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

Abstract

In a lithium recovery device 1, a treatment tank 7 is partitioned into three chambers in the order of chambers 11, 12, 13 by means of an ion conductive film 31 and a lithium ion conductive electrolyte film 2. A power supply 5 is connected between electrodes 41, 42 respectively provided inside the chambers 11, 13 located at both ends, with a first electrode chamber 11 side as a positive side. Water S1 is accommodated in the first electrode chamber 11, a non-aqueous solution FS having Li is accommodated in the Li supply chamber 12, and an aqueous solution RS for Li recovery is accommodated in the Li recovery chamber 13. When a voltage is applied by the power supply 5, H+ passes through the ion conductive film 31 from the water S1 and moves to the Li-containing non-aqueous solution FS. In the Li-containing non-aqueous solution FS supplied with H+, in order to keep charge balance, Li+ moves into the lithium ion conductive electrolyte film 2, and Li+ in the lithium ion conductive electrolyte film 2 moves to the aqueous solution RS for Li recovery.

Description

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

[0001] The present invention relates to a lithium recovery device and a lithium recovery method for selectively recovering lithium ions from a non-aqueous solution.

[0002] Lithium (Li) is a resource in high demand as a raw material for lithium-ion secondary batteries and fuel for nuclear fusion reactors, and a stable and inexpensive extraction method is required. + Furthermore, because the positive electrodes of lithium-ion secondary batteries mainly contain Li as lithium cobalt oxide (LiCoO2) or the like, there are expectations for an inexpensive recovery technique from batteries (waste batteries) that have been discarded due to reasons such as the end of their life. While adsorption methods have traditionally been used to recover Li from seawater, electrodialysis using an electrolyte membrane with lithium ion conductivity has been developed as a more selective method (see, for example, Patent Documents 1 to 3 and Non-Patent Document 1).

[0003] An example of the Li recovery method using electrodialysis described in Patent Document 1 and the like will be described with reference to Fig. 25. The lithium recovery device 101 is configured by dividing a treatment tank 107 into a Li supply chamber 112 and a Li recovery chamber 113 by a lithium ion conductive electrolyte membrane (hereinafter referred to as electrolyte membrane) 2, and connecting a power supply 105 between an electrode 141 in the Li supply chamber 112 and an electrode 142 in the Li recovery chamber 113 with the electrode 141 serving as the positive electrode. A Li-containing aqueous solution SW such as seawater is introduced into the Li supply chamber 112 as a Li source, and a Li recovery aqueous solution RS such as pure water is introduced into the Li recovery chamber 113. The Li-containing aqueous solution SW contains lithium ions (Li + ) and other metal ions (M n+ ), hydrogen ions (H + ), and hydroxide ions (OH - ) and other anions, such as chloride ion (Cl - ) and sulfate ions (SO4 2- ) etc. are dissolved.

[0004] When a voltage is applied from the power supply 105, the reaction of the following formula (1) occurs in the Li-containing aqueous solution SW in the Li supply chamber 112 near the electrode 141 to generate oxygen (O), and the reaction of the following formula (2) occurs on the surface of the electrolyte membrane 2. - When the electrolyte membrane 2 contains lithium ions (Li), chlorine (Cl2) is further generated near the electrode 141. Meanwhile, in the aqueous solution RS for Li recovery in the Li recovery chamber 113, the reaction of the following formula (3) occurs on the front surface (rear surface) of the electrolyte membrane 2, and the reaction of the following formula (4) occurs near the electrode 142, generating hydrogen (H2). In each formula, the lithium ions (Li + ) to Li + (electrolyte), and other ions (Li + , H + , OH - ) represents the one dissolved in the aqueous solution. The following formula (2) represents the Li in the solution. + represents a reaction in which Li in the electrolyte membrane 2 moves + As a result, the Li contained in each of the Li-containing aqueous solution SW, the electrolyte membrane 2, and the Li recovery aqueous solution RS is + Due to the electrochemical potential difference, Li is extracted from the Li-containing aqueous solution SW. + The electrolyte membrane 2 has a small size of lattice defect site, so Li + Na with a larger diameter than + , Ca 2+ Metal ions M such as n+ Therefore, the Li-containing aqueous solution SW does not allow Li to pass through. + selectively moves to the aqueous solution for Li recovery RS, and Li is introduced into the Li recovery chamber 113. + An aqueous solution of the formula (aqueous lithium hydroxide solution) is obtained.

[0005] Japanese Patent No. 6233877 Japanese Patent Application Laid-Open No. 2019-141807 International Publication No. 2022 / 239864

[0006] Kunugi S., Inaguma Y., Itoh M., "Electrochemical recovery and isotope separation of lithium ion employing lithium ion conductive perovskite-type oxides", Solid State Ionics, Vol. 122, Issues 1-4, pp. 35-39, July 1999

[0007] The method for recovering Li by electrodialysis is as follows: electrons e - In order to release the lithium, an aqueous solution of seawater or an acid containing dissolved waste batteries is used as a Li supply source, and the lithium is decomposed to release an anion, hydroxide ion (OH - ) is generated. On the other hand, Li-containing wastewater generated during the manufacturing process of lithium-ion secondary batteries is primarily an electrolyte solution, a non-aqueous solution in which a Li salt such as LiPF6 is dissolved in an organic solvent such as ethylene carbonate (EC). When attempting to recover Li from such wastewater using electrodialysis, the organic solvent decomposes, making it impossible to recover the organic solvent for reuse. Furthermore, decomposition of the organic solvent requires the application of a high voltage, resulting in a large-scale system. As mentioned above, to recover Li from waste batteries, the batteries are crushed and dissolved in a strong acid such as sulfuric acid (H2SO4). However, if the Li supply source is an aqueous solution with a low pH, the electrodialysis (Li recovery) proceeds slowly. On the other hand, adding sodium hydroxide (NaOH) or the like to achieve a high pH requires neutralization of the highly alkaline aqueous solution after Li extraction before discharge, which, combined with the addition of NaOH, results in high costs. Furthermore, before dissolving the waste batteries in acid, a process of roasting to remove the organic solvent from the electrolyte is required.

[0008] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a lithium recovery method and lithium recovery apparatus that can recover lithium from a non-aqueous solution in which lithium is dissolved in an organic solvent by electrodialysis in a state in which the organic solvent can be recovered.

[0009] That is, the lithium recovery device according to the present invention includes a treatment tank partitioned into a first chamber, a second chamber, and a third chamber in this order, a lithium ion conductive electrolyte membrane dividing the treatment tank into the first chamber and the second chamber, a first ion conductive membrane dividing the treatment tank into the second chamber and the third chamber, a first electrode disposed in the third chamber, a second electrode disposed in a chamber at the end of the treatment tank opposite the third chamber, and a power source having a positive electrode connected to the first electrode and a negative electrode connected to the second electrode, and the lithium ions are transferred 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 conductive membrane conducts at least one type of cation other than lithium ions or at least one type of anion that is water-soluble and contained in the non-aqueous solution, and water is contained in the third chamber.

[0010] Another lithium recovery device according to the present invention comprises: a treatment tank partitioned in this order into a second chamber, a first chamber, and a third chamber; a lithium ion conductive electrolyte membrane dividing the treatment tank into the first chamber and the second chamber; a second ion conductive membrane that does not conduct lithium ions dividing the treatment tank into the first chamber and the third chamber; a first electrode provided in the second chamber; a second electrode provided in the third chamber; and a power source having a positive electrode connected to the first electrode and a negative electrode connected to the second electrode, wherein the lithium ions are transferred from a non-aqueous solution containing lithium ions contained in the second chamber to water or an organic solvent contained in the first chamber, and water is contained in the third chamber, and further water is contained in the second chamber.

[0011] a treatment tank partitioned into five or more compartments by the first ion-conductive membrane, the lithium ion-conductive electrolyte membrane, and the second ion-conductive membrane; a first electrode provided in the compartment at one end of the treatment tank, and a second electrode provided in the compartment at the other end; and a power source having a positive electrode connected to the first electrode and a negative electrode connected to the second electrode. Water is contained in the compartment at one end of the treatment tank, and lithium ions are transferred from a non-aqueous solution containing lithium ions contained at one end of two adjacent compartments partitioned by the lithium ion-conductive electrolyte membrane to water contained at the other end.

[0012] The lithium recovery method according to the present invention is a method for transferring lithium ions contained in a non-aqueous solution contained in a second compartment of a treatment tank partitioned into a first compartment and a second compartment by a lithium ion conductive electrolyte membrane, to water or an organic solvent contained in the first compartment, wherein the treatment tank is further partitioned into the second compartment and a third compartment by a first ion conductive membrane that conducts at least one type of cation other than lithium ions, or at least one type of anion that is water-soluble and contained in the non-aqueous solution, water is contained in the third compartment, and a power supply connected with the first electrode as positive applies a voltage between a first electrode provided in the third compartment and a second electrode provided in a compartment at the end of the treatment tank opposite to the third compartment.

[0013] Another lithium recovery method according to the present invention is a method for transferring lithium ions contained in a non-aqueous solution contained in a second compartment of a treatment tank partitioned into a first compartment and a second compartment by a lithium ion conductive electrolyte membrane to water or an organic solvent contained in the first compartment, wherein water is further contained in the second compartment, and a power supply connected with the first electrode as positive applies a voltage between a first electrode provided in the second compartment and a second electrode provided in a compartment at the opposite end of the partitioned second compartment of the treatment tank.

[0014] Another lithium recovery method according to the present invention is a method for transferring lithium ions from a non-aqueous solution containing lithium ions contained in one of two adjacent compartments separated by the lithium ion conductive electrolyte membranes to water contained in the other compartment in a treatment tank partitioned into five or more compartments by ion conductive membranes and lithium ion conductive electrolyte membranes arranged alternately from one end side, wherein the ion conductive membrane arranged between the lithium ion conductive electrolyte membranes does not conduct lithium ions, water is contained in the compartment at one end of the treatment tank, and a power source connected with the first electrode as positive applies a voltage between a first electrode provided in the compartment at one end of the treatment tank and a second electrode provided in the compartment at the other end, and lithium ions are transferred from the non-aqueous solution containing lithium ions contained in one end of the two adjacent compartments to water contained in the other end.

[0015] According to the lithium recovery device and the lithium recovery method of the present invention, an organic solvent in which a Li salt is dissolved can be used as the Li supply source.

[0016] FIG. 1 is a schematic diagram illustrating the configuration of a lithium recovery apparatus according to a first embodiment of the present invention. FIG. 2 is a schematic diagram illustrating a lithium recovery method according to a first embodiment of the present invention. FIG. 3 is a schematic diagram illustrating a lithium recovery apparatus and a lithium recovery method according to a modified example of the first embodiment of the present invention. FIG. 4 is a schematic diagram illustrating a lithium recovery apparatus according to a second embodiment of the present invention. FIG. 5 is a schematic diagram illustrating a lithium recovery method according to a second embodiment of the present invention. FIG. 6 is a schematic diagram illustrating a lithium recovery apparatus according to a third embodiment of the present invention. FIG. 7 is a schematic diagram illustrating a lithium recovery method according to a third embodiment of the present invention. FIG. 8 is a schematic diagram illustrating a lithium recovery apparatus and a lithium recovery method according to a modified example of the third embodiment of the present invention. FIG. 9 is a schematic diagram illustrating a lithium recovery apparatus and a lithium recovery method according to a fourth embodiment of the present invention. FIG. 10 is a schematic diagram illustrating a lithium recovery method according to the fourth embodiment of the present invention. FIG. 11 is a schematic diagram illustrating a lithium recovery apparatus according to a fifth embodiment of the present invention. FIG. 12 is a schematic diagram illustrating a lithium recovery method according to a fifth embodiment of the present invention. FIG. 13 is a schematic diagram illustrating a lithium recovery apparatus and a lithium recovery method according to a modified example of the fifth embodiment of the present invention. FIG. 14 is a schematic diagram illustrating a lithium recovery apparatus and a lithium recovery method according to a sixth embodiment of the present invention. FIG. 16 is a schematic diagram of the lithium recovery device shown in FIG. 15 , illustrating a lithium recovery method according to a sixth embodiment of the present invention. FIG. 17 is a schematic diagram illustrating the configuration of a lithium recovery device and a lithium recovery method according to a modified example of the sixth embodiment of the present invention. FIG. 18 is a schematic diagram of the multi-chamber lithium recovery device shown in FIG. 18 , illustrating a lithium recovery method according to an embodiment of the present invention. FIG. 19 is a schematic diagram illustrating the configuration of a multi-chamber lithium recovery device and a lithium recovery method according to a modified example of an embodiment of the present invention.Fig. 1 is a schematic diagram illustrating the configuration of a multi-chamber lithium recovery device and a lithium recovery method according to a modified example of an embodiment of the present invention. Fig. 2 is a graph showing the transition of the amount of lithium recovered per hour in an example and a comparative example of a lithium recovery device according to the present invention. Fig. 3 is a schematic diagram of a lithium recovery device illustrating an example of a method for recovering lithium from an aqueous solution by electrodialysis.

[0017] Embodiments of a lithium recovery device and a lithium recovery method according to the present invention will be described with reference to the drawings. In the drawings, the size of certain elements may be exaggerated and the shapes may be simplified for clarity. In addition, in the description of each embodiment, elements that are the same as those in the previous embodiment are given the same reference numerals and descriptions thereof will be omitted as appropriate.

[0018] 1 , a lithium recovery apparatus 1 according to a 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 treatment tank 7 partitioned into three chambers 11, 12, and 13 in this order by the ion exchange membrane 31 and the electrolyte membrane 2, a first electrode 41 provided in a chamber (third chamber) 11 at one end of the treatment tank 7, a second electrode 42 provided in a chamber (first chamber) 13 at the other end, and a power source 5 connected between the electrodes 41 and 42, with the first electrode 41 being positive. The chamber (third chamber) 11 at the end separated by the ion exchange membrane 31 is a first electrode chamber and contains an aqueous solution (water) S1. The central chamber (second chamber) 12 is a Li supply chamber and contains a Li-containing non-aqueous solution FS. The end chamber (first chamber) 13 separated by the electrolyte membrane 2 is a Li recovery chamber, and contains an aqueous solution for Li recovery RS. The lithium recovery device 1 may further include a water supply device 81 that supplies water (aqueous solution S1) to the first electrode chamber 11, and circulation devices 82 and 83 that are provided in the chambers 12 and 13, respectively, as needed. The lithium recovery device 1 recovers lithium ions (Li + ) is transferred to the aqueous Li recovery solution RS contained in the Li recovery chamber 13.

[0019] The Li-containing non-aqueous solution FS is a Li source, and is a solution containing lithium ions (Li + ) and other metal ions M n+ , and their counter ions, anions A n- Examples of such non-aqueous solutions include waste liquid generated in the manufacturing process of lithium ion secondary batteries and solutions obtained by crushing used lithium ion secondary batteries (waste batteries) and dissolving them in an organic solvent. Unlike the case where waste batteries are dissolved in acid to recover metals such as Li, roasting is not required. The Li-containing non-aqueous solution FS is mainly composed of general liquid electrolytes used in lithium ion secondary batteries, and contains Li. + Metal ions other than M n+ The liquid electrolyte may be contaminated with Li, and may further contain organic solvents for cleaning. The liquid electrolyte is a non-aqueous solution in which Li salts such as LiPF6, LiClO4, LiBF4, LiN(CF3SO2)2, and LiN(C2F5SO2)2 are dissolved in organic solvents such as ethylene carbonate (EC), propylene carbonate (PC), γ-butyrolactone, dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), 1,2-dimethoxyethane (DME), and acetonitrile. Similarly to the organic solvents used in the liquid electrolyte, EC, PC, or N-methyl-2-pyrrolidone (NMP) may be used as organic solvents for cleaning or to dissolve waste batteries. In such a non-aqueous solution, the Li salts are dissolved in Li + and its counter ion. + The counter ion is hexafluorophosphate ion (PF6 - ), tetrafluoroborate ion (BF4 - ), bis(fluorosulfonyl)amide ion ((FSO2)2N - ;FSA - ), trifluoromethylsulfonylamide ion ((CF3SO2)2N - ;TFSA - ), perchlorate ion (ClO - The Li-containing non-aqueous solution FS is a solution for dissolving waste batteries. + Metal ions other than M n+is Co 2+ , Fe 2+ , Cu 2+ , Al 3+ , Ni 2+ etc., Li + Similarly, the anion exists as a counter ion.

[0020] The aqueous solution for recovering Li RS is a solution containing Li recovered from the Li-containing non-aqueous solution FS. + In order to selectively obtain only Li from the metals, the aqueous solution for Li recovery RS is + Metal ions other than Na + and the like), and further, an aqueous solution containing no OH - An aqueous solution that does not contain anions other than Li, particularly halide ions, is preferred, and is, for example, pure water at the start of operation of the lithium recovery device 1. + In order to smoothly move the lithium, at the start of operation of the lithium recovery device 1, the aqueous solution for Li recovery RS contains Li + Preferably, the aqueous solution is an aqueous solution containing lithium hydroxide (LiOH).

