Battery processing method and battery processing system

Abstract

To provide a battery processing method and battery processing system that can efficiently recover lithium from lithium-ion batteries. [Solution] The present invention provides a battery processing method for processing a lithium-ion battery comprising a positive electrode material and a negative electrode material, wherein the positive electrode material and the negative electrode material are stacked in a stacking direction, the method comprising: a structural change step of charging and discharging the lithium-ion battery to cause a structural change on the surface of the negative electrode active material; and a lithium deposition step of charging and discharging the lithium-ion battery to deposit lithium on the negative electrode material.

Description

Technical Field

[0001] The present invention relates to a battery processing method and a battery processing system.

Background Art

[0002] In recent years, the adoption of lithium-ion batteries as in-vehicle batteries for electric vehicles such as electric vehicles and hybrid vehicles has been expanding. Lithium-ion batteries contain valuable substances containing lithium. It is required to recycle resources by recycling valuable substances from used lithium-ion batteries.

[0003] Patent Document 1 discloses a method of increasing the amount of lithium contained in a positive electrode material by discharging a used lithium-ion battery and then recovering lithium from the positive electrode material.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The positive electrode material is generally composed of forming a positive electrode active material on a current collector foil such as aluminum. The positive electrode active material contains valuable substances such as nickel, manganese, and cobalt, for example, in the case of a ternary system (NMC). To recover valuable substances from the positive electrode active material, the positive electrode material is baked with a reducing agent, pulverized, and then a black mass containing the positive electrode active material is sorted. Next, the black mass is subjected to solvent extraction step by step, whereby manganese, cobalt, and nickel are sequentially extracted, and finally lithium is extracted. For this reason, it has been particularly troublesome to recover lithium.

[0006] The object of this invention is to provide a battery processing method and a battery processing system that can efficiently recover lithium from lithium-ion batteries.

[0007] One aspect of the present invention is, A battery processing method for processing a lithium-ion battery comprising a positive electrode material and a negative electrode material, wherein the positive electrode material and the negative electrode material are stacked in a stacking direction, A structural change step is performed in which the lithium-ion battery is charged and discharged to cause a structural change on the surface of the negative electrode active material, A lithium deposition process is performed by charging and discharging the lithium-ion battery to deposit lithium on the negative electrode material. Includes.

[0008] Other aspects of the present invention include: A battery processing system for processing lithium-ion batteries, which include a positive electrode material and a negative electrode material, A pressing device for pressing at least a portion of the lithium-ion battery and A charge / discharge device for charging and discharging the aforementioned lithium-ion battery, It is equipped with. [Effects of the Invention]

[0009] According to the present invention, lithium can be efficiently recovered from the negative electrode of a lithium-ion battery. [Brief explanation of the drawing]

[0010] [Figure 1] A schematic block diagram illustrating the reuse system according to the first embodiment. [Figure 2] A perspective view showing the schematic configuration of a lithium-ion battery. [Figure 3] A cross-sectional view showing the general configuration of a battery cell. [Figure 4] A flowchart illustrating the general process of reusing lithium-ion batteries. [Figure 5] A graph showing the relationship between the charge rate relative to the State of Charge (SOC) and the ease of lithium deposition at different cooling temperatures. [Figure 6]A diagram schematically showing pulse charging. [Figure 7] A block diagram schematically showing a reuse system according to the third embodiment. [Figure 8] A diagram showing a schematic configuration of a pressing device. [Figure 9] A flowchart schematically showing the flow of reuse according to the fourth embodiment. [Figure 10A] A diagram schematically showing an example of the operation of a pressing device. [Figure 10B] A diagram schematically showing an example of the operation of the pressing device following FIG. 8A. [Figure 11A] A diagram schematically showing another example of the operation of a pressing device. [Figure 11B] A diagram schematically showing another example of the operation of the pressing device following FIG. 9A. [Figure 11C] A diagram schematically showing another example of the operation of the pressing device following FIG. 9B.

Embodiments for Carrying Out the Invention

[0011] The inventors of the present invention have conducted intensive research to efficiently recover lithium from a lithium-ion battery, and have found that lithium precipitation (for example, dendrite), which is not desirable in a normal charging reaction, can be intentionally caused on the negative electrode material to efficiently recover lithium from the lithium-ion battery. Based on this finding, the inventors of the present invention have completed a battery treatment method capable of efficiently recovering lithium from a lithium-ion battery.

[0012] A method for reusing a lithium-ion battery according to an embodiment of the present invention is a battery treatment method for treating a lithium-ion battery including a positive electrode material and a negative electrode material, wherein the positive electrode material and the negative electrode material are laminated in a stacking direction, and includes a lithium precipitation step of charging the lithium-ion battery to precipitate lithium on the negative electrode material, a battery disassembly step of disassembling at least the negative electrode material from the lithium-ion battery, and a lithium extraction step of extracting lithium from the negative electrode material and includes.

