JP5011659B2 - Battery recycling method - Google Patents

Description

  The present invention relates to a battery recycling method, and more particularly, to a battery recycling method including an electrode having an electrode base material and an active material layer that includes an active material and a binder resin and is fixed to the electrode base material.

  In recent years, various methods have been proposed as a battery recycling method including an electrode substrate and an electrode including an active material and a binder resin, and an active material layer fixed to the electrode substrate (for example, Patent Documents). 1 and 2).

JP 2001-23704 A JP-A-10-255862

  Patent document 1 is a document regarding the recycling method of a lithium ion battery. Specifically, the electrode package is pulverized and sieved, and this is heat-treated at a high temperature of 300 to 700 ° C., whereby the binder resin is thermally decomposed to obtain an active material (specifically, lithium and transition metal). And a method for recovering the mixed oxide).

  Patent Document 2 is also a document related to a method for recycling a lithium ion battery. Specifically, by immersing the electrode in an acidic solution or the like, it is separated into an electrode material (an active material layer including an active material and a binder resin) and a current collector (an electrode base material such as an aluminum foil or a copper foil). And the method of collect | recovering electrical power collectors (electrode base materials, such as aluminum foil and copper foil), is proposed.

  Furthermore, as a method for recovering the active material, only a method for recovering the positive electrode active material (specifically, a mixed oxide of lithium and a transition metal) is described. Specifically, a method of recovering the positive electrode active material by evaporating the binder resin by heat-treating the electrode material (the active material layer containing the active material and the binder resin) is exemplified. Separately, the electrode material (active material layer including active material and binder resin) is treated with an acidic solution (hydrochloric acid, nitric acid, etc.), etc., so that only the positive electrode active material is dissolved and separated from the binder resin. The method of doing is also illustrated.

  However, in the method of Patent Document 1, electrode materials other than the active material (for example, electrode base materials such as copper foil) cannot be collected and reused. Moreover, in the method of heat-treating the electrode material illustrated at Patent Document 1 and Patent Document 2 at a high temperature, the active material (specifically, a mixed oxide of lithium and a transition metal) has a fine structure. There was a risk of destruction. For this reason, there was a possibility that the active material could not be reused.

Moreover, the recovery method of the positive electrode active material which processes the electrode material by acidic solution (hydrochloric acid, nitric acid, etc.) illustrated by patent document 2 is binder resin (for example, cellulose easily dissolved in acidic solution) as binder resin. In the case of containing an aqueous binder resin such as
Moreover, since it is not described about the collection method of a negative electrode active material, it is unknown. In the lithium ion battery, carbon is generally used as the negative electrode active material. However, since carbon does not dissolve in an acidic solution, the above recovery method cannot be used.

  This invention is made | formed in view of this present condition, Comprising: It aims at providing the recycling method of the battery which can reuse an active material appropriately.

The solution is a battery recycling method comprising an electrode substrate and an electrode comprising an active material and a binder resin, and an active material layer fixed to the electrode substrate, wherein the active material layer comprises: The aqueous binder resin is contained as the binder resin, and the active material layer separated from the electrode base material is heated together with an acidic aqueous solution to hydrolyze the aqueous binder resin, thereby converting the active material into the aqueous binder. active material separation step of separating from the resin, have a, the electrode substrate is made of copper, the prior to the active material separation process, by a hydrochloric acid treatment, the electrode, the the above electrode substrate active material layer and The active material separation step includes a heating step in which the active material layer separated in the electrode separation step is immersed in water and heated while hydrochloric acid is attached. No is a battery of recycling method.

  In the recycling method of the present invention, the active material layer separated from the electrode base material is heated together with an acidic aqueous solution to hydrolyze the aqueous binder resin, thereby separating the active material from the aqueous binder resin. Have. Since the hydrolysis of the aqueous binder can be promoted by heating the active material layer together with the acidic aqueous solution, the active material can be appropriately separated. Therefore, according to the recycling method of the present invention, the active material contained in the battery can be appropriately reused.

The aqueous binder resin refers to a binder resin using water as a solvent, and examples thereof include CMC (carboxymethyl cellulose) and PVA (polyvinyl alcohol).
Further, the recycling method of the present invention can be applied not only to the secondary battery but also to the recycling of the primary battery as long as the battery has an electrode in which the active material is fixed to the electrode base material using an aqueous binder resin. it can.

The recycling method of the present invention is a preferable recycling method for a battery having a copper electrode substrate.
Specifically, an electrode separation step of separating the electrode into a copper electrode base material and an active material layer by hydrochloric acid treatment is provided. By using hydrochloric acid, it is possible to appropriately separate the electrode base material and the active material layer without dissolving the copper electrode base material. In addition, the active material layer can be separated (peeled) from the electrode substrate more quickly than in the case of using another acidic aqueous solution such as oxalic acid. Thereby, the copper electrode base material can be reused efficiently.

  Furthermore, the recycling method of the present invention includes a heating step in which the active material layer separated in the electrode separation step is heated while being immersed in water with hydrochloric acid attached. Since the active material layer is separated using hydrochloric acid in the electrode separation step, the active material layer in the electrode separation step is in a state where hydrochloric acid is attached. Therefore, in the active material separation step of the present invention, hydrochloric acid attached to the active material layer is used in the heating step. That is, without preparing hydrochloric acid separately in the heating step, the active material layer separated in the electrode separation step is immersed in water while the hydrochloric acid is attached, so that the active material layer is immersed in hydrochloric acid. Can be.

