Lithium separation member, lithium separation device, and method for manufacturing lithium separation member

Abstract

A lithium separation member 10 comprises: a lithium-ion conductor layer 11 that selectively transmits lithium ions; a support base material 13 that contains yttria-stabilized zirconia and supports the lithium-ion conductor layer 11; and an adhesive layer 12 that bonds the lithium-ion conductor layer 11 and the support base material 13, and contains lithium zirconate This makes it possible to provide, inter alia, a lithium separation member comprising an electrolyte membrane, wherein cracks are unlikely to occur in the electrolyte membrane even when the electrolyte membrane is reduced in thickness or increased in area.

Description

Lithium separation member, lithium separation apparatus, and method for producing lithium separation member

[0001] The present invention relates to a lithium separation member, a lithium separation apparatus, and a method for producing a lithium separation member. In particular, the present invention relates to a lithium separation member having a function of selectively permeating lithium ions.

[0002] In recent years, demand for lithium for applications such as lithium ion storage batteries has been expanding. Therefore, there is a need for processes that achieve both improved efficiency and environmental advantages when refining lithium, as well as resource circulation and recycling of lithium. As methods for refining lithium and recovering lithium resources, a technique for recovering lithium by electrodialysis using an electrolyte membrane has been proposed.

[0003] Patent Document 1 discloses a lithium conductive sheet. This lithium conductive sheet has a composition of Li ３Ｘ La ２／３－Ｘ TiO ３ (wherein X is 0.05 or more and 0.3 or less), the area of the main surface is 20 cm ２ or more, the thickness is 10 µm or more and 1000 µm or less, the distortion rate when viewed from the direction in which the main surface extends is 10 or less, the average value of measurement results of lithium ion conductivity at 50 randomly selected locations is 3.0×10 －４ S / cm or more, and the standard deviation of the measurement results is 1.0×10 －４ S / cm or less.

[0004] Patent Document 2 discloses a metal ion recovery apparatus. In this metal ion recovery apparatus, a selectively permeable membrane that selectively permeates Li is used, and a mesh-shaped positive electrode and a mesh-shaped negative electrode are respectively formed on both main surfaces of the flat selectively permeable membrane. This structure is provided in a treatment tank, and a stock solution containing Li ions and a recovery liquid into which Li is recovered are partitioned by the selectively permeable membrane in the treatment tank. As the selectively permeable membrane, lithium nitride (Li ３ N), which is a super lithium ion conductor, Li １０ GeP ２ S １２ , (La ｘ , Li ｙ )TiOｚ Li １＋ｘ＋ｙ Al ｘ (Ti, Ge) ２－ｘ Si ｙ P ３－ｙ O １２ The following can be used.

[0005] Japanese Patent Publication No. 2023-54889 Japanese Patent Publication No. 2015-34315

[0006] To increase the amount of lithium recovered, reducing the resistance and increasing the area of ​​the electrolyte membrane are effective. However, existing ceramic solid electrolyte membranes are prone to cracking, limiting their thinning and increasing their area, and thus failing to achieve sufficient lithium processing capacity. On the other hand, supporting the electrolyte membrane with a support substrate is conceivable, but this has resulted in problems with delamination due to insufficient adhesion between the electrolyte membrane and the support substrate. The present invention aims to provide a lithium separation member, etc., that can improve the adhesion between the electrolyte membrane and the support substrate and is less prone to delamination.

[0007] To solve the above problem, the present invention provides a lithium separation member comprising: a lithium ion conductor layer that selectively permeates lithium ions; a support base material that contains yttria-stabilized zirconia and supports the lithium ion conductor layer; and an adhesive layer that bonds the lithium ion conductor layer and the support base material and contains lithium zirconate. Furthermore, the present invention provides a lithium separation device comprising: a lithium separation member that is a member for selectively permeating lithium ions; and a pair of electrodes disposed on respective sides of two main surfaces of the lithium separation member, wherein the lithium separation member includes: a lithium ion conductor layer that selectively permeates lithium ions; a support base material that contains yttria-stabilized zirconia and supports the lithium ion conductor layer; and an adhesive layer that bonds the lithium ion conductor layer and the support base material and contains lithium zirconate. Furthermore, the present invention provides a method for producing a lithium separation member, comprising: a first sheet production step of producing a first sheet that contains a lithium ion conductor that selectively permeates lithium ions and serves as a base for a dense lithium ion conductor layer having a dense structure; a second sheet production step of producing a second sheet that contains yttria-stabilized zirconia and serves as a base for a support base material that supports the dense lithium ion conductor layer; a third sheet production step of producing a third sheet that serves as a base for an adhesive layer that bonds the dense lithium ion conductor layer and the support base material and contains lithium zirconate; and a firing step of firing the first sheet, the second sheet and the third sheet to obtain the dense lithium ion conductor layer, the support base material and the adhesive layer.

[0008] An object of the present invention is to provide a lithium separation member or the like that can improve the adhesion between an electrolyte membrane and a support base material and is less prone to peeling.

