Metallic lithium manufacturing device and metallic lithium manufacturing method

Abstract

To manufacture metallic lithium further easily.SOLUTION: A metallic lithium manufacturing device comprises a deposition electrode that comes into contact with a non-aqueous electrolyte and deposits metallic lithium, a counter electrode that comes into contact with an aqueous electrolyte, contains electrode material containing lithium and is opposed to the deposition electrode, an ionic conductor that intervenes between the deposition electrode and the counter electrode and conducts lithium ions while separating the non-aqueous electrolyte and the aqueous electrolyte, a control unit that causes metallic lithium to be deposited on the deposition electrode from the lithium on the counter electrode side by applying current between the deposition electrode and the counter electrode.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present specification discloses an apparatus for producing metallic lithium and a method for producing metallic lithium. [Background technology]

[0002] Currently, with the global shift to electric vehicles (EVs), the demand for lithium-ion batteries is rapidly increasing, and there is an urgent need to develop recycling technology for used lithium-ion batteries. However, among the valuable elements used in lithium-ion batteries, lithium is an element that is difficult to recover. Current methods for recycling Li-ion batteries can be broadly divided into dry methods, in which lithium is separated by oxidation-reduction and melting, and wet methods, in which lithium is extracted and separated by precipitation or solvents. In the dry method, lithium is oxidized and incorporated into slag, so in order to recover lithium, it must be extracted from the slag. Li 2 Basic Li compounds such as O and LiOH have high solubility in water, whereas LiF and LiPO 4 The solubility of acidic lithium compounds such as these in water is very low. Therefore, in order to recover lithium, it is necessary to prepare a slag made of highly basic lithium compounds. Currently, lithium recovery is not performed using the dry method.

[0003] On the other hand, in the wet method, Li can only be recovered by extraction at high pH, ​​so a method is used in which a large amount of sodium carbonate is added to generate lithium carbonate and then lithium is recovered. The lithium recovery rate by this method is about 80-90%, which is low compared to other valuable metals (Mn: 94-99%, Ni: 91-99%, Co: 95-99%) (see Non-Patent Document 1). In addition, Li 2 CO 3 The process of evaporating water during recovery consumes energy and produces a large amount of waste liquid, which poses a high environmental burden.

[0004] As a method for producing metallic lithium, for example, one has been proposed that includes an anode compartment containing an aqueous solution of an alkali metal salt, a cathode compartment, and a solid electrolyte separating the anode compartment and the cathode compartment, and the surface of the solid electrolyte in contact with the anode compartment and / or the surface of the solid electrolyte in contact with the cathode compartment has at least one ion-conducting layer (see, for example, Patent Document 1). With this production apparatus, lithium dissolved in the aqueous solution can be extracted as metallic lithium. As such a production apparatus, for example, one has been proposed that performs electrolysis between an anode in contact with a molten composition containing a lithium salt and a cathode separated from the molten composition by a solid electrolyte capable of conducting lithium ions (see, for example, Patent Document 2). With this production apparatus, metallic lithium can be extracted from a molten composition containing a low concentration of lithium salt. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Special Publication No. 2003-507581 [Patent Document 2] Special Publication No. 2022-515439 [Non-patent literature]

[0006] [Non-Patent Document 1] Environ. Sci. Technol. 2023, 57, 4591-4597 Summary of the Invention [Problem to be solved by the invention]

[0007] However, in the manufacturing apparatuses of Patent Documents 1 and 2, lithium ions dissolved in an aqueous solution or a molten composition is used as a supply source of metallic lithium, but other supply sources are not taken into consideration. For example, a positive electrode active material is an example of a lithium source for a lithium secondary battery, but when manufacturing metallic lithium from such an electrode material, it is necessary to dissolve it in an aqueous solution or melt it at a high temperature, which is troublesome. Thus, in the manufacture of metallic lithium, it has been desired to manufacture metallic lithium more easily.

[0008] The present disclosure has been made in consideration of the above problems, and has as its main object to provide an apparatus for producing metallic lithium and a method for producing metallic lithium, which can more easily produce metallic lithium. [Means for solving the problem]

[0009] As a result of intensive research to achieve the above-mentioned object, the inventors have found that metallic lithium can be more easily deposited on the deposition electrode by using a non-aqueous solvent for the deposition electrode, placing an electrode material on the counter electrode and using an aqueous solvent, and applying a predetermined current, and have thus completed the invention disclosed in this specification.

[0010] That is, the metallic lithium production apparatus of the present disclosure is An apparatus for producing metallic lithium, comprising: a deposition electrode on which metallic lithium is deposited in contact with a non-aqueous electrolyte; a counter electrode that is in contact with an aqueous electrolyte and contains a lithium-containing electrode material and faces the deposition electrode; an ion conductive medium interposed between the deposition electrode and the counter electrode, which separates the nonaqueous electrolyte solution from the aqueous electrolyte solution and conducts lithium ions; a control unit that applies a current between the deposition electrode and the counter electrode to deposit metallic lithium from the lithium on the counter electrode side onto the deposition electrode; It is equipped with the following:

[0011] The method for producing metallic lithium according to the present disclosure includes the steps of: A method for producing metallic lithium comprising: a deposition electrode in contact with a non-aqueous electrolyte solution and on which metallic lithium is deposited; a counter electrode in contact with an aqueous electrolyte solution and containing an electrode material containing lithium, the counter electrode facing the deposition electrode; and an ion conductive medium interposed between the deposition electrode and the counter electrode, separating the non-aqueous electrolyte solution from the aqueous electrolyte solution and conducting lithium ions, a deposition step of applying a current between the deposition electrode and the counter electrode to deposit metallic lithium from the lithium on the counter electrode; It includes. Effect of the Invention

