Power storage module and method for detaching power storage module

Abstract

The invention provides a power storage module and a method for detaching the power storage module, wherein the power storage module can be easily detached while suppressing the increase of steps during recycling and the like. A power storage module is provided with bipolar electrodes provided with a positive electrode active material on one surface of a current collector foil and a negative electrode active material on the other surface of the current collector foil, an electrode laminate in which a plurality of bipolar electrodes are laminated, and a resin sealing part provided at the peripheral edge of the current collector foil, and a sealing portion that seals between the bipolar electrodes adjacent to each other in the lamination direction of the electrode laminate, the sealing portion having a recessed portion that forms a gap between the peripheral edge portions of the collector foils adjacent to each other in the lamination direction.

Description

Technical Field

[0001] This invention relates to a battery storage module and a method for disassembling the battery storage module. Background Technology

[0002] Japanese Patent Application Publication No. 2022-114963 discloses a method for disassembling an energy storage module, which involves separating the bipolar electrodes by disassembling the module and then cooling the bipolar electrodes as a whole to separate the current collector, substrate, and adhesive. In the solution described in Japanese Patent Application Publication No. 2022-114963, the cooling temperature of the bipolar electrodes is set to the temperature at which the current collector and substrate peel off from the adhesive due to the difference in their coefficients of linear expansion. Summary of the Invention

[0003] During the recycling of the energy storage module, the unit is disassembled to recover the electrolyte and bipolar electrodes inside. At this time, it is considered to remove the resin seal that forms the outer frame of the energy storage module to open the unit. In this case, if the portion of the energy storage module inside the outer frame is cut off by cutting off the seal, the periphery of the current collector foil will also be cut off, and the cut piece includes a portion of the current collector foil. To recover the current collector foil from this cut piece, combustion and separation are required, increasing the number of processes.

[0004] The present invention was made in view of the above circumstances, and its object is to provide an energy storage module and a method for disassembling the energy storage module that can suppress the increase of processes during recycling and can be easily disassembled.

[0005] The energy storage module of the present invention is characterized by comprising a bipolar electrode, an electrode stack, and a resin sealing portion. The bipolar electrode has a positive active material disposed on one side of the current collector foil and a negative active material disposed on the other side of the current collector foil. The electrode stack is formed by stacking multiple bipolar electrodes. The resin sealing portion is disposed at the periphery of the current collector foil and seals adjacent bipolar electrodes in the stacking direction of the electrode stack. The sealing portion has a recess that forms a gap between the peripheries of adjacent current collector foils in the stacking direction.

[0006] In this invention, the increase in processes can be suppressed during recycling and disassembly can be easily performed. Attached Figure Description

[0007] Hereinafter, the features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described with reference to the accompanying drawings, wherein like reference numerals denote like elements.

[0008] Figure 1 This is an external view of the energy storage module in the implementation method.

[0009] Figure 2It is a cross-sectional view showing the structure formed by stacking current collector foil and sealing part.

[0010] Figure 3 This is a diagram used to illustrate the components that make up an energy storage module.

[0011] Figure 4 It is a diagram showing the uneven shape of the sealant film.

[0012] Figure 5 This is a flowchart illustrating the disassembly method of the energy storage module.

[0013] Figure 6 This diagram illustrates the state of cracks forming in the sealing part.

[0014] Figure 7 This diagram illustrates the state in which the resin in the sealing section is crushed during cooling and pressing.

[0015] Figure 8 This is a diagram illustrating an example of the cooling and disassembly process. Detailed Implementation

[0016] The following describes in detail the energy storage module and the method for disassembling the energy storage module in the embodiments of the present invention. Furthermore, the present invention is not limited to the embodiments described below.

[0017] Figure 1 This diagram illustrates the energy storage module in the embodiment. The energy storage module 1 is used as a battery in vehicles such as plug-in hybrid electric vehicles and electric vehicles. The energy storage module 1 is a lithium-ion battery, constituting a bipolar battery. The bipolar battery is a battery pack composed of multiple energy storage modules 1 stacked together. The bipolar battery containing the energy storage module 1 is a bipolar lithium-ion battery.

