Method for processing battery component

Abstract

Provided is a method for treating a battery member, which can effectively remove hydrogen sulfide generated when a sulfide-containing battery member is brought into contact with a treatment liquid. A method for processing a battery member containing a lithium metal and a sulfide, the method comprising: a nitriding step (S1) in which the battery member is brought into contact with nitrogen gas to obtain a substance containing a lithium nitride and a sulfide; and a treatment step (S2) in which the substance containing the lithium nitride and the sulfide is brought into contact with a treatment liquid containing water.

Description

Technical Field

[0001] The invention relates to a method for processing battery components. Background Art

[0002] Lithium-ion secondary batteries and other batteries are used as power sources for hybrid vehicles and pure electric vehicles. In recent years, the number of batteries used in vehicles or batteries discarded as defective during battery manufacturing is expected to increase dramatically. In addition, valuables such as lithium are contained in such batteries. In order to effectively utilize resources, a method for recovering valuables from such batteries has been proposed.

[0003] For example, Patent Document 1 describes a technique for recovering metallic lithium by electrolyzing metallic lithium having an unwanted formation formed on its surface into lithium chloride and melting the lithium chloride. Patent Document 1 describes that even metallic lithium having an unwanted formation formed on its surface can be recovered by this method.

[0004] In addition, Patent Document 2 describes a method for treating a battery component containing a sulfide solid electrolyte material containing at least Li (lithium) and P (phosphorus), and includes the following steps: generating hydrogen sulfide by contacting the battery component with a treatment solution containing water, and dissolving Li in the treatment solution; recovering the positive electrode active material from the treatment solution; and drying the treatment solution from which the positive electrode active material has been recovered, and recovering the Li compound. Patent Document 2 describes that the positive electrode active material can be separated from the sulfide solid electrolyte material with high efficiency, and that the Li contained in the positive electrode active material and the sulfide solid electrolyte material can be recovered with high efficiency.

[0005] [Prior Technical Literature]

[0006] (Patent Document)

[0007] Patent Document 1: Japanese Patent Application Publication No. 2012-87404

[0008] Patent Document 2: Japanese Patent No. 5062262 Summary of the invention

[0009] [Problems to be solved by the invention]

[0010] When recovering metallic lithium from a battery component, the battery component is brought into contact with a treatment solution, whereby the lithium contained in the battery component is dissolved and separated from insoluble components such as active materials contained in the battery component.

[0011] However, if the battery components contain sulfides, hydrogen sulfide will be generated when the battery components are brought into contact with the treatment liquid, and it is necessary to have a facility for recovering the generated hydrogen sulfide, which makes the maintenance of the facility expensive and reduces productivity.

[0012] An object of the present invention is to provide a method for treating a battery component, which can effectively suppress the generation of hydrogen sulfide when a battery component containing a sulfide is brought into contact with a treatment solution.

[0013] [Technical means to solve the problem]

[0014] The present inventors have conducted intensive studies and have found that the above-mentioned problems can be solved by bringing a battery component into contact with nitrogen gas to obtain a substance containing lithium nitride and sulfide, and bringing the substance into contact with a treatment liquid, thereby completing the present invention.

[0015] The present invention provides a method for treating a battery component, wherein the battery component contains lithium metal and sulfide. The method for treating the battery component comprises: a nitridation step of contacting the battery component with nitrogen gas to obtain a substance containing lithium nitride and sulfide; and a treatment step of contacting the substance containing lithium nitride and sulfide with a treatment solution containing water.

[0016] This can effectively suppress the generation of hydrogen sulfide when the battery component containing sulfide is brought into contact with the treatment liquid.

[0017] Optionally, the battery component further contains a ternary positive electrode material, and the treatment liquid is an alkaline aqueous solution.

[0018] Optionally, the battery component further contains copper metal, stainless steel and aluminum, and the treatment liquid is an alkaline aqueous solution.

