electrode active material adhere | attach with a binder,

(B) cutting the positive electrode material for lithium ion battery;

(C) sifting the positive electrode material after cutting by a sieve having a scale of 100 to 200 mm, and recovering the positive electrode material under the sieve;

(D) a step of peeling the positive electrode active material from the current collector by applying an impact force to the positive electrode material under the sieve obtained in step (C),

(E) After the step (D), the positive electrode material is screened with a sieve having a scale of 0.1 to 1.0 mm, and a current collector is collected on the upper side of the sieve and a positive electrode active material is recovered on the lower side of the sieve.

≪ Process (A) >

In process (A), the positive electrode material for lithium ion batteries which has a structure by which an electrical power collector and a positive electrode active material adhere | attach with a binder is prepared. Although not limited, in a general positive electrode material, an electrode material including a positive electrode active material, a binder, and a conductive agent and an electrolyte, if necessary, is dispersed in a solvent to prepare a positive electrode active material slurry, and the positive electrode active material slurry is applied onto a current collector. After pressing to dry, the positive electrode active material is adhered to one or both surfaces of the current collector. In particular, the method according to the present invention includes a positive electrode material recovered from a used lithium ion battery, an out-of-standard positive electrode material generated during a manufacturing process, a positive electrode material for extraction inspection processing in quality control, and an end material generated during the manufacturing process. And the like can be particularly targeted.

As the current collector, although not limited, metals such as aluminum, copper, nickel, silver, gold, chromium, iron, tin, lead, tungsten, molybdenum, zinc or alloys containing them are usually used. It is used. The current collector is generally provided in the form of a metal foil. The method according to the present invention can be particularly suitably used for a positive electrode material using aluminum or an aluminum alloy as a current collector.

The positive electrode active material is not particularly limited as long as it is well known as a positive electrode active material for lithium ion batteries. Generally, a composite oxide containing any one or two or more of cobalt, nickel, manganese, titanium, vanadium, iron, and copper in addition to lithium. Or in the form of a salt.

Resin is generally used as a binder, but it is not limited to polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), styrene butadiene rubber (SBR), polyimide, polyamide, polyvinyl acetate, polychloride Vinyl (PVC), Polymethylacrylate (PMA), Polymethylmethacrylate (PMMA), Polyethernitrile (PEN), Polyethylene (PE), Polypropylene (PP), Polyacrylonitrile (PAN), Epoxy resin And polyurethane resins and urea resins. Typically PVDF is used.

≪ Process (B) >

In process (B), the positive electrode material for lithium ion batteries prepared in process (A) is cut out. In the said step, in order to improve the collection | recovery efficiency of the positive electrode material under a sieve in a process (C), in order to input into an apparatus which isolate | separates and collects an electrical power collector and a positive electrode active material by a physical and mechanical method, the positive electrode material is previously cut small. It is carried out for the purpose of. The mechanical impact applied to the positive electrode material at the time of cutting also weakens the adhesive strength between the positive electrode active material and the current collector. Although there is no restriction | limiting in the method of cutting | disconnection, For example, it can be put into a uniaxial or biaxial crusher, Preferably it can be put into a biaxial crusher.

As an important matter at the time of putting a positive electrode material into a crusher, the following is mentioned. In the step (B), if the cutting of the positive electrode active material from the current collector is suddenly performed and is cut too finely, the residence time in the crusher becomes long, and fine Al fragments are generated, and subsequent screening is performed. The problem that the content rate of Al which is an impurity in the positive electrode material under a sieve becomes large tends to arise. In addition, the scrap generated in the lithium ion battery manufacturing process has a roll-like thing, a thing which is piled up by the bundle shape, etc. exist, the form of a raw material is not uniform, and there are various sizes. As described above, while having different shapes and sizes, it is difficult to stably obtain good separation and recovery efficiency. In addition, in the case of fine cutting, limitation of the diameter of the inlet opening on the crusher side also occurs.

Therefore, in this step, it is preferable not to peel but to cut relatively largely, and to cut to the extent which passes the scale of a process (C). It is preferable to perform a process (B) and a process (C) continuously by performing cutting of a process (B) above the sieve in a process (C), and in that case, it does not cut too finely. For example, it is good to make positive electrode material smaller than the scale of a sieve continuously discharge from a crusher, without cutting | maintaining in a crusher for a long time, while cutting | disconnection using a sieve attached to a crusher.

In one embodiment, for a crusher, a biaxial shearing crusher with an output of 20 to 50 kW, typically an output of 30 to 40 kW (for example 37 kW) is used, and a feeding rate of 30 to 100 kg / min, typical Furnace can be treated at a feed rate of 50 to 60 kg / min (for example, 50 kg / min).