[0018] The energy storage module 1 has a structure formed by stacking multiple units. The energy storage module 1 includes: an electrode stack 2 formed by stacking multiple electrodes; and a sealing part 3 for sealing the electrode stack 2. The sealing part 3 is formed in the frame that forms the outer frame of the energy storage module 1.

[0019] The electrode stack 2 has a structure consisting of multiple bipolar electrodes, a positive terminal electrode, a negative terminal electrode, and multiple separators stacked together. Each bipolar electrode includes a current-collecting foil 10, a positive active material, and a negative active material. In the bipolar electrode, a positive active material is provided on one side of the current-collecting foil 10, and a negative active material is provided on the other side. The positive terminal electrode includes a terminal positive electrode foil and a terminal positive active material disposed on one side of the terminal positive electrode foil. The negative terminal electrode includes a terminal negative electrode foil and a terminal negative active material disposed on one side of the terminal negative electrode foil. Between the positive and negative terminal electrodes, bipolar electrodes and separators are alternately stacked. In the stacking direction, adjacent bipolar electrodes are stacked with the positive active material of one bipolar electrode and the negative active material of the other bipolar electrode sandwiched by a separator.

[0020] like Figure 2 As shown, the current collector foil 10 is a current collector formed by bonding aluminum foil 11 and copper foil 12 together via an adhesive layer 13. That is, the current collector foil 10 is a bonding foil. Aluminum foil 11 is the positive electrode substrate (positive electrode foil). Copper foil 12 is the negative electrode substrate (negative electrode foil). Adhesive layer 13 is a resin layer that bonds the aluminum foil 11 and copper foil 12 together. Adhesive layer 13 contains epoxy resin.

[0021] One side of the aluminum foil 11 is bonded to the copper foil 12 via an adhesive layer 13. A positive electrode active material is disposed on the other side of the aluminum foil 11. The positive electrode active material is smaller in shape than the aluminum foil 11. The other side of the aluminum foil 11 includes an uncoated portion. This uncoated portion is the area where no positive electrode active material is disposed, located at the periphery of the aluminum foil 11. The periphery of the aluminum foil 11 is the periphery of the current collector foil 10.

[0022] One side of the copper foil 12 is bonded to the aluminum foil 11 via an adhesive layer 13. A negative electrode active material is disposed on the other side of the copper foil 12. The negative electrode active material is smaller in shape than the copper foil 12. The other side of the copper foil 12 includes an uncoated portion. This uncoated portion is the area where no negative electrode active material is disposed, located at the periphery of the copper foil 12. The periphery of the copper foil 12 is the periphery of the current collector foil 10.

[0023] The unit comprises an electrode stack 2, a sealing portion 3, and an electrolyte. Adjacent units in the stacking direction share a single bipolar electrode and are electrically connected in series via this bipolar electrode. The electrolyte is contained within a space defined by adjacent current collector foils 10 in the stacking direction and the sealing portion 3 located between the current collector foils 10. Additionally, the electrolyte is contained within a space defined by the bipolar electrode, the positive terminal electrode, and the sealing portion 3 located between them. Similarly, the electrolyte is contained within a space defined by the bipolar electrode, the negative terminal electrode, and the sealing portion 3 located between them.

[0024] The sealing part 3 is disposed at the periphery of the current collector foil 10 and is a sealing member configured to not contact the positive electrode active material and the negative electrode active material. The sealing part 3 is made of insulating resin. The material constituting the sealing part 3 can be resin materials such as polypropylene (PP), polyethylene (PE), polyphenylene sulfide (PPS), polystyrene (PS), ABS resin, and AS resin. For example, the sealing part 3 is made of a composite of polypropylene, polyethylene, and polyphenylene sulfide.

[0025] The energy storage module 1 has a structure in which the peripheral portion of the current collector foil 10 is laminated with multiple resins. That is, the sealing portion 3 is composed of multiple sealing members. Furthermore, as... Figure 2 As shown, the sealing part 3 has a recess 4 in which the peripheral portions of adjacent current collector foils 10 in the stacking direction form gaps between each other.