[0013] [First Embodiment] Hereinafter, a lithium-ion battery reuse system according to a first embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a block diagram schematically showing a reuse system 100 for a lithium-ion battery 1. As shown in FIG. 1, the reuse system 100 includes a reuse unit 10 that reuses the lithium-ion battery 1 that has been used once, for example, in an electric vehicle, and a recycling unit 20 that recovers lithium from the reused lithium-ion battery 1.

[0014] The reuse unit 10 reuses the once-used lithium-ion battery 1 as a power storage device. Generally, the state of deterioration of a lithium-ion battery for an electric vehicle is determined based on SOH (State Of Health), which indicates how much capacity there is when fully charged compared to, for example, when it is new. When the lithium-ion battery 1 is determined to be inappropriate for use in an electric vehicle based on the degree of deterioration, it is removed from the vehicle and used in the reuse unit 10 as a power storage device for various secondary uses such as storing renewable energy such as solar power generation and wind power generation, or as a backup power source during disasters. For example, when the SOH becomes 70% or less, it may be determined that it is not appropriate for primary use, that is, for use in an electric vehicle.

[0015] The reuse unit 10 includes a lithium-ion battery 1 reused as a power storage device and a charging device 12. The charging device 12 is configured to adjust the voltage and current so that the lithium-ion battery 1 can be charged in an arbitrary charging pattern. For example, the lithium-ion battery 1 can be continuously charged at a predetermined voltage and current, and can also be intermittently charged at a predetermined voltage and current (also referred to as pulse charging). The upper limit of the charging voltage by the charging device 12 is below the withstand voltage of the lithium-ion battery 1, for example, 4.3V or less.

[0016] The reuse unit 10 further includes a cooling device 201 capable of cooling the lithium-ion battery 1. The cooling device 201 is not limited to any type of cooling device. In this embodiment, a constant temperature bath is used as the cooling device 201. For example, the cooling device 201 may be configured as a cooling chamber whose interior can be cooled, and the lithium-ion battery 1 may be cooled by housing the lithium-ion battery 1 in the cooling chamber.

[0017] The recycling unit 20 includes a dismantling device 21 that dismantles the lithium-ion battery 1 into positive electrode material 31 and negative electrode material 35, etc., through a lithium deposition process described later, if it is determined that the lithium-ion battery 1 cannot be properly reused even in the above secondary reuse, for example, based on SOH; an extraction device 22 that extracts lithium from the dismantled negative electrode material 35; and a recovery device 23 that recovers the extracted lithium. For example, it may be determined that the battery cannot be properly reused even in secondary reuse if the SOH is 40% or less.

[0018] Figure 2 schematically shows a lithium-ion battery 1 installed in an electric vehicle. The lithium-ion battery 1 is a battery pack in which multiple battery modules 4, each incorporating functions such as a charge / discharge circuit and a cooling mechanism, are connected to each other and housed in a case. The battery module 4 is composed of multiple battery cells 3 connected to each other in series or parallel, and is adjusted to the desired capacity and voltage.

[0019] Lithium-ion battery 1 is a rechargeable lithium-ion secondary battery. In this specification, unless otherwise specified, the term lithium-ion battery may collectively refer to battery cells, battery modules, and battery packs.

[0020] Figure 3 is a schematic cross-sectional view of the battery cell 3. As shown in Figure 3, the battery cell 3 according to this embodiment is of the laminated type (stacked type). The battery cell 3 has a stacked electrode body 38 in which a positive electrode material 31, a separator 34, and a negative electrode material 35 are stacked in this order in the stacking direction A, and a case 40 in which the stacked electrode body 38 is housed.

[0021] In this embodiment, the laminated electrode body 38 is constructed by stacking multiple sets of positive electrode material 31, separator 34, and negative electrode material 35 in the stacking direction A. The laminated electrode body 38 has a positive electrode current collection end 32a at one end (left side in Figure 3) in the width direction B (left-right direction in Figure 3) perpendicular to the stacking direction A, to which multiple positive electrode current collectors 32 are connected, and a negative electrode current collection end 36a at the other end (right side in Figure 3) to which multiple negative electrode current collectors 36 are connected. The battery cell 3 is elongated rectangular in the width direction B when viewed from the stacking direction A.

