JP2022001341A - Lithium ion permselective membrane, lithium ion recovery apparatus and lithium-including compound recovery apparatus using the membrane, and lithium ion recovery method - Google Patents

Abstract

To provide a lithium ion permselective membrane excellent in film depositability and Li+ selection characteristic, lithium ion recovery apparatus and lithium-including compound recovery apparatus superior in Li+ selection characteristic, and lithium ion recovery method.SOLUTION: There are provided a lithium ion permselective membrane including a lithium ion conductive body and a specific polymer (B) having an anionic group, a lithium ion recovery apparatus and lithium-including compound recovery apparatus using the above membrane and a lithium ion recovery method.SELECTED DRAWING: Figure 1

Description

The present invention relates to a lithium ion selective transmission membrane. The present invention also relates to a lithium ion recovery device and a lithium-containing compound recovery device using this film, and a method for recovering lithium ions.

Electric vehicles are becoming more widespread because they have less environmental impact than gasoline and diesel vehicles. Large lithium (Li) ion batteries mounted on electric vehicles may be collectively referred to as "lithium or the like" by combining lithium-containing compounds such as _{Li 2} CO _{3 (hereinafter, lithium-containing compounds, lithium atoms and / or lithium ions).} There is.) Is used. Lithium atoms are also used in the artificial production of tritium, which is the fuel for fusion reactors. Therefore, the demand for lithium atoms and lithium-containing compounds is increasing rapidly.

A large amount of lithium etc. exists on the earth. However, there is a bias in the areas where lithium and the like are buried underground. On the other hand, lithium and the like are contained in a large amount in seawater, and the content of lithium and the like in the seawater is enormous with respect to the reserves of lithium and the like in the ground. In addition, lithium and the like are also contained in "nigari" used for making tofu, an electrolytic solution of a used lithium ion battery, a concentrated solution discharged during desalination of seawater, and the like. However, each lithium-containing liquid such as seawater, bittern, electrolytic solution, and concentrated liquid contains not only lithium (ion) but also other metals (ions) such as potassium, sodium, and calcium. Therefore, in order to recover lithium and the like from the above-mentioned lithium-containing liquid, a film for separating lithium ions from other metal ions (hereinafter referred to as a lithium ion separation film) is being developed.

For example, in Patent Document 1, resin particles and solid electrolyte particles having lithium ion conductivity are arranged on one layer on the same surface and heated to a temperature equal to or higher than the melting point of the resin to form a part of the solid electrolyte particles as a film. The exposed membranes are described on both sides of the. It is said that this membrane can selectively permeate lithium ions. Further, although the required characteristics are different from those of the lithium ion separation film, examples of the sheet that conducts lithium ions include a solid electrolyte sheet applied to the production of a solid electrolyte layer of a solid secondary battery. For example, in Patent Document 2, a composition obtained by dispersing a solid electrolyte having lithium ion conductivity and a binder in a dispersion medium containing a fluorine-based solvent is applied onto a substrate and heat-treated. The solid electrolyte sheet obtained is described.

Japanese Unexamined Patent Publication No. 2017-21066 Japanese Unexamined Patent Publication No. 2010-146823

A membrane that selectively permeates lithium ions (hereinafter referred to as "lithium ion selective permeation membrane") is used to quickly recover lithium ions (hereinafter, also referred to as ^{"Li +") with higher selectivity.} The characteristics of are required. Further, it is desirable that the lithium ion selective permeable film can maintain the shape of the film by binding the lithium ion conductors to each other, that is, has a film forming property. Having the above-mentioned film-forming property makes it possible to reduce the voids between the lithium ion conductors (for example, shorten the distance between the lithium ion conductors), thereby improving the permeability of lithium ions per unit film area. It is possible. However, for the membrane described in Patent Document 1 and the sheet described in Patent Document 2, let's prepare a membrane and a sheet having excellent lithium ion selectivity and recovery rate (recovery rate), which are necessary characteristics as a lithium ion selective transmission membrane. When, the film forming property is inferior.

The present invention has excellent film-forming properties and lithium ion selective transmission excellent in both lithium ion selectivity and recovery speed (hereinafter, these two characteristics are collectively ^{referred to as "Li + selective characteristics").} The subject is to provide a membrane. Another object of the present invention is to provide a lithium ion recovery device and a lithium-containing compound recovery device having excellent ^{Li + selection characteristics, and a method for recovering lithium ions.}

In view of the above problems, the present inventor has made a diligent study and found that a lithium ion conductor (A) is combined with a polymer (B) having a specific structural unit having an anionic group having a lithium ion as a counter cation. It has been found that a film can be formed when used, and that the obtained film is ^{excellent in the above-mentioned film forming property and Li + selection property.} The present invention has been further studied based on these findings and has been completed.

上記式中、Ｌ^１及びＬ^２は各々独立に置換基を有していてもよいアルキレン基を示し、Ｒ^１〜Ｒ^３は各々独立に水素原子又はアルキル基を示し、Ａは−ＮＲ^４−、−Ｏ−又は−Ｓ−を示し、Ｒ^４は水素原子又はアルキル基を示し、Ｙ^Ｂ１は対イオンとしてリチウムイオンを有するアニオン性基を示す。＊はポリマーの構造単位としての結合部位を示す。
＜２＞
上記一般式（Ｂ１）で表される構造単位のＳＰ値が１４以上２４以下である、＜１＞に記載のリチウムイオン選択透過膜。
＜３＞
上記一般式（Ｂ１）で表される構造単位が下記一般式（Ｂ２）で表される構造単位である、＜１＞又は＜２＞に記載のリチウムイオン選択透過膜。

上記式中、Ｌ^２１及びＬ^２２は各々独立に炭素数１〜７のアルキレン基を示し、Ｒ^２１〜Ｒ^２３は各々独立に水素原子又は炭素数１〜４のアルキル基を示し、Ｙ^Ｂ２は上記Ｙ^Ｂ１と同義である。＊はポリマーの構造単位としての結合部位を示す。
＜４＞
上記アニオン性基が−ＳＯ_３ ⁻Ｌｉ^＋である、＜１＞〜＜３＞のいずれか１つに記載のリチウムイオン選択透過膜。
＜５＞
上記ポリマー（Ｂ）とは異なる非水溶性ポリマー（Ｃ）であって、シアノ基、アミド基、アミノ基、ヒドロキシ基、スルファニル基、エーテル結合、スルフィド結合及びウレタン結合のうちのいずれか１種以上を有し、かつ、ガラス転移温度が０℃以下である非水溶性ポリマー（Ｃ）を含有する、＜１＞〜＜４＞のいずれか１つに記載のリチウムイオン選択透過膜。
＜６＞
＜１＞〜＜５＞のいずれか１つに記載のリチウムイオン選択透過膜を有する、リチウムイオン回収装置。
＜７＞
＜６＞に記載のリチウムイオン回収装置を備える、リチウム含有化合物回収装置。
＜８＞
＜１＞〜＜５＞のいずれか１つに記載のリチウムイオン選択透過膜を用いてリチウムイオンを回収することを含む、リチウムイオンの回収方法。 The above problems have been solved by the following means.
<1>
A lithium ion selective permeable membrane containing a lithium ion conductor (A) and a polymer (B) having a structural unit represented by the following general formula (B1).

In the above formula, L ¹ and L ² each independently represent an alkylene group which may have a substituent, R ^{1 to} R ³ each independently represent a hydrogen atom or an alkyl group, and A is −NR ⁴ −. , -O- or -S-, R ⁴ represents a hydrogen atom or an alkyl group, and Y ^B1 represents an anionic group having a lithium ion as a counter ion. * Indicates the binding site as a structural unit of the polymer.
<2>
The lithium ion selective transmission membrane according to <1>, wherein the SP value of the structural unit represented by the general formula (B1) is 14 or more and 24 or less.
<3>
The lithium ion selective permeable membrane according to <1> or <2>, wherein the structural unit represented by the general formula (B1) is the structural unit represented by the following general formula (B2).

In the above formula, L ²¹ and L ²² each independently represent an alkylene group having 1 to 7 carbon atoms, R ^{21 to} R ²³ each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and Y ^B2 is It is synonymous with the above Y ^B1. * Indicates the binding site as a structural unit of the polymer.
<4>
The lithium ion selective permeable membrane according to any one of <1> to <3>, wherein the anionic group is −SO ₃ ⁻ Li ^+.
<5>
A water-insoluble polymer (C) different from the above polymer (B), which is one or more of a cyano group, an amide group, an amino group, a hydroxy group, a sulfanyl group, an ether bond, a sulfide bond and a urethane bond. The lithium ion selective permeable film according to any one of <1> to <4>, which comprises a water-insoluble polymer (C) having a glass transition temperature of 0 ° C. or lower.
<6>
A lithium ion recovery device having the lithium ion selective permeation membrane according to any one of <1> to <5>.
<7>
A lithium-containing compound recovery device comprising the lithium ion recovery device according to <6>.
<8>
A method for recovering lithium ions, which comprises recovering lithium ions using the lithium ion selective permeation membrane according to any one of <1> to <5>.

