This application claims the benefit of priority to Japanese Patent Application No. 2022-113651 filed on Jul. 15, 2022. The entire contents of this application are hereby incorporated herein by reference.
The present application relates to lithium ion battery processing methods.
To effectively utilize resources by reducing waste, conventional technologies involve collecting used lithium ion batteries so as to recycle battery materials. Prior art documents related to such technologies include, for example, JP 2020-198320 A, Japanese Patent No. 6828214, and JP 6-251805 A. These documents disclose forcedly discharging a lithium ion battery before disassembling the lithium ion battery so as to prevent ignition caused by a short circuit between positive and negative electrodes during disassembling. JP 2020-198320 A discloses a technique involving: cutting an exterior body of a lithium ion battery with, for example, a tool (such as an end mill) or laser after a discharging process; removing an electrode body from the exterior body; and collecting valuable metals, such as nickel (Ni) and cobalt (Co), which are recyclable resources.
Findings obtained by the inventor of the present application, however, suggest that lithium ion batteries collected usually vary in state of charge (SOC). Variations in SOC unfortunately complicate the operation of a discharging process, leading to an increase in cost. If lithium ion batteries are temporarily discharged to 0 V, letting the lithium ion batteries stand for a while may increase the voltages thereof, making it difficult to completely discharge the lithium ion batteries to 0 V. Lithium ion batteries collected may include ones that are unusable because of, for example, overcharge or overdischarge. In this case, a safety device is usually activated, which may make it impossible to perform a discharging process. Cutting a lithium ion battery having a voltage with a tool or laser as described in JP 2020-198320 A and Japanese Patent No. 6828214 may cause a short circuit between positive and negative electrodes, which may result in ignition. This requires strict safety measures (such as preparing a fire extinguishing system in advance) in performing the cutting operation.
Accordingly, embodiments of the present application provide lithium ion battery processing methods that are simpler and safter than ever before.
An embodiment of the present application provides a lithium ion battery processing method including a collecting step and a cutting step. The collecting step involves collecting a lithium ion battery including: an electrode body; a battery case including an opening and housing the electrode body; a lid closing the opening of the battery case; and an electrode terminal connected to the electrode body inside the battery case and partially exposed to outside of the battery case. The cutting step involves cutting a connection between the electrode terminal and the electrode body of the collected lithium ion battery by using a water jet cutter. The processing method includes no lithium ion battery discharging step between the collecting step and the cutting step.
The water jet cutter pressurizes a fluid, such as water, and ejects the fluid at high pressure to a cutting target so as to cut the cutting target. The cutting step involves using the water jet cutter. This makes it possible to not only cut the cutting target (which is the lithium ion battery in this embodiment) without being affected by heat, but also achieve cooling effect, which reduces or prevents the risk of ignition. The use of the water jet cutter also leads to improved safety. Accordingly, this embodiment eliminates the need to discharge the lithium ion battery in advance, making it possible to process the lithium ion battery more easily than before. The water jet cutter usually includes a table which is disposed in a water tank and on which the cutting target is to be placed. Consequently, in the event that the lithium ion battery is ignited during the cutting step, the lithium ion battery is immersed in water in the water tank, which extinguishes a fire in the lithium ion battery. This eliminates the need to additionally prepare a fire extinguishing system, resulting in a reduction in the burden of advance preparations.
The above and other elements, features, steps, characteristics, and advantages of the present application will become more apparent from the following detailed description of the preferred embodiments with reference to the attached drawings.
Preferred embodiments of processing methods disclosed herein will be described below with reference to the drawings. Matters that are necessary for carrying out the present application but are not specifically mentioned herein may be understood by those skilled in the art as design matters based on techniques known in the related art. The present application may be carried out on the basis of the description given herein and common technical knowledge in the related art.
As used herein, the term “battery” refers to any of various electricity storage devices from which electric energy is derivable, and is a concept encompassing primary batteries and secondary batteries. As used herein, the term “secondary battery” refers to any of various electricity storage devices that are repeatedly chargeable and dischargeable, and is a concept encompassing not only storage batteries (or chemical batteries), such as lithium ion secondary batteries, but also lithium ion capacitors (or physical batteries).
Structure of Battery 100
As illustrated in
As illustrated in
The positive electrode 12 includes a positive electrode collector 12c and a positive electrode composite layer 12a fixed onto the positive electrode collector 12c. The positive electrode collector 12c is made of, for example, a conductive metal, such as aluminum, an aluminum alloy, nickel, or stainless steel. In the present embodiment, the positive electrode collector 12c is made of aluminum. The positive electrode composite layer 12a typically includes: a positive electrode active material that is able to reversibly store and discharge charge carriers (e.g., a lithium transition metal composite oxide); and a binder (e.g., polyvinylidene fluoride (PVDF)).
