Battery processing method and battery processing system

Abstract

Efficiently recover lithium from lithium-ion batteries. [Solution] A battery processing method for processing a lithium-ion battery 1 including a positive electrode material 31 and a negative electrode material 35 includes a lithium deposition step S2 in which pulse charging is performed on the lithium-ion battery 1 under cooling conditions to deposit lithium on the negative electrode material 35, wherein the pulse charging is performed alternately in a charging phase Fc and a charging pause phase Fs, with at least multiple charging phases Fc being performed, and the lithium-ion battery 1 is cooled during the charging phase Fc.

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 cars 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 recovering lithium from a positive electrode material after increasing the amount of lithium contained in the positive electrode material by discharging a used lithium-ion battery.

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, cobalt, etc. in the case of a ternary system (NMC) for example. To recover valuable substances from the positive electrode active material, the positive electrode material is roasted with a reducing agent and pulverized, and then 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 laborious 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 containing a positive electrode material and a negative electrode material, The lithium deposition step includes a step in which pulse charging is performed on the lithium-ion battery under cooling conditions to deposit lithium on the negative electrode material, In the pulsed charging described above, a charging phase and a charging pause phase are performed alternately, and at least the charging phase is performed multiple times. During the charging phase, the lithium-ion battery is cooled.

[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 charging device that performs pulse charging on the lithium-ion battery, having alternating charging phases and charging pause phases, and having at least multiple such charging phases, A cooling device for cooling the lithium-ion battery during the charging phase, 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]Graph showing the relationship between the charging rate with respect to SOC and the ease of lithium precipitation for each cooling temperature. [Figure 6] Diagram schematically showing pulse charging. [Figure 7] Block diagram schematically showing the reuse part according to the modification example. [Figure 8A] Diagram schematically showing pulse charging according to the modification example. [Figure 8B] Diagram schematically showing pulse charging according to a further modification example. [Figure 9] Block diagram schematically showing the reuse system according to the second embodiment. [Figure 10] Diagram showing the schematic configuration of the pressing device. [Figure 11] Flowchart schematically showing the flow of reuse according to the fourth embodiment. [Figure 12A] Diagram schematically showing an example of the operation of the pressing device. [Figure 12B] Diagram schematically showing an example of the operation of the pressing device following FIG. 12A. [Figure 13A] Diagram schematically showing another example of the operation of the pressing device. [Figure 13B] Diagram schematically showing another example of the operation of the pressing device following FIG. 13A. [Figure 13C] Diagram schematically showing another example of the operation of the pressing device following FIG. 13B.

Mode for Carrying Out the Invention

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

[0012] The method for reusing a lithium-ion battery according to an embodiment of the present invention is A battery processing method for processing a lithium-ion battery containing a positive electrode material and a negative electrode material, The lithium deposition step includes a step in which pulse charging is performed on the lithium-ion battery under cooling conditions to deposit lithium on the negative electrode material, In the pulsed charging described above, a charging phase and a charging pause phase are performed alternately, and at least the charging phase is performed multiple times. During the charging phase, the lithium-ion battery is cooled.

[0013] Furthermore, the battery processing system for processing lithium-ion batteries according to one embodiment of the present invention is A battery processing system for processing lithium-ion batteries, which include a positive electrode material and a negative electrode material, A charging device that performs pulse charging on the lithium-ion battery, having alternating charging phases and charging pause phases, and having at least multiple such charging phases, A cooling device for cooling lithium-ion batteries during the charging phase, It is equipped with.

[0014] [First Embodiment] Hereinafter, a lithium-ion battery reuse system according to the first embodiment of the present invention will be described with reference to the attached drawings. Figure 1 is a schematic block diagram showing a lithium-ion battery reuse system 100. As shown in Figure 1, the reuse system 100 includes a reuse unit 10 that reuses a lithium-ion battery 1 that has been used primarily in, for example, an electric vehicle, and a recycling unit 20 that recovers lithium from the reused lithium-ion battery 1.

[0015] The reuse unit 10 reuses the lithium-ion battery 1, which has been used for its primary purpose, as an energy storage device. Generally, the degradation state of lithium-ion batteries for electric vehicles is determined based on the State of Health (SOH), which indicates how much capacity they have when fully charged compared to when they were new. If the lithium-ion battery 1 is determined to be unsuitable for use in an electric vehicle based on its degree of degradation, it is removed from the vehicle and used in the reuse unit 10 as an energy storage device for various secondary purposes, such as storing renewable energy such as solar power and wind power, or as a backup power source during disasters. For example, if the SOH falls below 70%, it may be determined that it is unsuitable for primary use, i.e., for use in an electric vehicle.

