Battery recycling methods

Abstract

This provides a simple recycling method that increases the purity of metals to be recycled and recovers them. [Solution] A method for recycling a lithium-ion battery 1 comprising an outer casing 10 and a battery body 20 housed in the outer casing 10, comprising: a groove forming step S31 for forming a groove 13 in the outer casing for breaking the outer casing 10; an initial breaking step S33 for performing initial breaking at a weakened portion 14 formed in the outer casing 10; and a breaking step for breaking the outer casing 10 at the groove 13 through the broken weakened portion 14, thereby removing the battery body 20 from the outer casing 10 and recycling the battery. Preferably, the groove 13 is set to have a width of 0.1 to 5 mm, and the weakened portion 14 is set to have a width of 0.1 to 5 mm, and preferably the thickness t2 of the outer casing 10 at the position where the weakened portion is formed is 0.4 times or less, preferably 0.2 times or less, and most preferably 0.1 times or less, the thickness t of the outer casing 10.

Description

Technical Field

[0001] The present invention relates to a method for recycling batteries.

Background Art

[0002] In recent years, efforts towards recycling have been emphasized more than ever. In order to recover valuable metals used in electrodes of batteries such as lithium-ion batteries, various methods for recycling batteries have been proposed. For example, a battery recycling method described in Patent Document 1 is known. In the battery recycling method described in Patent Document 1, a battery pack is directly baked in a non-oxidizing atmosphere or a reducing atmosphere to thermally decompose resin materials and insulating materials in the battery pack, thereby causing an electrical short circuit in the battery pack to discharge in a baking step. Then, the baked battery pack is separated into assembled batteries and parts other than assembled batteries, and in the step of pulverizing the separated single cells (lithium-ion secondary batteries), the storage battery baked together with the outer casing of the single cell is pulverized, and the pulverized material is sieved to recover valuable metals.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Although the method described in Patent Document 1 separates the roasted battery pack into battery packs and other components, roasting and crushing the battery pack containing the battery packs at high temperatures results in all the components constituting the lithium-ion secondary battery being mixed together. As a result, in the metal recovery process, there is a problem in that the purity of the metal to be recycled is considerably lower compared to the valuable metals used in the original lithium-ion secondary battery. On the other hand, if one tries to increase the purity of the metal, it becomes necessary to safely dismantle the high-voltage battery, which requires many processes and is costly.

[0005] The object of the present invention is to solve the problems of the prior art described above and to provide a battery recycling method that can easily improve the purity of the valuable metals to be recycled and recover them. [Means for solving the problem]

[0006] The present invention relates to a battery recycling method comprising an outer casing and a battery body housed in the outer casing, the method comprising: a groove forming step of forming grooves in the outer casing for breaking the outer casing; an initial breaking step of performing initial breaking at a weakened portion formed in the outer casing; and a breaking step of breaking the outer casing at the grooves via the broken weakened portion, wherein the battery is recycled by removing the battery body from the outer casing. By rupturing the outer casing through a weakened section, significant external force is not required, and the casing can be easily removed. Furthermore, since the battery body can be crushed or otherwise processed after the casing is removed to recover valuable metals, the purity of the valuable metals to be recycled can be increased during recovery.

[0007] A preferred embodiment of the present invention is that the thickness of the exterior body in the portion where the weakened portion is formed is thinner than the thickness of the exterior body in the portion where the groove is formed.

[0008] It is preferable to include a weakening portion forming step in which the weakened portion is formed on the outer casing. By forming the weakened portion, it is possible to form the weakened portion in an appropriate location on batteries that have been collected as waste.

[0009] It is preferable to form the groove so that it is continuous with the weakened portion. By making the groove and the weakened portion continuous, the initial fracture at the weakened portion can be followed by the fracture of the groove.

[0010] In the initial fracture step, it is preferable to perform the initial fracture of the weakened portion of the outer casing by pressing near the weakened portion. By pressing near the outer casing, the weakened portion can be shear-fractured, allowing for simple, low-cost, and time-efficient initial fracture of the weakened portion.

[0011] In the initial fracture step, it is preferable to perform the initial fracture of the weakened portion by pressing the outer casing to increase its internal pressure. By pressing the outer casing to increase its internal pressure, the weakened portion can be initially fractured easily, at low cost, and without taking much time.

[0012] In the initial fracture step, it is preferable to perform the initial fracture by applying a chemical solution to the weakened portion. By applying the chemical solution, the weakened portion can be fractured easily and safely.