Therefore, since the hydrolysis of the aqueous binder can be promoted by immersing the active material layer in water and heating it, the active material can be separated quickly.
In addition, as an electrode containing a copper electrode base material, the negative electrode of a lithium ion secondary battery, etc. can be illustrated.

Another solution is a battery recycling method comprising an electrode substrate and an electrode comprising an active material and a binder resin, and an active material layer fixed to the electrode substrate, wherein the active material layer Includes a solvent-based binder resin as the binder resin, and heats the active material layer separated from the electrode substrate together with an organic solvent to separate the active material from the solvent-based binder resin. An organic solvent in which the difference between the solubility parameter of the solvent and the solubility parameter of the solvent-based binder resin is less than 2.2 (MPa) ^{1/2 as} the organic solvent. There use, said active material layer, as the solvent binder resin comprises a non-polar solvent-based binder resin, the active material separation process, as the organic solvent, the battery using a non-polar organic solvent Lisa It is an inclement method.

In the active material separation step of the present invention, an organic solvent in which the difference between the solubility parameter of the solvent and the solubility parameter of the solvent-based binder resin is less than 2.2 (MPa) ^1/2 is used as the organic solvent. By mixing and heating a solvent-based binder resin and an organic solvent having a solubility parameter difference of less than 2.2 (MPa) ^1/2 , the solvent-based binder resin can be appropriately swollen or dissolved. Thereby, the active material can be separated from the solvent-based binder resin.

The solubility parameter is a value indicating the solubility of a substance and serves as an index of the affinity between the solvent and the resin. Specifically, the closer the solubility parameter value between the solvent and the resin is (the smaller the difference), the better the solubility of the resin in the solvent. In the present specification, the value of the solubility parameter is expressed in terms of 1 (cal / cm ³ ) ^1/2 = 2.046 (MPa) ^1/2 .
The solvent-based binder resin refers to a binder resin using an organic solvent as a solvent, such as PVDF (polyvinylidene fluoride), PBT (poly-P-phenylenebenzobisoxazole), PTFE (polytetrafluoroethylene), and the like. It can be illustrated.

In the recycling method of the present invention, a nonpolar organic solvent is used as the organic solvent in the active material separation step for the active material layer containing the nonpolar solvent-based binder resin. That is, the active material layer containing the nonpolar solvent-based binder resin is heated together with the nonpolar organic solvent to separate the active material from the nonpolar solvent-based binder resin. By heating a non-polar solvent-based binder resin together with a non-polar organic solvent (difference in solubility parameter from the above-mentioned binder resin is less than 2.2 (MPa) ^1/2 ), the solvent-based binder resin is appropriately Can be dissolved. Therefore, the active material can be appropriately separated from the nonpolar solvent-based binder resin.

  Examples of the nonpolar solvent-based binder resin include PVDF (polyvinylidene fluoride) and PTFE (polytetrafluoroethylene). As the nonpolar organic solvent, for example, acetone, O-dichlorobenzene, 1,2-dichloroethylene, tetrahydrofuran, NMP (N-methylpyrrolidone), trichloroethylene, or the like can be used.

Another solution is a battery recycling method comprising an electrode substrate and an electrode comprising an active material and a binder resin, and an active material layer fixed to the electrode substrate, wherein the active material layer Includes a solvent-based binder resin as the binder resin, and heats the active material layer separated from the electrode substrate together with an organic solvent to separate the active material from the solvent-based binder resin. An organic solvent in which the difference between the solubility parameter of the solvent and the solubility parameter of the solvent-based binder resin is less than 2.2 (MPa) ^{1/2 as} the organic solvent. The active material layer includes a solvent-based binder resin having polarity as the solvent-based binder resin, and the active material separation step uses an organic solvent having polarity as the organic solvent. Recycling method of pond.

In the recycling method of the present invention, an organic solvent having polarity is used as the organic solvent in the active material separation step for the active material layer containing the solvent-based binder resin having polarity. That is, the active material layer containing the solvent-based binder resin having polarity is heated together with the organic solvent having polarity to separate the active material from the solvent-based binder resin having polarity. By heating the solvent-based binder resin having polarity with an organic solvent having polarity (the difference in solubility parameter from the binder resin is less than 2.2 (MPa) ^1/2 ), the solvent-based binder resin is appropriately Can be dissolved. For this reason, the active material can be appropriately separated from the solvent-based binder resin having polarity.

  Examples of the solvent-based binder resin having polarity include PBT (poly-P-phenylene benzobisoxazole), PC (polycarbonate), and PAN (polyacrylonitrile). Examples of polar organic solvents that can be used include chlorophenol, ethanol, methyl ethyl ketone, and methyl acetate.

Next, embodiments (Examples 1 to 3 ) of the present invention will be described with reference to the drawings.
Example 1
First, before describing the recycling method of the first embodiment, the battery 100 to be recycled will be described. 1A and 1B are diagrams showing a battery 100, where FIG. 1A is a front view and FIG. 1B is a side view. FIG. 2 is a cross-sectional view of the battery 100 and corresponds to the AA cross-sectional view of FIG. However, in FIG. 2, illustration of the positive electrode terminal 120, the negative electrode terminal 130, etc. is omitted.