[0026] The recess 4 is formed in a recessed shape in the stacking direction, and multiple recesses 4 are provided in the sealing portion 3. Multiple recesses 4 are provided along the periphery of the current collector foil 10 at positions where they overlap with the periphery of the current collector foil 10. Multiple recesses 4 are provided throughout the entire circumference of the frame formed by the sealing portion 3.

[0027] The recess 4 is provided in at least one of the plurality of sealing members constituting the sealing portion 3. For example, the recess 4 is provided in the first sealing member among the plurality of sealing members that contacts the surface of the peripheral portion of the current collector foil 10. Figure 2 In the example shown, a recess 4 is provided in the first sealing member that contacts the aluminum foil 11. The recess 4 is provided on the surface of the first sealing member that contacts the peripheral portion of the aluminum foil 11.

[0028] The sealing portion 3 has the following structure: At the periphery of the current collector foil 10, a portion of the resin has irregularities (undulations). During cooling and pressing, stress concentrates in the recesses 4, making the resin prone to cracking. Because the sealing portion 3 includes the recesses 4, stress concentrates on the thinner portion of the resin during cooling and pressing, causing cracks to originate there, and the resin slips off. The portion laminated by heating is the outermost end of the current collector foil 10; the portion inward from this end does not transfer heat, leaving behind the irregularities. By leaving gaps in the sealing portion 3, the starting point for cracking during cooling and pressing can be ensured.

[0029] like Figure 3 As shown, in the energy storage module 1, multiple resins, such as seals and spacers, a sealant film 21, and a terminal housing, are provided on the periphery of the current collector foil 10, and these resins are fused together using a laminated film 22. The sealing part 3 includes a seal (first sealing member), a spacer, a sealant film 21, a terminal housing, and a laminated film 22.

[0030] The sealant film 21 is made of polypropylene resin. The sealant film 21 is arranged to cover the periphery of the current collector foil 10 on all four sides. For example... Figure 4As shown, one side of the sealant film 21 is formed in an uneven shape. The sealant film 21 includes an uneven surface 21b with a recess 21a and a flat surface 21c. It is possible to use a structure in which a portion of the sealant film 21 has an uneven shape.

[0031] The laminate 22 comprises polypropylene resin. The laminate 22 is fused to the sealant film 21. The laminate 22 is disposed on the outer side of the sealant film 21 in a direction orthogonal to the lamination direction.

[0032] Figure 5 This is a flowchart illustrating the disassembly method of the energy storage module. The disassembly method of the energy storage module 1 includes a harmless treatment process (step S1), a package disassembly process (step S2), a cooling disassembly process (step S3), and a recycling process (step S4).

[0033] The harmless treatment process is a process of safely discharging the battery pack (step S1). The harmless treatment process includes a discharge process of discharging the battery pack. The battery pack is a bipolar battery having multiple energy storage modules 1.

[0034] The battery pack disassembly process is the process of disassembling the battery pack and separating the energy storage modules 1 from the constituent components of the battery pack (step S2). This disassembly process disassembles the structure formed by stacking multiple energy storage modules 1 and separates the energy storage modules 1 on a unit basis.

[0035] The cooling and disassembly process is a process in which stress is applied to the sealing portion 3 while it is cooled, causing the sealing portion 3 to be crushed (step S3). The cooling and disassembly process cools and disassembles each battery module 1 in a manner that allows separation from each bipolar electrode. In the cooling and disassembly process, the battery module 1 is cooled, and the sealing portions 3 provided on the four sides of the battery module 1 are removed. The cooling and disassembly process includes: a cooling process for concentrated cooling of the sealing portions 3; a pressing process for applying stress to the sealing portions 3 in a cooled environment; and a recycling process for recovering the crushed sealing portions 3.

[0036] The cooling process of the cooling disassembly step cools the battery module 1 by causing the resin of the sealing part 3 to become brittle at low temperatures. In this cooling process, the battery module 1 is cooled to below -60°C. The pressing process of the cooling disassembly step presses the cooled battery module 1 in the stacking direction to freeze and crush the sealing part 3. In the pressing process, stress is intentionally applied to the sealing part 3, which has become brittle at low temperatures due to cooling, causing the sealing part 3 to freeze and crush. Figure 6 As shown, during cooling and pressing, stress concentrates in the thin portion of the resin in the sealing part 3, and cracks originate from this point. With the sealing part 3 cracked starting from the gap caused by the recess 4, the sealing part 3 is pressed in the lamination direction, thereby... Figure 7 As shown, the resin in the sealing part 3 cracked, and the cracked resin 30 fell out. Furthermore, in Figure 7 The image shows arrows indicating the cooling environment and the direction of the pressing load during the pressing process.