[0013] In the initial fracture step, it is preferable to perform the initial fracture by heating the outer casing to increase its internal pressure. By heating the outer casing to increase its internal pressure, the weakened portion can be fractured easily and at low cost.

[0014] In the initial fracture step, it is preferable to perform the initial fracture of the weakened portion of the outer casing by cutting the weakened portion. By cutting the weakened portion of the outer casing, the weakened portion can be fractured very easily.

[0015] Preferably, the process further includes a heating step for heating the removed battery body. Since the battery body is removed from the outer casing, energy consumption in the heating step can be reduced.

[0016] In the heating step, it is preferable to unwind the winding body, which consists of the positive and negative electrodes and the separator that constitute the battery body, before heating. By unwinding the winding body before heating, energy consumption in the heating step can be further reduced.

[0017] Preferably, the storage battery has a negative terminal and a positive terminal on one of the ceiling surfaces constituting the outer casing, and the weakened portion and the groove are formed on a side surface continuous with the ceiling surface. By forming the weakened portion and groove in this way, the battery body is also fixed to the ceiling surface of the outer casing, so after breaking the outer casing, the battery body can be easily removed from the outer casing by grasping and lifting the negative terminal and positive terminal.

[0018] In a preferred embodiment of the present invention, in the groove forming step, two grooves are formed on the side surface of the exterior body; in the initial fracture step, an initial fracture is performed at the weakened portion connected to either of the two grooves; and thereafter, in the fracture step, the wall surface of the exterior body between the grooves is peeled off and fractured along the grooves. [Effects of the Invention]

[0019] According to the present invention, it is possible to easily increase the purity of valuable metals that are subject to recycling and recover them. [Brief explanation of the drawing]

[0020] [Figure 1] A schematic perspective view of the lithium-ion battery to be recycled in Embodiment 1. [Figure 2] A flowchart illustrating each step of the recycling method in Embodiment 1. [Figure 3] A flowchart illustrating the battery disassembly process in Embodiment 1. [Figure 4] Schematic perspective view of a lithium-ion battery for explaining the groove and weakened portion of Embodiment 1. [Figure 5] Schematic partial cross-sectional view of a lithium-ion battery for explaining the groove and weakened portion of Embodiment 1. [Figure 6] Schematic perspective view of a lithium-ion battery for explaining the initial fracture process of Embodiment 1. [Figure 7] Schematic perspective view of a lithium-ion battery for explaining the fracture process of Embodiment 1. [Figure 8] Schematic perspective view of a lithium-ion battery for explaining the groove and weakened portion of Embodiment 2. [Figure 9] Schematic perspective view of a lithium-ion battery for explaining the fracture process of Embodiment 2. [Figure 10] Schematic partial perspective view of a lithium-ion battery for explaining the groove and weakened portion of the modification. [Figure 11] Schematic partial perspective view of a lithium-ion battery for explaining the groove and weakened portion of the modification. [Figure 12] Schematic partial cross-sectional view of a lithium-ion battery for explaining the weakened portion of the modification.

MODE FOR CARRYING OUT THE INVENTION

[0021] (Embodiment 1) The battery recycling method of the present embodiment will be described with reference to FIGS. 1 to 7. The battery targeted by the battery recycling method of the present embodiment is not particularly limited, but in the present embodiment, for example, it is a lithium-ion battery 1 as shown in FIG. 1. The lithium-ion battery 1 of the present embodiment is used as a lithium-ion secondary battery that constitutes an in-vehicle battery pack, and the battery pack is formed by connecting a plurality of lithium-ion batteries 1 in series or in parallel. By implementing the recycling method of the present embodiment on the battery pack recovered as waste, valuable metals can be recovered with high efficiency.

[0022] The lithium-ion battery 1 is of a type called a prismatic cell and has a hexahedral shaped casing 10. The casing 10 comprises a case 11 in which the battery body 20 is housed and a top surface 12 that seals the case 11. The top surface 12 and the case 11 are sealed together by welding or the like and are integrated. The battery body 20 has a wound body 21 and an electrolyte inside and is sealed. The wound body 21 is composed of a positive electrode, a negative electrode, and a separator provided between them, which are wound together (not shown). In addition, two terminals 30 (positive electrode terminal and negative electrode terminal) are provided on the top surface 12 of the casing 10, and these terminals 30 are fixed to the battery body 20 so as to connect to the positive electrode and negative electrode that constitute the wound body 21 within the casing 10, respectively. In this embodiment, case 11 is made of aluminum with a thickness of approximately 0.5 to 1.0 mm, and the ceiling surface 12 is made of aluminum with a thickness of approximately 2 mm or more.