  As shown in FIG. 1, the battery 100 is a sealed lithium ion secondary battery including a rectangular parallelepiped battery case 110, a positive electrode terminal 120, and a negative electrode terminal 130. Among these, as shown in FIG. 2, the battery case 110 is made of metal, and includes a rectangular accommodating portion 111 that forms a rectangular parallelepiped accommodating space, and a metal lid portion 112. A flat wound body 150 and an electrolyte solution (not shown) are arranged inside the battery case 110 (rectangular housing part 111).

  The flat wound body 150 is a flat wound body that is formed by winding a sheet-like positive electrode 155, a negative electrode 156, and a separator 157. Among these, the positive electrode 155 has a sheet-like positive electrode substrate made of aluminum, and a positive electrode active material layer that includes a positive electrode active material and a binder resin and is coated on the surface of the positive electrode substrate. The negative electrode 156 includes a sheet-like negative electrode substrate made of copper, and a negative electrode active material layer that includes a negative electrode active material and a binder resin and is coated on the surface of the negative electrode substrate.

In the battery 100, CMC (carboxymethyl cellulose) which is a water-based binder resin is used as the binder resin of the negative electrode active material layer. Further, carbon powder having an average particle size of 5 μm is used as the negative electrode active material. As the electrolytic solution, a nonaqueous electrolytic solution in which lithium hexafluorophosphate (LiPF ₆ ) is dissolved in a mixed solvent of ethylene carbonate, propylene carbonate, and 1,2 dimethoxyethane is used.

  Although not shown, a positive electrode lead is connected to one end portion of the flat wound body 150 (an unfilled portion not filled with the positive electrode active material) of the positive electrode 155. The other end of the positive electrode lead (not shown) is connected to the positive electrode terminal 120, whereby the positive electrode 155 and the positive electrode terminal 120 are electrically connected. Similarly, a negative electrode lead (not shown) is connected to one end of the negative electrode 155 (an unfilled portion not filled with the negative electrode active material). The other end of the negative electrode lead is connected to the negative electrode terminal 130, whereby the negative electrode 155 and the negative electrode terminal 130 are electrically connected.

Next, a method for recycling the battery 100 (waste battery) will be described with reference to the flowchart of FIG.
First, a battery 100 (waste battery) that has been consumed (used) due to its life is prepared. Next, in step S1, the battery 100 is discharged. Next, the process proceeds to step S2, and the wound body 150 (the positive electrode 155 and the negative electrode 156) is washed with an organic solvent (for example, acetone). Specifically, a through-hole is formed in the lid portion 112 of the battery case 110, and an organic solvent (acetone or the like) is injected into the battery case 110 through the through-hole. The operation of removing the battery from the battery case 110 is repeated a plurality of times. Thereby, electrolyte solution can be removed from the winding body 150 (the positive electrode 155 and the negative electrode 156).

  Next, the process proceeds to step S3, and a known method (for example, Masaaki Hosomi: Safety Engineering vol.40 No.6 p420 (2001)) is obtained from a mixed solution of an organic solvent (acetone, etc.) taken out from the battery case 110 and the electrolyte. Extract the electrolyte solution. Specifically, after the mixed solution is put into the vacuum processing chamber, it is sealed, decompressed to 10 mbar, gradually heated to 750 ° C, and the electrolyte is separated using the difference in boiling point between the electrolyte and the organic solvent. to recover. The electrolytic solution thus obtained can be reused as an electrolytic solution for a newly manufactured battery.

  Next, the process proceeds to step S <b> 4, where the battery case 110 is cut and separated into the square housing part 111 and the lid part 112. Subsequently, it progresses to step S5 and takes out the winding body 150 from the battery case 110 (square accommodation part 111). Then, it progresses to step S6 and the winding body 150 is dried. In addition, since the positive electrode lead and the negative electrode lead are connected to the wound body 150, they are removed from the wound body 150 before drying. Next, the process proceeds to step S7, where the wound body 150 is mechanically separated into the positive electrode 155, the negative electrode 156, and the separator 157, and the negative electrode 156 is taken out.

  Next, in step S8, the negative electrode 156 is immersed in a hydrochloric acid solution (hydrochloric acid treatment), and separated into a negative electrode substrate (copper foil) and a negative electrode active material layer (negative electrode active material and binder resin). Specifically, the negative electrode 156 was immersed in a hydrochloric acid solution adjusted to a concentration of 6 (mol / l) at room temperature for about 5 minutes. Thus, by immersing the negative electrode 156 in a hydrochloric acid solution (hydrochloric acid treatment), the negative electrode active material layer (negative electrode active material and binder resin) can be cleanly peeled from the negative electrode substrate (copper foil). Moreover, in Example 1, since hydrochloric acid is used for the negative electrode including the negative electrode base material made of copper, the negative electrode base material (copper foil) and the negative electrode active material are not dissolved without dissolving the negative electrode base material (copper foil). It can be separated into a material layer (negative electrode active material and binder resin).

Thus, since a negative electrode base material (copper foil) is not dissolved, the recovery rate of a negative electrode base material (copper foil) can be raised, and also a negative electrode base material (copper foil) can be collect | recovered easily.
In step S8, when lithium is contained in the negative electrode active material layer, the lithium can be desorbed from the negative electrode active material layer as lithium ions.
In the first embodiment, step S8 corresponds to an electrode separation process.