[0016] The reuse unit 10 includes a lithium-ion battery 1 that is secondarily used as an energy 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 any charging pattern. For example, the lithium-ion battery 1 can be continuously charged at a predetermined voltage and current, as well as intermittently charged at a predetermined voltage and current (also called pulse charging). The upper limit of the charging voltage by the charging device 12 is less than or equal to the withstand voltage of the lithium-ion battery 1, for example, 4.3V or less.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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. The battery cell 3 has a laminated 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 laminated electrode body 38 is housed.

[0022] 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 battery cell 3 is elongated rectangular in the width direction B when viewed from the stacking direction A.

[0023] The positive electrode material 31 comprises a positive electrode current collector 32 and a positive electrode active material 33 disposed 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 that are connected to each other at one end (left side in Figure 3) in the width direction B perpendicular to the stacking 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).

[0024] The negative electrode material 35 comprises a negative electrode current collector 36 and a negative electrode active material 37 disposed 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 that are 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.

[0025] 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 lithium hexafluoride phosphate (LiPF6) at a concentration of 1 mol / L.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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, the reuse section 10 performs a lithium deposition process (step S2) following the secondary use. In the lithium deposition process S2, lithium is deposited on the negative electrode material 35. In the lithium deposition process S2, the lithium-ion battery 1 is charged in such a way that lithium is deposited on the negative electrode material 35.

[0031] In the lithium deposition process S2, the lithium-ion battery 1 is charged while being cooled by the cooling device 201 under predetermined cooling conditions. Here, the graph in Figure 5 shows the relationship between SOC (State of Charge) and the charging rate (charging current) at which lithium begins to deposit, for each temperature. Specifically, lithium is more likely to deposit on the negative electrode material 35 when charging is performed on or 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 5, lithium is more likely to deposit in the lithium-ion battery 1 as the SOC increases and / or as the temperature decreases.

[0032] Therefore, in the lithium deposition process S2, the lithium-ion battery 1 is charged at a current rate (also called the charging rate) Ch (see Figure 6) at which lithium is deposited on the negative electrode material 35 relative to the cooling temperature. When the current rate during charging in normal use is Cn (see Figure 6), the current rate Ch in the lithium deposition process S2 is equal to or greater than the current rate Cn. For example, the lithium-ion battery 1 may be charged at a current rate at which lithium begins to deposit on the negative electrode material 35, which allows for lithium deposition with less energy. For example, by cooling the lithium-ion battery 1, lithium can be deposited on the negative electrode material 35 even if the charging rate is kept low.

[0033] In the lithium deposition process S2, pulse charging, which involves intermittent charging, is employed. 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 preferably performed only during the charging phase Fc and not during the charging pause phase Fs.

[0034] 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 in the electrolyte 39 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 charging pause phase Fs in 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.

[0035] For example, the charging phase Fc is performed until the lithium ion concentration in the electrolyte 39 near the negative electrode active material 37 falls below a first concentration, and is performed for, for example, 30 seconds. The first concentration is a concentration at which lithium deposition on the negative electrode material 35 is unlikely to occur. The charging pause phase Fs is performed until the lithium ion concentration in the electrolyte 39 near the negative electrode active material 37 rises to or exceeds a second concentration, and is performed for, for example, 30 seconds. The second concentration is a concentration at which lithium deposition on the negative electrode material 35 is likely to occur.

[0036] Next, the lithium-ion battery 1 is removed from the reuse section 10 and the battery dismantling process (step S3) is performed by the dismantling device 21. In the battery dismantling process S3, 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.

[0037] Next, a lithium extraction process (step S4) is carried out. In lithium extraction process S4, lithium is extracted from the disassembled negative electrode material 35. In lithium extraction process S4, 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, after which the negative electrode material 35 is leached with water and filtered, and an aqueous solution containing lithium ions is extracted.

[0038] 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.

[0039] In other words, the battery processing method according to this embodiment is A battery processing method for processing a lithium-ion battery 1 comprising a positive electrode material 31 and a negative electrode material 35, The process includes a lithium deposition step S2 in which lithium is deposited on the negative electrode material 35 by pulse charging the lithium-ion battery 1 under cooling conditions. In the pulse charging described above, the charging phase Fc and the charging pause phase Fs are performed alternately, and at least the charging phase Fc is performed multiple times. During the charging phase Fc, the lithium-ion battery 1 is cooled.

[0040] Furthermore, the reuse system (battery processing system) 100 according to this embodiment is A battery processing system for processing a lithium-ion battery 1 comprising a positive electrode material 31 and a negative electrode material 35, A charging device 12 performs pulse charging on a lithium-ion battery 1, having alternating charging phases Fc and charging pause phases Fs, and having at least multiple such charging phases. A cooling device 201 cools the lithium-ion battery 1 during the charging phase. It is equipped with.