[0012] The present disclosure allows metallic lithium to be produced more easily. The reason for obtaining such an effect is presumed to be as follows. For example, in this metallic lithium production apparatus, the electrode material of a lithium secondary battery can be used as a supply source for the counter electrode as it is. In addition, since an aqueous electrolyte is used for the counter electrode, it is easy to handle. Therefore, in this metallic lithium production apparatus and method for producing metallic lithium, metallic lithium can be obtained more easily. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is an explanatory diagram illustrating an example of an apparatus 10 for producing metallic lithium according to the present disclosure. [Diagram 2] Photograph of electrode material as a source of lithium. [Diagram 3] An explanatory diagram of the voltage change of a cell using an LFP electrode as a power source. [Figure 4] A graph showing the relationship between current density and capacity change in the electrolysis reaction of an LFP electrode cell. [Diagram 5] A graph showing the relationship between current density and plateau voltage change of an LFP electrode cell. [Figure 6] XRD patterns of the LFP electrode before and after electrolysis in Experimental Example 7. [Figure 7] A graph showing the relationship between current density and the change in the proportion of the Fe(PO4) phase in the LFP electrode active material. [Figure 8]Photograph of deposits on Cu foil after electrolysis in Experimental Example 5. [Figure 9] XRD pattern of Cu foil after electrolysis in Experimental Example 5. [Figure 10] Voltage change during electrolysis of the cell of Experimental Example 14. [Figure 11] XRD patterns of NCM622 electrode before and after electrolysis in Experimental Example 14. [Figure 12] XRD pattern of Cu foil after electrolysis in Example 14. [Figure 13] XRD patterns of the LFP electrode before and after electrolysis of Example 33. [Figure 14] Photograph of deposits on Cu foil after electrolysis in Example 33. [Figure 15] XRD pattern of Cu foil after electrolysis in Example 33. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] (Metal lithium manufacturing equipment) The metallic lithium manufacturing apparatus described in this embodiment includes a storage unit, a deposition electrode, a non-aqueous electrolyte, a counter electrode, an aqueous electrolyte, an ion-conducting medium, and a control unit. The deposition electrode is an electrode that contacts the non-aqueous electrolyte and deposits metallic lithium. The counter electrode is an electrode that contacts the aqueous electrolyte and contains an electrode material containing lithium, and faces the deposition electrode. The ion-conducting medium is interposed between the deposition electrode and the counter electrode and conducts lithium ions while separating the non-aqueous electrolyte from the aqueous electrolyte. The control unit applies a current between the deposition electrode and the counter electrode to deposit lithium on the counter electrode as metallic lithium.

[0015] The electrode materials serving as the lithium source include the positive and negative electrodes of a lithium secondary battery, among which the positive electrode is preferred. Examples of the lithium secondary battery include a lithium-ion battery in which the negative electrode occludes and releases lithium, a lithium secondary battery in which the negative electrode is lithium metal or a lithium alloy, and a hybrid capacitor. The electrode material may be used as it is as the electrode material of the lithium secondary battery, or may be used as a fragmented electrode obtained by cutting the electrode material, or may be used as black mass as an active material concentrate produced in the recycling process of the lithium secondary battery. The active material serving as the lithium source is preferably a positive electrode active material, and examples of the positive electrode active material as the lithium source include sulfides containing a transition metal element and composite oxides containing lithium and a transition metal element. Specifically, TiS 2 、TiS 3 、MoS 3 、FeS 2 and other transition metal sulfides, with the basic composition formula Li (1-x) MnO 2 (0 < x < 1, etc., the same below) or Li (1-x) Mn 2 O 4 and other lithium manganese composite oxides, with the basic composition formula Li (1-x) CoO 2 and other lithium cobalt composite oxides, with the basic composition formula Li (1-x) NiO 2 and other lithium nickel composite oxides, with the basic composition formula Li (1-x) Ni a Co b Mn c O 2 (a + b + c = 1) and other lithium nickel cobalt manganese composite oxides, with the basic composition formula LiV 2 O 3 and other lithium vanadium composite oxides, with the basic composition formula V 2 O 5 and other transition metal oxides can be used. In addition, examples of the lithium source include lithium iron phosphate (LiFePO 4 : LFP). Specifically, the lithium source includes LFP, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3O 2 (NCM111), LiNi 0.5 Co 0.3 Mn 0.2 O 2 (NCM532), LiNi 0.6 Co 0.2 Mn 0.2 O 2 (NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811), LiNi 0.5 Mn 1.5 O 4 , LiMn 2 O 4 The term "basic composition formula" means that other elements may be included.

[0016] The storage section is a member that stores the deposition electrode, the counter electrode, and the ion-conducting medium. The storage section is made of a material that is insulating and stable at the temperature and potential during the deposition of metallic lithium, such as a resin or ceramic. The storage section is separated into a cathode compartment and an anode compartment by the ion-conducting medium. The cathode compartment stores the deposition electrode and a non-aqueous electrolyte. The anode compartment stores the counter electrode and an aqueous electrolyte. The storage section may be such that the anode compartment is open to the atmosphere. When the storage section is open to the atmosphere, it is preferable because it is easy to take out and put in the electrode material, which is a lithium supply source.

[0017] The deposition electrode is a cathode on which metallic lithium is deposited. The deposition electrode is preferably made of a conductive material that does not react with lithium, i.e., does not form an alloy with lithium, and is easy to separate metallic lithium from. For example, the deposition electrode is preferably made of at least one of copper and nickel. Alternatively, the deposition electrode may be made of metallic lithium or a lithium alloy, or may be made of a noble metal such as Pt or Au. The deposition electrode is preferably in the form of a foil or a plate. The deposition electrode may be housed in a cathode compartment together with a non-aqueous electrolyte, for example. When the deposition of metallic lithium reaches a sufficient thickness, the deposition electrode is taken out of the cathode compartment, and the metallic lithium is separated.

