Recycling method and recycling device

Abstract

The present invention provides a recycling method and apparatus that can recover composite material from current collector foil without crushing the current collector foil beforehand. [Solution] A recycling method for peeling and recovering composite material from current collector foil used in lithium-ion batteries, comprising a superheated steam peeling step in which the current collector foil is peeled off the composite material from the current collector foil by hydrolysis or thermal decomposition of the active material auxiliary agent in an oxygen-free inert atmosphere using heated steam, and the peeled composite material is recovered.

Description

Technical Field

[0001] The present disclosure relates to a recycling method and a recycling apparatus.

Background Art

[0002] Patent Document 1 discloses a technique for a recycling method of a lithium-ion secondary battery in which a positive electrode made of an aluminum foil coated with an active material and a negative electrode made of a copper foil coated with an active material are laminated in a plurality of layers via a separator made of a plastic foil in a stainless steel container, and a non-aqueous electrolyte is injected and sealed. According to this technique, the lithium-ion secondary battery is put into a crusher having a rotating object and crushed, and the crushed product is separated and recovered into plastic, stainless steel, aluminum, copper, and an active material by a separating means.

[0003] Further, Patent Document 2 discloses a technique for a stabilization method of a lithium-ion secondary battery that is safely discharged. This stabilization method is to perform heat treatment between a temperature lower than both the decomposition temperature of the separator of the lithium-ion secondary battery and the SEI (Solid Electrolyte Interface) collapse temperature, and a temperature not lower than the gasification start temperature of the electrolyte of the lithium-ion secondary battery to deactivate the lithium-ion secondary battery.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the recovery method using a crusher with rotating parts, as described in Patent Document 1 above, when recovering black mass, which is a mixture of positive and negative electrodes, etc., from lithium-ion secondary batteries, the recovered mixture contains chain composition of iron fractions at a concentration of several hundred to several thousand ppm.

[0006] Furthermore, in the aforementioned Patent Document 1, in addition to iron, the aluminum of the positive electrode substrate and the copper of the negative electrode substrate are also crushed and pulverized, resulting in metal fragments ranging from several micrometers to several millimeters in size being mixed into the black mass, making physical separation difficult. In this case, conventional methods require chemical separation, such as acid washing, to remove the metal fragments. In particular, in direct recycling, where the active material is regenerated without returning it to active material materials such as sulfates, iron and copper are considered foreign matter, and there has been a need for a technology that can separate the black mass from the current collector foil, such as aluminum, without the inclusion of fine metal fragments.

[0007] This disclosure has been made in view of the above, and aims to provide a recycling method and a recycling apparatus that can recover composite material from current collector foil without crushing the current collector foil beforehand. [Means for solving the problem]

[0008] To solve the above-mentioned problems and achieve the objectives, the recycling method relating to this disclosure is a recycling method for peeling and recovering composite material from current collector foil used in lithium-ion batteries, and includes a superheated steam peeling step in which the current collector foil is peeled off the composite material from the current collector foil by hydrolysis or thermal decomposition of the active material auxiliary agent in an oxygen-free inert atmosphere using heated steam, and the peeled composite material is recovered.

[0009] Furthermore, the recycling apparatus according to this disclosure comprises a furnace having a mesh section with a predetermined mesh size on which current collector foil used in lithium-ion batteries can be placed, a heating gas device capable of supplying heated inert gas into the furnace, a superheated steam device capable of supplying superheated steam into the furnace, and a control device that controls the heating gas device and the superheated steam device, respectively. [Effects of the Invention]

[0010] According to this disclosure, the composite material can be recovered from the current collector foil without having to crush the electrodes beforehand. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a diagram showing the schematic configuration of a recycling device according to one embodiment. [Figure 2] Figure 2 is a flowchart illustrating an overview of a separation method for separating the current collector foil of a lithium-ion secondary battery using a dry method according to one embodiment. [Figure 3] Figure 3 is a flowchart showing a detailed overview of the superheated steam process according to one embodiment. [Figure 4] Figure 4 shows the relationship between the temperature of the furnace 10 in the recycling apparatus 1 and time in a superheated steam process according to one embodiment. [Figure 5] Figure 5 is a schematic diagram showing the state inside the furnace during an inert gas heating process according to one embodiment. [Figure 6] Figure 6 is a schematic diagram showing the state inside the furnace during a superheated steam treatment process according to one embodiment. [Modes for carrying out the invention]

[0012] The following description will explain the recycling apparatus and recycling method according to embodiments of the present disclosure with reference to the drawings. Note that the components in the following embodiments include those that are easily substituted or substantially identical to those that are easily substituted by those skilled in the art. Furthermore, the figures referenced in the following description only schematically show the shape, size, and positional relationships to the extent that the contents of the present disclosure can be understood. In other words, the present disclosure is not limited to the shapes, sizes, and positional relationships exemplified in the figures.