≪ Process (C) >

In the step (C), the positive electrode material after the cutting is sifted through a sieve in the step (B) to recover the positive electrode material under the sieve. The positive electrode material after cutting is passed through a sieve having a scale of 300 mm or less, preferably 200 mm or less, more preferably 100 to 200 mm, and the size of the positive electrode material is a certain size (for example, a dimension of about 20 to 100 mm). By adjusting to, high peeling efficiency of a positive electrode active material and an electrical power collector in a process (D) can be obtained. However, if the scale is made too small, since the size of the positive electrode material peeled from the current collector is large, many positive electrode materials will remain on the upper side of the sieve together with Al foil of the current collector, so that the scale of the sieve is preferably 50 mm or more, It is more preferable to set it as 100 mm or more. In this specification, the scale of a sieve is defined by JIS Z8801-1: 2006.

As a sieve which can be used at a process (C), a vibrating sieve, a stirring sieve, etc. are mentioned, for example, The sieve which has a structure of a vibrating sieve is preferable. As described above, the step (B) and the step (C) are preferably carried out in order to prevent cutting too finely.

≪ Process (D) >

The current collector and the positive electrode active material are peeled off by applying an impact force to the positive electrode material under the sieve obtained in the step (C). The impact force is thought to cause cracking to the positive electrode active material on the current collector, and furthermore, the impact force is continuously applied, so that the crack propagates and peeling occurs due to the positive electrode active material falling off the current collector. What is necessary is just to provide the impact force the magnitude | size and time just enough that a positive electrode active material peels from a collector. It is preferable that a crack generate | occur | produces in a positive electrode active material, and it may fall only from a collector, and a collector does not fracture. This is because the current collector needs to be separated from the positive electrode active material later by screening, and it is preferable that the current collector is kept as large as possible.

Therefore, the method of dropping the positive electrode active material from the current collector without destroying the positive electrode active material by impact force and greatly changing the size of the current collector is a process of miniaturizing the positive electrode active material together with the current collector by shearing, which is a general method. This is advantageous over the method of removing the positive electrode active material from the current collector.

As a means for imparting an impact force, although not limited, a crusher which breaks by impact or collision is preferable. For example, a device in which the input of raw materials is a batch or continuous type, and the injected material is placed in a space to be crushed. And a device having one or more rotary crushing teeth. The rotary crushing device is suitable for imparting multiple impacts for one second and imparting impact force to the positive electrode material. As such an apparatus, impact mills, such as a sample mill, a hammer mill, a pin mill, and a knife mill, are preferable, and a hammer mill is more preferable.

If the input weight per dose is small, the throughput is small, and if it is too large, the positive electrode material is hardened by crushing and hardening in the inside of the mill apparatus, so that the input amount of the positive electrode material to the space capacity of the mill is 125 to 375 kg / m 3. It is preferable to inject ash into a mill, and it is more preferable to inject a positive electrode material into a mill as 150-250 kg / m <3>. Here, the space capacity of the mill refers to the capacity of the space in which the injected material is subjected to grinding.

The rotational speed of the crushing can be, for example, 3000 rpm or more, preferably 5000 rpm or more, and 30 to 80 m / s, preferably 60 to 70 m / s, and 5 to 60 Seconds, preferably a residence time of 15 to 30 seconds.

The following matters are important when giving a shear stress to a positive electrode material. By increasing the number of times of contacting and colliding with the positive electrode material per second, the number of times of applying the shearing force increases, and the direction of the force applied is not one-dimensional but three-dimensional, so that the positive electrode material is microscopic and many uneven It can confirm by a photograph (FIG. 1), and the peelability of the positive electrode active material from an electrical power collector improves. For example, in the case of rotary teeth, the condition can be satisfied by raising the rotation speed.

In one embodiment, as for the positive electrode material obtained by process (D) (actually the electrical power collector which peeled off the positive electrode active material), several unevenness | corrugation per 1 mm <2> of observation field exists, Preferably it is ten or more, Typically there are 15 to 30 unevennesses on average. The number of the irregularities is visually measured by an optical microscope.

According to the present invention, after the step (D), the proportion of the positive electrode active material adhered without peeling from the current collector can be 10% or less, preferably 5% or less, and more preferably 3%. It can be set as follows.

When the positive electrode materials of various sizes are treated simultaneously without adjusting the dimensions of the positive electrode materials in advance, the shear stress and time necessary for peeling the positive electrode active material from the current collector are varied. In particular, when a positive electrode material having a large size is mixed, a long time is required for peeling, and the separation efficiency is also deteriorated. Therefore, the separation efficiency by a grinder fluctuates greatly by the distribution conditions of the magnitude | size of the positive electrode material thrown in, and a stable separation efficiency is not obtained. By the way, in this invention, since the positive electrode material adjusted to the magnitude | size which is easy to peel in advance will receive process (D), high separation efficiency will be obtained stably.