[0018] The non-aqueous electrolyte is preferably one that conducts lithium and has a Li-containing salt dissolved therein. Examples of the non-aqueous electrolyte include non-aqueous solvents such as ethylene carbonate (EC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), 1,3-dioxolane (DOL), and dimethoxyethane (DME). The Li-containing salt may be, for example, the same substance as the supporting salt of a lithium secondary battery, such as LiPF 6 , LiBF 4 , LiAsF 6 , LiCF 3 SO 3 , LiN(CF 3 SO 2 ) 2 , LiC(CF 3 SO 2 ) 3 , LiSbF 6 , LiSiF 6 , LiAlF 4 , LiSCN, LiClO 4 , LiCl, LiF, LiBr, LiI, LiAlCl 4 Among these, LiPF 6 , LiBF 4 , LiAsF 6 , LiClO 4 and inorganic salts such as LiCF 3 SO 3 , LiN(CF 3SO 2 ) 2 , LiC(CF 3 SO 2 ) 3 Among these, the Li-containing salt is lithium hexafluorophosphate (LiPF 6 ), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), etc. are preferred. The concentration of the Li-containing salt is, for example, preferably 0.01 mmol / L (mM) or more, more preferably 0.1 mM or more, and may be 1 mM or more. The concentration is preferably 4 M or less, more preferably 2 M or less, and may be 1 M or less.

[0019] The counter electrode is adjacent to an electrode material of a lithium secondary battery, which is a source of metallic lithium. The counter electrode may be biased toward the ion conductive medium side in a state in which the electrode material is disposed on the ion conductive medium side as long as it can ensure electrical conductivity with the lithium source. This counter electrode is preferably made of at least one of stainless steel and aluminum. The counter electrode may be a carbon electrode containing carbon. The counter electrode may be shaped as a plate, mesh, or porous body. When biased toward the electrode material as a lithium source, the counter electrode is preferably shaped as a mesh or porous body so that excess aqueous electrolyte is discharged from between the counter electrode and the ion conductive medium.

[0020] The aqueous electrolyte is an electrolyte in which lithium ions diffuse. On the counter electrode side, an aqueous electrolyte that is inexpensive and has a low environmental impact can be used instead of an expensive non-aqueous electrolyte. The aqueous electrolyte of the counter electrode preferably contains cations and anions. This aqueous electrolyte preferably contains, for example, lithium nitrate, lithium sulfate, lithium chloride, lithium hydroxide, lithium carboxylate, etc. dissolved therein. In the aqueous electrolyte, the concentration of cations and anions is preferably 0.01 mM or more, more preferably 0.1 mM or more, and may be 1 mM or more. Also, this concentration is preferably 10 M or less, more preferably 5 M or less, and may be 2 M or less. Further, this aqueous electrolyte may be water that does not contain a supporting salt such as the above-mentioned lithium salt. That is, in the aqueous electrolyte, the initial concentration of cations and anions may be 0 mM or more. Such liquids include, for example, distilled water, pure water, ultrapure water, etc. Even if a supporting salt is not added to the aqueous electrolyte, after immersing the electrode as a source of lithium, an aqueous electrolyte containing lithium ions is formed by the lithium salt eluted from the electrode, and thus metallic lithium can be produced using this.

[0021] The ion conduction medium may be a plate-like body that prevents short circuit between the deposition electrode and the counter electrode. This ion conduction medium is preferably a solid electrolyte. The solid electrolyte may be, for example, a garnet-type oxide containing at least Li, La, and Zr. This solid electrolyte has a basic composition of Li 7.0+x-y (La 3-x ,A x )(Zr 2-y ,T y )O 12 and may be of this form. However, A is one or more of Sr and Ca, T is one or more of Nb and Ta, and it satisfies 0 < x ≦ 1.0 and 0 < y < 0.75. Alternatively, the solid electrolyte has a basic composition (Li 7-3z+x-y M z )(La 3-x A x )(Zr 2-y T y )O 12 or, (Li 7-3z+x-y M z)(La 3-x A x )(Y 2-y T y )O 12 In the formula, the element M may be one or more of Al and Ga, the element A may be one or more of Ca and Sr, and T may be one or more of Nb and Ta, and 0≦z≦0.2, 0≦x≦0.2, and 0≦y≦2 may be satisfied. In this basic composition formula, it is more preferable that 0.05≦z≦0.1 is satisfied. In this basic composition formula, it is more preferable that 0.05≦x≦0.1 is satisfied. In addition, in this basic composition formula, it is more preferable that 0.1≦y≦0.8 is satisfied. In such a range, the ion conductivity can be more suitable.

[0022] Alternatively, the solid electrolyte may be, for example, a common Li 3 N, Li called LISICON 14 Zn(GeO 4 ) 4 , Li sulfide 3.25 Ge 0.25 P 0.75 S 4 , perovskite-type La 0.5 Li 0.5 TiO 3 , (La 2 / 3 Li 3x □ 1 / 3-2x )TiO 3 (□: atomic vacancy), garnet-type Li 7 La 3 Zr 2 O 12 , LiTi called NASICON type 2 (PO 4 ) 3 , Li 1.3 M 0.3 Ti 1.7 (PO 3 ) 4 (M=Sc, Al) and the like. Also, glass ceramics 80Li 2 S·20P 2 S 5 Li obtained from glass with the composition (mol%) 7 P 3 S11 Furthermore, Li, a sulfide-based material with high electrical conductivity, 10 Ge 2 P.S. 2 Glass-based inorganic solid electrolytes include Li 2 S-SiS 2 , Li 2 S-SiS 2 - LiI, Li 2 S-SiS 2 -Li 3 PO 4 , Li 2 S-SiS 2 -Li 4 SiO 4 , Li 2 SP 2 S 5 , Li 3 PO 4 -Li 4 SiO 4 , Li 3 BO 4 -Li 4 SiO 4 , and SiO 2 , GeO 2 , B 2 O 3 , P 2 O 5 Li as a glass-based material 2 O is used as a network modifier. 2 S-GeS 2 system, Li 2 S-GeS 2 -ZnS, Li 2 S-Ga 2 S 2 system, Li 2 S-GeS 2 -Ga 2 S 3 system, Li 2 S-GeS 2 -P 2 S 5 system, Li 2 S-GeS 2 -SbS 5 system, Li 2 S-GeS 2 -Al 2 S 3system, Li 2 S-SiS 2 system, Li 2 SP 2 S 5 system, Li 2 S-Al 2 S 3 system, LiS-SiS 2 -Al 2 S 3 system, Li 2 S-SiS 2 -P 2 S 5 These solid electrolytes may be formed into a plate shape and disposed between the deposition electrode and the counter electrode.