[0009] FIG. 1 is a diagram illustrating a lithium separation apparatus to which the present embodiment is applied. FIG. 1 is a diagram illustrating a first example of the lithium separation member according to the first embodiment. FIG. 2 is a diagram illustrating a case where the lithium separation member having the structure shown in FIG. 2 is formed into a cylindrical shape. FIG. 3 is a diagram illustrating a second example of the lithium separation member according to the first embodiment. FIG. 4 is a diagram illustrating a case where the lithium separation member shown in FIG. 4 has a front-back symmetrical structure. (a) to (b) are diagrams illustrating the lithium separation member according to the second embodiment. (a) to (c) are views of the lithium separation member of FIG. 6(a) viewed from the direction VII, and are diagrams illustrating the shape of the opening of the through-hole. FIG. 7 is a diagram illustrating a case where the lithium separation member of FIG. 6(b) has a front-back symmetrical structure. FIG. 8 is a diagram illustrating an example of a method for manufacturing the lithium separation member according to the first embodiment. FIG. 9 is a diagram illustrating an example of a method for manufacturing the lithium separation member according to the second embodiment. FIG. 10 is a diagram illustrating another example of the method for manufacturing the lithium separation member according to the second embodiment.

[0010] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0011] <Description of Lithium Separation Apparatus 1> FIG. 1 is a diagram illustrating a lithium separation apparatus 1 to which the present embodiment is applied. The illustrated lithium separation apparatus 1 separates lithium ions (Li ＋ ) from a lithium-containing solution and recovers the lithium ions. The lithium separation apparatus 1 includes a lithium separation member 10, electrodes 20 and 30, and a solution tank 40. The lithium separation member 10 is a member capable of selectively permeating lithium ions. The electrode 20 serves as a positive electrode, and the electrode 30 serves as a negative electrode. The solution tank 40 stores a lithium-containing solution and a recovery solution.

[0012] In this case, electrodes 20 and 30 are placed on each of the two main surfaces of the lithium separation member 10. Here, "main surface" refers to a surface with a much larger area compared to the other surfaces. In this case, electrodes 20 and 30 are plate-like with a layered structure, as will be described in detail later, and the side surfaces occupy only a small area compared to the total surface area of ​​electrodes 20 and 30. Therefore, in this case, the main surfaces are the two surfaces of electrodes 20 and 30 other than the side surfaces and the back surface. A lithium-containing solution is then placed on the side of electrode 20, which will be the positive electrode. The lithium-containing solution is created by refining lithium resources. Lithium resources include, for example, seawater, roasted and leached liquid from discarded lithium-ion batteries (waste LIBs (Lithium Ion Batteries)), salt lake brine, and geothermal brine. On the side of electrode 30, which will be the negative electrode, a recovery solution such as pure water or an aqueous lithium hydroxide solution is placed. When a DC voltage is applied between electrodes 20 and 30, lithium ions move from the positive electrode 20 through the lithium separation member 10 to the negative electrode 30. On the other hand, it is difficult for other ions to pass through the lithium separation member 10. In other words, the lithium separation member 10 can selectively allow lithium ions to pass through and separate them from other ions.

[0013] Then, carbon dioxide (CO2) is added to the recovered solution. ２ When you blow in lithium ions, lithium carbonate (Li ２ CO ３ It can be precipitated and recovered as lithium carbonate. Lithium carbonate is reused as a battery material.

[0014] <Explanation of the configuration of the lithium separation member 10> Next, the lithium separation member 10 will be described according to the first and second embodiments.

[0015] [First Embodiment] Figure 2 shows a first example of the lithium separation member 10 of the first embodiment. The lithium separation member 10 shown consists of a lithium ion conductor layer 11, an adhesive layer 12, and a support substrate 13. The lithium ion conductor layer 11 is an example of an electrolyte membrane and is a functional layer that selectively permeates lithium ions. The lithium ion conductor layer 11 contains a lithium ion conductor. The lithium ion conductor is, for example, a perovskite oxide, and more specifically, La ２／３-ｘ Li ３ｘ TiO ３ This is a lithium ion conductive solid electrolyte ceramic lithium lanthanum titanate (LLTO) represented by . In this case, the lithium ion conductor is, for example, La ０．５７ Li ０．２９ TiO ３ It can be made into this composition.

[0016] However, this is not limited to the above, and a solid electrolyte material exhibiting lithium ion conductivity can be used for the lithium ion conductor layer 11. For example, Li １．５ Al ０．５ Ge １．５ (PO ４ ) ３ Polyanionic solid electrolytes having a Li-substituted NASICON-type structure, such as (LAGP), lithium lanthanum niobate: Li ５ La ３ Nb ２ O １２ Lithium lanthanum tantalate: Li ５ La ３ Ta ２ O １２ Lithium zirconate lanthanum: Li ７ La ３ Zr ２ O １２ (LLZO) and garnet-type solid electrolytes based on LLZO with various elements substituted, Li １＋ｘ Al ｘ Ti ２－ｘ (PO ４ ) ３ Lithium aluminum titanium phosphate (LATP), Li ２O-Al ２ O ３ -SiO ２ -P ２ O ５ -TiO ２ - Lithium ion conductive glass ceramic (LICGC), represented by GeO, Li ２，９ PO ３．３ N ０．４６ Lithium oxynitride phosphate (LASiPTTiGeO), LLTO nitride (LLTON), LLZO nitride (LLZON), LASiPTTiGeO nitride (LASiPTTiGeON), etc. may also be used.

