Lithium ion recovery member and Lithium recovery device using the same

Abstract

Provided are: Li ion recovery member comprising a permselective membrane including a Li ion conductor comprising an inorganic material, electrodes, and a reticular elastic body, the electrodes being provided on at least one main surface side of the permselective membrane, at least one electrode of the electrodes comprising a porous electrode or a membrane electrode, and the porous electrode or membrane electrode being sandwiched by the reticular elastic body and the permselective membrane; and a Li recovery device which has the Li ion recovery member and which comprises an electrolytic cell for Li ion recovery for recovering Li ions by electrodialysis, whereby the occurrence of damage to the permselective membrane can be suppressed and stable Li ion recovery over a long period can be realized, even when the Li recovery device is increased in size.

Description

[Technical Field]

[0001] The present invention relates to a Li ion recovery member and a Li recovery device using the same. [Background technology]

[0002] With the recent rapid spread of information-related devices and communication devices such as personal computers, video cameras, and mobile phones, the development of batteries to be used as their power sources has become increasingly important. Conventionally, batteries used for such applications have used electrolytes containing flammable organic solvents, but by making batteries all-solid-state, flammable organic solvents are not used in the battery, safety devices can be simplified, and manufacturing costs and productivity can be improved. Therefore, batteries in which the electrolyte is replaced with a solid electrolyte layer are being developed.

[0003] Lithium secondary batteries and the like are used as batteries for the above-mentioned applications, and in recent years, their use in hybrid cars and electric vehicles, which are being developed to comply with carbon dioxide emission regulations, has also been considered. Securing lithium sources is therefore more urgent than ever, and as part of this effort, technologies for recovering lithium by recycling lithium secondary batteries have been developed (see, for example, Patent Document 1). Furthermore, an ion-exchange membrane electrolytic cell using an ion-exchange membrane is known as a technology for recovering sodium ions (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-034315 [Patent Document 2] Japanese Patent Application Laid-Open No. 2000-178782 Summary of the Invention [Problem to be solved by the invention]

[0005] Conventionally, an ion exchange membrane electrolytic cell as described in Patent Document 2 is known, but it uses an ion exchange membrane (Nafion N-962 manufactured by DuPont) and is not capable of selectively recovering lithium ions. On the other hand, the technology described in Patent Document 1 recovers metal ions from a stock solution containing metal ions such as lithium using a selectively permeable membrane made of an ion conductor. Among metal ions, there are no ion exchange membranes that can recover lithium ions. Therefore, the technology described in Patent Document 1 attempts to recover lithium ions by using a lithium ion conductor as a selectively permeable membrane.

[0006] In the technology described in Patent Document 1, the lithium ion conductor used in the selectively permeable membrane is a sintered plate made of a powder of a metal oxide, such as a superlithium ion conductor having a Li-substituted NASICON-type crystal. To expand the scale of lithium ion recovery, the selectively permeable membrane must be enlarged, but enlarging a sintered membrane is extremely difficult. Even if the membrane can be enlarged, the larger it becomes, the more likely it is to break during transportation or installation in the device, or to crack due to vibration of the device during lithium ion recovery. In addition, a larger selectively permeable membrane becomes heavy, making it extremely difficult to maintain the device in a state where water leakage is suppressed during lithium ion recovery. Furthermore, in the technology described in Patent Document 1, the positional relationship between the selectively permeable membrane and the electrodes is important for improving the lithium recovery rate, but no specific measures regarding the arrangement of a larger device are disclosed. With the increasing demand for lithium, there is a greater demand for improved lithium recovery efficiency and, at the same time, a demand for expanding the scale of lithium ion recovery. However, the above circumstances have created a problem in that it is not possible to fully address these challenges.

[0007] The present invention has been made in consideration of the above circumstances, and aims to provide a Li-ion recovery member that can suppress damage to the selective permeation membrane and achieve stable Li-ion recovery over a long period of time, even if the Li recovery device is enlarged, and a Li recovery device using the same. [Means for solving the problem]

[0008] As a result of extensive research into solving the above problems, the present inventors have found that the problems can be solved by the following invention.