[0023] The control unit is a controller that controls the entire device. The control unit may apply a current to the counter electrode and the deposition electrode at a current density per unit active material mass contained in the electrode material in the range of 8 mA / g or more and 380 mA / g or less. For example, the current density per unit active material mass is preferably 20 mA / g or more, more preferably 45 mA / g or more, and may be 50 mA / g or more. The current is preferably 300 mA / g or less, more preferably 200 mA / g or less, and even more preferably 90 mA / g or less. It is more preferable that the control unit applies a current at a current density per active material contained in the electrode material in the range of 45 mA / g or more and 90 mA / g or less. In this device, when the concentrations of cations and anions contained in the aqueous electrolyte are lower, it is preferable to apply the current at a lower rate.

[0024] Next, a specific example of a lithium metal manufacturing apparatus will be described with reference to the drawings. FIG. 1 is an explanatory diagram showing a schematic diagram of an example of a lithium metal manufacturing apparatus 10 of the present disclosure. As shown in FIG. 1, the lithium metal manufacturing apparatus 10 includes a deposition electrode 11, a nonaqueous electrolyte 12, an ion conductive medium 13, an electrode material 14, a counter electrode 15, an aqueous electrolyte 16, a storage unit 19, and a control unit 20. Note that each of the configurations may be any of those described above. The cathode compartment 21 includes the deposition electrode 11 and the nonaqueous electrolyte 12, and the anode compartment 22 includes the electrode material 14, the counter electrode 15, and the aqueous electrolyte 16, and each compartment is separated by the ion conductive medium 13. The electrode material 14, which is a lithium supply source, is adjacent to the counter electrode 15. In addition, the generated lithium metal is deposited on the surface of the deposition electrode 11. The ionically conductive medium 13 is a solid electrolyte that conducts lithium ions, and isolates the nonaqueous electrolyte solution 12 from the aqueous electrolyte solution 16 so as not to come into contact with each other. The top of the container 19 may be open to the atmosphere.

[0025] In the thus configured apparatus 10 for producing metallic lithium, a current is applied between the deposition electrode 11 and the counter electrode 15, thereby extracting lithium on the counter electrode 15 side and depositing metallic lithium on the deposition electrode 11. The current density during this current application may be appropriately set in consideration of the apparatus configuration, deposition efficiency, and the like, but is preferably in the range of 8 mA / g or more and 380 mA / g or less.

[0026] (Metal Lithium Manufacturing Method) In this manufacturing method, for example, metallic lithium may be manufactured using the metallic lithium manufacturing apparatus described above. This metallic lithium manufacturing apparatus includes a deposition electrode that contacts a non-aqueous electrolyte solution and deposits metallic lithium, a counter electrode that contacts an aqueous electrolyte solution and contains an electrode material containing lithium and faces the deposition electrode, and an ion conductive medium that is interposed between the deposition electrode and the counter electrode and conducts lithium ions while separating the non-aqueous electrolyte solution from the aqueous electrolyte solution. This metallic lithium manufacturing method includes a deposition step in which metallic lithium is deposited on the deposition electrode from the lithium on the counter electrode side by applying a current between the deposition electrode and the counter electrode.

[0027] In this deposition step, it is preferable that the counter electrode contains a positive electrode material of a lithium secondary battery as an electrode material. In addition, in this deposition step, it is preferable to apply a current with a current density per active material contained in the electrode material in the range of 8 mA / g or more and 380 mA / g or less. Furthermore, in the deposition step, it is more preferable to apply a current with a current density per active material contained in the electrode material in the range of 45 mA / g or more and 90 mA / g or less. This deposition step can be performed at room temperature, for example, 20°C or more and 30°C or less. The deposition step may also be performed at 30°C or more or 40°C or more.

[0028] In the deposition process, when lithium is extracted from the electrode material (e.g., the positive electrode) contained in the anode compartment, the cell voltage rises. When the worker confirms this voltage rise, he replaces the electrode material with a new one and continues producing metallic lithium. After repeating this electrode material replacement and the metallic lithium layer on the deposition electrode grows to the desired thickness, the worker recovers the deposition electrode in an atmosphere with a dew point of -38°C or lower, peels off the metallic lithium layer from the deposition electrode, and recovers metallic lithium.

[0029] The lithium metal manufacturing apparatus and method for manufacturing lithium metal described above can manufacture lithium metal more easily. The reason why such an effect is obtained is presumed to be as follows. For example, in this lithium metal manufacturing apparatus, the electrode material of a lithium secondary battery can be used as a supply source for the counter electrode. In addition, since an aqueous electrolyte is used for the counter electrode, it is easy to handle. Therefore, the lithium metal manufacturing apparatus and method for manufacturing lithium metal can obtain lithium metal more easily.

[0030] In the lithium metal manufacturing apparatus and lithium metal manufacturing method, an electrode material as a lithium supply source is disposed adjacent to a counter electrode in an anode compartment separated by an ion conductive medium. A non-aqueous electrolyte is accommodated in a cathode compartment separated by an ion conductive medium together with a deposition electrode. Then, by electrolysis in which an electric current is applied to the deposition electrode and the counter electrode, lithium ions are extracted from the lithium supply source, the ion conductive medium is diffused, and the lithium metal is deposited on the deposition electrode. In the present disclosure, lithium metal can be manufactured at room temperature, and lithium metal can be generated with only the energy of the charging voltage x capacity of the lithium secondary battery, so that a significant reduction in energy is possible. In addition, the present disclosure is a method for electrochemically extracting lithium ions mainly from the positive electrode of used lithium secondary batteries, which are expected to increase rapidly in the future, and can realize the generation of high-value-added lithium metal. This method allows a significant reduction in energy by generating lithium metal directly without going through lithium carbonate or the like. In addition, since it is possible to selectively extract only lithium ions from the electrode material as a lithium supply source, it is possible to reduce the contamination of lithium when recovering other valuable elements in a post-recycling process.