[0022] The positive electrode material 31 comprises a positive electrode current collector 32 and a positive electrode active material 33 laminated on the surface of the positive electrode current collector 32 facing the separator 34. Multiple positive electrode current collectors 32 have positive electrode current collector ends 32a connected to each other at one end (left side in Figure 3) in the width direction B perpendicular to the lamination direction. Suitable metal foils for positive electrodes can be preferably used for the positive electrode current collector 32. Materials used as positive electrode active materials for lithium-ion secondary batteries can be used for the positive electrode active material 33. In this embodiment, the positive electrode current collector 32 is made of aluminum, and the positive electrode active material 33 is made of NMC (nickel, manganese, cobalt).

[0023] The negative electrode material 35 comprises a negative electrode current collector 36 and a negative electrode active material 37 laminated on the surface of the negative electrode current collector 36 facing the separator 34. Multiple negative electrode current collectors 36 have negative electrode current collector ends 36a connected to each other at their other ends (right side in Figure 3) in the width direction B. A metal foil suitable for a negative electrode can preferably be used for the negative electrode current collector 36. A material used as a negative electrode active material for lithium-ion secondary batteries can be used for the negative electrode active material 37. In this embodiment, the negative electrode current collector 36 is made of copper, and the negative electrode active material 37 is a carbon material (graphite) with a layered structure.

[0024] The positive electrode active material 33 and the negative electrode active material 37 contain an electrolyte 39. The electrolyte 39 is, for example, an organic solvent on which lithium ions can move. In this embodiment, the electrolyte 39 contains dimethyl carbonate (DMC), ethylene carbonate (EC), and diethyl carbonate (DEC) in a volume ratio of 1:1:1, and contains lithium hexafluoride phosphate (LiPF6) at a concentration of 1 mol / L.

[0025] The separator 34 is positioned between the positive electrode material 31 and the negative electrode material 35, physically and electrically separating them. The separator 34 may be a porous material having multiple minute pores through which lithium ions can pass. In this embodiment, the separator 34 is a porous membrane made of polyolefin.

[0026] Case 40 has a pair of first cases 41 and second cases 42 provided on both sides of the stacking direction A of the stacked electrode body 38. The first case 41 and the second case 42 are formed in a hat-shaped cross section. The first case 41 has a pair of flange portions 41a located at both ends in the width direction B, and a main body portion 41b located between the pair of flange portions 41a and bulging in a direction away from the second case 42 in the stacking direction A. Similarly, the second case 42 has a pair of flange portions 42a and a main body portion 42b bulging in a direction away from the first case 41.

[0027] Case 40 is formed by joining a first case 41 and a second case 42 with the positive electrode current collector end 32a and the negative electrode current collector end 36a sandwiched between their respective flange portions 41a and 42a. That is, with the laminated electrode body 38 housed in case 40, the positive electrode current collector end 32a and the negative electrode current collector end 36a are sandwiched between the pair of flange portions 41a and 42a, and the remaining portion of the laminated electrode body 38 is housed in the space defined between the pair of main body portions 41b and 42b. With the laminated electrode body 38 housed in case 40, it is pressed against the pair of main body portions 41b and 42b at a predetermined pressure in the stacking direction A. An example of the tab 43 according to the present invention is formed by the portion of the battery cell 3 sandwiched between the pair of flange portions 41a and 42a.

[0028] Next, the reuse of the lithium-ion battery 1 will be explained. Figure 4 is a flowchart that schematically shows the reuse process of the lithium-ion battery 1. As shown in Figure 4, if the lithium-ion battery 1 that was installed in the electric vehicle is determined to be in a deteriorated state that is unsuitable for use in the electric vehicle, for example based on the State of Health (SOH), a reuse process (step S1) is carried out. In reuse process S1, the lithium-ion battery 1 is removed from the electric vehicle and put to secondary use in the reuse unit 10.

[0029] When the lithium-ion battery 1 is used for secondary purposes and is determined to be in a predetermined state of degradation after being used as an energy storage device, a structural change process (step S2) is performed in the reuse section 10 following the secondary use. In the structural change process S2, the lithium-ion battery 1 is charged and discharged in such a way that a structural change occurs on the surface of the negative electrode active material.

[0030] In the structural change step S2, the surface structure of the negative electrode active material can be changed by applying a current exceeding the rated current. The current may be, for example, 1.1 times or more, 1.5 times or more, or 2 times or more of the rated current. A change in the surface structure of the negative electrode active material may, for example, if the material of the negative electrode active material is graphite, result in the destruction of the layer structure or honeycomb structure of the surface layer of the graphite. A change in the surface structure of the negative electrode active material can be detected, for example, by observing the change in shape of the active material particle surface from the electrode surface using a scanning electron microscope (SEM) or transmission electron microscope (TEM), or by observing the change in shape and structure of the active material particle surface from the cross-section of the electrode using a focused ion beam processing-scanning electron microscope (FIB-SEM) or transmission electron microscope (TEM). Furthermore, if the negative electrode active material is graphite, it can be detected by analyzing the chemical state changes of the carbon atoms constituting the graphite using Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), or X-ray absorption spectroscopy (XAS, XAFS), or by analyzing the changes in the crystal structure of the graphite using X-ray diffraction (XRD) or electron diffraction.