[0009] 1. A device comprising a selectively permeable membrane containing an inorganic Li ion conductor and electrodes; the electrode is provided on at least one main surface of the permselective membrane, At least one of the electrodes is a porous electrode or a membrane electrode, the porous electrode or membrane electrode is sandwiched between a reticular elastic body and the permselective membrane; Li-ion recovery material. 2. The Li-ion recovery member according to 1 above, wherein the porous electrode or membrane electrode is provided on both main surfaces of the permselective membrane. 3. The Li ion recovery member according to the above item 1 or 2, further comprising an electrode made of a rigid conductive porous plate. 4. The Li-ion recovery member according to 3 above, wherein the porous electrode or the membrane electrode is provided on one main surface side of the permselective membrane, and the rigid conductive porous plate is provided on the other main surface. 5. The Li-ion recovery member according to 3 above, wherein the porous electrode or the membrane electrode and the rigid conductive porous plate are provided on one main surface side of the permselective membrane. 6. The Li-ion recovery member according to the above item 5, wherein the porous electrode or the membrane electrode and the rigid conductive porous plate are provided on both main surfaces of the permselective membrane. 7. The Li-ion recovery member according to the above item 5 or 6, wherein the rigid conductive porous plate is provided so as to sandwich the porous electrode or membrane electrode and the reticulated elastic body. 8. The selectively permeable membrane comprises a plurality of selectively permeable membrane units and adhesive portions arranged on the same surface; The adhesive portion is provided in a lattice or honeycomb shape, 8. The Li-ion recovery member according to any one of the above 1 to 7, wherein the plurality of permselective membrane units are arranged in regions partitioned by the adhesive portions and are bonded to one another by the adhesive portions. 9. The Li-ion recovery member according to the above item 8, wherein a current collector is provided at the adhesive portion. 10. The Li ion recovery member according to any one of the above 1 to 9, wherein the Li ion conductor contains an oxide or oxynitride containing Li. 11. A Li recovery device having a Li ion recovery member according to any one of 1 to 10 above and including a Li ion recovery electrolytic cell for recovering Li ions by electrodialysis. 12. A Li recovery device as described in claim 11 above, which has a plurality of the Li ion recovery members, and the plurality of Li ion recovery members are connected so that the main surface of the selective permeable membrane of one Li ion recovery member faces the main surface of the selective permeable membrane of another Li ion recovery member. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a Li-ion recovery member that can suppress damage to the selective permeation membrane and achieve stable Li-ion recovery for a long period of time, even if the Li recovery device is enlarged, and a Li recovery device using the same. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic diagram showing a cross section of one aspect of a Li-ion recovery member of the present embodiment. [Figure 2] 1 is a schematic diagram showing a cross section of one aspect of a Li-ion recovery member of the present embodiment. [Figure 3] 2A and 2B are schematic diagrams showing the front and cross section of one mode of a permselective membrane in the Li-ion recovery member of the present embodiment. [Figure 4] 1 is a schematic diagram showing a cross section of one aspect of a Li ion recovery electrolytic cell in a Li recovery device of the present embodiment. FIG. [Figure 5] 1 is a schematic diagram showing a cross section of one aspect of a Li ion recovery electrolytic cell in a Li recovery device of the present embodiment. FIG. [Figure 6]1 is a schematic diagram showing a cross section of one aspect of a Li ion recovery electrolytic cell in a Li recovery device of the present embodiment. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, a Li-ion recovery member and a Li recovery device according to one embodiment of the present invention (hereinafter referred to as "this embodiment") will be described. Note that the Li-ion recovery member and the Li recovery device according to one embodiment of the present invention are merely embodiments of the Li-ion recovery member and the Li recovery device of the present invention, and the present invention is not limited to the Li-ion recovery member and the Li recovery device according to one embodiment of the present invention. Furthermore, in this specification, lithium means both lithium and lithium ions, and should be interpreted appropriately unless technical contradictions arise.

[0013] [Li-ion recovery material] The Li-ion recovery member of this embodiment comprises a selectively permeable membrane containing a Li-ion conductor made of an inorganic material, and electrodes, the electrodes being provided on at least one main surface of the selectively permeable membrane, at least one of the electrodes being a porous electrode or a membrane electrode, and the porous electrode or membrane electrode being sandwiched between a reticular elastic body and the selectively permeable membrane.

[0014] As described above, it is not only difficult to increase the size of a permselective membrane, but even if it is possible to increase the size, there are problems such as strength and weight, making it extremely difficult to accommodate increases in the size of the device by increasing the size of the permselective membrane. In this regard, the Li-ion recovery member of this embodiment employs a configuration in which a porous electrode or a membrane electrode is sandwiched between a reticular elastic body and a permselective membrane. With the Li-ion recovery member of this embodiment, when an increase in size is required, it is possible to accommodate the increase in size by combining multiple such configurations rather than increasing the size of the configuration itself. Furthermore, as mentioned above, when the permselective membrane is enlarged, the strength of the membrane decreases, which can cause damage. In this regard, since it is easy to enlarge the porous electrode, the use of a larger porous electrode can prevent damage to the permselective membrane and enable stable Li ion recovery over a long period of time. Furthermore, when the permselective membrane is enlarged, it becomes necessary to consider the arrangement of the permselective membrane and the electrodes. In this regard, the Li ion recovery member of this embodiment can stably recover Li ions with just one of the above-described configurations. Therefore, by simply combining multiple configurations, it becomes possible to accommodate increases in the size of the device without having to consider the arrangement of the permselective membrane and the electrodes. Therefore, with the conventional technology disclosed in Patent Document 1, it was extremely difficult to accommodate increases in the size of the device. However, with the Li-ion recovery member of this embodiment, it is possible to easily accommodate increases in size, regardless of whether the selective permeation membrane is enlarged or not, and it is also possible to suppress damage to the selective permeation membrane and achieve stable Li-ion recovery over a long period of time.

[0015] (selectively permeable membrane) The permselective membrane used in this embodiment contains an inorganic Li-ion conductor. When recovering only Li ions, it has been extremely difficult to recover them using an organic ion exchange membrane. In this embodiment, by adopting a permselective membrane containing an inorganic Li-ion conductor instead of an organic ion exchange membrane, it has become possible to stably recover Li ions, which was difficult to achieve using an ion exchange membrane.

[0016] The inorganic Li-ion conductor can be any inorganic material that has Li-ion conductivity, and is not particularly limited. For example, a super Li-ion conductor is a preferred example. The use of a super Li-ion conductor can increase the ionic current of Li ions flowing between electrodes, thereby improving the Li recovery efficiency. Here, Li ions contained in the aqueous solution exist as Li hydrate ions, with water molecules coordinating around them. Therefore, to further increase the ionic current, it is effective to create a condition where water molecules can be easily removed from the surface of the permselective membrane (the interface between the permselective membrane and the raw solution). For this reason, it is preferable that a Li adsorption layer that adsorbs Li ions (excluding hydrates) in the Li ion extract is formed on the surface of the permselective membrane. That is, it is preferable that the permselective membrane is one that has been subjected to a surface Li adsorption treatment. As the Li adsorption layer, one that is formed by modifying the surface of the material that constitutes the permselective membrane, as described below, is preferred.

