Lithium recovery device, multi-chamber lithium recovery device, and lithium recovery method

Abstract

In a lithium recovery device (1), a treatment tank (7) is divided into three chambers by an ion-conducting membrane (31) and a lithium-ion-conducting electrolyte membrane (2) in the order of chambers (11, 12, 13), a power source (5) is connected between electrodes (41, 42) provided in each of the chambers (11, 13) at both ends with the first electrode chamber (11) side as the positive side, water (S1) is accommodated in the first electrode chamber (11), a non-aqueous Li solution (FS) is accommodated in the Li supply chamber (12), and the lithium ion-conducting electrolyte membrane (2) is arranged in the Li supply chamber (12). An aqueous solution (RS) for Li recovery is accommodated in the Li recovery chamber (13). When a voltage is applied by a power source (5), H + moves from water (S1) through the ion-conducting membrane (31) to the Li-containing non-aqueous solution (FS), and in the Li-containing non-aqueous solution (FS) to which H + is supplied, Li + moves into the lithium-ion-conducting electrolyte membrane (2) and Li + in the lithium-ion-conducting electrolyte membrane (2) moves into the aqueous solution (RS) for Li recovery in order to maintain charge balance.

Description

Technical Field

[0001] This invention relates to a lithium recovery apparatus and a lithium recovery method for selectively recovering lithium ions from non-aqueous solutions. Background Technology

[0002] Lithium (Li) is a high-demand resource, used as fuel in lithium-ion batteries and nuclear fusion reactors, requiring stable and inexpensive extraction methods. As a stable source of Li, Li-ion batteries with cationic Li-ion are a key resource. + The form of dissolved seawater, etc. Furthermore, since lithium-ion secondary batteries mainly contain Li in the form of lithium cobalt oxide (LiCoO2) at the positive electrode, an inexpensive recycling technology for recovering Li from batteries discarded due to battery life, etc., is desired. Adsorption methods have been used for recovering Li from seawater, etc., but as a more selective method, a recovery method using electrodialysis is being developed. This method uses an electrolyte membrane with lithium-ion conductivity (e.g., Patent Documents 1-3, Non-Patent Document 1).

[0003] Reference Figure 25 This describes an example of a Li recovery method using electrodialysis as described in Patent Document 1, etc. The lithium recovery apparatus 101 is configured such that a processing tank 107 is divided into a Li supply chamber 112 and a Li recovery chamber 113 by a lithium-ion conductive electrolyte membrane (hereinafter, electrolyte membrane) 2. A power supply 105 is connected between an electrode 141 in the Li supply chamber 112 and an electrode 142 in the Li recovery chamber 113, with the electrode 141 as the positive terminal. A Li-containing aqueous solution SW, such as seawater, is added to the Li supply chamber 112 as a Li source, and an aqueous solution RS, such as pure water, is added to the Li recovery chamber 113. Lithium ions (Li₂O₃) are dissolved in the Li-containing aqueous solution SW. + ) and other metal ions (M n+ ), hydrogen ions (H) + ) and hydroxide ions (OH) - ) and other anions, such as chloride ions (Cl ions) - ), sulfate ions (SO4) 2- )wait.

[0004] When a voltage is applied through power supply 105, oxygen (O2) is generated near electrode 141 in the Li-containing aqueous solution SW of Li supply chamber 112, as shown in equation (1), and an oxygen (O2) is generated on the surface of electrolyte membrane 2, as shown in equation (2). Furthermore, the Li-containing aqueous solution SW contains Cl... -In this case, chlorine gas (Cl2) is further generated near electrode 141. On the other hand, in the Li recovery aqueous solution RS of Li recovery chamber 113, the reaction of formula (3) occurs on the surface (back side) of electrolyte membrane 2, and the reaction of formula (4) occurs near electrode 142 to generate hydrogen gas (H2). Furthermore, in each formula, the lithium ions (Li) contained in electrolyte membrane 2 are... + ) is represented as Li + (electrolyte), other ions (Li) + H + OH - ) represents ions dissolved in aqueous solution. The following formula (2) represents Li in solution. + The reaction that moves into electrolyte membrane 2 is represented by the following equation (3): Li in electrolyte membrane 2 + The reaction involves the movement of Li into the solution. As a result, the Li contained in the Li-containing aqueous solution SW, electrolyte membrane 2, and Li recovery aqueous solution RS are utilized. + The electrochemical potential difference makes Li + The Li-containing aqueous solution SW permeates through electrolyte membrane 2 to the Li recovery aqueous solution RS. Because the lattice defect sites of electrolyte membrane 2 are small, they do not cause the Li-containing aqueous solution to migrate. + Large Na + Ca 2+ Metal ions M n+ Through. Therefore, Li + Li selectively migrates from the Li-containing aqueous solution SW to the Li recovery aqueous solution RS, enabling the extraction of Li in the Li recovery chamber 113. + An aqueous solution of lithium hydroxide (lithium hydroxide aqueous solution).

[0005] [Chemical Formula 1]

[0006] [Existing Technical Documents] [Patent Literature]

[0007] Patent Document 1: Japanese Patent Publication No. 6233877 Patent Document 2: Japanese Patent Publication No. 2019-141807 Patent Document 3: International Publication No. 2022 / 239864 [Non-patent literature]

[0008] Non-patent document 1: Kunugi S., Inaguma Y., Itoh M., "Electrochemical recovery and isotope separation of lithium ion employing lithium ion conductiveperovskite-type oxides", Solid State Ionics, Vol. 122, Issues 1-4, pp. 35-39, July 1999 Summary of the Invention

[0009] [The technical problem the invention aims to solve]

[0010] In the Li recovery method using electrodialysis, in order to release electrons e at the anode as in the reaction of equation (1), - Using aqueous solutions containing dissolved seawater and acids from spent batteries as the Li supply source, hydroxide ions (OH-) are generated as anions through decomposition. - On the other hand, the Li-containing waste liquid generated during the manufacturing process of lithium-ion secondary batteries is mainly composed of electrolyte and is a non-aqueous solution containing Li salts such as LiPF6 dissolved in organic solvents such as ethylene carbonate (EC). When it is desired to recover Li from this waste liquid using electrodialysis, the organic solvent used as the solvent decomposes, thus preventing the organic solvent from being recovered for reuse. Furthermore, high voltage is required to decompose the organic solvent, leading to large-scale equipment requirements. Additionally, as mentioned above, to recover Li from waste batteries, the waste batteries are crushed and dissolved in strong acids such as sulfuric acid (H2SO4). However, when the Li supply source is a low-pH aqueous solution, electrodialysis (Li recovery) proceeds slowly. Furthermore, when sodium hydroxide (NaOH) is added to obtain a high pH value, neutralization is required before discharging the highly alkaline aqueous solution after Li extraction, thus increasing costs. Moreover, before dissolving the waste batteries in acid, a calcination process is required to remove the organic solvent from the electrolyte.

[0011] The present invention was made in view of the aforementioned problems, and its technical problem is to provide a lithium recovery method and lithium recovery apparatus that can recover lithium from a non-aqueous solution containing lithium dissolved in an organic solvent using electrodialysis in a state in which the organic solvent can be recovered.

[0012] [Technical solutions used to solve technical problems]

[0013] That is, the lithium recovery device according to the present invention includes a processing tank, a lithium-ion conductive electrolyte membrane, a first ion-conducting membrane, a first electrode, a second electrode, and a power supply. The processing tank is divided into a first chamber, a second chamber, and a third chamber in that order. The lithium-ion conductive electrolyte membrane divides the processing tank into the first chamber and the second chamber. The first ion-conducting membrane divides the processing tank into the second chamber and the third chamber. The first electrode is disposed in the third chamber. The second electrode is disposed in a chamber at the end of the processing tank opposite to the third chamber. The positive terminal of the power supply is connected to the first electrode, and the negative terminal is connected to the second electrode, causing lithium ions to move from a non-aqueous solution containing lithium ions contained in the second chamber to water or an organic solvent contained in the first chamber. In the lithium recovery device, the first ion-conducting membrane conducts at least one cation other than lithium ions, or at least one water-soluble anion contained in the non-aqueous solution. Water is contained in the third chamber.

[0014] Another lithium recovery device according to the present invention includes a processing tank, a lithium-ion conductive electrolyte membrane, a second ion-conducting membrane, a first electrode, a second electrode, and a power supply. The processing tank is divided into a second chamber, a first chamber, and a third chamber in that order. The lithium-ion conductive electrolyte membrane divides the processing tank into the first chamber and the second chamber. The second ion-conducting membrane divides the processing tank into the first chamber and the third chamber, and does not conduct lithium ions. The first electrode is disposed in the second chamber. The second electrode is disposed in the third chamber. The positive terminal of the power supply is connected to the first electrode, and the negative terminal is connected to the second electrode, causing lithium ions to move from a non-aqueous solution containing lithium ions contained in the second chamber to water or an organic solvent contained in the first chamber. In the lithium recovery device, water is contained in the third chamber, and further water is contained in the second chamber.

[0015] The multi-chamber lithium recovery device of the present invention includes a lithium-ion conductive electrolyte membrane, a first ion-conducting membrane, a second ion-conducting membrane, a processing tank, a first electrode, a second electrode, and a power supply. The lithium-ion conductive electrolyte membrane comprises two or more membranes. The first ion-conducting membrane is disposed at one end of the first disposed lithium-ion conductive electrolyte membrane. The second ion-conducting membrane is disposed between the lithium-ion conductive electrolyte membranes and does not conduct lithium ions. The processing tank is formed by the first ion-conducting membrane and the lithium-ion conductive membrane. The conductive electrolyte membrane and the second ion-conducting membrane are divided into 5 or more chambers; the first electrode is disposed in one chamber at one end of the processing tank; the second electrode is disposed in the other chamber; the positive terminal of the power supply is connected to the first electrode, and the negative terminal is connected to the second electrode; water is contained in the chamber at one end of the processing tank, so that lithium ions move from the non-aqueous solution containing lithium ions contained in the two adjacent chambers separated by the lithium ion conductive electrolyte membrane at one end to the water contained at the other end.

[0016] The lithium recovery method of the present invention involves moving lithium ions contained in a non-aqueous solution in the second chamber to water or an organic solvent contained in the first chamber in a processing tank divided into a first chamber and a second chamber by a lithium-ion conductive electrolyte membrane. The processing tank is further divided into the second chamber and a third chamber by a first ion-conducting membrane that conducts at least one cation other than lithium ions, or at least one anion that is water-soluble and contained in the non-aqueous solution. Water is contained in the third chamber. A voltage is applied between a first electrode disposed in the third chamber and a second electrode disposed in a chamber at the end of the processing tank opposite to the third chamber, with the first electrode being positive.

[0017] Another lithium recovery method involved in this invention is a method in which lithium ions contained in a non-aqueous solution contained in the second chamber are moved to water or an organic solvent contained in the first chamber in a processing tank divided into a first chamber and a second chamber by a lithium-ion conductive electrolyte membrane, wherein water is further contained in the second chamber, and a voltage is applied between a first electrode disposed in the second chamber and a second electrode disposed in a chamber at the end of the processing tank that is separated from the second chamber, by a power source connected with the first electrode as positive.

[0018] Another lithium recovery method according to the present invention involves moving lithium ions from a non-aqueous solution containing lithium ions contained in one of two adjacent chambers separated by the lithium-ion conductive electrolyte membranes to water contained in the other chamber in a processing tank divided into five or more chambers by alternating arrangement of ion-conducting membranes and lithium-ion conductive electrolyte membranes from one end. The ion-conducting membranes disposed between the lithium-ion conductive electrolyte membranes do not conduct lithium ions. Water is contained in the chamber at one end of the processing tank. A voltage is applied between a first electrode in the chamber at one end of the processing tank and a second electrode in the chamber at the other end, with the first electrode connected positively, causing lithium ions to move from the non-aqueous solution containing lithium ions contained in the adjacent two chambers at one end to water contained in the other end.

[0019] [Invention Effects]

[0020] According to the lithium recovery apparatus and lithium recovery method of the present invention, an organic solvent containing dissolved Li salt can be used as the Li supply source. Attached Figure Description

[0021] Figure 1 This is a schematic diagram illustrating the structure of the lithium recovery apparatus according to the first embodiment of the present invention.

[0022] Figure 2 This describes the lithium recovery method according to the first embodiment of the present invention. Figure 1 A schematic diagram of a lithium recovery device is shown.

[0023] Figure 3 This is a schematic diagram illustrating the structure of a lithium recovery apparatus and a lithium recovery method according to a modified example of the first embodiment of the present invention.

[0024] Figure 4 This is a schematic diagram illustrating the structure of a lithium recovery apparatus and a lithium recovery method according to a modified example of the first embodiment of the present invention.

[0025] Figure 5 This is a schematic diagram illustrating the structure of the lithium recovery device according to the second embodiment of the present invention.

[0026] Figure 6 This describes the lithium recovery method according to the second embodiment of the present invention. Figure 5 A schematic diagram of a lithium recovery device is shown.

[0027] Figure 7 This is a schematic diagram illustrating the structure of the lithium recovery device according to the third embodiment of the present invention.

[0028] Figure 8This describes the lithium recovery method according to the third embodiment of the present invention. Figure 7 A schematic diagram of a lithium recovery device is shown.

[0029] Figure 9 This is a schematic diagram illustrating the structure of the lithium recovery apparatus and the lithium recovery method according to a variation of the third embodiment of the present invention.

[0030] Figure 10 This is a schematic diagram illustrating the structure of the lithium recovery device according to the fourth embodiment of the present invention.

[0031] Figure 11 This describes the lithium recovery method according to the fourth embodiment of the present invention. Figure 10 A schematic diagram of a lithium recovery device is shown.

[0032] Figure 12 This is a schematic diagram illustrating the structure of the lithium recovery apparatus according to the fifth embodiment of the present invention.

[0033] Figure 13 This describes the lithium recovery method according to the fifth embodiment of the present invention. Figure 12 A schematic diagram of a lithium recovery device is shown.

[0034] Figure 14 This is a schematic diagram illustrating the structure of the lithium recovery apparatus and the lithium recovery method according to a modified example of the fifth embodiment of the present invention.

[0035] Figure 15 This is a schematic diagram illustrating the structure of the lithium recovery apparatus according to the sixth embodiment of the present invention.

[0036] Figure 16 This describes the lithium recovery method according to the sixth embodiment of the present invention. Figure 15 A schematic diagram of a lithium recovery device is shown.

[0037] Figure 17 This is a schematic diagram illustrating the structure of the lithium recovery apparatus and the lithium recovery method according to a modified example of the sixth embodiment of the present invention.

[0038] Figure 18 This is a schematic diagram illustrating the structure of a multi-chamber lithium recovery device according to an embodiment of the present invention.

[0039] Figure 19 This describes the lithium recovery method involved in the embodiments of the present invention. Figure 18 A schematic diagram of a multi-chamber lithium recovery unit is shown.

[0040] Figure 20 This is a schematic diagram illustrating the structure of a multi-chamber lithium recovery device and a lithium recovery method according to a modified embodiment of the present invention.

[0041] Figure 21 This is a schematic diagram illustrating the structure of a multi-chamber lithium recovery device and a lithium recovery method according to a modified embodiment of the present invention.

[0042] Figure 22 This is a schematic diagram illustrating the structure of a multi-chamber lithium recovery device and a lithium recovery method according to a modified embodiment of the present invention.

[0043] Figure 23 This is a graph showing the shift in the amount of lithium recovered per unit time in the embodiments and comparative examples of the lithium recovery device involved in the present invention.

[0044] Figure 24 This is a graph showing the shift in the amount of lithium recovered per unit time in an embodiment of the lithium recovery device involved in the present invention.

[0045] Figure 25 This is a schematic diagram of a lithium recovery apparatus illustrating an example of a lithium recovery method from an aqueous solution using electrodialysis. Detailed Implementation

[0046] The lithium recovery apparatus and the manner in which the lithium recovery method is implemented according to the present invention will be described with reference to the accompanying drawings. In the drawings, for clarity, the size of certain elements is sometimes exaggerated, or the shape is sometimes simplified. Furthermore, in the description of each embodiment, the same reference numerals are used for elements identical to those in the preceding embodiments, and descriptions are appropriately omitted.

[0047] [First Embodiment] (Lithium recovery device) like Figure 1As shown, the lithium recovery apparatus 1 according to the first embodiment of the present invention includes: an electrolyte membrane (lithium-ion conductive electrolyte membrane) 2; an ion exchange membrane (first ion conductive membrane) 31; a processing tank 7, which is divided into three chambers by the ion exchange membrane 31 and the electrolyte membrane 2 in the order of chambers 11, 12, and 13; a first electrode 41, which is disposed in the chamber (third chamber) 11 at one end of the processing tank 7; a second electrode 42, which is disposed in the chamber (first chamber) 13 at the other end; and a power supply 5, which is connected between the electrodes 41 and 42 with the first electrode 41 as the positive electrode. The chamber (third chamber) 11 at one end, which is separated by the ion exchange membrane 31, is the first electrode chamber and is used to contain an aqueous solution (water) S1. The central chamber (second chamber) 12 is the Li supply chamber and is used to contain a non-aqueous solution containing Li FS. The chamber (first chamber) 13 at one end, which is separated by the electrolyte membrane 2, is the Li recovery chamber and is used to contain an aqueous solution RS for Li recovery. The lithium recovery device 1 may also include, as needed, a water supply device 81 for supplying water (aqueous solution S1) to the first electrode chamber 11 and circulation devices 82 and 83 respectively disposed in chambers 12 and 13. The lithium recovery device 1 allows lithium ions (Li...) to... + The solution moves from the non-aqueous Li-containing solution FS contained in the Li supply chamber 12 to the aqueous Li recovery solution RS contained in the Li recovery chamber 13.

