Battery processing method and battery

Abstract

To provide a battery processing method that can satisfactorily deactivate a battery.SOLUTION: A battery processing method has an immersion step of immersing a battery including an Al terminal in a processing liquid and reducing the voltage of the battery through external short circuit via the processing liquid. The processing liquid contains water and a supporting electrolyte, and the Al terminal has, on at least part of its surface, a protective layer that prevents elution of the Al terminal into the processing liquid.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a method for treating a battery and a battery.

Background Art

[0002] A battery usually has terminals for taking out electricity from an electrode body which is a power generation element. For example, Patent Document 1 discloses a battery module having a laminated exterior flat battery having a positive electrode terminal lead and a negative electrode terminal lead, and it is disclosed that the positive electrode terminal lead is made of aluminum. Further, Patent Document 2 discloses that the resistance to an electrolytic solution is improved by treating the surface of an exterior body made of aluminum.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recycling a battery, it is desired to reduce the residual voltage of the battery and deactivate the battery. As a method for deactivating a battery, for example, a method of externally short-circuiting by immersing the battery in a treatment liquid (for example, salt water) can be mentioned. In a battery including an aluminum terminal (Al terminal), the Al terminal may be deteriorated by the treatment liquid, and it may be difficult to deactivate the battery satisfactorily.

[0005] The present disclosure has been made in view of the above circumstances, and a main object thereof is to provide a method for treating a battery capable of deactivating the battery satisfactorily.

Means for Solving the Problems

[0006] [1] A battery containing an Al terminal is immersed in a treatment liquid, and has an immersion step of reducing the voltage of the battery by an external short circuit through the treatment liquid. The treatment liquid contains water and a supporting salt. The Al terminal has a protective layer on at least a part of its surface to suppress elution of the Al terminal into the treatment liquid, which is a method for treating a battery.

[0007] [2] The method for treating a battery has a protective layer forming step of forming the protective layer on the surface of the Al terminal before the immersion step, which is the method for treating a battery according to [1].

[0008] [3] The battery has an electrode body, an exterior body covering the electrode body, and the Al terminal electrically connected to the electrode body and partially exposed from the exterior body. The protective layer is formed on the surface of the Al terminal located inside the exterior body, which is the method for treating a battery according to [1].

[0009] [4] The protective layer is an aluminum oxide layer, which is the method for treating a battery according to any one of [1] to [3].

[0010] [5] The aluminum oxide layer is a boehmite layer, which is the method for treating a battery according to [4].

[0011] [6] The protective layer is a conductive resin layer, which is the method for treating a battery according to any one of [1] to [3].

[0012] [7] The protective layer is a plating layer, which is the method for treating a battery according to any one of [1] to [3].

[0013] [8] A battery containing an Al terminal is immersed in a treatment liquid, and has an immersion step of reducing the voltage of the battery by an external short circuit through the treatment liquid. The treatment liquid contains water and a supporting salt, A method for treating a battery, wherein the material of the Al terminal is an Al-Mg-Si based alloy or an Al-Ni clad material.

[0014] [9] A battery including an Al terminal, The battery, wherein the Al terminal has a protective layer on at least a part of its surface to suppress elution of the Al terminal into the treatment liquid.

[0015]

[10] The battery includes an electrode body, an exterior body covering the electrode body, and the Al terminal electrically connected to the electrode body and partially exposed from the exterior body. The battery according to [9], wherein, when viewed in the thickness direction, the protective layer is selectively formed in a region including the end portion of the Al terminal on the exterior body side.

[0016]

[11] A battery including an Al terminal, The battery, wherein the material of the Al terminal is an Al-Mg-Si based alloy or an Al-Ni clad material.

[0017]

[12] The battery according to any one of [9] to

[11] , having a laminated exterior body.

[0018]

[13] The battery according to any one of [9] to

[12] , which is a solid-state battery. [Advantages of the Invention]

[0019] In the present disclosure, there is an effect that the battery can be deactivated well. [Brief Description of the Drawings]

[0020]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0021] Hereinafter, a method for treating a battery and a battery in the present disclosure will be described in detail with reference to the drawings. Each of the drawings shown below is schematically illustrated, and the size and shape of each part are exaggerated as appropriate for easy understanding. Also, in this specification, when expressing the manner of arranging one member with respect to another member, when simply described as "above" or "below", unless otherwise specified, it includes both the case where another member is arranged directly above or directly below so as to be in contact with a certain member, and the case where another member is arranged above or below a certain member via another member.