[0037] The recycling process is a process of recovering the electrolyte that fills the space between the bipolar electrodes through heating, depressurization, and drying (step S4). The recycling process recovers the electrolyte contained in the laminate, bipolar electrodes, and diaphragm, which are the constituent components remaining after the cooling and disassembly process, by depressurization and drying.

[0038] Figure 8 This diagram illustrates an example of the cooling and disassembly process. In the cooling and disassembly process, the energy storage module 1 obtained from the package disassembly process is conveyed by the pinch roller 41 while the cooling process, pressing process, and recycling process are performed.

[0039] The cooling process cools the entire battery module 1 using methods such as forced cooling and contact cooling. In this cooling process, the battery module 1 is cooled to below -60°C. For example, the cooling process may include blowing cryogenic solvents such as liquid nitrogen (-196°C) or dry ice (-79°C) onto the battery module 1, and bringing the cooled components into contact with the battery module 1. In the cooling process, cryogenic solvent 43 is blown onto the entire battery module 1 by the cooling device 42. In this cooling process, it is not necessary to cool uniformly to the interior of the battery module 1; as long as the sealing portion 3 is cooled from the outer periphery to a predetermined range inward, the resin constituting the sealing portion 3 can be made to become brittle at low temperatures.

[0040] The pressing process presses the cooled energy storage module 1 in the stacking direction. In the pressing process, the entire energy storage module 1 is pressed by the pressing device 44, causing the sealing part 3 to freeze and pulverize. In the pressing process, the pressing device 44 is used, which is capable of pressing the contact part while cooling it using a pressing mold that can simultaneously press a part or all four sides of the sealing part 3.

[0041] exist Figure 8 In the example shown, the pressing device 44 has a pair of pressure rollers. These pressure rollers are fully cooled rollers used to press the battery storage module 1 in a manner that clamps it in the stacking direction. For example, the pressure rollers are cooled through a cooling process. In the pressing device 44, the battery storage module 1 is conveyed using a pinch roller 41. The pressing device 44 presses the battery storage module 1 using the pressure rollers while conveying it. For example, the surface of the pressure rollers is formed into an uneven shape to transfer stress to the interior of the sealing portion 3. The unevenness of the pressure roller surface can break the sealing portion 3.

[0042] The recycling process recovers resin 30 by causing the seal 3, which has become brittle due to cooling and stress, to crack and slip off. In the recycling process, the crushed resin 30 is recovered by applying external force to the energy storage module 1 after the pressing process, through methods such as blowing air with a blower 45 and applying vibration. Figure 8 In the example shown, a blower 45 and a tray 46 are provided downstream of the pressure roller in the pressing device 44. The resin 30 separates from the bipolar electrode and falls due to the air blown by the blower 45. In the recycling process, the fallen resin 30 is recovered via the tray 46. If liquid nitrogen is used in the cooling process, the liquid nitrogen evaporates during the falling of the resin 30. The broken sealing section 3 is brought back to room temperature via the tray 46 and then washed with water (acid washing), thereby removing electrolyte components and recovering only the carbon component. At this time, the sealing section 3 can be submerged in water using a wire mesh or similar device to remove salt and recover the resin 30. Alternatively, if electrolyte adheres to the fallen resin 30, pre-adding excess water to the tray 46 allows for safer recycling. In this case, if a weak acid aqueous solution is used instead of water, lithium carbonate and other substances produced after deterioration can also be dissolved, allowing for solid-liquid separation of only the resin 30.

[0043] The resin 30 obtained through the recycling process can be used as a raw material to re-form the resin sheet into a molding material, and can be recycled as a raw material. Aluminum and copper will not break due to the toughness of the metal, and the adhesive layer 13 of the current collector foil 10 is epoxy resin, which has a very low heat resistance temperature of -268°C, so only the electrodes can be effectively recycled.