  Subsequently, it progresses to step S9 and a negative electrode base material (copper foil) is taken out from hydrochloric acid solution. Subsequently, it progresses to step SA and this negative electrode base material (copper foil) is wash | cleaned with water, and is dried. Then, it progresses to step SB and a negative electrode base material (copper foil) is wound. When the surface of the negative electrode base material (copper foil) collected in this manner was examined, the negative electrode active material (carbon) and the binder resin (CMC) were not attached at all. For this reason, the negative electrode base material (copper foil) recovered by the recycling method of Example 1 can be reused as the negative electrode base material (copper foil) of a newly manufactured battery.

  In addition to the processing of Steps S9 to SB described above, after performing the processing of Step S8, the process proceeds to Step SC, and the negative electrode active material layer (negative electrode active material and binder resin) is taken out from the hydrochloric acid solution. Subsequently, it progresses to step SD and the negative electrode active material layer taken out from the hydrochloric acid solution is immersed in water and heated while the hydrochloric acid is adhered. As a result, CMC (carboxymethylcellulose), which is an aqueous binder resin contained in the negative electrode active material layer, can be hydrolyzed, so that the negative electrode active material (carbon powder) joined via CMC (carboxymethylcellulose). Can be separated.

By the way, in Example 1, since the negative electrode active material layer was separated using hydrochloric acid in Step S8, in Step SC, the negative electrode active material layer taken out from the hydrochloric acid solution was in a state where hydrochloric acid was adhered. ing. For this reason, in Step SD, the negative electrode active material layer taken out from the hydrochloric acid solution is immersed in water while the hydrochloric acid is adhered, so that the negative electrode active material layer is immersed in hydrochloric acid (dilute hydrochloric acid). be able to. Therefore, in Step SD, the negative electrode active material layer is heated together with the acidic aqueous solution (dilute hydrochloric acid), so that hydrolysis of CMC (carboxymethylcellulose) can be promoted and the negative electrode active material can be separated quickly.
In Example 1, step SD corresponds to the active material separation step.

Next, it progresses to step SE and takes out a negative electrode active material (carbon powder) from the solution which CMC (glucose etc.) and negative electrode active material (carbon powder) isolate | separated from. Specifically, by utilizing the difference in specific gravity between hydrolyzed CMC (such as glucose) and the negative electrode active material (carbon powder), the negative electrode active material having a low specific gravity is precipitated by precipitating hydrolyzed CMC having a large specific gravity. (Carbon powder) can be taken out.
Subsequently, it progresses to step SF and heat-processes a negative electrode active material (carbon powder) at the temperature of 600-3000 degreeC. Subsequently, it progresses to step SG, the negative electrode active material (carbon powder) which heat-processed is sieved, and negative electrode active materials (carbon powder) with an average particle diameter of 5 micrometers are collect | recovered.

Here, the result of analyzing the crystal structure of the recovered negative electrode active material (carbon powder) and the unused (new) negative electrode active material (carbon powder) by X-ray diffraction is shown in FIG. 5A is an X-ray diffraction pattern of an unused (new) negative electrode active material (carbon powder), and FIG. 5B is a negative electrode active material (carbon powder) recovered by the recycling method of Example 1. FIG. As can be seen by comparing FIGS. 5A and 5B, it can be said that the crystal structures of both are almost the same. That is, it can be said that the negative electrode active material (carbon powder) recovered by the recycling method of Example 1 is equivalent to an unused (new) negative electrode active material (carbon powder).
Therefore, the negative electrode active material (carbon powder) recovered by the recycling method of Example 1 can be reused as the negative electrode active material (carbon powder) of a newly manufactured battery.

  In step S7, the wound body 150 is mechanically separated into the positive electrode 155, the negative electrode 156, and the separator 157, and after the negative electrode 156 is taken out, the positive electrode 155 is also subjected to a predetermined treatment, and the positive electrode substrate ( Aluminum foil) and the positive electrode active material are recovered. Specifically, the positive electrode substrate 155 (aluminum foil) and the positive electrode active material layer are separated into a positive electrode substrate (aluminum foil) by immersing the positive electrode 155 in an acidic aqueous solution (such as nitric acid) using a known method. Foil) is collected. Next, after immersing the positive electrode active material layer in an acidic solution (hydrochloric acid or the like) to dissolve the positive electrode active material, the solution is filtered to obtain a metal ion mixed solution containing lithium, nickel and the like. Next, each metal is recovered from this mixed solution using techniques such as ion exchange, electrolysis, and precipitation separation.

  As described above, according to the recycling method of the first embodiment, the active material can be appropriately recovered from the discarded battery and reused. Specifically, the negative electrode active material (carbon powder) can be appropriately recovered and reused from the negative electrode having a negative electrode active material layer containing an aqueous binder resin. Moreover, since the negative electrode base material (copper foil) and the negative electrode active material layer are separated using hydrochloric acid, the negative electrode base material (copper foil) can be quickly and without dissolving the negative electrode base material (copper foil). Can be recovered and reused. In addition, since the negative electrode active material layer is immersed in water and heated while hydrochloric acid is adhered, the aqueous binder resin can be quickly hydrolyzed and a reusable negative electrode active material (carbon powder) can be recovered. Can do.