[0023] The battery recycling method of this embodiment will be explained with reference to Figure 2. The battery recycling method consists of a discharge step S10 in which the collected battery pack is discharged to ensure safety during the work, a pack disassembly step S20 in which the discharged battery pack is disassembled to obtain each lithium-ion battery 1, a battery disassembly step S30 in which the obtained lithium-ion battery 1 is disassembled and the outer casing 10 and the wound body 21 are separated, an outer casing recovery step S40 in which the separated outer casing 10 is recovered, a heating step S50 in which the separated wound body 21 is heated, a crushing step S60 in which the heated wound body 21 is crushed, and a recovery step S70 in which the crushed material is sieved to recover the metal.

[0024] In the discharge step S10, a known discharge method can be employed. For example, this could be a method of natural discharge by storing the battery pack for a long period of time, or a method of forced discharge using a resistor or the like. Next, in the pack dismantling step S20, the frame of the discharged battery pack is dismantled to obtain multiple lithium-ion batteries 1 from the battery pack. Note that if the lithium-ion batteries 1 do not take the structure of a battery pack and are collected as individual waste, this pack dismantling step S20 is unnecessary. Also, if protective equipment is used when performing the pack dismantling step S20, the discharge step S10 may not be necessary.

[0025] The battery disassembly process S30 will be explained using Figures 3 to 7. The battery disassembly process S30 comprises a groove forming process S31 for forming a groove 13 in the outer casing 10 for breaking the outer casing 10, a weakening part forming process S32 for forming a weakened part 14 in the outer casing 10, an initial breaking process S33 for performing an initial break at the weakened part 14 formed in the outer casing 10, a breaking process S34 for breaking the outer casing 10 at the groove 13 through the broken weakened part 14, and a removal process S35 for removing the battery body 20 from the broken outer casing 10. In this embodiment, a weakened part 14 is formed in the case 11 of the outer casing 10, and an initial break is performed at the weakened part 14 first, making it possible to easily break the outer casing 10 without requiring a large external force.

[0026] Here, the grooves 13 and weakened portion 14 formed in the outer casing 10 will be described. The grooves 13 are for breaking the outer casing 10 and are formed on the outer circumference of the side surface of the outer casing 10, excluding the area where the weakened portion 14 is formed. As shown in Figure 4, a curved groove 13 is preferable to a straight groove because it makes it easier to break the outer casing 10.

[0027] The weakened portion 14 is a portion of the exterior body 10 that is configured to have lower strength than the portion where the groove 13 is formed. In this embodiment, the weakened portion 14 is continuous with the groove 13 and is formed over a region R1 on the front side surface of the exterior body 10 in Figure 4 (the side surface continuous with the short side of the ceiling surface 12). Specifically, as shown in Figure 5(2), the weakened portion 14 is formed such that the thickness t2 of the exterior body 10 in the portion where the weakened portion 14 is formed is thinner than the thickness t1 of the exterior body 10 in the portion where the groove 13 is formed, as shown in Figure 5(1). As a result, the weakened portion 14 has lower strength than the groove 13, and the weakened portion can be easily fractured in the initial fracture process S33. The weakened portion 14 is also provided in a gently curved shape, similar to the groove 13, but is not limited to this and may be straight.

[0028] In the groove formation process S31 and the weakened portion formation process S32, both the groove 13 and the weakened portion 14 are formed by notching using a cutting machine or the like. In Figure 5, both the groove 13 and the weakened portion 14 are shown as notched grooves formed by a cutting machine, but this is not limited to this, and any type may be used. Furthermore, in the groove formation process S31 and the weakened portion formation process S32, if the structure of the lithium-ion battery 1 is known in advance from a design drawing or the like, it is preferable to refer to the design drawing to confirm the thickness and structure of the outer casing 10 before forming the groove 13 and the weakened portion 14.

[0029] Furthermore, since the lithium-ion battery 1 is a waste product in this invention, it may already be deformed at the time of collection. In this case, it is preferable to form the weakened portion 14 while measuring the thickness and shape of the outer casing 10 using, for example, an ultrasonic thickness gauge. For example, when manufacturing the outer casing 10, markings or the like indicating the groove positions for forming the weakened portion 14 may be processed in advance.