[0017] Preferred examples of inorganic Li-ion conductor materials constituting the permselective membrane body include the following oxides, oxynitrides, etc. containing Li. That is, the permselective membrane preferably contains the following oxides, oxynitrides, etc. containing Li. Examples of oxides containing Li include lithium lanthanum titanate (Li x ,La y )TiO z (where x=3a-2b, y=2 / 3-a, z=3-b, 0<a≦1 / 6、0≦b≦0.06、x> 0) (hereinafter also referred to as "LLTO"), lithium lanthanum zirconate: Li7La3Zr2O 12 (hereinafter also referred to as "LLZO"), lithium lanthanum niobate: Li5La3Nb2O 12 , lithium lanthanum tantalate: Li5La3Ta2O 12 The LLTO is more specifically Li 0.29 La 0.57 TiO3 (a≒0.1, b≒0) can be used.

[0018] These materials can be obtained as sintered bodies by mixing particles made of these materials with sintering aids and sintering the mixture at high temperatures (above 1000°C). In this case, the surface of the Li-permselective membrane can be configured as a porous structure in which fine particles made of LLTO are bonded (sintered), thereby increasing the effective surface area of ​​the Li-permselective membrane itself. This is true not only for LLTO, but also for other Li-containing oxides and oxynitrides, which will be described later.

[0019] As the super Li ion conductor that can be used as the material for constituting the permselective membrane body, in addition to the above-mentioned LLTO, LLZO, etc. as an oxide containing Li, for example, Li substituted NASICON (Na Super Ionic Conductor) type crystal, 1+x+y Al x (Ti,Ge) 2-x Si y P 3-y O 12 (where 0≦x≦0.6, 0≦y≦0.6) (Li2O-Al2O3-SiO2-P2O5-TiO2-GeO2 system, hereinafter also referred to as "LASiPTiGeO") and the like are also included.

[0020] Preferred examples of oxynitrides containing Li include lithium phosphate oxynite (Li3PON, hereinafter also referred to as "LiPON"), nitride of LLTO (LLTON), nitride of LLZO (LLZON), nitride of LASiPTiGeO (LASiPTiGeON), and the like.

[0021] The above-mentioned super Li-ion conductors, such as oxides and oxynitrides containing Li, contain Li as one of their constituent elements, and exhibit ionic conductivity when Li ions outside the crystal move between Li sites in the crystal. Li ions flow through the Li-selective membrane itself, but sodium ions cannot flow within the Li-selective membrane. In this case, it is the Li ions (Li +) and the Li hydrate ions present in the original solution along with the Li ions cannot enter the Li sites and therefore do not conduct through the crystal. In this respect, it is the same as the Li permselective membrane described in WO2015 / 020121.

[0022] Here, if a large amount of Li ions in particular are adsorbed onto the surface of the permselective membrane body using the Li adsorption layer, the water molecules of the Li hydrated ions are removed during adsorption, leaving only Li ions, thereby increasing the Li ion conduction efficiency (ionic current flowing through the permselective membrane body) from the raw liquid side (one main surface side) of the Li permselective membrane body to the recovered liquid side (the other main surface side).

[0023] The permselective membrane may be formed by a single permselective membrane, or may be formed as an assembly of multiple permselective membranes. A preferred assembly of multiple permselective membranes is, for example, the configuration shown in Figure 3 (3-1), which consists of multiple permselective membrane units 21 and adhesive sections 22 arranged on the same surface, with the adhesive sections arranged in a lattice pattern, and the multiple permselective membrane units arranged in areas partitioned by the lattice-shaped adhesive sections and bonded to each other by the adhesive sections. While Figure 3 (3-1) shows a lattice pattern, the configuration is not limited to a lattice pattern and may be, for example, a linear (stripe) pattern or a honeycomb pattern, with the honeycomb pattern being preferred from the viewpoint of shape stability. Examples of adhesives used in the above-mentioned adhesive portion include epoxy resins, silicone resins, ceramic-containing adhesives, and the like, which are resistant to alkali.

[0024] Furthermore, as shown in Figure 3 (3-2), when the permselective membrane is an assembly of multiple permselective membranes, it is preferable to provide a current collector 23 at the adhesive portion 22. This allows for reliable current flow to the electrodes while effectively utilizing the surface of the permselective membrane. Furthermore, since the required number of permselective membrane units can be combined depending on the desired scale, it is easier to accommodate. The size of the permselective membrane unit is usually 10 cm to 3000 cm in length and 10 cm to 2000 cm in width, preferably 30 cm to 2800 cm in length and 30 cm to 1800 cm in width. The thickness of the permselective membrane unit is usually 0.1 cm to 10 cm, preferably 1 cm to 6 cm. If the dimensions of the permselective membrane unit are within the above ranges, it can be easily fabricated and has sufficient strength.

[0025] The current collector is preferably provided on at least one of the main surfaces of the permselective membrane, and more preferably on both of the main surfaces. The current collector is preferably made of a material having high electrical conductivity, and is also preferably made of a material having alkali resistance because it is expected to be used in an alkaline atmosphere. Examples of such materials include SUS, Ti, Ti-Ir alloys, etc., which are materials that can be used as electrodes, as described below, as well as nickel, nickel alloys, carbon felt, etc.