[0021] The aqueous solution S1 is a solution containing a cation, such as a hydrogen ion (H + The aqueous solution S1 is, for example, pure water at the start of operation of the lithium recovery device 1. + In order to smoothly transfer the lithium to the Li-containing non-aqueous solution FS, the aqueous solution S1 may be an acidic, neutral, or alkaline aqueous solution (electrolyte aqueous solution) having a relatively high electronic conductivity. Furthermore, it is preferable that the aqueous solution S1 does not have a lower pH (S1<RS) than the aqueous solution for Li recovery RS after the start of operation, and it is more preferable that the aqueous solution S1 has a higher pH than the aqueous solution for Li recovery RS. For this reason, it is preferable that the aqueous solution S1 is an alkaline aqueous solution.

[0022] The electrolyte membrane 2 is an electrolyte having lithium ion conductivity, and is provided so as to separate the treatment tank 7 into a Li supply chamber 12 and a Li recovery chamber 13. + and the Li contained in the Li-containing non-aqueous solution FS+ Metal ions other than M n+ is an electrolyte that does not conduct electrons e - More preferably, the electrolyte membrane 2 is an electrolyte made of ceramics having these properties. 2 / 3-x Li 3x Such an electrolyte membrane 2 has a certain proportion of lattice defects, and the size of the lattice defect sites is small, so that Li + Metal ions other than M n+ Li + Since the diameter is larger than the

[0023] The ion exchange membrane 31 is provided to separate the treatment tank 7 into the first electrode chamber 11 and the Li supply chamber 12, and contains at least one type of cation other than lithium ions, for example, H + As a result, H is transferred from the water (HO) in the aqueous solution S1 in the first electrode chamber 11 to the Li-containing non-aqueous solution FS in the Li supply chamber 12. + is supplied. The ion exchange membrane 31 is disposed at a sufficient distance from the electrolyte membrane 2, but preferably the distance between them is not too great. By reducing the distance between the first electrode 41 and the second electrode 42, which are disposed to sandwich the electrolyte membrane 2 and the ion exchange membrane 31 together, it is possible to strengthen the electric field generated in response to the voltage applied by the power supply 5. The ion exchange membrane 31 is resistant to the organic solvent contained in the Li-containing non-aqueous solution FS, and may be a cation exchange membrane that allows cations to pass through and blocks anions, a monovalent cation-selective ion exchange membrane that allows only monovalent cations to pass through, or a bipolar monovalent ion-selective ion exchange membrane that allows monovalent ions to pass through. In addition, when the aqueous solution S1 is H + In the case of a neutral or alkaline aqueous solution containing cations (metal ions) other than those mentioned above, the ion exchange membrane 31 selectively exchanges H +It is preferable to use a hydrogen ion selectively permeable membrane (proton conducting membrane) or a bipolar membrane for water splitting that conducts hydrogen ions (protons). Alternatively, if the aqueous solution S1 is an aqueous solution of calcium hydroxide (Ca(OH)2) in which metal ions with a valence of two or more are dissolved, the ion exchange membrane 31 may be a monovalent cation selectively permeable ion exchange membrane that allows monovalent ions to pass through.

[0024] These ion exchange membranes may be known ones, and examples thereof include Nafion (registered trademark) as a proton conductive membrane and a cation exchange membrane, NEOSEPTA BP-1E (manufactured by ASTOM CORPORATION) as a bipolar membrane for water splitting, SELEMION (registered trademark) CMV, CMVN, CMTE (all manufactured by AGC Engineering Co., Ltd.) and NEOSEPTA CSE (manufactured by ASTOM CORPORATION) as cation exchange membranes, SELEMION (registered trademark) CSO (manufactured by AGC Engineering Co., Ltd.) and CXP-S (manufactured by ASTOM CORPORATION) as monovalent cation permselective ion exchange membranes, and NEOSEPTA CIMS (manufactured by ASTOM CORPORATION) as a bipolar monovalent ion permselective ion exchange membrane.

[0025] The first electrode 41 and the second electrode 42 are electrodes for applying a voltage that generates a lower potential difference on the Li recovery chamber 13 side between both surfaces of the ion exchange membrane 31 and the electrolyte membrane 2. For this purpose, the electrodes 41 and 42 are provided in the chambers 11 and 13 at both ends of the treatment tank 7, respectively.

[0026] As shown in FIG. 1 , the first electrode 41 can be disposed in the first electrode chamber 11 at a distance from the ion exchange membrane 31, allowing the aqueous solution S1 to contact the entire surface of the ion exchange membrane 31. Meanwhile, the shorter the distance between the first electrode 41 and the second electrode 42, the stronger the electric field generated in response to the applied voltage from the power source 5. Therefore, to prevent this distance from becoming excessively large, it is preferable that the distance between the first electrode 41 and the ion exchange membrane 31 is short. The first electrode 41 preferably has a mesh-like shape or the like that allows liquid to pass through, so that the aqueous solution S1 in contact with the surface of the ion exchange membrane 31 in the first electrode chamber 11 is continuously replaced. The first electrode 41 is preferably disposed parallel to the second electrode 42, with dimensions that allow voltage to be applied to a wider 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 even when a voltage is applied during operation of the lithium recovery device 1. The material constituting the first electrode 41 preferably has catalytic activity for the reaction of the following formula (1) when the aqueous solution S1 is pure water or an alkaline aqueous solution, and for the reaction of the following formula (5) when the aqueous solution S1 is a neutral or acidic aqueous solution. Furthermore, the material is preferably easily processed into the shape of the first electrode 41. Platinum (Pt), for example, is a preferred example of such an electrode material.

[0027] The second electrode 42 is provided in the Li recovery chamber 13 in contact with or spaced apart from the electrolyte membrane 2, preferably disposed parallel to and at a closer distance from the electrolyte membrane 2, and more preferably in contact with the electrolyte membrane 2 as shown in FIG. 1 . The second electrode 42 preferably has dimensions that allow a voltage to be applied to a wider area of ​​the electrolyte membrane 2. The second electrode 42 also preferably has a porous structure, such as a mesh-like structure, through which a liquid can pass, so that the aqueous Li recovery solution RS contacts a sufficient area of ​​the surface (rear surface) of the electrolyte membrane 2 facing the Li recovery chamber 13 and so that the aqueous Li recovery solution RS in contact with the rear surface of the electrolyte membrane 2 in the Li recovery chamber 13 is continuously replaced. The second electrode 42 may be formed directly on one side of the electrolyte membrane 2, or may be fixed to the treatment tank 7 with a jig so as to be in contact with the electrolyte membrane 2. The second electrode 42 is formed of an electrode material that is electronically conductive and stable in the aqueous Li recovery solution RS even when a voltage is applied, including after the lithium recovery device 1 is operated (after Li recovery). The material constituting the second electrode 42 is preferably a material having catalytic activity for the reaction of the following formula (4), and when the second electrode 42 is provided in contact with the electrolyte membrane 2, it is also preferably a material having catalytic activity for the reaction of the following formula (3). Furthermore, it is preferable that the material be easily processed into the shape of the second electrode 42. As such an electrode material, for example, platinum (Pt) is preferable, or carbon (C), copper (Cu), nickel (Ni), or stainless steel, which are stable at a potential lower than the potential at which the reaction of the following formula (4) occurs, can also be used, and more preferably, these materials have Pt fine particles supporting their surfaces, which function as a catalyst.

[0028] The power supply 5 is a DC power supply device, and is connected between the electrodes 41 and 42 with the Li recovery chamber 13 side being negative. That is, the positive electrode of the power supply 5 is connected to the first electrode 41, and the negative electrode is connected to the second electrode 42. The power supply 5 applies a voltage between both surfaces of the ion exchange membrane 31 and the electrolyte membrane 2, respectively, to convert the H contained in the aqueous solution S1 into + is transferred to the Li-containing non-aqueous solution FS, and the electrolyte membrane 2 is + This creates a potential gradient for the conduction of

[0029] The treatment tank 7 is made of a material that does not dissolve, corrode, or otherwise deteriorate when it comes into contact with the Li-containing non-aqueous solution FS and the aqueous solution for Li recovery RS, including the aqueous solution for Li recovery after operation of the lithium recovery apparatus 1 (after Li recovery). For example, the aqueous solution for Li recovery RS becomes an aqueous solution of lithium hydroxide (LiOH). Examples of such materials that can be used include glass, stainless steel, PP (polypropylene), and PEEK (polyether ether ketone) resin. The treatment tank 7 is not particularly limited in shape, etc., as long as it has a volume corresponding to the required treatment capacity.

[0030] The water supply device 81 is a device that supplies water to the first electrode chamber 11 and replenishes the water that is lost in the aqueous solution S1 due to the reaction of formula (1) or formula (5) during operation. The water supply device 81 may supply pure water, or may supply the aqueous solution S1 or an ionic compound, and can adjust the pH and conductivity of the aqueous solution S1. Note that while FIG. 1 shows the water supply device 81 supplying water from above the treatment tank 7, this is a schematic example and the arrangement and structure are not specified.

[0031] The circulation device 82 circulates the Li-containing non-aqueous solution FS so that it is continuously replaced within the Li supply chamber 12 during operation. The circulation device 82 includes a circulation tank provided outside the treatment tank 7 and a pump that circulates the Li-containing non-aqueous solution FS between the tank and the Li supply chamber 12. That is, the circulation device 82 is not limited in configuration as long as it is arranged so that the pump can circulate or supply the liquid within the circulation tank via a circulation path such as a pipe connected to the Li supply chamber 12. Note that in FIG. 1 , the circulation device 82 is shown below the treatment tank 7 and supplies and discharges the Li-containing non-aqueous solution FS from the bottom of the treatment tank 7, but this is merely a schematic illustration and the location and structure are not intended to be specific. The circulation device 83 is similar. The circulation device 82 also agitates the Li-containing non-aqueous solution FS within the Li supply chamber 12 so that the Li-containing non-aqueous solution FS in contact with the electrolyte membrane 2 is continuously replaced, and furthermore, compensates for a decrease in the amount of liquid within the Li supply chamber 12 as necessary. Furthermore, the circulation device 82 can supply a large amount of Li-containing non-aqueous solution FS relative to the volume of the Li supply chamber 12 of the treatment tank 7, and the Li content of the Li-containing non-aqueous solution FS during operation can be reduced. +As described above, in this embodiment, in order to shorten the gap 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, i.e., the volume of the Li supply chamber 12 is not large. Alternatively, the circulation device 82 may be configured as needed, such as by using an agitator 8 (see FIG. 12 ) equipped with a screw that rotates within the Li supply chamber 12.

[0032] The circulation device 83 circulates the Li recovery aqueous solution RS so that it is continuously replaced within the Li recovery chamber 13, and compensates for a decrease in the amount of liquid within the Li recovery chamber 13, and can have the same configuration as the circulation device 82. During operation, water decreases in the Li recovery aqueous solution RS due to the reaction of formula (4), so the circulation device 83 compensates for the decrease. In addition, the circulation device 83 stirs the Li recovery aqueous solution RS within the Li recovery chamber 13 so that the Li recovery aqueous solution RS in contact with the electrolyte membrane 2 and the second electrode 42 is continuously replaced. The circulation device 83 further agitates the Li in the Li recovery aqueous solution RS. + The circulation device 83 may be provided with a settling tank for settling the lithium ions, and a filter for preventing the precipitate from returning to the Li recovery chamber 13. Alternatively, the circulation device 83 may be a water supply device that supplies water to the Li recovery chamber 13, such as the water supply device 81, and may further be provided with an agitator 8 having a screw that rotates in the Li recovery chamber 13 (see FIG. 12 ).

[0033] The lithium recovery device 1 may be provided with a liquid level sensor or the like to detect fluctuations in the amount of liquid in each of the chambers 11, 12, and 13 during operation. The lithium recovery device 1 may also be provided with a pH meter that measures the pH of each of the aqueous solutions S1 and RS during operation.

[0034] Furthermore, if carbon dioxide (CO2) in the atmosphere unintentionally dissolves in the Li recovery aqueous solution RS during operation, resulting in the precipitation of lithium carbonate (Li2CO3) or the like, the conductivity of the Li recovery aqueous solution RS will decrease, which is undesirable. To prevent this, the lithium recovery device 1 is preferably configured so that the Li recovery aqueous solution RS is not exposed to the atmosphere. Furthermore, since O2 and H2 are generated from the first electrode chamber 11 and the Li recovery chamber 13, respectively, due to the reaction of formula (1) or formula (5) and the reaction of formula (4), respectively, the lithium recovery device 1 is preferably provided with an exhaust means for venting these gases to prevent them from filling the interior. Furthermore, if the Li-containing non-aqueous solution FS contains a volatile organic solvent, combustible, flammable, or toxic gases such as ethylene (C2H4) and propylene (C3H6) may be generated from the Li supply chamber 12. Therefore, it is preferable for safety reasons to provide a means for recovering these gases without filling the interior and without leaking them. For this reason, it is preferable that the lithium recovery device 1 be provided with check valves, for example, in each of the chambers 11, 12, and 13 of the treatment tank 7 so that gases generated from the liquids S1, FS, and RS can be exhausted to the outside of the treatment tank 7 and outside air cannot be allowed to flow in.

[0035] The lithium recovery device 1 may further include a heating device or a cooling device for heating or cooling at least one of the aqueous solution for Li recovery RS and the Li-containing non-aqueous solution FS. The heating device or the cooling device controls the temperature of one of the solutions RS and FS, and via the other solution, the electrolyte membrane 2. The heating device or the cooling device may be a known device for heating or cooling a liquid. For example, it may be an immersion type (submersion type) that is immersed in the aqueous solution for Li recovery RS in the Li recovery chamber 13, or it may heat or cool the solutions RS and FS in the circulation tanks of the circulation devices 82 and 83, and preferably has a temperature adjustment function. The heating device or the cooling device may be configured to maintain the electrolyte membrane 2 at a predetermined temperature. The aqueous solution for Li recovery RS and the Li-containing non-aqueous solution FS do not need to be maintained at a uniform temperature, but should be above their respective freezing points and below their respective boiling points. As will be described later, the higher the temperature of the electrolyte membrane 2, the greater the amount of Li in the electrolyte membrane 2. +On the other hand, when 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 that accompanies voltage application (operation).

[0036] (Lithium recovery method) A lithium recovery method according to a first embodiment of the present invention will be described with reference to Fig. 2. The lithium recovery method according to this embodiment is performed as follows using a lithium recovery apparatus 1. Note that in Fig. 2, a water supply device 81 and circulation devices 82 and 83 are omitted.

[0037] 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. The application of the voltage +V1 causes the following reaction in the aqueous solution S1 in the first electrode chamber 11: hydroxide ions (OH) in water (HO) are converted to hydroxide ions (OH) in the aqueous solution S1 near the first electrode 41. - ) undergoes the reaction of the following formula (1), generating water (H2O) and oxygen (O2), and electrons e - However, when 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), and H + and O2 is generated. OH - Decrease in H + As the charge increases, hydrogen ions (H + ) permeates the ion exchange membrane 31 and moves to the Li-containing non-aqueous solution FS in the Li supply chamber 12, causing the reaction of the following formula (6). In each formula, the hydrogen ions (H + ) to H + (non-aq.), and other ions (H + , OH - ) indicates that the substance is dissolved in water or an aqueous solution.

[0038] In the Li-containing non-aqueous solution FS in the Li supply chamber 12, an electric field is generated in a direction from the ion exchange membrane 31 side to the electrolyte membrane 2 side by applying a voltage +V1, and the Li, which is a cation in the Li-containing non-aqueous solution FS, + , M n+is attracted to the surface (front surface) of the electrolyte membrane 2 on the Li supply chamber 12 side by electrostatic attraction. + In order to maintain the charge balance, the Li in the Li-containing non-aqueous solution FS is transferred (reaction of formula (6)). + The reaction of the following formula (7), in which lithium ions (Li) move into the electrolyte membrane 2, occurs near the surface of the electrolyte membrane 2. In formula (7), the lithium ions (Li) dissolved in the organic solvent + ) to Li + (non-aq.).

[0039] On the other hand, in the aqueous solution RS for Li recovery in the Li recovery chamber 13, the following reaction occurs due to the application of the voltage +V1. In the vicinity of the second electrode 42, H2O in the aqueous solution RS for Li recovery converts to electrons e - By supplying hydrogen (H) and OH, the reaction of the following formula (4) occurs. - In the aqueous solution RS for Li recovery, OH - As a result of the increase in the amount of Li in the electrolyte membrane 2, in order to maintain the charge balance, + In the Li recovery aqueous solution RS, the reaction of the following formula (3) occurs, in which the reactant is transferred to the Li recovery aqueous solution RS. In the Li recovery aqueous solution RS, the reaction of the following formula (3) and the reaction of the following formula (4) are combined to cause the reaction of the following formula (8).