[0048] Li-containing non-aqueous solutions (FS) are Li sources, meaning they contain lithium ions (Li) in an organic solvent. + ) and other metal ions M n+ and the anion A, which acts as a counterion to these. n- Non-aqueous solutions. Examples of such non-aqueous solutions include waste liquid generated during the manufacturing process of lithium-ion secondary batteries, and solutions obtained by crushing and dissolving used lithium-ion secondary batteries (waste batteries) in organic solvents. Unlike the case of dissolving in acid to recover metals such as Li, waste batteries may not be roasted. If the Li-containing non-aqueous solution FS is the aforementioned waste liquid, it is mainly composed of the usual liquid electrolyte used in lithium-ion secondary batteries, and may contain Li. + Other metal ions M n+ Sometimes, it also contains organic solvents used for cleaning. Liquid electrolytes are non-aqueous solutions made by dissolving Li salts such as LiPF6, LiClO4, LiBF4, LiN(CF3SO2)2, and LiN(C2F5SO2)2 in organic solvents such as ethylene carbonate (EC), propylene carbonate (PC), γ-butyrolactone, dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (EMC), 1,2-dimethoxyethane (DME), and acetonitrile. Additionally, the organic solvents used for cleaning and dissolving waste batteries are the same as those used for liquid electrolytes, such as EC, PC, or N-methyl-2-pyrrolidone (NMP). In this non-aqueous solution, the Li salts are dissolved in organic solvents such as ethylene carbonate (EC), propylene carbonate (PC), γ-butyrolactone, dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (EMC), 1,2-dimethoxyethane (DME), and acetonitrile. +It exists in the form of its counterions. Li + Counterions include hexafluorophosphate (PF6) ions. - ), tetrafluoroborate ion (BF4) - ), bis(fluorosulfonyl)imine ion ((FSO2)2N - FSA - ), trifluoromethanesulfonylimide ion ((CF3SO2)2N - TFSA - ), perchlorate ions (ClO4) - ), etc. If the non-aqueous solution containing Li (FS) is the solution for waste batteries, then Li... + Other metal ions M n+ It is Co 2+ Fe 2+ Cu 2+ Al 3+ Ni 2+ etc., with Li + Similarly, the anion is present as a counterion.

[0049] The Li recovery aqueous solution RS is used to contain Li recovered from the Li-containing non-aqueous solution FS. + The solution. To selectively obtain only Li from the metal, the aqueous solution RS for Li recovery is preferably free of Li. + Other metal ions (Na) + An aqueous solution of (etc.), more preferably free of OH-. - An aqueous solution containing non-halogen anions, especially halide ions, is used at the start of operation of lithium recovery unit 1, for example, as pure water. Alternatively, to allow Li to react immediately after operation begins... + The movement proceeds smoothly. At the start of operation of the lithium recovery unit 1, the preferred aqueous solution RS for Li recovery contains Li. + An aqueous solution of lithium hydroxide (LiOH) (LiOH aqueous solution).

[0050] Aqueous solution S1 supplies cations, such as hydrogen ions (H+) to non-aqueous solutions containing Li, FS. + The supply source for H is the aqueous solution S1, which is, for example, pure water at the start of operation of the lithium recovery unit 1. Alternatively, it can be used to supply H... + The movement to the Li-containing non-aqueous solution FS proceeds smoothly. The aqueous solution S1 can be an acidic, neutral, or alkaline aqueous solution (electrolyte aqueous solution) with a certain degree of high electronic conductivity. Moreover, the aqueous solution S1 preferably does not have a low pH value relative to the Li recovery aqueous solution RS after the start of operation (S1 < RS), and more preferably has a higher pH value relative to the Li recovery aqueous solution RS. Therefore, it is preferable to make it an alkaline aqueous solution.

[0051] The electrolyte membrane 2 is an electrolyte with lithium-ion conductivity, configured to divide the processing tank 7 into a Li supply chamber 12 and a Li recovery chamber 13. Specifically, the electrolyte membrane 2 is a Li-conducting electrolyte... + Furthermore, it does not conduct Li contained in the non-aqueous solution containing Li. + Other metal ions M n+ The electrolyte is preferably an electron-nonconducting electrolyte. - More preferably, the electrolyte membrane 2 is a ceramic electrolyte possessing these properties. Specifically, lithium lanthanum titanium oxide (La) can be listed as an example. 2 / 3-x Li 3x TiO3 (also known as LLTO), etc. This electrolyte membrane 2 has lattice defects at a certain ratio. Due to the small size of these lattice defect sites, therefore, except for Li... + Other metal ions M n+ The diameter of Li + Large but not conductive.

[0052] Ion exchange membrane 31 is configured to divide the processing tank 7 into a first electrode chamber 11 and a Li supply chamber 12, and to conduct at least one cation other than lithium ions, such as H+. + Therefore, water (H2O) from the aqueous solution S1 in the first electrode chamber 11 is supplied to the Li-containing non-aqueous solution FS in the Li supply chamber 12. + The ion exchange membrane 31 is disposed at a sufficient distance from the electrolyte membrane 2, but preferably the distance is small. By suppressing the gap between the first electrode 41 and the second electrode 42 disposed between the electrolyte membrane 2 and the ion exchange membrane 31, the electric field generated relative to the applied voltage implemented by the power supply 5 can be enhanced. To make the ion exchange membrane 31 resistant to organic solvents contained in the non-aqueous solution FS containing Li, cation exchange membranes that allow cations to pass through while blocking anions, monovalent cation-selective ion exchange membranes that allow only monovalent cations to pass through, and bipolar monovalent ion-selective ion exchange membranes that allow monovalent ions to pass through can be used. Furthermore, in the aqueous solution S1 containing H+, ... + In the case of neutral or alkaline aqueous solutions containing cations other than metal ions, in order to prevent the metal ions from migrating to the Li-containing non-aqueous solution FS, it is preferable that the ion exchange membrane 31 is used to selectively conduct H+. + Hydrogen ion selective permeation membrane (proton conduction membrane) or bipolar membrane for hydrolysis. Alternatively, if the aqueous solution S1 is an aqueous solution of calcium hydroxide (Ca(OH)2) containing metal ions with a valence of 2 or higher, a monovalent cation selective permeation membrane that allows the passage of monovalent ions can be used as the ion exchange membrane 31.

[0053] These ion exchange membranes can utilize known ion exchange membranes. For example, Nafion (registered trademark) can be used as a proton conduction membrane and cation exchange membrane; NEOSEPTA BP-1E (manufactured by ASTOM Co., Ltd.) can be used as a bipolar membrane for hydrolysis; SELEMION (registered trademark) CMV, CMVN, CMTE (manufactured by AGC Engineering Co., Ltd.) and NEOSEPTA CSE (manufactured by ASTOM Co., Ltd.) can be used as cation exchange membranes; SELEMION (registered trademark) CSO (manufactured by AGC Engineering Co., Ltd.) and CXP-S (manufactured by ASTOM Co., Ltd.) can be used as monovalent cation selective permeable ion exchange membranes; and NEOSEPTACIMS (manufactured by ASTOM Co., Ltd.) can be used as a bipolar monovalent ion selective permeable ion exchange membrane.

[0054] The first electrode 41 and the second electrode 42 are electrodes used to apply a voltage that generates a low potential difference between the two sides of the ion exchange membrane 31 and the electrolyte membrane 2, respectively. Therefore, electrodes 41 and 42 are disposed in each of the chambers 11 and 13 at both ends of the processing tank 7.

[0055] like Figure 1 As shown, the first electrode 41 can be separately disposed from the ion exchange membrane 31 within the first electrode chamber 11, allowing the aqueous solution S1 to make overall contact with the surface of the ion exchange membrane 31. On the other hand, the shorter the distance between the first electrode 41 and the second electrode 42, the stronger the electric field generated relative to the applied voltage implemented by the power supply 5. Therefore, it is preferable to keep the distance between the first electrode 41 and the ion exchange membrane 31 short in a way that does not make the distance too large. Preferably, the first electrode 41 has a mesh-like shape or similar shape through which liquid passes, so that the aqueous solution S1 in contact with the surface of the ion exchange membrane 31 within the first electrode chamber 11 is continuously replaced. The first electrode 41 is preferably arranged parallel to the second electrode 42, such that it applies voltage to a larger area of ​​the electrolyte membrane 2 together with the second electrode 42. The first electrode 41 is formed of an electrode material that is electronically conductive and stable in the aqueous solution S1 when a voltage is applied during operation of the lithium recovery device 1. Regarding the material constituting the first electrode 41, when the aqueous solution S1 is pure water or an alkaline aqueous solution, it is preferable to have catalytic activity for the reaction of the following formula (1), and when the aqueous solution S1 is a neutral or acidic aqueous solution, it is preferable to have catalytic activity for the reaction of the following formula (5). In addition, it is preferable that the material is easy to process into the shape of the first electrode 41. Platinum (Pt) is preferred as such an electrode material, for example.

[0056] [Chemical Formula 2]

[0057] The second electrode 42 is disposed facing the electrolyte membrane 2 in the Li recovery chamber 13, either in contact with or separated from it. Preferably, it is disposed parallel to and close to the electrolyte membrane 2. More preferably, as shown below... Figure 1 As shown, it is in contact with the electrolyte membrane 2. This second electrode 42 is preferably sized such that a voltage is applied to a large area of ​​the electrolyte membrane 2. On the other hand, it is preferable to have a porous structure such as a mesh through which liquid passes, such as contacting the Li recovery aqueous solution RS with a sufficient area of ​​the side (back side) of the electrolyte membrane 2 on the Li recovery chamber 13 side, or to continuously replace the Li recovery aqueous solution RS in contact with the back side of the electrolyte membrane 2 within the Li recovery chamber 13. In addition, the second electrode 42 can be formed directly on one side of the electrolyte membrane 2, or it can be fixed to the processing tank 7 or the like by a clamp in contact with the electrolyte membrane 2. The second electrode 42 is formed of an electrode material that has electronic conductivity and is stable when a voltage is applied in the Li recovery aqueous solution RS, including after the operation of the lithium recovery device 1 (after Li recovery). For the material constituting the second electrode 42, it is preferable to be a material that has catalytic activity for the reaction of the following formula (4), and when it is set in contact with the electrolyte membrane 2, it is even more preferable to be a material that has catalytic activity for the reaction of the following formula (3). In addition, it is preferable that the material is easy to process into the shape of the second electrode 42. As such electrode material, platinum (Pt) is preferred, or carbon (C), copper (Cu), nickel (Ni) or stainless steel that are stable at a potential lower than that generated by the reaction of the following formula (4) can also be used, and materials on which Pt particles that function as catalysts are supported on these surfaces are more preferred.

[0058] [Chemical Formula 3]

[0059] Power supply 5 is a DC power supply device, connected between electrodes 41 and 42 with the Li recovery chamber 13 side as the negative terminal. That is, the positive terminal of power supply 5 is connected to the first electrode 41, and the negative terminal is connected to the second electrode 42. Power supply 5 applies voltage between the two sides of ion exchange membrane 31 and electrolyte membrane 2, respectively, causing the H2O contained in aqueous solution S1 to... + It migrates towards the Li-containing non-aqueous solution FS, and also causes the electrolyte membrane 2 to generate Li for conduction. + The potential gradient.

[0060] The treatment tank 7 is made of a material that will not dissolve, corrode, or deteriorate even when in contact with the non-aqueous solution FS containing Li and the aqueous solution RS for Li recovery, including after the operation of the lithium recovery unit 1 (after Li recovery). For example, the aqueous solution RS for Li recovery is an aqueous solution of lithium hydroxide (LiOH). Such materials can be, for example, glass, stainless steel, PP (polypropylene), or PEEK (polyether ether ketone) resin. Furthermore, the treatment tank 7 only needs to have a volume corresponding to the required processing capacity; its shape and other characteristics are not particularly limited.

[0061] The water supply device 81 is a device that supplies water to the first electrode chamber 11. During operation, the water in the aqueous solution S1 decreases due to the reaction of formula (1) or formula (5), and therefore it is replenished. The water supply device 81 can supply pure water, aqueous solution S1, or ionic compounds, and can adjust the pH value and conductivity of the aqueous solution S1. Furthermore, in Figure 1 The image shows a water supply device 81 supplying water from above the treatment tank 7, but this is only a schematic example and does not specify any particular configuration or structure.

[0062] The circulation device 82 is a circulation device that continuously circulates the Li-containing non-aqueous solution FS within the Li supply chamber 12 during operation. It includes a circulation tank located outside the processing tank 7 and a pump that circulates the Li-containing non-aqueous solution FS within this tank and within the Li supply chamber 12. That is, the structure of the circulation device 82 is not limited, as long as it is configured to circulate or supply the liquid in the circulation tank via a circulation path such as a hose communicating with the Li supply chamber 12. Furthermore, in Figure 1 In the diagram, a circulation device 82 is shown below the treatment tank 7, supplying and discharging the Li-containing non-aqueous solution FS from the bottom of the treatment tank 7. This is only an illustrative example and does not specify a particular configuration or structure. The circulation device 83 is similar. Furthermore, the circulation device 82 continuously replaces the Li-containing non-aqueous solution FS in contact with the electrolyte membrane 2, stirring the Li-containing non-aqueous solution FS within the Li supply chamber 12, and further replenishing the liquid volume in the Li supply chamber 12 as needed. Moreover, the circulation device 82 can supply Li-containing non-aqueous solution FS with a volume larger than that of the Li supply chamber 12 of the treatment tank 7, suppressing the Li content of the Li-containing non-aqueous solution FS during operation. + The concentration decreases. As described above, in this embodiment, in order to shorten the interval between the first electrode 41 and the second electrode 42, it is preferable that the distance between the ion exchange membrane 31 and the electrolyte membrane 2 is not long, that is, the volume of the Li supply chamber 12 is not large. Alternatively, the circulation device 82 can be a stirrer 8 with a screw rotating inside the Li supply chamber 12 (see [reference]). Figure 12 ), thus becoming the required structure.

[0063] The circulation device 83 is a circulation device that continuously replaces the Li recovery aqueous solution RS within the Li recovery chamber 13 and replenishes the liquid volume in the Li recovery chamber 13 as it decreases. It can have the same structure as the circulation device 82. During operation, the water in the Li recovery aqueous solution RS decreases due to the reaction in formula (4), and the circulation device 83 replenishes the decreased amount. Furthermore, the circulation device 83 stirs the Li recovery aqueous solution RS within the Li recovery chamber 13 by continuously replacing the Li recovery aqueous solution RS that is in contact with the electrolyte membrane 2 and the second electrode 42. The circulation device 83 may also include a system that allows the Li in the Li recovery aqueous solution RS to be continuously replaced. + A sedimentation tank for settling and a filter to prevent precipitate from returning to the Li recovery chamber 13. Alternatively, the circulation device 83 can be a water supply device, such as a water supply device 81, that supplies water to the Li recovery chamber 13, and can also be equipped with an agitator 8 having a screw rotating inside the Li recovery chamber 13 (see reference). Figure 12 ).

[0064] The lithium recovery device 1 may include a liquid level sensor or similar device to sense changes in the liquid volume in each of chambers 11, 12, and 13 during operation. Additionally, the lithium recovery device 1 may include a pH meter to measure the pH values ​​of the aqueous solutions S1 and RS during operation.

[0065] Furthermore, during operation, if carbon dioxide (CO2) in the air accidentally dissolves in the Li recovery aqueous solution RS and precipitates lithium carbonate (Li2CO3), the conductivity of the Li recovery aqueous solution RS decreases, which is undesirable. Therefore, to prevent this situation, it is preferable that the lithium recovery device 1 is configured so that the Li recovery aqueous solution RS is not exposed to air. In addition, during operation, O2 is generated from the first electrode chamber 11 and H2 is generated from the Li recovery chamber 13 through the reactions of formula (1) or formula (5) and formula (4), respectively. Therefore, from a safety perspective, it is preferable to have an exhaust unit to exhaust these gases in a way that does not fill the interior. Moreover, if the non-aqueous solution FS containing Li contains a volatile organic solvent, flammable, combustible, or toxic gases such as ethylene (C2H4) and propylene (C3H6) may be generated from the Li supply chamber 12. Therefore, from a safety perspective, it is preferable to have a unit that recovers these gases in a way that does not fill the interior and does not leak. Therefore, it is preferable that the lithium recovery device 1 exhausts the gas generated from the liquid S1, FS, and RS to the outside of the processing tank 7 without allowing outside air to flow in, for example, by installing one-way valves in chambers 11, 12, and 13 of the processing tank 7.

[0066] The lithium recovery device 1 may also include a heating device and a cooling device for heating or cooling at least one of the Li recovery aqueous solution RS and the Li-containing non-aqueous solution FS. The heating device and cooling device control the temperature of one of the liquids RS and FS, and via that one, control the temperature of the other, the electrolyte membrane 2. The heating device and cooling device can be any known device for heating or cooling liquids, such as an immersion type (immersion type) for the Li recovery aqueous solution RS immersed in the Li recovery chamber 13, or a device for heating or cooling the liquids RS and FS in the circulation tanks of the circulation devices 82 and 83, preferably having a temperature control function. The heating device and cooling device only need to maintain the electrolyte membrane 2 at a predetermined temperature; it is not necessary for the Li recovery aqueous solution RS and the Li-containing non-aqueous solution FS to have uniform liquid temperatures, but rather to ensure that they are above their freezing points and below their boiling points. As will be described later, the higher the temperature of the electrolyte membrane 2, the more Li... + The faster the movement within the electrolyte membrane 2, the better. On the other hand, in the case where the Li-containing non-aqueous solution FS contains a highly volatile organic solvent, it is preferable to suppress the temperature rise of the electrolyte membrane 2 in conjunction with voltage application (operation).

[0067] (Lithium recovery methods) Reference Figure 2 The lithium recovery method according to the first embodiment of the present invention will be described below. The lithium recovery method according to this embodiment is performed by a lithium recovery apparatus 1 in the following manner. Furthermore, in Figure 2 The water supply device 81 and the circulation devices 82 and 83 are omitted in the text.

[0068] In the lithium recovery device 1, the power supply 5 applies a positive voltage V1 (+V1) to the first electrode 41 relative to the second electrode 42. With the application of voltage +V1, the following reaction occurs in the aqueous solution S1 of the first electrode chamber 11. Near the first electrode 41, hydroxide ions (OH-) in the water (H2O) react... - The reaction described in equation (1) produces water (H2O) and oxygen (O2), resulting in the electron e. - Released to the first electrode 41. However, in the case where the aqueous solution S1 is a neutral or acidic aqueous solution, instead of the reaction of the following formula (1), H2O undergoes the reaction of the following formula (5) to generate H. + And O2. Accompanied by OH - The reduction or H + To maintain charge balance, the increase in hydrogen ions (H2O) leads to the formation of H2O. + The reaction of the following formula (6) involves the movement of the Li-containing non-aqueous solution FS through the ion exchange membrane 31 to the Li supply chamber 12. Furthermore, in each formula, hydrogen ions (H+) dissolved in the organic solvent are... + ) is represented as H + (non-aq.), other ions (H+ OH - () represents ions that are dissolved in water or aqueous solutions.