( Reference Example 1 )
In Example 1, in Step S8, the negative electrode 156 was separated into a negative electrode base material (copper foil) and a negative electrode active material layer (negative electrode active material and binder resin) using hydrochloric acid. On the other hand, in this reference example 1 , step S8A is provided instead of step S8, and using oxalic acid, the negative electrode 156, the negative electrode base material (copper foil), the negative electrode active material layer (negative electrode active material and binder resin), Separated. The recycling method of the reference example 1 is different from the recycling method of the example 1 in that step S8A is provided instead of step S8, and the other processes are the same.

Specifically, in step S8A, the negative electrode 156 is immersed in an oxalic acid solution adjusted to a concentration of 6 wt% at room temperature, and a negative electrode substrate (copper foil) and a negative electrode active material layer (negative electrode active material and binder) are immersed. Resin). Also in this reference example 1 , the negative electrode active material layer (negative electrode active material and binder resin) could be peeled cleanly from the negative electrode substrate (copper foil). However, since oxalic acid was used for the negative electrode including the negative electrode substrate made of copper, the negative electrode substrate (copper foil) was slightly dissolved. Moreover, it took a long time to peel off the negative electrode active material layer (negative electrode active material and binder resin) as compared with Example 1 using hydrochloric acid. Specifically, in Example 1, the negative electrode active material layer (negative electrode active material and binder resin) could be removed in about 5 minutes, whereas in Reference Example 1 , it took about 15 minutes.

Here, in FIG. 4, when the negative electrode 156 is treated with hydrochloric acid (indicated by black circles in the figure) and when oxalic acid is treated (indicated by triangular marks in the figure), the immersion time (minutes) and the negative electrode The relationship with the recovery rate (%) of the active material layer is shown. FIG. 4 shows the test results obtained by immersing a test piece obtained by molding the negative electrode 156 into a size of 5 cm × 5 cm in a hydrochloric acid solution or an oxalic acid solution, respectively.
As shown in FIG. 4, when hydrochloric acid is used, the negative electrode active material layer is immediately peeled off from the negative electrode base material, and after about 4 minutes, almost 100% of the negative electrode active material layer is peeled off (collected). I was able to. On the other hand, when oxalic acid is used, the progress of peeling of the negative electrode active material layer is slower than when hydrochloric acid is used, and about 100% of the negative electrode active material layer is peeled off (recovered) until approximately 100%. I spent 15 minutes.

In Reference Example 1 as well, in Step SD, the negative electrode active material layer taken out from the oxalic acid solution is immersed in water and heated while the oxalic acid is attached. Thereby, like Example 1, CMC (carboxymethylcellulose) which is an aqueous binder resin contained in the negative electrode active material layer can be rapidly hydrolyzed. Therefore, the negative electrode active material (carbon powder) bonded via CMC can be separated quickly and appropriately. Thereafter, in the same manner as in Example 1, the negative electrode active material (carbon powder) having the same quality as that of Example 1 could be recovered by performing the processes of Steps SE to SG.

As mentioned above, when the recycling method of Example 1 and Reference Example 1 is compared, in Step S8A (electrode separation step) of Reference Example 1 , the negative electrode base material (copper foil) has been dissolved by using oxalic acid. . On the other hand, in step S8 (electrode separation process) of Example 1, by using hydrochloric acid, the negative electrode base material (copper foil) was not dissolved and the negative electrode active material layer was rapidly removed from the negative electrode base material. Could be peeled off. Therefore, in the electrode separation step, it can be said that the recycling method of Example 1 using hydrochloric acid is a better technique than Reference Example 1 using oxalic acid.

( Example 2 )
In Example 1, the recycling method for the battery 100 in which CMC (carboxymethylcellulose), which is an aqueous binder resin, was used as the binder resin of the negative electrode active material layer was shown. In contrast, the second embodiment shows a recycling method for the battery 200 in which PVDF (polyvinylidene fluoride), which is a solvent-based binder resin, is used as the binder resin of the negative electrode active material layer. Specifically, in the recycling method of the second embodiment , the processing up to step SC is the same as in the first embodiment, but the subsequent processing is different.

First, before describing the recycling method of the second embodiment , the battery 200 to be recycled will be described. As shown in FIG. 2, the battery 200 is different from the battery 100 only in that it has a wound body 250 including a negative electrode 256 instead of the negative electrode 156. This negative electrode 256 differs from the negative electrode 156 of the battery 100 only in the binder resin of the negative electrode active material layer. Specifically, in the battery 200, PVDF (polyvinylidene fluoride) which is a solvent-based binder resin is used as the binder resin of the negative electrode active material layer. PVDF (polyvinylidene fluoride) is a non-polar binder resin, and its solubility parameter value (hereinafter also referred to as SP value) is 9.1 (cal / cm ³ ) ^1/2 = 18.6. (MPa) ^1/2 .

Next, a method for recycling the battery 200 (waste battery) will be described with reference to the flowchart of FIG.
First, a battery 200 (waste battery) that has been consumed (used) due to its lifetime is prepared. Next, in the same manner as in Example 1, the above-described steps S1 to SC were performed, and the wound negative electrode base material (copper foil) was recovered (step SB) and peeled off from the negative electrode base material (copper foil). The negative electrode active material layer is taken out (Step SC).