In the present specification, unless otherwise specified, when there are a plurality of substituents, linking groups, structural units, etc. (hereinafter referred to as substituents, etc.) represented by a specific code or formula, or when there are a plurality of substituents, etc. at the same time. Alternatively, when specified alternately, the respective substituents and the like may be the same or different from each other. This also applies to the regulation of the number of substituents and the like.
As used herein, the "group" of each group described as an example of each substituent is used to include both an unsubstituted form and a form having a substituent. For example, "alkyl group" means an alkyl group which may have a substituent. Further, when the carbon number of the group is limited, the carbon number of this group means the total carbon number including the substituent unless otherwise specified.
In the present invention, the term "compound" is used to include not only the compound itself, but also a salt thereof and an ion thereof. Further, it is meant to include a structure in which a part of the structure is changed as long as the effect of the present invention is not impaired. Further, the compound for which substitution or non-substitution is not specified may have any substituent as long as the effect of the present invention is not impaired. This also applies to substituents and linking groups.
As used herein, the term "(meth) acrylate" is used to include both acrylate and methacrylate. This also applies to "(meth) acrylic acid", "(meth) acrylamide", "(meth) acrylonitrile" and "(meth) acryloyl group".
The numerical range represented by using "~" in the present specification means a range including the numerical values before and after "~" as the lower limit value and the upper limit value.
In the present specification, the SP value is described by omitting the ^{unit (cal / cm 3} ) ^1/2.

The lithium ion selective transmission film of the present invention is excellent in film formation property, and ^{is also excellent in lithium ion selectivity and recovery speed (Li +} selective property). Further, the lithium ion recovery device, the lithium-containing compound recovery device, and the lithium ion recovery method of the present invention make it possible to recover lithium ions or lithium-containing compounds with excellent recovery speed and excellent selectivity. ..

FIG. 1 is a schematic diagram of a lithium ion recovery device according to an embodiment of the present invention. FIG. 2 is a schematic diagram of a lithium-containing compound recovery device according to an embodiment of the present invention.

<Lithium ion selective transmission membrane>
The lithium ion selective permeation film of the present invention has a lithium ion conductor (A) and a polymer (B) having a structural unit represented by the following general formula (B1) (hereinafter, also simply referred to as “polymer (B)”. ) And. The form of the lithium ion selective transmission film of the present invention may be any form as long as it has film forming properties and has lithium ion conductivity. Both the lithium ion conductor (A) and the polymer (B) constituting the lithium ion selective transmission film of the present invention have lithium ion conductivity. Therefore, one form of the membrane includes a form in which the lithium ion conductor (A) is dispersed in the polymer (B) (for example, a form of a composite membrane). This variance may be random, regular, or the like.
Since the lithium ion selective transmission film of the present invention has the above structure, it is excellent in film formation property, lithium ion selectivity and recovery speed. The reason for this is not clear, but it is presumed as follows.
Polymer (B), lithium ion (hereinafter, "Li ^+" and also referred.) An anionic group to counter cation ^to, -L 1 ^{-A-L 2} - in particular chain length or more linking groups represented It has a specific structural unit that it has on the carbon chain via. Since the polymer (B) has this anionic group, in the lithium ion selective transmission film of the present invention, the lithium ion conductor (A) having high lithium ion selectivity is dispersed in the polymer (B) and ion conduction is performed. The body (A) and the polymer (B) interact with each other to sufficiently bind the lithium ion conductors (A) to each other, and further, the adhesion between the lithium ion conductor (A) and the polymer (B) is improved. It is considered that the film can be improved and the film forming property is excellent. Moreover, since the anionic group in the polymer (B) is bonded to the carbon chain via a linking group having a specific chain length or longer as described above, it has appropriate motility. Therefore, the polymer (B) not only does not inhibit the ion conductivity of the coexisting lithium ion conductor (A), but can also reinforce the lithium ion conductivity of the lithium ion conductor (A) by the lithium ion conductivity exhibited by itself. .. As a result, it is considered that the lithium ion selective permeation film of the present invention has enhanced lithium ion permeability and exhibits an excellent lithium ion recovery rate.

The film thickness of the lithium ion selective permeation membrane of the present invention can be appropriately selected depending on the desired embodiment, the size of the device to be incorporated, and the like. For example, it is 1 to 1000 μm and may be 10 to 500 μm.
The lithium ion selective transmission membrane of the present invention may have a support and a substrate. Since the lithium ion selective permeation film of the present invention has excellent film forming properties, it can be handled by itself without using a support and a substrate.
When the lithium ion selective permeable membrane of the present invention is incorporated into a lithium ion recovery device or a lithium-containing compound recovery device, the membrane area can be appropriately selected according to a desired embodiment, the size of the device to be incorporated, and the like. .. For example, it is 0.5 to 500,000 cm ² , and may be 1 to ^{100,000 cm 2.}

(Lithium-ion conductor (A))
The lithium ion conductor (A) used in the present invention is a compound that exhibits lithium ion conductivity (conducts lithium ions and is difficult (preferably not) to conduct other metal ions such as potassium and sodium). If there is, there is no particular limitation. Further, the lithium ion conductor (A) preferably has resistance to a lithium-containing liquid and a recovered liquid described later (for example, “water-insoluble” described later). Specific examples of the lithium ion conductor (A) include an oxide-based inorganic solid electrolyte. The oxide-based inorganic solid electrolyte is preferably a compound containing an oxygen atom and having lithium ion conductivity.
Since the lithium ion conductor (A) used in the present invention is a solid in a steady state, it is usually not dissociated or liberated into cations and anions. In this respect, it is clearly distinguished from lithium salts in which cations and anions are dissociated or liberated in water or polymers. That is, the lithium ion conductor (A) is used in the sense that it does not contain a lithium salt. Here, the lithium salt refers to a low molecular weight inorganic or organic lithium salt compound (for example, CF ₃ SO ₃ Li used in Test No. c11 of Examples described later).

Specific examples of the compound include, for example, Li _xa La _ya TiO ₃ [xa = 0.3 to 0.7, ya = 0.3 to 0.7] (LLT), Li _xb La _yb Zr _zb M ^bb _mb O. _nb (M ^bb is at least one element of Al, Mg, Ca, Sr, V, Nb, Ta, Ti, Ge, In, Sn, xb satisfies 5 ≦ xb ≦ 10, and yb is 1 ≦ yb. ≦ 4 is satisfied, zb is 1 ≦ zb ≦ 4, mb is 0 ≦ mb ≦ 2, nb is 5 ≦ nb ≦ 20), Li _{xc Byc} M ^cc _{zc Onc} (M ^cc is). At least one element of C, S, Al, Si, Ga, Ge, In, Sn, xc satisfies 0 <xc ≦ 5, yc satisfies 0 <yc ≦ 1, and zc satisfies 0 <zc ≦. met 1, nc satisfies _{0 <nc ≦ 6.),} Li xd (Al, Ga) yd (Ti, Ge) zd Si ad P md O nd ( provided that, 1 ≦ xd ≦ 3,0 ≦ yd ≦ 1 , 0 ≦ zd ≦ 2,0 ≦ ad ≦ 1,1 ≦ md ≦ 7,3 ≦ nd ≦ 13), the number of ^{_{Li (3-2xe) M ee xe D}} ee O (xe 0 to 0.1 ^{M ee} represents a divalent metal atom. D ^ee represents a halogen atom or a combination of two or more kinds of halogen atoms), Li _xf Si _{yf Ozf} (1 ≦ xf ≦ 5, 0 <yf ≦ 3). _{, 1 ≦ zf ≦ 10),} Li xg S yg O zg (1 ≦ xg ≦ 3,0 <yg ≦ 2,1 ≦ zg ≦ 10), Li 3 BO 3 -Li 2 SO 4, Li 2 O-B 2 O _3- P ₂ O ₅ , Li ₂ O-SiO ₂ , Li ₆ BaLa ₂ Ta ₂ O ₁₂ , Li ₃ PO _{(4-3 / 2w)} N _w (w is w <1), LISION (Lithium superionic compound) ) Li _3.5 Zn _0.25 GeO _{4 with} a perovskite type crystal structure, La _0.55 Li _0.35 TiO _{3 with a perovskite type crystal structure, LiTi 2} P ₃ with a NASICON (Naturium super ionic compound) type crystal structure. O ₁₂ , Li _{1 + xh + yh} (Al, Ga) _xh (Ti, Ge) _2-xh Si _yh P _3-yh O ₁₂ (however, 0 ≦ xh ≦ 1, 0 ≦ yh ≦ 1), Li having a garnet-type crystal structure ₇ La ₃ Zr ₂ O ₁₂ (LLZ) and the like can be mentioned. Phosphorus compounds containing Li, P and O are also desirable. For example, lithium phosphate (Li ₃ PO ₄ ), LiPON in which a part of oxygen of lithium phosphate is replaced with nitrogen, LiPOD ¹ (D ¹ is Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zr. , Nb, Mo, Ru, Ag, Ta, W, Pt, Au and the like) and the like. Further, LiA ¹ ON (A ¹ is at least one of Si, B, Ge, Al, C, Ga and the like) and the like can also be preferably used.