[0026] (electrode) At least one of the electrodes used in this embodiment is a porous electrode or a membrane electrode. A porous electrode is an electrode made of a porous body having fine pores, and specific examples thereof include carbon felt, carbon sheet, metal nonwoven fabric, metal mesh, etc. As the metal constituting these porous electrodes, any metal commonly used for electrodes can be used without limitation, but it is preferable to use a metal material that does not undergo electrochemical reactions and is resistant to alkalis, and preferred examples thereof include SUS, Ti, and Ti-Ir alloys.

[0027] There are no particular limitations on the porous electrode as long as it is made of a porous body having pores. The pores usually have an opening area of ​​0.05 to 1.0 mm. 2 It is sufficient if the thickness is about 0.1 to 0.5 mm. 2The ratio of the total open pore area to the surface area of ​​the porous body is preferably 10% or more, more preferably 20% or more, and the upper limit is preferably 50% or less, more preferably 40% or less. The pores in the porous electrode facilitate uniform current flow, and its surface contact with the permselective membrane and flexibility reduce local stress. Furthermore, when enlarging the permselective membrane, it is easy to enlarge the porous electrode, such as a metal nonwoven fabric. The permselective membrane acts as a partition between the raw solution and the recovered solution during Li-ion recovery, and is under pressure to prevent water leakage. However, the membrane may be damaged if the pressure applied to it is uneven or if there are hard protrusions. Therefore, by using porous electrodes and placing them on both sides of the permselective membrane to give both sides the same structure, the pressure applied to both sides of the membrane can be equalized across the entire surface. As a result, the permselective membrane is prevented from being damaged by localized force, making it easier to achieve stable long-term Li-ion recovery. Furthermore, by placing porous electrodes on both sides of the selectively permeable membrane, the number of contact points between the membrane and the porous electrodes increases on both sides of the membrane, and a uniform and strong electric field is applied within the surface of the selectively permeable membrane, which is expected to improve the recovery rate of Li ions.

[0028] A film electrode is a film-like electrode, and examples thereof include a metal film made of the metal forming the porous electrode. In this case, the thickness of the metal film can be determined appropriately depending on the desired performance, size, etc., and cannot be generalized because it varies depending on the film formation method. However, when a vapor deposition method, sputtering method, etc. is used, the thickness is usually about 1 to 5,000 nm, preferably 10 to 3,500 nm, more preferably 50 to 2,500 nm, and even more preferably 100 to 2,000 nm. When the metal film is formed by applying a liquid composition containing the metal that forms the electrode, the thickness is usually about 0.1 to 100 μm, preferably 0.5 to 70 μm, more preferably 1 to 50 μm, and even more preferably 5 to 20 μm.

[0029] In this embodiment, the porous electrode or the membrane electrode may be used as either the anode or the cathode. The porous electrode and the membrane electrode may be used alone or in combination of two or more kinds.

[0030] In this embodiment, at least one of the electrodes other than the porous body electrode or membrane electrode may further comprise an electrode made of a rigid conductive perforated plate. By using a rigid conductive perforated plate, parallelism between the multiple permselective membranes can be maintained, and the rigidity of the conductive perforated plate allows for the application of a higher, more uniform pressure to the permselective membranes. This prevents damage to the permselective membranes and facilitates stable long-term Li-ion recovery. Preferred examples of rigid conductive porous plates include metal plates having openings such as expanded metal, punched metal, etc. Examples of metals constituting expanded metal, punched metal, etc. include those exemplified as metals that can be used for the electrodes. When openings are present, the ratio of the openings to the total area is preferably 5 to 50%, more preferably 10 to 45%, and even more preferably 20 to 35%. When the ratio of the openings is within the above range, local stress can be suppressed, which prevents damage to the permselective membrane and makes it easier to achieve stable long-term Li-ion recovery.

[0031] (Reticulated elastic body) The reticulated elastic body used in this embodiment is provided to fix at least one electrode, that is, a porous electrode or a membrane electrode, to the selectively permeable membrane. These electrodes are sandwiched between the reticulated elastic body and the selectively permeable membrane, and by using a reticulated elastic body, which can be easily made large, it is possible to fix these electrodes, such as the porous electrode or membrane electrode, so that they are in reliable contact with the selectively permeable membrane while suppressing damage to the electrodes, even when the device is made large, particularly when the device is made large by increasing the size of the selectively permeable membrane.

[0032] The reticulated elastic body can be any material that can fix an electrode, such as a porous electrode or a membrane electrode, in contact with the permselective membrane without damaging the electrode or the permselective membrane, and a conductive or insulating elastic mat is a preferred example. The permselective membrane may be damaged if the pressure applied thereto is uneven or if there are hard protrusions. However, by using the conductive or insulating elastic mat as the reticulated elastic body, damage to the permselective membrane can be suppressed, making it easier to achieve stable long-term Li-ion recovery.

[0033] Preferred examples of conductive elastic mats include wire meshes woven by various methods using metal wires, such as plain weave wire mesh, plain tatami weave wire mesh, twill weave wire mesh, twill tatami weave wire mesh, herringbone weave wire mesh, and knitted weave wire mesh; crimped wire meshes obtained by crimping these wire meshes; and aggregates of metal wool, with knitted weave wire mesh being particularly preferred. In addition to these wire meshes, flexible materials such as springs (metal coils) can also be used. When using springs, the direction of their expansion and contraction should be parallel to the main surface of the permselective membrane.