[0019] Optionally, the aforementioned battery component is derived from a solid battery containing lithium metal and a solid electrolyte comprising a sulfide.

[0020] (Effects of the Invention)

[0021] According to the present invention, even when a battery component containing a sulfide is brought into contact with a treatment liquid, the generation of hydrogen sulfide can be effectively suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a process diagram showing an example of the flow of a method for processing battery components of a solid battery. DETAILED DESCRIPTION

[0023] Hereinafter, specific embodiments of the present invention will be described in detail, but the present invention is not limited to the following embodiments at all and can be implemented with appropriate modifications within the scope of the purpose of the present invention.

[0024] 1. Summary

[0025] The method for treating a battery component of the present invention is a method for treating a battery component containing lithium metal and sulfide. The method for treating a battery component at least comprises: a nitridation step of contacting the battery component with nitrogen gas to obtain a substance containing lithium nitride and sulfide; and a treatment step of contacting the substance containing lithium nitride and sulfide with a treatment solution containing water.

[0026] By converting lithium metal contained in the battery component into lithium nitride before the treatment step of bringing the battery component into contact with the treatment liquid, the generation of hydrogen sulfide generated in the treatment step can be effectively suppressed.

[0027] Hereinafter, as one embodiment of the method for processing battery components of the present invention, a method is described in which a battery component is taken out from a solid battery (full solid battery) containing lithium metal and a solid electrolyte containing sulfide, and the battery component is processed to recover lithium metal. In addition, the battery used in the method for processing battery components of the present invention is not limited to a solid battery (full solid battery) containing a solid electrolyte, and may be a battery containing an electrolyte as an electrolyte, or may be a polymer battery containing an electrolyte in a polymer gel. In addition, the battery used in the method for processing battery components of the present invention is not limited to a battery containing a sulfide in the electrolyte, and may be a battery containing a sulfide in a battery component (such as an electrode or a separator) other than the electrolyte.

[0028] 2. Processing method of battery components of solid battery

[0029] The processing method of the battery components of this embodiment is as follows Figure 1 As shown, it includes: a taking-out step S1, taking out a battery component containing lithium metal and a solid electrolyte containing sulfide from a solid battery; a nitriding step S2, contacting the battery component with nitrogen to obtain a substance containing lithium nitride and sulfide; a treatment step S3, contacting the substance containing lithium nitride and sulfide with a treatment solution containing water; and a recovery step S4, recovering valuables.

[0030] 2-1. Removal process S1

[0031] In the removal step S1, battery components containing lithium metal and an electrolyte containing sulfide are removed from the solid battery. The battery stack constituting the solid battery is generally packaged in a packaging body composed of a laminate film or the like, so the battery stack containing the valuables is removed from the packaging body by opening it.

[0032] This removal step S1 can be performed in the air, for example, but in order to avoid contact between the battery components containing lithium metal and the solid electrolyte containing sulfide and gases other than nitrogen as much as possible, this removal step of removing the battery stack is also preferably performed in a nitrogen atmosphere. The preferred range of the concentration of nitrogen in the atmospheric gas at this time is the same as the preferred range of the concentration of nitrogen in the nitriding step S2 described later.

[0033] The electrode stack constituting the solid battery includes a positive electrode layer, a negative electrode layer, and a solid electrolyte layer between the positive electrode layer and the negative electrode layer.

[0034] The positive electrode layer, for example, includes a positive electrode current collector and a positive electrode active material on the positive electrode current collector. The positive electrode layer may also include a binder, a conductive additive, an electrolyte, etc. The binder, conductive additive, electrolyte, etc. are not particularly limited, and substances known as electrode materials for secondary batteries can be applied.

[0035] The positive electrode active material is not particularly limited, and a material known as a positive electrode active material for a secondary battery can be used. As the positive electrode active material, for example, layered positive electrode active material particles such as LiCoO2, LiNiO2, LiNiO2 / LiCoO2 / LiMn2O4 (ternary positive electrode material), LiVO2, LiCrO2, etc., LiMn2O4, Li(Ni 0.25 Mn 0.75 )2O4, LiCoMnO4, Li2NiMn3O8 and other spinel positive electrode active materials, LiCoPO4, LiMnPO4, LiFePO4 and other olivine positive electrode active materials, etc.