[0069] [Chemical Formula 4]

[0070] In the Li-containing non-aqueous solution FS of the Li supply chamber 12, by applying a voltage +V1, an electric field is generated from the ion exchange membrane 31 side to the electrolyte membrane 2 side. The cations in the Li-containing non-aqueous solution FS, namely Li... + M n+ It is attracted to the surface (surface) of the Li supply chamber 12 side of the electrolyte membrane 2 by electrostatic attraction. Additionally, H... + The aqueous solution S1 from the first electrode chamber 11 moves over (reaction of equation (6)). In order to maintain charge balance, Li in the non-aqueous solution FS containing Li moves over from the first electrode chamber 11. + The reaction of formula (7) in which lithium ions (Li) dissolved in an organic solvent move into electrolyte membrane 2. Furthermore, in formula (7), lithium ions (Li) dissolved in an organic solvent... + ) is represented as Li + (non-aq.).

[0071] [Chemical Formula 5]

[0072] On the other hand, in the Li recovery aqueous solution RS of Li recovery chamber 13, the following reaction occurs upon the application of voltage +V1. Near the second electrode 42, electrons are supplied by H2O in the Li recovery aqueous solution RS. - The reaction shown in equation (4) produces hydrogen (H2) and OH. - In the aqueous solution RS used for Li recovery, OH- is present. - To maintain charge balance, Li in electrolyte membrane 2 increases. + The reaction of equation (3) is transferred to the aqueous solution RS for Li recovery. In the aqueous solution RS for Li recovery, the reaction of equation (3) and the reaction of equation (4) are combined to produce the reaction of equation (8).

[0073] [Chemical Formula 6]

[0074] From the reaction in equation (7) to the reaction in equation (3), that is, the Li in the non-aqueous solution containing Li in FS + Invading from the surface of electrolyte membrane 2, Li + Li moving in electrolyte membrane 2 and in electrolyte membrane 2 +The Li recovery aqueous solution RS is moved as follows. With the application of voltage +V1, as in equation (7), Li in the Li-containing non-aqueous solution FS is reacted. + The lattice defect sites on the Li supply chamber 12 side of the electrolyte membrane 2 are penetrated. Then, by applying a voltage +V1, the electrolyte membrane 2 has a lower potential gradient on the opposite side (Li recovery chamber 13 side), thus allowing the Li to penetrate the lattice defect sites on the surface. + The crystal jumps (jumps) to lattice defect sites near the deeper side of electrolyte membrane 2. Thus, Li + The Li repeatedly moves from lattice defect sites on the electrolyte membrane 2 to nearby lattice defect sites, and finally, as a reaction of equation (3), moves from the lattice defect sites on the back side into the Li recovery aqueous solution RS. Then, the Li passes through the lattice defect sites on the surface of the electrolyte membrane 2. + It moves deeper into the electrolyte membrane 2, and adsorbs another Li into the vicinity of the vacated lattice defect site. + Or Li in non-aqueous solutions of Li FS + Infiltrate them, these Li + Similarly, it moves within electrolyte membrane 2.

[0075] In the lithium recovery method according to this embodiment, the reaction of formula (1) or formula (5) and the reaction of formula (4) occur when the voltage V1 is above the voltage of the water electrolysis reaction, so that Li + It moves within electrolyte membrane 2. The voltage of the electrolysis reaction that produces water (electrolysis voltage) is +1.229V (25°C) when the aqueous solution S1 and the Li recovery aqueous solution RS have the same pH value (hydrogen ion concentration). In practice, based on the electrode performance of determining the electrode reaction overvoltage of electrodes 41 and 42, the voltage V1 needs to be set to a value several hundred mV larger than the theoretical voltage of 1.229V. Furthermore, the higher the pH value of the Li recovery aqueous solution RS relative to the aqueous solution S1, the greater the electrolysis voltage becomes.

[0076] Furthermore, the larger the voltage V1, the greater the amount of each reaction in equation (1) or (5) and the reaction in equation (4), and consequently, the faster the reactions in equation (7) and (3). Additionally, the electric field generated in the Li-containing non-aqueous solution FS in the Li supply chamber 12 becomes stronger, and the Li... + The concentration of Li is drawn closer to the surface of electrolyte membrane 2, resulting in a relatively high concentration. Furthermore, within electrolyte membrane 2, the potential gradient between its two surfaces increases, leading to a higher concentration of Li. + The amount of movement per unit time (Li) + (Mobility) increases. Additionally, when the potential difference between the two surfaces of electrolyte membrane 2 is such that a portion of the metal ions constituting electrolyte membrane 2 is reduced (e.g., if electrolyte membrane 2 is LLTO, then Ti...), the potential difference between the two surfaces of electrolyte membrane 2 and the surface of electrolyte membrane 2 increases.4+ +e - →Ti 3+ When the voltage is above a certain value, the electrolyte membrane 2 can conduct electrons e from the Li recovery chamber 13 side to the Li supply chamber 12 side. - As a result, since most of the electrical energy provided is consumed by electrons... - The conduction of Li is consumed, therefore Li + The voltage dependence of mobility decreases, Li + The energy efficiency of the movement decreases sharply (see Patent Document 2). In particular, this phenomenon is more likely to occur for transition metal ions among the metal ions constituting the electrolyte membrane 2.

[0077] In the lithium recovery apparatus 1 according to this embodiment, since at least the first electrode 41 of the first electrode 41 and the second electrode 42 are disposed separately from the electrolyte membrane 2, the potential difference between the two sides of the electrolyte membrane 2 is suppressed to be small relative to the voltage V1, and the electrolyte membrane 2 does not easily exhibit electronic conductivity (see Patent Document 2). However, when the voltage V1 is increased to a certain extent, the potential difference between the two sides of the electrolyte membrane 2 reaches the potential difference at which the electrolyte membrane 2 exhibits electronic conductivity, so it is preferable to set the voltage V1 to be less than such a voltage. The relationship between the voltage V1 and the potential difference between the two sides of the electrolyte membrane 2 depends on the spacing between the first electrode 41 and the ion exchange membrane 31, the spacing between the second electrode 42 and the electrolyte membrane 2, the spacing between the ion exchange membrane 31 and the electrolyte membrane 2 (the length of the Li supply chamber 12), and the electronic conductivity of the aqueous solution S1 and the Li recovery aqueous solution RS, respectively. In particular, when Li + The recovery of Li is carried out using an aqueous solution of RS. + As the concentration (LiOH concentration) increases, the electronic conductivity of the Li recovery aqueous solution RS also increases, and the potential difference between the two sides of the electrolyte membrane 2 approaches and increases with voltage V1. Therefore, it is preferable to set voltage V1 by also considering the electronic conductivity of the Li recovery aqueous solution RS during operation.

[0078] Furthermore, in Li recovery using electrodialysis, because Li + Mobility by Li + The diffusion rate is limited by the surface of the electrolyte membrane on the supply side, therefore, when the Li in the solution on the supply side... + At low concentrations, even with increased applied voltage (V1) across the electrolyte membrane, Li + The mobility is also not easily increased. In this embodiment, as described above, the Li in the Li-containing non-aqueous solution FS generated in the Li supply chamber 12 is made to... + The concentration is relatively higher near the surface of electrolyte membrane 2, which can improve energy efficiency.

[0079] Li+ In addition to the voltage V1, the movement within the electrolyte membrane 2 increases rapidly with increasing temperature. Therefore, a high temperature for the electrolyte membrane 2 is preferred. Furthermore, the resistance of the aqueous solution S1 and the aqueous solution RS for Li recovery decreases with increasing temperature. The applicable temperature range for the electrolyte membrane 2 is above the freezing point and below the boiling point of liquids S1, FS, and RS, preferably above 20°C.

[0080] In the lithium recovery method of the present invention, as the operating time passes, the aqueous solution S1 in the first electrode chamber 11 decreases due to the reaction of formula (1) or formula (5), and the aqueous solution RS for Li recovery in the Li recovery chamber 13 decreases due to the reaction of formula (4). Additionally, sometimes the non-aqueous solution FS containing Li in the Li supply chamber 12 decreases due to the evaporation of organic solvents. Therefore, it is preferable, for example, to detect the liquid level using a liquid level sensor or to set a timer to operate the water supply device 81 and the circulation devices 82 and 83 in a manner that maintains the liquid volume in chambers 11, 12, and 13. In the lithium recovery device 1, it is preferable that the liquid levels in chambers 11, 12, and 13 are consistent during operation. Furthermore, as the operating time passes, the Li content in the aqueous solution RS for Li recovery decreases. + As the concentration increases, the pH value rises, thus increasing the pH value of the aqueous solution S1 accordingly can suppress the increase in electrolysis voltage. Therefore, for example, during operation, an alkali such as sodium hydroxide (NaOH) is supplied to the first electrode chamber 11.

[0081] For the Li recovery aqueous solution RS in the Li recovery chamber 13 and the circulation tank of the circulation device 83 after operation, for example, the water can be evaporated to concentrate Li, and then lithium carbonate (Li2CO3) can be generated by bubbling with carbon dioxide (CO2) or the like, and precipitated, thereby recovering Li. Alternatively, the Li recovery aqueous solution RS can be cooled or the water evaporated to generate lithium hydroxide (LiOH) in a supersaturated state, and precipitated, thereby recovering Li. In addition, Li can also be... + Lithium carbonate and other substances precipitate in the precipitation tank of the circulation device 83. This structure helps to suppress the high pH value of the Li recovery aqueous solution RS during the operation of the lithium recovery device 1.

[0082] Similarly, Li can be extracted from the Li supply chamber 12 and the Li-containing non-aqueous solution FS in the circulation tank of the circulation device 82 after the operation is completed. + Other metal ions M n+ The organic solvents are recovered using their respective known methods.

[0083] In this embodiment, the aqueous solution S1 contained in the first electrode chamber 11 can be an aqueous solution other than pure water as described above. The aqueous solution S1 contains H+ ions.+ In the case of neutral or alkaline aqueous solutions containing cations other than metal ions, metal ions can react with H+. + The lithium is supplied from the aqueous solution S1 to the non-aqueous solution FS containing Li. However, depending on the type of metal ions, they sometimes precipitate without dissolving during transport from the aqueous solution S1 to the non-aqueous solution FS, clogging the surface of the ion exchange membrane 31 on the Li supply chamber 12 side and reducing efficiency. Furthermore, when supplying metal ions from the aqueous solution S1 to the non-aqueous solution FS containing Li, the organic solvent is recovered from the non-aqueous solution FS after operation, resulting in sometimes low efficiency. Therefore, as described above, in the lithium recovery device 1, it is preferable to use metal ions that do not permeate the aqueous solution S1, i.e., only those permeating from the aqueous solution S1 through H2O. + The proton-conducting membrane or bipolar membrane is used in ion exchange membranes 31.

[0084] Alternatively, by making metal ions react with H + When both move from the aqueous solution S1 to the Li-containing non-aqueous solution FS, the metal ions contained in the aqueous solution S1 are Li. + In addition to the metal ions that pass through the ion exchange membrane 31, the preferred metal ions are those that dissolve in ionic form even in a non-aqueous solution containing Li (FS). For example, metal ions that are similar to Li... + Similarly, PF6 - BF4 - Na, as a counterion ion + This allows the aqueous solution S1 to be either sodium hydroxide (NaOH) or sodium chloride (NaCl). However, when aqueous solution S1 contains Cl... - Over time, platinum chloride (PtCl2) forms on the surface of the first electrode 41, which is made of Pt, thereby impairing the high catalytic activity of Pt and increasing the electrode reaction overvoltage. Therefore, the aqueous solution S1 containing Cl... - In this case, it is preferable to keep the concentration low. When the aqueous solution S1 is an aqueous solution of NaOH or NaCl, by applying voltage +V1, the H₂O in the aqueous solution S1 reacts with the H₂O... + The migration to the non-aqueous Li-containing FS (reaction of equation (6)) is similar, Na + It moves through ion exchange membrane 31 to the Li-containing non-aqueous solution FS. Furthermore, it allows metal ions (e.g., Na+) to migrate. + ) and H +When the aqueous solution S1 moves together to the non-aqueous solution FS containing Li, as the operating time progresses, the aqueous solution S1 decreases in pH value not only through the reaction of formula (1) or formula (5) but also through the reduction of metal ions. Therefore, as needed, during operation, not only pure water can be supplied through the water supply device 81, but also NaOH or the like can be supplied to the first electrode chamber 11 in order to maintain or increase the pH value of the aqueous solution S1.

[0085] In this embodiment, the medium for Li recovery contained in the Li recovery chamber 13 is not limited to water or aqueous solution, but can also be a non-aqueous solution. The non-aqueous solution RSA for Li recovery is as long as it contains lithium ions (Li... + The solution can be a non-aqueous solution that dissolves in the state of Li, and is used in organic solvents such as EC containing Li non-aqueous solutions as Li. + PF6, an anti-counterion - Plasma A n- The non-aqueous solution, preferably, is similar to the aqueous solution RS for Li recovery and does not contain Li. + Other than metal ions. The non-aqueous RSA for Li recovery can be a non-aqueous solution of Li salts such as LiPF6, or a non-aqueous solution of hexafluorophosphate (HPF6), tetrafluoroboric acid (HBF4), etc. Furthermore, the second electrode 42 is formed of an electrode material that is stable even when a voltage is applied in the non-aqueous RSA for Li recovery. When the non-aqueous RSA for Li recovery is housed in the Li recovery chamber 13, by applying a voltage +V1, Li in the electrolyte membrane 2 reacts in the non-aqueous RSA for Li recovery, similar to the aqueous RSA for Li recovery. + The reaction of the following equation (9) is moved. Furthermore, as H... + When the salts such as HPF6 and HBF4 are fully dissolved in the non-aqueous RSA for Li recovery, H2 is generated by the reaction of formula (4) near the second electrode 42. Furthermore, in the non-aqueous RSA for Li recovery, the anion A... n- In Li + The nearby counter ions maintain a neutral charge without change.

[0086] [Chemical Formula 7]

[0087] (Example 1) As described above, when the non-aqueous solution RSA for Li recovery is contained in the Li recovery chamber 13, metallic lithium can be recovered within the Li recovery chamber 13 instead of as Li. + The state. For example... Figure 3As shown, the lithium recovery apparatus 1A according to a modified example of the first embodiment of the present invention has a second electrode 42A disposed separately from the electrolyte membrane 2, and a non-aqueous solution RSA for Li recovery is contained in the Li recovery chamber 13. Figure 1 Similarly, the lithium recovery device 1A involved in the embodiment shown in this modification may have a water supply device 81 and circulation devices 82, 83 (illustrations omitted).

[0088] In this modified example, the potential of the second electrode 42A is Li + A voltage of +V1 is applied below the reduction potential (-3.05V vs. SHE). Therefore, in the non-aqueous RSA for Li recovery, in addition to the reaction shown in equation (9), an electron-donating reaction also occurs near the second electrode 42A. - To restore Li + The reaction is as follows (10). As a result, since metallic Li is deposited on the surface of the second electrode 42A, the recovery of Li after operation is easy. In this modified example, it is preferable that the potential of the organic solvent used for Li recovery, which is a non-aqueous RSA, is lower than that of the second electrode 42A, i.e., lower than that of Li. + Organic solvents with a reduction potential significantly lower than a certain level should be avoided from undergoing reduction decomposition by applying a voltage of +V1. Examples include EC, PC, DMC, and NMP.

[0089] [Chemical Formula 8]

[0090] The second electrode 42A is formed of an electrode material that is electronically conductive and stable under voltage application in the non-aqueous RSA for Li recovery. The material constituting the second electrode 42A is further preferably catalytically active for the reaction of formula (10), and preferably facilitates the recovery of metallic Li deposited on the surface. Alternatively, the second electrode 42A can be formed of high-purity metallic Li, which facilitates Li recovery after operation. Preferably, the second electrode 42A, like the first electrode 41, has a mesh-like or similar shape, allowing for continuous replacement of the non-aqueous RSA for Li recovery that is in contact with the back side of the electrolyte membrane 2 within the Li recovery chamber 13. The second electrode 42A is separately disposed from the electrolyte membrane 2 within the Li recovery chamber 13, preferably arranged parallel to the electrolyte membrane 2.

[0091] Here, Li + The reduction potential of Ti is greater than that of the metal ions constituting electrolyte membrane 2 (if electrolyte membrane 2 is LLTO, then Ti 4+ +e - →Ti 3+The potential is low. Therefore, as... Figure 2 As shown, when the second electrode 42 is in contact with the electrolyte membrane 2, the surface of the electrolyte membrane 2 on the Li recovery chamber 13 side has the same potential as the second electrode 42, becoming a forced reduction potential lower than the reduction potential of the metal ions, thereby generating Ti. 4+ +e - →Ti 3+ This reduction reaction results in increased Joule heat loss due to electron conduction in the electrolyte membrane 2, significantly reducing energy efficiency. Furthermore, with the passage of time, metallic Li deposited on the surface of the second electrode 42 blocks the pores of the second electrode 42 and the surface of the Li recovery chamber 13 side of the electrolyte membrane 2, reducing Li... + Mobility. Therefore, after a certain operating time, it is necessary to remove metallic Li from the surface of the second electrode 42, which is not preferable in terms of productivity. Therefore, it is preferable that the second electrode 42A and the electrolyte membrane 2 are spaced apart, such that when voltage +V1 is applied, the surface of the electrolyte membrane 2 on the Li recovery chamber 13 side is higher than the reduction potential of the metal ions constituting the electrolyte membrane 2.

[0092] To recover metallic Li within the Li recovery chamber 13, Anions that do not contain anions can also be used. - The organic solvent is contained in the Li recovery chamber 13. In this case, since the organic solvent is not electronically conductive, a second electrode 42 is provided in contact with the electrolyte membrane 2, similar to the first embodiment. When the Li in the electrolyte membrane 2... + When the organic solvent moves into the Li recovery chamber 13 (reaction of formula (9)), it is immediately reduced (reaction of formula (10)). However, as mentioned above, the energy efficiency and productivity are poor. In addition, the organic solvent in the Li recovery chamber 13 is contained in order to prevent the precipitated metallic Li from being oxidized or burned. It can be any medium with low reactivity to Li (non-reactive), such as argon (Ar) gas.