[0017] The lithium-ion conductor layer 11 is a dense lithium-ion conductor layer with a dense structure. In other words, the lithium-ion conductor layer 11 has a low porosity, less than 10%. The dense structure enhances the selectivity of lithium ions. Furthermore, the thickness of the lithium-ion conductor layer 11 is preferably between 5 μm and 1000 μm. If the thickness of the lithium-ion conductor layer 11 is less than 5 μm, pores connecting the front and back surfaces are easily formed, making it difficult to selectively allow lithium ions to pass through. Also, if the thickness of the lithium-ion conductor layer 11 exceeds 1000 μm, the resistance increases, and the lithium separation performance tends to deteriorate. In addition, flexibility decreases, and the entire lithium separation member 10 becomes more prone to breakage when bent.

[0018] In this case, the lithium-ion conductor dense layer is the same as the lithium-ion conductor dense layer 111 described later, and it can also be said that the lithium-ion conductor layer 11 in Figure 2 is the lithium-ion conductor dense layer 111. Therefore, hereafter, the lithium-ion conductor layer 11 of the lithium separation member 10 in Figure 2 may be referred to as the lithium-ion conductor dense layer 111.

[0019] The support substrate 13 is a support that supports the lithium ion conductor layer 11. The support substrate 13 is zirconia, for example, yttria-stabilized zirconia (YSZ). In this case, zirconia (ZrO ２ ) is used as a stabilizer (yttria: Y ２ O ３A mixture containing ) in an amount of 1.5 mol% to 10 mol% can be used. The amount of yttrium oxide added is preferably 2.5 mol% to 8 mol%, and more preferably 3.0 mol% to 5.5 mol%. Within the above range, the strength of the support substrate 13 can be further increased and damage to the lithium separation member 10 can be further suppressed.

[0020] Furthermore, the support substrate 13 has a porous structure. That is, the support substrate 13 has high porosity, with a porosity of 20% to 60%. The porosity is determined by polishing the cross section of the support substrate with a CP (cross-section polisher) and then obtaining an image magnified 1,000 to 20,000 times using an FE-SEM (field emission scanning electron microscope). Next, the cross section image is analyzed using the image analysis software HALCON manufactured by MVTec Corporation to highlight the porosity. Next, the total area of ​​the solid portion and the total area of ​​the porosity portion composed of the support substrate 13 are determined from the analyzed cross section image. Next, the area occupancy rate of the porosity portion is calculated. This area occupancy rate of the porosity portion is calculated for five fields of view of the FE-SEM, and the arithmetic mean of these is taken as the porosity of the support substrate 13. Furthermore, the average pore diameter is preferably 0.1 μm to 50 μm. The average pore diameter is obtained by calculating the average equivalent circle diameter for each of the five cross-sectional images after the analysis described above, and then taking the arithmetic mean of the average equivalent circle diameters for each of the five cross-sectional images. The equivalent circle diameter is the diameter of a circle having the same area as the cross-sectional area of ​​the pores. By making the support substrate 13 porous, lithium can be separated when the raw solution or recovered solution permeates the support substrate 13 and comes into contact with the lithium ion conductor layer 11. The thickness of the support substrate 13 is preferably 0.5 mm or more and 10 mm or less. If the thickness of the support substrate 13 is less than 0.5 mm, the strength of the lithium separation member 10 tends to be insufficient. Also, if the thickness of the support substrate 13 exceeds 10 mm, the resistance increases and the lithium separation performance tends to decrease.

[0021] By providing the support substrate 13, the strength of the lithium separation member 10 is improved, and cracks in the lithium ion conductor layer 11 can be suppressed. Furthermore, since the strength can be ensured by the support substrate 13, it becomes easier to increase the area of ​​the lithium separation member 10. In addition, since the lithium ion conductor layer 11 can be formed as a thin film, it becomes possible to reduce resistance and improve the lithium recovery rate and amount.

[0022] The adhesive layer 12 is a functional layer that adheres the lithium ion conductor layer 11 and the support substrate 13, thereby improving the adhesion between the lithium ion conductor layer 11 and the support substrate 13. The adhesive layer 12, like the support substrate 13, is made of zirconia (ZrO ２ A mixture containing yttrium oxide in an amount of 1.5 mol% to 10 mol% can be used as a stabilizer. The adhesive layer 12 is made of lithium zirconate (Li ２ ZrO ３ This includes ), which improves the adhesion between the lithium-ion conductor layer 11 and the support substrate 13, making delamination less likely.