[0040] From the reaction of formula (7) to the reaction of formula (3), that is, Li in the Li-containing non-aqueous solution FS + penetration of Li from the surface of the electrolyte membrane 2 to the inside, + and Li in the electrolyte membrane 2 + The transfer of Li to the aqueous solution RS for Li recovery proceeds as follows: By applying a voltage +V1, the Li in the Li-containing non-aqueous solution FS is transferred as shown in the reaction of formula (7). + penetrates into the lattice defect sites on the surface (front surface) of the electrolyte membrane 2 on the Li supply chamber 12 side. Then, by applying the voltage +V1, the electrolyte membrane 2 has a potential gradient where the potential on the surface (back surface) on the opposite side (Li recovery chamber 13 side) is low, so the Li that has penetrated into the lattice defect sites on the surface +Li jumps (hops) to the lattice defect site in the vicinity of the deeper part of the electrolyte membrane 2. + The Li atoms in the lattice defect sites on the surface of the electrolyte membrane 2 are transferred to the adjacent lattice defect sites repeatedly, and finally transferred from the lattice defect sites on the back surface into the aqueous solution RS for Li recovery as shown in the reaction of formula (3). + As a result of the migration of Li to the depth of the electrolyte membrane 2, another Li that had been adsorbed in the vicinity of the vacant lattice defect site was absorbed. + and Li in Li-containing non-aqueous solution FS + has infiltrated these Li + moves through the electrolyte membrane 2 in the same manner.

[0041] In the lithium recovery method according to this embodiment, by setting the voltage V1 to a voltage at which the electrolysis reaction of water occurs or higher, the reaction of formula (1) or formula (5) and the reaction of formula (4) occur, and Li + moves through the electrolyte membrane 2. The voltage (electrolysis voltage) at which the electrolysis reaction of water occurs is +1.229 V (25° C.) when the aqueous solution S1 and the aqueous solution for Li recovery RS have the same pH (hydrogen ion concentration), and in reality, the voltage V1 needs to be set to a value several hundred mV higher than the theoretical voltage of 1.229 V, depending on the electrode performance and the like that determine the electrode reaction overvoltage of each of the electrodes 41 and 42. Furthermore, the higher the pH of the aqueous solution for Li recovery RS relative to the aqueous solution S1, the higher the electrolysis voltage becomes.

[0042] Furthermore, as the voltage V1 increases, the reaction rates of the reaction of formula (1) or (5) and the reaction of formula (4) increase, and accordingly the reaction rates of the reaction of formula (7) and the reaction of formula (3) increase. Also, the electric field generated in the Li-containing non-aqueous solution FS in the Li supply chamber 12 becomes stronger, and Li is concentrated near the surface of the electrolyte membrane 2. + In addition, the potential gradient between both sides of the electrolyte membrane 2 increases, and Li + The amount of movement per unit time (Li + However, the potential difference between both sides of the electrolyte membrane 2 reduces some of the metal ions that make up the electrolyte membrane 2 (for example, if the electrolyte membrane 2 is LLTO, Ti 4++e - →Ti 3+ ) voltage or more, the electrolyte membrane 2 transfers electrons e from the Li recovery chamber 13 side to the Li supply chamber 12 side. - As a result, most of the applied electrical energy is transferred to electrons e - is consumed in the conduction of Li + The voltage dependence of mobility is reduced, and Li + The energy efficiency of the movement of the electrolyte membrane 2 drops sharply (see Patent Document 2). This phenomenon is particularly likely to occur with transition metal ions among the metal ions that make up the electrolyte membrane 2.

[0043] In the lithium recovery device 1 according to this embodiment, at least the first electrode 41 of the first electrode 41 and the second electrode 42 is disposed at a distance from the electrolyte membrane 2. This keeps the potential difference between both sides of the electrolyte membrane 2 small relative to the voltage V1, making it difficult for the electrolyte membrane 2 to exhibit electronic conductivity (see Patent Document 2). However, if the voltage V1 is increased to a certain level, the potential difference between the two sides of the electrolyte membrane 2 reaches a potential difference at which the electrolyte membrane 2 exhibits electronic conductivity. Therefore, it is preferable to set the voltage V1 below this voltage. The relationship between the voltage V1 and the potential difference between the two sides of the electrolyte membrane 2 depends on the distance between the first electrode 41 and the ion exchange membrane 31, the distance between the second electrode 42 and the electrolyte membrane 2, the distance between the ion exchange membrane 31 and the electrolyte membrane 2 (the length of the Li supply chamber 12), and the electronic conductivities of the aqueous solution S1 and the aqueous solution RS for Li recovery. In particular, + As the recovery of Li progresses, the Li in the aqueous solution for Li recovery 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 surfaces of the electrolyte membrane 2 increases, approaching voltage V1. Therefore, it is preferable to set voltage V1 in consideration of the electronic conductivity of the Li recovery aqueous solution RS during operation.

[0044] In addition, in the case of recovering Li by electrodialysis, Li + The mobility of Li to the supply side of the electrolyte membrane + Since the diffusion rate is limited by the diffusion of Li in the supply solution, + When the concentration is low, even if the applied voltage (V1) between both sides of the electrolyte membrane is increased, +In this embodiment, as described above, the electric field generated in the Li-containing non-aqueous solution FS in the Li supply chamber 12 causes the Li + The concentration becomes relatively high near the surface of the electrolyte membrane 2, and energy efficiency can be improved.

[0045] Li in the electrolyte membrane 2 + The movement of the electrolyte membrane 2 is accelerated not only by the voltage V1 but also by the temperature. Therefore, it is preferable that the temperature of the electrolyte membrane 2 is high. Furthermore, the resistance of the aqueous solution S1 and the aqueous solution for Li recovery RS decreases as the temperature increases. The applicable temperature range of the electrolyte membrane 2 is equal to or higher than the freezing point and lower than the boiling point of the solutions S1, FS, and RS, and is preferably 20°C or higher.

[0046] In the lithium recovery method according to the present invention, as the operation 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 for Li recovery RS in the Li recovery chamber 13 decreases due to the reaction of formula (4). In addition, the Li-containing non-aqueous solution FS in the Li supply chamber 12 may decrease due to the evaporation of the organic solvent. Therefore, it is preferable that the water supply device 81 and the circulation devices 82 and 83 operate to maintain the liquid volume in each of the chambers 11, 12, and 13, for example, by detecting the liquid level with a liquid level sensor or by setting a timer. In the lithium recovery device 1, it is preferable that the liquid levels in the chambers 11, 12, and 13 are uniform during operation. In addition, as the operation time passes, the Li content of the aqueous solution for Li recovery RS decreases. + Since the pH increases with an increase in concentration, the pH of the aqueous solution S1 may be increased accordingly to suppress an increase in the electrolysis voltage. To achieve this, for example, an alkali such as sodium hydroxide (NaOH) is supplied to the first electrode chamber 11 during operation.

[0047] After the operation is completed, the aqueous solution for Li recovery RS in the Li recovery chamber 13 and the circulation tank of the circulation device 83 can be concentrated by evaporating water as needed, and then generating and precipitating lithium carbonate (Li2CO3) by carbon dioxide (CO2) bubbling or the like, thereby recovering Li. Alternatively, the aqueous solution for Li recovery RS can be cooled or the water can be evaporated to bring it into a supersaturated state, thereby generating and precipitating lithium hydroxide (LiOH), thereby recovering Li. Furthermore, during operation, Li can be recovered by evaporating Li in the settling tank of the circulation device 83. + Alternatively, the lithium recovery solution RS may be precipitated as lithium carbonate or the like. With this configuration, it is possible to prevent the pH of the aqueous solution for Li recovery RS from increasing during operation of the lithium recovery device 1.

[0048] Similarly, after the operation is completed, Li is extracted from the Li-containing non-aqueous solution FS in the Li supply chamber 12 and the circulation tank of the circulation device 82. + Metal ions other than M n+ The organic solvent can be recovered by a known method appropriate for each of them.

[0049] In this embodiment, the aqueous solution S1 contained in the first electrode chamber 11 may be an aqueous solution other than pure water, as described above. + In the case of a neutral or alkaline aqueous solution containing cations (metal ions) other than + However, depending on the type of metal ion, when it moves from the aqueous solution S1 to the Li-containing non-aqueous solution FS, it may precipitate without dissolving, and may block the surface of the ion exchange membrane 31 on the Li supply chamber 12 side, thereby reducing efficiency. Furthermore, if metal ions are supplied from the aqueous solution S1 to the Li-containing non-aqueous solution FS, it may not be efficient to recover an organic solvent from the Li-containing non-aqueous solution FS after the operation is completed. Therefore, as described above, the lithium recovery device 1 is configured to have a structure in which metal ions contained in the aqueous solution S1 do not permeate, i.e., the metal ions do not permeate from the aqueous solution S1 to the Li-containing non-aqueous solution FS. + It is preferable that the ion exchange membrane 31 be a proton conducting membrane or a bipolar membrane through which only ions permeate.

[0050] Or, aqueous solution S1 to H+ When metal ions are transferred to the Li-containing non-aqueous solution FS, the metal ions contained in the aqueous solution S1 are transferred to the Li-containing non-aqueous solution FS. + The ion-exchange membrane 31 is preferably a non-ionic surfactant that can be dissolved in the Li-containing non-aqueous solution FS in an ionic state. + Similarly, PF6 - and BF4 - Na with as counter ion + The aqueous solution S1 can be an aqueous solution of sodium hydroxide (NaOH) or sodium chloride (NaCl). - If the aqueous solution S1 contains Cl, platinum chloride (PtCl) is formed on the surface of the first electrode 41 made of Pt as the operation time progresses, impairing the high catalytic activity of Pt and increasing the electrode reaction overvoltage. - When the aqueous solution S1 is an aqueous NaOH solution or an aqueous NaCl solution, the application of a voltage +V1 reduces the H + In the same way that Na moves to the Li-containing non-aqueous solution FS (reaction of formula (6)), + passes through the ion exchange membrane 31 and moves to the Li-containing non-aqueous solution FS. + together with metal ions (e.g., Na + ) to the Li-containing non-aqueous solution FS, the pH of the aqueous solution S1 decreases with the passage of operation due to a decrease in water caused by the reaction of formula (1) or formula (5) as well as a decrease in metal ions. Therefore, if necessary, during operation, in addition to the supply of pure water by the water supply device 81, NaOH or the like may be supplied to the first electrode chamber 11 in order to maintain or increase the pH of the aqueous solution S1.

[0051] In this embodiment, the medium for recovering Li contained in the Li recovery chamber 13 is not limited to water or an aqueous solution, and a non-aqueous solution may also be used. The non-aqueous solution for recovering Li is a solution in which Li is converted into lithium ions (Li + ) in a non-aqueous solution, and the Li-containing non-aqueous solution can be dissolved in an organic solvent such as EC, which is used for the Li-containing non-aqueous solution FS. + PF6, which is the counter ion of- Anions A such as n- Preferably, the non-aqueous solution is a solution containing Li dissolved therein, similarly to the aqueous solution RS for recovering Li. + The non-aqueous solution RSA for Li recovery may be a non-aqueous solution of Li salt such as LiPF6, or may be a non-aqueous solution such as hexafluorophosphoric acid (HPF6) or tetrafluoroboric acid (HBF4). The second electrode 42 is formed of an electrode material that is stable in the non-aqueous solution RSA for Li recovery even when a voltage is applied. When the non-aqueous solution RSA for Li recovery is contained in the Li recovery chamber 13, application of a voltage +V1 causes the Li in the electrolyte membrane 2 to be dissolved in the non-aqueous solution RSA for Li recovery, just like the aqueous solution RS for Li recovery. + Furthermore, the reaction of the following formula (9) occurs: + When the salts of HPF6 and HBF4 are sufficiently dissolved, the reaction of the following formula (4) occurs near the second electrode 42 to generate H2. n- Li + As a counter ion in the vicinity of the atom, charge neutrality is maintained and no change occurs.

[0052] (First Modification) When the non-aqueous solution RSA for Li recovery is stored in the Li recovery chamber 13 as described above, + As shown in Fig. 3, a lithium recovery apparatus 1A according to a modification of the first embodiment of the present invention includes a second electrode 42A provided apart from the electrolyte membrane 2, and a non-aqueous RSA solution for Li recovery is accommodated in a Li recovery chamber 13. The lithium recovery apparatus 1A according to this modification may include a water supply device 81 and circulation devices 82 and 83 (not shown), similar to the lithium recovery apparatus 1 according to the embodiment shown in Fig. 1.

[0053] In this modification, the potential of the second electrode 42A is set to Li + The voltage +V1 is applied to the second electrode 42A at a reduction potential (-3.05 V vs. SHE) or less. In the non-aqueous RSA solution for Li recovery, in addition to the reaction of the following formula (9), electrons e - By supplying Li+ As a result, metallic Li is deposited on the surface of the second electrode 42A, which makes it easy to recover Li after the operation is completed. In this modification, the organic solvent of the non-aqueous solution for Li recovery RSA has a LUMO (Lowest Unoccupied Molecular Orbital) potential lower than the potential of the second electrode 42A, i.e., Li + It is preferable to use an organic solvent having a reduction potential lower than that of the organic solvent by a certain degree. Specific examples include EC, PC, DMC, and NMP.

[0054] The second electrode 42A is formed of an electrode material that is electronically conductive and stable in the non-aqueous RSA solution for Li recovery even when a voltage is applied. The material constituting the second electrode 42A preferably also has catalytic activity for the reaction of formula (10), and preferably facilitates the recovery of metallic Li deposited on the surface. Alternatively, the second electrode 42A may be formed of high-purity metallic Li, which particularly facilitates the recovery of Li after the end of operation. The second electrode 42A preferably has a mesh-like shape, similar to the first electrode 41, so that the non-aqueous RSA solution for Li recovery in contact with the back surface of the electrolyte membrane 2 in the Li recovery chamber 13 is continuously replaced. The second electrode 42A is provided in the Li recovery chamber 13 at a distance from the electrolyte membrane 2, and is preferably arranged parallel to the electrolyte membrane 2.

[0055] Here, Li + The reduction potential of the electrolyte membrane 2 is the reduction potential of the metal ions constituting the electrolyte membrane 2 (if the electrolyte membrane 2 is LLTO, Ti 4+ +e - →Ti 3+ 2, when the second electrode 42 is provided in contact with the electrolyte membrane 2, the surface of the electrolyte membrane 2 on the Li recovery chamber 13 side becomes the same potential as the second electrode 42, and becomes a forced reduction potential that is lower than the reduction potential of the metal ions. 4+ +e - →Ti 3+As a result, Joule heat loss due to electron conduction increases in the electrolyte membrane 2, significantly reducing energy efficiency. In addition, as operation progresses, metallic Li precipitates on the surface of the second electrode 42, blocking the pores of the second electrode 42 and the surface of the electrolyte membrane 2 facing the Li recovery chamber 13, resulting in the formation of Li. + The mobility of the second electrode 42A decreases. Therefore, after a certain period of operation, it is necessary to remove metallic Li from the surface of the second electrode 42, which is not preferable from the viewpoint of productivity. Therefore, it is preferable that the second electrode 42A is disposed at a distance from the electrolyte membrane 2 so that the surface of the electrolyte membrane 2 facing the Li recovery chamber 13 has a higher potential than the reduction potential of the metal ions constituting the electrolyte membrane 2 when the voltage +V1 is applied.

[0056] In order to recover metallic Li in the Li recovery chamber 13, anions A n- An organic solvent that does not contain Li can be stored in the Li recovery chamber 13. In this case, since the organic solvent does not have electronic conductivity, a second electrode 42 is provided in contact with the electrolyte membrane 2, as in the first embodiment. + When the organic solvent in the Li recovery chamber 13 (reaction of formula (9)) is transferred to the organic solvent in the Li recovery chamber 13, it is immediately reduced (reaction of formula (10)). However, as mentioned above, this is not energy efficient and does not result in good productivity. The organic solvent in the Li recovery chamber 13 is contained to prevent the deposited metallic Li from being oxidized or burned, and any medium that is low in reactivity (non-reactive) with Li may be used, such as argon (Ar) gas.

[0057] (Second Modification) Anion A contained in Li-containing non-aqueous solution FS n- BF4 - , TFSA - In the case where water-soluble anions such as those mentioned above are contained in the lithium recovery device 1 according to the first embodiment, the aqueous solution (water) S1 contained in the first electrode chamber 11 can also be used as a recipient of the anions from the Li-containing non-aqueous solution FS. For this reason, as shown in FIG. 4, the lithium recovery device 1C according to the modified example of the first embodiment of the present invention has an ion exchange membrane 31 for receiving the anions A instead of the ion exchange membrane 31 of the lithium recovery device 1 according to the first embodiment. n-The lithium recovery apparatus 1C may also include a water supply device 81 and circulation devices 82 and 83 (not shown), similar to the lithium recovery apparatus 1 according to the embodiment shown in FIG.