[0034] The use of such an elastic mat makes it easier to fix the electrodes so that they are in contact with the permselective membrane without damaging the electrodes or the permselective membrane, makes it easier to suppress local stress, and promotes the rise of bubbles of hydrogen and the like that are generated during use, allowing for more stable use. In this embodiment, when using such a wire mesh, it is possible to use a combination of multiple sheets to achieve a desired thickness. From a similar perspective, when using a wire mesh as an elastic mat, it is sufficient to use one with openings (mesh openings) of about 0.5 to 20 mm, with openings (mesh openings) of about 1 to 10 mm being preferred, and when using a crimped wire mesh, the process difference between the crimp peaks and valleys is usually about 1 to 40 mm, with 2 to 30 mm being preferred.

[0035] The reticulated elastic body is elastic and, from the viewpoint of easily fixing the electrodes in contact with the permselective membrane without damaging the electrodes or the permselective membrane and further suppressing local stress, preferably has the following properties: Note that the following properties are common to both the case where the reticulated elastic body is the wire mesh and the case where the reticulated elastic body is a spring (metallic coil body). The resilience when the mesh elastic body is compressed 50% in the thickness direction is 30 to 50 g / cm 2 It is preferable that the density is 35 to 45 g / cm 2 It is more preferable that the resilience when the reticulated elastic body is compressed and deformed by 20% in the thickness direction is 10 to 30 g / cm. 2 is preferably 15 to 25 g / cm 2 It is more preferable that: Furthermore, as for the spring elasticity, there is no particular restriction on the spring constant as long as the above-mentioned repulsive force is maintained, but the deformation width in the thickness direction at which the spring constant shows a constant value is preferably 1 to 30 mm, and more preferably 2 to 20 mm.

[0036] The porosity of the reticular elastic body during use is preferably 20% or more, more preferably 30% or more. Using the reticular elastic body with such a porosity makes it easier to fix the electrode in contact with the permselective membrane, makes it easier to suppress local stress, and promotes the rise of bubbles such as hydrogen bubbles that are generated during use, allowing for more stable use.

[0037] The material constituting the reticulated elastic body is not particularly limited. However, from the viewpoint of more efficient recovery of Li ions, it is preferable to use a material with high electrical conductivity in consideration of its use as a current collector. Furthermore, since it is expected to be used in an alkaline atmosphere, it is preferable to use a material that is resistant to alkalinity. Examples of such materials include SUS, Ti, Ti-Ir alloys, etc., which are listed as examples of materials that can be used for the electrodes, as well as carbon steel, nickel, nickel alloys, etc. Considering cost, materials such as carbon steel and SUS plated with nickel are preferred.

[0038] The insulating elastic mat is preferably made of a material that has a certain level of strength, is permeable to the aqueous solution containing the ions to be recovered, and is chemically stable against the aqueous solution, and is preferably a nonwoven fabric, separator, or the like. The nonwoven fabric is preferably made of vegetable fiber, animal fiber, mineral fiber, or chemical fiber, and the chemical fiber is preferably rayon, nylon, polyester, acrylic fiber, or aramid fiber. The separator is preferably made of a polyolefin or urethane resin with fine pores. Depending on the shape of the recovery member, such as a stack type or a cylindrical type, it can also serve as a spacer for the passage of the raw solution and the recovered solution. Unlike a conductive elastic mat, it does not function as a current collector, but it has the advantage of not causing unnecessary electrode reactions. The elastic mat may be any of the above elastic mats alone or may be a layered structure of multiple mats made of the same or different materials. For example, the above insulating elastic mat may be used alone, the above conductive elastic mat may be used alone, multiple insulating elastic mats may be used in combination, multiple conductive elastic mats may be used in combination, or insulating and conductive elastic mats may be used in combination.

[0039] (Installation location) Regarding the Li-ion recovery member of this embodiment, possible and preferred embodiments regarding the relative positions of the permselective membrane, electrodes, and reticular elastic body will be described with reference to FIGS. The electrode 3 of the porous body electrode or membrane electrode must be provided on at least one main surface of the permselective membrane 2, and must be sandwiched between the reticulated elastic body 4 and the permselective membrane 2. Preferred examples of such a configuration include those shown in Figures 1 (1-1) and 1-2. As shown in these drawings, the electrode 3 of the porous body electrode or membrane electrode may be provided on one main surface of the permselective membrane 2 and sandwiched between the reticulated elastic body 4 and the permselective membrane 2, or may be provided on both main surfaces of the permselective membrane 2 and sandwiched between the reticulated elastic body 4 and the permselective membrane 2. As shown in these drawings, the electrode 3 of the porous body electrode or membrane electrode is preferably provided on the main surface of the permselective membrane 2 (provided so as to be in contact with the main surface).

[0040] Although not shown in these figures, when electrodes are provided on both main surfaces of the permselective membrane, the electrode on one main surface may be sandwiched between a reticulated elastic body and the permselective membrane. However, as shown in Figure 1 (1-2), it is preferable that the electrodes 3 provided on both main surfaces are each sandwiched between a reticulated elastic body 4 and a permselective membrane 2. As mentioned above, permselective membranes are made of inorganic materials and therefore are significantly more susceptible to damage than ion-exchange membranes made of organic materials. However, providing reticulated elastic bodies on both main surfaces of the permselective membrane makes it possible to uniformly distribute the pressure applied to the membrane across its entire surface without relying on the current collector structure. This reduces the likelihood of damage to the permselective membrane. Furthermore, by holding down the electrodes with a reticulated elastic body, turbulence can be created in the flow of the Li-containing liquid within the reticulated elastic body, increasing the number of times that Li ions in the liquid come into contact with the surface of the permselective membrane, which is expected to improve the efficiency of Li recovery.