[0022] A. Method for Treating a Battery The method for treating a battery in the present disclosure can be roughly classified into two embodiments. The method for treating a battery in the present disclosure will be described separately for the first embodiment and the second embodiment.

[0023] A-1. First Embodiment The method for treating a battery in the first embodiment has an immersion step of immersing a battery including an Al terminal in a treatment liquid and reducing the voltage of the battery by an external short circuit through the treatment liquid. The treatment liquid contains water and a supporting salt, and the Al terminal has a protective layer on at least a part of its surface to suppress the elution of the Al terminal into the treatment liquid.

[0024] Figs. 1(a) and 1(b) are a schematic plan view and a schematic side view illustrating a battery according to the first embodiment. As shown in Figs. 1(a) and 1(b), the battery 100 includes an electrode body 10, an exterior body 20 covering the electrode body 10, and terminals 30 (30A, 30B) electrically connected to the electrode body 10 and partially exposed from the exterior body 20. At least one of the terminal 30A and the terminal 30B is an Al terminal. In Figs. 1(a) and 1(b), the terminal 30A corresponds to the Al terminal 30X.

[0025] Fig. 2 is a schematic side view illustrating a method of treating the battery according to the first embodiment. As shown in Fig. 2, a treatment liquid 50 is introduced into a treatment bath 40, and the battery 100 is immersed in the treatment liquid 50. When the terminals 30A and 30B are electrically connected through the treatment liquid 50, an external short circuit occurs and the voltage of the battery 100 decreases. In the first embodiment, the Al terminal 30X has a protective layer 60 on at least a part of its surface to suppress the elution of the Al terminal 30X into the treatment liquid 50.

[0026] According to the first embodiment, since the Al terminal has a protective layer on its surface, the battery can be deactivated well. As described above, when recycling a battery, it is desirable to reduce the residual voltage of the battery and deactivate the battery. By deactivating the battery, subsequent processes such as a battery disassembly process can be performed safely. As a method of deactivating a battery, a method of causing an external short circuit by immersing the battery in a treatment liquid (for example, salt water) can be mentioned. In a battery including an Al terminal, it may be difficult to deactivate the battery well because the Al terminal deteriorates due to the treatment liquid. For example, when corrosion (elution) of the Al terminal occurs due to the treatment liquid and the Al terminal exposed from the exterior body slides off, the decrease in the residual voltage due to the external short circuit may not occur or the rate of decrease may be significantly reduced.

[0027] On the other hand, in the first embodiment, a protective layer for suppressing the elution of the Al terminal into the treatment liquid is formed on the surface of the Al terminal. Thereby, it is possible to suppress the deterioration of the Al terminal due to the treatment liquid. Therefore, when the battery is immersed in the treatment liquid, an external short circuit can be maintained and the battery can be deactivated well.

[0028] 1. Immersion process In the first embodiment, the immersion process is a process of immersing a battery including an Al terminal in a treatment liquid and reducing the voltage of the battery by an external short circuit through the treatment liquid. In the first embodiment, the Al terminal has a protective layer on at least a part of its surface to suppress the elution of the Al terminal into the treatment liquid. The protective layer may be formed by performing a protective layer forming process before the immersion process. Details of the protective layer forming process will be described later. Note that in the battery treatment method according to the first embodiment, it is not necessary to completely prevent the deterioration of the Al terminal, and it is sufficient that the deterioration of the Al terminal can be suppressed by the protective layer to the extent that the battery can be deactivated well.

[0029] (1) Battery As shown in FIGS. 1(a) and 1(b), the battery 100 generally includes an electrode body 10, an exterior body 20 covering the electrode body 10, and terminals 30 (30A, 30B) electrically connected to the electrode body 10 and partially exposed from the exterior body 20. At least one of the terminals 30A and 30B is an Al terminal. In FIGS. 1(a) and 1(b), the terminal 30A corresponds to the Al terminal 30X.

[0030] In the first embodiment, a unit composed of an electrode body, an exterior body, and a pair of terminals may be referred to as a "cell". The battery to be processed by the processing method according to the first embodiment may have one cell or a plurality of cells. The plurality of cells are generally stacked in the thickness direction.