The negative electrode 14 includes a negative electrode collector 14c and a negative electrode composite layer 14a fixed onto the negative electrode collector 14c. The negative electrode collector 14c is made of, for example, a conductive metal, such as copper, a copper alloy, nickel, or stainless steel. In the present embodiment, the negative electrode collector 14c is made of copper. The negative electrode composite layer 14a typically includes: a negative electrode active material that is able to reversibly store and discharge charge carriers (e.g., a carbon material, such as graphite); and a binder (e.g., styrene-butadiene rubber (SBR) or carboxymethylcellulose (CMC)).
A portion (or a positive electrode tab) of the positive electrode collector 12c provided with no positive electrode composite layer 12a is exposed at an upper end of the positive electrode 12. A positive electrode lead member 13 is attached to the positive electrode tab. The positive electrode lead member 13 extends along an inner surface of the exterior body 20. The positive electrode lead member 13 may be made of the same metal material as the positive electrode collector 12c. The positive electrode lead member 13 may be made of, for example, a conductive metal, such as aluminum, an aluminum alloy, nickel, or stainless steel. A portion (or a negative electrode tab) of the negative electrode collector 14c provided with no negative electrode composite layer 14a is exposed at an upper end of the negative electrode 14. A negative electrode lead member 15 is attached to the negative electrode tab. The negative electrode lead member 15 extends along the inner surface of the exterior body 20. The negative electrode lead member 15 may be made of the same metal material as the negative electrode collector 14c. The negative electrode lead member 15 may be made of, for example, a conductive metal, such as copper, a copper alloy, nickel, or stainless steel.
The electrolytic solution is, for example, a nonaqueous liquid electrolyte (or a nonaqueous electrolytic solution) containing a nonaqueous solvent and a lithium salt (or a supporting electrolyte). Examples of the nonaqueous solvent include carbonates, such as ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC). Examples of the supporting electrolyte include a fluorine-containing lithium salt, such as lithium hexafluorophosphate (LiPF6).
As illustrated in
The battery case 22 is a casing housing the electrode body 10 and storing the electrolytic solution. The battery case 22 includes the opening 22h and a bottom wall 22d facing the opening 22h. The opening 22h and the bottom wall 22d of the battery case 22 each have a substantially rectangular shape. As used herein, the term “substantially rectangular shape” refers to not only a perfect rectangular shape (or a perfect oblong shape) but also various other rectangular shapes, such as a rectangular shape whose corners connecting long and short sides are rounded and a rectangular shape whose corners have cut-outs.
The lid 24 is a plate member closing the opening 22h of the battery case 22. The lid 24 has a substantially rectangular shape. The lid 24 is fitted to the opening 22h of the battery case 22 such that the lid 24 faces the bottom wall 22d. Ends of the lid 24 in the long-side direction X are each provided with a through hole 24h. The through hole 24h located on a first side in the long-side direction X (i.e., the left side in
The positive electrode terminal 30 and the negative electrode terminal 40 are each inserted through the associated through hole 24h and extend from inside to outside of the exterior body 20. The positive electrode terminal 30 may hereinafter be referred to as an “electrode terminal 30”. The negative electrode terminal 40 may hereinafter be referred to as an “electrode terminal 40”. The electrode terminals 30 and 40 are each disposed on an associated one of the ends of the lid 24 in the long-side direction X. In the present embodiment, the electrode terminals 30 and 40 are attached to the same surface (or specifically, the lid 24) of the exterior body 20. The electrode terminals 30 and 40 are swaged to portions of the lid 24 surrounding peripheral edges of the through holes 24h. Lower ends of the electrode terminals 30 and 40 are respectively provided with rivet portions 30c and 40c.
The positive electrode terminal 30 is electrically connected to the positive electrode 12 of the electrode body 10 through the positive electrode lead member 13 inside the battery case 22. The positive electrode terminal 30 is made of, for example, metal, such as aluminum, an aluminum alloy, nickel, or stainless steel. The positive electrode terminal 30 may be made of the same metal material as the positive electrode collector 12c. In the present embodiment, the positive electrode terminal 30 is made of aluminum. The negative electrode terminal 40 is electrically connected to the negative electrode 14 of the electrode body 10 through the negative electrode lead member 15 inside the battery case 22. The negative electrode terminal 40 is made of, for example, metal, such as copper, a copper alloy, nickel, or stainless steel. The negative electrode terminal 40 may be made of the same metal material as the negative electrode collector 14c. In the present embodiment, the negative electrode terminal 40 is made of copper.