&Lt; Process (E) >

After the step (D), the positive electrode material is sifted, and a step (E) of collecting the current collector on the upper side and the positive electrode active material on the lower side of the sieve is performed. When the magnitude | size of the electrical power collector isolate | separated by the process (D) and the positive electrode active material is compared, since the positive electrode active material peeled from the electrical power collector is granular, a collector is larger. Therefore, by using a sieve having an appropriate scale, the sifting of both can be performed with high separation efficiency.

If the scale of the sieve used in the step (E) is too small, the amount of the positive electrode active material shifted to the upper side of the sieve increases, while if the scale of the sieve is too small, the amount of the current collector transferred to the lower sieve increases. Therefore, the appropriate scale of the sieve is 0.1-1.0 mm, Preferably it is 0.25-0.5 mm, More preferably, it is 0.2-0.3 mm.

According to the present invention, before and after the step (E), the mass ratio of the current collector recovered on the sieve side can be 90% or more, preferably 95% or more, and more preferably 99% or more. It can be set as it, for example, it can be 90 to 100%. The said ratio is represented by (mass of the collector component collect | recovered on the sieve upper side after a process (E)) / (mass of the collector component contained in the positive electrode material immediately before a process (E)) x 100 (%). .

According to this invention, before and after a process (E), the mass ratio of the metal component of the positive electrode active material collect | recovered under a sieve can be 80% or more, Preferably it can be 85% or more, for example, 85 To 91%. The said ratio is (mass of the metal component of the positive electrode active material collect | recovered under the sieve after process (E)) / (mass of the metal component of the positive electrode active material contained in the positive electrode material immediately before process (E)) x 100 (% Is represented by).

Example

Hereinafter, embodiments of the present invention will be described, but the embodiments are for illustrative purposes and are not intended to limit the invention. In Examples, the analysis of metals was carried out by measurement by an ICP emission spectrophotometer by aqua regia dissolution.

A positive electrode material for lithium ion batteries using aluminum foil as a current collector and PVDF as a binder was prepared.

The positive electrode material was cut into 12 rounds / min, 50 kg / min, and an output of 37 kV by a biaxial shearing type crusher having a vibrating body having a scale of 100 mm below the crushed teeth.

Subsequently, the positive electrode material collected below the sieve was thrown into the hammer mill at the input amount with respect to the space capacity of 375 kg / m <3>, and peeling process was performed on the conditions of rotation speed 3000rpm or more, circumferential speed 60m / s, and residence time 15 second. When arbitrary ten pieces of the obtained positive electrode material (actually, the current collector in which the positive electrode active material was peeled off) were measured by an optical microscope, 26 irregularities existed on average per 1 mm 2 of the observation field.

When the positive electrode material after peeling process was analyzed, the metal component of Table 1 was detected. The positive electrode material was scaled according to the sample and screened with a vibrating sieve, whereby the results shown in Table 2 were obtained. Although there is an analysis error, from the analysis value of the sieve sample, the positive electrode active material attached without peeling from the aluminum foil is estimated to be about 2%.

[Table 1]

TABLE 2-1

Table 2-2

Claims (7)

(A) process of preparing the positive electrode material for lithium ion batteries which has a structure by which an electrical power collector and a positive electrode active material adhere | attach with a binder,
(B) cutting the positive electrode material for lithium ion battery;
(C) sifting the positive electrode material after cutting by a sieve having a scale of 100 to 200 mm, and recovering the positive electrode material under the sieve;
(D) a step of peeling the positive electrode active material from the current collector by applying an impact force to the positive electrode material under the sieve obtained in step (C),
(E) After the step (D), the positive electrode material is screened by a sieve having a scale of 0.1 to 1.0 mm, and the current collector is collected from the upper part of the sieve, and the positive electrode active material is collected from the lower part of the sieve. Method for separating and recovering the whole and the positive electrode active material. The positive electrode material obtained by the process (D) is a method of separating and collecting a current collector and a positive electrode active material from the positive electrode material for lithium ion batteries in which several unevenness | corrugation exists per 1 mm <2> of observation visual fields. The method for separating and collecting the current collector and the positive electrode active material from the positive electrode material for a lithium ion battery according to claim 1 or 2, wherein the step (D) is performed by an impact mill. The method of separating and recovering a current collector and a positive electrode active material from the positive electrode material for lithium ion batteries of Claim 3 whose impact mill is a hammer mill. The method of separating and recovering a current collector and a positive electrode active material from the positive electrode material for lithium ion batteries of Claim 3 which is 125-375 kg / m <3> of input of the positive electrode material with respect to the space capacity of an impact mill. The positive electrode material for lithium ion batteries according to claim 1 or 2, wherein the cutting of the step (B) is performed above the sieve in the step (C) to continuously perform the step (B) and the step (C). A method for separating and collecting a current collector and a positive electrode active material from a. The method for separating and collecting the current collector and the positive electrode active material from the positive electrode material for a lithium ion battery according to claim 1 or 2, wherein the step (B) is performed by a uniaxial or biaxial crusher.

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