[0036] Among them, as the positive electrode active material, it is preferred to contain a positive electrode active material that is a ternary positive electrode material such as LiNiO2 / LiCoO2 / LiMn2O4. By using a positive electrode active material that is a ternary positive electrode material as the positive electrode active material, the battery component that is the treatment object will inevitably contain a ternary positive electrode material. The ternary positive electrode material is insoluble in an alkaline aqueous solution, so by contacting the treatment object with a treatment solution that is an alkaline aqueous solution, only lithium nitride can be selectively dissolved, and the ternary positive electrode material can be selectively recovered.

[0037] The positive electrode collector is not particularly limited, and a material known as a positive electrode collector of a secondary battery can be applied. As the positive electrode collector, for example, aluminum, stainless steel, etc. can be cited. For example, the aluminum, stainless steel, etc. can be formed into a foil. In addition to the above, a conductive carbon sheet (for example, a graphite sheet or a carbon nanotube (CNT) sheet) can also be used.

[0038] The negative electrode layer includes, for example, a negative electrode current collector and a negative electrode active material on the negative electrode current collector. In addition, the negative electrode layer may also include a binder, a conductive aid, an electrolyte, etc. The binder, conductive aid, electrolyte, etc. are not particularly limited, and substances known as electrode materials for secondary batteries can be applied.

[0039] The negative electrode active material is a material containing lithium metal. This is because, by using a material containing lithium metal as the negative electrode active material, the battery component to be processed will inevitably contain lithium metal to be recovered.

[0040] In addition, the negative electrode active material may also contain negative electrode active materials other than lithium metal. Examples of negative electrode active materials other than lithium metal include lithium titanate (Li4Ti5O 12 ) and other lithium transition metal oxides, transition metal oxides such as TiO2, Nb2O3 and WO3, metal sulfides, metal nitrides, graphite, carbon materials such as soft carbon and hard carbon, as well as metal indium and lithium alloys.

[0041] The negative electrode collector is not particularly limited, and a substance known as a negative electrode collector for a solid battery can be applied. Among them, the negative electrode collector is preferably a substance containing at least one selected from the group consisting of copper metal, stainless steel and aluminum, and more preferably a substance containing at least one selected from the group consisting of copper metal and stainless steel. By using a substance containing at least one selected from the group consisting of copper metal, stainless steel and aluminum as a negative electrode collector, copper metal, stainless steel or aluminum will inevitably be contained in the battery component that is the object of treatment. Copper metal and stainless steel are insoluble in alkaline aqueous solutions, and aluminum is insoluble if it is not a strong alkaline aqueous solution. Therefore, by contacting the object of treatment with a treatment solution that is an alkaline aqueous solution in a specified pH range, only lithium nitride can be selectively dissolved, and copper metal, stainless steel or aluminum can be selectively recovered as insoluble matter.

[0042] The solid electrolyte layer is a layer containing a solid electrolyte containing a sulfide. As a solid electrolyte containing a sulfide, substances having Li, S and a third component A can be listed. As the third component A, for example, at least one selected from the group consisting of P, Ge, B, Si, I, Al, Ga and As can be listed. Among them, in the present invention, it is preferred that the sulfide solid electrolyte material is a compound using a sulfide MS other than Li2S and Li2S. Specifically, Li2S-P2S5 compounds, Li2S-SiS2 compounds, Li2S-GeS2 compounds, etc. can be listed. In addition, in the solid electrolyte layer, solid electrolytes other than sulfides may also be contained. As solid electrolytes other than sulfides, for example, oxide-based solid electrolytes, nitride-based solid electrolytes, halide-based solid electrolytes, etc. can be listed.