[0031] It goes without saying that the present disclosure is in no way limited to the above-described embodiment, and can be embodied in various forms as long as it falls within the technical scope of the present disclosure.

[0032] The present disclosure may be any one of the following [1] to

[10] . [1] An apparatus for producing metallic lithium, comprising: a deposition electrode on which metallic lithium is deposited in contact with a non-aqueous electrolyte; a counter electrode that is in contact with an aqueous electrolyte and contains a lithium-containing electrode material and faces the deposition electrode; an ion conductive medium interposed between the deposition electrode and the counter electrode, which separates the nonaqueous electrolyte solution from the aqueous electrolyte solution and conducts lithium ions; a control unit that applies a current between the deposition electrode and the counter electrode to deposit metallic lithium from the lithium on the counter electrode side onto the deposition electrode; A lithium metal manufacturing apparatus comprising: [2] The apparatus for producing metallic lithium according to [1], wherein the counter electrode contains a positive electrode material of a lithium secondary battery as the electrode material. [3] The apparatus for producing metallic lithium according to [1] or [2], wherein the control unit applies the current so that the current density per active material contained in the electrode material is in the range of 8 mA / g or more and 380 mA / g or less. [4] The apparatus for producing metallic lithium according to any one of [1] to [3], wherein the control unit applies the current so that the current density per active material contained in the electrode material is in the range of 45 mA / g or more and 90 mA / g or less. [5] The counter electrode is formed of at least one of stainless steel and aluminum, The apparatus for producing metallic lithium according to any one of [1] to [4], wherein the deposition electrode is formed of at least one of copper and nickel. [6] The apparatus for producing metallic lithium according to any one of [1] to [5], wherein the aqueous electrolyte of the counter electrode contains 0 mM or more, more preferably 0.01 mM or more and 10 M or less of cations and anions, and the nonaqueous electrolyte of the deposition electrode has a Li-containing salt dissolved therein at a concentration of 0.01 mM or more and 4 M or less. [7] A method for producing metallic lithium comprising: a deposition electrode in contact with a non-aqueous electrolyte solution and on which metallic lithium is deposited; a counter electrode in contact with an aqueous electrolyte solution and containing an electrode material containing lithium, the counter electrode facing the deposition electrode; and an ion conductive medium interposed between the deposition electrode and the counter electrode, separating the non-aqueous electrolyte solution from the aqueous electrolyte solution and conducting lithium ions, a deposition step of applying a current between the deposition electrode and the counter electrode to deposit metallic lithium from the lithium on the counter electrode; A method for producing metallic lithium comprising the steps of: [8] The method for producing metallic lithium according to [7], wherein the counter electrode contains a positive electrode material of a lithium secondary battery as the electrode material. [9] The method for producing metallic lithium according to [7] or [8], wherein in the precipitation step, the current is applied at a current density per active material contained in the electrode material in the range of 8 mA / g or more and 380 mA / g or less.

[10] The method for producing metallic lithium according to any one of [7] to [9], wherein in the precipitation step, the current is applied at a current density per active material contained in the electrode material in the range of 45 mA / g or more and 90 mA / g or less. EXAMPLES

[0033] Examples in which the manufacturing apparatus and method for metallic lithium disclosed in this specification were specifically examined will be described below as Experimental Examples, with Experimental Examples 1 to 14 corresponding to examples of the present disclosure.

[0034] (1)Method of producing metallic lithium A selective Li-ion conductor, solid electrolyte (Li 2 O-Al 2 O 3 -SiO 2 -P 2 O 5 -TiO 2 System, LICGC TM Metallic lithium was produced using a cell (Figure 1) with a separate anode and cathode compartment (AG-01; manufactured by Ohara Corporation). A 20 mm diameter SUS plate in contact with the positive electrode of the lithium secondary battery was used as the counter electrode (anode), and a 23 mm diameter Cu foil was used as the deposition electrode (cathode). Lithium was extracted from the positive electrode of the lithium ion battery by electrolysis, and metallic lithium was deposited on the Cu foil. LiFe(PO 4 ) (LFP), or LiNi 0.6 Co 0.2 Mn 0.2 O 2 The positive electrodes of lithium ion batteries were made of NCM622 as the active material. The active material, conductive material (HS-100), and binder (PVDF#7305) were mixed in a ratio of 92:5:3, and the weight of the active material was 7-8 mg / cm. 2 The structure was such that the aluminum current collector was coated on only one side.

[0035] Figure 2 shows the electrode material as a lithium supply source. Figure 2A shows the cut electrode, Figure 2B shows the broken electrode, and Figure 2C shows the black mass. The positive electrode of the lithium secondary battery is an electrode cut to a diameter of 19 mm, a 5.12 cm 2 The electrodes are placed 0.03 to 0.05 cm apart. 2 The anode compartment contained an aqueous electrolyte (6M-LiNO 3 The first electrolyte was lithium hexafluorophosphate (LiPF 6 ) was dissolved in a mixed solvent of ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC) in a volume ratio of 3:4:3 to form an electrolyte (1M-LiPF 6 / EC+DMC+EMC). Also, LiPF 6 The electrolyte (1M-LiPF 6 The second electrolyte was 1 M LiTFSI / EC+DEC. The third electrolyte was 1 M LiTFSI / DOL+DME, which was prepared by dissolving lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) in a mixed solvent of 1,3-dioxolane (DOL) and dimethoxyethane (DME) in a volume ratio of 1:1. The anode side was open to the atmosphere, and electrolysis was performed at a constant current with a current density per lithium ion positive electrode active material in the range of 5 to 732 mA / g.

[0036] (2) X-ray powder diffraction (XRD) measurement The XRD patterns of the lithium ion battery positive electrode and Cu foil after electrolysis were measured to examine the change in the active material phase of the anode and the presence or absence of Li metal generation at the cathode. The detection of metallic lithium in this XRD measurement confirmed the recovery of metallic lithium. XRD measurements were performed using an XRD device (Ultima IV manufactured by Rigaku Corporation) with CuKα X-rays at a voltage of 40 kV, a current of 40 mA, and a scan rate of 10 ° / min. The obtained XRD patterns were analyzed using XRD analysis software (JADE Pro).