Next, proceeding to step TD, the negative electrode active material layer taken out from the hydrochloric acid solution is washed with distilled water, immersed in an organic solvent and heated.
In Example 2 , as the organic solvent, a nonpolar organic solvent having a solubility parameter difference of less than 2.2 (MPa) ^1/2 with PVDF (polyvinylidene fluoride) which is a nonpolar binder resin. Is used. Specifically, acetone (SP value is 9.9 (cal / cm ³ ) ^1/2 = 20.3 (MPa) ^1/2 ), 1,2-dichloroethylene (SP value is 9.7 (cal / Cm ³ ) ^1/2 = 19.9 (MPa) ^1/2 ), tetrahydrofuran (SP value is 9.3 (cal / cm ³ ) ^1/2 = 19.0 (MPa) ^1/2 ), trichlorethylene (SP value can be 9.2 (cal / cm ³ ) ^1/2 = 18.8 (MPa) ^1/2 ) or the like.

  By immersing the negative electrode active material layer in the organic solvent and heating, the PVDF (polyvinylidene fluoride) as the binder resin can be appropriately dissolved. Thereby, a negative electrode active material (carbon powder) can be appropriately separated from PVDF (polyvinylidene fluoride).

Subsequently, it progresses to step TE and takes out a negative electrode active material (carbon powder) from the solution which PVDF (polyvinylidene fluoride) and the negative electrode active material (carbon powder) isolate | separated. Specifically, a negative electrode active material (carbon powder) having a small specific gravity can be taken out by precipitating PVDF having a large specific gravity in the same manner as in Step SE of Example 1. In addition, when the taken-out negative electrode active material (carbon powder) was investigated, the negative electrode active material which the impurity adhered to the surface was hardly found.
Next, the process proceeds to Step TF, and the negative electrode active material (carbon powder) is washed with a nonpolar organic solvent (for example, acetone). Thereby, even when impurities are slightly attached to the surface of the negative electrode active material (carbon powder), it can be appropriately removed.

Subsequently, it progresses to step TG and heat-processes a negative electrode active material (carbon powder) at the temperature of 600-3000 degreeC similarly to step SF of Example 1. FIG. Next, the process proceeds to step TH, and the negative electrode active material (carbon powder) subjected to the heat treatment is sieved in the same manner as in step SG of Example 1, and the negative electrode active material (carbon powder) having an average particle diameter of 5 μm is recovered. The negative electrode active material (carbon powder) collected in this way was the same as the unused (new) negative electrode active material (carbon powder) in the same manner as the negative electrode active material collected in Example 1.
Therefore, the negative electrode active material (carbon powder) recovered by the recycling method of Example 2 can be reused as the negative electrode active material (carbon powder) of a newly manufactured battery.

( Reference Example 2 )
In Example 2 , the difference in solubility parameter (SP value) with PVDF (polyvinylidene fluoride), which is a nonpolar binder resin, is less than 2.2 (MPa) ^1/2 as an organic solvent in Step TD. A nonpolar organic solvent was used. On the other hand, in this reference example 2 , although the difference of SP value with PVDF is less than 2.2 (MPa) ^1/2 as an organic solvent, the organic solvent which has polarity is used. Specifically, methyl ethyl ketone (SP value is 9.3 (cal / cm ³ ) ^1/2 = 19.0 (MPa) ^1/2 ) or the like can be used as the organic solvent.
Note that the recycling method of the present Reference Example 2 is different from the recycling method of Example 2 only in the process of Step TD, and the other processes are the same.

In Step TD of Reference Example 2 , PVDF (polyvinylidene fluoride), which is a binder resin, can be swollen by immersing the negative electrode active material layer in the organic solvent and heating. Thereby, a negative electrode active material (carbon powder) can be separated from PVDF (polyvinylidene fluoride).

By the way, as described above, in Example 2 , when the negative electrode active material (carbon powder) taken out in Step TE was examined, almost no negative electrode active material having impurities attached to its surface was found. However, in this reference example 2 , when the taken-out negative electrode active material (carbon powder) was investigated, many negative electrode active materials (carbon powder) had impurities adhered to the surface.

This is because the same nonpolar organic solvent was used in Example 2 for PVDF (polyvinylidene fluoride), which is a nonpolar binder resin, but in Example 2 , a polar organic solvent was used. it is conceivable that. According to the comparison between Example 2 and Reference Example 2 , even if the difference in SP value from the binder resin is less than 2.2 (MPa) ^1/2 , the solubility of PVDF varies greatly depending on the presence or absence of polarity. I understand. That is, when a nonpolar organic solvent is used, a negative electrode active material (carbon powder) free from impurities can be obtained by appropriately dissolving PVDF. On the other hand, when a polar organic solvent is used, PVDF cannot be dissolved and remains swollen, so that impurities tend to remain on the surface of the negative electrode active material (carbon powder). It was.

However, in Reference Example 2 , in Step TF, the impurities adhered to the surface of the negative electrode active material (carbon powder) by washing the negative electrode active material (carbon powder) with a nonpolar organic solvent (acetone or the like). Can be removed appropriately. For this reason, the negative electrode active material (carbon powder) recovered by the recycling method of Reference Example 2 can also be reused as the negative electrode active material (carbon powder) of a newly produced battery.