The electrode terminal 30 is insulated from the lid 24 with a gasket 50 and an insulator 60 interposed therebetween. The electrode terminal 40 is insulated from the lid 24 with another gasket 50 and another insulator 60 interposed therebetween. The gaskets 50 are insulating members disposed between an upper surface (or outer surface) of the lid 24 and the electrode terminals 30 and 40. In the present embodiment, the gaskets 50 have the functions of insulating the lid 24 from the electrode terminals 30 and 40 and closing the through holes 24h. The insulators 60 are insulating members disposed between a lower surface (or inner surface) of the lid 24 and the lead members 13 and 15. The gaskets 50 and the insulators 60 are each made of an electrically insulating, elastically deformable resin material that is resistant to the electrolyte to be used. Examples of the resin material include: fluorinated resin, such as perfluoro alkoxy alkane (PFA); and polyphenylene sulfide (PPS).
The positive electrode terminal 30 is electrically connected to a plate-shaped positive electrode external conductive member 32 above the upper surface of the lid 24. The negative electrode terminal 40 is electrically connected to a plate-shaped negative electrode external conductive member 42 above the upper surface of the lid 24. The positive electrode external conductive member 32 and the negative electrode external conductive member 42 are each connected to another secondary battery and/or an external device through, for example, a busbar. The positive electrode external conductive member 32 and the negative electrode external conductive member 42 are insulated from the lid 24 with external insulating members 70. The positive electrode external conductive member 32 and the negative electrode external conductive member 42, however, may be optional.
The positive electrode external conductive member 32 and the negative electrode external conductive member 42 are each preferably made of a highly conductive metal. The positive electrode external conductive member 32 and the negative electrode external conductive member 42 are each made of, for example, aluminum, an aluminum alloy, copper, or a copper alloy. The positive electrode external conductive member 32 may be made of the same metal material as the positive electrode terminal 30. In the present embodiment, the positive electrode external conductive member 32 is made of aluminum. The negative electrode external conductive member 42 may be made of the same metal material as the negative electrode terminal 40. In the present embodiment, the negative electrode external conductive member 42 is made of copper.
Method for Processing Battery 100
The battery collecting step (step S0) involves collecting the batteries 100. The batteries 100 each typically have a voltage. The batteries 100 may be unused. The batteries 100 may be unusable because of, for example, overcharge or overdischarge and may be unable to be discharged. In the present embodiment, the batteries 100 are collected in the form of the battery pack 200.
As illustrated in
As illustrated in
As used herein, the term “water jet cutter” refers to any of various apparatuses that cut a cutting target by using high-pressure energy from a thin stream of high-speed and high-density water (hereinafter referred to as a “water jet WJ”), and is a concept encompassing water jet cutting that involves cutting a cutting target with only a fluid (such as water) and abrasive jet cutting that involves cutting a cutting target with a fluid (such as water) mixed with an abrasive. A fluid to be used to cut a cutting target is typically water. Alternatively, a fluid other than water, such as a nonaqueous solvent to be used as the electrolytic solution for the battery 100, may be used to cut a cutting target. Any water jet cutter known in the art may be used. One example of a water jet cutter known in the art is an abrasive jet cutter available from Sugino
Machine Limited.
The water jet cutter 300 ejects a mixture of a fluid and an abrasive (i.e., the water jet WJ) from a cutting head 330 while moving the cutting head 330 relative to a cutting target. The water jet cutter 300 thus cuts the cutting target. The cutting target may have any shape. The cutting target may be made of any material. In the present embodiment, the cutting target is the battery 100. As illustrated in
The table 320 supports the cutting target (i.e., the battery 100). The table 320 is disposed in the water tank 310. The table 320 is secured to an inner surface of the water tank 310. Water is stored in the water tank 310. The water level of the water tank 310 is typically substantially on the same level as an upper surface of the table 320. The table 320 is in the form of a drainboard. The table 320 is disposed below the cutting head 330. The table 320 is smaller than the water tank 310 in a plan view. A portion of the water surface of the water tank 310 is occupied not by the table 320 but by a water tank opening 312. The water tank opening 312 is larger in outer shape than the battery 100. The water tank opening 312 is a space in which the battery 100 is to be immersed in water in the water tank 310 when the battery 100 is ignited.
The cutting head 330 is provided at its lower end with a nozzle 331. The cutting head 330 ejects the water jet WJ from the nozzle 331 to the battery 100 so as to cut the battery 100 placed on the table 320. The nozzle 331 typically has a diameter ϕ of between about 0.01 mm and about 0.5 mm (e.g., 0.1 mm). The cutting head 330 is retained by the carriage 340. The cutting head 330 is electrically connected to the controller (not illustrated). The controller controls ejection of the water jet WJ from the cutting head 330.
