Battery component processing method

Abstract

Provided is a method that is for treating a battery member containing a sulfide, and that is capable of effectively removing hydrogen sulfide generated when the battery member is brought into contact with a treatment liquid.　The method is for treating a battery member containing lithium metal and a sulfide, the method comprising: a nitrification step S1 for bringing the battery member into contact with nitrogen gas to obtain a substance containing lithium nitride and the sulfide; and a treatment step S2 for bringing the substance containing lithium nitride and the sulfide into contact with a treatment liquid containing water.

Description

[Technical Field]

[0001] The present invention relates to a method for treating battery components. [Background technology]

[0002] Batteries such as lithium-ion secondary batteries are used as power sources in hybrid vehicles and electric vehicles. In recent years, a rapid increase in used automotive batteries and batteries discarded as defective products during battery manufacturing is expected. These batteries contain valuable materials such as lithium. To make effective use of resources, methods for recovering valuable materials from such batteries have been proposed.

[0003] For example, Patent Document 1 describes a technique for recovering metallic lithium by converting metallic lithium having unwanted formations formed on its surface into lithium chloride, melting the resulting lithium chloride, and electrolyzing the resulting lithium chloride. Patent Document 1 describes that this method makes it possible to recover metallic lithium even from metallic lithium having unwanted formations formed on its surface.

[0004] Patent Document 2 describes a method for treating battery components containing at least a sulfide solid electrolyte material having Li (lithium) and P (phosphorus), which includes a step of generating hydrogen sulfide and dissolving Li in the treatment solution by contacting the battery components with a treatment solution containing water, a step of recovering a positive electrode active material from the treatment solution, and a step of drying the treatment solution from which the positive electrode active material has been recovered to recover a Li compound. Patent Document 2 describes that the positive electrode active material and the sulfide solid electrolyte material can be efficiently separated, and that Li contained in the positive electrode active material and the sulfide solid electrolyte material can be efficiently recovered. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-87404 [Patent Document 2] Patent No. 5062262 Summary of the Invention [Problem to be solved by the invention]

[0006] When recovering metallic lithium from battery components, the battery components are brought into contact with a treatment solution to dissolve the lithium contained in the battery components and separate it from insoluble components such as the active material contained in the battery components.

[0007] However, if the battery components contain sulfides, hydrogen sulfide is generated when the battery components are brought into contact with the treatment solution, which requires the provision of equipment for recovering the generated hydrogen sulfide, resulting in high maintenance costs and reduced productivity.

[0008] An object of the present invention is to provide a method for treating battery components that can effectively suppress the generation of hydrogen sulfide when sulfide-containing battery components are brought into contact with a treatment solution. [Means for solving the problem]

[0009] As a result of intensive research, the present inventors have found that the above-mentioned problems can be solved by contacting a battery component with nitrogen gas to obtain a substance containing lithium nitride and sulfide, and then contacting the substance with a treatment solution, thereby completing the present invention.

[0010] The present invention provides a method for treating a battery component containing lithium metal and sulfide, the method comprising: a nitriding 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 liquid containing water.

[0011] This makes it possible to effectively suppress the generation of hydrogen sulfide when the sulfide-containing battery component is brought into contact with the treatment liquid.

[0012] The battery component may further contain a ternary positive electrode material, and the treatment liquid may be an alkaline aqueous solution.

[0013] The battery member may further contain copper metal, stainless steel, and aluminum, and the treatment liquid may be an alkaline aqueous solution.

[0014] The battery component may be derived from a solid-state battery containing lithium metal and a solid electrolyte containing a sulfide. [Effects of the Invention]

[0015] According to the present invention, even when a battery component containing sulfide is brought into contact with a treatment solution, generation of hydrogen sulfide can be effectively suppressed. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a process diagram showing an example of the flow of a method for treating battery components of a solid-state battery. DETAILED DESCRIPTION OF THE INVENTION

[0017] Specific embodiments of the present invention will be described in detail below, but the present invention is not limited to the following embodiments and can be implemented with appropriate modifications within the scope of the object of the present invention.

[0018] 1. Overview The method for treating a battery component of the present invention is a method for treating a battery component containing lithium metal and sulfide, and includes at least a nitriding 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.

[0019] In this way, by converting the lithium metal contained in the battery components into lithium nitride prior to the treatment step in which the battery components are brought into contact with the treatment solution, it is possible to effectively suppress the generation of hydrogen sulfide that occurs during the treatment step.