The lithium ion conductor (A) is preferably particles. In this case, the median diameter D50 of the lithium ion conductor particles is not particularly limited, but is preferably 30 μm or less, more preferably 20 μm or less, and further preferably 15 μm or less in order to improve the film strength. preferable. The lower limit is preferably 0.1 μm or more, more preferably 0.3 μm or more, and further preferably 0.6 μm or more.
The lithium ion conductor (A) preferably has a particle size that does not change significantly before and after the formation of the lithium ion selective transmission film, and is dispersed in the polymer (B) after the film formation. Therefore, it is preferable to use the particulate lithium ion conductor (A) as a raw material for forming the lithium ion selective transmission film.
The average particle size of the particles of the lithium ion conductor (A) is measured by the following procedure. Lithium-ion conductor particles are diluted with 1% by weight of a dispersion in a 20 mL sample bottle using heptane. The diluted dispersed sample is irradiated with 1 kHz ultrasonic waves for 10 minutes, and immediately after that, it is used for the test. Using this dispersion sample, data was captured 50 times using a laser diffraction / scattering particle size distribution measuring device LA-920 (trade name, manufactured by HORIBA) using a measuring quartz cell at a temperature of 25 ° C. Obtain the volume average particle size. For other detailed conditions, etc., refer to the description of JIS Z 8828: 2013 "Particle size analysis-Dynamic light scattering method" as necessary. Five samples are prepared for each level and the average value is adopted.

The lithium ion selective transmission film of the present invention may contain one type of lithium ion conductor (A) or may contain two or more types.
The content of the lithium ion conductor (A) in the lithium ion selective permeation film of the present invention is preferably 20% by mass or more, preferably 30% by mass, based on the total solid content in order to improve the recovery rate and selectivity of lithium ions. The above is more preferable, and 40% by mass or more is further preferable. The upper limit is preferably 90% by mass or less, more preferably 80% by mass or less, in terms of film forming property.
In the present invention, the solid content is a component remaining in the membrane when it is air-dried at 50 ° C. for 5 hours and vacuum-dried at 100 ° C. for 5 hours to form a lithium ion selective permeable membrane, specifically, a solvent described later. Means ingredients other than.

(Polymer having a structural unit represented by the formula (B))
The polymer having a structural unit represented by the following general formula (B) is a polymer in which the counter cation in the anionic group is a hydrogen atom or an alkali metal ion, and the counter cation is limited to the lithium ion, that is, the lithium ion of the present invention. It includes a polymer (B) which is a constituent material of a selective transmission film and a polymer (b) whose counter cation is limited to sodium ion or potassium ion.
The type of the polymer having the structural unit represented by the following general formula (B) is not particularly limited as long as it has the following structural unit, but it exhibits high flexibility and can realize the above-mentioned action and effect at a high level. In that respect, (hydrogenated) aliphatic hydrocarbon polymers and the like are preferable, and (hydrogenated) aliphatic acyclic hydrocarbon polymers are more preferable.
The aliphatic hydrocarbon polymer and the aliphatic acyclic hydrocarbon polymer may be saturated or unsaturated, and it is preferable that the polymer main chain is mainly formed of carbon-carbon bonds. For example, a diene polymer having a double bond in the main chain and a non-diene polymer having no double bond in the main chain can be mentioned. Specific examples thereof include polybutadiene, polyisoprene, butyl rubber, acrylonitrile-butadiene copolymer, ethylene-propylene copolymer, ethylene-propylene-diene copolymer, and hydrogen reduced products of aromatic hydrocarbon polymers described later. Be done.

In the above formula, L ¹ and L ² each independently represent an alkylene group which may have a substituent, R ^{1 to} R ³ each independently represent a hydrogen atom or an alkyl group, and A is −NR ⁴ −. , -O- or -S-, R ⁴ indicates a hydrogen atom or an alkyl group, and Y ^B is an anion having a hydrogen atom or an alkali metal ion (preferably lithium ion, sodium ion or potassium ion) as a counter ion. Indicates a sex group. * Indicates the binding site as a structural unit of the polymer.

In the present invention, the anionic group may be any group that can form an anion and impart lithium ion conductivity to the polymer itself. Such anionic groups include -C (= O) OM, -S (= O) ₂ OM, -OS (= O) ₂ OM, -P (= O) (OM) ₂ or -OP (=). O) (OM) _{2 and the} like can be mentioned.
M represents a hydrogen atom or an alkali metal ion. In the lithium ion selective permeation membrane of the present invention, the above M may or may not be dissociated (free). M is a lithium ion in the polymer (B) which is a constituent material of the lithium ion selective transmission film, and is a hydrogen atom or an alkali metal ion excluding the lithium ion in the polymer (b).
The anionic group is preferably -C (= O) OM or -S (= O) ₂ OM, and has a large ion dissociation constant of -S (= O) _{2 from the viewpoint of obtaining a better recovery rate of lithium ions.} OM is preferred.
The polymer, in the structural unit represented by the above formula (B), may have a Y ^B except Meikisuru Y ^B in the formula.
For each substituent group other than Y ^B, hereinafter described polymer (B) is a structural material of a lithium ion selective permeable membrane of the present invention.

(Polymer (B))
-Structural unit represented by Eq. (B1)-
The polymer (B) used in the present invention has a structural unit represented by the following general formula (B1). This polymer (B) has lithium ion conductivity.

In the above formula, L ¹ and L ² each indicate an alkylene group which may have a substituent independently. L number of carbon atoms of the alkylene group which may have a substituent in ^1, 1 to 10, more preferably from 1 to 7, more preferably 1 to 5, particularly preferably 1 to 3, 1 or 2 Most preferred. L number of carbon atoms of the alkylene group which may have a substituent in ² to 10, more preferably from 1 to 7, more preferably 1 to 5, 1 to 3 is most preferred.
The ^{substituent that L 1} and L ² may have is not particularly limited as long as the effect of the present invention is not impaired, and examples thereof include a hydroxy group, an oxo group (= O), and Y ^B1 .
Further, the ^{alkylene group which may have a substituent in L 1} and L ² may be linear or branched, and examples thereof include a ring structure (for example, a 5- or 6-membered ring structure). The ring-constituting atom is preferably a carbon atom.). When L ¹ and L ² are alkylene groups having a ring structure, the bond constituting the ring structure is a group represented by −L ¹ −A − L ² − from the viewpoint of not impairing the motility of the anionic group. Of these, it is preferable that the atom is not in the shortest chain below, and it is more preferable that one of the atoms forming the ring structure is present as a quaternary carbon atom in the shortest chain.

R ^{1 to} R ³ each independently represent a hydrogen atom or an alkyl group. The ^{number of carbon atoms of the alkyl group in R 1 to} R ³ is preferably 1 to 4, more preferably 1 or 2, and even more preferably 1. R ¹ is preferably a hydrogen atom or methyl, and more preferably a hydrogen atom. Both R ² and R ³ are preferably hydrogen atoms.
A ^-NR 4 is -, - O-or -S- shown, ^{R 4} represents a hydrogen atom or an alkyl group. As the alkyl group in ^{R 4,} the description of the alkyl group in ^{R 1 to} R ^{3 above can be preferably applied.} R ⁴ is more preferably hydrogen atom.
A is preferably -O- or -S-, and more preferably -S-.
Y ^B1 represents an anionic group having a lithium ion as a counter cation. For preferred anionic groups, the description of anionic groups described above can be applied.
* Indicates the binding site as a structural unit of the polymer.