[0031] (i) Terminal The battery in the first embodiment usually has a positive electrode terminal and a negative electrode terminal. At least one of the positive electrode terminal and the negative electrode terminal is an Al terminal. Among them, it is preferable that at least the positive electrode terminal is an Al terminal. The Al terminal is a terminal containing at least aluminum. The Al terminal preferably contains aluminum as the main component of the metal component. In the Al terminal, the ratio of aluminum to all metal components is, for example, 50% by weight or more, and may be 70% by weight or more, or may be 90% by weight or more. Examples of the material of the Al terminal include aluminum and aluminum alloy.

[0032] The shape of the Al terminal is not particularly limited. Also, the thickness of the Al terminal is not particularly limited, but the thinner the Al terminal, the greater the influence of the deterioration of the Al terminal by the treatment liquid. The thickness of the Al terminal refers to the length of the Al terminal in the normal direction of the main surface (the surface with the largest area) of the Al terminal. The thickness of the Al terminal is, for example, 5 mm or less, and may be 3 mm or less, 1 mm or less, 0.8 mm or less, or 0.6 mm or less. On the other hand, the thickness of the Al terminal is, for example, 0.1 mm or more.

[0033] The Al terminal has a protective layer on at least a part of its surface to suppress the elution of the Al terminal into the treatment liquid. The Al terminal and the protective layer may be arranged to be in contact with each other, or may be arranged via another layer.

[0034] An example of the protective layer is an aluminum oxide layer. The aluminum oxide layer is formed, for example, by oxidizing the surface of the Al terminal. Note that the "aluminum oxide layer" in the first embodiment does not include the natural oxide film of the Al terminal. The natural oxide film is usually 5 nm or less. In contrast, the thickness of the aluminum oxide layer in the first embodiment is usually greater than 5 nm.

[0035] Examples of the aluminum oxide layer include a boehmite layer and an anodized layer. The boehmite layer is formed, for example, by performing a boehmite treatment on an Al terminal. The boehmite treatment is a type of chemical conversion treatment. For example, by bringing the Al terminal into contact with water or steam at a high temperature (e.g., 70 °C or higher), a chemical treatment is performed to form an aluminum oxide layer on the surface of the Al terminal. The thickness of the boehmite layer is, for example, 100 nm or more and 2 μm or less.

[0036] The anodized layer is formed, for example, by performing an anodizing treatment on an Al terminal. The anodizing treatment corresponds to an anodic oxidation treatment. For example, by using the Al terminal as an anode and performing an electrolytic treatment, an electrical treatment is performed to form an aluminum oxide layer on the surface of the Al terminal. The thickness of the anodized layer is, for example, 0.5 μm or more and 50 μm or less, and may be 1 μm or more and 20 μm or less. Also, in the first embodiment, an aluminum oxide layer may be formed by heating the surface of the Al terminal.

[0037] As another example of the protective layer, a conductive resin layer can be mentioned. The conductive resin layer has, for example, a resin (including rubber) and a conductor. Examples of the above resin include polyolefin resins such as polyethylene, polypropylene, and polystyrene; imide resins such as polyimide and polyamideimide; amide resins such as polyamide; acrylic resins such as polymethyl acrylate, polyethyl acrylate, polypropyl acrylate, polybutyl acrylate, polyhexyl acrylate, poly(2-ethylhexyl) acrylate, polydecyl acrylate, and polyacrylic acid; methacrylic acid resins such as polymethyl methacrylate, polyethyl methacrylate, polybutyl methacrylate, poly(2-ethylhexyl) methacrylate, and polymethacrylic acid; carboxylic acid resins such as polyitaconic acid, polycrotonic acid, polyfumaric acid, polyangelic acid, and carboxymethyl cellulose; fluorine-based resins such as polyvinylidene fluoride (PVDF), polyvinylidene fluoride - hexafluoropropylene copolymer (PVDF-HFP), and polytetrafluoroethylene; and rubbers such as butadiene rubber, hydrogenated butadiene rubber, styrene-butadiene rubber (SBR), hydrogenated styrene-butadiene rubber, nitrile-butadiene rubber, hydrogenated nitrile-butadiene rubber, ethylene-propylene rubber, and fluororubber. On the other hand, examples of the above conductor include carbon materials, metal particles, and conductive polymers. Examples of the carbon material include particulate carbon materials such as acetylene black (AB) and ketjen black (KB), and fibrous carbon materials such as carbon fibers, carbon nanotubes (CNT), and carbon nanofibers (CNF). As a method for forming the conductive resin layer, for example, a method of coating a slurry containing a resin, a conductor, and a solvent on an Al terminal and drying it can be mentioned.