[0093] (Second variation) The anion A contained in the non-aqueous solution of Li in FS n- Includes BF4 - TFSA - In the case of such water-soluble anions, the aqueous solution (water) S1 contained in the first electrode chamber 11 can also be used as a receiving site for anions from the non-aqueous solution FS containing Li. Therefore, as Figure 4 As shown, in a modified example of the first embodiment of the present invention, the lithium recovery device 1C replaces the ion exchange membrane 31 of the lithium recovery device 1 of the embodiment and has the function of conducting the anions A. n- The anion exchange membrane (first ion conduction membrane) 32. Additionally, with... Figure 1Similarly, the lithium recovery device 1C involved in the embodiment shown may have a water supply device 81 and circulation devices 82, 83 (not shown).

[0094] Anion exchange membrane 32 conducts water-soluble anions A contained in Li-containing non-aqueous solutions FS. n- At least one of the following. Separated by an anion exchange membrane 32 from the first electrode chamber 11 and the Li supply chamber 12, the Li supply chamber 12 contains anion A containing Li-containing non-aqueous aqueous solution FS. n- It can move into the aqueous solution S1 in the first electrode chamber 11. This makes the anion exchange membrane 32 resistant to the organic solvents contained in the non-aqueous solution FS containing Li. The anion exchange membrane 32 can be any known anion exchange membrane, such as SELEMION (registered trademark) AMV (manufactured by AGC Engineering Co., Ltd.) and NEOSEPTA ASE (manufactured by ASTOM Co., Ltd.). The configuration of the anion exchange membrane 32 in the lithium recovery device 1C and other structures are the same as those of the ion exchange membrane 31 in the described embodiment.

[0095] Similar to the embodiment described above, the aqueous solution S1 contained in the first electrode chamber 11 can be pure water or an acidic, neutral, or alkaline aqueous solution. However, it is preferable that it does not contain anions A present in the Li-containing non-aqueous solution FS and permeating through the anion exchange membrane 32. n- Metal ions, etc., react and generate precipitates.

[0096] Similar to the method implemented by the lithium recovery device 1 in the aforementioned embodiment, in the lithium recovery method implemented by the lithium recovery device 1C, the power supply 5 applies a positive voltage V1 (+V1) relative to the second electrode 42 to the first electrode 41. With the application of voltage +V1, O2 is generated in the aqueous solution S1 of the first electrode chamber 11, as in the aforementioned embodiment, by a reaction of formula (1) or formula (5) near the first electrode 41. In the lithium recovery device 1C, OH- ions in the aqueous solution S1 are also generated. - The reduction or H + To maintain charge balance, anion A from the Li-containing non-aqueous solution FS in the Li-supply chamber 12 occurs in the aqueous solution S1 to supply the Li-containing non-aqueous solution FS. n- The reaction of formula (11) occurs as it moves through anion exchange membrane 32. Furthermore, in formula (11), anion A dissolved in an organic solvent... n- Represented as A n- (non-aq.).

[0097] [Chemical Formula 9]

[0098] Similar to the aforementioned embodiment, in the Li-containing non-aqueous solution FS of the Li supply chamber 12, the Li in the Li-containing non-aqueous solution FS... + M n+ They are attracted to the surface of electrolyte membrane 2 due to electrostatic attraction. Additionally, anions A... n- The reaction decreases as the aqueous solution S1 moves toward the first electrode chamber 11 (equation (11)). In order to maintain charge balance, Li in the non-aqueous solution FS containing Li occurs near the surface of the electrolyte membrane 2. + The reaction of the following formula (7) moves into the electrolyte membrane 2.

[0099] [Chemical Formula 10]

[0100] On the other hand, in the Li recovery aqueous solution RS of Li recovery chamber 13, similar to the embodiment described above, the reaction of formula (4) occurs near the second electrode 42 to generate H2 and OH. - In order to maintain charge balance, Li in electrolyte membrane 2 undergoes [a process / action]. + The reaction of the following formula (3) is carried out by moving the aqueous solution RS to Li recovery. In this way, Li can be recovered by the lithium recovery device 1C in the same way as the lithium recovery device 1 according to the embodiment described above.

[0101] [Chemical Formula 11]

[0102] In this modified example, as the operating time progresses, the aqueous solution S1, in addition to decreasing in water through the reaction of formula (1) or formula (5), also decreases in water through the movement of anions A from the non-aqueous solution containing Li. n- Lower the pH value. Therefore, the pH value of the aqueous solution S1 can be adjusted during operation as needed.

[0103] Similar to the lithium recovery apparatus 1 described in the above embodiment, in the lithium recovery apparatus 1C, the non-aqueous solution RSA for Li recovery can also be housed in the Li recovery chamber 13. Furthermore, as in the modified example described in the lithium recovery apparatus 1A (see...), Figure 3 In that case, it can also have a second electrode 42A to recover metallic lithium.

[0104] According to the lithium recovery apparatus of the first embodiment and its modifications, a first electrode chamber is provided on the Li supply side of the Li supply chamber of the processing tank by an ion-conducting membrane. By containing water in the first electrode chamber, O2 can be generated from the water, thereby enabling the recovery of Li from non-aqueous solutions by electrodialysis.

[0105] [Second Implementation] In the lithium recovery apparatus according to the first embodiment, it is preferable to suppress the voltage applied between the two sides of the lithium-ion conductive electrolyte membrane in such a way that the potential difference of the lithium-ion conductive electrolyte membrane does not exhibit electronic conductivity. Therefore, the following structure is adopted to increase the voltage and improve the Li + The lithium-ion conductive electrolyte membrane does not exhibit electronic conductivity, thus improving the mobility. The lithium recovery apparatus and method according to the second embodiment of the present invention will be described below.

[0106] (Lithium recovery device) like Figure 5 As shown, the lithium recovery apparatus 1B according to the second embodiment of the present invention includes: an electrolyte membrane (lithium-ion conductive electrolyte membrane) 2; an ion exchange membrane (first ion conductive membrane) 31; a processing tank 7, which is divided into three chambers by the ion exchange membrane 31 and the electrolyte membrane 2 in the order of chambers 11, 12, and 13; a first electrode 41, which is disposed in the first electrode chamber (third chamber) 11 at one end of the processing tank 7; a third electrode 43, which is disposed in contact with the electrolyte membrane 2 in the Li recovery chamber (first chamber) 13 at the other end; a second electrode 42B, which is disposed separately from the third electrode 43; and a power supply 5B, which is connected between the electrodes 41 and 42B with the first electrode 41 as the positive electrode. The power supply 5B is composed of a first power supply 51 and a second power supply 52 connected in series with its negative electrode. The third electrode is connected to the negative electrode of the first power supply 51. An aqueous solution S1 is contained in the first electrode chamber (third chamber) 11, a non-aqueous solution containing Li FS is contained in the Li supply chamber (second chamber) 12, and an aqueous solution RS for Li recovery is contained in the Li recovery chamber (first chamber) 13. The lithium recovery device 1B may also include a water supply device 81 and circulation devices 82 and 83 as needed. Similar to the lithium recovery device 1 according to the first embodiment, the lithium recovery device 1B may also include a heating device, a cooling device, a liquid level sensor, a pH meter, an exhaust unit, etc. The lithium recovery device 1B according to this embodiment is configured relative to... Figure 1 The lithium recovery apparatus 1 according to the first embodiment shown has a power supply 5B consisting of two power supplies 51 and 52 connected in series. The second electrode 42B is separated from the electrolyte membrane 2 in the Li recovery chamber 13. Furthermore, a third electrode 43 is added to the Li recovery chamber 13, which is connected to the negative electrode of the first power supply 51 (the positive electrode of the second power supply 52) and is in contact with the electrolyte membrane 2.

[0107] The second electrode 42B is used to apply a voltage in pair with the first electrode 41, and also to form a potential lower than the back surface of the electrolyte membrane 2 in the Li recovery aqueous solution RS. Therefore, the second electrode 42B is arranged in the Li recovery chamber 13 facing the third electrode 43, without contacting the electrolyte membrane 2 and in contact with the electrolyte membrane 2, and preferably arranged parallel to the third electrode 43. Moreover, as will be described later, it is preferable that the second electrode 42B is arranged close to the third electrode 43 to a degree that will not cause a short circuit. In addition, it is preferable that the second electrode 42B has a mesh-like shape to increase the contact area with the Li recovery aqueous solution RS. The second electrode 42B is formed of an electrode material that has electronic conductivity and is stable when a voltage is applied in the Li recovery aqueous solution RS. Preferably, this material has catalytic activity for the reaction of the following formula (4). That is, the second electrode 42B can be made of the same electrode material as the second electrode 42 of the first embodiment.

[0108] [Chemical Formula 12]

[0109] The third electrode 43 is used to apply voltage between the two surfaces of the ion exchange membrane 31 and the electrolyte membrane 2, respectively, in pair with the first electrode 41. Additionally, it is used to make the potential of the surface of the electrolyte membrane 2 on the Li recovery chamber 13 side relatively high in the Li recovery aqueous solution RS. Therefore, the third electrode 43 is disposed facing each other in contact with or separately from the surface of the electrolyte membrane 2 on the Li recovery chamber 13 side, preferably closer to the electrolyte membrane 2, and more preferably in conjunction with the lithium recovery apparatus 1 according to the first embodiment (see...). Figure 1 The second electrode 42 also has a porous structure and is disposed in contact with the electrolyte membrane 2. The third electrode 43 is formed of an electrode material that is electronically conductive and stable when a voltage is applied in the aqueous solution RS for Li recovery. Preferably, this material has catalytic activity for the reactions of the following formula (1) and the following formula (3). Platinum (Pt) is preferred as such an electrode material, for example.

[0110] [Chemical Formula 13]

[0111] Power supply 5B is formed by connecting a first power supply 51 and a second power supply 52 in series. Power supplies 51 and 52 are both DC power supplies, similar to power supply 5 in the first embodiment. The positive terminal of the first power supply 51 is connected to the first electrode 41, and the negative terminal is connected to the third electrode 43, applying a voltage V1. The first power supply 51 applies a voltage between the two sides of the electrolyte membrane 2. Since the second power supply 52 is connected in series with the negative terminal of the first power supply 51, its positive terminal is connected to the third electrode 43, and its negative terminal is connected to the second electrode 42B. The second power supply 52 applies a voltage V2, creating a potential lower than that on the back side of the electrolyte membrane 2 in the Li recovery aqueous solution RS, thus suppressing the electronic conductivity of the electrolyte membrane 2.

[0112] (Lithium recovery methods) Reference Figure 6 The lithium recovery method according to the second embodiment of the present invention will be described below. The lithium recovery method according to this embodiment is performed using a lithium recovery apparatus 1B as follows. Furthermore, in Figure 6 The water supply device 81 and the circulation devices 82 and 83 are omitted in the text.

[0113] In this embodiment, voltage V1 is applied by the first power source 51 and voltage V2 is applied by the second power source 52 simultaneously. In the lithium recovery device 1B, the first power source 51 and the second power source 52, which are connected in series, can be regarded as a single power source 5B (see reference). Figure 5 Power supply 5B applies a positive voltage (V1+V2) relative to the second electrode 42B to the first electrode 41. Thus, in the aqueous solution S1 of the first electrode chamber 11 and the Li-containing non-aqueous solution FS of the Li supply chamber 12, reactions occur respectively as described in the first embodiment (see [reference]). Figure 2 The same reaction occurs. That is, in the aqueous solution S1, near the first electrode 41, the reaction of formula (1) or formula (5) occurs to generate O2, accompanied by the formation of H2O in the aqueous solution S1. + The reaction of formula (6) involves the movement of the Li-containing non-aqueous solution FS through the ion exchange membrane 31 and into the Li supply chamber 12. Furthermore, in the Li-containing non-aqueous solution FS, Li... + The reaction of the following formula (7) moves into the electrolyte membrane 2.

[0114] [Chemical Formula 14]

[0115] On the other hand, in the Li recovery aqueous solution RS of the Li recovery chamber 13, which is equipped with the second electrode 42B and the third electrode 43, the following reaction occurs. Near the second electrode 42B, under the application of a voltage (V1+V2) provided by the power supply 5B, H2O in the Li recovery aqueous solution RS is supplied with electrons (e). -This leads to the reaction shown in equation (4), which produces H2 and OH. - Additionally, simultaneously, the second power source 52 applies a positive voltage V2, with a predetermined magnitude based on voltage V1, to the third electrode 43 relative to the second electrode 42B. Thus, near the third electrode 43, OH- in the Li recovery aqueous solution RS... - The reaction of equation (1) occurs, causing electrons e to... - H2O and O2 are released to the third electrode 43. This reaction is slower than the reaction in equation (4) near the second electrode 42B due to the difference in applied voltage. Therefore, in the aqueous solution RS for Li recovery, when the reaction in equation (4) is added to the reaction in equation (1), OH... - Increase. Accompanying this, in order to maintain charge balance, Li in the electrolyte membrane 2 increases near the back side of the electrolyte membrane 2, i.e., near the third electrode 43. + The reaction of the following formula (3) is transferred. Additionally, in the aqueous solution RS for Li recovery, H is generated due to the reaction of the following formula (4) occurring near the second electrode 42B. + The reduction of cations and the excess of cations resulting from the reactions of equation (1) and (3) occurring near the third electrode 43 lead to a charge imbalance. To address this problem, Li + It moves rapidly from the vicinity of the third electrode 43 to the vicinity of the second electrode 42B. Furthermore, the relative magnitudes of voltage V1 and voltage V2 will be explained later.

[0116] [Chemical Formula 15]

[0117] In this embodiment, by applying voltage V2, a potential gradient is generated in the Li recovery aqueous solution RS, with the area near the third electrode 43 (electrolyte membrane 2) being positive and the area near the second electrode 42B being negative. Therefore, electrons e supplied from the second electrode 42B to the Li recovery aqueous solution RS... - Moving from the third electrode 43 on the back side of the electrolyte membrane 2 towards the positive terminal of the second power supply 52, the potential of the third electrode 43, i.e., the back side of the electrolyte membrane 2, is maintained at a relatively high level for O2 generation. This is because the O2 generation potential is higher than the reduction potential of the metal ions constituting the electrolyte membrane 2 (if the electrolyte membrane 2 is LLTO, then Ti...). 4+ +e - →Ti 3+ The potential is high, therefore no matter the potential difference between the two sides of electrolyte membrane 2, electrons e will not be conducted. -Therefore, the potential difference between the two sides of the electrolyte membrane 2 can be set to a large voltage that causes the electrolyte membrane 2 to reach a reduction potential greater than the applied voltage of at least one metal ion constituting the electrolyte membrane 2. In other words, if a voltage V1, which is such a large potential difference, is applied without applying a voltage V2, electrons e can be harvested from the negative electrode side (Li recovery chamber 13 side) (back side) of the electrolyte membrane 2. - This would reduce the metal ions. However, as described above in this embodiment, by applying voltage V2, the electrolyte membrane 2 does not reach the reduction potential of the metal ions, thus the electrolyte membrane 2 does not transfer electrons e. - Additionally, in the aqueous solution RS for Li recovery, Li is reacted through the aforementioned potential gradient. + Pulled closer to the vicinity of the second electrode 42B, causing the Li near the back side of the electrolyte membrane 2 to... + The concentration decreases. As a result, an effect occurs between the two sides of electrolyte membrane 2 due to Li... + The concentration gradient creates a large chemical potential difference, thus promoting the Li-terminal interstitial formation at lattice defect sites in electrolyte membrane 2. + The movement.

[0118] Li + As described in the first embodiment, the movement within the electrolyte membrane 2 increases with the greater the potential gradient of the electrolyte membrane 2, i.e., the greater the voltage V1 of the first power supply 51. + The movement within electrolyte membrane 2 is also as described above, with the Li in electrolyte membrane 2... + The greater the concentration gradient, the faster the reaction. Therefore, the stronger the electric field between the third electrode 43 and the second electrode 42B in the Li recovery aqueous solution RS, that is, the greater the voltage V2 of the second power supply 52, the easier the reaction of equation (3) becomes, and the more readily the Li in the electrolyte membrane 2 can be reacted. + The reaction proceeds rapidly towards the Li recovery aqueous solution RS. Furthermore, as the voltage V1 increases, the rate difference between the reaction in equation (4) and the reaction in equation (1) within the Li recovery aqueous solution RS also increases. - The rate of increase of Li increases faster, therefore the reaction in equation (3) accelerates, enabling the Li in electrolyte membrane 2 to... + The aqueous solution RS is moved towards Li recovery.

[0119] When the magnitude of voltage V2 is insufficient relative to the required voltage determined by voltage V1, current flows from the third electrode 43 to the negative terminal of the first power source 51, that is, the third electrode 43 acquires electrons e. -H2 is generated by the reaction of formula (4) in the vicinity. As a result, the electrolyte membrane 2 can exhibit electronic conductivity. Therefore, the voltage V2 is set to prevent current from flowing from the third electrode 43 to the negative electrode of the first power source 51. Theoretically, when the resistance between the first electrode 41 and the third electrode 43 is represented as R1, the resistance between the third electrode 43 and the second electrode 42B is represented as R2, the reaction resistance at the first electrode 41 caused by the reaction of formula (1) or formula (5) is represented as Ra, and the reaction resistance at the second electrode 42B caused by the reaction of formula (4) is represented as Rc, it is set in such a way that V2≧V1×[(R2+Rc) / (R1+Ra)] holds (see Patent Document 3). However, as the voltage V2 increases further, the current flowing from the second power source 52 to the third electrode 43 increases, and the increase in the generation of O2 near the third electrode 43 (reaction of formula (1)) and the generation of H2 near the second electrode 42B (reaction of formula (4)) exceeds that of Li. + As the amount of movement increases, energy efficiency decreases. Therefore, for example, a galvanometer can be connected in series with the third electrode 43 (the galvanometer is connected between the connection between the first power supply 51 and the second power supply 52 and the third electrode 43), and voltages V1 and V2 can be applied while measuring the current.

[0120] Similar to the first embodiment, the lithium recovery apparatus according to this embodiment may also contain a non-aqueous solution RSA for Li recovery (see reference 1) in the Li recovery chamber 13. Figure 3 In this case, electrodes 42B and 43 are formed of electrode materials that are stable even when a voltage is applied in the non-aqueous RSA for Li recovery. With the application of voltages +V1 and +V2, the reaction of equation (9) occurs near the third electrode 43 in the non-aqueous RSA for Li recovery, but when H... + When the amount of dissolved salts such as HPF6 and HBF4 is small, the reactions of formula (1) and formula (4) that generate O2 and H2 do not occur. Furthermore, since no O2 is generated near the third electrode 43, no current flows between the third electrode 43 and the positive electrode of the second power supply 52. ​​As described in the first embodiment, in the non-aqueous solution RSA for Li recovery, the anion A... n- In Li + The nearby counter ions maintain a neutral charge without change.