[0013] [Recycling equipment] FIG. 1 is a diagram showing a schematic configuration of a recycling apparatus according to an embodiment. The recycling apparatus 1 shown in FIG. 1 performs direct recycling that regenerates a current collector foil (positive electrode or negative electrode) used in a lithium-ion secondary battery without returning it to the raw material, and can dry-strip a composite material from an electrode such as a current collector foil and recover the composite material.

[0014] The recycling apparatus 1 shown in FIG. 1 includes a furnace 10 (treatment tank), a gas supply device 20 that supplies a heating gas without water vapor into the furnace 10, a superheated steam device 30 that supplies superheated steam to the furnace 10, a supply path 40 that connects the gas supply device 20 and the superheated steam device 30 to the furnace 10, a switching valve 50 that switches the supply path of the heating gas or superheated steam, an exhaust path 60 for the gas exhausted from the furnace 10, and a control device 70.

[0015] The furnace 10 includes a mesh portion 11 on which a workpiece W1 such as a current collector foil can be placed, a supply port 12 to which the supply path of the gas supply device 20 or the superheated steam device 30 is connected, an exhaust port 13 that exhausts the gas (waste gas, pyrolysis gas, etc.) generated in the furnace 10 to the exhaust path, and a temperature sensor 14 that detects the temperature inside the furnace 10 and outputs it to the control device 70. The mesh portion 11 is configured with a predetermined mesh size and is provided above the supply port 12 that supplies a heating gas without water vapor or superheated steam. Here, the predetermined mesh size is about 20 mm in the vertical direction.

[0016] The gas supply device 20 supplies a heating gas without water vapor to the furnace 10 via the supply path 40 under the control of the control device 70.

[0017] The superheated steam device 30 supplies superheated steam to the furnace 10 via the supply path 40 under the control of the control device 70. The superheated steam device 30 is configured using a boiler or the like and supplies pure water superheated by the boiler. The boiler may be configured using an IH, an electric heater, or the like. Further, the superheated steam device 30 superheats pure water and supplies superheated steam of 500 °C or higher to the furnace 10.

[0018] The supply path 40 is connected to the gas supply device 20 and the superheated steam device 30 and is also connected to the furnace 10.

[0019] The switching valve 50 switches the connection destination of the supply passage 40 to the gas supply device 20 or the superheated steam device 30 under the control of the control device 70.

[0020] The exhaust passage 60 exhausts the gas from the furnace 10 to the outside. In one embodiment, a heat exchanger may be provided on the path of the exhaust passage 60, and heat exchange may be performed between the gas before heating and the heat exchanger. Thereby, the furnace 10 can achieve an energy cost equivalent to that of a normal electric furnace.

[0021] The control device 70 is realized by a processor composed of a CPU (Central Processing Unit) or the like, a memory (main storage unit) composed of a RAM (Random Access Memory), a ROM (Read Only Memory), etc., and an input interface such as a keyboard and a mouse. The control device 70 controls the gas supply device 20, the superheated steam device 30, and the switching valve 50. Specifically, the control device 70 controls the gas supply device 20, the superheated steam device 30, and the switching valve 50 based on the detection result detected by the temperature sensor 14.

[0022] 〔Method for Separating the Current Collector Foil of a Lithium-Ion Secondary Battery Dry〕 Next, an outline of the method for separating the current collector foil of a lithium-ion secondary battery dry will be described. FIG. 2 is a flowchart showing an outline of the method for separating the current collector foil of a lithium-ion secondary battery dry. In the following, the method for separating the positive electrode of the current collector foil as the work W1 dry will be described, but it can also be applied to the negative electrode.