[0038] As yet another example of the protective layer, a plating layer can be mentioned. The metal contained in the plating layer may be a metal having a lower ionization tendency than the Al terminal (a metal with a noble natural potential). A metal having a lower ionization tendency than the Al terminal has high resistance to the treatment liquid. Examples of such metals include iron, iron alloys, titanium, titanium alloys, copper, copper alloys, lead, lead alloys, gold, gold alloys, silver, silver alloys, palladium, and palladium alloys. Note that since the treatment liquid usually does not penetrate between the plating layer and the Al terminal, corrosion (galvanic corrosion) of the Al terminal does not occur. On the other hand, the metal may be a metal having an ionization tendency comparable to that of the Al terminal or a metal having a greater ionization tendency than the Al terminal (a metal with a base natural potential). Examples of such metals include magnesium, magnesium alloys, zinc, and zinc alloys. When such a metal is used, corrosion of the Al terminal does not occur, while corrosion of the plating layer progresses. Therefore, for example, it is preferable to set the thickness of the plating layer to be sufficiently large. Examples of the method for forming the plating layer include an electrolytic plating method and an electroless plating method.

[0039] The thickness of the protective layer is not particularly limited, but for example, it may be 10 nm or more, may be 50 nm or more, may be 100 nm or more, or may be 500 μm or more. On the other hand, the thickness of the protective layer is, for example, 50 μm or less.

[0040] FIG. 3(a) is a schematic plan view illustrating a part of the battery (before the formation of the protective layer) in the present disclosure, and FIG. 3(b) is a cross-sectional view taken along the line A-A of FIG. 3(a). FIG. 3(c) is a schematic plan view illustrating a part of the battery (after the formation of the protective layer) in the present disclosure, and FIG. 3(d) is a cross-sectional view taken along the line A-A of FIG. 3(c). As shown in FIGS. 3(a) and 3(b), the Al terminal 30X is electrically connected to the electrode body 10 and a part thereof is exposed from the exterior body 20. In the first embodiment, before the immersion step, as shown in FIGS. 3(c) and 3(d), a protective layer 60 covering at least a part of the Al terminal 30X may be formed (protective layer formation step). On the other hand, in the first embodiment, the protective layer formation step may not be performed before the immersion step. That is, the battery before performing the battery processing method in the first embodiment may have a protective layer in advance. In this case, as shown in FIG. 4, the protective layer 60 may be formed on the surface of the Al terminal 30X located inside the exterior body 20. Conversely, as shown in FIG. 3(d), the protective layer 60 may not be formed on the surface of the Al terminal 30X located inside the exterior body 20.

[0041] As shown in FIGS. 3(c), 3(d) and FIG. 4, the protective layer 60 may be formed on the entire Al terminal 30X exposed from the exterior body 20. On the other hand, although not particularly shown, the protective layer may be formed on a part of the Al terminal exposed from the exterior body. Also, as shown in FIGS. 3(c), 3(d) and FIG. 4, the protective layer 60 may be formed on both main surfaces of the Al terminal 30X exposed from the exterior body 20. On the other hand, although not particularly shown, the protective layer may be formed on only one of the main surfaces of the Al terminal exposed from the exterior body.