[0121] [Chemical Formula 16]

[0122] (Variation example) Similar to the variation of the first embodiment, the lithium recovery apparatus according to this embodiment may have an anion exchange membrane 32 as a first ion conduction membrane (see reference). Figure 4Furthermore, the lithium recovery apparatus according to this embodiment can contain a non-aqueous solution RSA for Li recovery in the Li recovery chamber 13, and can also recover metallic lithium in the Li recovery chamber 13. Therefore, the lithium recovery apparatus 1B has a second electrode 42A instead of the second electrode 42B (see reference). Figure 3 When voltages +V1 and +V2 are applied, the potential of the second electrode 42A is set to Li. + The reduction potential is below. At this time, as described in the modified example of the first embodiment, the voltage V2 is adjusted so that the potential of the surface of the electrolyte membrane 2 on the Li recovery chamber 13 side is higher than the reduction potential of the metal ions constituting the electrolyte membrane 2, that is, the potential of the third electrode 43 is higher than the reduction potential of the metal ions.

[0123] Similar to the first embodiment, the lithium recovery apparatus according to the second embodiment and its variations can recover Li from non-aqueous solutions and can also increase the amount of Li recovered per unit time by increasing the applied voltage.

[0124] [Third Implementation] In the lithium recovery apparatus according to the first embodiment, the processing tank is divided by an ion exchange membrane into a Li supply chamber opposite to the electrolyte membrane and a first electrode chamber located at the end. A first electrode is disposed in the first electrode chamber, and Li is removed by... + Other ions move through the ion exchange membrane, Li + Through an electrolyte membrane. Similarly, the Li recovery chamber side can also be separated by an ion exchange membrane, and a second electrode can be disposed in the end chamber. Hereinafter, the lithium recovery method according to the third embodiment of the present invention will be described.

[0125] (Lithium recovery device) like Figure 7As shown, the lithium recovery apparatus 1D according to the third embodiment of the present invention includes: an electrolyte membrane (lithium-ion conductive electrolyte membrane) 2; an ion exchange membrane (first ion conductive membrane) 31; a bipolar membrane (second ion conductive membrane) 33; a processing tank 7, which is divided into four chambers by the membranes 31, 2, and 33 in the order of chambers 11, 12, 13, and 14; a first electrode 41, which is disposed in the first electrode chamber (third chamber) 11 at one end of the processing tank 7; a second electrode 42C, which is disposed in the chamber (fourth chamber) 14 at the other end; and a power supply 5, which is connected between the electrodes 41 and 42C with the first electrode 41 as the positive electrode. The chamber (fourth chamber) 14 at the end of the processing tank 7, which is separated from the Li recovery chamber (first chamber) 13 by the bipolar membrane 33, is the second electrode chamber and is used to contain the aqueous solution S2. An aqueous solution S1 is contained in the first electrode chamber (third chamber) 11, a non-aqueous solution containing Li FS is contained in the Li supply chamber (second chamber) 12, and an aqueous solution RS for Li recovery is contained in the Li recovery chamber (first chamber) 13. The lithium recovery device 1D may also include, as needed, water supply devices 81 and 84 for supplying water (aqueous solutions S1 and S2) to chambers 11 and 14 respectively, and circulation devices 82 and 83 respectively provided in chambers 12 and 13. Similar to the lithium recovery device 1 according to the first embodiment, the lithium recovery device 1D may also include a heating device, a cooling device, a liquid level sensor, a pH meter, an exhaust unit, etc. The lithium recovery device 1D according to this embodiment is configured to... Figure 1 The lithium recovery apparatus 1 according to the first embodiment shown is supplemented with a bipolar membrane 33, and a second electrode chamber 14 is added to the end of the processing tank 7 on the Li recovery chamber 13 side, and a second electrode 42C is disposed in the second electrode chamber 14.

[0126] Aqueous solution S2 is a cation recovery aqueous solution for obtaining cations from the Li recovery aqueous solution RS in the Li recovery chamber 13 and / or an anion supply aqueous solution for supplying anions to the Li recovery aqueous solution RS. The ions supplied by aqueous solution S2 are based on ions passing through the second ion-conducting membrane 33. Similar to aqueous solution S1, aqueous solution S2 is, for example, pure water at the start of operation of the lithium recovery device 1D. Alternatively, in order to make ions (containing H) + and / or OH - The movement proceeds smoothly, and the aqueous solution S2 can be an acidic, neutral, or alkaline aqueous solution (electrolyte aqueous solution) with a certain degree of high electronic conductivity. Furthermore, after operation begins, it is preferable that the aqueous solution S2 does not have a high pH value relative to the aqueous solution S1 in the first electrode chamber 11 (S1 < S2), and more preferably a lower pH value. Therefore, it is preferable to use the same aqueous solution for both aqueous solutions S1 and S2, or to use a combination of aqueous solutions with a higher pH value for S1 than for S2, for example, making S1 a neutral aqueous solution and S2 an acidic aqueous solution.

[0127] The second ion-conducting membrane 33 is configured to divide the processing tank 7 into the Li recovery chamber 13 and the second electrode chamber 14, and does not conduct Li. + The aqueous solutions RS and S2 used for Li recovery contain Li-removing agents. + At least one ion other than H+. The second ion-conducting membrane 33 can be used to selectively conduct H+. + The proton-conducting membrane, conducting H + and OH - The bipolar membrane for hydrolysis is used in this embodiment. The bipolar membrane 33 faces the first electrode 41 with the anion exchange membrane as its side. Figure 7 (Left side of the image). The second ion-conducting membrane 33 is positioned at a sufficient distance from the electrolyte membrane 2, but preferably with a small distance. The second ion-conducting membrane 33 is also positioned to correspond to the pH values ​​of the Li recovery aqueous solution RS and the aqueous solution S2, including after operation begins. Similar to the first ion-conducting membrane 31, the second ion-conducting membrane 33 can be a known ion-conducting membrane.

[0128] like Figure 7 As shown, the second electrode 42C can be separately disposed from the bipolar membrane 33 within the second electrode chamber 14, allowing the aqueous solution S2 to make overall contact with the surface of the bipolar membrane 33. On the other hand, it is preferable to make the distance between the second electrode 42C and the bipolar membrane 33 shorter in a way that does not make the distance between the first electrode 41 and the second electrode 42C too large. In addition, it is preferable that the second electrode 42C is disposed in parallel with the electrolyte membrane 2. The second electrode 42C is formed of an electrode material that has electronic conductivity and is stable when a voltage is applied in the aqueous solution S2. Preferably, the material has catalytic activity for the reaction of the following formula (4). The other structures of the second electrode 42C are the same as those of the second electrode 42B in the second embodiment.

[0129] [Chemical Formula 17]

[0130] The water supply device 81 and the circulation devices 82 and 83 can have the same structure as in the first embodiment. Especially in this embodiment, in order to shorten the interval between the first electrode 41 and the second electrode 42C, it is preferable that the distance between the ion exchange membrane 31 and the electrolyte membrane 2, and the distance between the electrolyte membrane 2 and the bipolar membrane 33, are both short; that is, similar to the Li supply chamber 12, the volume of the Li recovery chamber 13 is not large. Through the circulation device 83, the Li recovery aqueous solution RS, which has a large volume relative to the Li recovery chamber 13, is circulated, thereby slowing down the loss of Li from the Li recovery aqueous solution RS. + The rate of increase in concentration. Therefore, it is possible to suppress the high pH value of the aqueous solution RS for Li recovery, and also to suppress the Li concentration rise between the two sides of the electrolyte membrane 2. +The reduction of chemical potential is achieved by the concentration gradient.

[0131] Water supply device 84 is a device that supplies water to the second electrode chamber 14. During operation, the water is reduced due to the reaction in aqueous solution S2 by formula (4), so it is replenished. Similar to water supply device 81, water supply device 84 can supply pure water, aqueous solution S2, or ionic compounds, and can adjust the pH value and conductivity of aqueous solution S2.

[0132] (Lithium recovery methods) Reference Figure 8 The lithium recovery method according to the third embodiment of the present invention will be described below. The lithium recovery method according to this embodiment is performed by the lithium recovery apparatus 1D in the following manner. Furthermore, in Figure 8 Water supply devices 81 and 84 and circulation devices 82 and 83 are omitted.

[0133] Similar to the first embodiment, in this embodiment, the power supply 5 applies a positive voltage V1 (+V1) relative to the second electrode 42C to the first electrode 41. The reactions in the aqueous solution S1 of the first electrode chamber 11 and the Li-containing non-aqueous solution FS of the Li supply chamber 12, respectively, caused by the application of voltage +V1, are the same as in the first embodiment. That is, in the aqueous solution S1, O2 is generated near the first electrode 41 by a reaction of formula (1) or formula (5), accompanied by the formation of H2O in the aqueous solution S1. + The reaction of formula (6) involves the movement of the Li-containing non-aqueous solution FS through the ion exchange membrane 31 and into the Li supply chamber 12. Furthermore, in the Li-containing non-aqueous solution FS, Li... + The reaction of the following formula (7) moves into the electrolyte membrane 2.

[0134] [Chemical Formula 18]

[0135] On the other hand, in the aqueous solution S2 of the second electrode chamber 14, where the second electrode 42C is disposed, the following reaction occurs upon the application of voltage +V1. Near the second electrode 42C, H2O in the aqueous solution S2 is supplied with electrons (e). - This leads to the reaction shown in equation (4), which produces H2 and OH. - Accompanied by OH - To maintain charge balance, OH... - The Li recovery aqueous solution RS moves through the bipolar membrane 33 into the Li recovery chamber 13, while the H2O in the Li recovery aqueous solution RS also moves through the membrane. + It migrates through the bipolar membrane 33 into the aqueous solution S2. Furthermore, in the aqueous solution RS for Li recovery, H... +The reduction and OH - To maintain charge balance, the Li in electrolyte membrane 2 increases, and Li... + The reaction of equation (3) is transferred to the Li recovery aqueous solution RS. Further, by applying a voltage +V1 in the Li recovery aqueous solution RS, an electric field is generated from the electrolyte membrane 2 side towards the bipolar membrane 33 side, and Li... + Due to electrostatic attraction, it moves away from the vicinity of the back side of electrolyte membrane 2.

[0136] [Chemical Formula 19]

[0137] Similar to the first embodiment, in the lithium recovery method of this embodiment, by making the voltage V1 above the electrolysis voltage, the reaction of formula (1) or formula (5) and the reaction of formula (4) occur, thereby Li + It moves within the electrolyte membrane 2. In this embodiment, since the second electrode 42C is in contact with the aqueous solution S2 in the second electrode chamber 14, the volume and concentration of the aqueous solution S2 are maintained by the water supply device 84 in such a way that its pH value does not change during operation, thereby making it easy to control the electrolysis voltage and suppress the applied voltage V1.

[0138] (Variation example) The lithium recovery apparatus 1C according to the modified example of the first embodiment (see reference) Figure 4 Similarly, the first ion-conducting membrane of the lithium recovery device 1D according to this embodiment can be an anion exchange membrane 32. Furthermore, the second ion-conducting membrane of the lithium recovery device 1D can be an anion exchange membrane. Similar to the anion exchange membrane 32, a known anion exchange membrane can be used as the second ion-conducting membrane. In this case, when the aqueous solution S2 contains OH-... - Other anions (e.g., Cl) - When the anion reacts with OH-, - The solution moves together to the Li recovery aqueous solution RS. It is undesirable to introduce OH- into the Li recovery aqueous solution RS. - When the second ion-conducting membrane is an anion exchange membrane and other anions are present, the aqueous solution S2 is preferably free of OH-. - Other than OH-, the anions are pure water or alkaline aqueous solutions. Alternatively, a monovalent anion-selective permeable ion exchange membrane that only allows the passage of monovalent anions can be used as the second ion-conducting membrane, and the aqueous solution S2 contains only ions other than OH-. - Other anions with a valence of 2 or higher (e.g., SO42-) 2- ).

[0139] Similar to the variations of the first embodiment, the lithium recovery apparatus according to this embodiment is capable of containing a non-aqueous solution RSA for Li recovery in the Li recovery chamber 13. For example... Figure 9 As shown, the lithium recovery device 1E involved in this modified example has an anion exchange membrane 34 serving as a second ion-conducting membrane. In this modified example, the aqueous solution S2 contains BF4. - Equally water-soluble and becomes Li in non-aqueous RSA for Li recovery. + The counterion anion A n- The anion exchange membrane 34 conducts the anion A. n- Similar to the anion exchange membrane 32, a known anion exchange membrane can be used. Furthermore, the lithium recovery device 1E can have an anion exchange membrane 32 as a first ion-conducting membrane (see reference). Figure 4 ).

[0140] The lithium recovery method of lithium recovery device 1E is similar to the method of lithium recovery device 1D according to the aforementioned embodiment (see reference). Figure 8 The same. In this variation, such as Figure 9 As shown, by applying voltage +V1, the anions A in aqueous solution S2... n- The Li moves through the anion exchange membrane 34 to the non-aqueous solution RSA for Li recovery. In the non-aqueous solution RSA for Li recovery, in order to maintain charge balance, the Li in the electrolyte membrane 2... + Move over here.

[0141] In this modified example, as the operating time progresses, the aqueous solution S2, in addition to reducing water through the reaction in equation (4), also decreases through the reaction of anion A. n- The pH value increases as the concentration decreases. Therefore, the pH value of the aqueous solution S2 can be adjusted during operation as needed.

[0142] The lithium recovery device 1E may have a bipolar membrane for hydrolysis or a proton-conducting membrane as a second ion-conducting membrane (see reference). Figure 8 In this case, in the non-aqueous solution RSA for Li recovery, via H... + Li moves towards the aqueous solution S2, and the Li in the electrolyte membrane 2... + Move over. Therefore, in order to fully dissolve the non-aqueous RSA as H in Li recovery. + Salts such as HPF6 and HBF4 can be added during operation as needed. + Salt.

[0143] Similar to the first embodiment, the lithium recovery apparatus according to the third embodiment and its variations can recover Li from non-aqueous solutions, and since the electrolysis voltage can be easily controlled, power consumption can be suppressed. Furthermore, since the electrodes do not come into contact with the Li recovery solution, especially when recovering Li in an organic solvent (a non-aqueous solution for Li recovery), the electrode material will not be contaminated in the Li recovery solution.

[0144] [Fourth Implementation] The lithium recovery apparatus according to the third embodiment, by having two power supplies as in the second embodiment and setting their respective voltages to appropriate values, can increase the amount of Li recovered per unit time. Hereinafter, the lithium recovery apparatus and lithium recovery method according to the fourth embodiment of the present invention will be described.

[0145] (Lithium recovery device) like Figure 10 As shown, the lithium recovery apparatus 1F according to the fourth embodiment of the present invention includes: an electrolyte membrane (lithium-ion conductive electrolyte membrane) 2; an ion exchange membrane (first ion conductive membrane) 31; a bipolar membrane (second ion conductive membrane) 33; a processing tank 7, which is divided into four chambers by membranes 31, 2, and 33 in the order of chambers 11, 12, 13, and 14; a first electrode 41, which is disposed in the first electrode chamber (third chamber) 11 at one end of the processing tank 7; a second electrode 42C, which is disposed in the second electrode chamber (fourth chamber) 14; a third electrode 43, which is disposed in contact with the electrolyte membrane 2 in the Li recovery chamber (first chamber) 13; and a power supply 5B, which is connected between electrodes 41 and 42C with the first electrode 41 as the positive electrode. The power supply 5B is composed of a first power supply 51 and a second power supply 52 connected in series with its negative electrode. The third electrode is connected to the negative electrode of the first power supply 51. An aqueous solution S1 is contained in the first electrode chamber (third chamber) 11, a non-aqueous solution containing Li FS is contained in the Li supply chamber (second chamber) 12, an aqueous solution RS for Li recovery is contained in the Li recovery chamber (first chamber) 13, and an aqueous solution S2 is contained in the second electrode chamber (fourth chamber) 14. The lithium recovery device 1F may also include water supply devices 81 and 84 and circulation devices 82 and 83, as needed. Similar to the lithium recovery device 1 according to the first embodiment, the lithium recovery device 1F may also include a heating device, a cooling device, a liquid level sensor, a pH meter, an exhaust unit, etc. (Refer to the lithium recovery device 1D according to the third embodiment...) Figure 7 Similarly, the lithium recovery device 1F according to this embodiment is configured to be the same as the lithium recovery device 1B according to the second embodiment (see...). Figure 5 A bipolar membrane 33 is added, a second electrode chamber 14 is added to the end of the processing tank 7, and a second electrode 42C is arranged in the second electrode chamber 14.

[0146] The elements of the lithium recovery device 1F according to this embodiment can have the same structure as those of the lithium recovery device 1B according to the second embodiment and the lithium recovery device 1D according to the third embodiment. In the lithium recovery device 1F, similar to the second electrode 42B in the second embodiment, the second electrode 42C is an electrode used to form a potential lower than the back side of the electrolyte membrane 2 in the Li recovery aqueous solution RS for Li recovery in the Li recovery chamber 13.

[0147] (Lithium recovery methods) Reference Figure 11 The lithium recovery method according to the fourth embodiment of the present invention will be described below. The lithium recovery method according to this embodiment is performed using a lithium recovery apparatus 1F as follows. Furthermore, in Figure 11 Water supply devices 81 and 84 and circulation devices 82 and 83 are omitted.

[0148] Compared with the second embodiment (see the second embodiment) Figure 6 Similarly, in this embodiment, voltage V1 is applied by the first power supply 51 and voltage V2 is applied by the second power supply 52 simultaneously. That is, the first power supply 51 and the second power supply 52 are connected in series (power supply 5B, reference...). Figure 10 A positive voltage (V1+V2) relative to the second electrode 42C is applied to the first electrode 41. Consequently, in the aqueous solution S1 of the first electrode chamber 11 and the Li-containing non-aqueous solution FS of the Li supply chamber 12, reactions occur respectively as described in the first embodiment (see [reference]). Figure 2 The reaction is the same as in the second embodiment. That is, in the aqueous solution S1, O2 is generated near the first electrode 41 by the reaction of formula (1) or formula (5), and H2O in the aqueous solution S1 is generated. + The reaction of formula (6) involves the movement of the Li-containing non-aqueous solution FS through the ion exchange membrane 31 and into the Li supply chamber 12. Furthermore, in the Li-containing non-aqueous solution FS, Li... + The reaction of the following formula (7) moves into the electrolyte membrane 2.