The high-pressure water feeder 332 is connected to an upper end of the cutting head 330 through a fluid feeding passage 333. The fluid feeding passage 333 may be made of any suitable material. The fluid feeding passage 333 is, for example, an easily deformable resin tube. The high-pressure water feeder 332 pressurizes a fluid (which is water in the present embodiment) and feeds a high-pressure energy water stream to the cutting head 330. The abrasive feeder 334 is connected to a lower end of the cutting head 330 through an abrasive feeding passage 335. The abrasive feeding passage 335 may be made of any suitable material. The abrasive feeding passage 335 is, for example, an easily deformable resin tube. The abrasive feeder 334 feeds an abrasive to high-pressure water. The pressure of the water jet WJ is suitably changeable in accordance with, for example, the material and thickness of the exterior body 20 and the diameter the nozzle 331. The pressure of the water jet WJ may be any suitable pressure. The pressure of the water jet WJ is typically between 200 MPa and 600 MPa. The pressure of the water jet WJ is preferably 300 MPa or more. The pressure of the water jet WJ is, for example, 600 MPa (which is equivalent to about 6000 atm).
The carriage 340 is equipped with the cutting head 330. The carriage 340 is movable at least in the right-left direction X1 and the front-rear direction Y1 by the conveyor 350. The carriage 340 is electrically connected to the controller (not illustrated). The controller controls movement of the carriage 340 in the right-left direction X1 and the front-rear direction Y1. The conveyor 350 includes: a first conveyor to move the carriage 340 and the cutting head 330 in the right-left direction X1; and a second conveyor to move the carriage 340 and the cutting head 330 in the front-rear direction Y1.
The first conveyor includes: a traverse gutter 352 extending in the right-left direction X1; and a guide shaft 354 disposed inside the traverse gutter 352. The carriage 340 is in slidable engagement with the guide shaft 354. The second conveyor includes: a pair of rails (not illustrated) disposed along the right and left ends of the water tank 310 and extending in the front-rear direction Y1; and a portal platform 356 provided with the traverse gutter 352 and configured to travel along the rails. The conveyor 350 moves the carriage 340 in the right-left direction X1 along the guide shaft 354, and moves the platform 356 in the front-rear direction Y1 along the rails. The conveyor 350 is thus able to move the cutting head 330 in desired directions within the horizontal plane of the table 320. In the course of movement of the cutting head 330, the cutting head 330 is brought into operation and ejects the water jet WJ to the battery 100 placed on the table 320 so as to cut the battery 100.
The hole making step (step S2) preferably involves making the holes h (through which the electrolytic solution is to be discharged) in portions of the battery case 22 located away from the positive electrode terminal 30 and the negative electrode terminal 40. In one example, the hole making step (step S2) preferably involves making the holes h in the bottom wall 22d as illustrated in
The electrolytic solution sucking step (step S3) involves discharging the electrolytic solution remaining in the exterior body 20. As illustrated in
The lid separating step (step S4) involves cutting a connection between the electrode body 10 and the electrode terminals 30 and 40 by using the water jet cutter 300 as illustrated in
In the present embodiment, the battery 100 is placed sideways on the table 320 of the water jet cutter 300, and the water jet cutter 300 ejects the water jet WJ along the boundary between the battery case 22 and the lid 24. The water jet cutter 300 is thus able to cut the exterior body 20, a positive electrode tab portion of the positive electrode collector 12c, and a negative electrode tab portion of the negative electrode collector 14c along the virtual line (or chain double-dashed line) C in
In the event that the battery 100 is ignited during the lid separating step (step S4), the battery 100 is slid from the upper surface of the table 320 to the water tank opening 312 and immersed in water in the water tank 310, which extinguishes a fire in the battery 100. This eliminates the need to additionally prepare a fire extinguishing system, resulting in a reduction in the burden of advance preparations. Thus, the lid 24 is separated from the electrode body 10 and the battery case 22, and an opening 22o larger than the electrode body 10 when viewed in cross section is formed in the battery case 22. After step S4, the process proceeds to step S5.