[0031] In the structural change process S2, pulse charging, which is performed intermittently, is preferably employed as the charging method. Specifically, the pulse charging in the structural change process S2 includes a charging phase in which charging is performed so as to cause a structural change on the surface of the negative electrode active material, and a discharge phase, and these are repeated multiple times.

[0032] A lithium deposition process (step S3) is performed. In the lithium deposition process S3, lithium is deposited on the negative electrode material 35. In the lithium deposition process S3, the lithium-ion battery 1 is charged in such a way that lithium is deposited on the negative electrode material 35. As the structure of the surface of the negative electrode active material has changed due to the structural change process S2, lithium is preferentially deposited on the parts where the structure has changed. This makes subsequent lithium recovery easier.

[0033] In the lithium deposition process S3, the lithium-ion battery 1 is preferably charged while being cooled by a cooling device 201 under predetermined cooling conditions. Here, the graph in Figure 5 shows the relationship between the charge rate (charging current) at which lithium begins to deposit and the State of Charge (SOC) for each temperature. Specifically, lithium is more likely to deposit on the negative electrode material 35 when charging is performed in the region on and above the curves for each temperature. SOC is an index that indicates the charge state of the battery, and represents the battery capacity when the fully charged state is 100% and the completely discharged state is 0%. As shown in Figure 6, lithium is more likely to deposit in the lithium-ion battery 1 as the SOC increases and / or as the temperature decreases.

[0034] Therefore, in the lithium deposition step S3, the lithium-ion battery 1 is charged at a charge rate that causes lithium to deposit on the negative electrode material 35 relative to the cooling temperature. Preferably, the lithium-ion battery 1 is charged under charging conditions that cause lithium to begin to deposit on the negative electrode material 35. For example, by cooling the lithium-ion battery 1, lithium can be deposited on the negative electrode material 35 even if the charge rate is kept low.

[0035] In the lithium deposition process S3, pulse charging, which is performed intermittently, is preferably employed as the charging method. Specifically, as shown in Figure 6, pulse charging includes a charging phase Fc in which lithium is deposited and a charging pause phase Fs in which the charging is stopped, and these are repeated multiple times. At least the charging phase Fc is performed multiple times. Cooling by the cooling device 201 is performed only during the charging phase Fc and not during the charging pause phase Fs.

[0036] Here, as lithium is deposited on the negative electrode material 35, the amount of lithium ions present in the vicinity of the negative electrode active material 37 (at least in the region adjacent to the negative electrode active material) decreases. As a result, the lithium ion concentration decreases in the vicinity of the negative electrode active material 37, making it difficult to effectively deposit lithium on the negative electrode material 35 even if charging continues. Therefore, according to this embodiment, during the pause phase Fs of pulse charging, lithium ions around the negative electrode active material 37 tend to gather in the vicinity of the negative electrode active material 37, and the decrease in lithium ion concentration in the vicinity of the negative electrode active material 37 can be mitigated. Thus, by performing the charging phase Fc after the decrease in lithium ion concentration has been mitigated, lithium can be effectively deposited on the negative electrode material 35.

[0037] Next, the lithium-ion battery 1 is removed from the reuse section 10 and the battery dismantling process (step S4) is performed by the dismantling device 21. In the battery dismantling process S4, the lithium-ion battery 1 is dismantled into its constituent components, such as the positive electrode material 31, separator 34, negative electrode material 35, and case 40. If the intention is to recover only lithium, at least the negative electrode material 35 may be dismantled. The dismantling device 21 may be any device that automatically dismantles the lithium-ion battery 1. Alternatively, the lithium-ion battery 1 may be dismantled manually using tools or the like without using the dismantling device 21.

[0038] Next, a lithium extraction process (step S5) is carried out. In lithium extraction process S5, lithium is extracted from the disassembled negative electrode material 35. In lithium extraction process S5, the negative electrode current collector 36 and negative electrode active material 37 are removed from the negative electrode material 35 by the extraction device 22, which then filters the negative electrode material 35 after it has been leached with water, thereby extracting an aqueous solution containing lithium ions.

[0039] Finally, a lithium recovery process (step S5) is carried out. In lithium recovery process S5, lithium is recovered from an aqueous solution containing lithium ions. In lithium recovery process S5, the lithium is dissolved in carbonated water by the recovery device 23 and then filtered to recover lithium as lithium carbonate.