[0037] [Experimental Examples 1-14] Experimental Example 1 was prepared by using an LFP electrode as the Li supply source, a first electrolyte as the non-aqueous electrolyte solution for the cathode, and a current density per unit active material mass of 5 mA / g. Experimental Example 2 was prepared by using a second electrolyte as the non-aqueous electrolyte solution for the cathode, and a current density per unit active material mass of 9 mA / g, except that the same experiment as Experimental Example 1 was performed. Experimental Example 3 was prepared by using a second electrolyte as the non-aqueous electrolyte solution for the cathode, and a current density per unit active material mass of 22 mA / g, except that the same experiment as Experimental Example 1 was performed. Experimental Example 4 was prepared by using a third electrolyte solution for the cathode, and a current density per unit active material mass of 22 mA / g, except that the same experiment as Experimental Example 1 was performed. Experimental Example 6 was prepared by using a second electrolyte solution for the cathode, and a current density per unit active material mass of 47 mA / g, except that the same experiment as Experimental Example 1 was performed. Experimental Example 7 was the same as Experimental Example 1 except that the non-aqueous electrolyte of the cathode was the second electrolyte and the current density per unit active material mass was 92 mA / g. Experimental Example 8 was the same as Experimental Example 1 except that the current density per unit active material mass was 90 mA / g. Experimental Example 9 was the same as Experimental Example 1 except that the current density per unit active material mass was 177 mA / g. Experimental Example 10 was the same as Experimental Example 1 except that the current density per unit active material mass was 376 mA / g. Experimental Example 11 was the same as Experimental Example 1 except that the current density per unit active material mass was 732 mA / g. Experimental Example 12 was the same as Experimental Example 1 except that the Li supply source was a cut LFP electrode and the current density per unit active material mass was 50 mA / g. Experimental Example 13 was the same as Experimental Example 1 except that the Li supply source was a black mass and the current density per unit active material mass was 87 mA / g. Experimental Example 2 was the same as Experimental Example 1 except that the nonaqueous electrolyte solution of the cathode was the second electrolyte solution and the current density per unit active material mass was 9 mA / g. Experimental Example 14 was the same as Experimental Example 1 except that the Li supply source was an NMC622 electrode, the nonaqueous electrolyte solution of the cathode was the second electrolyte solution and the current density per unit active material mass was 25 mA / g.

[0038] (3) Results and Discussion Under each condition of Experimental Examples 1 to 14, Fe(PO 4 Table 1 shows the ratio (mass%) of lithium in the electrolyte (A) and the presence or absence of Li deposition at the cathode. As shown in Experimental Examples 1 to 11, the generation of metallic lithium by electrolysis using an LFP electrode as the anode was examined. FIG. 3 is an explanatory diagram of the voltage change of the cells of Experimental Examples 1, 2, and 5 to 11 in which electrolysis was performed using an LFP electrode as a supply source at different current densities. In FIG. 3, the horizontal axis is the electric capacity per LFP active material. In electrolysis at a current density of 9 mA / g or less, the cell voltage remained plateau even when it exceeded 300 mAh / g, whereas in electrolysis at a current density of 22 mA / g or more, the cell voltage rose around the time when the capacity reached 170 mAh / g, which is the theoretical capacity value of LFP. This rise in cell voltage is expected to be due to a decrease in the Li concentration of the LFP active material. In the cells in which the cell voltage did not rise, electrolysis was stopped at 231 mAh / g in Experimental Example 1 with a current density of 5 mA / g, and at 353 mAh / g in Experimental Example 2 with a current density of 9 mA / g. FIG. 4 is a graph showing the relationship between the capacity change of the electrolysis reaction in the LFP electrode cell and the current density. FIG. 5 is a graph showing the relationship between the plateau voltage change of the LFP electrode cell and the current density. As shown in FIG. 4, there was a tendency for the electrolysis capacity to increase as the current density decreased. There was also a tendency for the cell voltage to increase with increasing current density, but this change was not linear, and as shown in FIG. 5, there was a stepwise increase in current density at 5, 9 to 92, 177 to 376, and 732 mA / g. In the LFP electrode in the anode compartment, the LFP phase was Fe(PO 4 ) phase, resulting in LiFe(PO 4 ) →Fe(PO 4 )+Li + +e - ) is predicted to occur.

[0039] Figure 6 shows the XRD patterns of the LFP electrode before and after electrolysis in Experimental Example 7. As shown in Figure 6, the active material, which was a single LFP phase before electrolysis, underwent a Li removal reaction due to electrolysis, and after electrolysis, it became Fe(PO 4 It was confirmed that the LFP electrode changed to a single phase of Fe(PO 4) phase of the LFP electrode active material versus current density. 4 In Experimental Example 1, in which a current density of 5 mA / g was applied, the Fe(PO 4 The ratio of the Fe(PO 4 The ratio of the Fe(PO ) phase was 50-60 mass%, and approximately 90 mass% at a current density of 47 mA / g or more. From the above, it was shown that a current density of 9 mA / g or more is necessary for the Li removal reaction at the LFP electrode, and a current density of 47 mA / g or more is desirable for efficient Li removal reaction. As shown in Experimental Example 3, even in electrolysis at a current density of 9 mA / g, when the capacity was increased to 625 mAh / g, the Fe(PO 4 It was found that the ratio of the .alpha.-phase increased to 89.2 mass%. In other words, it was found that the deposition of metallic lithium progresses depending on the applied current density itself as well as the capacity range. On the other hand, a stepwise increase in cell voltage has been observed as the current density increases. Considering energy efficiency, a low cell voltage is desirable. For example, this current density is desirably 376 mA / g or less, and when even greater energy efficiency is desired, 90 mA / g or less is desirable.