[0023] As shown in FIG. 2, first, the operator performs a discharge and detoxification process step (step S1) on the lithium-ion secondary battery pack to discharge it and make it safely handleable, and disassembles the lithium-ion secondary battery pack to perform a pack disassembly process step (step S2) of separating the battery stack or battery module from the constituent members.

[0024] Next, the worker performs a stack / module dismantling process (step S3) in which the battery stack or battery module is released from its restraints and dismantled into individual battery cells, and then performs an electrolyte recovery process (step S4) in which the sealed battery cells are opened and the electrolyte filling the spaces between the electrodes is recovered by superheating, reduced pressure drying, etc.

[0025] Subsequently, the worker performs a cell dismantling process (step S5) in which the battery cell is separated into the can case, terminals, resin components, positive electrode, negative electrode, and separator.

[0026] Next, the operator loads the workpiece into the recycling device 1, heats the workpiece using batch heating, switches to superheated steam, and then performs a superheated steam process (step S6) in which the auxiliary agent is decomposed by heat treatment and hydrolysis reaction of the steam, and the positive electrode composite material and aluminum substrate are recovered, thus completing this method. Details of the superheated steam process will be described later.

[0027] [Details of the superheated steam process] Next, the superheated steam process described in step S6 of Figure 2 will be explained in detail. Figure 3 is a flowchart showing a detailed overview of the superheated steam process. Figure 4 is a diagram showing the relationship between the temperature of the furnace 10 in the recycling device 1 and time during the superheated steam process. In Figure 4, the horizontal axis represents time, and the vertical axis represents temperature. Also in Figure 4, the broken line L1 shows the change in the temperature of the furnace 10 over time during the superheated steam process.

[0028] As shown in Figure 3, the control device 70 controls the gas supply device 20 and the switching valve 50 based on the operation information provided by the operator to the input interface, and performs an inert gas heating process in which water vapor-free heated gas is supplied to the furnace 10 (step S61).

[0029] Figure 5 is a schematic diagram showing the state inside the furnace 10 during the inert gas heating process. As shown by the broken line L1 in Figures 5 and 4, the control device 70 raises the temperature inside the furnace 10 using the heating gas supplied by the gas supply device 20. In this case, the control device 70 controls the gas supply device 20 to preheat the furnace 10 with the heating gas. This prevents condensation from forming on the workpiece W1, such as the positive electrode, and the furnace 10. As a result, deterioration of the positive electrode active material of the workpiece W1 can be prevented.

[0030] Next, based on the detection result of the temperature sensor 14, the control device 70 controls the superheated steam device 30 and the switching valve 50 when a predetermined temperature is reached, and performs a superheated steam treatment process to supply superheated steam to the furnace 10 (step S62).

[0031] Figure 6 is a schematic diagram showing the state inside the furnace 10 during the superheated steam treatment process. As shown by the broken line L1 in Figures 6 and 4, the control device 70 applies heat treatment to the workpiece W1 with superheated steam to promote hydrolysis, thereby separating the asphalt mixture from the aluminum substrate W2 of the workpiece W1. As a result, the separated asphalt mixture W3 falls through the mesh section 11. At this time, based on the detection result of the temperature sensor 14, the control device 70 superheats pure water in the superheated steam device 30 and supplies superheated steam so that the temperature inside the furnace 10 reaches 500°C or higher. As a result, inside the furnace 10, the workpiece W1 is hydrolyzed or thermally decomposed by superheated steam in an oxygen-free inert atmosphere, causing the active material additives to be removed from the aluminum substrate W2. Furthermore, even if the workpiece W1 contains flammable components such as electrolyte, combustion that consumes oxygen does not occur in the superheated steam atmosphere, and the asphalt mixture can be safely removed from the aluminum substrate W2 through a chemically stable decomposition and carbonization reaction. Furthermore, because the superheated steam supplied by the superheated steam device 30 has a high thermal density, the airflow can be reduced, and compared to normal airflow drying, the asphalt material W3 that is blown up by the airflow naturally falls to the bottom of the mesh section 11.