[0058] The anion exchange membrane 32 is a membrane containing an anion A that is contained in the Li-containing non-aqueous solution FS and is water-soluble. n- The first electrode chamber 11 and the Li supply chamber 12 are separated by the anion exchange membrane 32, and thus the anions A of the Li-containing non-aqueous solution FS in the Li supply chamber 12 are conducted. n- can migrate into the aqueous solution S1 in the first electrode chamber 11. The anion exchange membrane 32 is resistant to the organic solvent contained in the Li-containing non-aqueous solution FS. A known anion exchange membrane can be used as the anion exchange membrane 32, for example, SELEMION (registered trademark) AMV (manufactured by AGC Engineering Co., Ltd.) or NEOSEPTA ASE (manufactured by Astom Corporation). The arrangement of the anion exchange membrane 32 in the lithium recovery apparatus 1C and other configurations are the same as those of the ion exchange membrane 31 in the above embodiment.

[0059] The aqueous solution S1 contained in the first electrode chamber 11 can be pure water or an acidic, neutral, or alkaline aqueous solution, as in the above embodiment. However, the anions A contained in the Li-containing non-aqueous solution FS and permeating the anion exchange membrane 32 are n- It is preferable that the catalyst does not contain metal ions or the like that react with the catalyst to form precipitates.

[0060] In the lithium recovery method using the lithium recovery apparatus 1C, similarly to the method using the lithium recovery apparatus 1 according to the above embodiment, the power source 5 applies a positive voltage V1 (+V1) to the first electrode 41 relative to the second electrode 42. The application of the voltage +V1 causes a reaction of the following formula (1) or (5) to occur in the aqueous solution S1 in the first electrode chamber 11 near the first electrode 41, similarly to the above embodiment, to generate O2. In the lithium recovery apparatus 1C, the OH - Decrease in H + As the amount of anion A in the Li-containing non-aqueous solution FS in the Li supply chamber 12 increases, the amount of anion A in the Li-containing non-aqueous solution FS in the Li supply chamber 12 is increased to maintain the charge balance. n-The anion A dissolved in the organic solvent reacts with the anion A in the anion exchange membrane 32. n- A n- (non-aq.).

[0061] In the Li-containing non-aqueous solution FS in the Li supply chamber 12, as in the above embodiment, the Li in the Li-containing non-aqueous solution FS is + , M n+ are attracted to the surface of the electrolyte membrane 2 by electrostatic attraction. n- In order to maintain the charge balance, the Li in the Li-containing non-aqueous solution FS is reduced by the movement of the Li to the aqueous solution S1 in the first electrode chamber 11 (reaction of formula (11)). + The reaction of the following formula (7), in which the ions migrate into the electrolyte membrane 2, occurs near the surface of the electrolyte membrane 2.

[0062] On the other hand, in the aqueous solution RS for Li recovery in the Li recovery chamber 13, a reaction of the following formula (4) occurs in the vicinity of the second electrode 42, similar to the above embodiment, to form H and OH. - In order to generate and maintain the charge balance, Li in the electrolyte membrane 2 + is transferred to the aqueous solution RS for recovering Li, thereby causing a reaction of the following formula (3): In this way, the lithium recovery device 1C can recover Li in the same way as the lithium recovery device 1 according to the above embodiment.

[0063] In this modified example, as the operation time progresses, the aqueous solution S1 loses water due to the reaction of formula (1) or formula (5), and the anions A that have migrated from the Li-containing non-aqueous solution FS also increase. n- Therefore, the pH of the aqueous solution S1 may be adjusted during operation as needed.

[0064] In the lithium recovery apparatus 1C, as in the lithium recovery apparatus 1 according to the above embodiment, the non-aqueous solution RSA for Li recovery can be accommodated in the Li recovery chamber 13, and further, as in the lithium recovery apparatus 1A according to the above modified example (see FIG. 3), a second electrode 42A can be provided to recover metallic lithium.

[0065] According to the lithium recovery device of the first embodiment and its modified example, a first electrode chamber is provided on the Li supply side of the Li supply chamber of the treatment tank, separated by an ion conductive membrane, and water is stored in the first electrode chamber, whereby O2 is generated from the water, making it possible to recover Li from a non-aqueous solution by electrodialysis.

[0066] [Second embodiment] In the lithium recovery device according to the first embodiment, it is preferable to suppress the voltage applied between both sides of the lithium ion conductive electrolyte membrane so as to obtain a potential difference that does not cause the lithium ion conductive electrolyte membrane to exhibit electronic conductivity. + The lithium ion recovery device and the lithium recovery method according to the second embodiment of the present invention are described below.

[0067] (Lithium Recovery Apparatus) As shown in FIG. 5 , a lithium recovery apparatus 1B according to a 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 treatment tank 7 partitioned into three chambers 11, 12, and 13 in this order by the ion exchange membrane 31 and the electrolyte membrane 2, a first electrode 41 provided in a first electrode chamber (third chamber) 11 at one end of the treatment tank 7, a third electrode 43 provided in contact with the electrolyte membrane 2 in a Li recovery chamber (first chamber) 13 at the other end, and a second electrode 42B provided spaced apart from the third electrode 43, and a power source 5B connected between the electrodes 41 and 42B, with the first electrode 41 as positive. The power source 5B includes a first power source 51 and a second power source 52 connected in series to the negative electrode of the first power source 51, and the third electrode is connected to the negative electrode of the first power source 51. The first electrode chamber (third chamber) 11 contains an aqueous solution S1, the Li supply chamber (second chamber) 12 contains a Li-containing non-aqueous solution FS, and the Li recovery chamber (first chamber) 13 contains an aqueous solution RS for Li recovery. The lithium recovery apparatus 1B may further include a water supply device 81 and circulation devices 82 and 83, as necessary. The lithium recovery apparatus 1B may further include a heating device, a cooling device, a liquid level sensor, a pH meter, an exhaust means, and the like, similar to the lithium recovery apparatus 1 according to the first embodiment. The lithium recovery apparatus 1B according to this embodiment differs from the lithium recovery apparatus 1 according to the first embodiment shown in FIG. 1 in that the power source 5B is formed by connecting two power sources 51 and 52 in series, a second electrode 42B is provided in the Li recovery chamber 13 separate from the electrolyte membrane 2, and a third electrode 43 is further added to the Li recovery chamber 13 and connected to the negative electrode of the first power source 51 (the positive electrode of the second power source 52) and in contact with the electrolyte membrane 2.

[0068] The second electrode 42B is an electrode paired with the first electrode 41 for applying a voltage and for forming a lower potential in the Li recovery aqueous solution RS than the rear surface of the electrolyte membrane 2. Therefore, the second electrode 42B is disposed in the Li recovery chamber 13 so as not to contact the electrolyte membrane 2 and the third electrode 43 provided in contact with the electrolyte membrane 2, but facing the third electrode 43, preferably parallel to the third electrode 43. Furthermore, as described below, the second electrode 42B is preferably disposed close enough to the third electrode 43 to prevent short-circuiting. The second electrode 42B preferably has a mesh-like shape or the like to increase the contact area with the Li recovery aqueous solution RS. The second electrode 42B is formed of an electrode material that is electronically conductive and stable in the Li recovery aqueous solution RS even when a voltage is applied. This material preferably has catalytic activity for the reaction represented by the following formula (4). That is, the second electrode 42B can be formed using the same electrode material as the second electrode 42 of the first embodiment.

[0069] The third electrode 43 is an electrode paired with the first electrode 41 for applying a voltage between the respective surfaces of the ion exchange membrane 31 and the electrolyte membrane 2, and is also an electrode for relatively increasing the potential of the surface of the electrolyte membrane 2 facing the Li recovery chamber 13 in the Li recovery aqueous solution RS. For this purpose, the third electrode 43 is provided in contact with or spaced apart from the surface of the electrolyte membrane 2 facing the Li recovery chamber 13, preferably closer to the electrolyte membrane 2. More preferably, the third electrode 43 has a porous structure similar to the second electrode 42 of the lithium recovery device 1 according to the first embodiment (see FIG. 1 ) and is provided in contact with the electrolyte membrane 2. The third electrode 43 is formed of an electrode material that is electronically conductive and stable in the Li recovery aqueous solution RS even when a voltage is applied. This material preferably has catalytic activity for the reactions of the following formulas (1) and (3). Platinum (Pt), for example, is a preferred example of such an electrode material.

[0070] The power supply 5B is formed by connecting a first power supply 51 and a second power supply 52 in series, and each of the power supplies 51 and 52 is a DC power supply, similar to the power supply 5 in the first embodiment. The first power supply 51 has a positive electrode connected to the first electrode 41 and a negative electrode connected to the third electrode 43, and applies a voltage V1. The first power supply 51 applies a voltage between both surfaces of the electrolyte membrane 2. The second power supply 52 is connected in series to the negative electrode of the first power supply 51, so that the positive electrode is connected to the third electrode 43, and the negative electrode is connected to the second electrode 42B. The second power supply 52 applies a voltage V2 to form a lower potential in the Li recovery aqueous solution RS than the back surface of the electrolyte membrane 2, thereby suppressing the development of electronic conductivity in the electrolyte membrane 2.

[0071] (Lithium recovery method) A lithium recovery method according to a second embodiment of the present invention will be described with reference to Fig. 6. The lithium recovery method according to this embodiment is performed by a lithium recovery apparatus 1B as follows. Note that in Fig. 6, a water supply device 81 and circulation devices 82 and 83 are omitted.

[0072] In this embodiment, the first power source 51 applies a voltage V1, and the second power source 52 applies a voltage V2 simultaneously. In the lithium recovery apparatus 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 FIG. 5). The power source 5B applies a positive voltage (V1+V2) to the first electrode 41 with respect to the second electrode 42B. Then, the same reactions as those in the first embodiment (see FIG. 2) occur in the aqueous solution S1 in the first electrode chamber 11 and the Li-containing non-aqueous solution FS in the Li supply chamber 12. That is, in the aqueous solution S1, a reaction represented by the following formula (1) or (5) occurs near the first electrode 41 to generate O2, and as a result, H2O in the aqueous solution S1 is converted into H2O. + The reaction of the following formula (6) occurs, in which Li passes through the ion exchange membrane 31 and moves to the Li-containing non-aqueous solution FS in the Li supply chamber 12. Then, in the Li-containing non-aqueous solution FS, Li + The reaction of the following formula (7), in which the ions migrate into the electrolyte membrane 2, occurs near the surface of the electrolyte membrane 2.

[0073] On the other hand, the following reaction occurs in the aqueous solution RS for Li recovery in the Li recovery chamber 13 where the second electrode 42B and the third electrode 43 are arranged. In the vicinity of the second electrode 42B, the application of a voltage (V1+V2) from the power source 5B causes H2O in the aqueous solution RS to convert electrons e - By supplying H and OH, the reaction of the following formula (4) occurs. - At the same time, the second power supply 52 applies a positive voltage V2 of a predetermined magnitude based on the voltage V1 to the second electrode 42B to the third electrode 43. Then, in the vicinity of the third electrode 43, the OH in the aqueous solution RS for recovering Li is generated. - The reaction of the following formula (1) occurs, and electrons e - is released to the third electrode 43, generating H2O and O2. This reaction is slower than the reaction of the following formula (4) in the vicinity of the second electrode 42B due to the difference in applied voltage. Therefore, in the aqueous solution RS for recovering Li, the reaction of the following formula (4) and the reaction of the following formula (1) are combined to produce OH - In response to this, in order to maintain the charge balance, Li in the electrolyte membrane 2 + The reaction of the following formula (3), in which H moves to the back surface of the electrolyte membrane 2, i.e., in the vicinity of the third electrode 43, occurs on the rear surface of the electrolyte membrane 2. In addition, in the Li recovery aqueous solution RS, H moves to the back surface of the electrolyte membrane 2 by the reaction of the following formula (4), in the vicinity of the second electrode 42B. + In order to resolve this, an imbalance in charge occurs due to the decrease in Li and the excess cations due to the reaction of the following formula (1) and the reaction of the following formula (3) near the third electrode 43. + The relative relationship between the magnitudes of the voltages V1 and V2 will be described later.

[0074] In this embodiment, application of the voltage V2 generates a potential gradient in the Li recovery aqueous solution RS, with the vicinity of the third electrode 43 (electrolyte membrane 2) being positive and the vicinity of the second electrode 42B being negative. Then, the electrons e supplied from the second electrode 42B to the Li recovery aqueous solution RS -moves from the third electrode 43 on the back surface of the electrolyte membrane 2 to the positive electrode of the second power source 52, and the potential of the third electrode 43, i.e., the back surface of the electrolyte membrane 2, is maintained high at approximately the O2 generating potential. The O2 generating potential is generated by the reduction of metal ions constituting the electrolyte membrane 2 (if the electrolyte membrane 2 is LLTO, 4+ +e - →Ti 3+ ) potential, the electrolyte membrane 2 generates electrons e - Therefore, the potential difference between both surfaces of the electrolyte membrane 2 can be set to a voltage equal to or greater than the applied voltage that causes the electrolyte membrane 2 to reach the reduction potential of at least one metal ion constituting the electrolyte membrane 2. In other words, when the voltage V1 that causes such a large potential difference is applied without applying the voltage V2, electrons e - However, in this embodiment, as described above, the application of the voltage V2 prevents the electrolyte membrane 2 from reaching the reduction potential of the metal ions, and the electrolyte membrane 2 absorbs electrons e - In addition, in the aqueous solution for recovering Li, the potential gradient + is attracted to the vicinity of the second electrode 42B and the Li + As a result, the Li concentration between both sides of the electrolyte membrane 2 decreases. + A large chemical potential difference occurs due to the concentration gradient, and Li between the lattice defect sites in the electrolyte membrane 2 + This will promote the movement of people.

[0075] Li in the electrolyte membrane 2 + As described in the first embodiment, the movement of Li in the electrolyte membrane 2 becomes faster as the potential gradient in the electrolyte membrane 2 becomes larger, that is, as the voltage V1 of the first power supply 51 becomes larger. + As described above, the movement of Li in the electrolyte membrane 2 + 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 higher the voltage V2 of the second power source 52, the easier the reaction of formula (3) becomes, and the faster the Li in the electrolyte membrane 2 +Furthermore, the higher the voltage V1, the greater the difference in reaction rate between the reaction of formula (4) and the reaction of formula (1) in the aqueous solution for Li recovery RS. - Since the rate of increase of the reaction rate of the formula (3) becomes high, the rate of increase of the reaction rate of the Li + can be transferred to the aqueous solution RS for Li recovery.

[0076] If the voltage V2 is not large enough relative to the required voltage determined by the voltage V1, a current flows from the third electrode 43 to the negative electrode of the first power supply 51, i.e., the third electrode 43 is charged with electrons e - , and a reaction represented by formula (4) occurs nearby, generating H2. As a result, electronic conductivity may be exhibited in the electrolyte membrane 2. Therefore, the voltage V2 is set to a value that prevents current from flowing from the third electrode 43 toward the negative electrode of the first power source 51. In theory, when the resistance between the first electrode 41 and the third electrode 43 is represented by R1, the resistance between the third electrode 43 and the second electrode 42B is represented by R2, the reaction resistance due to the reaction represented by formula (1) or (5) at the first electrode 41 is represented by Ra, and the reaction resistance due to the reaction represented by formula (4) at the second electrode 42B is represented by Rc, the voltages are set so that V2 ≥ V1 × [(R2 + Rc) / (R1 + Ra)] holds (see Patent Document 3). However, as the voltage V2 increases in this magnitude, the current flowing from the second power supply 52 to the third electrode 43 increases, and 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)) are accelerated by Li + Therefore, for example, an ammeter may be connected in series to the third electrode 43 (connecting the ammeter between the connection between the first power source 51 and the second power source 52 and the third electrode 43) and voltages V1 and V2 may be applied while measuring the current.

[0077] The lithium recovery device according to this embodiment can also accommodate a non-aqueous RSA solution for Li recovery (see FIG. 3) in the Li recovery chamber 13, as in the first embodiment. In this case, the electrodes 42B and 43 are formed of an electrode material that is stable even when a voltage is applied in the non-aqueous RSA solution for Li recovery. When voltages +V1 and +V2 are applied, the reaction of the following formula (9) occurs near the third electrode 43 in the non-aqueous RSA solution for Li recovery. + When the amount of dissolved salts such as HPF6 and HBF4 is small, the reaction of formula (1) and the reaction of formula (4) that generate O2 and H2 do not occur. Note that, since O2 is not generated near the third electrode 43, no current flows between the third electrode 43 and the positive electrode of the second power source 52. As described in the first embodiment, in the non-aqueous RSA solution for Li recovery, anions A n- Li + As a counter ion in the vicinity of the atom, charge neutrality is maintained and no change occurs.