[0041] As a result, by charging under cooling conditions, lithium can be deposited on the negative electrode material 35 even without high-rate charging. Therefore, the charging current can be reduced, resulting in energy savings.

[0042] Furthermore, during the charging pause phase in pulse charging, the decrease in lithium ion concentration near the negative electrode active material 37 is mitigated. Therefore, the decrease in lithium ion concentration near the negative electrode active material 37 due to lithium deposition on the negative electrode material 35 during the charging phase is mitigated during the charging pause phase, making it easier to effectively deposit lithium on the negative electrode material 35 in subsequent charging phases. Compared to continuous charging, intermittent charging by pulse charging makes it easier to deposit lithium on the negative electrode material 35 more effectively.

[0043] Furthermore, cooling of the lithium-ion battery 1 is performed only during the charging phase. In other words, cooling of the lithium-ion battery 1 is stopped during the charging pause phase.

[0044] As a result, by stopping cooling during the charging pause phase, the electrolyte 39 is less likely to be kept at a low temperature, thus suppressing a decrease in the viscosity of the electrolyte 39. Consequently, lithium ions move more easily in the electrolyte 39, promoting their movement towards the vicinity of the negative electrode active material 37. Therefore, the decrease in lithium ion concentration in the negative electrode active material 37 is more easily mitigated.

[0045] Figure 7 shows a modified reuse unit 110. In the modified version, the reuse unit 110 is further equipped with a discharge device 111. The discharge device 111 discharges the lithium-ion battery 1 at a predetermined voltage and current. By providing the discharge device 111, the lithium-ion battery 1 may be discharged during the charge pause phase Fs. In other words, the charge pause phase Fs may be configured as a discharge phase Fd. As other examples of providing a discharge phase Fd, for example, as shown in Figure 8A, the discharge phase Fd may be added between the charge phase Fc and the charge pause phase Fs, or as shown in Figure 8B, the discharge phase Fd may be added in the middle of the charge pause phase Fs.

[0046] By adding a discharge phase Fd, lithium ions are more readily attracted to the negative electrode active material 37 and moved closer to it. As a result, the lithium ion concentration near the negative electrode active material 37 is easily increased, making it easier for lithium to be deposited more efficiently by the negative electrode material 35 in the subsequent charging phase Fc.

[0047] In the above embodiment, the type of lithium-ion battery 1 is not particularly limited, but preferably, the lithium-ion battery 1 is a high-output type (also called a power type) rather than a capacity type (also called an energy type). High-output lithium-ion batteries have a lower density of negative electrode active material 37 compared to capacity type lithium-ion batteries, and therefore have superior lithium ion uptake into the negative electrode active material 37. As a result, lithium ions can be more efficiently uptaken into the negative electrode active material 37 during the charging pause phase Fs in pulse charging, and lithium can be more efficiently deposited on the negative electrode material 35 during the subsequent charging phase Fc. In other words, the effects of the present invention are more favorably exhibited when the lithium-ion battery 1 is a high-output type.

[0048] 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.

[0049] In the above embodiment, the case in which the lithium-ion battery 1 is provided to the reuse process S1 in the form of a battery pack and then the lithium deposition 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 to the reuse process S1 and / or the lithium deposition process S2 in the form of a battery module 4 or a battery cell 3.

[0050] [Second Embodiment] The second embodiment differs in that a second lithium deposition step S12 (see Figure 4) is used instead of the lithium deposition step S2 according to the first embodiment. In the second lithium deposition step S12, based on the lithium deposition step S2, the lithium-ion battery 1 is further pressed in the stacking direction A under predetermined pressing conditions during pulse charging.

[0051] Figure 9 is a schematic block diagram showing the reuse system 300 according to the second embodiment. As shown in Figure 9, 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.

[0052] In the second embodiment, it may be assumed that the lithium-ion battery 1 has not deteriorated much and that the electrolyte 39 has spread throughout the entire battery cell 3.

[0053] 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 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. The pressing device 301 is not particularly limited, and any actuator such as a hydraulic cylinder or a pneumatic cylinder can be used.

[0054] Figure 10 is a schematic diagram of the pressing device 301. Figure 10 also schematically shows the battery cell 3 that is pressed by the pressing device 301. As shown in Figure 10, 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 one-side presser pair 302B located on one side of the width direction B (left side in Figure 10), and a other-side presser pair 302C located on the other side of the width direction B (right side in Figure 10). The presser pairs 302 are not limited to three, but may be divided into two or four or more.