[0041] When the electrodes include an electrode made of a rigid conductive perforated plate as an electrode other than at least one of the porous electrode or membrane electrode, an embodiment shown in Figure 2 (2-1) includes an electrode 3 made of a porous electrode or membrane electrode provided on one main surface of the permselective membrane 2, and an electrode 5 made of a rigid conductive perforated plate provided on the other main surface.

[0042] 2(2-2) to (2-3) also show an embodiment in which a porous body electrode or membrane electrode 3 and a rigid conductive perforated plate 5 are provided on one main surface of the permselective membrane 2. In this case, the rigid conductive perforated plate 5 is preferably provided so as to sandwich the porous body electrode or membrane electrode 3 and the reticular elastic body 4. That is, the porous body electrode or membrane electrode 3, the reticular elastic body 4, and the rigid conductive perforated plate 5 are preferably provided in this order when viewed from one main surface of the permselective membrane 2. This embodiment makes it easier to fix not only the permselective membrane but also the porous body electrode or membrane electrode in contact with the permselective membrane while suppressing damage to these electrodes, and also makes it easier to suppress local stress. 2(2-4), there is also an embodiment in which a porous body electrode or membrane electrode 3 and a rigid conductive perforated plate 5 are provided on both main surfaces of the permselective membrane 2. In this case, the relative positions of the porous body electrode or membrane electrode 3, the reticulated elastic body 4, and the rigid conductive perforated plate 5 are the same as those in FIG. 2(2-2) to (2-3), and the rigid conductive perforated plate 5 is provided so as to sandwich the porous body electrode or membrane electrode 3 and the reticulated elastic body 4. In other words, it is preferable that the porous body electrode or membrane electrode 3, the reticulated elastic body 4, and the rigid conductive perforated plate 5 are provided in this order when viewed from one main surface of the permselective membrane 2.

[0043] [Li recovery device] The Li recovery device of this embodiment includes a Li ion recovery electrolytic cell having the Li ion recovery member of this embodiment and recovering Li ions by electrodialysis. The Li recovery device can recover Li ions from a source solution containing Li ions by using the Li ion recovery electrolytic cell having the Li ion recovery member of this embodiment.

[0044] (Li-ion recovery electrolytic cell) A preferred example of the Li-ion recovery electrolytic cell used in this embodiment is an electrolytic cell that includes, for example, a treatment tank that stores a stock solution containing Li ions and a recovery solution that recovers Li ions from the stock solution, and the Li-ion recovery member of this embodiment, in which the stock solution and the recovery solution are stored separated by the Li-ion recovery member, and in which Li ions are transferred from the stock solution to the recovery solution through the selectively permeable membrane of the Li-ion recovery member, thereby recovering the Li ions in the recovery solution.

[0045] Regarding the raw liquid and recovered liquid stored in the treatment tank being separated by a Li-ion recovery member, a single treatment tank may be divided by the Li-ion recovery member into a raw liquid tank for storing the raw liquid and a recovered liquid tank for storing the recovered liquid, or the raw liquid tank and recovered liquid tank may be connected so as to be separated by the Li-ion recovery member. Furthermore, the separation of the raw solution and the recovered solution by the Li-ion recovery member means that the Li-ion recovery member is provided so that the raw solution is stored on one main surface side of the permselective membrane and the recovered solution is stored on the other main surface side, whereby Li ions in the raw solution are recovered into the recovered solution through the permselective membrane of the Li-ion recovery member.

[0046] In this embodiment, the pH of the stock solution may be controlled. By controlling the pH, Li can be efficiently recovered regardless of the type of stock solution. In this case, although it depends on the type of stock solution, it is preferable to adjust the pH to a range of 9 to 15. Note that a pH of 9 to 15 is an adjustment target. In this embodiment, a pH of 9 to 15 includes a value of 8.5 to less than 9.5 for the stock solution, and a pH of 15 includes a value of 14.5 to less than 15.5 for the stock solution, and essentially means a range of 8.5 to less than 15.5.

[0047] In this embodiment, the pH of the raw solution may be controlled by any method, for example, by adding an alkaline aqueous solution to the raw solution. The pH of the raw solution may be controlled when recovering Li ions into the recovery solution, i.e., the pH of the raw solution may be controlled while recovering Li ions into the recovery solution, or may be controlled in advance before recovering Li ions into the recovery solution.

[0048] Preferred examples of alkaline components of the alkaline aqueous solution used to adjust the pH of the stock solution include sodium hydroxide, lithium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, tetramethylammonium hydroxide, tetraethylammonium hydroxide, calcium hydroxide, barium hydroxide, europium(II) hydroxide, thallium(I) hydroxide, and guanidine. These alkaline components may be used alone or in combination of two or more. Among these, sodium hydroxide is more preferred from the viewpoint of being able to quickly adjust the pH of the lithium ion extract.

[0049] A preferred example showing a specific embodiment of the Li-ion recovery electrolytic cell is shown in FIGS. The Li-ion recovery electrolytic cell 10 shown in Fig. 4 shows a cross section of one bipolar electrolyte cell (unit cell), and a plurality of such cells may be used in combination. The Li-ion recovery electrolytic cell 10 shown in Figs. 5 and 6 shows an embodiment having a plurality of Li-ion recovery members 1. For example, as shown in Fig. 4, by combining multiple cells each having one Li-ion recovery member 1, or by incorporating multiple Li-ion recovery members 1 into one cell, it is possible to accommodate larger sizes even if each permselective membrane is small, and it is also possible to combine the required number of cells according to the desired scale, making it easier to accommodate. Also, the Li-ion recovery electrolytic cell 10 shown in Figs. 4 to 6 can be used in either a monopolar or bipolar system.