[0078] (Modification) The lithium recovery device according to this embodiment may include an anion exchange membrane 32 as the first ion conductive membrane, as in the modification of the first embodiment (see FIG. 4). Furthermore, the lithium recovery device according to this embodiment may accommodate a non-aqueous solution RSA for Li recovery in the Li recovery chamber 13, and furthermore, can recover metallic lithium in the Li recovery chamber 13. For this purpose, the lithium recovery device 1B includes a second electrode 42A (see FIG. 3) instead of the second electrode 42B, and when voltages +V1 and +V2 are applied, the potential of the second electrode 42A is set to Li. + 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, so that the potential of the third electrode 43 is higher than the reduction potential of the metal ions.

[0079] According to the lithium recovery device of the second embodiment and its modified example, Li can be recovered from a non-aqueous solution in the same manner as in the first embodiment, and further, the amount of Li recovered per hour can be increased by increasing the applied voltage.

[0080] [Third embodiment] In the lithium recovery device according to the first embodiment, the treatment tank is divided by an ion exchange membrane into a Li supply chamber facing the electrolyte membrane and a first electrode chamber at the end, and a first electrode is placed in the first electrode chamber. + Ions other than Li move through the ion exchange membrane. + The lithium recovery chamber side can also be partitioned by an ion exchange membrane, and a second electrode can be placed in the end chamber. Hereinafter, a lithium recovery method according to a third embodiment of the present invention will be described.

[0081] 7 , a lithium recovery apparatus 1D according to a 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 treatment tank 7 partitioned into four chambers 11, 12, 13, and 14 in this order by membranes 31, 2, and 33, a first electrode 41 provided in a first electrode chamber (third chamber) 11 at one end of the treatment tank 7, a second electrode 42C provided in a chamber (fourth chamber) 14 at the other end, and a power source 5 connected between the electrodes 41 and 42C with the first electrode 41 as the positive electrode. The end chamber (fourth chamber) 14 of the treatment tank 7, which is separated from the Li recovery chamber (first chamber) 13 by the bipolar membrane 33, is a second electrode chamber and contains an aqueous solution S2. The first electrode chamber (third chamber) 11 contains an aqueous solution S1, the Li supply chamber (second chamber) 12 contains a Li-containing non-aqueous solution FS, and the Li recovery chamber (first chamber) 13 contains an aqueous solution RS for Li recovery. The lithium recovery apparatus 1D may further include water supply devices 81 and 84 for supplying water (aqueous solutions S1 and S2) to the chambers 11 and 14, respectively, and circulation devices 82 and 83 for the chambers 12 and 13, respectively, as necessary. The lithium recovery apparatus 1D may further include a heating device, a cooling device, a liquid level sensor, a pH meter, an exhaust means, and the like, similar to the lithium recovery apparatus 1 according to the first embodiment. The lithium recovery apparatus 1D according to this embodiment has a configuration similar to that of the lithium recovery apparatus 1 according to the first embodiment shown in FIG. 1 , in which a bipolar membrane 33 is added, a second electrode chamber 14 is added to the end of the treatment tank 7 on the Li recovery chamber 13 side, and a second electrode 42C is disposed in the second electrode chamber 14.

[0082] The aqueous solution S2 is a cation recovery aqueous solution that receives cations in the Li recovery aqueous solution RS in the Li recovery chamber 13, and / or an anion supply aqueous solution that supplies anions to the Li recovery aqueous solution RS. The ions exchanged in the aqueous solution S2 are based on ions that permeate the second ion conductive membrane 33. The aqueous solution S2 is, like the aqueous solution S1, pure water, for example, at the start of operation of the lithium recovery device 1D. Alternatively, the aqueous solution S2 may contain ions (H + and / or OH - In order to smoothly transfer the electrolyte (including the electrolytes) to the aqueous solution S2, the aqueous solution S2 may be an acidic, neutral, or alkaline aqueous solution (electrolyte aqueous solution) having a relatively high electronic conductivity. After the start of operation, it is preferable that the aqueous solution S2 does not have a higher pH than the aqueous solution S1 in the first electrode chamber 11 (S1<S2), and it is more preferable that the aqueous solution S2 has a lower pH. To achieve this, it is preferable to use the same aqueous solution for the aqueous solutions S1 and S2, or to use a combination of aqueous solutions in which the aqueous solution S1 has a higher pH than the aqueous solution S2, for example, a neutral aqueous solution S1 and an acidic aqueous solution S2.

[0083] The second ion conductive membrane 33 is provided to separate the treatment tank 7 into the Li recovery chamber 13 and the second electrode chamber 14. + The Li contained in the aqueous solution RS for Li recovery and the aqueous solution S2 is not conducted. + The second ion conductive membrane 33 selectively conducts at least one type of ion other than H. + a proton conducting membrane that conducts H + and OH - A bipolar water splitting membrane that conducts ions can be used, and in this embodiment, a bipolar water splitting membrane is used. The bipolar membrane 33 is disposed with the anion exchange membrane facing the first electrode 41 (left side in FIG. 7 ). The second ion conductive membrane 33 is disposed at a sufficient distance from the electrolyte membrane 2, but preferably the distance between them is not too great. The second ion conductive membrane 33 corresponds to the pH of the aqueous solution RS for Li recovery and the pH of the aqueous solution S2, including after the start of operation. As with the first ion conductive membrane 31, a known second ion conductive membrane can be used for the second ion conductive membrane 33.

[0084] As shown in FIG. 7 , the second electrode 42C can be disposed in the second electrode chamber 14 at a distance from the bipolar membrane 33, allowing the aqueous solution S2 to contact the entire surface of the bipolar membrane 33. On the other hand, the distance between the second electrode 42C and the bipolar membrane 33 is preferably short so that the distance between the first electrode 41 and the second electrode 42C is not excessively large. The second electrode 42C is also preferably disposed parallel to the electrolyte membrane 2. The second electrode 42C is formed of an electrode material that is electronically conductive and stable in the aqueous solution S2 even when a voltage is applied. The material preferably has catalytic activity for the reaction represented by the following formula (4). The remaining configuration of the second electrode 42C is the same as that of the second electrode 42B of the second embodiment.

[0085] The water supply device 81 and the circulation devices 82, 83 can be configured in the same manner as in the first embodiment. In this embodiment, in particular, in order to shorten the gap 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 not long, that is, the volume of the Li recovery chamber 13 is not large, similar to the Li supply chamber 12. By circulating a large amount of Li recovery aqueous solution RS relative to the volume of the Li recovery chamber 13 using the circulation device 83, the Li content of the Li recovery aqueous solution RS can be reduced. + This makes it possible to suppress the pH of the aqueous solution RS for recovering Li from increasing, and to prevent the Li between both surfaces of the electrolyte membrane 2 from increasing. + It is possible to suppress the decrease in chemical potential difference due to the concentration gradient.

[0086] The water supply device 84 is a device that supplies water to the second electrode chamber 14, and replenishes the water that is lost in the aqueous solution S2 during operation due to the reaction of formula (4). Like the water supply device 81, the water supply device 84 may supply pure water, or may supply the aqueous solution S2 or an ionic compound, and can adjust the pH and conductivity of the aqueous solution S2.

[0087] (Lithium recovery method) A lithium recovery method according to a third embodiment of the present invention will be described with reference to Fig. 8. The lithium recovery method according to this embodiment is performed by a lithium recovery apparatus 1D as follows. Note that water supply devices 81 and 84 and circulation devices 82 and 83 are omitted from Fig. 8.

[0088] In this embodiment, similarly to the first embodiment, the power supply 5 applies a positive voltage V1 (+V1) to the first electrode 41 relative to the second electrode 42C. The reactions caused by the application of the voltage +V1 in the aqueous solution S1 in the first electrode chamber 11 and in the Li-containing non-aqueous solution FS in the Li supply chamber 12 are similar to those in the first embodiment. That is, in the aqueous solution S1, a reaction represented by the following formula (1) or (5) occurs near the first electrode 41 to generate O2, and as a result, H2O in the aqueous solution S1 is converted into + The reaction of the following formula (6) occurs, in which Li passes through the ion exchange membrane 31 and moves to the Li-containing non-aqueous solution FS in the Li supply chamber 12. Then, in the Li-containing non-aqueous solution FS, Li + The reaction of the following formula (7), in which the ions migrate into the electrolyte membrane 2, occurs near the surface of the electrolyte membrane 2.

[0089] On the other hand, in the aqueous solution S2 in the second electrode chamber 14 where the second electrode 42C is disposed, the following reaction occurs when a voltage +V1 is applied: H2O in the aqueous solution S2 loses electrons e - By supplying H and OH, the reaction of the following formula (4) occurs. - Generates OH - As the charge increases, the OH - permeates the bipolar membrane 33 and moves to the aqueous solution RS for Li recovery in the Li recovery chamber 13, and at the same time, H of the HO in the aqueous solution RS for Li recovery + passes through the bipolar membrane 33 and moves to the aqueous solution S2. + reduction of OH - In order to maintain the charge balance, the Li in the electrolyte membrane 2 is added to the aqueous solution RS for Li recovery. +In the Li recovery aqueous solution RS, the application of a voltage +V1 generates an electric field in the direction from the electrolyte membrane 2 side to the bipolar membrane 33 side, and Li + are moved away from the vicinity of the back surface of the electrolyte membrane 2 by electrostatic attraction.

[0090] In the lithium recovery method according to this embodiment, as in the first embodiment, by setting the voltage V1 to be equal to or higher than the electrolysis voltage, the reaction of formula (1) or formula (5) and the reaction of formula (4) occur, resulting in Li + moves through the electrolyte membrane 2. In the present embodiment, the second electrode 42C is in contact with the aqueous solution S2 in the second electrode chamber 14, and therefore the electrolysis voltage can be easily controlled and the applied voltage V1 can be suppressed by maintaining the liquid volume and concentration of the aqueous solution S2 using the water supply device 84 so that the pH does not fluctuate during operation.

[0091] (Modification) The lithium recovery apparatus 1D according to this embodiment can use an anion exchange membrane 32 as the first ion conductive membrane, similar to the lithium recovery apparatus 1C according to the modification of the first embodiment (see FIG. 4). The lithium recovery apparatus 1D can also use an anion exchange membrane as the second ion conductive membrane. As with the anion exchange membrane 32, a known anion exchange membrane can be used as the second ion conductive membrane. In this case, the aqueous solution S2 can be used when the OH - Anions other than (e.g., Cl - ), this anion becomes OH - The OH is transferred to the aqueous solution for Li recovery RS. - When the inclusion of anions other than OH is undesirable and an anion exchange membrane is used as the second ion conductive membrane, the aqueous solution S2 - Alternatively, a monovalent anion-selective permeable ion exchange membrane that allows only monovalent anions to pass through is applied to the second ion conductive membrane, and the aqueous solution S2 contains no anions other than OH. - For anions other than those mentioned above, ions with a valence of 2 or more (e.g., SO4 2- ) may be contained only.

[0092] The lithium recovery device according to this embodiment can accommodate a non-aqueous solution RSA for Li recovery in the Li recovery chamber 13, as in the modified example of the first embodiment. The lithium recovery device 1E according to this modified example includes an anion exchange membrane 34 as the second ion conductive membrane, as shown in FIG. 9. In this modified example, the aqueous solution S2 contains BF4 - and the like, which are water-soluble and can recover Li in non-aqueous RSA for Li recovery. + Anion A, which is the counter ion of n- The anion exchange membrane 34 contains the anion A n- A known membrane can be applied as the first ion-conductive membrane, similar to the anion exchange membrane 32. The lithium recovery device 1E may be provided with the anion exchange membrane 32 as the first ion-conductive membrane (see FIG. 4).

[0093] The lithium recovery method using the lithium recovery device 1E is the same as the method using the lithium recovery device 1D according to the previous embodiment (see FIG. 8). In this modification, as shown in FIG. 9, the application of a voltage +V1 causes the anions A n- permeates the anion exchange membrane 34 and moves to the non-aqueous solution for Li recovery, and in the non-aqueous solution for Li recovery, the Li in the electrolyte membrane 2 is + is moving.

[0094] In this modified example, as the operation time progresses, the aqueous solution S2 not only loses water due to the reaction of formula (4), but also loses anions A n- Therefore, the pH of the aqueous solution S2 may be adjusted during operation as needed.

[0095] The lithium recovery device 1E may include a bipolar membrane for water splitting or a proton conductive membrane as the second ion conductive membrane (see FIG. 8). In this case, in the non-aqueous solution for Li recovery, H + moves to the aqueous solution S2, and the Li in the electrolyte membrane 2 + Therefore, the non-aqueous RSA for Li recovery is + Ensure that the salts of HPF6 and HBF4 are fully dissolved, and if necessary, add H during operation. + A salt of the formula (I) may be added.

[0096] According to the lithium recovery device of the third embodiment and its modified example, Li can be recovered from a non-aqueous solution as in the first embodiment, and further, power consumption can be reduced because the electrolysis voltage can be easily controlled. Furthermore, since the electrodes do not come into contact with the Li recovery solution, there is no risk of the electrode material being contaminated in the Li recovery solution, particularly when Li is recovered in an organic solvent (non-aqueous solution for Li recovery).

[0097] [Fourth embodiment] The lithium recovery device according to the third embodiment is provided with two power sources and the voltages of each are set to appropriate values, as in the second embodiment, thereby making it possible to increase the amount of Li recovered per hour. Hereinafter, a lithium recovery device and a lithium recovery method according to the fourth embodiment of the present invention will be described.

[0098] (Lithium Recovery Apparatus) As shown in FIG. 10 , a lithium recovery apparatus 1F according to a 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 treatment tank 7 partitioned into four chambers 11, 12, 13, and 14 in this order by membranes 31, 2, and 33, a first electrode 41 provided in a first electrode chamber (third chamber) 11 at one end of the treatment tank 7, a second electrode 42C provided in a second electrode chamber (fourth chamber) 14, a third electrode 43 provided in contact with the electrolyte membrane 2 in a Li recovery chamber (first chamber) 13, and a power source 5B connected between the electrodes 41 and 42C, with the first electrode 41 being positive. The power source 5B includes a first power source 51 and a second power source 52 connected in series to the negative electrode of the first power source 51, and the third electrode is connected to the negative electrode of the first power source 51. The first electrode chamber (third chamber) 11 contains an aqueous solution S1, the Li supply chamber (second chamber) 12 contains a Li-containing non-aqueous solution FS, the Li recovery chamber (first chamber) 13 contains a Li recovery aqueous solution RS, and the second electrode chamber (fourth chamber) 14 contains an aqueous solution S2. The lithium recovery apparatus 1F may further include water supply devices 81, 84 and circulation devices 82, 83, as necessary. The lithium recovery apparatus 1F may further include a heating device, a cooling device, a liquid level sensor, a pH meter, an exhaust means, and the like, similar to the lithium recovery apparatus 1 according to the first embodiment. The lithium recovery apparatus 1F according to this embodiment has a configuration similar to the lithium recovery apparatus 1D according to the third embodiment (see FIG. 7), except that a bipolar membrane 33 is added to the lithium recovery apparatus 1B according to the second embodiment (see FIG. 5), a second electrode chamber 14 is added to the end of the treatment tank 7, and a second electrode 42C is disposed in the second electrode chamber 14.

[0099] Each element of the lithium recovery apparatus 1F according to this embodiment can be configured similarly to the elements of the lithium recovery apparatuses 1B and 1D according to the second and third embodiments. In the lithium recovery apparatus 1F, the second electrode 42C is an electrode for forming a lower potential than the rear surface of the electrolyte membrane 2 in the aqueous Li recovery solution RS in the Li recovery chamber 13, similar to the second electrode 42B in the second embodiment.

[0100] (Lithium recovery method) A lithium recovery method according to a fourth embodiment of the present invention will be described with reference to Fig. 11. The lithium recovery method according to this embodiment is performed by a lithium recovery apparatus 1F as follows. Note that water supply devices 81 and 84 and circulation devices 82 and 83 are omitted from Fig. 11.

[0101] In this embodiment, similarly to the second embodiment (see FIG. 6), the first power supply 51 applies a voltage V1 and the second power supply 52 applies a voltage V2 simultaneously. That is, the first power supply 51 and the second power supply 52 (power supply 5B, see FIG. 10) connected in series apply a positive voltage (V1+V2) to the first electrode 41 with respect to the second electrode 42C. Then, the same reactions as those in the first embodiment (see FIG. 2) and the second embodiment occur in the aqueous solution S1 in the first electrode chamber 11 and the Li-containing non-aqueous solution FS in the Li supply chamber 12. That is, in the aqueous solution S1, a reaction represented by the following formula (1) or (5) occurs near the first electrode 41 to generate O2, and as a result, H2O in the aqueous solution S1 is converted into O2. + The reaction of the following formula (6) occurs, in which Li passes through the ion exchange membrane 31 and moves to the Li-containing non-aqueous solution FS in the Li supply chamber 12. Then, in the Li-containing non-aqueous solution FS, Li + The reaction of the following formula (7), in which the ions migrate into the electrolyte membrane 2, occurs near the surface of the electrolyte membrane 2.