( Example 3 )
In Example 2 , the recycling method was shown for the battery 200 in which PVDF (polyvinylidene fluoride), which is a nonpolar solvent-based binder resin, was used as the binder resin of the negative electrode active material layer. In contrast, the present Example 3 shows a recycling method for the battery 300 in which PC (polycarbonate), which is a solvent-based binder resin having polarity, is used as the binder resin of the negative electrode active material layer. Specifically, the recycling method of the third embodiment is different from the second embodiment in the type of organic solvent used in step TD and step TF, and the other is the same.

First, before describing the recycling method of the third embodiment , the battery 300 to be recycled will be described. As shown in FIG. 2, the battery 300 is different from the battery 200 only in that it has a wound body 350 including a negative electrode 356 instead of the negative electrode 256. This negative electrode 356 differs from the negative electrode 256 of the battery 200 only in the binder resin of the negative electrode active material layer. Specifically, in the battery 300, PC (polycarbonate) which is a solvent-based binder resin having polarity is used as the binder resin of the negative electrode active material layer. The value (SP value) of the solubility parameter of PC is 9.8 (cal / cm ³ ) ^1/2 = 20.1 (MPa) ^1/2 .

Next, a method for recycling the battery 300 (waste battery) will be described with reference to the flowchart of FIG.
First, a battery 200 (waste battery) that has been consumed (used) due to its lifetime is prepared. Next, in the same manner as in Examples 1 and 2 , the processes from Steps S1 to SC described above are performed, and the wound negative electrode base material (copper foil) is recovered (Step SB) and from the negative electrode base material (copper foil). The peeled negative electrode active material layer is taken out (step SC).

Next, it progresses to step TD and the negative electrode active material layer taken out from the hydrochloric acid solution is immersed in an organic solvent and heated. In Example 3 , the organic solvent having polarity, the difference in solubility parameter from PC (polycarbonate) which is a solvent-based binder resin having polarity is less than 2.2 (MPa) ^1/2 as the organic solvent. Is used. Specifically, methyl ethyl ketone (SP value is 9.3 (cal / cm ³ ) ^1/2 = 19.0 (MPa) ^1/2 ), methyl acetate (SP value is 9.6 (cal / cm ³⁾ ) ^1/2 = 19.6 (MPa) ^1/2 ) or the like.

  By immersing the negative electrode active material layer in the organic solvent and heating, the PC (polycarbonate) as the binder resin can be appropriately dissolved. Thereby, a negative electrode active material (carbon powder) can be appropriately separated from PC which is a binder resin.

Next, the process proceeds to step TE, and the negative electrode active material (carbon powder) is taken out from the solution in which the PC and the negative electrode active material (carbon powder) are separated. Specifically, a negative electrode active material (carbon powder) having a small specific gravity can be taken out by precipitating PC having a large specific gravity in the same manner as in Example 2 . In addition, when the taken-out negative electrode active material (carbon powder) was investigated, the negative electrode active material which the impurity adhered to the surface was hardly found. Next, the process proceeds to Step TF, and the negative electrode active material (carbon powder) is washed with a polar organic solvent (for example, ethanol). Thereby, even when impurities are slightly attached to the surface of the negative electrode active material (carbon powder), it can be appropriately removed.

Subsequently, it progresses to step TG and heat-processes a negative electrode active material (carbon powder) at the temperature of 600-3000 degreeC similarly to Example 2. FIG. Next, the process proceeds to step TH, and in the same manner as in Example 2 , the heat-treated negative electrode active material (carbon powder) is sieved, and the negative electrode active material (carbon powder) having an average particle diameter of 5 μm is recovered. The negative electrode active material (carbon powder) recovered in this way was equivalent to an unused (new) negative electrode active material (carbon powder). Therefore, the negative electrode active material (carbon powder) recovered by the recycling method of Example 3 can be reused as the negative electrode active material (carbon powder) of a newly manufactured battery.

( Reference Example 3 )
In Example 3 , in Step TD, as the organic solvent, a polar organic solvent having a solubility parameter (SP value) difference of less than 2.2 (MPa) ^1/2 with respect to PC which is a binder resin having polarity Was used. On the other hand, in Reference Example 3 , the difference in SP value from PC is less than 2.2 (MPa) ^{1/2 as} the organic solvent, but a nonpolar organic solvent is used. Specifically, benzene (SP value is 9.2 (cal / cm ³ ) ^1/2 = 18.8 (MPa) ^1/2 ) or the like can be used as the organic solvent.
Note that the recycling method of the present Reference Example 3 differs from the recycling method of Example 3 only in the process of Step TD, and the other processes are the same.

In Step TD of Reference Example 3 , PC (polycarbonate) which is a binder resin can be swollen by immersing the negative electrode active material layer in the organic solvent and heating. Thereby, the negative electrode active material (carbon powder) can be separated from the PC.

By the way, as described above, in Example 3 , when the negative electrode active material (carbon powder) taken out in Step TE was examined, almost no negative electrode active material having impurities attached to the surface thereof was found. However, in this reference example 3 , when the taken-out negative electrode active material (carbon powder) was investigated, many negative electrode active materials (carbon powder) had impurities adhering to the surface.