[0055] In the second lithium deposition 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 lithium deposition 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 rest. Generally, in order to generate a charge-discharge reaction within the lithium-ion battery 1, it is necessary to press (i.e., restrain) the battery cell 3 in the stacking direction. In the second lithium deposition step S12, the battery cell 3 is pressed with a pressing force that is at least necessary for the charge-discharge reaction to occur. For example, this pressing force is 10 kPa or more and 1 MPa or less.

[0056] As a result, in addition to the effects of pulse charging under cooling, the following effects are achieved. Specifically, when charging the lithium-ion battery 1, increasing the pressing force in at least a portion of the battery promotes (concentrates) the charging reaction in the negative electrode material 35 corresponding to that portion. As a result, the charging current is concentrated in the area where the charging reaction is promoted, so high-rate charging is performed in that area, making it easier to deposit lithium locally. 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 the area where electrolyte remains by increasing the pressing force in that area.

[0057] "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 lithium deposition step S12. In this way, when the second lithium deposition step S12 is performed using the pressing device provided in the lithium-ion battery 1 that has been reused, it is possible to perform the work efficiently without the hassle of attaching a separate pressing device to the lithium-ion battery 1, compared to when the second lithium deposition step S12 is performed by attaching a separate pressing device to the lithium-ion battery 1.

[0058] In the second lithium deposition step S12, the lithium-ion battery 1 only needs to be charged while being pressed. The pressing of the lithium-ion battery 1 by the pressing device 301 and the charging of the lithium-ion battery 1 by the charging device 12 may start simultaneously, or one may start first. That is, after pressing by the pressing device 301 is performed, charging by the charging device 12 may be performed while the pressing state by the pressing device 301 is maintained.

[0059] In the lithium extraction step S4, lithium is selectively extracted from the portion of the disassembled negative electrode material 35 in which lithium was locally deposited during the second lithium deposition step S12. That is, lithium is selectively extracted from the portion of the negative electrode material 35 corresponding to the portion pressed by the second lithium deposition 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 lithium deposition step S12. This allows for more efficient extraction of lithium.

[0060] 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.

[0061] [Third Embodiment] The third embodiment differs in that a third lithium deposition step S13 (see Figure 4) is used instead of the lithium deposition step S2 according to the first embodiment. In the third lithium deposition step S13, based on the lithium deposition 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.

[0062] In the third embodiment, the degradation of the lithium-ion battery 1 is more advanced compared to the lithium-ion battery 1 in the third embodiment, and it may be assumed that the electrolyte 39 has depleted, particularly at the peripheral edge 3z of the battery cell 3.

[0063] The reuse system 400 according to the third embodiment, as shown in Figure 9, 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.

[0064] In the third lithium deposition step S13, as shown in Figure 10, 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 lithium deposition 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.

[0065] 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. Also, 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 lithium deposition 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.

[0066] As a result, in addition to the effects of pulse charging under cooling, the following effects are achieved. Specifically, in the battery cell 3, electrolyte tends to escape outward from the peripheral edge 3z at both sides 3b and 3c, leading to depletion of electrolyte, 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, lithium can be efficiently deposited on the negative electrode material 35 corresponding to the central part 3a.

[0067] In the third lithium deposition 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.

[0068] [Fourth Embodiment] Figure 11 is a flowchart schematically showing the reuse process of the lithium-ion battery 1 according to the fourth embodiment. As shown in Figure 11, in the fourth embodiment, the gas extrusion process S14 is performed before the lithium deposition 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.

[0069] 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.

[0070] 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.

[0071] The reuse system 500 according to the fourth embodiment, referring to Figure 9, 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.

[0072] 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 lithium deposition 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.

[0073] For example, as shown in Figure 12A, the central part 3a in the width direction B of the battery cell 3 may be pressed first, and then, as shown in Figure 12B, 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.

[0074] Furthermore, as shown in Figure 13A, 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 13B, and the other end 3c in the width direction B may be additionally pressed as shown in Figure 13C. As a result, the gas is pushed out from the end 3b side to the other end 3c side 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.

[0075] As a result, in addition to the effects of pulse charging under cooling, the following effects are achieved. Specifically, 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. As a result, 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 charging reaction can be promoted by high-rate charging or charging under cooling, or the charging reaction can be locally 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 charging reaction has been promoted.

[0076] 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 the lithium deposition process is carried out as an example, but it 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.

[0077] 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.

[0078] 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 batteries, the stacking direction corresponds to the radial direction perpendicular to the winding direction.

[0079] 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.

[0080] [Note] According to the lithium-ion battery reuse systems 100, 300, 400, and 500 relating to this disclosure, the following embodiments are provided.