[0102] In the aqueous solution S2 in the second electrode chamber 14 in which the second electrode 42C is disposed, a reaction similar to that in the third embodiment (FIG. 8) occurs. That is, when a voltage (V1+V2) is applied, a reaction represented by the following formula (4) occurs near the second electrode 42C, and H and OH are reacted. - On the other hand, in the aqueous solution RS for Li recovery in the Li recovery chamber 13 in which the third electrode 43 is disposed, the OH in the aqueous solution RS for Li recovery is generated in the vicinity of the third electrode 43 by applying the voltage V2, as in the second embodiment. - The reaction of the following formula (1) occurs to generate H2O and O2. As in the second embodiment, this reaction is slower than the reaction of the following formula (4) in the vicinity of the second electrode 42C (aqueous solution S2). Therefore, in order to maintain the charge balance between the aqueous solutions S2 and RS, the OH of the aqueous solution S2 is -passes through the bipolar membrane 33 and moves to the aqueous solution RS for Li recovery, and at the same time, H + The lithium in the electrolyte membrane 2 is further absorbed in the aqueous solution RS for recovering lithium by the bipolar membrane 33. + The reaction of the following formula (3) occurs.

[0103] In this embodiment, as in the second embodiment, application of the voltage V2 generates a potential gradient in the aqueous solution RS for Li recovery, and the potential on the back surface of the electrolyte membrane 2 is maintained high at approximately the O2 generation potential, and the electrolyte membrane 2 generates electrons e - In addition, due to this potential gradient, the Li + Therefore, the potential difference (voltage V1) between both sides of the electrolyte membrane 2 is increased to + can be transferred at high speed to the aqueous solution RS for recovering Li. The relative relationship between the magnitudes of the voltages V1 and V2 is as described in the second embodiment.

[0104] (Modification) The lithium recovery apparatus 1F according to this embodiment can employ an anion exchange membrane 32 as the first ion conductive membrane, similar to the lithium recovery apparatus 1C according to the modification of the first embodiment (see FIG. 4). The lithium recovery apparatus 1F can employ an anion exchange membrane as the second ion conductive membrane, similar to the lithium recovery apparatus according to the third embodiment. The lithium recovery apparatus 1F can accommodate a non-aqueous solution RSA for Li recovery in the Li recovery chamber 13, similar to the lithium recovery apparatus 1E according to the modification of the third embodiment (see FIG. 9).

[0105] According to the lithium recovery device of the fourth embodiment and its modified example, as in the second embodiment, the applied voltage can be increased to increase the amount of Li recovered per unit time from a non-aqueous solution, and further, power consumption can be reduced as in the third embodiment.

[0106] [Fifth embodiment] In the lithium recovery device 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 into which a Li-containing non-aqueous solution is introduced and a H +The lithium recovery method according to the fifth embodiment of the present invention will be described below.

[0107] (Lithium Recovery Apparatus) A lithium recovery apparatus (hereinafter, referred to as the lithium recovery apparatus according to the fifth embodiment) used in the lithium recovery method according to the fifth embodiment of the present invention will be described. As shown in Fig. 12, the lithium recovery apparatus 1G according to the fifth embodiment includes an electrolyte membrane (lithium ion conductive electrolyte membrane) 2, a treatment tank 7 partitioned by the electrolyte membrane 2 into a chamber (second chamber) 12 and a chamber (first chamber) 13, electrodes 41A and 42B provided in each of the chambers 12 and 13, and a power source 5 connected between the electrodes 41A and 42B with the chamber (second chamber) 12 side, i.e., the electrode 41A, being positive. The chamber (second chamber) 12 is a Li supply chamber that contains a Li-containing non-aqueous solution FS and also contains water (HO). The chamber (first chamber) 13 is a Li recovery chamber that contains a Li recovery aqueous solution RS. The lithium recovery apparatus 1G may further include, as necessary, water supply devices 81, 84 that supply water to the chambers 12, 13, and an agitator 8 that agitates the Li-containing non-aqueous solution FS and water (HO) in the chambers 12, 13. The lithium recovery apparatus 1G may further include a heating device, a cooling device, a liquid level sensor, a pH meter, an exhaust means, and the like, similar to the lithium recovery apparatus 1 according to the first embodiment. The lithium recovery apparatus 1G according to this embodiment has a similar structure to the apparatus 101 shown in FIG. 25 that recovers Li from a Li-containing aqueous solution such as seawater.

[0108] The Li-containing non-aqueous solution FS can be a non-aqueous solution similar to that in the first and second embodiments, and may be a water-soluble organic solvent (e.g., EC) or a poorly soluble or insoluble organic solvent (e.g., EMC). The water contained in the Li supply chamber 12 together with the Li-containing non-aqueous solution FS may be pure water, or an acidic, neutral, or alkaline aqueous solution, as in the aqueous solution S1 of the first embodiment. In the Li supply chamber 12, water (HO) containing H + The total number of valences of the cations to be transferred from the Li-containing non-aqueous solution FS to the aqueous solution for Li recovery RS is +On the other hand, if the amount of water in the Li supply chamber 12 is excessive relative to the amount of Li-containing non-aqueous solution FS, the amount of Li in the Li-containing non-aqueous solution FS may be increased. + Li in contact with the electrolyte membrane 2 relative to the concentration + becomes less, Li + Specifically, at the start of operation of the lithium recovery apparatus 1G, the amount of the Li-containing non-aqueous solution FS and the amount of Li + The amount of water stored may correspond to the concentration, or water may be replenished into the Li supply chamber 12 by the water supply device 81 during operation. As in the first embodiment, the aqueous solution for Li recovery RS is preferably pure water or an aqueous LiOH solution at the start of operation of the lithium recovery apparatus 1G.

[0109] The first electrode 41A and the second electrode 42B are electrodes for applying a voltage between both surfaces of the electrolyte membrane 2, causing a potential difference on the Li recovery chamber 13 side to be lower. To this end, the electrodes 41A and 42B are provided in each of the chambers 12 and 13 of the treatment tank 7. The first electrode 41A and the second electrode 42B are provided in contact with the electrolyte membrane 2 or spaced apart and facing each other, and are preferably arranged 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 spaced apart from the electrolyte membrane 2, and it is even more preferable that one is in contact with the electrolyte membrane 2 and the other is spaced apart. In FIG. 12 , the first electrode 41A is in contact with the electrolyte membrane 2, and the second electrode 42B is spaced apart. The second electrode 42B can have a configuration similar to that of the second embodiment.

[0110] As described above, the first electrode 41A is provided in contact with the electrolyte membrane 2. The first electrode 41A preferably has dimensions that allow a voltage to be applied to a wider area of ​​the electrolyte membrane 2. On the other hand, the first electrode 41A preferably has a porous structure, such as a mesh structure, so that the Li-containing non-aqueous solution FS can contact a sufficient area of ​​the surface of the electrolyte membrane 2 and be continuously replaced. Similarly to the second electrode 42 of the first embodiment, the first electrode 41A may be formed directly on one side of the electrolyte membrane 2, or may be fixed to the treatment tank 7 with a jig so as to be in contact with the electrolyte membrane 2. The first electrode 41A is formed of an electrode material that is stable in the Li-containing non-aqueous solution FS and water even when a voltage is applied. Similarly to the first electrode 41 of the first embodiment, the first electrode 41A is formed of a material that is electronically conductive and preferably has catalytic activity for the reaction of the following formula (1) or (5). Furthermore, the first electrode 41A is preferably made of a material that can be easily processed into the above-described shape.

[0111] In the lithium recovery apparatus 1G, the water supply device 81 supplies water to the Li supply chamber 12, and the water supply device 84 supplies water to the Li recovery chamber 13. During operation, water is reduced in the mixed solution FS+HO in the Li supply chamber 12 due to the reaction of formula (1) or formula (5), and the water supply device 81 replenishes this water. Similarly, during operation, water is reduced in the aqueous solution for Li recovery RS due to the reaction of formula (4), and the water supply device 84 replenishes this water.

[0112] The agitator 8 includes a screw and a motor for rotating the screw, and a known agitator can be used. The agitator 8 provided in the Li supply chamber 12 agitates the Li-containing non-aqueous solution FS and water within the Li supply chamber 12 and circulates the mixed solution FS+HO in contact with the electrolyte membrane 2 and the first electrode 41A so that the two solutions are continuously replaced. In particular, when the organic solvent in the Li-containing non-aqueous solution FS is poorly soluble or insoluble in water, it is preferable to continuously agitate the mixed solution FS+HO during operation of the lithium recovery apparatus 1G. Alternatively, as in the sixth embodiment described later (see FIG. 15 ), a circulation device 82 may be provided to circulate the mixed solution FS+HO between the Li supply chamber 12 and outside the treatment tank 7 while stirring. The agitator 8 provided in the Li recovery chamber 13 agitates the aqueous Li recovery solution RS in contact with the electrolyte membrane 2 and the second electrode 42B within the Li recovery chamber 13 so that the aqueous Li recovery solution RS is continuously replaced. Alternatively, a circulation device 83 may be provided as in the first embodiment (see FIG. 1).

[0113] (Lithium recovery method) A lithium recovery method according to a fifth embodiment of the present invention will be described with reference to Fig. 13. The lithium recovery method according to this embodiment is performed by a lithium recovery apparatus 1G as follows. Note that in Fig. 13, the agitator 8 and water supply devices 81 and 84 are omitted.

[0114] In the lithium recovery device 1G, as in the first embodiment, the power supply 5 applies a positive voltage V1 (+V1) to the first electrode 41A relative to the second electrode 42B. The application of the voltage +V1 causes the following reaction in the mixed solution FS+H2O of the Li-containing non-aqueous solution FS and water in the Li supply chamber 12. Here, the reaction will be described in the case where the Li-containing non-aqueous solution FS is insoluble in water and the mixed solution FS+H2O is separated into an aqueous phase and an organic solvent phase (non-aqueous phase). As in the first embodiment (see FIG. 2), OH in the water (H2O) reacts with the Li-containing non-aqueous solution FS in the vicinity of the first electrode 41A. - The reaction of the following formula (1) occurs, generating H2O and O2, and electrons e - Alternatively, water (HO) undergoes the reaction of the following formula (5), + and O2 are generated, and electrons e - In the mixture of water (H2O), OH -decreases or H + As the amount of H in HO increases, in order to maintain the charge balance, the amount of H in HO increases near the interface with the Li-containing non-aqueous solution FS. + The reaction of the following formula (6) occurs, in which the water in the Li supply chamber 12 is an aqueous solution containing metal ions, and the metal ions may also migrate to the Li-containing non-aqueous solution FS. In addition, the Li-containing non-aqueous solution FS may contain water-soluble anions A. n- When containing an anion A n- In the mixed solution of Li-containing non-aqueous solution FS, H + and other cations, or even anions A n- As a result of the decrease in the amount of Li in the Li-containing non-aqueous solution, in order to maintain the charge balance, + The reaction of the following formula (7), in which the ions migrate into the electrolyte membrane 2, occurs near the surface of the electrolyte membrane 2.

[0115] In addition, when the Li-containing non-aqueous solution FS is soluble in water and the mixed solution FS + HO is one phase, even if the water in the Li supply chamber 12 is pure water or an alkaline aqueous solution, the reaction of formula (5) occurs near the first electrode 41A, and the reactions of formula (6) and formula (11) are omitted, and the reaction of formula (7) occurs.

[0116] On the other hand, in the aqueous solution RS for Li recovery in the Li recovery chamber 13, the application of the voltage +V1 causes the reactions of the following formulas (4) and (3) to occur in the same manner as in the first embodiment, generating H in the vicinity of the second electrode 42B, and Li in the electrolyte membrane 2 + moves to the aqueous solution RS for recovering Li.

[0117] After the operation is completed, Li can be recovered from the aqueous Li recovery solution RS in the Li recovery chamber 13 and the circulation chamber of the circulation device 83 in the same manner as in the first embodiment. On the other hand, Li can be recovered from the mixed solution of the Li-containing non-aqueous solution FS and water in the Li supply chamber 12 and the circulation tank of the circulation device 82 in the same manner as in the first embodiment. + Metal ions other than M n+ The organic solvent can be recovered by a known method appropriate for each of them.

[0118] In the lithium recovery method according to this embodiment, in order to reuse the organic solvent of the Li-containing non-aqueous solution, which is the Li source, a treatment for separating it from water after the end of operation is required. On the other hand, since an ion exchange membrane is not required, the structure of the lithium recovery device is simpler, and Li can be recovered even when an ion exchange membrane resistant to organic solvents is difficult to obtain depending on the organic solvent of the Li-containing non-aqueous solution. In addition, H contained in water can be easily recovered. + Furthermore, when other cations move into the Li-containing non-aqueous solution (organic solvent), no energy is required to pass through the ion exchange membrane, thereby reducing power consumption.

[0119] (Modification) As in the first embodiment, the lithium recovery device according to this embodiment can also accommodate a non-aqueous RSA solution for Li recovery (see FIG. 3) in the Li recovery chamber 13. In this case, the second electrode 42B is formed of an electrode material that is stable in the non-aqueous RSA solution for Li recovery even when a voltage is applied. Furthermore, as in the modification of the first embodiment (see FIG. 3), a second electrode 42A is provided instead of the second electrode 42B, and metallic lithium can be recovered by depositing it on the surface of the second electrode 42A (see FIG. 3).

[0120] 14 , a lithium recovery apparatus 1H used in a lithium recovery method according to a modified fifth embodiment of the present invention (hereinafter referred to as a lithium recovery apparatus according to the modified fifth embodiment) includes an electrolyte membrane (lithium ion conductive electrolyte membrane) 2, a treatment tank 7 partitioned into two chambers 12 and 13 by the electrolyte membrane 2, an electrode 41 provided in the Li supply chamber (second chamber) 12, a third electrode 43 provided in contact with the electrolyte membrane 2 in the Li recovery chamber (first chamber) 13, and a second electrode 42B provided spaced apart from the third electrode 43. Between the electrodes 41 and 42B, a first power source 51 is connected with the first electrode 41 as a positive electrode, and a second power source 52 is connected in series with the negative electrode of the first power source 51, and the third electrode 43 is connected to the negative electrode of the first power source 51. As in the previous embodiment, the Li supply chamber 12 contains a Li-containing non-aqueous solution FS and water (HO), and the Li recovery chamber 13 contains a Li recovery aqueous solution RS. The lithium recovery apparatus 1H may further include a stirrer 8 and water supply devices 81 and 84 as necessary (see FIG. 12). The elements of the lithium recovery apparatus 1H according to this modification can be configured similarly to the elements of the lithium recovery apparatuses 1B and 1G according to the second and fifth embodiments.

[0121] In the lithium recovery method according to this modification using the lithium recovery apparatus 1H, as in the second embodiment (see FIG. 6), as shown in FIG. 14, a voltage V1 is applied by a first power source 51 and a voltage V2 is applied by a second power source 52 simultaneously. The reaction in the mixed solution FS+HO of the Li-containing non-aqueous solution FS and water in the Li supply chamber 12 is the same as in the previous embodiment (see FIG. 13). On the other hand, the reaction in the aqueous solution RS for Li recovery in the Li recovery chamber 13 is the same as in the second embodiment. The relative relationship between the magnitudes of the voltages V1 and V2 is as described in the second embodiment.

[0122] The lithium recovery device according to this modification can also accommodate a non-aqueous solution RSA for Li recovery (see FIG. 3) in the Li recovery chamber 13, similarly to the second embodiment.

[0123] According to the lithium recovery method of the fifth embodiment and its modified example, Li can be recovered from a non-aqueous solution in the same manner as in the first embodiment by using a lithium recovery device (see FIG. 25) having a simple structure similar to that of the conventional device.

[0124] Sixth Embodiment In the lithium recovery device according to the fifth embodiment, the Li recovery chamber side of the treatment tank can also be partitioned with an ion exchange membrane, and a second electrode chamber can be provided as in the third embodiment. Hereinafter, a lithium recovery method according to the sixth embodiment of the present invention will be described.

[0125] 15 , a lithium recovery apparatus 1J according to a 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 treatment tank 7 partitioned into three chambers 12, 13, and 14 by the electrolyte membrane 2 and the bipolar membrane 33, a first electrode 41A provided in the chamber (second chamber) 12 at one end of the treatment tank 7, a second electrode 42C provided in the chamber (third chamber) 14 at the other end, and a power source 5 connected between the electrodes 41A and 42C with the first electrode 41A as the positive electrode. The chamber (second chamber) 12 at the end of the treatment tank 7, partitioned by the electrolyte membrane 2, is a Li supply chamber containing a Li-containing non-aqueous solution FS and also containing water (HO). The central chamber (first chamber) 13 is a Li recovery chamber containing a Li recovery aqueous solution RS. The end chamber (third chamber) 14 separated by the bipolar membrane 33 is a second electrode chamber and contains the aqueous solution S2. The lithium recovery apparatus 1J may further include circulation devices 82, 83 and a water supply device 84 as necessary. The lithium recovery apparatus 1J may further include a heating device, a cooling device, a liquid level sensor, a pH meter, an exhaust means, and the like, similar to the lithium recovery apparatus 1 according to the first embodiment. The lithium recovery apparatus 1J according to this embodiment has a configuration in which a bipolar membrane 33 is added to the lithium recovery apparatus 1G according to the fifth embodiment shown in FIG. 12 , a second electrode chamber 14 is added to the end of the treatment tank 7 on the Li recovery chamber 13 side, and a second electrode 42C is disposed in this second electrode chamber 14.