[0023] The presence of lithium zirconate in the adhesive layer 12 can be confirmed by analyzing the adhesive layer 12 using an X-ray diffractometer (XRD). Specifically, the lithium ion conductor layer 11 of the lithium separation member 10 is polished and removed to expose the adhesive layer 12. Next, the exposed surface is analyzed using XRD to obtain an X-ray diffraction pattern. By comparing the obtained X-ray diffraction pattern with an ICDD (International Center for Diffraction Data) card, the substances contained in the adhesive layer 12 can be identified. In this embodiment, when the lithium zirconate content is expressed in percentage, this represents the volume fraction of lithium zirconate in the adhesive layer 12. The lithium zirconate content of the adhesive layer 12 can be determined by analyzing the cross-section of the adhesive layer 12 using an SEM (Scanning Electron Microscope) and an EDS (Energy Dispersive X-ray Spectroscopy). In other words, the lithium separation member 10 is cut and polished. Then, using a SEM, the polished cross-section is examined, and SEM images are acquired in three fields of view at an arbitrary magnification (2000 to 10000x) where 10 or more lithium zirconate particles can be identified. The area occupied by lithium zirconate on the acquired images is then calculated by image analysis. More specifically, lithium zirconate is identified on the SEM image, and the area ratio of lithium zirconate is calculated by dividing the area of ​​lithium zirconate in that field of view by the total area of ​​the field of view. This area ratio is then considered to be the volume ratio of lithium zirconate. Lithium zirconate particles can be identified by combining the analysis results of XRD, SEM, and EDS. Specifically, XRD analysis confirms the presence of lithium zirconate and yttria-stabilized zirconia in the adhesive layer 12. Next, the cross-section of the adhesive layer 12 is analyzed by EDS to confirm the distribution of each element. At this time, particles in which yttrium and zirconium coexist can be identified as yttria-stabilized zirconia.On the other hand, particles in which yttrium is not detected, appear darker than yttria-stabilized zirconia particles in SEM backscattered electron images, and in which zirconium is detected can be identified as lithium zirconate.

[0024] The adhesive layer 12 preferably contains 10% to 80% lithium zirconate. If the lithium zirconate content is less than 10%, it is difficult to obtain an improved adhesion effect. Also, if the lithium zirconate content exceeds 80%, the strength of the lithium separation member 10 tends to decrease. The adhesive layer 12 preferably has a thickness of 200 μm or less. If the thickness of the adhesive layer 12 exceeds 200 μm, the improved adhesion effect saturates, and resistance increases, which tends to decrease lithium separation performance. The thickness of the adhesive layer 12 can be calculated by observing the cross-section with an SEM. First, the lithium zirconate particles located at the position furthest from the interface between the lithium ion conductor layer 11 and the adhesive layer 12 in the thickness direction are identified from the cross-sectional SEM image. The line connecting the lithium zirconate particles located furthest from the interface between the lithium ion conductor layer 11 and the adhesive layer 12 is defined as the boundary between the adhesive layer 12 and the support substrate 13, and the distance from the interface between the lithium ion conductor layer 11 and the adhesive layer 12 to the boundary between the adhesive layer 12 and the support substrate 13 is defined as the thickness of the adhesive layer 12.

[0025] Furthermore, the adhesive layer 12 may also include a lithium ion conductor as a component other than lithium zirconate and yttria-stabilized zirconia. In other words, the adhesive layer 12 further includes the components that make up the lithium ion conductor layer 11. Specifically, the component other than lithium zirconate and yttria-stabilized zirconia may be, for example, lithium lanthanum titanate (LLTO). The mixing ratio of the lithium ion conductor and lithium zirconate can be 10% to 90% by volume. The mixing ratio of the lithium ion conductor and yttria-stabilized zirconia is preferably 20% to 80%, and more preferably 30% to 60%. By making the adhesive layer 12 such a component, the adhesive strength between the lithium ion conductor dense layer 11 and the support substrate 13 can be improved and peeling can be further suppressed.

[0026] Furthermore, the adhesive layer 12 has a porous structure similar to that of the support substrate 13. The porosity of the adhesive layer 12 is preferably 20% to 60%. The average pore diameter is preferably 0.1 μm to 50 μm. The porosity and average pore diameter of the adhesive layer 12 are measured in the same manner as described above for the support substrate 13.

[0027] The lithium separation member 10 of this embodiment can be rectangular in shape, for example, with dimensions of 50 mm or more and 300 mm or less. Alternatively, it may be disc-shaped, with dimensions of 50 mm or more and 300 mm or less. Conventionally, the size of the lithium separation member 10 was limited to approximately 50 mm or 50 mm in diameter, but this embodiment allows for a larger surface area than conventional designs. The lithium separation member 10 can also be cylindrical or rectangular. By making it cylindrical, the contact area with the raw liquid and the recovered liquid can be increased compared to using a plate-shaped lithium separation member, thereby improving the lithium recovery efficiency. Furthermore, the cylindrical shape allows for greater strength compared to the plate-shaped case.

[0028] Figure 3 shows a case where the lithium separation member 10 of the structure in Figure 2 is cylindrical. In the illustrated lithium separation member 10, the lithium ion conductor layer 11 is cylindrical on the outside, and the support base material 13 is cylindrical on the inside, so that the overall shape is also cylindrical. The adhesive layer 12 is also cylindrical and is provided between the lithium ion conductor layer 11 and the support base material 13. There is no particular upper limit to the opening diameter (maximum inner diameter) of the cylindrical lithium separation member 10, but for example it is 1000 mm or less, preferably 500 mm or less, and particularly preferably 150 mm or less. By using such a lithium separation member 10, the contact area between the raw liquid or recovered liquid and the lithium separation member 10 is increased, a sufficient amount of liquid can be passed through the cylinder, and the recovery efficiency of lithium contained in the raw liquid can be improved. There is no particular limit to the length of the cylindrical lithium separation member 10, but for example it can be 10 mm or more, and preferably 100 mm or more. If the length of the selective permeable membrane is 10 mm or more, the contact area between the raw solution or recovered solution and the lithium separation member 10 can be increased, thereby improving the recovery efficiency of lithium contained in the raw solution. There is no particular upper limit to the length, but for example, it should be 2000 mm or less, and typically it is 1000 mm or less. The opening diameter and length of the cylindrical lithium separation member 10 should preferably be set to an appropriate combination considering the amount of liquid to be passed through and the contact efficiency between the lithium separation member 10 and the raw solution or recovered solution.