[0043] 2-2. Nitriding step S2

[0044] In the nitriding step S2, the battery component containing lithium metal mainly derived from the negative electrode active material and the sulfide derived from the solid electrolyte layer is brought into contact with nitrogen gas, thereby reacting the lithium metal with the nitrogen gas to obtain a substance containing lithium nitride.

[0045] By bringing the lithium nitride-containing substance into contact with a treatment liquid containing water in the treatment step described later, ammonium ions can be generated, thereby effectively suppressing the generation of hydrogen sulfide.

[0046] As a method for contacting the battery components with nitrogen, there can be cited a method of placing the battery components in a sealed container filled with nitrogen and placing them for a predetermined time. At this time, the concentration of nitrogen in the atmosphere gas in the sealed container is preferably 90 volume % or more, more preferably 95 volume % or more, and further preferably 99 volume % or more.

[0047] The temperature when the battery component is brought into contact with nitrogen is not particularly limited, but is preferably 25° C. or higher and 120° C. or lower, and more preferably 50° C. or higher and 70° C. or lower.

[0048] The pressure (nitrogen partial pressure) when the battery component is brought into contact with nitrogen gas is not particularly limited, but is preferably 10 kPa or more and 1000 kPa or less, and more preferably 100 kPa or less.

[0049] The time for contacting the battery component with nitrogen is not particularly limited, but is preferably 1 hour (h) or more and 100 hours (h) or less, and more preferably 8 hours (h) or more and 24 hours (h) or less.

[0050] 3-3. Processing steps

[0051] In the treatment step S3, the material containing lithium nitride and sulfide is brought into contact with a treatment liquid containing water, thereby dissolving the lithium nitride in the treatment liquid and separating it from insoluble components such as active materials contained in the battery component.

[0052] Specifically, sulfide ions (S 2- ) reacts with water in the treatment solution to generate sulfur dioxide ions (SO2 2- ). Then, as shown in the following formula (2), it reacts with water to generate sulfate ions (SO4 2- On the other hand, lithium nitride (Li3N) reacts with water in the treatment solution to generate ammonium ions (NH 4+ ). In addition, the sulfate ions (SO4 2- ) and the ammonium ion (NH4+ ) reacts as shown in formula (4) to generate ammonium sulfate ((NH4)2SO4).

[0053] S 2- +2H2O→SO2 2- +2H2···(1)

[0054] SO2 2- -+2H2O→SO4 2- +2H2···(2)

[0055] Li3N+4H2O→3Li + +4OH - +NH4 + ···(3)

[0056] SO4 2- +2NH4 + →(NH4)2SO4···(4)

[0057] In this way, the lithium metal contained in the battery material is converted into lithium nitride in advance by the nitridation step S2, and ammonium ions (NH 4+ ) and react with sulfide ions derived from sulfides, thereby effectively suppressing the generation of hydrogen sulfide.

[0058] The treatment liquid has the function of dissolving the lithium nitride contained in the battery component. Such a treatment liquid is a substance containing water, and may contain a protic organic solvent such as alcohol or ketone together with water.

[0059] In particular, in the case where the battery component contains a ternary positive electrode material of a positive electrode active material derived from a solid battery, or contains copper metal, stainless steel or aluminum from a current collector of a solid battery, the treatment liquid is preferably an alkaline aqueous solution. The ternary positive electrode material, copper metal or stainless steel is insoluble in an alkaline aqueous solution, and aluminum is also insoluble if it is not a strong alkaline aqueous solution. Therefore, by contacting the treatment object with the treatment liquid of an alkaline aqueous solution in a specified pH range, the lithium nitride contained in the substance of the treatment object can be selectively dissolved. In addition, in this specification, an alkaline aqueous solution means a pH exceeding 7.