[0040] In other words, the battery processing method according to this embodiment is A battery processing method for processing a lithium-ion battery containing a positive electrode material and a negative electrode material, A structural change step is performed in which the lithium-ion battery is charged and discharged to cause a structural change on the surface of the negative electrode active material, A lithium deposition process is performed by charging and discharging the lithium-ion battery to deposit lithium on the negative electrode material. Includes.

[0041] Furthermore, the reuse system (battery processing system) 100 according to this embodiment is A battery processing system for processing lithium-ion batteries, which include a positive electrode material and a negative electrode material, A pressing device for pressing at least a portion of the lithium-ion battery and A charge / discharge device for charging and discharging the aforementioned lithium-ion battery, It is equipped with.

[0042] In the above embodiment, the type of lithium-ion battery 1 is not particularly limited, but preferably, the lithium-ion battery 1 is a capacity type (also called an energy type) rather than a high-power type (also called a power type). In a capacity type lithium-ion battery, the density of the negative electrode active material 37 is higher than in a high-power type lithium-ion battery. Therefore, it becomes difficult to extract lithium deposited in the negative electrode active material 37, for example, between the layers of graphite. In the method of this disclosure, a structural change is caused on the surface of the negative electrode active material, and lithium is selectively deposited there, thereby reducing the deposition of lithium between the layers of graphite. This improves the lithium recovery efficiency. In other words, the effects of the present invention are more favorably exhibited when the lithium-ion battery 1 is a capacity type.

[0043] Herein, in this specification, a lithium-ion battery 1 is considered high-power type if its power density is 4000 kW / L or higher. On the other hand, a lithium-ion battery 1 is considered capacity type if its energy density is 600 Wh / L or higher.

[0044] In the above embodiment, the case in which the lithium-ion battery 1 is provided in the form of a battery pack in the reuse process S1 and then the structural change process S2 is carried out was described as an example, but the embodiment is not limited to this. The lithium-ion battery 1 may be provided in the form of a battery module 4 or a battery cell 3 in the reuse process S1 and / or the structural change process S2.

[0045] [Second Embodiment] The second embodiment differs in that a second structural change step S12 (see Figure 4) is used instead of the structural change step S2 according to the first embodiment. In the second structural change step S12, based on the structural change step S2, the lithium-ion battery 1 is further pressed in the stacking direction A under predetermined pressing conditions during charging.

[0046] Figure 7 is a schematic block diagram showing the reuse system 300 according to the second embodiment. As shown in Figure 7, the reuse system 300 differs from the reuse system 100 according to the first embodiment in that the lithium-ion battery 1 is provided to the reuse section 10 in the form of battery cells 3, and the reuse section 10 is equipped with a pressing device 301 that presses the battery cells 3 in the stacking direction A.

[0047] The pressing device 301 is a device that presses the battery cells 3 in the stacking direction A with a predetermined pressing force. The pressing device 301 may be installed in the lithium-ion battery 1 that has been primarily used in an electric vehicle in order to generate a charge-discharge reaction within the lithium-ion battery 1, or it may be installed in the lithium-ion battery 1 that has been secondarily used in the reuse section 10. Alternatively, a separate pressing device that can adjust the pressing force automatically or manually may be provided.

[0048] Figure 8 is a schematic diagram of the pressing device 301. Figure 8 also schematically shows the battery cell 3 that is pressed by the pressing device 301. As shown in Figure 8, the pressing device 301 has a pair of presser pairs 302 provided on both sides of the stacking direction A of the battery cell 3, and divided in the width direction B of the battery cell 3. In this embodiment, there is a central presser pair 302A located in the center of the width direction B, a side presser pair 302B located on one side of the width direction B (left side in Figure 8), and a other side presser pair 302C located on the other side of the width direction B (right side in Figure 8). The presser pairs 302 are not limited to three, but may be divided into two or four or more.

[0049] In the second structural change step S12, the battery cell 3 is charged while being locally pressed by activating at least some of the presser pairs 302 of the multiple presser pairs 302. Therefore, in the second structural change step S12, the battery cell 3 is charged by increasing the pressing force in the stacking direction A in at least a portion of it compared to the remaining portion. In the second structural change step S12, the battery cell 3 is pressed with a pressing force such that a structural change occurs on the surface of the negative electrode active material due to the charge-discharge reaction. For example, the pressing force is 10 kPa or more and 1 MPa or less.