[0029] Figure 4 shows a second example of the lithium separation member 10 of the first embodiment. The lithium separation member 10 shown includes a lithium ion conductor layer 11 consisting of a dense lithium ion conductor layer 111 and a porous lithium ion conductor layer 112. In other words, the lithium ion conductor layer 11 in Figure 4 has a laminated structure in which the dense lithium ion conductor layer 111 and the porous lithium ion conductor layer 112 are laminated together. The dense lithium ion conductor layer 111 is the same as the lithium ion conductor layer 11 in Figure 2 and has a dense structure.

[0030] The lithium-ion conductor porous layer 112 has the same composition as the lithium-ion conductor dense layer 111 and is a functional layer that selectively allows lithium ions to pass through. That is, the lithium-ion conductor porous layer 112 is, for example, a lithium-ion conductive solid electrolyte ceramic (LLTO).

[0031] The lithium-ion conductor porous layer 112 is positioned between the lithium-ion conductor dense layer 111 and the adhesive layer 12, and has a porous structure. Specifically, the lithium-ion conductor porous layer 112 has high porosity, with a porosity of 20% to 60%. Furthermore, the average pore diameter is preferably 0.1 μm to 50 μm. The porosity and average pore diameter of the lithium-ion conductor porous layer 112 are measured in the same manner as the support substrate 13 described above. By making the lithium-ion conductor porous layer 112 porous, the surface area of ​​the lithium-ion conductor layer 11 is increased, resulting in lower resistance. This also makes it possible to improve the lithium recovery rate and amount. The thickness of the lithium-ion conductor porous layer 112 is preferably 5 μm to 500 μm. If the thickness of the lithium-ion conductor porous layer 112 is less than 5 μm, the effect of increasing the surface area is less pronounced. Furthermore, if the thickness of the lithium-ion conductor porous layer 112 exceeds 500 μm, the effect of increased resistance in the thickness direction becomes significant, and the effect of improving lithium separation performance with respect to film thickness decreases. In addition, the lithium-ion conductor porous layer 112 may also be laminated on the upper side of the lithium-ion conductor dense layer 111. By providing the lithium-ion conductor porous layer 112 on both sides of the lithium-ion conductor dense layer 111, it becomes possible to further improve the lithium recovery rate and recovery amount.

[0032] The support substrate 13 is the same as in Figure 2. That is, the support substrate 13 is zirconia, for example, yttria-stabilized zirconia (YSZ). The adhesive layer 12 is also the same as in Figure 2. That is, the adhesive layer 12 contains yttria-stabilized zirconia and lithium zirconate. The components other than yttria-stabilized zirconia and lithium zirconate can be, for example, the components that make up the lithium ion conductor layer 11, for example, lithium lanthanum titanate (LLTO).

[0033] In the case of Figure 4, the adhesion between the lithium-ion conductor layer 11 and the support substrate 13 can be improved, making delamination less likely. The lithium-ion conductor dense layer 111 can also have a symmetrical structure. For example, the lithium-ion conductor porous layer 112 may be present on both sides of the lithium-ion conductor dense layer 111.

[0034] Figure 5 shows the lithium separation member 10 of Figure 4 with a front-to-back symmetrical structure. The lithium separation member 10 shown in the figure is laminated in the following order: support base material 13, adhesive layer 12, lithium ion conductor porous layer 112, lithium ion conductor dense layer 111, lithium ion conductor porous layer 112, adhesive layer 12, and support base material 13. In other words, the lithium ion conductor dense layer 111 is sandwiched between the lithium ion conductor porous layer 112, adhesive layer 12, and support base material 13, which are laminated in the vertical direction in the figure, resulting in a front-to-back symmetrical structure. By adopting a front-to-back symmetrical structure, warping of the lithium separation member 10 can be suppressed and flattened, and damage can also be suppressed. Furthermore, the front-to-back symmetrical structure is not limited to the laminated structure of Figure 5; for example, the lithium separation member 10 shown in Figures 2 and 3 may also have a front-to-back symmetrical structure.

[0035] [Second Embodiment] In the first embodiment, the support base material 13 had a porous structure, but in the second embodiment, the support base material 13 has a dense structure with multiple through holes. Figures 6(a) and 6(b) show the lithium separation member 10 of the second embodiment. Of these, Figure 6(a) shows the case where the support base material 13 of the lithium separation member 10 shown in Figure 2 has the structure of the second embodiment. Similarly, Figure 6(b) shows the case where the support base material 13 of the lithium separation member 10 shown in Figure 4 has the structure of the second embodiment.

[0036] In the second embodiment, the support substrate 13 has a dense structure, so its porosity is low, less than 10%. Furthermore, the support substrate 13 has a plurality of through holes 13h. In this case, the through holes 13h are holes that penetrate from one main surface of the support substrate 13 to the other main surface, and openings 13k are formed on both the one main surface and the other main surface of the support substrate 13. By providing the through holes 13h, lithium can be separated when the raw liquid or recovered liquid enters the through holes 13h and comes into contact with the lithium ion conductor layer 11.