In the structural unit represented by the general formula (B1), ^{the chain connecting the carbon atom to which R 1} is bonded and the anionic group Y ^B1 is too long considering the ratio of the anionic group in the polymer (B). It is preferable that there is no such thing. Specifically, -L 1 ^-A-L 2 ^- Among the groups represented by the bonding number of atoms constituting the shortest chain (. Hereinafter, simply also referred to as "shortest number atoms") is preferably 10 or less, 8 The following is more preferable, 7 or less is further preferable, and 6 or less is most preferable. The lower limit of the shortest number of atoms is 3 or more, preferably 4 or more, preferably 5 or more, from the viewpoint of imparting motility to the anionic group to enhance the permeability of lithium ions and exhibiting an excellent recovery rate of lithium ions. More preferred.
For example, in the structural unit represented by the general formula (B1) possessed by the polymer (P1-1) in the examples, two carbon atoms in the ethylene group, one sulfur atom and three carbon atoms in the propylene group are used. A total of 6 is the shortest number of atoms.
Also, the side chains in the case of capturing the shortest chain as a main chain, namely L ^1, branched chain in L ^2, the bonding number of atoms constituting the longest chain of (hereinafter, simply referred to as "the number of the longest atomic". ) Is preferably 5 or less, more preferably 3 or less, and even more preferably 2 or less.

The upper limit of the SP value of the structural unit represented by the general formula (B1) improves the hydrophobicity of the structural unit having an anionic group, suppresses the permeation of hydrated ions, and makes the water permeability of the lithium ion selective membrane. From the viewpoint of suppressing, 24 or less is preferable, and 22 or less is more preferable. The lower limit of the SP value is preferably 14 or more, more preferably 16 or more. That is, the SP value is preferably 14 or more and 24 or less, and more preferably 16 or more and 22 or less.
The SP value of the structural unit represented by the general formula (B1) is obtained as follows.

[SP value calculation method]
"SP value" as used herein is a value determined by calculation using the ^{HSPiP 5 th Edition 5.0.04 (https://hansen-solubility.com/downloads.php)} . When calculating the polymer structure, both ends of the repeating unit structure are calculated as *.

-Structural unit represented by Eq. (B2)-
The structural unit represented by the general formula (B1) is preferably a structural unit represented by the following general formula (B2).

In the above formula, L ²¹ and L ²² each independently represent an alkylene group having 1 to 7 carbon atoms. The carbon number of the alkylene group in L ²¹ is preferably 1 to 5, more preferably 1 to 3, and even more preferably 1 or 2. The carbon number of the alkylene group in L ²² is preferably 1 to 5, and more preferably 1 to 3.
As the alkylene group having 1 to 7 carbon atoms in ^{L 21} and L ²² , the description other than the carbon number of the alkylene group which may have the substituent in ^{L 1} and L ^{2 can be preferably applied.}
R ^{21 to} R ²³ each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. The ^{number of carbon atoms of the alkyl group in R 21 to} R ²³ is preferably 1 or 2, and more preferably 1. R ²¹ is preferably a hydrogen atom or methyl, more preferably a hydrogen atom. Hydrogen atoms are preferable for both R ²² and R ^23.
Y ^{B2 is synonymous with Y B1} in the formula (B1) and indicates an anionic group having a lithium ion as a counter cation. For preferred anionic groups, the description of anionic groups described above can be applied.
* Indicates the binding site as a structural unit of the polymer.

-L ^{21 -S-L 22} - Of the groups represented, coupled atoms of the atoms that constitute the shortest chain (. Hereinafter, simply also referred to as "shortest number atoms") is preferably from 3 to 10. The number of bonds of the atoms constituting the longest chain among the shortest atomic number and the side chain when this shortest chain is regarded as the main chain, that is ^{, the branched chains in L 21} and L ²² (hereinafter, simply "the longest atomic number"). . the "and also referred for), -L 1 ^-A-L 2 in the general formula (B1) ^- can preferably be applied to the description of the number of shortest atoms and the number of the longest atom in the group represented by.

-Structural unit represented by equation (b1)-
The polymer (b) having an anionic group different from that of the polymer (B) has a structural unit represented by the following formula (b1).

In the above ^{formulas, L 1, L 2, R 1} ~R 3 and A have the same meanings as ^{L 1, L 2, R 1} ~R 3 and A in the formula (B1).
Y ^b1 represents an anionic group having a hydrogen atom or an alkali metal ion (preferably a sodium ion or a potassium ion) as a counter ion. However, lithium ions are not included in the alkali metal ions in ^{Y b1.} For preferred anionic groups, the description of anionic groups described above can be applied.
* Indicates the binding site as a structural unit of the polymer.

Examples of the structural unit represented by the general formulas (B), (B1) and (b1) include the following structural units. However, it is not limited to these structural units.
In the following chemical structural formula, M represents a hydrogen atom or an alkali metal ion, and corresponds to a counter cation defined by the formulas (B), (B1) and (b1), respectively. As the anionic group of the following chemical structural formula, -COOM or -SO ₃ M is shown, but a structure having -P (= O) (OM) ₂ or -OP (= O) (OM) ₂ can also be mentioned. .. * Indicates the binding site as a structural unit of the polymer.

The polymer (B) may have a structural unit (hereinafter, referred to as another structural unit) other than the structural unit represented by the general formula (B1). The other structural units are not particularly limited as long as they can be copolymerized with the structural units represented by the general formula (B1). Preferably, the structural unit capable of forming the above-mentioned aliphatic hydrocarbon polymer is mentioned, and specific examples thereof include ethylene, 1,3-butadiene, isobutylene, isoprene, acrylonitrile, 5-ethylidene-2-norbornene, and dicyclopentadiene. Examples thereof include structural units containing 1,4-hexadiene and the like as monomer components, and oxidants and hydrocarbons of these structural units.
Like the polymer (B), the polymer (b) may have a structural unit other than the structural unit represented by the general formula (b1), and the structural unit may be the other structural unit. The structural units to be described are mentioned.

The ratio of the structural unit represented by the general formula (B1) and the ratio of the structural unit represented by the general formula (B2) in the polymer (B) are not particularly limited, but are preferably 5 to 95 mol%. ~ 90 mol% is more preferable, and 20 to 80 mol% is further preferable.
The ratio of the other structural units in the polymer (B) is not particularly limited, but is preferably 5 to 95 mol%, more preferably 10 to 90 mol%, still more preferably 20 to 80 mol%.
The ratio of the structural unit represented by the above general formula (b1) in the polymer (b) is not particularly limited, but is preferably 5 to 100 mol%, more preferably 10 to 90 mol%, still more preferably 20 to 80 mol%.
The ratio of the other structural units in the polymer (b) is not particularly limited, but is preferably 0 to 95 mol%, more preferably 10 to 90 mol%, still more preferably 20 to 80 mol%.

The polymer (B) may independently have one type or two or more types of the structural unit represented by the general formula (B1) and the other structural units.
The polymer (b) may independently have one type or two or more types of the structural unit represented by the general formula (b1) and the other structural units.
The form of the polymer (B) and the polymer (b) is not particularly limited, and may be any form such as random, block and graft as long as the effect of the present invention is not impaired.

Polymers (B) and (b) differ from the above-mentioned lithium salts in that they are polymers having repeating structural units. From the above points, the number average molecular weight (Mn) of the polymers (B) and (b) is preferably 800 or more, more preferably 1000 or more, further preferably 1000 to 10000, and particularly preferably 1500 to 8000. By setting the number average molecular weight within the above preferable numerical range, the film forming property can be improved. The number average molecular weight can be measured by a known method using a gel permeation chromatograph (GPC).

The lithium ion selective transmission membrane of the present invention may contain one kind of polymer (B) or two or more kinds.
The content of the polymer (B) in the lithium ion selective permeation membrane of the present invention is preferably 5 to 50% by mass, more preferably 7 to 40% by mass, still more preferably 10 to 30% by mass, based on the total solid content. Most preferably, 15 to 25% by mass.

The terminal structures of the polymer (B) and the polymer (b) are not particularly limited, and depend on the presence or absence of other structural units, the type of substrate used at the time of synthesis, or the type of quenching agent (reaction terminator) at the time of synthesis. It is not uniquely determined. As the terminal structure, for example, a hydrogen atom, a hydroxy group, a halogen atom, an ethylenically unsaturated group, an alkyl group, an aromatic heterocyclic group (preferably a thiophene ring) or an aromatic hydrocarbon group (benzene ring is preferable). ).

Method for synthesizing polymer (B) As a method for synthesizing polymer (B), a reactive group b and an anionic group capable of reacting with a reactive group a to form a bond with a polymer having a reactive group a are used. Examples thereof include a method of reacting a compound having an anionic group to introduce an anionic group and a method of polymerizing a monomer having an anionic group to obtain a polymer. In these methods, the anionic group means an anionic group having a lithium ion as a counter cation.
Reactive group a and a reactive group b is by chemical reaction, -L 1 ^-A-L 2 ^- is a linking group or a group capable of forming a part thereof represented, those skilled in the art, the desired It can be appropriately selected to form the structure of the linking group or a part thereof.
The compound having an anionic group and the monomer having an anionic group used in these synthetic methods can be synthesized by a conventional method without particular limitation, and for example, ordinary ion exchange (lithium such as LiOH) can be synthesized. A base or ion exchange membrane can be synthesized by contacting a compound or monomer having an anionic group having a sodium ion or the like as a counter cation). As for other reaction conditions, a commonly used method can be appropriately selected.