[0050] As a result, when charging the lithium-ion battery 1, increasing the pressing force in at least a portion of the battery can promote a structural change on the surface of the negative electrode active material in the negative electrode material 35 corresponding to that portion. This makes it easier to deposit lithium locally in the subsequent lithium deposition process. For example, lithium may be deposited over the entire surface of the negative electrode material 35 by sequentially changing the location where the pressing force is increased during charging. Alternatively, lithium may be efficiently deposited in areas where electrolyte remains by increasing the pressing force in those areas.

[0051] "Increasing the pressing force in the stacking direction A in at least a portion compared to the remaining portion" also means reducing the pressing force in the remaining portion when the entire battery cell 3 is being pressed evenly. For example, in a lithium-ion battery 1 that is being reused in the reuse section 10, i.e., is being pressed evenly throughout, partially reducing or releasing the pressing force is included in the second structural change step S12. In this way, when the second structural change step S12 is carried out using the pressing device provided in the lithium-ion battery 1 that has been reused, it is possible to carry out the work efficiently without requiring the effort of attaching a separate pressing device to the lithium-ion battery 1, compared to when the third structural change step S13 is carried out.

[0052] In the second structural change step S12, the lithium-ion battery 1 only needs to be charged while being pressed, and the pressing step of the lithium-ion battery 1 by the pressing device 301 and the charging step of the lithium-ion battery 1 by the charging device 12 may be started simultaneously, or one of them may be started first.

[0053] In the lithium extraction step S5, lithium is preferentially extracted from the disassembled negative electrode material 35 in which lithium was locally deposited during the second structural change step S12. That is, lithium can be selectively extracted from the portion of the negative electrode material 35 corresponding to the portion pressed by the second structural change step S12. Of the multiple disassembled negative electrode materials 35, which portion corresponds to the portion can be identified by visual inspection or based on the portion pressed by the second structural change step S12. This allows for more efficient lithium extraction.

[0054] In the above embodiment, the case in which the presser pair 302 is divided in the width direction B of the battery cell 3 was described as an example, but it may also be divided in the height direction C which is perpendicular to the stacking direction A and the width direction B of the battery cell 3, or it may even be divided in both the width direction B and the height direction C.

[0055] [Third Embodiment] The third embodiment differs in that a third structural change step S13 (see Figure 4) is adopted instead of the structural change step S2 according to the first embodiment. In the third structural change step S13, based on the structural change step S2, the battery cell 3 is charged while its central portion in the width direction B and / or height direction C is pressed in the stacking direction A under predetermined pressing conditions.

[0056] The reuse system 400 according to the third embodiment, as shown in Figure 7, is equipped with a pressing device 301 similar to the reuse system 300 according to the second embodiment, and the lithium-ion battery 1 is provided to the reuse section 10 in the form of a battery cell 3.

[0057] In the third structural change step S13, as shown in Figure 8, charging is performed by activating only the central presser pair 302A located in the center of the battery cell 3 in the width direction B and / or height direction C, among the multiple presser pairs 302, thereby pressing only the central part 3a in the width direction B of the battery cell 3. Therefore, in the third structural change step S13, the battery cell 3 is charged by increasing the pressing force toward the central part 3a in the plane perpendicular to the stacking direction A compared to the remaining parts 3b and 3c in the stacking direction A.

[0058] For example, if the presser pairs 302 are divided into four substantially equal parts in the width direction B, only the two inner presser pairs 302 in the width direction B may be activated. Alternatively, if the presser pairs 302 are divided into five substantially equal parts in the width direction B, only the three inner presser pairs 302 in the width direction B, or only the central presser pair 302 in the width direction B, may be activated. In other words, in the third structural change step S13, the portion of the battery cell 3 that includes the central part 3a but does not include the peripheral part 3z may be pressed.

[0059] As a result, in the battery cell 3, electrolyte tends to escape outward from the peripheral edge 3z at both sides 3b and 3c, making liquefaction and depletion more likely, while in the central part 3a, electrolyte 39 tends to remain because it is separated from the peripheral edge 3z. Therefore, by increasing the pressing force in the central part 3a where electrolyte 39 tends to remain, the portion of the negative electrode material 35 corresponding to the central part 3a can be designated as a lithium deposition site, making it easier to efficiently deposit lithium.

[0060] In the third structural change step S13, the lithium-ion battery 1 only needs to be charged while being pressed. The pressing step of the lithium-ion battery 1 by the pressing device 301 and the charging step of the lithium-ion battery 1 by the charging device 12 may be started simultaneously, or one of them may be started first. That is, after the pressing step by the pressing device 301 is performed, the charging step by the charging device 12 may be performed while the pressing state by the pressing device 301 is maintained.