[0037] Figures 7(a) to 7(c) show the lithium separation member 10 of Figures 6(a) to 6(b) as viewed from direction VII, and illustrate the shape of the opening 13k of the through hole 13h. Of these, Figures 7(a) to 7(b) show the case where the shape of the opening 13k is circular. Figure 7(a) shows the case where multiple openings 13k are arranged in a grid pattern, and Figure 7(b) shows the case where multiple openings 13k are arranged in a staggered pattern. Figure 7(c) shows the case where the shape of the opening 13k is rectangular. Note that the shape of the opening 13k is not limited to these. For example, it may be elliptical, triangular, hexagonal, or other polygonal shape, or it may be irregular in shape. Also, the multiple openings 13k do not need to be the same shape, and multiple shapes may be mixed. Furthermore, the arrangement of the through holes 13h is not limited to these. For example, they may be arranged randomly, or the arrangement may be partially changed, such as being different in the center and on the outer periphery. Also, when the shape of the opening 13k is rectangular, the corners may be chamfered. In this case, the chamfer may be an R-chamfer or a C-chamfer. In the case of an R-chamfer, it is preferable that the radius of curvature be 0.5 mm or more.

[0038] The size W1 of the opening 13k of the through hole 13h is preferably 15 mm or less. Furthermore, the size W1 of the opening 13k is preferably such that W1 / thickness of the support base material 13 is 1 or more. Here, the size W1 of the opening 13k is the maximum dimension of the opening 13k. Therefore, in the cases of Figures 7(a) to (b), the size W1 of the opening 13k is the length of the diameter of the circle. Also, in the case of Figure 7(c), the size W1 of the opening 13k is the length of the diagonal of the rectangle. If the size W1 of the opening 13k exceeds 15 mm, the area on which the lithium ion conductor layer 11 stands independently becomes large, resulting in insufficient strength of the lithium ion conductor layer 11 and making it prone to failure. Furthermore, if the thickness W1 / thickness of the support base material 13 is less than 1, the resistance tends to increase due to a decrease in the exposed area of ​​the lithium ion conductor layer 11 and the accumulation of air bubbles within the through hole 13h.

[0039] In this embodiment, the support base material 13 has a frame portion 13s on the outer circumference of the main surface, which is a region where through holes 13h are not formed. The frame portion 13s is the region outside the line drawn so as to be in contact with the outermost through hole 13h, and having a shape similar to the outer shape of the lithium separation member 10. In Figures 7(a) to (c), the outer shape of the lithium separation member 10 is rectangular, and the frame portion 13s is the region outside the rectangle shown by the dotted line in the figure. By providing the frame portion 13s, the strength of the support base material 13 can be improved while maintaining recovery efficiency. The width W2 of the frame portion 13s is preferably 0.5 mm or more. If the width W2 of the frame portion 13s is less than 0.5 mm, the strength of the support base material 13 will decrease, and the lithium separation member 10 will be more prone to damage. Furthermore, the width W2 of the frame portion 13s is preferably 14% or less of the outer dimensions of the support base material 13. If the width W2 of the frame portion 13s exceeds 14% of the outer dimensions of the support base material 13, the effective area having the opening 13k decreases, and the size of the lithium separation device 1 becomes large relative to the lithium processing capacity, resulting in significant space loss. The opening ratio of the through holes 13h in the region where the through holes 13h are formed, excluding the frame portion 13s, is preferably 25% to 95%. The region where the through holes 13h are formed is the region inside the dotted line in the figure. If the opening ratio exceeds 95%, the strength of the support base material 13 decreases, and the lithium separation member 10 becomes more susceptible to damage. Also, if the opening ratio is less than 25%, the exposed area of ​​the lithium ion conductor layer 11 decreases, and the effect of increased resistance due to the reduced exposed area becomes greater than the effect of resistance reduction due to thinning. The width W3 of the crossbar, which is the shortest distance between adjacent through holes 13h in the region where the through holes 13h are formed, excluding the frame portion 13s, is preferably 0.05 mm to 3 mm. If the width W3 of the crossbar exceeds 3 mm, the exposed area of ​​the lithium ion conductor layer 11 decreases, and the effect of increased resistance due to the reduced exposed area becomes greater than the effect of resistance reduction due to thinning. Also, if the width W3 of the crossbar is less than 0.05 mm, the strength of the support base material 13 decreases, and the lithium separation member 10 becomes more susceptible to damage. It is preferable that the width W2 of the frame portion 13s is greater than the width W3 of the crossbar, which is the shortest distance between adjacent through holes 13h in the region where the through holes 13h are formed excluding the frame portion 13s.

[0040] Furthermore, through-holes may also be formed in the adhesive layer 12. In this case, the through-holes 13h of the support substrate 13 are formed to extend into the adhesive layer 12, so as to penetrate both the support substrate 13 and the adhesive layer 12. In this case, the adhesive layer 12 does not have a porous structure and can be a dense layer. In other words, by providing through-holes in the adhesive layer 12, the raw solution or recovered liquid can penetrate these through-holes, so it is not necessary to make it porous.