As the polymer synthesis method itself, a commonly used method can be used, for example, radical polymerization can be mentioned, and a polymerization initiator, a reaction terminator and the like are also usually used in combination with the monomer, oligomer and the like to be used. The agent can be used as appropriate. A commercially available polymer can also be used as the polymer.

(Water-insoluble polymer (C))
From the viewpoint of imparting excellent membrane strength to the lithium ion selective permeable membrane of the present invention, it is also preferable that the lithium ion selective permeable membrane of the present invention contains a water-insoluble polymer (C). The water-insoluble polymer (C) has at least one of a cyano group, an amide group, an amino group, a hydroxy group, a sulfanyl group, an ether bond, a sulfide bond and a urethane bond, and has a glass transition temperature ( Hereinafter, it is also referred to as Tg.) It is a polymer having a temperature of 0 ° C. or lower. The polymer (C), -L 1 ^-A-L 2 ^- the anionic group through a specific chain length or more linking groups represented by having no point, the polymer (B) different from the polymer ( It is a water-insoluble polymer).
The water-insoluble property in the water-insoluble polymer (C) means that the solubility of the polymer in 100 g of water is 0.1 g or less under the condition of a liquid temperature of 25 ° C.

The water-insoluble polymer (C) may be any of a chain polymerization type polymer, a polyaddition type polymer and a polycondensation type polymer, and a chain polymerization type polymer and a polycondensation type polymer are preferable. Hereinafter, the water-insoluble polymer (C) which is a chain polymerization type polymer is referred to as "chain polymerization type polymer (C)", and the water-insoluble polymer (C) which is a polyaddition type polymer is referred to as "heavy addition type polymer (C)". ".

-Chain-growth polymer (C)-
The chain-growth polymerization type polymer (C) is a polymer obtained by chain-polymerizing one or more kinds of monomers having a non-aromatic carbon-carbon double bond. For example, vinyl polymers can be mentioned, and more specifically, (meth) acrylic polymers and hydrocarbon polymers (aliphatic hydrocarbon polymers and aromatic hydrocarbon polymers) can be mentioned. Examples of the aliphatic hydrocarbon polymer include those described in the above polymer (B), and examples of the aromatic hydrocarbon polymer include a polymer having a structural unit derived from an aromatic vinyl compound such as a styrene compound, for example, a styrene-butadiene co-weight. Coalescence is mentioned.
In the synthesis of the chain-polymerized polymer (C), a monomer for introducing any one of a cyano group, an amide group, an amino group, a hydroxy group, a sulfanyl group, an ether bond, a sulfide bond and a urethane bond (monomer (a1)). ), Examples of (meth) acrylonitrile, hydroxy group-containing (meth) acrylate (eg, hydroxyethyl (meth) acrylate), sulfanyl group-containing (meth) acrylate (eg, sulfanyl ethyl (meth) acrylate), (meth). Examples thereof include acrylamide, vinyl alcohol, allylamine, and (meth) acrylate containing a sulfide bond (for example, 2-methylthioethyl (meth) acrylate, 2- (2-ethoxyethoxy) ethyl (meth) acrylate). Of these, acrylonitrile and acrylamide are preferable, and acrylonitrile is most preferable. The monomer (a1) may be used alone or in combination of two or more.
In the synthesis of the chain polymerization type polymer (C), a copolymerization component is introduced for a structural unit having any one of a cyano group, an amide group, an amino group, a hydroxy group, a sulfanyl group, an ether bond, a sulfide bond and a urethane bond. Examples of the monomer (monomer (b1)) for this purpose include 1,3-butadiene, isoprene, and alkyl (meth) acrylates (preferably ethyl acrylates, butyl acrylates, and (2-ethylhexyl) acrylates). Of these, 1,3-butadiene, isoprene or butyl acrylate is preferable, and 1,3-butadiene or isoprene is more preferable. The monomer (b1) may be used alone or in combination of two or more.
It is also preferable to introduce an ether bond or the like by epoxidizing a natural rubber containing polyisoprene or the like.
Further, as the chain polymerization type polymer (C), a third monomer (monomer other than the above) may be used to the extent that its function is not impaired.

Among all the structural units derived from each monomer constituting the chain-growth polymerization type polymer (C), the content of the structural unit derived from the monomer (a1) is preferably 26% by mass or more, and the upper limit is preferably 70% by mass or less, preferably 60% by mass. The following is more preferable, and 50% by mass or less is particularly preferable. Further, in the case of the chain-growth polymerization type polymer (C) synthesized by epoxidation or the like with respect to the natural rubber containing the polyisoprene or the like, the structural unit having an ether bond or the like in all the structural units constituting the chain polymerization type polymer (C). The content of epoxide is preferably 26% by mass or more, the upper limit is preferably 70% by mass or less, more preferably 60% by mass or less, and particularly preferably 50% by mass or less.
The chain-growth polymerization type polymer (C) is preferably a polymer synthesized by using one kind of monomer (a1) and one kind of monomer (b1) from the viewpoint of film strength.

-Multi-addition polymer (C)-
Examples of the heavy addition polymer (C) include polyurethane and polyurea.
Specific examples of the monomer for introducing any one of a cyano group, an amide group, an amino group, a hydroxy group, a sulfanyl group, an ether bond, a sulfide bond and a urethane bond into the heavy addition type polymer (C) include 4, 4'-methylenebis (phenylisocyanate), 4,4'-methylenebis (cyclohexylisocyanate), isophorone diisosocyanate, ethylene glycol, di (propylene glycol) and tetramethylene glycol, or these monomers with cyano group, amide group, amino Examples thereof include a monomer having any one of a group, a hydroxy group, a sulfanyl group, an ether bond, a sulfide bond and a urethane bond introduced therein.

The lower limit of Tg of the water-insoluble polymer (C) is practically −60 ° C. or higher, preferably −40 ° C. or higher.
The Tg of the water-insoluble polymer (C) itself can be adjusted by the type of the monomer and the amount used in the synthesis. The form of the water-insoluble polymer (C) is not particularly limited, and includes random, block, and graft forms that can be taken by each of the above polymers.
The Tg of the water-insoluble polymer (C) is determined as follows.

[Glass-transition temperature]
Using a differential scanning calorimeter (DSC), a sample (water-insoluble polymer (C)) of about 10 mg is cooled from 30 ° C. to -50 ° C. at a temperature lowering rate of 50 ° C./min under a nitrogen atmosphere, and 15 at that temperature. Hold for minutes. The temperature is raised from −50 ° C. to 100 ° C. at a heating rate of 10 ° C./min, and the temperature is maintained for 5 minutes. Further, the temperature is cooled to −50 ° C. at a temperature lowering rate of 50 ° C./min, held at that temperature for 15 minutes, and then raised to 100 ° C. at a temperature rising rate of 10 ° C./min.
The glass transition temperature (Tg) is perceived as the DSC curve bends due to the change in specific heat and the baseline moves in parallel during the second temperature rise. The temperature at the intersection of the tangent of the baseline, which is lower than this bending, and the tangent of the point where the inclination is maximum at the bending portion is defined as the glass transition temperature (Tg).
In the literature values and catalog values, those values are adopted for polymers that deviate from the threshold value of 0 ° C. in the present invention by 40 ° C. or more. For polymers for which there is no data or polymers at around 0 ° C, the above method is used for measurement.

The lithium ion selective permeation membrane of the present invention may contain one kind of water-insoluble polymer (C) or two or more kinds.
The content of the water-insoluble polymer (C) in the lithium ion selective permeation membrane of the present invention is preferably 50% by mass or less, more preferably 45% by mass or less, still more preferably 40% by mass or less. The lower limit is preferably 1% by mass or more, more preferably 5% by mass or more.

The lithium ion selective transmission film of the present invention may contain components other than the above-mentioned lithium ion conductor (A), polymer (B) and water-insoluble polymer (C) as long as the effects of the present invention are not impaired. Examples of such a component include the ionic liquid described in International Publication No. 2017/9821.