This is presumably because, in Example 3 , an organic solvent having polarity was used in the same manner as in Example 3 , but a nonpolar organic solvent was used in Reference Example 3 for PC which is a binder resin having polarity. According to the comparison between Example 3 and Reference Example 3 , even if the difference in SP value from the binder resin is less than 2.2 (MPa) ^1/2 , the solubility of PC varies greatly depending on the difference in polarity. I understand. That is, when a polar organic solvent is used, a negative electrode active material (carbon powder) free from impurities can be obtained by appropriately dissolving PC. On the other hand, when a nonpolar organic solvent is used, the PC cannot be dissolved and remains swollen, so that impurities tend to remain on the surface of the negative electrode active material (carbon powder). It was.

However, in Reference Example 3 , in Step TF, the impurities adhered to the surface of the negative electrode active material (carbon powder) by washing the negative electrode active material (carbon powder) with a polar organic solvent (such as ethanol). Can be removed appropriately. For this reason, the negative electrode active material (carbon powder) recovered by the recycling method of Reference Example 3 can also be reused as the negative electrode active material (carbon powder) of a newly produced battery.

In the above, the present invention has been described with reference to the first to third embodiments. However, the present invention is not limited to the above-described embodiments, and it can be applied as appropriate without departing from the scope of the present invention. Nor.
For example, in Embodiments 1 to 3 , the recycling method has been described for the batteries 100, 200, and 300 including the rectangular parallelepiped battery case 110 (hard case). However, the recycling method of the present invention can be used for a battery including any type of battery case. For example, for a battery including a battery case in which a laminate film obtained by bonding a metal film and a resin film is formed into a bag shape. In addition, the electrode base material, the active material, and the like can be appropriately recovered and reused.

In Examples 1 to 3 , a recycling method is described for batteries 100, 200, and 300 having flat wound bodies 150, 250, and 350 in which a positive electrode, a negative electrode, and a separator are wound as power generation elements. did. However, the recycling method of the present invention can be used for a battery having a power generation element of any structure such as a stacked power generation element in which a positive electrode, a negative electrode, and a separator are stacked.
In Examples 1 to 3 , the lithium ion secondary battery has been described as an object. However, the recycling method of the present invention includes an electrode base material and an active material layer (active material and binder resin fixed to the electrode base material). Any battery (primary battery and secondary battery) can be used.

It is a figure which shows the battery 100,200,300 used as the object of recycling of Examples 1-3 and Reference Examples 1-3 , (a) is a front view, (b) is a side view. It is a figure which shows sectional drawing of the battery 100,200,300, and is equivalent to AA sectional drawing of Fig.1 (a). 3 is a flowchart showing a flow of a battery recycling method according to Example 1 and Reference Example 1 . 6 is a graph comparing the case of hydrochloric acid treatment with the case of oxalic acid treatment in an electrode separation step (step S8). (A) is an X-ray diffraction pattern of an unused negative electrode active material (carbon), and (b) is an X-ray diffraction pattern of a negative electrode active material (carbon) recovered by using the recycling method of Example 1. 6 is a flowchart showing a flow of a battery recycling method according to Examples 2 and 3 and Reference Examples 2 and 3 ;

Explanation of symbols

100, 200, 300 Battery 110 Battery case 150 Flat wound body 155 Positive electrode 156 Negative electrode

Claims (3)

An electrode substrate;
An active material layer containing an active material and a binder resin, and an active material layer fixed to the electrode substrate,
A battery recycling method comprising:
The active material layer includes an aqueous binder resin as the binder resin,
The active material layer separated from the electrode base material is heated with an acidic aqueous solution to hydrolyze the aqueous binder resin, thereby separating the active material from the aqueous binder resin. And
The electrode substrate is made of copper,
Prior to the active material separation step, an electrode separation step of separating the electrode into the electrode base material and the active material layer by hydrochloric acid treatment,
The active material separation step includes
A battery recycling method including a heating step in which the active material layer separated in the electrode separation step is immersed in water and heated while hydrochloric acid is attached. An electrode substrate;
An active material layer containing an active material and a binder resin, and an active material layer fixed to the electrode substrate,
A battery recycling method comprising:
The active material layer includes a solvent-based binder resin as the binder resin,
The active material layer separated from the electrode substrate is heated together with an organic solvent, and the active material is separated from the solvent-based binder resin.
The active material separation step
As the organic solvent, an organic solvent in which the difference between the solubility parameter of the solvent and the solubility parameter of the solvent-based binder resin is less than 2.2 (MPa) ^1/2 ,
The active material layer includes a nonpolar solvent-based binder resin as the solvent-based binder resin,
The active material separation step includes
A battery recycling method using a nonpolar organic solvent as the organic solvent. An electrode substrate;
An active material layer containing an active material and a binder resin, and an active material layer fixed to the electrode substrate,
A battery recycling method comprising:
The active material layer includes a solvent-based binder resin as the binder resin,
The active material layer separated from the electrode substrate is heated together with an organic solvent, and the active material is separated from the solvent-based binder resin.
The active material separation step
As the organic solvent, an organic solvent in which the difference between the solubility parameter of the solvent and the solubility parameter of the solvent-based binder resin is less than 2.2 (MPa) ^1/2 ,
The active material layer includes a solvent-based binder resin having polarity as the solvent-based binder resin,
The active material separation step includes
A battery recycling method using an organic solvent having polarity as the organic solvent.

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