[0040] On the other hand, Li metal is expected to be precipitated on the Cu foil, which is the cathode, by electrolysis. Figure 8 is a photograph of the precipitate on the Cu foil after electrolysis in Experimental Example 5. Figure 9 is an XRD pattern of the Cu foil after electrolysis in Experimental Example 5. As shown in Figure 8, a gray substance was deposited in the area (diameter 17 mm) that was in contact with the non-aqueous electrolyte. As shown in Figure 9, the 110 diffraction peak of metallic lithium was detected in the XRD pattern of the Cu foil on which this gray deposit was formed, confirming that metallic lithium was precipitated on the Cu foil.

[0041] Next, the production of metallic lithium by electrolysis using cut LFP electrodes and black mass as the anode was examined (Experimental Examples 8, 12, and 13). In Experimental Example 12, the cut LFP electrodes shown in FIG. 2B were randomly placed in the anode compartment and pressed down from above with a SUS plate, and electrolysis was performed at a current density of 50 mA / g. In Experimental Example 12, the XRD pattern of the cut LFP electrodes after electrolysis showed that the active material was Fe(PO 4 ) single phase, confirming that the Li depletion reaction occurred smoothly. In Experimental Example 12, Li deposition on the Cu foil of the cathode was also confirmed. In Experimental Example 13, the black mass shown in FIG. 2C was placed in the anode compartment and pressed down from above with a SUS plate, and electrolysis was performed at a current density of 87 mA / g. After electrolysis, 84.2% of the active material in the black mass was Fe(PO 4 ) phase, confirming that a Li depletion reaction had occurred. In addition, in Experimental Example 13, Li deposition on the Cu foil cathode was also confirmed.

[0042] Next, the production of metallic lithium by electrolysis using an NCM622 electrode as the anode was examined (Example 14). Electrolysis was performed using an NCM622 electrode with a diameter of 19 mm as the anode and a current density of 25 mA / g until the cell voltage reached 4.4 V. Figure 10 shows the voltage change during electrolysis of the cell in Example 14. Figure 11 shows the XRD patterns of the NCM622 electrode before and after electrolysis in Example 14. Figure 12 shows the XRD pattern of the Cu foil after electrolysis in Example 14. As shown in Figure 10, it is known that the lattice constants a and c of the NCM active material change depending on the Li composition (J. Am. Chem. Soc. 2019, 141, 5097-5101, Adv. Energy Mater. 2018, 8, 1701788). The lattice constants a and c calculated from the XRD pattern were 2.8706 Å and 14.216 Å before electrolysis, but changed to 2.8147 Å and 14.389 Å after electrolysis. From these lattice constants, the composition of the NCM active material after electrolysis was approximately Li 0.3 (Ni 0.6 Co 0.2 Mn 0.2 )O 2(Adv. Energy Mater. 2018, 8, 1701788) In addition, deposition of metallic lithium was confirmed on the Cu foil, which was the deposition electrode.

[0043] The above experimental results show that the lithium metal production method and production device disclosed herein can produce lithium metal using LFP and NCM, which are electrode materials for lithium secondary batteries, as a Li supply source. It was also found that lithium metal can be produced using electrode materials in various states as they are.

[0044] [Table 1]

[0045] [Experimental Examples 15-33] Next, the concentration and type of the aqueous solution contained in the anode compartment were examined. Using the same device as in Experimental Example 1, lithium was extracted from the positive electrode of the lithium ion battery by electrolysis, and lithium metal was deposited on Cu foil. The above-mentioned LiFe(PO 4 The positive electrode of a lithium ion battery using limonene-based polymer (LFP) as the active material was used. This LFP electrode was cut to a diameter of 19 mm to prepare an electrode. The anode compartment contained 0.01 mM to 6 M LiNO 3 The cathode compartment is filled with a non-aqueous electrolyte, LiPF 6 The electrolyte (1M-LiPF 6 The anode side was open to the atmosphere, and electrolysis was carried out at a constant current of either 23mAh / g, 46mAh / g, or 91mAh / g per lithium ion positive electrode active material.

[0046] [Experimental Examples 34-38] In the anode compartment, 0.5 mM to 2 M Li 2 (SO 4Experimental Examples 34 to 38 were conducted under the same conditions as in Experimental Example 15, except that an aqueous solution of 23 mAh / g or 91 mAh / g was injected and the current density per lithium ion positive electrode active material was a constant current.

[0047] [Experimental Examples 39-41] Experimental Examples 39 to 41 were conducted under the same conditions as Experimental Example 15, except that an aqueous LiOH solution of 0.01 mM to 10 mM was injected into the anode compartment and the current density per lithium ion positive electrode active material was a constant current of 91 mAh / g.

[0048] [Experimental Examples 42-43] We investigated whether it was possible to generate lithium metal by using pure water instead of the Li salt aqueous solution in the anode compartment. Because the Li salt from the electrolyte adheres to the used LFP electrodes to be recycled, two types of LFP electrodes were used as the lithium supply source: one with Li salt attached and one without. The LFP electrodes with Li salt attached were prepared by placing an LFP electrode with a diameter of 19 mm in an electrolyte (1M-LiPF 6 The electrodes were immersed in a 1000-kV lithium ion battery (1000V / EC+DEC) for 1 hour, then vacuumed and dried. The Li salt-attached electrodes were electrolyzed at a current density of 46 mAh / g, and the electrodes without Li salt were electrolyzed at a current density of 23 mAh / g to produce lithium metal.

[0049] Inductively Coupled Plasma (ICP) Analysis After electrolysis, the current collector was peeled off from the LFP electrode, and the Li content was quantitatively analyzed by inductively coupled plasma optical emission spectroscopy (ICP-OES, PS3520UVDDII II, Hitachi High-Tech Science).

[0050] X-ray powder diffraction (XRD) measurements The XRD patterns of the LFP electrode and Cu foil after electrolysis were measured to examine the change in the active material phase of the electrode and the presence or absence of Li metal generation at the cathode. The detection of Li metal in this XRD measurement confirmed the recovery of lithium metal. XRD measurements were performed using an XRD device (Ultima IV manufactured by Rigaku Corporation) with CuKα X-rays at a voltage of 40 kV, a current of 40 mA, and a scan rate of 10 ° / min. The obtained XRD patterns were analyzed using XRD analysis software (JADE Pro).