As illustrated in
As illustrated in
As illustrated in
As illustrated in
The method involving using ultrasonic waves is performed by, for example, placing the positive electrode 12 in an ultrasonic tank such that the positive electrode 12 is immersed in a liquid, such as a nonaqueous solvent, and then vibrating the liquid. This peels the positive electrode composite 12a from the positive electrode collector 12c. The method involving using a jet stream is performed by applying energy, such as a water jet stream, a vapor jet stream, or an air jet stream, to the positive electrode 12 for which adhesiveness of the binder is reduced by, for example, heat, and crushing the positive electrode composite 12a with the energy. The positive electrode collector 12c is thus separated from the positive electrode composite 12a. The positive electrode composite 12a separated is centrifuged and dried, so that the positive electrode composite 12a is turned into powder.
The positive electrode composite 12a in powder form contains valuable metals. The positive electrode composite 12a in powder form contains, in particular, rare metals, such as lithium (Li) and a transition metal (e.g., Ni, Co, or Mn). Rare metals may be collected from the positive electrode composite 12a by any method known in the art. In one example, the positive electrode composite 12a is dissolved in acid and is then subjected to electrodialysis or pH adjustment, so that Li and Co are precipitated in the form of hydroxides. The hydroxides are filtered, washed with water, dried, and fired, with the result that rare metals are separated and collected in the form of oxides. Performing this method makes it more unlikely that intrusion of components of the exterior body 20, such as aluminum and copper, will occur and rare metals of higher purity are separated and collected than when a battery is cut into small pieces as described in, for example, Japanese Patent No. 6828214. As described thus far, the processing method disclosed herein may also be regarded as a method for collecting valuable metals (or in particular, rare metals).
Although the preferred embodiment of the present application has been described thus far, the foregoing embodiment is only illustrative, and the present application may be embodied in various other forms. The present application may be practiced based on the disclosure of this specification and technical common knowledge in the related field. The techniques described in the claims include various changes and modifications made to the embodiment illustrated above. Any or some of the technical features of the foregoing embodiment, for example, may be replaced with any or some of the technical features of variations of the foregoing embodiment. Any or some of the technical features of the variations may be added to the technical features of the foregoing embodiment. Unless described as being essential, the technical feature(s) may be optional.
Variation 1
As illustrated in
Variation 2
The hole making step (step S2) and the lid separating step (step S4) according to the foregoing embodiment involve using the water jet cutter 300 that ejects high-pressure water as illustrated in
Variation 3
As illustrated in
As described above, specific embodiments of the techniques disclosed herein include those described in clauses below.
Clause 1: A lithium ion battery processing method including a collecting step and a cutting step, the collecting step involving collecting a lithium ion battery including: an electrode body; a battery case including an opening and housing the electrode body; a lid closing the opening of the battery case; and an electrode terminal connected to the electrode body inside the battery case and partially exposed to outside of the battery case, the cutting step involving cutting a connection between the electrode terminal and the electrode body of the collected lithium ion battery by using a water jet cutter, wherein the processing method includes no lithium ion battery discharging step between the collecting step and the cutting step.
Clause 2: The processing method according to clause 1, wherein the cutting step involves cutting the lithium ion battery having a voltage.
Clause 3: The processing method according to clause 1 or 2, wherein the electrode terminal is attached to the lid, and the cutting step involves separating the lid from the electrode body and the battery case.
Clause 4: The processing method according to clause 3, wherein the lid and the electrode terminal are made of different materials, and the processing method further includes a terminal separating step involving separating the electrode terminal from the lid after the cutting step.
Clause 5: The processing method according to any one of clauses 1 to 4, wherein the lithium ion battery collected includes an electrolytic solution, and the processing method further includes: a hole making step involving, before the cutting step, making a hole in the battery case by using the water jet cutter; and an electrolytic solution sucking step involving sucking the electrolytic solution through the hole.
Clause 6: The processing method according to claim 5, further including an electrode body removing step involving, after the electrolytic solution sucking step and the cutting step, inserting a pushing rod through the hole so as to push the electrode body out of the opening of the battery case.
Clause 7: The processing method according to any one of clauses 1 to 6, wherein the lithium ion battery includes a solvent, the water jet cutter includes a cutting head to eject a fluid, and the cutting head is configured to eject the solvent collected from the lithium ion battery.
Although the preferred embodiment of the present application has been described thus far, the foregoing embodiment is only illustrative, and the present application may be embodied in various other forms. The present application may be practiced based on the disclosure of this specification and technical common knowledge in the related field. The techniques described in the claims include various changes and modifications made to the embodiment illustrated above. Any or some of the technical features of the foregoing embodiment, for example, may be replaced with any or some of the technical features of variations of the foregoing embodiment. Any or some of the technical features of the variations may be added to the technical features of the foregoing embodiment. Unless described as being essential, the technical feature(s) may be optional.
Number | Date | Country | Kind |
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2022-113651 | Jul 2022 | JP | national |