[0042] As shown in Fig. 5(a), when viewed from the thickness direction (z direction), the protective layer 60 may be formed so as to cover the entire Al terminal 30X. On the other hand, as shown in Fig. 5(b), when viewed from the thickness direction (z direction), the protective layer 60 may be formed so as to cover a part of the Al terminal 30X. In Fig. 5(b), the protective layer 60 is formed so as to selectively cover the region including the end portion of the Al terminal 30X on the exterior body 20 side. By protecting the region (root region) including the end portion of the Al terminal 30X on the exterior body 20 side, when the battery is immersed in the treatment liquid, an external short circuit can be further maintained, and the battery can be deactivated better. Further, when the battery before performing the battery treatment method in the first embodiment has a protective layer that selectively covers the region including the end portion of the Al terminal on the exterior body side in advance, the protective layer formation step described later can be omitted while suppressing an increase in resistance due to the protective layer. Further, "the protective layer is formed so as to selectively cover the region including the end portion of the Al terminal on the exterior body side" means that, as shown in Fig. 5(b), there is a region where the protective layer 60 is not formed on the side opposite to the exterior body 20 side of the root region. Also, when viewed from the thickness direction, the area of the Al terminal is S a is defined, and the area of the region where the Al terminal and the protective layer overlap is S b In the case of, the area S a with respect to the area S b The ratio of (S b / S a ) is not particularly limited, but may be, for example, 10% or more, 30% or more, 50% or more, or 70% or more.

[0043] (ii) Electrode body The electrode body in the first embodiment functions as a power generation element of the battery. The electrode body usually has a positive electrode current collector, a positive electrode active material layer, an electrolyte layer, a negative electrode active material layer, and a negative electrode current collector in this order in the thickness direction.

[0044] Figs. 6(a) and 6(b) are schematic cross-sectional views illustrating the electrode body in the first embodiment. The electrode body 10 shown in Fig. 6(a) has a negative electrode current collector 1, a negative electrode active material layer 2, an electrolyte layer 3, a positive electrode active material layer 4, and a positive electrode current collector 5 in this order in the thickness direction (z direction). Further, the negative electrode current collector 1 has a negative electrode tab 1t for connecting to a negative electrode terminal (not shown), and the positive electrode current collector 5 has a positive electrode tab 5t for connecting to a positive electrode terminal (not shown).

[0045] The electrode body 10 shown in Fig. 6(b) has a negative electrode current collector 1, a negative electrode active material layer 2x, an electrolyte layer 3x, a positive electrode active material layer 4x, and a positive electrode current collector 5x which are arranged in order from one surface of the negative electrode current collector 1 in the thickness direction (z direction), and a negative electrode active material layer 2y, an electrolyte layer 3y, a positive electrode active material layer 4y, and a positive electrode current collector 5y which are arranged in order from the other surface of the negative electrode current collector 1 in the thickness direction (z direction).

[0046] In Figs. 6(a) and 6(b), the positive electrode tab 5t and the negative electrode tab 1t are arranged to face each other on the side surface of the electrode body 10, forming a so-called double-tab structure. On the other hand, although not particularly shown, the positive electrode tab and the negative electrode tab may be arranged on the same side surface of the electrode body, forming a so-called single-tab structure. Also, as shown in Figs. 6(a) and 6(b), the electrode body 10 may be of the single-sheet type. Further, although not particularly shown, the electrode body may be of the wound type. Also, a unit composed of a positive electrode active material layer, an electrolyte layer, and a negative electrode active material layer may be referred to as a "power generation unit". The electrode body in the first embodiment may have one power generation unit or a plurality of power generation units. The plurality of power generation units are usually laminated in the thickness direction.

[0047] The positive electrode active material layer contains at least a positive electrode active material. The positive electrode active material layer may further contain at least one of an electrolyte, a conductive material, and a binder. Examples of the positive electrode active material include oxide active materials. Examples of the oxide active material include, for example, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, LiNi 0.8 Co 0.15 Al0.05 Examples include rock salt layer-type active materials such as O2, spinel-type active materials such as LiMn2O4, and olivine-type active materials such as LiFePO4. The shape of the positive electrode active material is, for example, particulate.

[0048] The electrolyte may be a solid electrolyte or a liquid electrolyte (electrolyte solution). The solid electrolyte may be an organic solid electrolyte such as a gel electrolyte, or an inorganic solid electrolyte such as a sulfide solid electrolyte or an oxide solid electrolyte. Among these, the solid electrolyte is preferably a sulfide solid electrolyte because of its high ionic conductivity. On the other hand, the liquid electrolyte is not particularly limited, and known electrolytes can be employed. Examples of the conductive material include carbon materials. Examples of the binder include rubber-based binders and fluoride-based binders.