[0030] The groove 13 is preferably set to have a width of 0.1 to 5 mm. In contrast, the weakened portion 14 is preferably configured such that it has a width of 0.1 to 5 mm, and the thickness t2 of the outer casing 10 at the location where the weakened portion is formed is 0.4 times or less, preferably 0.2 times or less, and most preferably 0.1 times or less, the thickness t of the outer casing 10.

[0031] The formation location of the weakened portion 14 (height on the exterior body 10) is preferably a position where it is easy to apply an external force for initial fracture in the initial fracture step S33 described below. In this embodiment, it is formed on the upper side of the exterior body 10, particularly close to the ceiling surface 12. The weakened portion 14 can be formed on any side surface of the exterior body 10, and since the side surface is often thinner than the ceiling surface 12, the side surface is preferable for forming the weakened portion 14. Furthermore, from the viewpoint of ease of initial fracture, the length of the weakened portion 14 should be about 0.2 to 0.8 times the length of the shorter side of the ceiling surface 12 of the exterior body 10.

[0032] Furthermore, the depth of the groove in the weakened portion 14 does not have to be constant. For example, it may be deeper at the center of region R1 and shallower at the edge of region R1, and may be formed to be continuous with the groove 13. It is also possible to provide multiple weakened portions 14 for a single groove 13.

[0033] In this embodiment, instead of directly breaking the outer casing 10 by mechanical means, that is, instead of breaking the outer casing 10 so that it penetrates directly to its interior, grooves 13 and weakened portions 14 are first formed on the surface of the outer casing 10, and then broken in the initial breaking step S33. This prevents damage to the battery body 20 placed inside the outer casing 10, which could cause the electrolyte inside the battery body 20 to spill out, and also prevents sparks from flying when the casing is broken.

[0034] After the groove formation process S31 and the weakened portion formation process S32, an initial fracture process S33 is performed. In the initial fracture process S33, an external force is applied to the weakened portion 14 from the outside to cause initial fracture at the weakened portion 14, forming a portion that penetrates to the inside of the outer casing 10. Any known method can be applied to apply the external force, but in this embodiment, as shown in Figure 6, in the initial fracture process S33, both sides of the outer casing 10 are held by a holding jig P1, and in that state, the area near the weakened portion 14 of the outer casing 10 is pressed with a pressing jig P2 that presses on the side where the weakened portion 14 is formed. In this case, since the height of the pressing jig P2 is lower than the position where the weakened portion 14 is formed on the outer casing 10, when the outer casing 10 is pressed, shear failure occurs at the weaker weakened portion 14, and the weakened portion 14 is initially fractured.

[0035] Furthermore, it is possible to increase the internal pressure of the outer casing 10 by heating or pressing it, thereby causing the weakened portion 14 to fracture initially. In this case, depending on the structure of the outer casing 10 and the formation state of the weakened portion 14, for example, initial fracture of the outer casing 10 can be achieved by heating or other means to increase the internal pressure to less than 1.5 MPa.

[0036] Furthermore, in the initial fracture process, the weakened portion 14 may be subjected to direct pressure and indentation to perform the initial fracture, or another member may be pressed into the weakened portion 14 to cut it.

[0037] Next, in the breaking step S34, the holding jig P1 and the pressing jig P2 are removed, and while the case 11 is held by another holding means (not shown), an external force is applied by gripping the terminal 30 and pulling it upward, causing the groove 13 to break starting from the weakened portion 14 that was initially broken. That is, the groove 13 functions as a cutting guide groove, and the outer casing 10 breaks along the groove 13 starting from the weakened portion 14. In this case, if there is no initial breaking step S33 and only the breaking step S34, a large external force is required to break the outer casing 10. However, with the recycling method of this embodiment, since the weakened portion 14 is broken by the initial breaking, the groove 13 can be broken with a small external force, so the outer casing 10 can be easily removed, which is preferable. Furthermore, when applying the external force upward, bending stress or torsional stress may be applied.

[0038] Once the outer casing 10 is completely broken, the battery body 20 is fixed to the top surface 12 via the terminals 30, so in the removal process S35, the battery body 20 can be removed directly from the outer casing 10. This separates the broken case 11 from the battery body 20. In this embodiment, as shown in Figure 1, a lithium-ion battery 1 is used in which the terminals are provided only on the top surface, so the battery body 20 can be easily removed from the outer casing 10 by grasping the two electrodes and lifting it up, which is preferable.