[0032] Subsequently, the control device 70 performs a recovery process (step S63) in which it stops the supply of superheated steam from the superheated steam device 30 after a predetermined time has elapsed. In this case, the worker recovers the asphalt detachment W3 that has fallen below the mesh section 11. Furthermore, if there is asphalt detachment W3 resting on the aluminum substrate W2 (aluminum foil), the worker lightly taps or shakes the aluminum substrate W2 to cause the asphalt detachment W3 on the aluminum substrate W2 to fall to the bottom of the mesh section 11 and recover it. After step S63, the method is terminated.

[0033] According to the embodiment described above, the asphalt mixture detached W3 can be recovered by processing at 500°C or higher in a non-oxygen atmosphere and dry process, where combustion by oxygen does not occur, and by decomposition and carbonization of the auxiliary agent by steam reforming, thereby separating the asphalt mixture from the positive electrode workpiece W1. As a result, only the asphalt mixture from the positive electrode can be recovered without the need to crush the electrode beforehand. Similarly, only the asphalt mixture from the negative electrode can be recovered.

[0034] Furthermore, according to one embodiment, by using superheated steam at 500°C or higher to increase its thermal conductivity compared to air, the asphalt mixture can be peeled off and recovered even from a coiled workpiece W1 that has not been crushed.

[0035] Furthermore, according to one embodiment, when the workpiece W1 is the positive electrode, it is possible to recover olivine (LFP) active material composites that cannot undergo oxidation treatment that significantly alters the crystal structure in direct recycling. In addition, even in layered systems (NCM), if deficient lithium is added after steam delamination and then treated in an oxidizing atmosphere, recycling is possible without changing the crystal structure, and a highly versatile treatment can be performed regardless of the type of active material.

[0036] Furthermore, according to one embodiment, when the workpiece W1 is the anode, the graphite structure is less susceptible to the steam reforming reaction, allowing it to be processed at a higher temperature range of 650°C or above than the cathode. This makes it possible to remove CMC and SBR additives and recover a composite material with a high graphite ratio that is also useful for direct recycling of the anode. In other words, if it is the anode, a negative electrode composite material with an increased graphite composition of the anode active material and a copper substrate can be recovered.

[0037] Further effects and modifications can be readily derived by those skilled in the art. Broader aspects of the present invention are not limited to the specific details and representative embodiments expressed and described above. Accordingly, various modifications are possible without departing from the spirit or scope of the overall concept of the invention as defined by the appended claims and their equivalents.

[0038] Although some embodiments of this application have been described in detail above with reference to the drawings, these are illustrative examples, and the present invention can be implemented in various other forms with modifications and improvements based on the knowledge of those skilled in the art, starting with the embodiments described in the disclosure section of the present invention. [Explanation of Symbols]

[0039] 1. Recycling device 10 furnace 11 Mesh section 12 supply ports 13 Exhaust vent 14. Temperature sensor 20 Gas supply equipment 30 Superheated steam equipment 40 Supply route 50 Switching valve 60 Exhaust passage 70 Control device W1 Work W2 Aluminum Substrate W3 Asphalt mixture strip

Claims

1. A recycling method for peeling and recovering composite material from current collector foil used in lithium-ion batteries, The process includes a superheated steam peeling step in which the current collector foil is peeled off by hydrolyzing or thermally decomposing the active material additive in an oxygen-free inert atmosphere using heated steam, thereby peeling the composite material from the current collector foil, and recovering the peeled composite material. Recycling methods.

2. A recycling method according to claim 1, The superheated steam peeling process is, An inert gas heating step is performed by supplying an inert gas to the current collector foil, which is placed on a mesh section of a predetermined mesh size provided inside the furnace, and heating it. A superheated steam step, which supplies superheated steam into the furnace, A recovery step for recovering the asphalt material that has fallen from the mesh section, including, Recycling methods.

3. A recycling method according to claim 2, The superheated steam process described above is: The superheated steam at 500°C or higher is supplied. Recycling methods.

4. A recycling method according to claim 3, The aforementioned mesh size is, It makes up 20 mm, Recycling methods.

5. A furnace having a mesh section inside which a current collector foil used in lithium-ion batteries can be placed, which is configured with a predetermined mesh size, A heating gas device capable of supplying heated inert gas into the furnace, A superheated steam device capable of supplying superheated steam into the furnace, A control device that controls each of the aforementioned heating gas device and the aforementioned superheated steam device, Equipped with, Recycling device.

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