[0049] The negative electrode active material layer contains at least a negative electrode active material. The negative electrode active material layer may further contain at least one of an electrolyte, a conductive material, and a binder. Examples of the negative electrode active material include metal active materials such as Li, Si, and Sn, carbon active materials such as graphite, and oxide active materials such as Li4Ti5O 12 and the like.

[0050] The electrolyte layer is disposed between the positive electrode active material layer and the negative electrode active material layer and contains at least an electrolyte. The electrolyte may be a solid electrolyte or a liquid electrolyte. The electrolyte is the same as described above. The electrolyte layer may be a solid electrolyte layer containing a solid electrolyte. Furthermore, the solid electrolyte is preferably a sulfide solid electrolyte. Generally, a battery having a solid electrolyte layer containing an inorganic solid electrolyte is called a solid battery. The solid battery may be a semi-solid battery or an all-solid battery. In the present disclosure, a semi-solid battery is a battery in which the electrolyte layer has an inorganic solid electrolyte and a liquid component (for example, an ionic liquid). In the present disclosure, an all-solid battery is a battery in which the electrolyte layer has only an inorganic solid electrolyte as an electrolyte.

[0051] The positive current collector conducts the current collection of the positive electrode active material layer. Examples of the material of the positive current collector include metals such as aluminum, SUS, and nickel. Examples of the shape of the positive current collector include a foil shape. The positive current collector usually has a positive tab for connecting to the positive terminal. Also, the negative current collector conducts the current collection of the negative electrode active material layer. Examples of the material of the negative current collector include metals such as copper, SUS, and nickel. Examples of the shape of the negative current collector include a foil shape. The negative current collector usually has a negative tab for connecting to the negative terminal.

[0052] (iii) Outer package The outer package in the first embodiment may be a laminate type outer package or a case type outer package. The laminate type outer package is also referred to as a pouch type outer package and is an outer package using a laminate film. The laminate type outer package has at least an inner resin layer and a metal layer. The inner resin layer functions as a sealant layer. The inner resin layer preferably contains a thermoplastic resin. Examples of the thermoplastic resin include polyolefins such as polyethylene and polypropylene, polystyrene, and polyvinyl chloride. The thickness of the inner resin layer is not particularly limited, but for example, it is 30 μm or more and 150 μm or less.

[0053] The metal layer functions as a barrier layer. Examples of the metal used for the metal layer include aluminum, aluminum alloy, and stainless steel. The thickness of the metal layer is not particularly limited, but for example, it is 20 μm or more and 100 μm or less. Also, the laminate type outer package may have an outer resin layer on the side opposite to the inner resin layer with respect to the metal layer. The outer resin layer functions as an insulating layer or a protective layer. The outer resin layer preferably contains a thermoplastic resin. Examples of the thermoplastic resin include polyesters such as polyethylene terephthalate (PET) and nylon. The thickness of the outer resin layer is not particularly limited, but for example, it is 20 μm or more and 100 μm or less.

[0054] The case-type exterior body is, for example, an exterior body made of metal. Examples of the material constituting the case-type exterior body include aluminum and aluminum alloys. Further, a material obtained by performing plastic working on aluminum or an aluminum alloy and work-hardening it may be used. Further, the thickness of the case-type exterior body is not particularly limited and is selected to such an extent that a desired rigidity is obtained.

[0055] (iv) Battery Examples of the battery in the first embodiment include secondary batteries such as lithium ion secondary batteries. Further, examples of the use of the battery before being processed by the processing method in the first embodiment include power sources for vehicles such as hybrid vehicles (HEVs), plug-in hybrid vehicles (PHEVs), battery electric vehicles (BEVs), gasoline vehicles, and diesel vehicles. In particular, it is preferably a battery that has been used as a drive power source for a hybrid vehicle (HEV), a plug-in hybrid vehicle (PHEV), or a battery electric vehicle (BEV). It may also be a battery that has been used as a power source for a moving body other than a vehicle (for example, a railway, a ship, an aircraft), or a battery that has been used as a power source for an electrical product such as an information processing device.

[0056] (2) Processing liquid The processing liquid in the first embodiment contains water and a supporting salt.