-Manufacturing method of lithium ion selective transmission membrane-
The method for producing the lithium ion selective transmission membrane of the present invention is not particularly limited. For example, the lithium ion conductor (A), the polymer (B), and the solvent are stirred in a temperature range of 20 ° C. to the boiling point of the solvent for 1 to 5 hours, and a mixture of the lithium ion conductor (A) and the polymer (B) is mixed. To get. The lithium ion selective permeable membrane of the present invention can be obtained as a membrane by applying this mixture by a usual method and drying at 40 to 100 ° C. for 3 to 24 hours.
The solvent is not particularly limited, but a solvent having an SP value of 15 or more is preferable. Specific examples of the solvent include water, methanol, ethanol, isopropanol, acetone, methyl ethyl ketone, dimethyl sulfoxide, tetrahydrofuran, acetonitrile, ethyl acetate, dimethylacetamide, dimethylformamide, N-methyl-2-pyrrolidone, chloroform and dichloromethane. Among these, water, tetrahydrofuran, methyl ethyl ketone, dimethylacetamide, dimethylformamide and N-methyl-2-pyrrolidone are preferable. One type of solvent may be used, or two or more types may be used.

Hereinafter, the lithium ion recovery device and the lithium-containing compound recovery device of the present invention, and the lithium ion recovery method will be described.

<Lithium ion recovery device>
The lithium ion recovery device of the present invention includes the lithium ion selective permeable film of the present invention. This lithium ion recovery device is a device that recovers lithium ions from the above-mentioned lithium-containing liquid, and the lithium ion recovery method of the present invention described later can be suitably carried out.
The lithium ion recovery device 1A shown in FIG. 1 will be described below.

The lithium ion recovery device 1A includes a lithium ion selective transmission membrane 10. As shown in FIG. 1, the lithium ion recovery device 1A is arranged at a substantially U-shaped processing tank 2 and the bottom of the processing tank 2, and is a lithium ion selective transmission membrane that separates the processing tank 2 into two spaces. It is equipped with 10. The lithium ion selective transmission membrane 10 is arranged so that its edge is in contact with the inner surface of the bottom portion and separates the two spaces. Further, the lithium ion recovery device 1A has a negative electrode 4 arranged facing the lithium ion selective transmission film 10 in one space isolated from the lithium ion selective transmission film 10, and lithium ions in the other space. It has a positive electrode 3 which is arranged facing each other apart from the selective transmission film 10. The positive electrode 3 and the negative electrode 4 are electrically connected to the − terminal or the + terminal of the power supply 16 by a lead wire. Further, the processing tank 2 is equipped with a device (stirring device) having a stirring function. Specifically, the stirrer 17 arranged in the two isolated spaces in the processing tank 2 and the rotary table (driving unit and control unit) installed below the outside of the processing tank 2 to rotate each of the stirrers 17 are provided. Includes a magnetic stirrer with (including) 18.
In the lithium ion recovery device 1A, the undiluted solution 5 containing lithium ions is charged into one space (the space in which the positive electrode 3 is arranged) isolated by the lithium ion selective transmission film 10, and the other space (the negative electrode 4 is arranged). The recovery liquid 6 for recovering lithium ions from the stock solution 5 is put into the space).
As the undiluted solution 5, a solution containing other metal ions such as potassium ion and sodium ion is used in addition to lithium ion, and specifically, the above lithium-containing solution such as seawater, concentrated seawater and bittern is used. The recovery liquid 6 is preferably a liquid that does not contain lithium ions or other metal ions before starting operation as a lithium ion recovery device, and specifically, dilute hydrochloric acid and water (preferably pure water). ) Etc. can be used.

The method of recovering lithium ions by the lithium ion recovery device 1A can be performed in the same manner as the method of using a normal lithium ion separation membrane, except that the lithium ion selective transmission membrane 10 is used. Specifically, the lithium ion recovery device 1A is provided with the lithium ion selective permeation film 10, and as will be described later, depending on the concentration difference (gradient) of lithium ions between the stock solution 5 and the recovery solution 6 (both electrodes). Lithium ions (not shown) contained in the stock solution 5 are selectively permeated (moved) to the recovery solution 6 via the lithium ion selective transmission film 10 (without applying a voltage between them). Can be done. At this time, in addition to the recovery of lithium ions, the current flowing between the electrodes due to the permeation (movement) of lithium ions can be taken out as electric power. That is, it can be used as a battery without applying a voltage to the positive electrode 3 and the negative electrode 4 of the lithium ion recovery device 1A.
On the other hand, the lithium ion recovery device 1A of the present invention can further improve the lithium ion recovery efficiency by performing electrodialysis by applying a voltage between both electrodes.
As described above, the lithium ion selective transmission film of the present invention is used in the lithium ion recovery device, and the lithium ion recovery device provided with the lithium ion selective transmission film of the present invention has an excellent recovery rate of lithium ions. It can be recovered with excellent selectivity.

The lithium ion recovery device of the present invention is not limited to the lithium ion recovery device 1A. For example, in the lithium ion recovery device 1A, the treatment tank 2 has a substantially U-shape, but in the present invention, the shape of the treatment tank 2 can be applied without any particular limitation to the shape usually adopted. Further, the lithium ion recovery device 1A is provided with a magnetic stirrer as a stirring device, but in the present invention, the stirring device may not be provided, and a known stirring device other than the magnetic stirrer (for example, a mechanical stirrer, etc.) may be provided. A shaker) may be provided with a circulation mechanism shown in FIG. 2, which will be described later. The size, structure, material, and the like of the treatment tank 2, the positive electrode 3, and the negative electrode 4 in the lithium ion recovery device 1A are not particularly limited, and a commonly used configuration can be appropriately selected.

<Lithium-containing compound recovery device>
The lithium-containing compound recovery device of the present invention includes the lithium ion recovery device of the present invention, and further includes a device for neutralizing the recovered lithium ions and converting them into a lithium-containing compound. Hereinafter, the lithium ion recovery method 100 of the present invention will be described together with the lithium ion recovery device 100 shown in FIG. 2 as an example.

The lithium-containing compound recovery device 100 shown in FIG. 2 includes a lithium ion recovery device 1B having the lithium ion selective transmission film 10 of the present invention. The lithium ion recovery device 1B has a tubular treatment tank 2, a lithium ion selective transmission film 10 arranged in the treatment tank 2 and defining two isolated spaces in the treatment tank 2, and a lithium ion selective transmission film. It includes a positive electrode 3 arranged in contact with one surface of the 10 and a negative electrode 4 arranged in contact with the other surface of the lithium ion selective transmission film 10. The positive electrode 3 and the negative electrode 4 are connected to the + terminal or the − terminal of the power supply, respectively. The lithium ion selective permeation membrane 10 is provided with a circulation mechanism for circulating the undiluted solution or the recovered solution as a stirring device. This circulation mechanism can also perform the function of exchanging or recovering the undiluted solution or the recovered liquid in addition to the function of stirring them. Specifically, the undiluted solution 5 is transferred from the undiluted solution storage tank 11 to the isolated space by connecting the undiluted solution storage tank 11 that stores (stores) the undiluted solution 5 and the isolated space in which the undiluted solution storage tank 11 and the positive electrode 3 are arranged. Pipe (stock solution transfer pipe) 13a and a pipe (stock solution discharge pipe) 13b that connects the stock solution storage tank 11 and the isolated space in which the positive electrode 3 is arranged and discharges the stock solution 5 from the isolated space to the stock solution storage tank 11. , The pumps 14a and 14b provided in the stock solution transfer pipe 13a and the stock solution discharge pipe 13b, respectively. On the other hand, the recovery liquid 6 is transferred from the recovery storage tank 12 to the isolated space by connecting the recovery storage tank 12 that stores (stores) the recovery liquid 6 and the isolated space in which the recovery storage tank 12 and the negative electrode 4 are arranged. A pipe (recovery liquid discharge) that connects a pipe (recovery liquid transfer pipe) 13c, a recovery liquid storage tank 12 and an isolated space in which the negative electrode 4 is arranged, and discharges the recovery liquid 6 from the isolated space to the recovery liquid storage tank 12. The pipe) 13d and the pumps 14c and 14d provided in the recovery liquid transfer pipe 13c and the recovery liquid discharge pipe 13d, respectively, are provided. Further, the recovery liquid storage tank 12 is provided with a lithium-containing compound recovery unit (tank) 15. The lithium-containing compound recovery unit 15 has a reaction tank that stores the recovery liquid 6 and converts lithium ions into a lithium-containing compound, and further inputs a compound that converts lithium ions into a lithium-containing compound, such as a hopper. It has a part (not shown). This reaction tank is provided with a pipe (recovery liquid transfer pipe) 13e extending to the recovery storage tank 12 and a pump 14e in the middle of the pipe 13e.