[0020] As one embodiment of the method for treating battery components of the present invention, a method for recovering lithium metal by removing battery components from a solid-state battery (all-solid-state battery) containing lithium metal and a solid electrolyte containing sulfide and treating the battery components will be described below. Note that the battery used in the method for treating battery components of the present invention is not limited to solid-state batteries (all-solid-state batteries) containing a solid electrolyte, but may be a battery containing an electrolytic solution as the electrolyte, or a polymer battery in which an electrolytic solution is impregnated in a polymer gel. Furthermore, the battery used in the method for treating battery components of the present invention is not limited to batteries containing sulfide in the electrolyte, but may be a battery in which sulfide is contained in a battery component (e.g., an electrode, a separator, etc.) other than the electrolyte.

[0021] 2. Method for processing battery components of solid-state batteries As shown in FIG. 1, the method for treating battery components according to this embodiment includes an extraction step S1 of extracting battery components containing lithium metal and a solid electrolyte containing sulfide from a solid-state battery, a nitriding step S2 of contacting the battery components with nitrogen gas to obtain a substance containing lithium nitride and sulfide, a treatment step S3 of contacting the substance containing lithium nitride and sulfide with a treatment liquid containing water, and a recovery step S4 of recovering valuable materials.

[0022] 2-1. Removal process S1 In the removal step S1, a battery component containing lithium metal and an electrolyte containing sulfide is removed from the solid-state battery. Since the battery stack constituting the solid-state battery is generally packaged in a package made of a laminate film or the like, the battery stack containing valuable resources is opened and removed from the package.

[0023] Although this unloading step S1 may be performed in the air, it is preferable to perform the unloading step of unloading the battery stack in a nitrogen atmosphere so as to minimize contact of the battery components containing lithium metal and a sulfide-containing solid electrolyte with gases other than nitrogen gas. The preferred range of the nitrogen gas concentration in the atmosphere gas at this time is the same as the preferred range of the nitrogen gas concentration in the nitriding step S2 described below.

[0024] The battery stack that constitutes the solid-state 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.

[0025] The positive electrode layer includes, for example, a positive electrode current collector and a positive electrode active material thereon. The positive electrode layer may include a binder, a conductive additive, an electrolyte, etc. The binder, conductive additive, electrolyte, etc. are not particularly limited, and any substance known as an electrode material for a secondary battery can be used.

[0026] The positive electrode active material is not particularly limited, and a material known as a positive electrode active material for secondary batteries can be used. Examples of the positive electrode active material include layered positive electrode active material particles such as LiCoO2, LiNiO2, LiNiO2 / LiCoO2 / LiMn2O4 (ternary positive electrode material), LiVO2, and LiCrO2, LiMn2O4, Li(Ni 0.25 Mn 0.75 )2O4, LiCoMnO4, Li2NiMn3O8, and other spinel-type positive electrode active materials; LiCoPO4, LiMnPO4, LiFePO4, and other olivine-type positive electrode active materials can be used.

[0027] Among these, it is preferable to use a ternary positive electrode material such as LiNiO2 / LiCoO2 / LiMn2O4 as the positive electrode active material. By using a ternary positive electrode material as the positive electrode active material, the ternary positive electrode material is inevitably contained in the battery component to be treated. Because the ternary positive electrode material is insoluble in an alkaline aqueous solution, by contacting the object to be treated with a treatment solution that is an alkaline aqueous solution, only the lithium nitride is selectively dissolved, making it possible to selectively recover the ternary positive electrode material.

[0028] The positive electrode current collector is not particularly limited, and any known material for a positive electrode current collector of a secondary battery can be used. Examples of the positive electrode current collector include aluminum and stainless steel. The aluminum and stainless steel may be formed into a foil. In addition to the above, a conductive carbon sheet (e.g., a graphite sheet or a CNT sheet) may also be used.

[0029] The negative electrode layer includes, for example, a negative electrode current collector and a negative electrode active material thereon. The negative electrode layer may also include a binder, a conductive additive, an electrolyte, etc. The binder, conductive additive, electrolyte, etc. are not particularly limited, and any known material may be used as an electrode material for secondary batteries.

[0030] The negative electrode active material contains lithium metal, because the use of a material containing lithium metal as the negative electrode active material inevitably results in the lithium metal to be recovered being contained in the battery components to be treated.