[0039] After the battery dismantling process S30, the separated outer casing 10 (case 11) is recovered in the outer casing recovery process S40. The heating process S50 to the recovery process S70 are performed in parallel with or simultaneously with the outer casing recovery process S40. In the heating process S50, the battery body 20 removed from the case 11 is heated together with the top surface 12 and terminals 30 of the outer casing 10. The heating process S50 is performed in a firing furnace at a heating temperature of 200°C or less, preferably 160°C or less. Conventionally, in the roasting process, the outer casing 10 was roasted together, so it was heated to about 500-600°C, but in this embodiment, the heating temperature only needs to be higher than the melting point of the organic solvent contained in the battery body 20, so it is possible to suppress the energy consumption during heating. In the subsequent recovery process S70, for example, when recovering metal using the magnetism of the metal, it is necessary to reduce the cobalt contained in the positive electrode to metallic cobalt, which requires heating to over 500°C. However, even in this case, the roasting time is shorter compared to roasting the entire casing, thus reducing energy consumption.

[0040] The heating method can be selected from a range of options, including not only firing but also heating methods using hot air or electromagnetic waves, depending on the electrode material of the battery body 20. Any type of electromagnetic wave suitable for heating is acceptable, including general infrared, microwave, and high-frequency heating. In this embodiment, the removed battery body 20 is placed in a firing furnace and heated by high-frequency induction heating using a high-frequency coil. In this case, since the case 11 is removed and the battery body 20 is heated, the energy consumption during heating is lower than in conventional methods. Alternatively, in heating step S50, the wound body 21 may be unwound from the battery body 20, and only the unwound wound body 21 may be heated. This is preferable because it allows for low-temperature and uniform heating. Unwinding refers to unwinding the wound body 21, transitioning from a roll to a sheet.

[0041] Next, in the crushing step S60, the heated coiled body 21 is crushed using, for example, a shear crusher and / or a high-speed hammer mill to obtain crushed material. Then, in the recovery step S70, the crushed material is sieved according to size using a known method, magnetically separated to obtain metal concentrates, and wet refining is performed to recover the desired valuable metals.

[0042] Conventionally, the roasting process involved roasting and crushing the entire outer casing, resulting in the problem of low purity of the valuable metals obtained. However, in this embodiment, the outer casing 10 is removed, thus increasing the purity of the valuable metals obtained. In this case, by performing initial fracture from the weakened section 14, the outer casing 10 can be fractured with a small external force, and therefore, according to the recycling method of this embodiment, the purity of the valuable metals can be easily improved.

[0043] (Embodiment 2) Another embodiment of the present invention is shown in Figure 8. In this embodiment, the grooves 13A and weakened portion 14A of the lithium-ion battery 1A are formed in a different shape from that of Embodiment 1, but all other aspects are the same. The same reference numerals are used for identical components as in Embodiment 1. In this embodiment, two grooves 13A are formed spaced apart on the side surface of the outer casing 10, extending along the outer circumference. The grooves 13A are close together and parallel to each other. In this embodiment, the grooves 13A are formed in a straight line, but they may also be curved. Between these grooves 13A, a weakened portion 14A is formed, connected to the two grooves 13A. The weakened portion 14A is provided in a circular shape on the side surface connected to the short side of the ceiling surface 12. In this embodiment as well, the weakened portion 14A is formed deeper than the grooves 13A.

[0044] In this embodiment, in the initial rupture step S33, the lithium-ion battery 1A is pressed near the weakened portion 14A on the side surface where the weakened portion 14A is formed, similar to Embodiment 1, to rupture the weakened portion 14A and form a hole that penetrates to the interior. Then, as shown in Figure 9, in the rupture step S34, the outer casing 10 is ruptured by peeling off the wall surface 15 of the outer casing 10 between the grooves 13A from the hole that penetrates to the interior formed by the initial rupture, along the grooves 13A. Thus, in this embodiment, it is possible to rupture the outer casing 10 starting from the weakened portion 14A in the rupture step S34. Furthermore, in this embodiment as well, by providing the weakened portion 14A, the outer casing 10 can be easily ruptured, and as a result, the heating process can be performed after removing the outer casing 10, and the purity of the valuable metals that are recycled can be easily improved. (modified version)