[0041] The lithium separation member 10 of the second embodiment can also have a front-to-back symmetrical structure. Figure 8 shows the lithium separation member 10 of Figure 6(b) with a front-to-back symmetrical structure. The lithium separation member 10 shown is laminated in the following order: support base material 13, adhesive layer 12, lithium ion conductor porous layer 112, lithium ion conductor dense layer 111, lithium ion conductor porous layer 112, adhesive layer 12, and support base material 13. In other words, the lithium ion conductor dense layer 111 is sandwiched between the lithium ion conductor porous layer 112, adhesive layer 12, and support base material 13, which are laminated in the vertical direction in the figure, resulting in a front-to-back symmetrical structure. Furthermore, through holes 13h are formed in each support base material 13.

[0042] <Explanation of the manufacturing method of the lithium separation member 10> The lithium separation member 10 may be manufactured by any method. For example, it can be manufactured by a combination of extrusion molding, mold casting, press molding, tape molding, printing, etc. Figure 9 is a diagram showing an example of a manufacturing method of the lithium separation member 10 of the first embodiment. Note that Figure 9 illustrates the manufacturing of the lithium separation member 10 having the structure of Figure 2. Here, the lithium separation member 10 is manufactured by producing corresponding green sheets by tape molding, laminating these green sheets, and then pressing and firing them.

[0043] (Preparation of lithium-ion conductor dense layer 111 green sheet) The lithium-ion conductor dense layer 111 green sheet may be manufactured by any method. For example, it can be manufactured as follows. First, a lithium-ion conductor dense layer slurry is prepared by mixing LLTO powder, a dispersant, a solvent, a plasticizer, and a binder. The prepared slurry is then formed into a sheet on a PET film using the doctor blade method to form a green sheet that will become the lithium-ion conductor dense layer 111. At this time, the thickness of the lithium-ion conductor dense layer 111 green sheet can be adjusted by adjusting the coating thickness.

[0044] (Preparation of Lithium Ion Conductor Porous Layer 112 Green Sheet) The lithium ion conductor porous layer 112 green sheet may be manufactured by any method, but for example, it can be manufactured as follows. First, a lithium ion conductor porous layer slurry is prepared by mixing LLTO powder, a dispersant, a solvent, a plasticizer, a binder, and a pore-forming material. The prepared slurry can be formed into a sheet on a PET film using the doctor blade method to form the lithium ion conductor porous layer 112 green sheet. At this time, the thickness of the lithium ion conductor porous layer 112 green sheet can be adjusted by adjusting the coating thickness. In addition, the porosity of the lithium ion conductor porous layer 112 can be controlled by adjusting the amount of pore-forming material added, and the pore size of the lithium ion conductor porous layer 112 can be controlled by adjusting the particle size of the pore-forming material.

[0045] (Preparation of the adhesive layer 12 green sheet) The adhesive layer 12 green sheet may be manufactured by any method, but for example it can be manufactured as follows. First, zirconia powder, lithium carbonate (Li ２ CO ３The adhesive layer slurry is prepared by mixing powder, dispersant, solvent, plasticizer, binder, and pore-forming agent. The prepared slurry can be formed into a sheet on a PET film using the doctor blade method to form the adhesive layer 12 green sheet. At this time, the thickness of the adhesive layer 12 green sheet can be adjusted by adjusting the coating thickness. Furthermore, the porosity of the adhesive layer 12 can be controlled by adjusting the amount of pore-forming agent added, and the pore size of the adhesive layer 12 can be controlled by adjusting the particle size of the pore-forming agent. By firing this green sheet, zirconia and lithium carbonate react to form an adhesive layer 12 containing lithium zirconate. Alternatively, lithium zirconate powder may be mixed directly.

[0046] (Preparation of the support substrate 13 green sheet) The support substrate 13 can be manufactured by any method, such as extrusion molding, tape molding, mold casting, or press molding. For example, in the case of tape molding, it can be manufactured as follows. First, a zirconia slurry is prepared by mixing zirconia powder, a dispersant, a solvent, a plasticizer, a binder, and a pore-forming agent. The prepared slurry is then formed into a sheet on a PET film using the doctor blade method to form a green sheet that will become the support substrate 13. At this time, the thickness of the support substrate 13 green sheet can be adjusted by adjusting the coating thickness. In addition, the porosity of the support substrate 13 can be controlled by adjusting the amount of pore-forming agent added, and the pore diameter of the support substrate 13 can be controlled by adjusting the particle size of the pore-forming agent.

[0047] (Cutting / Lamination) Each green sheet is cut, and a predetermined number of sheets are laminated and pressed together according to the thickness of each layer (cutting / lamination). Lamination can be performed by known methods and is not particularly limited, but a CIP (cold isostatic pressing) molding machine or a uniaxial press molding machine can be used. The preferred pressing pressure is 10 to 5000 kgf / cm ２ More preferably, 50 to 3000 kgf / cm² ２The structures shown in Figures 2 and 4 can be created by varying the type of green sheet used for layering. Figure 8 illustrates the manufacturing process for the lithium separation member 10 with the structure shown in Figure 2. Furthermore, the thickness of the lithium ion conductor dense layer 111, the lithium ion conductor porous layer 112, the adhesive layer 12, and the support substrate 13 can be controlled by adjusting the thickness and number of layers of each layer of green sheet.