[0149] [Chemical Formula 20]

[0150] In the aqueous solution S2 of the second electrode chamber 14, which is equipped with the second electrode 42C, an interaction occurs with that in the third embodiment ( Figure 8 The same reaction occurs. That is, by applying a voltage (V1+V2), the reaction of equation (4) occurs near the second electrode 42C to generate H2 and OH. -On the other hand, in the Li recovery aqueous solution RS of the Li recovery chamber 13, where the third electrode 43 is disposed, similarly to the second embodiment, by applying voltage V2, OH- in the Li recovery aqueous solution RS near the third electrode 43 is... - The reaction described in equation (1) produces H2O and O2. This reaction is the same as in the second embodiment, but slower than the reaction described in equation (4) near the second electrode 42C (aqueous solution S2). Therefore, in order to maintain charge balance, the OH- in aqueous solution S2 is present in both aqueous solution S2 and RS. - The fluid moves through the bipolar membrane 33 to the Li recovery aqueous solution RS, while the H+ in the Li recovery aqueous solution RS... + Li migrates through the bipolar membrane 33 into the aqueous solution S2. Li also migrates from the electrolyte membrane 2 into the aqueous solution RS for Li recovery. + The reaction of the following formula (3) after it has been moved.

[0151] [Chemical Formula 21]

[0152] Similar to the second embodiment, in this embodiment, a potential gradient is generated in the Li recovery aqueous solution RS by applying voltage V2. The potential on the back side of the electrolyte membrane 2 is maintained at a relatively high level at which O2 is generated. Regardless of the potential difference between the two sides, the electrolyte membrane 2 will not conduct electrons e. - Furthermore, through this potential gradient, the Li between the two sides of electrolyte membrane 2... + The concentration gradient increases. Therefore, it can increase the potential difference (voltage V1) between the two sides of electrolyte membrane 2, causing Li... + It moves at high speed to the aqueous solution RS for Li recovery. The relative magnitudes of voltage V1 and voltage V2 are as described in the second embodiment.

[0153] (Variation example) The lithium recovery apparatus 1C according to the modified example of the first embodiment (see reference) Figure 4 Similarly, the first ion-conducting membrane of the lithium recovery device 1F according to this embodiment can be an anion exchange membrane 32. Furthermore, similar to the lithium recovery device according to the third embodiment, the second ion-conducting membrane of the lithium recovery device 1F can be an anion exchange membrane. Additionally, the lithium recovery device 1E according to the modified example of the third embodiment (see...) Figure 9 Similarly, the lithium recovery device 1F can contain non-aqueous solution RSA for Li recovery in the Li recovery chamber 13.

[0154] Similar to the second embodiment, the lithium recovery apparatus according to the fourth embodiment and its variations can increase the amount of Li recovered per unit time from the non-aqueous solution by increasing the applied voltage, and similarly to the third embodiment, can suppress power consumption.

[0155] [Fifth Implementation] In the lithium recovery apparatus according to the first embodiment, in order to generate O2 at the positive electrode, an ion exchange membrane is used to separate a Li supply chamber for feeding a non-aqueous solution containing Li and a chamber for containing H2. + The first electrode chamber supplies water from the source, but a simpler structure can also be used. The lithium recovery method according to the fifth embodiment of the present invention will be described below.

[0156] (Lithium recovery device) This section describes the lithium recovery apparatus used in the lithium recovery method according to the fifth embodiment of the present invention (hereinafter, the lithium recovery apparatus according to the fifth embodiment). For example... Figure 12 As shown, the lithium recovery apparatus 1G according to the fifth embodiment includes: an electrolyte membrane (lithium-ion conductive electrolyte membrane) 2; a processing tank 7, which is divided by the electrolyte membrane 2 into a chamber (second chamber) 12 and a chamber (first chamber) 13; electrodes 41A and 42B, which are disposed in each of the chambers 12 and 13; and a power supply 5, which is connected between electrodes 41A and 42B with the side of chamber (second chamber) 12, i.e., electrode 41A, as positive. Chamber (second chamber) 12 is a Li supply chamber for containing a non-aqueous solution containing Li FS and also for containing water (H2O). Chamber (first chamber) 13 is a Li recovery chamber for containing an aqueous solution RS for Li recovery. The lithium recovery apparatus 1G may also include water supply devices 81 and 84 for supplying water to chambers 12 and 13, and a stirrer 8 for stirring the non-aqueous solution containing Li FS and water (H2O) in chambers 12 and 13, as needed. Similar to the lithium recovery device 1 according to the first embodiment, the lithium recovery device 1G may also include a heating device, a cooling device, a liquid level sensor, a pH meter, an exhaust unit, etc. The lithium recovery device 1G according to this embodiment has the same... Figure 25 The apparatus 101 shown has the same structure as the one used to recover Li from Li-containing aqueous solutions such as seawater.

[0157] The Li-containing non-aqueous solution FS can be the same non-aqueous solution as in the first and second embodiments, and can be a water-soluble organic solvent (e.g., EC) or a sparingly soluble or insoluble organic solvent (e.g., EMC). Similar to the aqueous solution S1 in the first embodiment, the water contained in the Li supply chamber 12 along with the Li-containing non-aqueous solution FS can be pure water, or any of an acidic, neutral, or alkaline aqueous solution. In the Li supply chamber 12, as long as it contains H... + The total number of valences of the isocations is greater than the amount of Li that is to be moved from the non-aqueous Li-containing solution FS to the aqueous Li recovery solution RS.+ A large quantity of water (H2O) can be contained. On the other hand, in the Li supply chamber 12, when water is in excess relative to the Li-containing non-aqueous solution FS, the Li in contact with the electrolyte membrane 2... + Li relative to Li-containing non-aqueous solutions FS + As the concentration decreases, Li + The migration rate decreases. Specifically, at the start of operation of the lithium recovery unit 1G, it can accommodate the recovery capacity of the non-aqueous solution containing Li and Li. + During operation, the water supply device 81 can replenish the Li supply chamber 12 with the corresponding concentration of water. Similar to the first embodiment, the Li recovery aqueous solution RS is preferably pure water or LiOH aqueous solution at the start of operation of the lithium recovery device 1G.

[0158] The first electrode 41A and the second electrode 42B are electrodes used to apply a voltage between the two sides of the electrolyte membrane 2 to generate a low potential difference on the Li recovery chamber 13 side. Therefore, electrodes 41A and 42B are disposed in each of the chambers 12 and 13 of the processing tank 7. The first electrode 41A and the second electrode 42B are disposed facing each other, either in contact with or separated from the electrolyte membrane 2, preferably parallel to and closer to the electrolyte membrane 2. Furthermore, it is preferable that at least one of the first electrode 41A and the second electrode 42B is separated from the electrolyte membrane 2, and more preferably one is in contact with the electrolyte membrane 2 while the other is separated. Figure 12 In this embodiment, the first electrode 41A is in contact with the electrolyte membrane 2, while the second electrode 42B is separated. The second electrode 42B can have the same structure as in the second embodiment.

[0159] As described above, the first electrode 41A is disposed in contact with the electrolyte membrane 2. This first electrode 41A is preferably sized such that a voltage is applied to a large area of ​​the electrolyte membrane 2. Furthermore, it is preferable to have a porous structure such as a mesh, where the Li-containing non-aqueous solution FS contacts a sufficient area of ​​the surface of the electrolyte membrane 2, or to be continuously replaced. Additionally, similar to the second electrode 42 of the first embodiment, the first electrode 41A can be formed directly on one side of the electrolyte membrane 2, or it can be fixed to the processing tank 7 or the like by a clamp in contact with the electrolyte membrane 2. The first electrode 41A is formed of an electrode material that is stable when a voltage is applied in the Li-containing non-aqueous solution FS and water. Furthermore, similar to the first electrode 41 of the first embodiment, it is formed of a material with electronic conductivity, preferably catalytically active for the reaction of formula (1) or formula (5). It is further preferable that the first electrode 41A is made of a material that is easily processed into the shape described above.

[0160] [Chemical Formula 22]

[0161] In the lithium recovery device 1G, water is supplied to the Li supply chamber 12 by water supply device 81 and to the Li recovery chamber 13 by water supply device 84. During operation, water is replenished by water supply device 81 because the water in the mixed solution FS+H2O in the Li supply chamber 12 decreases due to the reaction of formula (1) or formula (5). Similarly, water is replenished by water supply device 84 because the water in the Li recovery aqueous solution RS decreases due to the reaction of formula (4) during operation.

[0162] The stirrer 8 has a screw and a motor for rotating the screw, and a known stirrer can be used. The stirrer 8, located in the Li supply chamber 12, stirs the Li-containing non-aqueous solution FS and water within the Li supply chamber 12, and circulates the mixture FS+H2O in contact with the electrolyte membrane 2 and the first electrode 41A by continuously replacing it. In particular, when the organic solvent containing the Li-containing non-aqueous solution FS is poorly soluble or insoluble in water, it is preferable that the mixture FS+H2O be continuously stirred during the operation of the lithium recovery device 1G. Alternatively, it can be as described in the sixth embodiment described later (see...). Figure 15 The mixture FS+H2O is circulated within the Li supply chamber 12 and outside the processing tank 7 while being stirred. A stirrer 8, located in the Li recovery chamber 13, continuously stirs the mixture by replacing the aqueous Li recovery solution RS that is in contact with the electrolyte membrane 2 and the second electrode 42B. Alternatively, it can be circulated as in the first embodiment (see...). Figure 1 It has a circulation device 83.

[0163] (Lithium recovery methods) Reference Figure 13 The lithium recovery method according to the fifth embodiment of the present invention will be described below. The lithium recovery method according to this embodiment is performed by the lithium recovery apparatus 1G in the following manner. Furthermore, in Figure 13 In this paper, the agitator 8 and water supply devices 81 and 84 are omitted.

[0164] Similar to the first embodiment, in the lithium recovery apparatus 1G, the power supply 5 applies a positive voltage V1 (+V1) to the first electrode 41A relative to the second electrode 42B. With the application of voltage +V1, the following reaction occurs in the mixture FS+H2O containing a non-aqueous solution of Li and water in the Li supply chamber 12. Here, the reaction is described in the case where the non-aqueous solution of Li is insoluble in water and the mixture FS+H2O separates into an aqueous phase and an organic solvent phase (non-aqueous phase). Similar to the first embodiment (see...),... Figure 2 Similarly, near electrode 41A, OH- in water (H2O) - The reaction shown in equation (1) produces H2O and O2, which allows electrons to be generated. -Released to electrode 41A. Alternatively, water (H2O) reacts with equation (5) to produce H. + And O2, making electrons e - Released to electrode 41A. In the water (H2O) of the mixture, accompanied by OH... - Reduce or H + To maintain charge balance, H₂O from H₂O occurs near the interface with the Li-containing non-aqueous solution FS. + The reaction of equation (6) involves the migration to the non-aqueous Li-containing solution FS. When the water in the Li supply chamber 12 is an aqueous solution containing metal ions, the metal ions sometimes also migrate to the non-aqueous Li-containing solution FS. Additionally, the non-aqueous Li-containing solution FS contains water-soluble anions A. n- In some cases, anion A occurs. n- The reaction of equation (11) moves toward water. Then, in the Li-containing non-aqueous solution FS of the mixture, as H... + Other cations increase or further increase with anion A n- To reduce charge and maintain charge balance, Li in the non-aqueous Li-containing FS occurs near the surface of electrolyte membrane 2. + The reaction of the following formula (7) moves into the electrolyte membrane 2.

[0165] [Chemical Formula 23]

[0166] Furthermore, in the case where the non-aqueous solution containing Li FS is soluble in water and the mixture FS+H2O is a single phase, even if the water in the Li supply chamber 12 is pure water or an alkaline aqueous solution, the reaction of formula (5) will occur near the first electrode 41A. In addition, the reaction of formula (6) and the reaction of formula (11) are omitted, and the reaction of formula (7) occurs.

[0167] On the other hand, in the Li recovery aqueous solution RS in the Li recovery chamber 13, by applying voltage +V1, the reactions of the following formula (4) and the following formula (3) occur, similar to the first embodiment, generating H2 near the second electrode 42B, and Li in the electrolyte membrane 2... + The aqueous solution RS is moved towards Li recovery.

[0168] [Chemical Formula 24]

[0169] Li can be recovered from the aqueous solution RS for Li recovery in the Li recovery chamber 13 and the circulation chamber of the circulation device 83 after operation is completed using the same method as in the first embodiment. Alternatively, Li can be recovered from the mixture of a non-aqueous solution FS containing Li and water in the Li supply chamber 12 and the circulation tank of the circulation device 82.+ Other metal ions M n+ The organic solvents are recovered using their respective known methods.

[0170] In the lithium recovery method described in this embodiment, in order to reuse the Li-containing non-aqueous organic solvent as the Li source, a process of separation from water is required after operation. On the other hand, since an ion exchange membrane is not required, the structure of the lithium recovery device is simplified. Furthermore, Li can be recovered even when it is difficult to obtain an ion exchange membrane resistant to organic solvents based on the Li-containing non-aqueous organic solvent. Additionally, the H+ contained in the water... + Alternatively, other cations moving towards Li-containing non-aqueous solutions (organic solvents) do not require the energy to pass through the ion exchange membrane, thus reducing the corresponding amount of power consumption.

[0171] (Variation example) Similar to the first embodiment, the lithium recovery apparatus according to this embodiment may also contain a non-aqueous solution RSA for Li recovery (see reference 1) in the Li recovery chamber 13. Figure 3 In this case, the second electrode 42B is formed of an electrode material that is stable even when voltage is applied in a non-aqueous solution RSA for Li recovery. Furthermore, compared with the variation of the first embodiment (see...), Figure 3 Similarly, by replacing the second electrode 42B with a second electrode 42A, metallic lithium can be deposited on the surface of the second electrode 42A for recovery (see reference). Figure 3 ).

[0172] Furthermore, in the lithium recovery method involved in this embodiment, as in the second embodiment (see...), Figure 6 In this way, the lithium recovery device has two power supplies, each with an appropriate voltage, thereby increasing the amount of Li recovered per unit time. That is, as... Figure 14As shown, the lithium recovery apparatus (hereinafter, the lithium recovery apparatus according to the modified example of the fifth embodiment) 1H used in the lithium recovery method according to the fifth embodiment of the present invention includes: an electrolyte membrane (lithium-ion conductive electrolyte membrane) 2; a processing tank 7, which is divided into two chambers 12 and 13 by the electrolyte membrane 2; an electrode 41, which is disposed in the Li supply chamber (second chamber) 12; a third electrode 43, which is disposed in contact with the electrolyte membrane 2 in the Li recovery chamber (first chamber) 13; a second electrode 42B, which is disposed separately from the third electrode 43; a first power supply 51, which is connected between the electrodes 41 and 42B with the first electrode 41 as the positive electrode; and a second power supply 52, which is connected in series with the negative electrode of the first power supply 51, and the third electrode 43 is connected to the negative electrode of the first power supply 51. Similar to the embodiment described above, the Li supply chamber 12 contains a non-aqueous solution containing Li FS and water (H2O), and the Li recovery chamber 13 contains an aqueous solution for Li recovery RS. The lithium recovery unit 1H may also include a stirrer 8 and water supply devices 81 and 84 (see reference). Figure 12 The elements of the lithium recovery device 1H involved in this variation example can have the same structure as the elements of the lithium recovery device 1B involved in the second embodiment and the lithium recovery device 1G involved in the fifth embodiment.

[0173] Compared with the second embodiment (see the second embodiment) Figure 6 Similarly, such as Figure 14 As shown, in the lithium recovery method of this modified example implemented by the lithium recovery device 1H, voltage V1 applied by the first power source 51 and voltage V2 applied by the second power source 52 are performed simultaneously. The reaction of the mixture FS+H2O containing Li non-aqueous solution FS and water in the Li supply chamber 12 is the same as described in the embodiment (refer to...). Figure 13 The reaction is the same as in the second embodiment. On the other hand, the reaction of the aqueous solution RS for Li recovery in the Li recovery chamber 13 is the same as in the second embodiment. Furthermore, the relative magnitudes of voltage V1 and voltage V2 are as described in the second embodiment.

[0174] Similar to the second embodiment, the lithium recovery apparatus according to this modification may also contain a non-aqueous solution RSA for Li recovery (see reference 13) in the Li recovery chamber 13. Figure 3 ).

[0175] According to the lithium recovery method described in the fifth embodiment and its variations, a lithium recovery device with a simple structure similar to that of the prior art can be used (see [reference]). Figure 25 In the same manner as in Embodiment 1, Li is recovered from non-aqueous solutions.

[0176] [Sixth Implementation] Alternatively, the lithium recovery apparatus according to the fifth embodiment can be separated from the Li recovery chamber side of the processing tank by an ion exchange membrane, and a second electrode chamber can be provided as in the third embodiment. Hereinafter, the lithium recovery method according to the sixth embodiment of the present invention will be described.

[0177] (Lithium recovery device) like Figure 15 As shown, the lithium recovery apparatus 1J according to the sixth embodiment of the present invention includes: an electrolyte membrane (lithium-ion conductive electrolyte membrane) 2; a bipolar membrane (second ion conductive membrane) 33; a processing tank 7, which is divided into three chambers by the electrolyte membrane 2 and the bipolar membrane 33 in the order of chambers 12, 13, and 14; a first electrode 41A, which is disposed in the chamber (second chamber) 12 at one end of the processing tank 7; a second electrode 42C, which is disposed in the chamber (third chamber) 14 at the other end; and a power supply 5, which is connected between electrodes 41A and 42C with the first electrode 41A as the positive electrode. The chamber (second chamber) 12 at the end of the processing tank 7, which is separated by the electrolyte membrane 2, is a Li supply chamber for containing a non-aqueous solution containing Li (FS) and also for containing water (H2O). The central chamber (first chamber) 13 is a Li recovery chamber for containing an aqueous solution for Li recovery (RS). The end chamber (third chamber) 14, separated by the bipolar membrane 33, is the second electrode chamber, used to contain the aqueous solution S2. The lithium recovery device 1J may also include circulation devices 82 and 83 and a water supply device 84, depending on the requirements. Similar to the lithium recovery device 1 according to the first embodiment, the lithium recovery device 1J may also include a heating device, a cooling device, a liquid level sensor, a pH meter, an exhaust unit, etc. The lithium recovery device 1J according to this embodiment is configured to... Figure 12 The lithium recovery apparatus 1G according to the fifth embodiment shown has an additional bipolar membrane 33, and a second electrode chamber 14 is added to the end of the processing tank 7 on the Li recovery chamber 13 side, and a second electrode 42C is disposed in the second electrode chamber 14.