[0045] The present invention is not limited to the embodiments described above. For example, the structure of the weakening portion 14 is not limited to those described above, and may be in the shape shown in Figures 10(1) to (3), for example. Figures 10 and 11 are schematic diagrams showing parts of lithium-ion batteries 1B to 1F, and terminals and the like are omitted. In the lithium-ion battery 1B shown in Figure 10(1), the groove 13B is formed along the perimeter of the ceiling surface 12 of the outer casing 10, and the weakening portion 14B is also formed on the ceiling surface 12 along the groove 13B. In the lithium-ion battery 1C shown in Figure 10(2), the groove 13C is formed on the side surface of the outer casing 10 in the same way as in Embodiment 1, but the weakening portion 14C is formed on the ceiling surface 12. In the lithium-ion battery 1D shown in Figure 10(3), the groove 13D is formed on the outer circumference of the side surface of the outer casing 10, and the weakening portion 14D is formed in a circular ring shape connected to the groove 13D on the side surface that is continuous with the long side of the ceiling surface. In the weakened portion 14D, when the internal pressure of the outer casing 10 is increased by heating or pressing the outer casing 10 to cause initial fracture, it is preferable that the weakened portion 14D be formed on a side continuous with the long side of the ceiling surface 12, as this increases the deformation during initial fracture. Other shapes for the weakened portion 14D, such as an "X" shape, are also possible. In addition, in Figures 10(1) to (3), the grooves 13B to 13D may be provided in a curved shape. In any of these cases, the outer casing 10 can be easily fractured by performing initial fracture of the weakened portion 14B to 14D in the initial fracture step S33, and then performing fracture of the grooves 13B to 13D starting from there in the fracture step S34.

[0046] Furthermore, even when multiple grooves 13A are formed as in Embodiment 2, the structure of the weakened portion 14A is not limited to the one described above, and may have a shape as shown in Figures 11(1) and (2), for example. In Figure 11(1), the weakened portion 14E formed between two grooves 13E is connected to the two grooves 13E, but its shape is linear. Alternatively, as shown in Figure 11(2), the weakened portion 14F may be formed at the corner of the outer casing 10 while being connected to the two grooves 13F. In any of these cases, the outer casing 10 can be easily broken by performing initial breakage of the weakened portions 14E and 14F in the initial breakage step S33, and then breaking the grooves 13E and 13F starting from that point in the breakage step S34.

[0047] In this embodiment, the groove forming step S31 and the weakened portion forming step S32 were performed separately, but the embodiment is not limited to this. They may be performed simultaneously, that is, the groove 13 may be formed while the weakened portion 14 is formed, or the weakened portion forming step S32 may be performed first, followed by the groove forming step S31.

[0048] In the embodiments 1 and 2 described above, a weakening portion forming step S32 for forming the weakened portion 14 is provided, but the invention is not limited thereto. For example, if a used lithium-ion battery 1 is already deformed and has a recess or scratches when it is recovered, these recesses or scratches may be used as weakened portions 14 to 14F without forming the weakened portions 14 to 14F.

[0049] Furthermore, the weakened portions 14-14F may be partially formed in the outer casing 10 beforehand. For example, as shown in Figure 12(1), a thin-walled portion 16 that does not affect the safety of the lithium-ion battery 1 may be formed in advance during the manufacturing of the outer casing 10, and then, after being collected as waste, one or more grooves as weakened portions 14G may be formed in the thin-walled portion 16 as shown in Figure 12(2). In this modified example, an annular weakened portion 14G is formed in the thin-walled portion 16 when viewed from the front. In this case, stress is concentrated in the weakened portion 14G, making it prone to fracture.

[0050] Furthermore, when the weakened portion 14 initially ruptures due to an increase in the internal pressure of the outer casing 10, and when a safety valve is provided in the lithium-ion battery 1, it is preferable that the weakened portion 14 is formed to rupture at a pressure that does not activate the safety valve. That is, it is preferable that the rupture strength of the weakened portion 14 is less than the rupture strength of the groove 13 and also less than the rupture strength of the safety valve. Since the operating pressure of such a safety valve is usually 1.5 MPa or higher, it is formed to be less than 1.5 MPa. Also, when a safety valve is provided in the lithium-ion battery 1 during manufacturing, the safety valve may be made to function as the weakened portion 14. In this case, forming the groove 13 near the safety valve makes it easier to rupture the entire outer casing 10.