[0060] The pH of the treatment liquid is preferably above 7, more preferably above 11. In addition, when the material to be treated contains aluminum originating from a current collector or the like, the treatment liquid will dissolve the aluminum if it is strongly alkaline. Therefore, when the material to be treated contains aluminum, the pH is preferably set to below 14, more preferably below 13.

[0061] As an example of a method for bringing a substance to be treated into contact with a treatment liquid, a method of immersing a battery component in a treatment liquid (immersion method) can be cited. In the immersion method, since the contact area between the battery component and the treatment liquid is large, lithium nitride (Li3N) contained in the substance to be treated can be dissolved efficiently. Furthermore, in the case of the immersion method, it is preferred to stir the treatment liquid.

[0062] As another example of a method for contacting a substance as a treatment object with a treatment liquid, a method (spraying method) of spraying a treatment liquid onto a substance as a treatment object can be cited. The spraying method has the advantage of being suitable for continuous treatment compared to the above-mentioned immersion method. In addition, the filtering process can be performed simultaneously by arranging a substance as a treatment object on a filter and spraying a treatment liquid onto the substance. In addition, in the present invention, the heated treatment liquid can also be brought into contact with the battery components.

[0063] 2-4. Recovery process S4

[0064] In the recovery step S4, valuable materials such as lithium metal are recovered. Specifically, insoluble components are separated from the treatment liquid from the mixture of the treatment liquid obtained in the above-mentioned treatment step S3 and the substance as the treatment object, and the treatment liquid in which lithium is dissolved is obtained. As a method for recovering insoluble components from the liquid in the mixture, a filtration method can be specifically cited.

[0065] The insoluble components mainly include positive electrode active materials such as ternary positive electrode materials or metal materials derived from collectors. In addition, the insoluble components may also include conductive materials or negative electrode active materials other than lithium metal. As a method for recovering positive electrode active materials from the insoluble components, for example, a method using a specific gravity difference can be cited, specifically, wind classification, sedimentation classification, centrifugal classification, etc.

[0066] Lithium can be recovered from the treatment solution separated from the mixture. As a method for recovering lithium from the treatment solution, it is preferred to use a lithium recovery method (LiSMIC) using an ion conductor as a lithium separation membrane for recovery. Specifically, it is a method in which a treatment solution in which lithium is dissolved is contacted with a recovery solution (pure water) via a lithium separation membrane, a voltage is applied to move lithium ions to the recovery solution side, and the recovery solution is made into a high-purity lithium hydroxide aqueous solution, and carbon dioxide gas is blown into the lithium hydroxide aqueous solution, thereby using lithium carbonate (Li2CO 3) Thus, lithium can be recovered at a high recovery rate.

[0067] Another method for recovering lithium from the treatment liquid is to remove the solvent of the treatment liquid by drying and recover the lithium as a lithium compound.

[0068] When aluminum is contained in the treatment liquid, it is preferred to remove the aluminum by a conventionally known method and then recover lithium by the above-mentioned method.

[0069] As described above, the battery component treatment method of the present invention can effectively suppress the generation of hydrogen sulfide and efficiently recover valuable substances such as lithium metal even when the battery component containing sulfide derived from the electrolyte is brought into contact with the treatment solution.

Claims

1. A method for treating a battery component, wherein the battery component contains lithium metal and sulfide, and the method for treating the battery component comprises: A nitridation step of contacting the battery component with nitrogen to obtain a material containing lithium nitride and sulfide; and, In the treatment step, the material containing lithium nitride and sulfide is brought into contact with a treatment liquid containing water.

2. The method for processing battery components according to claim 1, wherein: The battery component also contains a ternary positive electrode material. The treatment liquid is an alkaline aqueous solution.

3. The method for processing battery components according to claim 1 or 2, wherein: The battery component further contains at least one selected from the group consisting of copper metal, stainless steel and aluminum. The treatment liquid is an alkaline aqueous solution.

4. The method for processing battery components according to claim 1 or 2, wherein: The battery component is derived from a solid battery containing lithium metal and a solid electrolyte comprising a sulfide.

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