[0050] Figure 4 shows a cross-section of the electrolytic cell 10 having the Li-ion recovery member 1 of the present embodiment shown in (2-4) of FIG. 2, together with the Li-ion recovery member shown in (2-4) of FIG. 2 having the selective permeation membrane 2, one electrode (porous electrode or membrane electrode) 3, the net-like elastic body 4, and the electrode (rigid conductive porous plate) 5. The electrolytic cell frame 11, the back partitions 12a and 12b, the packing 13, and the ribs 14a and 14b are provided. The two electrolytic cell frames 11a and 11b are combined via the packing 13 and the selective permeation membrane 2 to form a Li-ion recovery electrolytic cell (one cell). Further, it has an anode chamber 6a as a stock solution tank for storing the stock solution and a cathode chamber 6b as a recovery solution tank for storing the recovery solution.

[0051] FIGS. 5 and 6 show a cross-section of the Li-ion recovery electrolytic cell 10 having a plurality of the Li-ion recovery members 1 shown in FIGS. 1 and 2 (in FIG. 6, only the portion of the Li-ion recovery member 1 in the Li-ion recovery electrolytic cell 10 is shown). A configuration is shown in which a plurality of Li-ion recovery members 1 are provided and connected such that the main surface of the selective permeation membrane of one Li-ion recovery member faces the main surface of the selective permeation membrane of another Li-ion recovery member. FIG. 5 shows the Li-ion recovery electrolytic cell 10 shown in FIG. 4, in which a plurality of electrolytic cells 10 are connected without back partitions except at both ends. The anode chamber 6a and the cathode chamber 6b containing the stock solution and the recovery solution are alternately formed by two electrodes (rigid conductive porous plates) 5. The Li-ion recovery electrolytic cell 10 shown in FIG. 5 is a preferable configuration because a certain capacity can be ensured in the anode chamber 6a and the cathode chamber 6b by the two electrodes (rigid conductive porous plates) 5. Also, a configuration in which a plurality of the Li-ion recovery members 1 in FIG. 4 are provided via a net-like elastic body as shown in FIG. 6 is also possible. The plurality of Li-ion recovery members are fixed by the ribs 14 such that the members at both ends thereof are surrounded by the electrolytic cell frame 11 and the back partition 12. In the case of FIG. 6, the stock solution and the recovery solution are held in the portion of the net-like elastic body 4 surrounded by the selective permeation membrane 2.

[0052] The electrolytic cell frame 11 can be considered the frame of one cell, and is also called a unit cell frame. It may be made of a metal such as carbon steel, or, since it is expected to be used in an alkaline atmosphere due to the raw solution containing Li ions to be treated in the electrolytic cell, it may be made of reinforced plastic that is resistant to alkalis. The rear partition wall 12 is provided to separate adjacent cells when a plurality of electrolytic cells shown in FIG. 4 are used in combination, and is made of a metal such as Ti, which is resistant to alkali.

[0053] In the bipolar type, when electricity is supplied from an adjacent cell through the rear partition wall 12a, it is supplied from the rib 14a through the rear partition wall 12a to the electrodes 3 and 5. Since the electrode to which electricity is supplied functions as the anode, in this case the area partitioned by the rear partition wall 12a, electrolytic cell frame 11a, and permselective membrane 2 becomes the anode chamber 6a, and the electrodes 3 and 5 present in the anode chamber 6a function as anodes. A stock solution containing Li ions is stored in the anode chamber 6a. On the other hand, the area partitioned by the electrolytic cell frame 11b, rear partition wall 12b, and permselective membrane 2 forms the cathode chamber 6b, and the electrodes 3 and 5 present in the cathode chamber 6b function as cathodes. A recovery solution is stored in the cathode chamber 6b, and by applying a voltage to the electrodes and performing electrodialysis, Li ions contained in the raw solution migrate from the raw solution to the recovery solution via the permselective membrane, allowing the Li ions to be recovered in the recovery solution. Therefore, the anode chamber 6a can be referred to as the raw solution tank, and the cathode chamber 6b can be referred to as the recovered solution tank.

[0054] 4 and 5, the raw solution and the recovered solution are supplied to the anode chamber 6a and the cathode chamber 6b through piping, respectively, and Li ions in the raw solution are recovered into the recovered solution through the permselective membrane 2 of the Li ion recovery member. If necessary, piping may be provided for recovering the raw solution and the recovered solution from the anode chamber 6a and the cathode chamber 6b, respectively, as shown in FIG.

[0055] The Li recovery apparatus of this embodiment is not particularly limited as long as it includes a Li-ion recovery electrolytic cell having the Li-ion recovery member configured as described above, but specifically, it preferably includes the Li-ion recovery electrolytic cell connected to the anode chamber, a pipe for supplying the raw solution to the anode chamber, a pipe for discharging the raw solution from the anode chamber, a discharge pipe for exhausting gases such as oxygen produced by electrodialysis, a pipe for supplying a recovery solution (such as newly supplied water) to the cathode chamber, a pipe for discharging the recovery solution from the cathode chamber after recovering Li ions, and a recovery pipe for recovering gases such as hydrogen produced by electrodialysis. Furthermore, the Li recovery apparatus of this embodiment preferably includes a storage tank for the raw solution and a storage tank for the recovered solution to be supplied to the Li-ion recovery electrolytic cell, a raw solution waste tank for when the raw solution is discharged, a recovered solution waste tank for when the recovered solution is discharged, an extraction / crystallization apparatus for recovering Li from the recovery solution containing Li ions recovered from the raw solution, and these devices are connected to the Li-ion recovery electrolytic cell by the above-mentioned pipes, etc.