[0061] [Fourth Embodiment] Figure 9 is a flowchart illustrating the general flow of the reuse of the lithium-ion battery 1 according to the fourth embodiment. As shown in Figure 9, in the fourth embodiment, the gas extrusion process S14 is performed before the structural change process S2. In the gas extrusion process S14, assuming that gas is generated inside the lithium-ion battery 1, the gas is pushed out towards the peripheral edge 3z side of the lithium-ion battery 1 by sequentially pressing it in the stacking direction A under predetermined pressing conditions.

[0062] When gas is generated inside the lithium-ion battery 1, the outside of the lithium-ion battery 1 swells, so the generation of gas can be confirmed by the appearance of the lithium-ion battery 1. In addition, since the internal pressure of the lithium-ion battery 1 fluctuates due to the generation of gas, the generation of gas can also be confirmed by the fluctuation in the pressing force of the pressing device 301 described later.

[0063] Generally, when gas is generated within the lithium-ion battery 1, the movement of electrons between the positive electrode material 31 and the negative electrode material 35 is inhibited by the gas, making it difficult for charge-discharge reactions to occur. This gas is a by-product generated from the electrolyte 39 during the charge-discharge reactions in the primary and secondary use of the lithium-ion battery 1. This gas is, for example, methane and / or carbon dioxide.

[0064] The reuse system 500 according to the fourth embodiment, as shown in Figure 7, is equipped with a pressing device 301 similar to the reuse system 300 according to the second embodiment, and the lithium-ion battery 1 is provided to the reuse section 10 in the form of a battery cell 3.

[0065] In the gas extrusion process S14, the gas generated inside the battery cell 3 is pushed out toward the peripheral edge 3z by sequentially operating the presser pairs 302 of multiple sets of presser pairs 302 from one end 3b to the other end 3c in the width direction B, or sequentially operating them from the central part 3a in the width direction B to both sides 3b and 3c in the width direction B. Therefore, if gas is generated inside the battery cell 3, the process further includes a gas extrusion process before the structural change process S2 in which the gas is pushed out toward the peripheral edge 3z of the negative electrode material 35 in an in-plane direction perpendicular to the stacking direction A.

[0066] For example, as shown in Figure 10A, the central part 3a in the width direction B of the battery cell 3 may be pressed first, and then, as shown in Figure 10B, the sides 3b and 3c in the width direction B may be pressed as well. As a result, the gas is pushed out from the central part 3a side to the sides 3b and 3c side of the battery cell 3 in the width direction B. Note that the parts 3a, 3b, and 3c of the battery cell 3 remain pressed to prevent the pushed-out gas from flowing back into the central part 3a, etc. of the battery cell 3.

[0067] Furthermore, as shown in Figure 11A, after pressing one end 3b in the width direction B of the battery cell 3, the central part 3a in the width direction may be additionally pressed as shown in Figure 11B, and the other end 3c in the width direction B may be additionally pressed as shown in Figure 11C. As a result, the gas is pushed out from the end 3b side to the other end 3c side in the width direction B. It is preferable that the parts 3a, 3b, and 3c of the battery cell 3 remain pressed so that the pushed-out gas does not flow back into the central part 3a, etc. of the battery cell 3.

[0068] As a result, by pushing the gas toward the peripheral portion 3z, it is easier to ensure that the electrolyte 39 is present around the negative electrode material 35. Consequently, even in a battery cell 3 where gas has been generated, a charging reaction can be initiated in the negative electrode material 35. Therefore, even in a battery cell 3 where gas has been generated, the structural change of the negative electrode electrolyte surface can be promoted by charging under localized pressure. As a result, lithium is more easily deposited in the portion of the negative electrode material 35 where the structural change of the negative electrode active material surface has been promoted.

[0069] In the second to fourth embodiments described above, the lithium-ion battery 1 is described as being provided in the form of a battery cell 3 in the reuse process S1, and then undergoes a structural change process, but is not limited to this. The lithium-ion battery 1 may be provided in the form of a battery pack or battery module 4 in the reuse process S1 and / or the lithium deposition process. In this case, the pressing device 301 may be pre-built inside the battery pack or battery module 4.

[0070] The lithium-ion battery 1 reuse system relating to this disclosure is not limited to the configuration described in the above embodiment, and various modifications are possible.

[0071] In the above embodiment, a laminated lithium-ion battery was described as an example, but it is not limited to this. For example, a cylindrical or rectangular lithium-ion battery may be used, which is constructed by winding a strip-shaped laminated electrode body, in which a strip-shaped positive electrode material, a strip-shaped separator, and a strip-shaped negative electrode material are stacked in the stacking direction A, into a cylindrical or rectangular shape. In the case of cylindrical and rectangular types, the stacking direction corresponds to the radial direction perpendicular to the winding direction.