[0031] The negative electrode active material may contain a negative electrode active material other than lithium metal. Examples of the negative electrode active material other than lithium metal include lithium titanate (Li4Ti5O 12 transition metal oxides such as TiO2, Nb2O3 and WO3, metal sulfides, metal nitrides, carbon materials such as graphite, soft carbon and hard carbon, and metallic indium and lithium alloys.

[0032] The negative electrode current collector is not particularly limited, and materials known for use as negative electrode current collectors in solid-state batteries can be used. Among these, the negative electrode current collector preferably contains at least one selected from the group consisting of copper metal, stainless steel, and aluminum, and more preferably contains at least one selected from the group consisting of copper metal and stainless steel. Using a negative electrode current collector containing at least one selected from the group consisting of copper metal, stainless steel, and aluminum inevitably results in the battery component to be treated containing copper metal, stainless steel, or aluminum. Since copper metal and stainless steel are insoluble in alkaline aqueous solutions, and aluminum is only soluble in strong alkaline aqueous solutions, contacting the material to be treated with a treatment solution that is an alkaline aqueous solution with a predetermined pH range allows selective dissolution of only lithium nitride, and selective recovery of copper metal, stainless steel, and aluminum as insoluble materials.

[0033] The solid electrolyte layer includes a sulfide-containing solid electrolyte. Examples of sulfide-containing solid electrolytes include those containing Li, S, and a third component A. Examples of the third component A include at least one selected from the group consisting of P, Ge, B, Si, I, Al, Ga, and As. In particular, in the present invention, the sulfide solid electrolyte material is preferably a compound containing Li2S and a sulfide MS other than Li2S. Specific examples include a Li2S-P2S5 compound, a Li2S-SiS2 compound, and a Li2S-GeS2 compound. The solid electrolyte layer may also contain a solid electrolyte other than a sulfide. Examples of solid electrolytes other than sulfides include oxide-based solid electrolytes, nitride-based solid electrolytes, and halide-based solid electrolytes.

[0034] 2-2.Nitriding process S2 In the nitriding step S2, the battery component containing lithium metal derived from the negative electrode active material and sulfide derived from the solid electrolyte layer is brought into contact with nitrogen gas, whereby the lithium metal and the nitrogen gas react to obtain a substance containing lithium nitride.

[0035] By bringing a substance containing lithium nitride into contact with a treatment liquid containing water in a treatment step described below, ammonia ions are generated, making it possible to effectively suppress the generation of hydrogen sulfide.

[0036] One method for contacting the battery components with nitrogen gas is to place the battery components in a sealed container filled with nitrogen gas for a predetermined period of time, where the nitrogen gas concentration in the ambient gas in the sealed container is preferably 90% by volume or more, more preferably 95% by volume or more, and even more preferably 99% by volume or more.

[0037] The temperature at which the battery components are brought into contact with nitrogen gas 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.

[0038] The pressure (nitrogen partial pressure) when the battery components are 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.

[0039] The time for which the battery components are brought into contact with nitrogen gas is not particularly limited, but is preferably from 1 hour (h) to 100 hours (h), and more preferably from 8 hours (h) to 24 hours (h).

[0040] 3-3. Treatment process In the treatment step S3, the substance containing lithium nitride and sulfide is brought into contact with a treatment solution containing water, thereby dissolving the lithium nitride in the treatment solution and separating it from insoluble components such as the active material contained in the battery component.

[0041] Specifically, sulfide ions (S 2- ) reacts with water in the treatment solution as shown in the following formula (1) to form sulfur dioxide ions (SO2 2- ) and reacts with water to produce sulfate ions (SO4 2-On the other hand, lithium nitride (Li3N) reacts with water in the treatment solution to produce ammonium ions (NH 4+ ) is generated. Then, the sulfate ions (SO4 2- ) and the ammonium ion (NH 4+ ) reacts as shown in equation (4) to produce ammonium sulfate ((NH4)2SO4).

[0042] S 2- +2H2O → SO2 2- +2H2···(1) SO2 2- +2H2O → SO4 2- +2H2···(2) Li3N+4H2O → 3Li + +4OH - +NH4 + ···(3) SO4 2- +2NH4 + → (NH4)2SO4 (4)

[0043] In this way, the lithium metal contained in the battery material is converted into lithium nitride in advance by the nitriding step S2, and the lithium nitride is brought into contact with the treatment solution to generate ammonium ions (NH 4+ ) which reacts with sulfide ions derived from sulfides, thereby effectively suppressing the generation of hydrogen sulfide.