[0051] In embodiments 1 and 2 described above, the weakened parts 14 and 14A were fractured in the initial fracture process, but the method of initial fracture is not limited to this. For example, it is also possible to corrode the outer casing 10 by applying a chemical solution to cause initial fracture. In this case, the chemical solution depends on the metal that makes up the outer casing 10, but if the outer casing 10 is made of aluminum, examples of acidic chemical solutions include strong acids such as hydrochloric acid, and weak acids such as phosphoric acid, hydrofluoric acid, acetic acid, and citric acid. Examples of basic chemical solutions include strong bases such as hydroxides of alkali metals and alkaline earth metals (specifically NaOH, KOH, Ca(OH)2, etc.), and weak bases such as sodium hypochlorite, hypochlorites made of alkali metals and alkaline earth metals, ammonia water, and primary, secondary, and tertiary amines can also be used. It is also effective to perform initial fracture while heating the chemical solution or aluminum substrate for purposes such as accelerating the corrosion reaction. Methods for applying the chemical solution to the weakened area include spraying it from a nozzle, applying it with a brush, or applying a cloth or tape impregnated with the chemical solution.

[0052] In the embodiment described above, a heating step S50 was performed after the battery dismantling step S30. However, it is also possible to dismantle the battery directly without going through the heating step, perform the crushing step S60 and the recovery step S70, sieve the crushed material according to size, perform magnetic separation to obtain a metal concentrate, and recover the desired valuable metal by wet refining. [Explanation of symbols]

[0053] 1. Lithium-ion battery 10 Exterior 11 cases 12 Ceiling surface 13 Groove 14 Weakened part 15 Wall surface 16 Thin-walled section 20 Battery Unit 21 Wound body 30 terminals P1 Holding fixture P2 Pressing jig R1 area S10 Discharge process S20 Pack Disassembly Process S30 battery disassembly process S31 Groove formation process S32 Weakened part formation process S33 Initial fracture process S34 Fracture process S35 Extraction process S40 Exterior Assembly Recovery Process S50 heating process S60 Grinding Process S70 Recovery Process

Claims

1. A method for recycling a battery comprising an outer casing and a battery body housed within the outer casing, A groove forming step in which grooves are formed in the outer casing for breaking the outer casing, An initial fracture step in which initial fracture is performed at the weakened portion formed in the exterior body. A battery recycling method comprising a breaking step of breaking the outer casing at the groove via the broken weakened portion, wherein the battery body is removed from the outer casing and the battery is recycled.

2. The battery recycling method according to claim 1, characterized in that the thickness of the outer casing in the portion where the weakened portion is formed is thinner than the thickness of the outer casing in the portion where the groove is formed.

3. The battery recycling method according to claim 1, further comprising a weakening portion forming step for forming the weakened portion on the outer casing.

4. The battery recycling method according to claim 1, characterized in that the groove is formed so that the groove and the weakened portion are continuous.

5. The battery recycling method according to claim 1, characterized in that the initial rupture step involves pressing the vicinity of the weakened portion of the outer casing to perform the initial rupture of the weakened portion.

6. The battery recycling method according to claim 1, characterized in that the initial rupture step involves pressing the outer casing to increase its internal pressure, thereby causing the initial rupture of the weakened portion.

7. The battery recycling method according to claim 1, characterized in that the initial rupture step is performed by applying a chemical solution to the weakened portion to cause the initial rupture of the weakened portion.

8. The battery recycling method according to claim 1, characterized in that the initial rupture step involves heating the outer casing to increase its internal pressure, thereby causing the initial rupture of the weakened portion.

9. The battery recycling method according to claim 1, characterized in that the initial rupture step is performed by cutting the weakened portion of the outer casing.

10. The battery recycling method according to claim 1, further comprising a heating step of heating the removed battery body.

11. The battery recycling method according to claim 10, characterized in that, in the heating step, the winding body consisting of electrodes and separators constituting the battery body is unwound before heating.

12. The battery recycling method according to any one of claims 1 to 11, characterized in that the battery has a negative electrode terminal and a positive electrode terminal on one ceiling surface constituting the outer casing, and the weakened portion and the groove are formed on a side surface continuous with the ceiling surface.

13. In the groove forming step, two grooves are formed on the side surface of the exterior body. The battery recycling method according to claim 1, characterized in that in the initial rupture step, the initial rupture is performed at the weakened portion connected to either of the two grooves, and thereafter, in the rupture step, the wall surface of the outer casing between the grooves is peeled off and ruptured along the grooves.

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