[0126] The components of the lithium recovery apparatus 1J according to this embodiment can be configured similarly to the components of the lithium recovery apparatuses 1D and 1G according to the third and fifth embodiments. In the lithium recovery apparatus 1J, the circulation device 82 circulates the mixed solution FS+HO between the Li supply chamber 12 and outside the treatment tank 7 while stirring it, and further replenishes water lost due to the reaction of formula (1) or formula (5). Alternatively, the lithium recovery apparatus 1J may include a stirrer 8 and a water supply device 81, as in the lithium recovery apparatus 1G according to the fifth embodiment. Furthermore, it is preferable that the aqueous solution S2 does not have a high pH relative to the mixed solution FS+HO in the Li supply chamber 12 or the water (aqueous solution) therein, and it is even more preferable that the aqueous solution S2 have a lower pH.

[0127] (Lithium recovery method) A lithium recovery method according to a sixth embodiment of the present invention will be described with reference to Fig. 16. The lithium recovery method according to this embodiment is performed by a lithium recovery apparatus 1J as follows. Note that in Fig. 16, circulation devices 82 and 83 and a water supply device 84 are omitted.

[0128] In the lithium recovery method according to the sixth embodiment of the present invention, as in the first embodiment, the power source 5 applies a positive voltage V1 (+V1) to the first electrode 41A relative to the second electrode 42C. The reaction in the mixed solution FS+HO of the Li-containing non-aqueous solution FS and water in the Li supply chamber 12 is the same as in the fifth embodiment (see FIG. 13). Meanwhile, the reactions in the aqueous solution for Li recovery 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 (see FIG. 8).

[0129] (Modification) In the lithium recovery device according to this embodiment, an anion exchange membrane can be applied to the second ion conductive membrane, as in the third embodiment. Furthermore, by applying an anion exchange membrane to the second ion conductive membrane, a non-aqueous RSA solution for Li recovery can be accommodated in the Li recovery chamber 13, as in the modification of the third embodiment (see FIG. 9 ).

[0130] 17 , the lithium recovery device according to the present embodiment includes an electrolyte membrane (lithium ion conductive electrolyte membrane) 2, a bipolar membrane (second ion conductive membrane) 33, a treatment tank 7 partitioned into three chambers 12, 13, and 14 in this order by the electrolyte membrane 2 and the bipolar membrane 33, a first electrode 41 provided in the Li supply chamber (second chamber) 12, a second electrode 42C provided in the second electrode chamber (third chamber) 14, a third electrode 43 provided in the Li recovery chamber (first chamber) 13 in contact with the electrolyte membrane 2, and a first power source 51 connected between the electrodes 41 and 42C, with the first electrode 41 as the positive electrode, and a second power source 52 connected in series to the negative electrode of the first power source 51, with the third electrode 43 connected to the negative electrode of the first power source 51. As in the previous embodiment, the Li supply chamber 12 contains a Li-containing non-aqueous solution FS and water (HO), the Li recovery chamber 13 contains a Li recovery aqueous solution RS, and the second electrode chamber 14 contains an aqueous solution S2. The lithium recovery apparatus 1K may further include circulation devices 82 and 83 and a water supply device 84, as necessary (see FIG. 15 ). The elements of the lithium recovery apparatus 1K according to this modification can be configured similarly to the elements of the lithium recovery apparatuses 1F and 1J according to the fourth and sixth embodiments (see FIGS. 10 and 15 ).

[0131] In the lithium recovery method according to this modification using the lithium recovery apparatus 1K, as in the second embodiment (see FIG. 6), as shown in FIG. 17, a voltage V1 is applied by a first power source 51 and a voltage V2 is applied by a second power source 52 simultaneously. The reaction in the mixed solution FS+HO of the Li-containing non-aqueous solution FS and water in the Li supply chamber 12 is the same as in the fifth embodiment (see FIG. 13). Meanwhile, the reactions in the aqueous solution RS for Li recovery 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 (see FIG. 11). The relative relationship between the magnitudes of the voltages V1 and V2 is as described in the second embodiment.

[0132] In the lithium recovery device 1K of this modified example, as in the lithium recovery device of the above embodiment, an anion exchange membrane can be applied to the second ion conductive membrane, and further, by applying an anion exchange membrane to the second ion conductive membrane, a non-aqueous solution RSA for Li recovery can be stored in the Li recovery chamber 13.

[0133] According to the lithium recovery method of the sixth embodiment and its modified example, as in the third embodiment, Li can be recovered from a non-aqueous solution, the electrolysis voltage can be easily controlled to reduce power consumption, and further, a lithium recovery device with a relatively simple structure can be provided.

[0134] [Seventh embodiment] In the lithium recovery device according to the third embodiment, no electrodes are disposed in the Li supply chamber and the Li recovery chamber, and the two chambers are separated on both sides by ion exchange membranes to provide a first electrode chamber and a second electrode chamber. + Ions other than Li move through the ion conductive membrane. + From this, it was found that the Li supply chamber and the Li recovery chamber were separated into several pairs, and the Li + By separating and connecting the chambers with an ion-conducting membrane that does not conduct ions, and by disposing a first electrode and a second electrode in the chambers at both ends, it is possible to process a large amount of Li source (Li-containing non-aqueous solution) with a single power source, thereby increasing the amount of Li recovered.

[0135] 18 , a 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 treatment tank 7A partitioned into six chambers by the electrolyte membrane 2 and the ion conductive membranes 31 and 33, a power source 5, a first electrode 41 connected to the positive electrode of the power source 5, and a second electrode 42C connected to the negative electrode. The electrolyte membranes 2 and the ion conductive membranes 31 and 33 are alternately arranged, with the ion exchange membrane 31 disposed at one end. Thus, the membranes 31, 2, 33, 2, and 33 are arranged in this order from one end, and the treatment tank 7A is partitioned into chambers 11, 12a, 13a, 12b, 13b, and 14. The first electrode 41 is provided in a first electrode chamber 11 at one end of the treatment tank 7A, separated by an ion exchange membrane 31, and the second electrode 42C is provided in a second electrode chamber 14 at the other end. The chambers 11 and 14 contain water (aqueous solutions S1 and S2), respectively. The chambers 12a and 12b are Li supply chambers containing a Li-containing non-aqueous solution FS. The chambers 13a and 13b are Li recovery chambers containing an aqueous solution RS for Li recovery. The multi-chamber lithium recovery device 10 may further include water supply devices 81 and 84 and circulation devices 82A and 83A, as necessary. The multi-chamber lithium recovery device 10 according to this embodiment is configured by connecting two lithium recovery devices 1D according to the third embodiment (see FIG. 7), with one second electrode chamber 14 removed between adjacent lithium recovery devices 1D, 1D, and further integrating the Li recovery chamber 13 (13a) of one of the devices with the first electrode chamber 11 of the other device. In FIG. 18, the multi-chamber lithium recovery device 10 includes two electrolyte membranes 2 and two sets of Li supply chambers and Li recovery chambers, but the number may be any number equal to or greater than two.

[0136] The treatment tank 7A has dimensions corresponding to the number of partitioned chambers, and other than that, it can have the same configuration as the treatment tank 7 of the lithium recovery device 1.

[0137] Similar to the circulation device 82 of the lithium recovery device 1, the circulation device 82A is a device that circulates the Li-containing non-aqueous solution FS so that the Li-containing non-aqueous solution FS is continuously replaced in each of the Li supply chambers 12a, 12b during operation and so that the Li-containing non-aqueous solution FS in contact with the electrolyte membrane 2 is continuously replaced. The circulation device 82A can have the same configuration as the circulation device 82, except that it is provided with a circulation path such as a pipe communicating with each of the Li supply chambers 12a, 12b. Furthermore, although one circulation device 82A circulates all of the Li-containing non-aqueous solutions FS in the Li supply chambers 12a, 12b collectively, a circulation device 82 may be provided for each of the Li supply chambers 12a, 12b to circulate the Li-containing non-aqueous solution FS in an independent system.

[0138] Similar to the circulation device 83 of the lithium recovery device 1, the circulation device 83A is a device that circulates the Li recovery aqueous solution RS so that the Li recovery aqueous solution RS is continuously replaced in each of the Li recovery chambers 13a, 13b during operation and so that the Li recovery aqueous solution RS in contact with the electrolyte membrane 2 is continuously replaced. The circulation device 83A can have the same configuration as the circulation device 83, except that it is provided with a circulation path such as a pipe communicating with each of the Li recovery chambers 13a, 13b. Alternatively, a circulation device 83 may be provided in each of the Li recovery chambers 13a, 13b, and the Li recovery aqueous solution RS may be circulated in an independent system.

[0139] The other elements of the multi-chamber lithium recovery device 10 according to this embodiment can be configured similarly to the elements of the lithium recovery devices 1 and 1D according to the first and third embodiments.

[0140] (Lithium Recovery Method) A lithium recovery method according to a seventh embodiment of the present invention will be described with reference to FIG. 19 . The lithium recovery method according to this embodiment is performed as follows using a multi-chamber lithium recovery device 10. Note that in FIG. 19 , the water supply devices 81, 84 and the circulation devices 82A, 83A are omitted. For identification purposes, the electrolyte membrane 2 is designated by a different reference numeral from the electrolyte membranes 21, 22. The electrolyte membrane 21 separates the Li supply chamber 12a from the Li recovery chamber 13a, and the electrolyte membrane 22 separates the Li supply chamber 12b from the Li recovery chamber 13b. The Li-containing non-aqueous solutions FS in the Li supply chambers 12a, 12b will be referred to as Li-containing non-aqueous solutions FSa, FSb, respectively, as appropriate. Similarly, the Li recovery aqueous solutions RS in the Li recovery chambers 13a, 13b will be referred to as Li recovery aqueous solutions RSa, RSb, respectively, as appropriate (the same applies to the modified examples described below).

[0141] In this embodiment, similarly to the first embodiment (see FIG. 2), 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 in the first electrode chamber 11 and the Li-containing non-aqueous solution FSa in the Li supply chamber 12a caused by the application of the voltage +V1 are similar to 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, a reaction represented by the following formula (1) or (5) occurs near the first electrode 41 to generate O, and as a result, H of H O in the aqueous solution S1 is converted to + permeates the ion exchange membrane 31 and moves to the Li-containing non-aqueous solution FSa in the Li supply chamber 12a, causing a reaction represented by the following formula (6). + The reaction of the following formula (7), in which the ions migrate into the electrolyte membrane 2, occurs near the surface of the electrolyte membrane 2.

[0142] Furthermore, application of the voltage +V1 causes the following reaction in the aqueous solution RSa for Li recovery in the Li recovery chamber 13a: H of water (H O) in the aqueous solution RSa for Li recovery + passes through the bipolar membrane 33 and moves to the Li-containing non-aqueous solution FSb in the Li supply chamber 12b. + As the amount of Li in the electrolyte membrane 21 decreases, the amount of Li in the electrolyte membrane 21 decreases to maintain the charge balance. +The reaction of the following formula (3), in which Li moves to the Li recovery aqueous solution RSa, occurs near the surface (back surface) of the electrolyte membrane 21 on the Li recovery chamber 13a side. In the Li recovery aqueous solution RSa, an electric field is generated in the direction from the electrolyte membrane 21 side to the bipolar membrane 33 side by applying a voltage +V1. + is moved away from the vicinity of the rear surface of the electrolyte membrane 21 by electrostatic attraction. On the other hand, in the Li-containing non-aqueous solution FSb in the Li supply chamber 12b, an electric field is generated in the direction from the bipolar membrane 33 side to the electrolyte membrane 22 side by application of the voltage +V1, and Li + is the cation in the Li-containing non-aqueous FSb solution, + , M n+ is attracted to the surface of the electrolyte membrane 22 by electrostatic attraction. + With the increase of Li in the Li-containing non-aqueous solution FSb, in order to maintain the charge balance, + The reaction of the following formula (7), in which the reactant is transferred into the electrolyte membrane 22, occurs near the surface of the electrolyte membrane 22. That is, in the Li recovery aqueous solution RSa and the Li-containing aqueous solution FSb, the same reactions as those in the aqueous solution S1 and the Li-containing aqueous solution FSa occur, respectively, and the Li recovery aqueous solution RS (RSa) in the Li recovery chamber 13a has the same effect as the aqueous solution S1.

[0143] 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 similar to the reactions in the aqueous solution S2 and the aqueous solution RS for Li recovery in the third embodiment (see FIG. 8). That is, in the aqueous solution S2, the reaction of the following formula (4) occurs near the second electrode 42C to form OH - This generates OH - passes through the bipolar membrane 33 and moves to the aqueous solution RSb for Li recovery in the Li recovery chamber 13b, and at the same time, H + passes through the bipolar membrane 33 and moves to the aqueous solution S2. In the aqueous solution RSb for recovering Li, H + reduction of OH - With the increase in +In the aqueous solution RSb for recovering Li, the application of a voltage +V1 generates an electric field in the direction from the electrolyte membrane 22 side to the bipolar membrane 33 side, and Li + are kept away from the vicinity of the rear surface of the electrolyte membrane 22 by electrostatic attraction.

[0144] (Modification) The multi-chamber lithium recovery device according to this embodiment, like the lithium recovery device 1C (see FIG. 4) according to the modification of the first embodiment, n- In the case where the aqueous solution for Li recovery RS contains water-soluble anions, anion exchange membranes 32, 34 can be applied to the first ion conductive membrane and the second ion conductive membrane. In the multi-chamber lithium recovery device 10A according to such a modification, as shown in FIG. 20, the aqueous solution for Li recovery RS contains the anions A contained in the Li-containing non-aqueous solution FS. n- For example, an anion exchange membrane 32 may be used as the first ion conductive membrane, and a bipolar membrane 33 or a proton conductive membrane may be used as the second ion conductive membrane. Furthermore, with regard to the second ion conductive membrane, the membrane disposed between the electrolyte membranes 2 and the membrane separating the second electrode chambers 14 may be of different types. In particular, as in the above embodiment, by using a bipolar membrane 33 or a proton conductive membrane as the second ion conductive membrane disposed between the electrolyte membranes 2, anions A are transferred to the aqueous solution RS for Li recovery. n- This can prevent the inclusion of

[0145] 21 , the multi-chamber lithium recovery device according to this embodiment may not be provided with the second electrode chamber 14, and the second electrode 42C may be disposed in the Li recovery chamber 13b, which is the end chamber opposite to the first electrode chamber 11. In the multi-chamber lithium recovery device 10B according to such a modification, a reaction similar to that in the aqueous Li recovery solution RS of the first embodiment (see FIG. 2 ) occurs in the aqueous Li recovery solution RSb in the Li recovery chamber 13b.

[0146] The multi-chamber lithium recovery device according to this embodiment, like the lithium recovery device 1B according to the second embodiment (see FIG. 5), is provided with two power sources and the voltages of each are set to appropriate values, thereby enabling a large amount of Li recovered per hour. As shown in FIG. 22, the multi-chamber lithium recovery device 10C according to this modification is provided with a third electrode 43 in contact with the electrolyte membrane 22 in the Li recovery chamber 13b adjacent to the second electrode chamber 14, like the lithium recovery device 1F according to the fourth embodiment (see FIG. 10). Furthermore, in a configuration in which the second electrode chamber 14 is not provided, like the multi-chamber lithium recovery device 10B according to the modification, the second electrode 42C is disposed in the Li recovery chamber 13b, spaced apart from the electrolyte membrane 22 and the third electrode 43, like the lithium recovery device 1B according to the second embodiment.

[0147] According to the multi-chamber lithium recovery device of this embodiment and its modified example, Li can be recovered from a non-aqueous solution in the same way as the lithium recovery device of the first embodiment, and further, the power consumption per amount of Li recovered can be reduced.

[0148] The lithium recovery device and lithium recovery method according to the present invention have been described above as embodiments for carrying out the present invention, but examples in which the effects of the present invention have been confirmed will be described below. It goes without saying that the present invention is not limited to these examples and the above-described embodiments, and that various changes and modifications based on these descriptions are also included in the spirit of the present invention.

[0149] [Experiment 1] The amount of lithium transferred per unit time due to voltage application was measured for the lithium recovery device and lithium recovery method according to the first embodiment of the present invention shown in FIG.