[0051] (Results and Discussion) In Experimental Examples 15 to 43, the type and concentration of the aqueous solution in the anode compartment, the current density per LFP active material (mA / g), the electrolysis capacity per LFP active material (mAh / g), and the FePO per LFP active material of the LFP electrode after electrolysis 4 The ratio (mass%) of Fe(PO 4 The ratio of Fe(PO 4 ) phase, resulting in LiFe(PO 4 ) →Fe(PO 4 )+Li + +e - ) is expected to occur. Figure 13 shows the XRD patterns of the LFP electrode of Example 33 before and after electrolysis. Figure 14 shows a photograph of the deposit on the Cu foil after electrolysis of Example 33. Figure 15 shows the XRD pattern of the Cu foil after electrolysis of Example 33. The active material was a single LFP phase before electrolysis, but a delithiation reaction occurred due to electrolysis, and after electrolysis, Fe(PO 4) single phase. On the other hand, Li metal is expected to precipitate on the Cu foil, which is the cathode, by electrolysis. As shown in Figure 14, a gray substance was deposited in the area (diameter 17 mm) that was in contact with the non-aqueous electrolyte. As shown in Figure 15, the XRD pattern of the Cu foil on which this gray deposit was formed showed the 110 diffraction peak of lithium metal, confirming that lithium metal had precipitated on the Cu foil. In addition, as shown in Table 2, Li precipitation was confirmed in aqueous solutions containing various lithium salts, such as lithium nitrate aqueous solution, lithium sulfate aqueous solution, and lithium hydroxide aqueous solution, at low to high concentrations and low to high rates.

[0052] Regarding lithium metal generation in a cell using pure water, the LFP electrode was placed in a Li-containing electrolyte (1M-LiPF 6 The weight of the LFP electrode after immersion in the Li-containing electrolyte increased by 3.8 mg compared to before immersion. The only component of the electrolyte that remained after vacuum drying was LiPF 6 Therefore, when this Li salt-attached electrode is placed in 2 mL of pure water in the cathode compartment, the attached LiPF 6 When all the Li ions are dissolved, the Li concentration is calculated to be approximately 5 mM. The delithiation ratio of the electrodes after electrolysis by ICP analysis was 84.5 mass% in Experimental Example 42 and 91 mass% in Experimental Example 43. This shows that the delithiation reaction occurs in LFP even when the aqueous solution in the anode compartment is pure water, and lithium can be recovered.

[0053] [Table 2]

[0054] It goes without saying that the present disclosure is in no way limited to the above-described embodiments, and can be embodied in various forms as long as they fall within the technical scope of the present disclosure. [Industrial Applicability]

[0055] The metallic lithium production apparatus and the metallic lithium production method disclosed in this specification can be used in technical fields of regenerating and producing metallic lithium. [Explanation of symbols]

[0056] 10 Metallic lithium production apparatus, 11 Deposition electrode, 12 Non-aqueous electrolyte, 13 Ion conductive medium, 14 Electrode material, 15 Counter electrode, 16 Aqueous electrolyte, 19 Storage section, 20 Control section, 21 Cathode compartment, 22 Anode compartment.

Claims

1. An apparatus for producing metallic lithium, comprising: a deposition electrode on which metallic lithium is deposited in contact with a non-aqueous electrolyte; a counter electrode that is in contact with an aqueous electrolyte and contains a lithium-containing electrode material and faces the deposition electrode; an ion conductive medium interposed between the deposition electrode and the counter electrode, which separates the nonaqueous electrolyte solution from the aqueous electrolyte solution and conducts lithium ions; a control unit that applies a current between the deposition electrode and the counter electrode to deposit metallic lithium from the lithium on the counter electrode side onto the deposition electrode; A metallic lithium manufacturing apparatus comprising:

2. 2. The apparatus for producing metallic lithium according to claim 1, wherein the counter electrode contains a positive electrode material of a lithium secondary battery as the electrode material.

3. 3. The apparatus for producing metallic lithium according to claim 1, wherein the control unit applies the current so that a current density per active material contained in the electrode material is in the range of 8 mA / g or more and 380 mA / g or less.

4. 3. The apparatus for producing metallic lithium according to claim 1, wherein the control unit applies the current so that a current density per active material contained in the electrode material is in the range of 45 mA / g or more and 90 mA / g or less.

5. The counter electrode is formed of at least one of stainless steel and aluminum, 3. The apparatus for producing metallic lithium according to claim 1, wherein the deposition electrode is made of at least one of copper and nickel.

6. The aqueous electrolyte of the counter electrode contains cations and anions at 0 mM or more and 10 M or less, 3. The apparatus for producing metallic lithium according to claim 1, wherein the nonaqueous electrolyte of the deposition electrode contains a Li-containing salt dissolved therein at a concentration of 0.01 mM or more and 4 M or less.

7. A method for producing metallic lithium comprising: a deposition electrode in contact with a non-aqueous electrolyte solution and on which metallic lithium is deposited; a counter electrode in contact with an aqueous electrolyte solution and containing an electrode material containing lithium, the counter electrode facing the deposition electrode; and an ion conductive medium interposed between the deposition electrode and the counter electrode, separating the non-aqueous electrolyte solution from the aqueous electrolyte solution and conducting lithium ions, a deposition step of applying a current between the deposition electrode and the counter electrode to deposit metallic lithium from the lithium on the counter electrode; A method for producing metallic lithium comprising the steps of:

8. The method for producing metallic lithium according to claim 7 , wherein the counter electrode contains a positive electrode material of a lithium secondary battery as the electrode material.

9. 9. The method for producing metallic lithium according to claim 7 or 8, wherein in the precipitation step, the current is applied at a current density per active material contained in the electrode material in the range of 8 mA / g or more and 380 mA / g or less.

10. 9. The method for producing metallic lithium according to claim 7 or 8, wherein in the deposition step, the current is applied at a current density per active material contained in the electrode material in the range of 45 mA / g or more and 90 mA / g or less.

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