[0081] [Aspect 1] A battery processing method for processing a lithium-ion battery containing a positive electrode material and a negative electrode material, The lithium deposition step includes a step in which pulse charging is performed on the lithium-ion battery under cooling conditions to deposit lithium on the negative electrode material, In the pulsed charging described above, a charging phase and a charging pause phase are performed alternately, and at least the charging phase is performed multiple times. During the charging phase, the lithium-ion battery is cooled. Battery disposal method.

[0082] [Aspect 2] This applies to lithium-ion batteries with a power density of 4000 kW / L or more. The battery processing method described in Embodiment 1.

[0083] [Aspect 3] The lithium-ion battery further contains an electrolyte, and is constructed by stacking the positive electrode material and the negative electrode material in a stacking direction. The battery processing method further includes, if gas is generated in the lithium-ion battery, a gas extrusion step, before the lithium deposition step, in which the gas is pushed out from the center to the periphery of the lithium-ion battery in an in-plane direction perpendicular to the stacking direction. The battery processing method according to embodiment 1 or 2.

[0084] [Aspect 4] The pulse charging further includes a discharge phase for discharging the lithium-ion battery. A battery processing method according to any one of embodiments 1 to 3.

[0085] [Aspect 5] The lithium-ion battery further contains an electrolyte, and is constructed by stacking the positive electrode material and the negative electrode material in a stacking direction. In the lithium deposition step, the lithium-ion battery is subjected to increased pressure in the stacking direction in the central part of the plane perpendicular to the stacking direction compared to the remaining part. A battery processing method according to any one of embodiments 1 to 4.

[0086] [Aspect 6] The battery processing method further includes a lithium extraction step of extracting lithium from the negative electrode material, The lithium extraction step includes filtering the negative electrode material after leaching it. A battery processing method according to any one of embodiments 1 to 5.

[0087] [Aspect 7] The battery processing method further includes a lithium recovery step that follows the lithium extraction step, The lithium recovery step recovers the extracted lithium as lithium carbonate by immersing it in carbonated water and then filtering it. The battery processing method described in embodiment 6.

[0088] [Aspect 8] A battery processing system for processing lithium-ion batteries, which include a positive electrode material and a negative electrode material, A charging device that performs pulse charging on the lithium-ion battery, having alternating charging phases and charging pause phases, and having at least multiple such charging phases, A cooling device for cooling the lithium-ion battery during the charging phase, A battery processing system equipped with the following features. [Explanation of Symbols]

[0089] 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 containing a positive electrode material and a negative electrode material, The lithium deposition step includes a step in which pulse charging is performed on the lithium-ion battery under cooling conditions to deposit lithium on the negative electrode material, In the pulsed charging described above, a charging phase and a charging pause phase are performed alternately, and at least the charging phase is performed multiple times. During the charging phase, the lithium-ion battery is cooled. Battery disposal method.

2. This applies to lithium-ion batteries with an output density of 4000 kW / L or more. The battery processing method according to claim 1.

3. The lithium-ion battery further contains an electrolyte, and is constructed by stacking the positive electrode material and the negative electrode material in a stacking direction. The battery processing method further includes, if gas is generated in the lithium-ion battery, a gas extrusion step, before the lithium deposition step, in which the gas is pushed out from the center to the periphery of the lithium-ion battery in an in-plane direction perpendicular to the stacking direction. The battery processing method according to claim 1.

4. The pulse charging further includes a discharge phase for discharging the lithium-ion battery. The battery processing method according to claim 1.

5. The lithium-ion battery further contains an electrolyte, and is constructed by stacking the positive electrode material and the negative electrode material in a stacking direction. In the lithium deposition step, the lithium-ion battery is subjected to increased pressure in the stacking direction in the central part of the plane perpendicular to the stacking direction compared to the remaining part. The battery processing method according to claim 1.

6. The battery processing method further includes a lithium extraction step of extracting lithium from the negative electrode material, The lithium extraction step includes filtering the negative electrode material after leaching it. The battery processing method according to claim 1.

7. The battery processing method further includes a lithium recovery step that follows the lithium extraction step, The lithium recovery step recovers the extracted lithium as lithium carbonate by immersing it in carbonated water and then filtering it. The battery processing method according to claim 6.

8. A battery processing system for processing lithium-ion batteries, which include a positive electrode material and a negative electrode material, A charging device that performs pulse charging on the lithium-ion battery, having alternating charging phases and charging pause phases, and having at least multiple such charging phases, A cooling device for cooling the lithium-ion battery during the charging phase, A battery processing system equipped with the following features.

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