The method of recovering a lithium-containing compound by the lithium-containing compound recovery device 100 contains lithium ions recovered by using a normal lithium ion separation film, except that lithium ions are recovered by using the lithium ion selective transmission film 10. It can be done in the same way as the method of converting to a compound. Specifically, the undiluted solution 5 is stored in the undiluted solution storage tank 11. The undiluted solution 5 is sent by the pump 14a through the pipe 13a to the isolated space of the processing tank 2 where the positive electrode 3 is arranged, and is returned to the undiluted solution storage tank 11 through the pipe 13b by the pump 14b. In this way, the undiluted solution 5 circulates between the undiluted solution storage tank 11 and the processing tank 2. On the other hand, the recovery liquid 6 (dilute hydrochloric acid or the like) is stored in the recovery liquid storage tank 12. The recovered liquid 6 is sent by the pump 14c through the pipe 13c to the isolated space of the processing tank 2 where the negative electrode 4 is arranged, and is returned to the recovered liquid storage tank 12 through the pipe 13d by the pump 14d. In this way, the recovery liquid 6 circulates between the recovery liquid storage tank 12 and the treatment tank 2. In the lithium-containing compound recovery device 100, lithium ions (not shown) are recovered in the recovery liquid 6 by the lithium ion recovery device 1B while circulating the stock solution 5 and the recovery liquid 6 as necessary. The method of recovering lithium ions using the lithium ion recovery device 1B is the same as the method of recovering lithium ions using the lithium ion recovery device 1A.

After the lithium ions are recovered and the concentration of lithium ions in the recovery liquid 6 in the recovery liquid storage tank 12 reaches a desired value, the recovery liquid 6 passes through the pipe 13e by the pump 14e and the lithium-containing compound recovery unit. Sent to 15. In the lithium-containing compound recovery unit 15, a compound that converts lithium ions into a lithium-containing compound, for example, an _{aqueous solution of sodium carbonate (Na 2} CO ₃ ) is added to the recovery liquid 6 to obtain a lithium-containing compound (Li ₂ CO ₃ ). A precipitate can be obtained. This precipitate can be solid-liquid separated by a conventional method, purified if necessary, and dried to obtain a powder of _{a lithium-containing compound, for example, Li 2} CO _3.
As described above, the lithium-containing compound recovery device 100 provided with the lithium ion recovery device 1B can recover the lithium-containing compound having high lithium ion purity with high productivity.

The lithium-containing compound recovery device of the present invention is not limited to the lithium-containing compound recovery device 100. For example, the lithium ion recovery device included in the lithium-containing compound recovery device can be applied to the lithium ion recovery device 1A and the above modification in addition to the lithium ion recovery device 1B.

Regarding the lithium ion recovery device, the lithium-containing compound recovery device, and the method for recovering lithium ions, for example, Japanese Patent Application Laid-Open No. 2015-34315 and Japanese Patent No. 5765850 can be referred to, if necessary.

Hereinafter, the present invention will be described in more detail based on examples. It should be noted that the present invention is not limited thereto. Further, "room temperature" means 25 ° C. In the chemical structural formulas described below, * indicates a binding site as a structural unit of the polymer.

[Example 1]
(1) Synthesis of polymer (B) [Synthesis Example 1-1] Synthesis of polymer (P1-1) A polymer (P1-1) was synthesized according to the following scheme.

By exchanging ions of 3-mercapto-1-sodium propanesulfonate (manufactured by Tokyo Chemical Industry Co., Ltd.) with Amberlite (registered trademark, ion exchange resin, manufactured by Aldrich) in which Li was previously substituted with an aqueous solution of lithium acetate, 3 -Lithium mercapto-1-propanesulfonate was obtained.
To a 50 ml flask, 2.4 g of lithium 3-mercapto-1-propanesulfonate and 6.4 g of dimethylacetamide (DMAc) were added, and the mixture was stirred at 60 ° C. for 30 minutes. After that, further, NISSO-PB B-1000 (trade name, 1,2-polybutadiene homopolymer, manufactured by Nippon Soda) 1.0 g, V-601 (trade name, oil-soluble azo polymerization initiator, Wako Pure Chemical Industries, Ltd.) (C) 1.4 g and DMAc 3.2 g were added, and the mixture was stirred at 60 ° C. for 30 minutes under a nitrogen atmosphere, and further stirred at 80 ° C. for 8 hours. After returning the temperature of the reaction solution to room temperature, this reaction solution is added to 135 g of isopropyl alcohol (IPA), and the precipitate is washed with 135 g of IPA to obtain 1.7 g of the polymer (P1-1). (Mn3700, ratio of structural units represented by the general formula (B1) in the polymer: 70 mol%).

[Synthesis Example 1-2] Synthesis of Polymer (P1-2) In the synthesis of the above polymer (P1-1), the same procedure was used except that lithium 3-mercapto-1-propanesulfonate was changed to the corresponding compound. The following polymer (P1-2) was synthesized (Mn2900, the ratio of structural units represented by the general formula (B1) in the polymer: 70 mol%).

[Synthesis Example 1-3] Synthesis of Polymer (P1-3) In the synthesis of the above polymer (P1-1), NISSO-PB B-1000 was used as NISSO-PB JP-100 (trade name, epoxidized polybutadiene, Nippon Soda Corporation). The following polymer (P1-3) was synthesized in the same manner except that the polymer (manufactured by) was changed to (Mn4300, ratio of structural units represented by the general formula (B1) in the polymer: 70 mol%).

[Synthesis Example 1-4] Synthesis of Polymer (P1-4) In the synthesis of the above polymer (P1-1), the same applies except that the amount of lithium 3-mercapto-1-propanesulfonate used was changed to 0.8 g. The polymer (P1-4) was synthesized (Mn3000, the ratio of the structural unit represented by the general formula (B1) in the polymer: 50 mol%).

[Synthesis Example 2-1] Synthesis of Polymer (P1-5) A polymer (P1-5) was synthesized according to the following scheme.

To a 100 ml flask, 0.8 g of lithium hydroxide monohydrate (manufactured by Wako Pure Chemical Industries, Ltd.), 15 g of water, 15 g of IPA, and 2.5 g of 3-aminopropanesulfonic acid (manufactured by Aldrich) were added, and 78 The temperature was raised while stirring to ° C. Further, 5.0 g of NISSO-PB JP-100 (trade name, epoxidized polybutadiene, manufactured by Nippon Soda Co., Ltd.) was slowly added, and the mixture was reacted at the same temperature for 20 hours. By concentrating the obtained reaction solution, 7.6 g of the polymer (P1-5) could be obtained (Mn2200, ratio of structural units represented by the general formula (B1) in the polymer: 20 mol%).

[Synthesis Example 2-2] Synthesis of Polymer (P1-6) In the synthesis of the above polymer (P1-5), the following polymer (P1) was prepared in the same manner except that 3-aminopropanesulfonic acid was changed to the corresponding compound. -6) was synthesized (Mn2000, the ratio of the structural unit represented by the general formula (B1) in the polymer: 20 mol%).

(2) Preparation of Lithium Ion Selective Permeation Film 0.12 g of the above polymer (P1-1) was dissolved in 0.8 g of dimethyl sulfoxide (DMSO), and poly (acrylonitrile-co-butadiene) (P1 in Table 1 below). After adding 2.6 g of an 11 mass% tetrahydrofuran (THF) solution of Tg-20 ° C. (manufactured by Aldrich), the mixture was mixed at room temperature for 30 minutes. To this mixed solution, _{0.4 g of Li 1.5} Al _0.5 Ge _1.5 P ₃ O ₁₂ (median diameter 10 μm, manufactured by Wako Pure Chemical Industries, Ltd.) was added, mixed at room temperature for 1 hour, and the suspension was prepared. It was adjusted. This suspension was applied onto a petri dish having a diameter of 4.9 cm, allowed to stand overnight at room temperature, and then air-dried at 50 ° C. for 5 hours and vacuum-dried at 100 ° C. for 5 hours. A 101 lithium ion selective permeable membrane (thickness 200 μm) was prepared.
Further, the constituent materials of the lithium ion selective transmission film (lithium ion conductor (A), polymer (B), polymer (C), organic solvent) were used in Test No. Except for the fact that the composition shown in Table 1 below was adopted instead of the composition of 101, Test No. Similar to the preparation of the lithium ion selective transmission membrane of 101, the test No. Lithium ion selective permeation membranes of 102 to 108 and c11 to c14 were prepared. The thickness was 200 μm in each case. In addition, the test No. The lithium ion selective permeation films of c11, c12 and c14 had insufficient binding properties and could not be taken out as a film, as shown in the evaluation of film forming property described later. In addition, the test No. Although the lithium ion selective transmission film of c13 could be formed into a film, it had many defects and the following lithium ion selective transmission film could not be evaluated.
Test No. 101-108 are the lithium ion selective permeation membranes of the present invention, and Test No. c11 to c14 are lithium ion selective permeable membranes for comparison.