[0056] The storage tanks for the raw solution and the recovered solution each preferably have an agitator. By agitating the raw solution and the recovered solution circulating through the piping in each storage tank with the agitator, Li ions can be recovered more efficiently.

[0057] The Li recovery device of this embodiment may include a means for circulating the stock solution and the recovered solution. This allows for more efficient recovery of Li ions. For example, as shown in FIG. 6, a means may be employed for circulating the stock solution by supplying the stock solution to the anode chamber of the Li ion recovery electrolytic cell via a stock solution storage tank and discharging the stock solution from the anode chamber, or for supplying the recovered solution to the cathode chamber of the Li ion recovery electrolytic cell via a recovery solution storage tank and discharging the recovered solution from which Li ions have been recovered from the cathode chamber. The circulation can be performed, for example, by using a pump and turning the pump on and off manually or automatically, and may be performed continuously as a flow-through system or intermittently as a batch system. From the viewpoint of improving work efficiency, automatic operation is preferred.

[0058] As described above, in order to control the pH of the stock solution, a means for adding an alkaline aqueous solution to the stock solution may be provided. The means may be any means that allows the addition to be performed manually or automatically, continuously or intermittently, and may be provided in, for example, a stock solution storage tank. From the viewpoint of work efficiency, it is preferable to provide a means that allows the addition to be performed automatically.

[0059] The raw liquid used in the Li recovery device can be a Li ion extract extracted from a processing component of a lithium secondary battery. There are no particular limitations on the Li ion extract as long as it is extracted from a processing component, but examples include an extract extracted from a processing component of a lithium secondary battery containing a sulfide-based solid electrolyte, i.e., a Li ion extract containing a sulfide-based solid electrolyte.

[0060] The Li recovery apparatus of this embodiment may optionally include a solid-liquid separator or the like for separating Li from water and the like produced by the extraction and crystallization of Li from the recovery solution. The apparatus may also include a dryer for drying Li (e.g., the above-mentioned lithium carbonate and lithium hydroxide monohydrate) separated by the solid-liquid separator or the like. [Explanation of symbols]

[0061] 1. Li-ion recovery material 2.Selectively permeable membrane 3. First electrode (porous electrode or membrane electrode) 4.Reticulated elastic body 5. Electrode (rigid conductive perforated plate) 6a. Raw solution tank (anode chamber) 6b. Recovery liquid tank (cathode chamber) 10. Lithium recovery electrolytic cell 11a, 11b. Electrolytic cell frame 12a, 12b. Rear bulkhead 13. Packing 14a, 14b. Ribs 21.Selective permeation membrane unit 22.Adhesive part 23. Current collector

Claims

1. The device comprises a selectively permeable membrane containing an inorganic Li ion conductor, an electrode, and a reticular elastic body, the electrode is provided on at least one main surface of the permselective membrane, At least one of the electrodes is a porous electrode or a membrane electrode, The mesh elastic body has insulating properties, the porous electrode or membrane electrode is sandwiched between the reticulated elastic body and the selectively permeable membrane; Li-ion recovery component.

2. The Li ion recovery member according to claim 1 , wherein the porous electrode or the membrane electrode is provided on both main surfaces of the permselective membrane.

3. The Li ion recovery member according to claim 1 or 2, further comprising an electrode made of a metal plate having an opening.

4. The Li ion recovery member according to claim 3 , wherein the porous electrode or the membrane electrode is provided on one main surface side of the permselective membrane, and the metal plate having the opening is provided on the other main surface.

5. The Li ion recovery member according to claim 3 , wherein the porous electrode or the membrane electrode and the metal plate having the openings are provided on one main surface side of the permselective membrane.

6. The Li ion recovery member according to claim 3 , wherein the porous electrode or the membrane electrode and the metal plate having the opening are provided on both main surfaces of the permselective membrane.

7. 7. The Li ion recovery member according to claim 5, wherein the metal plate having the opening is provided so as to sandwich the porous electrode or membrane electrode and the reticulated elastic body.

8. the permselective membrane comprises a plurality of permselective membrane units and adhesive portions arranged on the same surface; The adhesive portion is provided in a lattice or honeycomb shape, The Li ion recovery member according to any one of claims 1 to 7, wherein the plurality of permselective membrane units are arranged in areas partitioned by the adhesive portions and are bonded to one another by the adhesive portions.

9. The Li ion recovery member according to claim 8 , wherein a current collector is provided at the adhesive portion.

10. The Li ion recovery member according to any one of claims 1 to 9, wherein the Li ion conductor contains an oxide or oxynitride containing Li.

11. The Li ion recovery member according to any one of claims 1 to 10, wherein the reticulated elastic body is an insulating elastic mat.

12. The Li ion recovery member according to claim 11, wherein the insulating elastic mat is a nonwoven fabric or a separator.

13. The Li ion recovery member according to claim 12, wherein the nonwoven fabric is made of plant fibers, animal fibers, mineral fibers, or chemical fibers.

14. The Li ion recovery member according to claim 12 or 13, wherein the separator is formed from a polyolefin resin or a urethane resin.

15. A Li recovery device comprising a Li ion recovery electrolytic cell having the Li ion recovery member according to any one of claims 1 to 14 and recovering Li ions by electrodialysis.

16. The Li recovery device according to claim 15, wherein the Li ion recovery members are provided in a plurality of types, and the plurality of Li ion recovery members are connected so that a main surface of a selective permeable membrane of one Li ion recovery member faces a main surface of a selective permeable membrane of another Li ion recovery member.

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