[0178] The elements of the lithium recovery device 1J according to this embodiment can have the same structure as those of the lithium recovery device 1D according to the third embodiment and the lithium recovery device 1G according to the fifth embodiment. In the lithium recovery device 1J, the circulation device 82 circulates the mixture FS+H2O in the Li supply chamber 12 and outside the processing tank 7 while stirring it, and replenishes it as water is reduced by the reaction of formula (1) or formula (5). Alternatively, as with the lithium recovery device 1G according to the fifth embodiment, the lithium recovery device 1J can have a stirrer 8 and a water supply device 81. In addition, it is preferable that the aqueous solution S2 does not have a high pH value relative to the mixture FS+H2O in the Li supply chamber 12 or the water (aqueous solution) inside it, and it is even more preferable that it has a lower pH value.

[0179] (Lithium recovery methods) Reference Figure 16 The lithium recovery method according to the sixth embodiment of the present invention will be described below. The lithium recovery method according to this embodiment is performed using a lithium recovery apparatus 1J as follows. Furthermore, in Figure 16 In this paper, the circulation devices 82 and 83 and the water supply device 84 are omitted.

[0180] Similar to the first embodiment, in the lithium recovery method according to the sixth embodiment of the present invention, the power supply 5 applies a positive voltage V1 (+V1) to the first electrode 41A relative to the second electrode 42C. The reaction of the mixture FS+H2O containing a non-aqueous solution of Li and water in the Li supply chamber 12 is the same as in the fifth embodiment (see...). Figure 13 The reactions are the same as in the third embodiment (see Figure 14). On the other hand, the reactions in the Li recovery aqueous solution RS in the Li recovery chamber 13 and the aqueous solution S2 in the second electrode chamber 14 are the same as in the third embodiment. Figure 8 )same.

[0181] (Variation example) Similar to the third embodiment, the second ion-conducting membrane of the lithium recovery device according to this embodiment can be an anion-exchange membrane. Furthermore, by using an anion-exchange membrane for the second ion-conducting membrane, the modification of the third embodiment (see [reference]) is similar. Figure 9 Similarly, non-aqueous solution RSA for Li recovery can be contained in Li recovery chamber 13.

[0182] The lithium recovery device according to this embodiment, like that in the fourth embodiment, has two power supplies, each with an appropriate voltage, thereby increasing the amount of Li recovered per unit time. That is, as... Figure 17 As shown, the lithium recovery apparatus 1K according to a modified example of the sixth embodiment of the present invention includes: an electrolyte membrane (lithium-ion conductive electrolyte membrane) 2; a bipolar membrane (second ion conductive membrane) 33; a processing tank 7, which is divided into three chambers by the electrolyte membrane 2 and the bipolar membrane 33 in the order of chambers 12, 13, and 14; a first electrode 41, which is disposed in the Li supply chamber (second chamber) 12; a second electrode 42C, which is disposed in the second electrode chamber (third chamber) 14; a third electrode 43, which is disposed in contact with the electrolyte membrane 2 in the Li recovery chamber (first chamber) 13; a first power supply 51, which is connected between electrodes 41 and 42C with the first electrode 41 as the positive electrode; and a second power supply 52, which is connected in series with the negative electrode of the first power supply 51, and the third electrode 43 is connected to the negative electrode of the first power supply 51. Similar to the embodiment described above, the Li supply chamber 12 contains a non-aqueous solution of Li (FS) and water (H2O), the Li recovery chamber 13 contains an aqueous solution of Li for recovery (RS), and the second electrode chamber 14 contains an aqueous solution (S2). The lithium recovery device 1K may also include circulation devices 82 and 83 and a water supply device 84, as needed. (Ref.) Figure 15The elements of the lithium recovery device 1K involved in this modification can be compared with the lithium recovery device 1F involved in the fourth embodiment and the lithium recovery device 1J involved in the sixth embodiment (see reference). Figure 10 , Figure 15 The elements of ) have the same structure.

[0183] Compared with the second embodiment (see the second embodiment) Figure 6 Similarly, such as Figure 17 As shown, in the lithium recovery method of this modified example implemented by the lithium recovery device 1K, voltage V1 is applied by the first power source 51 and voltage V2 is applied by the second power source 52 simultaneously. The reaction of the mixture FS+H2O containing Li non-aqueous solution FS and water in the Li supply chamber 12 is the same as in the fifth embodiment (see...). Figure 13 The reactions are the same as in the fourth embodiment (see Figure 4). On the other hand, the reactions in the Li recovery aqueous solution RS in the Li recovery chamber 13 and the aqueous solution S2 in the second electrode chamber 14 are the same as in the fourth embodiment. Figure 11 The same applies. Furthermore, the relative magnitudes of voltage V1 and voltage V2 are as described in the second embodiment.

[0184] Similar to the lithium recovery apparatus described in the above embodiments, the second ion-conducting membrane of the lithium recovery apparatus 1K in this modified example can be an anion exchange membrane. Furthermore, by using an anion exchange membrane on the second ion-conducting membrane, non-aqueous solution RSA for Li recovery can be contained in the Li recovery chamber 13.

[0185] Similar to the third embodiment, the lithium recovery method according to the sixth embodiment and its variations can recover Li from non-aqueous solutions, can easily control the electrolysis voltage to suppress power consumption, and can be a lithium recovery device with a relatively simple structure.

[0186] [Seventh Implementation] In the lithium recovery apparatus according to the third embodiment, electrodes are not arranged in the Li supply chamber and the Li recovery chamber. Instead, a first electrode chamber and a second electrode chamber are provided on both sides of these two chambers, separated by ion exchange membranes. Li is then transferred between the first electrode chamber and the Li supply chamber, and between the Li recovery chamber and the second electrode chamber. + Other ions move through the ion-conducting membrane, thereby allowing Li to... + Through the electrolyte membrane. Thus, by utilizing the combination of multiple Li supply chambers and Li recovery chambers, Li is not conductive. + The ion-conducting membranes are separated and connected, and a first electrode and a second electrode are arranged in the chambers at both ends, thereby enabling a large amount of Li source (containing non-aqueous solutions of Li) to be processed by a single power source, increasing the Li recovery rate. The following describes a multi-chamber lithium recovery apparatus according to embodiments of the present invention.

[0187] (Multi-chamber lithium recovery unit) like Figure 18 As shown, the multi-chamber lithium recovery device 10 according to an embodiment of the present invention includes: two electrolyte membranes (lithium-ion conductive electrolyte membranes) 2; an ion exchange membrane (first ion conductive membrane) 31; two bipolar membranes (second ion conductive membranes) 33; a processing tank 7A, which is divided into six chambers by the electrolyte membranes 2 and the ion conductive membranes 31 and 33; a power supply 5; a first electrode 41 connected to the positive terminal of the power supply 5; and a second electrode 42C connected to the negative terminal. The electrolyte membranes 2 and the ion conductive membranes 31 and 33 are arranged alternately, and the ion exchange membrane 31 is arranged at one end. Therefore, the membranes 31, 2, 33, 2, 33 are arranged sequentially from one end, and the processing tank 7A is divided into chambers 11, 12a, 13a, 12b, 13b, and 14. The first electrode 41 is disposed in the first electrode chamber 11 at one end of the processing tank 7A, which is separated by the ion exchange membranes 31, and the second electrode 42C is disposed in the second electrode chamber 14 at the other end. Water (aqueous solutions S1 and S2) is contained in chambers 11 and 14, respectively. Chambers 12a and 12b are Li supply chambers for containing non-aqueous solutions containing Li (FS). Chambers 13a and 13b are Li recovery chambers for containing aqueous solutions for Li recovery (RS). The multi-chamber lithium recovery device 10 may also include water supply devices 81 and 84 and circulation devices 82A and 83A as needed. The multi-chamber lithium recovery device 10 of this embodiment is connected to two lithium recovery devices 1D of the third embodiment (see reference). Figure 7 In this configuration, the second electrode chamber 14 of one of the adjacent lithium recovery units 1D is removed, and the Li recovery chamber 13 (13a) of that unit is integrated with the first electrode chamber 11 of the other unit. Figure 18 In the multi-chamber lithium recovery device 10, there are two electrolyte membranes 2 and two sets of Li supply chambers and Li recovery chambers, but the number of them is any number of two or more.

[0188] The processing tank 7A has dimensions corresponding to the number of compartments, but otherwise it can have the same structure as the processing tank 7 of the lithium recovery unit 1.

[0189] Similar to the circulation device 82 of the lithium recovery device 1, the circulation device 82A is a device that continuously replaces the Li-containing non-aqueous solution FS in each of the Li supply chambers 12a and 12b during operation, and also continuously replaces the Li-containing non-aqueous solution FS in contact with the electrolyte membrane 2. The circulation device 82A can be configured with the same structure as the circulation device 82, except that it has circulation paths such as hoses communicating with the Li supply chambers 12a and 12b respectively. Furthermore, while one circulation device 82A can circulate all the Li-containing non-aqueous solution FS in the Li supply chambers 12a and 12b together, separate circulation devices 82 can be installed for each of the Li supply chambers 12a and 12b to circulate the Li-containing non-aqueous solution FS in an independent system.

[0190] Similar to the circulation device 83 of the lithium recovery device 1, the circulation device 83A is a device that continuously replaces the Li recovery aqueous solution RS in each of the Li recovery chambers 13a and 13b during operation, and also continuously replaces the Li recovery aqueous solution RS in contact with the electrolyte membrane 2. The circulation device 83A can be configured with the same structure as the circulation device 83, except that it has circulation paths such as hoses communicating with the Li recovery chambers 13a and 13b respectively. Alternatively, the circulation device 83 can be installed separately for the Li recovery chambers 13a and 13b, forming an independent system for circulating the Li recovery aqueous solution RS.

[0191] The other elements of the multi-chamber lithium recovery device 10 involved in this embodiment can have the same structure as the elements of the lithium recovery device 1 involved in the first embodiment and the lithium recovery device 1D involved in the third embodiment.

[0192] (Lithium recovery methods) Reference Figure 19 The lithium recovery method according to the seventh embodiment of the present invention will be described below. The lithium recovery method according to this embodiment is performed using a multi-chamber lithium recovery apparatus 10 as follows. Furthermore, in Figure 19 In this drawing, water supply devices 81 and 84 and circulation devices 82A and 83A are omitted. Furthermore, for ease of identification, electrolyte membrane 2 is labeled with different reference numerals than electrolyte membranes 21 and 22. Electrolyte membrane 21 separates the Li supply chamber 12a and the Li recovery chamber 13a, and electrolyte membrane 22 separates the Li supply chamber 12b and the Li recovery chamber 13b. Additionally, the non-aqueous Li-containing aqueous solution FS in each of the Li supply chambers 12a and 12b is appropriately referred to as non-aqueous Li-containing aqueous solution FSa and FSb. Similarly, the aqueous Li recovery solution RS in each of the Li recovery chambers 13a and 13b is appropriately referred to as aqueous Li recovery solution RSa and RSb (the same applies in the variations described later).

[0193] Compared with the first embodiment (see the first embodiment) Figure 2 Similarly, in this embodiment, the power supply 5 applies a positive voltage V1 (+V1) to the first electrode 41 relative to the second electrode 42C. The reactions in the aqueous solution S1 of the first electrode chamber 11 and the Li-containing non-aqueous solution FSa of the Li supply chamber 12a, respectively, caused by the application of voltage +V1, are the same as the reactions in the aqueous solution S1 and the Li-containing non-aqueous solution FS in the first embodiment. That is, in the aqueous solution S1, O2 is generated near the first electrode 41 by the reaction of formula (1) or formula (5), and H2O in the aqueous solution S1 is generated. + The reaction described in equation (6) involves the movement of Li-containing non-aqueous solution FSa through ion exchange membrane 31 into Li supply chamber 12a. Furthermore, in the Li-containing non-aqueous solution FSa, Li... + The reaction of the following formula (7) moves into the electrolyte membrane 2.

[0194] [Chemical Formula 25]

[0195] Furthermore, by applying voltage +V1, the following reaction occurs in the Li recovery aqueous solution RSa of Li recovery chamber 13a: H₂O from the water (H₂O) in the Li recovery aqueous solution RSa... + The Li-containing non-aqueous solution FSb migrates through the bipolar membrane 33 into the Li supply chamber 12b. Accompanied by H... + To maintain charge balance, a reduction in Li content occurs near the Li recovery chamber 13a side (back side) of the electrolyte membrane 21. + The reaction of equation (3) is transferred to the Li recovery aqueous solution RSa. In the Li recovery aqueous solution RSa, an electric field is further generated from the electrolyte membrane 21 side to the bipolar membrane 33 side by applying a voltage +V1, and Li... + Due to electrostatic attraction, the electrolyte membrane 21 moves away from the vicinity of its back surface. On the other hand, in the Li-containing non-aqueous solution FSb of the Li supply chamber 12b, by applying a voltage +V1, an electric field is generated from the bipolar membrane 33 side towards the electrolyte membrane 22 side, and Li, as a cation in the Li-containing non-aqueous solution FSb... + M n+ They are attracted to the surface of the electrolyte membrane 22 due to electrostatic attraction. Additionally, accompanied by H... + To maintain charge balance, Li in the non-aqueous Li-containing FSb in the electrolyte membrane 22 undergoes an increase in charge near the surface of the membrane 22. +The reaction of formula (7) moves into the electrolyte membrane 22. That is, the same reaction as the aqueous solution S1 and the aqueous solution FSa occur in the Li recovery aqueous solution RSa and the Li-containing aqueous solution FSb, respectively, and the Li recovery aqueous solution RS (RSa) in the Li recovery chamber 13a has the same function as the aqueous solution S1.

[0196] [Chemical Formula 26]

[0197] On the other hand, the reactions in the aqueous solution S2 in the second electrode chamber 14 and the aqueous solution RSb for Li recovery in the Li recovery chamber 13b are the same as in the third embodiment (see...). Figure 8 The reactions in the aqueous solution S2 and the aqueous solution RS for Li recovery are the same. That is, in the aqueous solution S2, the reaction of equation (4) occurs near the second electrode 42C to generate OH. - Along with this, OH - The Li recovery aqueous solution RSb moves through the bipolar membrane 33 into the Li recovery chamber 13b, while the H+ in the Li recovery aqueous solution RSb... + It migrates through the bipolar membrane 33 into the aqueous solution S2. Furthermore, in the Li recovery aqueous solution RSb, H... + The reduction and OH - The increase of Li in electrolyte membrane 22 leads to the formation of Li + The reaction of the following equation (3) is transferred. In the aqueous solution RSb for Li recovery, an electric field is generated from the electrolyte membrane 22 side to the bipolar membrane 33 side by applying a voltage +V1, and Li + Due to electrostatic attraction, it moves away from the vicinity of the back side of the electrolyte membrane 22.

[0198] [Chemical Formula 27]

[0199] (Variation example) The lithium recovery apparatus 1C according to the modified example of the first embodiment (see reference) Figure 4 Similarly, the multi-chamber lithium recovery device involved in this embodiment contains anions A in the non-aqueous solution of Li FS. n- In cases involving water-soluble anions, anion exchange membranes 32 and 34 can be used for the first and second ion-conducting membranes. For example... Figure 20 As shown, in the multi-chamber lithium recovery device 10A involved in this modified example, the anion A contained in the Li non-aqueous solution FS n-It will move to the Li recovery aqueous solution RS. Furthermore, for example, the first ion-conducting membrane can be an anion exchange membrane 32, and the second ion-conducting membrane can be a bipolar membrane 33 or a proton-conducting membrane. Moreover, regarding the second ion-conducting membrane, the membrane disposed between the electrolyte membranes 2 can be of a different type than the membrane separating the second electrode chamber 14. In particular, similar to the described embodiment, by using a bipolar membrane 33 or a proton-conducting membrane for the second ion-conducting membrane disposed between the electrolyte membranes 2, it is possible to prevent anion A from moving to the Li recovery aqueous solution RS. n- The aqueous solution RS used for Li recovery was mixed in.

[0200] like Figure 21 As shown, the multi-chamber lithium recovery apparatus according to this embodiment may omit the second electrode chamber 14, and instead place the second electrode 42C in the Li recovery chamber 13b, which is located at the end opposite to the first electrode chamber 11. In this modified example, the multi-chamber lithium recovery apparatus 10B, in the Li recovery aqueous solution RSb of the Li recovery chamber 13b, reacts with the first embodiment (see...). Figure 2 The Li recovery is carried out using the same reaction as RS in aqueous solution.

[0201] The multi-chamber lithium recovery device involved in this embodiment is similar to the lithium recovery device 1B involved in the second embodiment (see reference). Figure 5 In this way, having two power supplies and setting their respective voltages to appropriate values ​​allows for an increase in the amount of Li recovered per unit time. For example... Figure 22 As shown, in the multi-chamber lithium recovery device 10C of this modified example, as in the lithium recovery device 1F of the fourth embodiment (see...), Figure 10 In this configuration, a third electrode 43 is provided in the Li recovery chamber 13b adjacent to the second electrode chamber 14, which is in contact with the electrolyte membrane 22. Alternatively, as in the multi-chamber lithium recovery apparatus 10B of the modified example described above, in a structure without the second electrode chamber 14, as in the lithium recovery apparatus 1B of the second embodiment, the second electrode 42C is separately disposed in the Li recovery chamber 13b from the electrolyte membrane 22 and the third electrode 43.

[0202] Similar to the lithium recovery apparatus according to the first embodiment, the multi-chamber lithium recovery apparatus according to this embodiment and its variations is capable of recovering Li from non-aqueous solutions and suppressing power consumption per unit of Li recovered.

[0203] Example

[0204] The foregoing has described a method for implementing the lithium recovery apparatus and method of the present invention. The following describes embodiments that confirm the effectiveness of the present invention. Furthermore, the present invention is not limited to these embodiments and methods; various modifications and alterations made based on these descriptions are naturally included within the scope of the present invention.

[0205] [Experiment 1] against Figure 1 The lithium recovery apparatus and lithium recovery method according to the first embodiment of the present invention shown measure the amount of lithium moving per unit time under voltage application.