[0150] (Fabrication of Lithium Recovery Apparatus) The lithium recovery apparatus according to Example 1 of the present invention was fabricated using a plate-shaped La electrolyte membrane with a thickness of 0.5 mm. 0.57 Li 0.29The TiO3 (lithium ion conductive ceramics LLTO, manufactured by Toho Titanium Co., Ltd.) was used as the electrolyte membrane, and a bipolar membrane for water splitting (Neosepta, manufactured by Astom Corporation) was used as the ion conductive membrane. Both the electrolyte membrane and the ion conductive membrane were 50 mm long (height) x 50 mm wide (depth). The bipolar membrane and the electrolyte membrane were installed parallel to each other with a 70 mm gap between them in a glass treatment tank, dividing the tank into three compartments in one direction. A 40 mm x 30 mm Pt mesh electrode (41 in Figure 1) was placed directly opposite the ion conductive membrane in the first electrode compartment (11 in Figure 1) at the end divided by the ion conductive membrane. A 40 mm x 30 mm Ni mesh electrode (42 in Figure 1) was placed directly opposite the electrolyte membrane in the Li recovery compartment (13 in Figure 1) at the end divided by the electrolyte membrane, with a distance of 15 mm from the electrolyte membrane. The distance between the two electrodes was 100 mm. A power source was connected between the two electrodes, with the first electrode chamber side serving as the positive electrode, to form a lithium recovery device. An ammeter was inserted between the positive electrode of the power source and the Pt mesh electrode.

[0151] As a Li source, a 1 mol / L non-aqueous solution of lithium perchlorate (LiClO4) (solvent: EC and DMC in a volume ratio of 1:1) was prepared. + A 0.1 mol / L aqueous solution of lithium hydroxide (LiOH) was prepared as a supply source and an aqueous solution for Li recovery. 150 mL of a Li-containing non-aqueous solution was poured into the Li supply chamber of the lithium recovery device, which was separated by an ion conductive membrane and an electrolyte membrane. 130 mL of the LiOH aqueous solution was poured into the first electrode chamber and the Li recovery chamber, respectively, so that the electrodes were completely immersed in the solution.

[0152] As a comparative example, a lithium recovery device was prepared by installing an electrolyte membrane in a glass treatment tank and dividing it into two compartments, a Li supply chamber and a Li recovery chamber. A Pt mesh electrode was placed in the Li supply chamber, and a Ni mesh electrode was placed in the Li recovery chamber. A power supply and an ammeter were connected in the same manner as in the example. The distance between the electrodes was 7 mm. The electrolyte membrane and electrodes were the same as those in Example 1. The same LiClO4 non-aqueous solution and LiOH aqueous solution as in Example 1 were introduced into the Li supply chamber and the Li recovery chamber.

[0153] (Lithium recovery experiment) A DC voltage of 2 V was continuously applied from a power source, and the transition of the current value was measured with an ammeter. For Example 1 and the comparative example, the current value and the Li that moved this current value were measured. + The transition of the amount of movement per unit time converted as Li is shown in FIG. + The amount of movement per unit time was calculated by multiplying the current by the time and the Li atomic weight by the Faraday constant, where the Li atomic weight was 6.941 g / mol and the Faraday constant was 96485 C / mol.

[0154] As shown in FIG. 23, in Example 1, a sufficient current flows stably, and therefore, the Li content of the Li-containing non-aqueous solution can be reduced by electrodialysis. + It can be assumed that the current is moving to the water (LiOH aqueous solution) in the Li recovery chamber. + It hardly moved at all.

[0155] From the above, the lithium recovery device and the lithium recovery method according to the first embodiment of the present invention can + It was confirmed that Li can be stably recovered from a non-aqueous solution in which Li is dissolved in an organic solvent together with other cations as a Li source without decomposing the organic solvent.

[0156] [Experiment 2] For the lithium recovery method according to the fifth embodiment of the present invention shown in FIG. 12, the amount of lithium transferred per unit time due to voltage application was measured in the same manner as in Example 1.

[0157] The lithium recovery method according to Example 2 of the present invention used the lithium recovery device according to the comparative example of Experiment 1. A 1 mol / L LiPF ethanol solution was prepared as a Li source. + A 1 mol / L aqueous solution of sodium hydroxide (NaOH) was prepared as a source. 60 mL of LiPF ethanol solution and 70 mL of NaOH aqueous solution were placed in the Li supply chamber (reference numeral 12 in FIG. 12). Meanwhile, a 0.1 mol / L aqueous solution of LiOH was placed in the Li recovery chamber (reference numeral 13 in FIG. 12), as in Example 1.

[0158] A DC voltage of 2 V was continuously applied from the power supply, and the change in the current value was measured with an ammeter.+ FIG. 23 shows the transition of the movement amount per unit time converted as

[0159] As shown in FIG. 23, in Example 2 of the present invention, a sufficient current, about five times that of the comparative example in Experiment 1, flows stably. Therefore, as in Example 1, it is possible to obtain Li from a Li-containing non-aqueous solution by electrodialysis. + It can be assumed that the lithium ions are moving into the water (LiOH aqueous solution) in the Li recovery chamber.

[0160] As described above, the lithium recovery method according to the third embodiment of the present invention is similar to the first embodiment in that Li + It was confirmed that Li can be stably recovered from a non-aqueous solution in which Li is dissolved in an organic solvent together with other cations as a Li source without decomposing the organic solvent. Furthermore, a lithium recovery device with the same simple structure as the conventional one (comparative example) can be used.

[0161] [Experiment 3] For the lithium recovery device and lithium recovery method according to the second embodiment of the present invention shown in FIG. 5, the amount of lithium transferred per unit time due to voltage application was measured in the same manner as in Example 1.

[0162] (Fabrication of Lithium Recovery Apparatus) In the lithium recovery apparatus according to Example 3 of the present invention, the power source was a first power source, and a second power source was inserted between the negative electrode of the first power source and the Ni mesh electrode (reference numeral 42B in FIG. 5 ). Furthermore, a new Pt mesh electrode (reference numeral 43 in FIG. 5 ) was connected to the negative electrode of the first power source, and the electrode was placed in the Li recovery chamber so as to be in contact with the electrolyte membrane. The distance between the two electrodes in the Li recovery chamber was set to 55 mm. As in Example 1, a LiClO4 non-aqueous solution was introduced into the Li supply chamber, and a LiOH aqueous solution was introduced into the first electrode chamber and the Li recovery chamber.

[0163] (Lithium recovery experiment) A DC voltage of 2 V was continuously applied to the first power source and a DC voltage of 5 V was continuously applied to the second power source, and the transition of the current value was measured with an ammeter. + FIG. 24 shows the transition of the movement amount per unit time converted as

[0164] As shown in FIG. 24, in the lithium recovery device according to Example 3 of the present invention, a sufficient current flows stably, as in Example 1, and therefore, Li in the Li-containing non-aqueous solution can be recovered by electrodialysis. + It can be assumed that the amount of Li is about three times that of Example 1 per hour. + It can be assumed that the current is moving, which can increase the recovery speed. In addition, the current value gradually increased over time. This is assumed to be due to the temperature rise of the electrolyte membrane.

[0165] As described above, the lithium recovery device and the lithium recovery method according to the second embodiment of the present invention are similar to the first embodiment in that Li + It was confirmed that Li can be stably recovered without decomposing the organic solvent by using a non-aqueous solution in which Li is dissolved together with other cations in an organic solvent as a Li source. It was also confirmed that the recovery rate can be increased by providing two electrodes in the Li recovery chamber, as in the device for recovering Li contained in an aqueous solution (see Patent Document 3).

[0166] [Experiment 4] The movement of lithium was observed in the lithium recovery device and lithium recovery method according to the modified example of the first embodiment of the present invention shown in FIG.

[0167] The lithium recovery device according to Example 1 of Experiment 1 was used. A 1 mol / L LiPF non-aqueous solution (solvent: EC and DMC in a volume ratio of 1:1) was prepared as the Li source and the non-aqueous solution for Li recovery, and was placed in the Li supply chamber and the Li recovery chamber, respectively. Meanwhile, a 0.1 mol / L LiOH aqueous solution was placed in the first electrode chamber, as in Example 1.

[0168] A DC voltage of 10 V was continuously applied from the power supply with the negative electrode potential set to −5 V. After 24 hours of application, it was visually confirmed from outside the treatment tank that silver metallic lithium had been deposited on the surface of the Ni mesh electrode in the Li recovery chamber. In this way, it was confirmed that the lithium recovery device and lithium recovery method according to the modified example of the first embodiment of the present invention can recover metallic Li in the Li recovery chamber.

[0169] 10, 10A, 10B, 10C Multi-chamber lithium recovery device 1, 1A to 1H, 1J, 1K Lithium recovery device 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 conductive membrane) 41, 41A First electrode 42, 42A, 42B Second electrode 43 Third electrode 5, 5B Power source 51 First power source 52 Second power source 7, 7A Treatment tank 81, 84 Water supply device 82, 82A Circulation device 83, 83A Circulation device FS Li-containing non-aqueous solution RS Aqueous solution for Li recovery (water) RSA Non-aqueous solution for Li recovery (organic solvent) S1, S2 Aqueous solution (water)

Claims

1. A lithium recovery device comprising: a treatment tank partitioned into a first chamber, a second chamber, and a third chamber in that order; a lithium ion conductive electrolyte membrane partitioning the treatment tank into the first chamber and the second chamber; a first ion conductive membrane partitioning the treatment tank into the second chamber and the third chamber; a first electrode provided in the third chamber; a second electrode provided in a chamber at the end of the treatment tank opposite the partitioned third chamber; and a power source having a positive electrode connected to the first electrode and a negative electrode connected to the second electrode, the lithium recovery device transferring lithium ions from a non-aqueous solution containing lithium ions contained in the second chamber to water or an organic solvent contained in the first chamber, wherein the first ion conductive membrane conducts at least one type of cation other than lithium ions, or at least one type of anion that is water-soluble and contained in the non-aqueous solution, and the third chamber contains water.

2. The lithium recovery device as described in claim 1, further comprising a second ion conductive membrane that does not conduct lithium ions and divides the treatment tank into the first chamber and a fourth chamber, the second electrode is provided in the fourth chamber, and water is stored in the fourth chamber.

3. A lithium recovery device comprising: a treatment tank partitioned in this order into a second chamber, a first chamber, and a third chamber; a lithium ion conductive electrolyte membrane partitioning the treatment tank into the first chamber and the second chamber; a second ion conductive membrane partitioning the treatment tank into the first chamber and the third chamber and not conducting lithium ions; a first electrode provided in the second chamber; a second electrode provided in the third chamber; and a power source having a positive electrode connected to the first electrode and a negative electrode connected to the second electrode, the lithium recovery device transferring lithium ions from a non-aqueous solution containing lithium ions contained in the second chamber to water or an organic solvent contained in the first chamber, wherein water is contained in the third chamber, and water is further contained in the second chamber.

4. A lithium recovery device as described in claim 2 or claim 3, wherein an organic solvent is contained in the first chamber, an aqueous solution having anions soluble in the organic solvent dissolved therein is contained in a chamber of the treatment tank having the second electrode, and the second ion conductive membrane conducts the anions.

5. The lithium recovery device according to claim 1, wherein the first chamber contains an organic solvent, and the power source applies a voltage such that the potential of the second electrode is equal to or lower than a lithium ion reduction potential.

6. The lithium recovery device according to any one of claims 1 to 4, wherein the power source is formed by connecting a first power source and a second power source in series in that order from the positive side, and further comprises a third electrode connected to the negative electrode of the first power source, spaced apart from the second electrode, and arranged in contact with or facing the surface of the lithium ion conductive electrolyte membrane on the first chamber side, and wherein water or an organic solvent having anions dissolved therein is contained in the first chamber.

7. A method for recovering lithium, comprising the steps of: transferring lithium ions contained in a non-aqueous solution contained in a second chamber of a treatment tank partitioned into a first chamber and a second chamber by a lithium ion conductive electrolyte membrane to water or an organic solvent contained in the first chamber; wherein the treatment tank is further partitioned into the second chamber and a third chamber by a first ion conductive membrane that conducts at least one type of cation other than lithium ions, or at least one type of anion that is water-soluble and contained in the non-aqueous solution, and water is contained in the third chamber; and a power source connected with the first electrode as positive applies a voltage between a first electrode provided in the third chamber and a second electrode provided in a chamber at the end opposite to the partitioned third chamber of the treatment tank.

8. A method for recovering lithium in a treatment tank partitioned into a first chamber and a second chamber by a lithium ion conductive electrolyte membrane, in which lithium ions contained in a non-aqueous solution contained in the second chamber are transferred to water or an organic solvent contained in the first chamber, the method being characterized in that water is further contained in the second chamber, and a power source connected with the first electrode as positive applies a voltage between a first electrode provided in the second chamber and a second electrode provided in a chamber at the opposite end of the partitioned second chamber of the treatment tank.

9. A method for recovering lithium as described in claim 7 or claim 8, wherein the treatment tank is further divided into the first chamber and a fourth chamber by a second ion conductive membrane that does not conduct lithium ions, the second electrode is provided in the fourth chamber, and water is contained in the fourth chamber.

10. A method for recovering lithium as described in claim 9, wherein an organic solvent is contained in the first chamber, an aqueous solution having anions soluble in the organic solvent dissolved therein is contained in a chamber of the treatment tank having the second electrode, and the second ion conductive membrane conducts the anions.

11. The method for recovering lithium according to claim 7 or 8, wherein an organic solvent is contained in the first chamber, and the power source applies a voltage such that the potential of the second electrode is equal to or lower than a lithium ion reduction potential.

12. A method for recovering lithium according to any one of claims 7 to 10, wherein the first chamber contains water or an organic solvent having dissolved therein anions, the power source comprises a first power source and a second power source connected in series from the positive side, and a third electrode is connected to the negative electrode of the first power source, the third electrode being spaced apart from the second electrode and being in contact with or facing the surface of the lithium ion conductive electrolyte membrane on the first chamber side.

13. A multi-chamber lithium recovery device comprising: two or more lithium ion conductive electrolyte membranes; a first ion conductive membrane disposed on one end side of the lithium ion conductive electrolyte membrane disposed first from one end side; a second ion conductive membrane which does not conduct lithium ions and is disposed between the lithium ion conductive electrolyte membranes; a treatment tank partitioned into five or more chambers by the first ion conductive membrane, the lithium ion conductive electrolyte membrane, and the second ion conductive membrane; a first electrode provided in the chamber at one end of the treatment tank, and a second electrode provided in the chamber at the other end; and a power source having a positive electrode connected to the first electrode and a negative electrode connected to the second electrode, wherein water is contained in the chamber at one end of the treatment tank, and lithium ions are transferred from a non-aqueous solution containing lithium ions contained at one end of two adjacent chambers partitioned by the lithium ion conductive electrolyte membrane to water contained at the other end.

14. A multi-chamber lithium recovery device as described in claim 13, further comprising a second ion conductive membrane that separates the treatment tank between the lithium ion conductive electrolyte membrane that is the first from the other end side and the second electrode, and water is stored in the chamber at the other end of the treatment tank separated by the second ion conductive membrane.

15. A multi-chamber lithium recovery device as described in claim 13 or claim 14, wherein the power source is formed by connecting a first power source and a second power source in series in that order from the positive side, and further comprises a third electrode connected to the negative electrode of the first power source, spaced apart from the second electrode, and arranged in contact with or facing the surface of the other end side of the lithium ion conductive electrolyte membrane that is first arranged from the other end side.

16. A method for recovering lithium in a treatment tank divided into five or more compartments by ion conductive membranes and lithium ion conductive electrolyte membranes arranged alternately from one end side, in which lithium ions are transferred from a non-aqueous solution containing lithium ions contained in one of two adjacent compartments divided by the lithium ion conductive electrolyte membrane to water contained in the other compartment, wherein the ion conductive membrane arranged between the lithium ion conductive electrolyte membranes does not conduct lithium ions, water is contained in the compartment at one end of the treatment tank, and a power source connected with the first electrode as positive applies a voltage between a first electrode provided in the compartment at one end of the treatment tank and a second electrode provided in the compartment at the other end, and lithium ions are transferred from the non-aqueous solution containing lithium ions contained at one end side of the two adjacent compartments to water contained at the other end side.

17. A method for recovering lithium as described in claim 16, wherein the treatment tank is partitioned by an ion conductive membrane that does not conduct lithium ions and is disposed between the lithium ion conductive electrolyte membrane that is the first from the other end side and the second electrode, and water is contained in the chamber at the other end of the treatment tank partitioned by the ion conductive membrane.

18. A method for recovering lithium as described in claim 16 or claim 17, wherein the power source comprises a first power source and a second power source connected in series in that order from the positive side, and a third electrode is connected to the negative electrode of the first power source, the third electrode being spaced apart from the second electrode and arranged in contact with or facing the surface of the other end side of the lithium ion conductive electrolyte membrane that is the first electrode from the other end side.

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