[0057] The supporting salt is used to improve the conductivity of the processing liquid. Further, the supporting salt usually does not have a function of suppressing the elution of the Al terminal. The supporting salt has a cation component and an anion component. Examples of the cation component of the supporting salt include alkali metal ions such as Na and K; alkaline earth metal ions such as Mg and Ca. On the other hand, examples of the anion component of the supporting salt include chloride ions. Specific examples of the processing liquid include NaCl, KCl, MgCl2, and CaCl2. Further, the processing liquid may contain only one kind of supporting salt or may contain two or more kinds of supporting salts.

[0058] At least a part of the supporting salt is dissolved in water. The concentration of the supporting salt in the treatment liquid is not particularly limited, but for example, it may be 0.01 mol / kg or more and 5.0 mol / kg or less, and may be 0.1 mol / kg or more and 3.0 mol / kg or less. In the first embodiment, the above concentration of the supporting salt is defined as the ratio of the number of moles of the supporting salt to the weight of water contained in the treatment liquid. Further, as a method for preparing the treatment liquid, for example, a method of dissolving the supporting salt in water can be mentioned.

[0059] (3) Immersion method In the immersion step in the first embodiment, a battery including an Al terminal is immersed in the treatment liquid, and the voltage of the battery is reduced by an external short circuit through the treatment liquid. Specifically, as shown in FIG. 2, the treatment liquid 50 is put into the treatment bath 40, and the battery 100 is immersed in the treatment liquid 50.

[0060] The temperature of the treatment liquid in the immersion step is not particularly limited. For example, since the freezing point of brine is about -20°C, the temperature of the treatment liquid is preferably -20°C or higher, more preferably 0°C or higher. On the other hand, the temperature of the treatment liquid is, for example, 60°C or lower, and may be 40°C or lower. Also, the temperature of the treatment liquid in the immersion step may be the same as room temperature.

[0061] The treatment time in the immersion step is not particularly limited, but from the viewpoint of workability, for example, it is preferably 1 hour or more and 50 hours or less, and more preferably 2 hours or more and 25 hours or less.

[0062] 2. Protective layer formation step The method for treating the battery in the first embodiment may have a protective layer formation step of forming the protective layer on the surface of the Al terminal before the immersion step.

[0063] The method for forming the protective layer is not particularly limited and is appropriately selected according to the type of the protective layer. Specific examples of the method for forming the protective layer are as described above.

[0064] A-2. Second embodiment The battery processing method in the second embodiment has an immersion step of immersing a battery including an Al terminal in a processing liquid and reducing the voltage of the battery by an external short circuit through the processing liquid. The processing liquid contains water and a supporting salt, and the material of the Al terminal is an Al-Mg-Si based alloy or an Al-Ni clad material.

[0065] Figs. 1(a) and (b) are a schematic plan view and a schematic side view illustrating the battery in the second embodiment. As shown in Figs. 1(a) and (b), the battery 100 has an electrode body 10, an exterior body 20 covering the electrode body 10, and terminals 30 (30A, 30B) electrically connected to the electrode body 10 and partially exposed from the exterior body 20. At least one of the terminals 30A and 30B is an Al terminal. In Figs. 1(a) and (b), the terminal 30A corresponds to the Al terminal 30X.

[0066] Fig. 7 is a schematic side view illustrating the battery processing method in the second embodiment. As shown second, a processing liquid 50 is poured into a processing bath 40, and the battery 100 is immersed in the processing liquid 50. An external short circuit occurs when the terminals 30A and 30B are electrically connected through the processing liquid 50, and the voltage of the battery 100 decreases. In the second embodiment, the material of the Al terminal 30X is an Al-Mg-Si based alloy or an Al-Ni clad material.

[0067] According to the second embodiment, since the material of the Al terminal is a specific material, the battery can be deactivated well. Specifically, since the material of the Al terminal is a specific material, deterioration of the Al terminal by the processing liquid can be suppressed. Therefore, when the battery is immersed in the processing liquid, an external short circuit can be maintained, and the battery can be deactivated well.

[0068] The immersion step in the second embodiment is a step of immersing a battery including an Al terminal in a processing liquid and reducing the voltage of the battery by an external short circuit through the processing liquid. In the second embodiment, the material of the Al terminal is an Al-Mg-Si based alloy or an Al-Ni clad material.