[0072] Although the explanation was given on a cell-by-cell basis, it can also be done on a module-by-module or battery pack-by-battery basis. If done on a battery pack basis, a pressing device, cooling device, etc. may be pre-installed inside the battery pack.

[0073] [Note] The following aspects are provided according to this disclosure. [Aspect 1] A battery processing method for processing a lithium-ion battery comprising a positive electrode material and a negative electrode material, wherein the positive electrode material and the negative electrode material are stacked in a stacking direction, A structural change step is performed in which the lithium-ion battery is charged and discharged to cause a structural change on the surface of the negative electrode active material, A lithium deposition process is performed by charging and discharging the lithium-ion battery to deposit lithium on the negative electrode material. A battery processing method, including the following. [Aspect 2] The battery processing method according to embodiment 1, wherein in the structural change step, a charging current is applied while pressing the negative electrode material. [Aspect 3] The battery processing method according to embodiment 1 or 2, wherein in the structural change step, charging and discharging are performed by pulse charging, in which a charging phase and a charging pause phase are performed alternately. [Aspect 4] A battery processing method according to any one of embodiments 1 to 3, further comprising a gas extrusion step of pushing the gas inside the lithium-ion battery from the central part to the peripheral part in a plane perpendicular to the stacking direction of the negative electrode material, prior to the structural change step. [Aspect 5] The battery processing method according to any one of embodiments 1 to 4, wherein in the lithium deposition step, charging and discharging are performed by pulse charging, in which a charging phase and a charging pause phase are performed alternately. [Aspect 6] A battery processing method according to any one of embodiments 1 to 5, for lithium-ion batteries having an energy density of 600 Wh / L or more. [Aspect 7] A battery processing method according to any one of embodiments 1 to 6, further comprising a lithium extraction step of extracting lithium from the negative electrode material after the lithium deposition step. [Aspect 8] A battery processing method according to any one of embodiments 1 to 7, further comprising a lithium recovery step, in which the extracted lithium is recovered as lithium carbonate by mixing it with carbonated water and then filtering it after the lithium extraction step. [Aspect 9] A battery processing system for processing lithium-ion batteries, which include a positive electrode material and a negative electrode material, A pressing device for pressing at least a portion of the lithium-ion battery and A charge / discharge device for charging and discharging the aforementioned lithium-ion battery, A battery processing system equipped with the following features. [Explanation of Symbols]

[0074] 1. Lithium-ion battery 3 battery cells 4 Battery Modules 10. Reuse Department 12 Charging device 20 Recycling Department 21 Demolition equipment 22 Extraction device 23 Recovery device 31 Positive electrode material 34 Separator 35. Negative electrode material 38. Stacked electrode body 39 Electrolyte 40 cases 100 Reuse Systems 201 Cooling device 301 Pressing device

Claims

1. A battery processing method for processing a lithium-ion battery comprising a positive electrode material and a negative electrode material, wherein the positive electrode material and the negative electrode material are stacked in a stacking direction, A structural change step is performed in which the lithium-ion battery is charged and discharged to cause a structural change on the surface of the negative electrode active material, A lithium deposition process is performed by charging and discharging the lithium-ion battery to deposit lithium on the negative electrode material. A battery processing method, including the following.

2. The battery processing method according to claim 1, wherein in the structural change step, a charging current is applied while pressing the negative electrode material.

3. The battery processing method according to claim 1, wherein in the structural change step, charging and discharging are performed by pulse charging, in which a charging phase and a charging pause phase are performed alternately.

4. The battery processing method according to claim 1, further comprising a gas extrusion step of pushing the gas inside the lithium-ion battery from the central part to the peripheral part in a plane perpendicular to the stacking direction of the negative electrode material, prior to the structural change step.

5. The battery processing method according to claim 1, wherein in the lithium deposition step, charging and discharging are performed by pulse charging, in which a charging phase and a charging pause phase are performed alternately.

6. The battery processing method according to claim 1, applicable to the lithium-ion battery having an energy density of 600 Wh / L or more.

7. The battery processing method according to claim 1, further comprising a lithium extraction step of extracting lithium from the negative electrode material after the lithium deposition step.

8. The battery processing method according to claim 1, further comprising a lithium recovery step, in which, after the lithium extraction step, the extracted lithium is recovered as lithium carbonate by mixing it with carbonated water and then filtering it.

9. A battery processing system for processing lithium-ion batteries, which include a positive electrode material and a negative electrode material, A pressing device for pressing at least a portion of the lithium-ion battery and A charge / discharge device for charging and discharging the aforementioned lithium-ion battery, A battery processing system equipped with the following features.

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