(3) Evaluation of Lithium Ion Selective Permeation Film Each of the above-mentioned lithium ion selective permeation films was evaluated for film formation property, film strength, lithium ion recovery rate and selectivity, and water permeability. The results are summarized in Table 1 below.

[Film film property]
The prepared film was evaluated for film forming property by applying the following evaluation criteria. Defects such as cracks in the membrane were observed on the membrane surface.
-Evaluation criteria-
A: The film had no defects such as cracks and could be taken out as a film from a petri dish.
B: There was one defect such as a crack in the film, but it could be taken out as a film from the petri dish.
C: There were two or more defects such as cracks in the film, but it could be taken out as a film from the petri dish.
D: The particles were not sufficiently bound to each other and could not be taken out as a film from the petri dish.

[Membrane strength test: reference test]
For the prepared film, a test piece having a length of 3 cm, a width of 3 cm, and a thickness of 200 μm was prepared. The 90 ° bending test was repeated for this test piece. After bending at an angle of 90 °, the operation of returning to the original state (angle 0 °) was counted as one time, the number of times until the test piece broke was calculated, and the film strength was evaluated by applying the following evaluation criteria. The breakage of the test piece means a state in which a defect such as a crack has occurred.
-Evaluation criteria-
A: 21 times or more B: 11 to 20 times C: 6 to 10 times D: 5 times or less

[Electrodialysis test]
The prepared membrane was cut into a size of 1.7 cm in diameter and 200 μm in thickness, and a lithium ion selective permeable membrane was prepared. In the apparatus (manufactured by TechnoSigma) provided with the positive electrode 3 and the negative electrode 4 shown in FIG. 1, the prepared lithium ion selective permeable film 10 is arranged, and the stock solution 5 containing LiOH and NaOH at concentrations of 0.1 M each on the anode side. 10 ml of (solvent: water) was poured. Next, 10 ml of water (recovery liquid 6) was poured on the cathode side, and electrodialysis was performed at a voltage of 3 V and 25 ° C. for 3 hours.

(Lithium ion recovery rate)
By measuring the lithium ion concentration of the recovered liquid 6 after electrodialysis for 3 hours, the proportion of lithium ions transferred from the stock solution 5 to the recovered liquid 6 was obtained, and the lithium ion recovery rate was evaluated by applying the following evaluation criteria. ..
-Evaluation criteria-
A: 10% or more B: 5% or more and less than 10% C: Above the detection limit and less than 5% D: Below the detection limit

(Lithium ion selectivity)
Ratio of lithium ions to the total amount of lithium ions and sodium ions in the recovered liquid 6 after electrodialysis for 3 hours (Li ⁺ content (mol) / [Li ⁺ and Na ⁺ total content (mol)]] ) Was obtained, and the lithium ion selectivity was evaluated by applying it to the following evaluation criteria.
-Evaluation criteria-
A: 0.7 or more B: 0.5 or more and less than 0.7 C: 0.3 or more and less than 0.5 D: less than 0.3

(Permeability: Reference test)
_{Obtain the} rate of increase in the weight of water in the recovered liquid 6 (([W 3h − W ₀ ] / W ₀ ) × 100%) before and after electrodialysis for 3 hours, and apply it to the following evaluation criteria to evaluate the permeability. did. W ₀ is the weight (g) of water in the recovery liquid 6 before electrodialysis for 3 hours, and W _3h is the weight (g) of water in the recovery liquid 6 after electrodialysis for 3 hours. Each is shown.
-Evaluation criteria-
A: Less than 0.3% B: 0.3% or more and less than 0.6% C: 0.6% or more and less than 1.0% D: 1.0% or more

<Note in Table 1>
(1) Lithium ion conductor (A)
LAGP: Li _1.5 Al _0.5 Ge _1.5 P ₃ O ₁₂ (Median diameter 10 μm, manufactured by Wako Pure Chemical Industries, Ltd.)
(2) Polymer (B)
(P1-1) to (P1-6): Polymers (P1-1) to (P1-6) synthesized above.
(CP1-1): Poly (ethylene-co-acrylic acid) (manufactured by Aldrich)
(CP1-2): A polymer (cP1-1) neutralized with NaOH (neutralization rate of 90% or more) at the time of liquid preparation.
SP value: Indicates the SP value of the structural unit represented by the general formula (B1). However, for the polymers (cP1-1) and (cP1-2), the SP value of the structural unit of the acrylic acid component is shown.
(3) Polymer (C)
(P1): Poly (acrylonitrile-co-butadiene) (Tg-20 ° C., acrylonitrile content 37-39% by mass, manufactured by Aldrich)
(P2): Polyacrylonitrile (Tg ≧ 50 ° C., manufactured by Aldrich)
(P3): Epoxidized natural rubber (Tg-15 ° C, epoxidation rate 50%, obtained from Sanyo Trading Co., Ltd.)
"-" In the table indicates that the component is not contained.

As is clear from Table 1 above, No. For c11, a small molecule organolithium salt compound and a water-insoluble polymer (C) were used, and No. For c12, an anionic group-containing polymer in which a carboxy group was directly bonded to the polymer main chain was used, and No. Reference numeral 14 is used to prepare a lithium ion selective permeation membrane using the Na salt of this anionic group-containing polymer, and all of them have a polymer (B) having a structural unit represented by the general formula (B1) in the present invention. ) Is not contained. These No. None of c11, c12 and c14 could be removed as a film from the petri dish. In addition, No. For c13, a lithium ion selective permeation film is produced using an anionic group-containing polymer in which a carboxy group is directly bonded to the polymer main chain and a water-insoluble polymer (C), and the general formula (B1) in the present invention is used. It does not contain the polymer (B) having the structural unit represented. This No. Although c13 could be taken out as a membrane from a petri dish, the obtained membrane had many defects, and its performance as a lithium ion selective permeation membrane could not be evaluated.
On the other hand, the lithium ion selective permeable film of the present invention having the polymer (B) having the structural unit represented by the general formula (B1) was excellent in film forming property. Moreover, this lithium ion selective permeation membrane showed excellent lithium ion recovery rate and lithium ion selectivity. Further, the lithium ion selective permeable membrane of the present invention was excellent in both membrane strength and water permeability.

1A, 1B Lithium ion recovery device 2 Treatment tank 3 Positive electrode 4 Negative electrode 5 Undiluted solution 6 Recovery liquid 10 Lithium ion selective permeation film 11 Undiluted solution storage tank 12 Recovery liquid storage tank 13a to e Piping 14a to e Pump 15 Lithium-containing compound recovery unit 16 Power supply 17 Stirrer 18 Turntable 100 Lithium-containing compound recovery device

Claims (8)

A lithium ion selective permeable membrane containing a lithium ion conductor (A) and a polymer (B) having a structural unit represented by the following general formula (B1).

In the above formula, L ¹ and L ² each independently represent an alkylene group which may have a substituent, R ^{1 to} R ³ each independently represent a hydrogen atom or an alkyl group, and A is −NR ⁴ −. , -O- or -S-, R ⁴ represents a hydrogen atom or an alkyl group, and Y ^B1 represents an anionic group having a lithium ion as a counter ion. * Indicates the binding site as a structural unit of the polymer. The lithium ion selective permeable membrane according to claim 1, wherein the SP value of the structural unit represented by the general formula (B1) is 14 or more and 24 or less. The lithium ion selective permeable membrane according to claim 1 or 2, wherein the structural unit represented by the general formula (B1) is a structural unit represented by the following general formula (B2).

In the above formula, L ²¹ and L ²² each independently represent an alkylene group having 1 to 7 carbon atoms, R ^{21 to} R ²³ each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and Y ^B2 is It has the same meaning as Y ^B1 . * Indicates the binding site as a structural unit of the polymer. The lithium ion selective permeation membrane according to any one of claims 1 to 3, wherein the anionic group is −SO ₃ ⁻ Li ^+. A water-insoluble polymer (C) different from the polymer (B), which is one or more of a cyano group, an amide group, an amino group, a hydroxy group, a sulfanyl group, an ether bond, a sulfide bond and a urethane bond. The lithium ion selective permeable film according to any one of claims 1 to 4, which comprises a water-insoluble polymer (C) having a glass transition temperature of 0 ° C. or lower. A lithium ion recovery device having the lithium ion selective permeation membrane according to any one of claims 1 to 5. A lithium-containing compound recovery device comprising the lithium ion recovery device according to claim 6. A method for recovering lithium ions, which comprises recovering lithium ions using the lithium ion selective permeation membrane according to any one of claims 1 to 5.

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