[0069] The Al-Mg-Si alloy is a so-called 6000 series aluminum alloy, which is an aluminum alloy obtained by adding Mg (magnesium) and Si (silicon) to Al (aluminum) to increase corrosion resistance. The Al-Mg-Si alloy contains at least Al, Mg, and Si, and may further contain one or more trace metal elements (including semi-metal elements). Examples of the trace metal elements include Cu, Mn, Fe, Cr, Ti, B, Zn, and Zr. Also, the content of Al in the Al-Mg-Si alloy is, for example, 50% by weight or more, may be 70% by weight or more, or may be 90% by weight or more.

[0070] The Al-Ni clad material is a clad material having a Ni (nickel) layer on the surface of an Al (aluminum) layer. The Al-Ni clad material may have a Ni layer on one side of the Al layer or may have Ni layers on both sides of the Al layer. Also, the Al-Ni clad material may be an overlay clad material, an inlay clad material, or an edge lay clad material.

[0071] Regarding the immersion process and the details of the battery in the second embodiment, since they are the same as the content described in the first embodiment above, the description here is omitted.

[0072] B. Battery The battery in the present disclosure is a battery including an Al terminal, and the Al terminal may have a protective layer on at least a part of its surface to suppress the elution of the Al terminal into the treatment liquid. Also, the battery in the present disclosure is a battery including an Al terminal, and the material of the Al terminal may be an Al-Mg-Si alloy or an Al-Ni clad material.

[0073] According to the present disclosure, by having a protective layer on the surface of the Al terminal or by using a specific material as the material of the Al terminal, the battery can be deactivated well when the battery is recycled. Regarding the battery in the present disclosure, since it is the same as the content described in the above "A. Battery treatment method", the description here is omitted.

[0074] The present disclosure is not limited to the above embodiments. The above embodiments are examples, and any configuration that has substantially the same configuration as the technical idea described in the claims of the present disclosure and exhibits the same operational effects is included in the technical scope of the present disclosure.

Description of Reference Numerals

[0075] 1... Negative electrode current collector 2... Negative electrode active material layer 3... Electrolyte layer 4... Positive electrode active material layer 5... Positive electrode current collector 10... Electrode body 20... Outer package 30... Terminal 40... Treatment bath 50... Treatment liquid 60... Protective layer 100... Battery

Claims

1. A battery containing an Al terminal is immersed in a treatment liquid, and has an immersion step of reducing the voltage of the battery by an external short circuit through the treatment liquid. The treatment liquid contains water and a supporting salt. The Al terminal has a protective layer on at least a part of its surface for suppressing elution of the Al terminal into the treatment liquid, and a method for treating a battery.

2. The method for treating a battery according to claim 1, wherein the method for treating the battery has a protective layer forming step of forming the protective layer on the surface of the Al terminal before the immersion step.

3. The battery has an electrode body, an exterior body covering the electrode body, and the Al terminal electrically connected to the electrode body and partially exposed from the exterior body. The method for treating a battery according to claim 1, wherein the protective layer is formed on the surface of the Al terminal located inside the exterior body.

4. The method for treating a battery according to claim 1, wherein the protective layer is an aluminum oxide layer.

5. The method for treating a battery according to claim 4, wherein the aluminum oxide layer is a boehmite layer.

6. The method for treating a battery according to claim 1, wherein the protective layer is a conductive resin layer.

7. The method for treating a battery according to claim 1, wherein the protective layer is a plating layer.

8. A battery containing an Al terminal is immersed in a treatment liquid, and has an immersion step of reducing the voltage of the battery by an external short circuit through the treatment liquid. The treatment liquid contains water and a supporting salt. The material of the Al terminal is an Al—Mg—Si based alloy or an Al—Ni clad material, and a method for treating a battery.

9. A battery containing an Al terminal, wherein the Al terminal has a protective layer on at least a part of its surface for suppressing elution of the Al terminal into the treatment liquid.

10. The battery has an electrode body, an exterior body covering the electrode body, and the Al terminal electrically connected to the electrode body and partially exposed from the exterior body. The battery according to claim 9, wherein, when viewed in the thickness direction, the protective layer is selectively formed in a region including an end portion of the Al terminal on the exterior body side.

11. A battery containing an Al terminal, wherein the material of the Al terminal is an Al—Mg—Si based alloy or an Al—Ni clad material.

12. The battery according to claim 9 or claim 11 has a laminate type exterior body.

13. The battery according to claim 9 or claim 11 is a solid battery.

Images