[0044] The treatment liquid has a function of dissolving lithium nitride contained in the battery components. Such a treatment liquid contains water, and may contain a protic organic solvent such as an alcohol or a ketone together with water.

[0045] In particular, when the battery component contains a ternary positive electrode material derived from the positive electrode active material of a solid-state battery, or when it contains copper metal, stainless steel, or aluminum derived from a current collector of a solid-state battery, the treatment liquid is preferably an alkaline aqueous solution. Because ternary positive electrode materials, copper metal, and stainless steel do not dissolve in alkaline aqueous solutions, and aluminum only dissolves in strong alkaline aqueous solutions, contacting the material to be treated with a treatment liquid that is an alkaline aqueous solution with a predetermined pH range makes it possible to selectively dissolve lithium nitride contained in the material to be treated. Note that, in this specification, an alkaline aqueous solution means one with a pH greater than 7.

[0046] The pH of the treatment solution is preferably 7 or higher, and more preferably 11 or higher. If the substance to be treated contains aluminum derived from a current collector or the like, a strongly alkaline treatment solution will dissolve the aluminum. Therefore, if the substance to be treated contains aluminum, the pH is preferably 14 or lower, and more preferably 13 or lower.

[0047] One example of a method for contacting a substance to be treated with a treatment solution is to immerse a battery component in the treatment solution (immersion method). The immersion method provides a large contact area between the battery component and the treatment solution, allowing for efficient dissolution of lithium nitride (LiN) contained in the substance to be treated. Furthermore, in the case of the immersion method, it is preferable to agitate the treatment solution.

[0048] Another example of a method for contacting a substance to be treated with a treatment liquid is a method in which the treatment liquid is sprayed onto the substance to be treated (spray method). The spray method has the advantage of being more suitable for continuous treatment than the above-mentioned immersion method. Furthermore, by placing the substance to be treated on a filter and spraying the treatment liquid onto the substance, a filtration step can be performed simultaneously. Furthermore, in the present invention, a heated treatment liquid may be brought into contact with a battery component.

[0049] 2-4. Recovery process S4 In the recovery step S4, valuable materials such as lithium metal are recovered. Specifically, the insoluble components and the treatment solution are separated from the mixture of the treatment solution obtained in the treatment step S3 and the substance to be treated, thereby obtaining a treatment solution in which lithium has been dissolved. Specific examples of the method for recovering the insoluble components from the mixture include filtration.

[0050] The insoluble components mainly include positive electrode active materials such as ternary positive electrode materials and metal materials derived from the current collector. The insoluble components may also include conductive materials and negative electrode active materials other than lithium metal. Methods for recovering the positive electrode active material from the insoluble components include, for example, methods that utilize differences in specific gravity, such as air classification, sedimentation classification, and centrifugal classification.

[0051] Lithium can be recovered from the treated solution separated from the mixture. A preferred method for recovering lithium from the treated solution is to use a lithium recovery method (LiSMIC) using an ionic conductor as a lithium separation membrane. Specifically, the treated solution containing dissolved lithium is brought into contact with a recovery solution (pure water) via a lithium separation membrane, and a voltage is applied to transfer lithium ions to the recovery solution, converting the recovery solution into a highly pure lithium hydroxide aqueous solution. Carbon dioxide gas is then blown into the lithium hydroxide aqueous solution to recover lithium in the form of lithium carbonate (Li2CO3). This method allows for a high recovery rate of lithium.

[0052] Another method for recovering lithium from the treatment solution is to remove the solvent from the treatment solution by drying, and then recover the lithium as a lithium compound.

[0053] When aluminum is contained in the treatment solution, it is preferable to remove the aluminum by a conventionally known method and then recover lithium by the above method.

[0054] As described above, the method for treating battery components of the present invention can effectively suppress the generation of hydrogen sulfide even when battery components containing sulfides derived from the electrolyte are brought into contact with a treatment solution, while efficiently recovering valuable resources such as lithium metal.

Claims

1. A method for treating a battery component containing lithium metal and sulfide, comprising: a nitriding step of contacting the battery component with nitrogen gas to obtain a substance containing lithium nitride and sulfide; a treatment step of contacting a substance containing lithium nitride and sulfide with a treatment liquid containing water; Including, Method for processing battery components.

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

3. 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. The method for treating battery components according to claim 1 or 2.

4. The battery component is derived from a solid-state battery containing lithium metal and a solid electrolyte containing a sulfide. The method for treating battery components according to claim 1 or 2.

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