[0206] (Construction of a lithium recovery device) The lithium recovery device according to Embodiment 1 of the present invention uses a plate-shaped La with a thickness of 0.5 mm. 0.57 Li 0.29 TiO3 (lithium-ion conductive ceramic LLTO, manufactured by Toho Titanium Co., Ltd.) was used as the electrolyte membrane, and a hydrolysis bipolar membrane (NEOSEPTA, manufactured by ASTOM Co., Ltd.) was used as the ion-conducting membrane. Both the electrolyte membrane and the ion-conducting membrane were 50mm in height and 50mm in depth. In a glass processing tank, the bipolar membrane and electrolyte membrane were installed parallel to each other with a 70mm gap, thus dividing the tank into three chambers in one direction. The first electrode chamber (…) was located at the end separated by the ion-conducting membrane… Figure 1 Within the attached figure (reference numeral 11), a 40mm × 30mm Pt mesh electrode is arranged facing the ion-conducting membrane. Figure 1 (Ref. 41 in the attached figure). Additionally, in the Li recovery chamber at the end separated by the electrolyte membrane (…). Figure 1 Within reference numeral 13, a 40mm × 30mm Ni mesh electrode is arranged facing the electrolyte membrane at a distance of 15mm. Figure 1 (See attached figure 42). The distance between the two electrodes is set to 100 mm. A power supply is then connected between the two electrodes, with the first electrode chamber side as the positive terminal, to function as a lithium recovery device. A galvanometer is inserted between the positive terminal of the power supply and the Pt mesh electrode.

[0207] A 1 mol / L non-aqueous solution of lithium perchlorate (LiClO4) was prepared as a Li source (the volume ratio of EC to DMC in the solvent was 1:1). Additionally, as a H... + A 0.1 mol / L lithium hydroxide (LiOH) aqueous solution was prepared using a supply source and an aqueous solution for Li recovery. 150 ml of the non-aqueous solution containing Li was added to the Li supply chamber, which is separated by an ion-conducting membrane and an electrolyte membrane of the lithium recovery device. Additionally, 130 ml of the LiOH aqueous solution was added to both the first electrode chamber and the Li recovery chamber, respectively, with the electrodes completely immersed.

[0208] As a comparative example, the lithium recovery apparatus comprises an electrolyte membrane installed in a glass processing tank, dividing it into two chambers: a Li supply chamber and a Li recovery chamber. A Pt mesh electrode is disposed in the Li supply chamber, and a Ni mesh electrode is disposed in the Li recovery chamber. A power supply and ammeter are connected in the same manner as in the embodiment. The distance between the two electrodes is set to 7 mm. Furthermore, the same electrolyte membrane and electrodes as in Embodiment 1 are used. The same non-aqueous solution of LiClO4 and the same aqueous solution of LiOH as in Embodiment 1 are added to the Li supply chamber and the Li recovery chamber.

[0209] (Lithium recovery experiment) A 2V DC voltage is continuously applied from the power supply, and the current value shift is measured by an ammeter. Regarding Example 1 and the comparative example, in... Figure 23 The figure shows the current value and the conversion of that current value into a shifted Li. + The shift in the amount of movement per unit time. Furthermore, Li + The amount of movement per unit time was calculated by current × time × atomic weight of Li / Faraday constant. The atomic weight of Li is 6.941 g / mol, and the Faraday constant is 96485 C / mol.

[0210] like Figure 23 As shown, in Example 1, due to the sufficiently stable current flow, it can be inferred that the Li-containing non-aqueous solution was purified by electrodialysis. + Water (LiOH aqueous solution) moves into the Li recovery chamber. In contrast, in the comparative example, the current is as small as about 1 / 20th of that in the embodiment, and the Li... + It hardly moves.

[0211] In summary, it can be confirmed that in the lithium recovery apparatus and lithium recovery method according to the first embodiment of the present invention, Li + When dissolved in an organic solvent along with other cations to form a non-aqueous solution, it can be used as a Li source to stably recover Li without decomposing the organic solvent.

[0212] [Experiment 2] against Figure 12 The lithium recovery method according to the fifth embodiment of the present invention shown is similar to that in Example 1, measuring the amount of lithium moving per unit time under applied voltage.

[0213] In the lithium recovery method according to Example 2 of the present invention, the lithium recovery apparatus according to the comparative example of Experiment 1 was used. A 1 mol / L LiPF6 ethanol solution was prepared as the Li source. Additionally, as H... + A 1 mol / L sodium hydroxide (NaOH) aqueous solution was prepared using a source. In the Li supply chamber ( Figure 12In the attached figure (reference numeral 12), 60 ml of LiPF6 ethanol solution and 70 ml of NaOH aqueous solution were added. Meanwhile, in the Li recovery chamber (… Figure 12 In the figure (reference numeral 13), a 0.1 mol / L LiOH aqueous solution was added in the same manner as in Example 1.

[0214] A 2V DC voltage is continuously applied from the power supply, and the current value is measured by an ammeter. Figure 23 The figure shows the current value and the conversion of that current value into a shifted Li. + The amount of movement per unit of time.

[0215] like Figure 23 As shown, in Example 2 of the present invention, since the current flow is approximately 5 times that of the comparative example in Experiment 1, it can be inferred, similarly to Example 1, that the Li-containing non-aqueous solution can be electrodialyzed. + The water (LiOH aqueous solution) moves into the Li recovery chamber.

[0216] Thus, as in the first embodiment, it can be confirmed that in the lithium recovery method according to the third embodiment of the present invention, Li... + A non-aqueous solution formed by dissolving other cations in an organic solvent can be used as a Li source, enabling stable Li recovery without decomposing the organic solvent. Furthermore, a lithium recovery device with the same simple structure as existing technologies (comparative examples) can be used.

[0217] [Experiment 3] against Figure 5 The lithium recovery apparatus and lithium recovery method according to the second embodiment of the present invention shown herein, in the same manner as in Embodiment 1, measure the amount of lithium moving per unit time under applied voltage.

[0218] (Construction of a lithium recovery device) The lithium recovery device according to Embodiment 3 of the present invention is different from the lithium recovery device according to Embodiment 1 (see reference). Figure 1 Using the power supply as the first power source, its negative electrode is connected to the Ni mesh electrode ( Figure 5 A second power source is inserted between the reference numeral 42B and the first power source, and a new Pt mesh electrode is connected to the negative terminal of the first power source. Figure 5 (Ref. 43) In the Li recovery chamber, it is configured in contact with the electrolyte membrane. The distance between the two electrodes in the Li recovery chamber is set to 55 mm. Similar to Example 1, a non-aqueous solution of LiClO4 is introduced into the Li supply chamber, and an aqueous solution of LiOH is introduced into the first electrode chamber and the Li recovery chamber, respectively.

[0219] (Lithium recovery experiment) A 2V DC voltage was continuously applied from power source 1, and a 5V DC voltage was continuously applied from power source 2. The current values ​​were measured using an ammeter. Figure 24 The figure shows the current value and the conversion of that current value into a shifted Li. + The amount of movement per unit of time.

[0220] like Figure 24 As shown, in the lithium recovery device according to Embodiment 3 of the present invention, similarly to Embodiment 1, due to the sufficiently stable current flow, it can be inferred that Li containing non-aqueous solutions of Li is recovered through electrodialysis. + Water (LiOH aqueous solution) moves into the Li recovery chamber. Furthermore, it can be inferred that approximately three times the amount of Li in Example 1 moves per unit time. + This allows for faster recovery. Furthermore, the current value gradually increases over time. This is presumably due to the temperature rise of the electrolyte membrane.

[0221] Thus, similarly to the first embodiment, it can be confirmed that in the lithium recovery apparatus and lithium recovery method according to the second embodiment of the present invention, Li... + Using a non-aqueous solution formed by dissolving other cations in an organic solvent as a Li source, Li can be stably recovered without decomposing the organic solvent. Furthermore, by setting two electrodes in the Li recovery chamber, similar to the apparatus for recovering Li contained in aqueous solutions (see Patent Document 3), it has been confirmed that the recovery rate can be increased.

[0222] [Experiment 4] against Figure 3 The lithium recovery apparatus and lithium recovery method according to the modified example of the first embodiment of the present invention shown were used to observe the movement of lithium.

[0223] The lithium recovery apparatus described in Example 1 of Experiment 1 was used. A 1 mol / L non-aqueous solution of LiPF6 (with a volume ratio of EC to DMC of 1:1 in the solvent) was prepared as both the Li source and the non-aqueous solution for Li recovery and was added to the Li supply chamber and the Li recovery chamber, respectively. Meanwhile, a 0.1 mol / L aqueous solution of LiOH was added to the first electrode chamber, similar to that in Example 1.

[0224] A 10V DC voltage was continuously applied from the power supply, setting the potential of the negative electrode to -5V. After 24 hours, silvery metallic lithium was visually confirmed to have deposited on the surface of the Ni mesh electrode in the Li recovery chamber from the outside of the processing tank. Thus, in the lithium recovery apparatus and lithium recovery method according to the modified example of the first embodiment of the present invention, it was confirmed that metallic Li could be recovered in the Li recovery chamber.

[0225] [Explanation of reference numerals in the attached figures]

[0226] 10, 10A, 10B, 10C: Multi-chamber lithium recovery unit; 1, 1A-1H, 1J, 1K: Lithium recovery unit; 11: First electrode chamber (third chamber); 12: Li supply chamber (second chamber); 13: Li recovery chamber (first chamber); 14: Second electrode chamber (fourth chamber); 2: Electrolyte membrane (lithium-ion conductive electrolyte membrane); 31, 32: Ion exchange membrane (first ion conductive membrane); 33: Bipolar membrane (second ion conductive membrane); 34: Anion exchange membrane (second... (Ion-conducting membrane); 41, 41A: First electrode; 42, 42A, 42B: Second electrode; 43: Third electrode; 5, 5B: Power supply; 51: First power supply; 52: Second power supply; 7, 7A: Processing tank; 81, 84: Water supply device; 82, 82A: Circulation device; 83, 83A: Circulation device; FS: Li-containing non-aqueous solution; RS: Li recovery aqueous solution (water); RSA: Li recovery non-aqueous solution (organic solvent); S1, S2: Aqueous solution (water).

Claims

1. A lithium recovery device comprising a processing tank, a lithium-ion conductive electrolyte membrane, a first ion-conducting membrane, a first electrode, a second electrode, and a power supply, wherein, The processing tank is divided into three chambers in the order of chamber 1, chamber 2, and chamber 3. The lithium-ion conductive electrolyte membrane divides the processing tank into the first chamber and the second chamber; The first ion-conducting membrane divides the processing tank into the second chamber and the third chamber; The first electrode is disposed in the third chamber; The second electrode is disposed in the chamber at the end of the processing tank opposite to the third chamber that is separated from it; The positive terminal of the power supply is connected to the first electrode, and the negative terminal is connected to the second electrode. The method of causing lithium ions to move from a lithium-ion-containing non-aqueous solution contained in the second chamber to water or an organic solvent contained in the first chamber is characterized in that... The first ion-conducting membrane conducts at least one cation other than lithium ions, or at least one water-soluble anion contained in the non-aqueous solution. Water is contained in the third chamber.

2. The lithium recovery device according to claim 1, characterized in that, It also has a second ion-conducting membrane that divides the processing tank into the first and fourth chambers and does not conduct lithium ions. The second electrode is disposed in the fourth chamber. Water is contained in the fourth chamber.

3. A lithium recovery device comprising a processing tank, a lithium-ion conductive electrolyte membrane, a second ion-conducting membrane, a first electrode, a second electrode, and a power supply, wherein, The processing tank is divided into three chambers in the order of chamber 2, chamber 1, and chamber 3. The lithium-ion conductive electrolyte membrane divides the processing tank into the first chamber and the second chamber; The second ion-conducting membrane divides the processing tank into the first chamber and the third chamber, and does not conduct lithium ions; The first electrode is disposed in the second chamber; The second electrode is disposed in the third chamber; The positive terminal of the power supply is connected to the first electrode, and the negative terminal is connected to the second electrode. The method of causing lithium ions to move from a lithium-ion-containing non-aqueous solution contained in the second chamber to water or an organic solvent contained in the first chamber is characterized in that... Water is contained in the third chamber. Water is further contained in the second chamber.

4. The lithium recovery device according to claim 2 or 3, characterized in that, The organic solvent is contained in the first chamber. An aqueous solution containing anions soluble in the organic solvent is contained in the chamber of the processing tank where the second electrode is located. The second ion-conducting membrane conducts the anions.

5. The lithium recovery device according to claim 1, characterized in that, The organic solvent is contained in the first chamber. The power source applies a voltage that makes the potential of the second electrode below the lithium-ion reduction potential.

6. The lithium recovery apparatus according to any one of claims 1 to 4, characterized in that, The power supply is composed of a first power supply and a second power supply connected in series from the positive side. It also has a third electrode, which is connected to the negative terminal of the first power source, separate from the second electrode, and in contact with or facing the surface of the first chamber side of the lithium-ion conductive electrolyte membrane. The first chamber contains water or an organic solvent containing dissolved anions.

7. A lithium recovery method, comprising, in a processing tank divided into a first chamber and a second chamber by a lithium-ion conductive electrolyte membrane, causing lithium ions contained in a non-aqueous solution in the second chamber to move towards water or an organic solvent contained in the first chamber, characterized in that, The processing tank is further divided into a second chamber and a third chamber by a first ion-conducting membrane. The first ion-conducting membrane conducts at least one cation other than lithium ions, or at least one water-soluble anion contained in the non-aqueous solution. Water is contained in the third chamber. A voltage is applied between the first electrode and the second electrode by a power supply connected with the first electrode as positive. The first electrode is located in the third chamber, and the second electrode is located in the chamber at the end of the processing tank opposite to the third chamber, which is separated from it.

8. A lithium recovery method, comprising, in a processing tank divided into a first chamber and a second chamber by a lithium-ion conductive electrolyte membrane, causing lithium ions contained in a non-aqueous solution in the second chamber to move towards water or an organic solvent contained in the first chamber, characterized in that, Water is further contained in the second chamber. A voltage is applied between the first electrode and the second electrode by a power supply connected with the first electrode as positive. The first electrode is disposed in the second chamber, and the second electrode is disposed in the chamber at the end of the processing tank opposite to the second chamber which is separated from it.

9. The lithium recovery method according to claim 7 or 8, characterized in that, The processing tank is further divided into the first chamber and the fourth chamber by a second ion-conducting membrane that does not conduct lithium ions. The second electrode is disposed in the fourth chamber. Water is contained in the fourth chamber.

10. The lithium recovery method according to claim 9, characterized in that, The organic solvent is contained in the first chamber. The processing tank, in the chamber where the second electrode is located, contains an aqueous solution containing anions dissolved in the organic solvent. The second ion-conducting membrane conducts the anions.

11. The lithium recovery method according to claim 7 or 8, characterized in that, The organic solvent is contained in the first chamber. The power source applies a voltage that makes the potential of the second electrode below the lithium-ion reduction potential.

12. The lithium recovery method according to any one of claims 7 to 10, characterized in that, The first chamber contains water or an organic solvent containing dissolved anions. The power supply is composed of a first power supply and a second power supply connected in series from the positive side. A third electrode is connected to the negative terminal of the first power source. The third electrode is separate from the second electrode and is in contact with or facing the surface of the first chamber side of the lithium-ion conductive electrolyte membrane.

13. A multi-chamber lithium recovery device, characterized in that, It comprises a lithium-ion conductive electrolyte membrane, a first ion-conducting membrane, a second ion-conducting membrane, a processing tank, a first electrode, a second electrode, and a power supply, wherein... The lithium-ion conductive electrolyte membrane has two or more components; The first ion-conducting membrane is disposed at one end of the first disposed lithium-ion conductive electrolyte membrane starting from one end. The second ion-conducting membrane is disposed between the lithium-ion conductive electrolyte membranes and does not conduct lithium ions; The processing tank is divided into 5 or more chambers by the first ion-conducting membrane, the lithium-ion conductive electrolyte membrane, and the second ion-conducting membrane; The first electrode is disposed in the chamber at one end of the processing tank, which is divided into sections. The second electrode is located in the room at the other end; The positive terminal of the power supply is connected to the first electrode, and the negative terminal is connected to the second electrode. Water is contained in the chamber at one end of the processing tank, which is divided into sections. In two adjacent chambers separated by the lithium-ion conductive electrolyte membrane, lithium ions are moved from a non-aqueous solution containing lithium ions contained at one end to water contained at the other end.

14. The multi-chamber lithium recovery device according to claim 13, characterized in that, It also includes a second ion-conducting membrane, which separates the processing tank between the first configured lithium-ion conductive electrolyte membrane and the second electrode from the other end side. Water is contained in the chamber at the other end of the treatment tank, which is separated by the second ion-conducting membrane.

15. The multi-chamber lithium recovery device according to claim 13 or 14, characterized in that, The power supply is composed of a first power supply and a second power supply connected in series from the positive side. It also has a third electrode, which is connected to the negative terminal of the first power source, separated from the second electrode, and is in contact with or facing the surface of the first configured lithium-ion conductive electrolyte membrane from the other end side.

16. A lithium recovery method, comprising, in a processing tank divided into five or more chambers by alternating ion-conducting membranes and lithium-ion conductive electrolyte membranes arranged from one end, a method for moving lithium ions from a non-aqueous solution containing lithium ions contained in one of two adjacent chambers separated by the lithium-ion conductive electrolyte membranes to water contained in the other chamber, characterized in that, The ion-conducting membrane disposed between the lithium-ion conductive electrolyte membranes does not conduct lithium ions. Water is contained in the chamber at one end of the processing tank, which is divided into sections. A voltage is applied between a first electrode located in a chamber at one end of the partitioned processing tank and a second electrode located in a chamber at the other end, by a power supply connected with the first electrode as the positive electrode. This causes lithium ions to move from the non-aqueous solution containing lithium ions contained at one end of the two adjacent chambers to the water contained at the other end.

17. The lithium recovery method according to claim 16, characterized in that, The processing tank is separated by a non-lithium-conducting ion-conducting membrane disposed between the first lithium-ion conductive electrolyte membrane disposed from the other end side and the second electrode. Water is contained in a chamber at the other end of the treatment tank, which is separated by the ion-conducting membrane.

18. The lithium recovery method according to claim 16 or 17, characterized in that, The power supply is composed of a first power supply and a second power supply connected in series from the positive side. A third electrode is connected to the negative terminal of the first power source. The third electrode is separate from the second electrode and is in contact with or facing the surface of the first configured lithium-ion conductive electrolyte membrane from the other end side.

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