[0044] During the cooling disassembly process, the sealing part 3, which becomes brittle due to cooling, is crushed. However, even if not all the resin constituting the sealing part 3 can be recovered, it will not be a problem. Through the cooling disassembly process, not only can the electrodes be separated for each current collector foil 10, but an opening for electrolyte recovery can also be ensured. By forming the opening using the cooling disassembly process, depressurized drying can be performed in the next process to recover the electrolyte.

[0045] Furthermore, the battery module 1 can be disassembled without baking through a cooling disassembly process. By performing the cooling disassembly process, the resin constituting the sealing part 3 can be recovered in a pulverized state and can be used as a recycling material. The recovered resin 30 may also contain electrolyte, so it is washed with weakly acidic water and dissolved solid salts such as lithium carbonate, making it easy to use as a raw material.

[0046] As explained above, according to the embodiment, the resin forming the outer frame of the energy storage module 1 can be easily separated from the current collector foil 10 by means of the recess 4 provided in the sealing portion 3. Therefore, the energy storage module 1 can be easily disassembled. Furthermore, the energy storage module 1 can be disassembled without affecting the current collector foil 10, the positive electrode, and the negative electrode, and the resin that can be recycled can be recovered.

[0047] Furthermore, in the current collector foil 10, the combination of metal foils constituting the positive and negative electrode foils is not limited to the combination of aluminum foil 11 and copper foil 12. The metal foil included in the current collector foil 10 can also be lead foil. The bipolar battery containing the current collector foil 10 is not limited to a bipolar lithium-ion battery, but can also be a bipolar lead-acid battery or a bipolar nickel-metal hydride battery.

[0048] Furthermore, there is no particular limitation on the surface on which the recess 4 is provided in the sealing member. The recess 4 can be provided on any one surface of the sealing member, or it can be provided on both surfaces of the sealing member. For example, when the recess 4 is provided in the first sealing member, it is not limited to the surface that contacts the current collector foil 10, and the recess 4 can also be provided on the surface that does not contact the current collector foil 10.

[0049] Furthermore, the recess 4 is not limited to the sealing portion 3 disposed between adjacent current collector foils 10 in the stacking direction, but may also be provided in a sealing portion 3 disposed on the outer side of the positive terminal electrode in the stacking direction, or a sealing portion 3 disposed on the outer side of the negative terminal electrode in the stacking direction. For example, the energy storage module 1 may also be an energy storage module in which the sealant film 21 is formed in a concave-convex shape. In short, when viewing the energy storage module 1 from the stacking direction, in the energy storage module 1, it is sufficient that the recess 4 is provided in the resin of the sealing portion 3 at the position overlapping the periphery of the current collector foil 10.

Claims

1. A power storage module, characterized in that, It features bipolar electrodes, an electrode stack, and a resin-sealed part. The bipolar electrode has a positive active material on one side of the current collecting foil and a negative active material on the other side of the current collecting foil. The electrode stack is composed of multiple bipolar electrodes stacked together. The resin sealing portion is disposed at the periphery of the current collector foil, sealing adjacent bipolar electrodes in the stacking direction of the electrode laminate with each other. The sealing portion has a recess in which the peripheral portions of adjacent current collector foils in the stacking direction form a gap with each other.

2. The energy storage module according to claim 1, characterized in that, The sealing part is composed of multiple sealing components. The recess is provided in at least one of the plurality of sealing members.

3. The energy storage module according to claim 2, characterized in that, The current collector foil is a current collector formed by bonding a positive electrode foil and a negative electrode foil together with an adhesive layer. The recess is provided in the first sealing member, which is at least in contact with the periphery of the current collector foil.

4. The energy storage module according to claim 3, characterized in that, The recess is formed in a concave shape in the stacking direction and is provided on the surface of the first sealing member that contacts the periphery of the current collector foil.

5. A method for disassembling a battery storage module, comprising the method for disassembling the battery storage module as described in any one of claims 1 to 4. The process includes a cooling and disassembly step, in which the sealing part is cooled to below -60°C and pressed in the stacking direction to freeze and pulverize it.

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