[0048] (Firing) The laminated green sheets are then cut to a predetermined shape and size and fired (1150-1500°C, 1-10 hours). That is, the green sheets that will become the lithium ion conductor dense layer 111, the green sheets that will become the adhesive layer 12, and the green sheets that will become the support substrate 13 are all fired together (co-firing), and each becomes the lithium ion conductor dense layer 111, the adhesive layer 12, and the support substrate 13, respectively. In this way, a lithium separation member 10 can be manufactured in which the lithium ion conductor dense layer 111, the adhesive layer 12, and the support substrate 13 are laminated, for example, as shown in Figure 2. Furthermore, in the above example, the lithium separation member 10 was manufactured by laminating the green sheets of the lithium ion conductor dense layer 111, the adhesive layer 12, and the support substrate 13 and firing them together, but the lithium ion conductor dense layer 111, the adhesive layer 12, and the support substrate 13 may be manufactured by firing them sequentially or separately. Specifically, the green sheet that will form the adhesive layer 12 and the green sheet that will form the support substrate 13 are laminated together, and the green sheets that will form the adhesive layer 12 and the support substrate 13 are fired once to manufacture the adhesive layer 12 and the support substrate 13. Then, the green sheet that will form the lithium ion conductor dense layer 111 may be laminated onto the manufactured adhesive layer 12 and fired. Furthermore, the green sheet that will form the adhesive layer 12 may be laminated onto the support substrate 13 together with the green sheet that will form the lithium ion conductor dense layer 111 after the support substrate 13 has been manufactured and fired. Alternatively, the green sheet that will form the lithium ion conductor dense layer 111 and the green sheet that will form the adhesive layer 12 may be fired separately, and the manufactured lithium ion conductor dense layer 111, adhesive layer 12 and support substrate 13 may be joined together.

[0049] Figure 10 shows an example of a manufacturing method for the lithium separation member 10 of the second embodiment. Figure 10 illustrates the manufacturing of the lithium separation member 10 with the structure shown in Figure 6(a). The manufacturing method for the lithium separation member 10 shown in Figure 10 involves creating green sheets to form each layer, and then cutting and laminating them. At this time, the green sheets to form each layer are created in the same manner as in Figure 9, except that a por-forming agent is not added to the zirconia slurry for creating the support base material 13.

[0050] (Punching) After laminating the green sheets, multiple through holes 13h are formed in the laminate of green sheets that will form the base material 13 by punching. The size, arrangement, and shape of the openings 13k of the through holes 13h are determined by the die used for punching. Punching can be performed by any known method and is not particularly limited, but a punching machine or a press machine can be used.

[0051] (Lamination) Then, green sheets that will form the adhesive layer 12 and green sheets that will form the lithium-ion conductor dense layer 111 are laminated onto the laminate of green sheets that will form the base of the punched support substrate 13. At this time, the structures shown in Figures 6(a) to (b) can be created depending on the type of green sheet to be laminated. If through holes are to be provided in the adhesive layer 12, through holes can be formed by laminating the green sheet that will form the adhesive layer 12 together with the green sheet that will form the base of the support substrate 13 and then punching it out. Furthermore, the thickness of the lithium-ion conductor dense layer 111, the lithium-ion conductor porous layer 112, and the adhesive layer 12 can be controlled by adjusting the thickness of the green sheets in each layer and the number of layers.

[0052] (Firing) Next, the laminated green sheets are cut to a predetermined shape and size and fired (1150 to 1500°C, 1 to 10 hours). That is, the green sheets that will become the lithium ion conductor dense layer 111, the green sheets that will become the adhesive layer 12, and the green sheets that will become the support substrate 13 are all fired together, becoming the lithium ion conductor dense layer 111, the adhesive layer 12, and the support substrate 13, respectively. In this way, a lithium separation member 10 can be manufactured in which the lithium ion conductor dense layer 111 and the support substrate 13 are laminated, for example, as shown in Figure 6(a). Furthermore, in the above example, the lithium separation member 10 was manufactured by laminating the green sheets of the lithium ion conductor dense layer 111, the adhesive layer 12, and the support substrate 13 and firing them together, but the lithium ion conductor dense layer 111, the adhesive layer 12, and the support substrate 13 may be manufactured by firing them sequentially or separately.

[0053] In the above process, punching was performed after cutting / lamination, but there is also a method in which the green sheet that will become the support base material 13 is punched first, and then cutting / lamination is performed. In this case, the second lamination is unnecessary. Also, in the above process, through holes 13h were formed by punching, but this is not the only method. For example, through holes 13h can be formed by laser processing.

[0054] Figure 11 shows another example of the manufacturing method for the lithium separation member 10 of the second embodiment. Here, the manufacturing method for the lithium ion conductor dense layer 111 is the same, but the manufacturing method for the support substrate 13 is different, so only the manufacturing method for the support substrate 13 is shown before the lamination and firing processes. In Figure 11, the support substrate 13 is not made from a green sheet, but from a piece that has been extruded and cut.

[0055] (Extrusion molding, cutting) First, zirconia clay is prepared by kneading zirconia powder, a dispersant, a solvent, a plasticizer, and a binder. Then, this zirconia clay is put into an extrusion molding machine and a molded body is manufactured by extrusion molding through a square-shaped die. The die has an opening shape for forming multiple through holes 13h. The extrusion molding is carried out in a direction such that the direction in which the through holes 13h extend is horizontal. At this time, by making the shape of the die square, a rectangular parallelepiped molded body as shown in Figure 11 can be produced. After extrusion molding, it is cut to a predetermined length by a cutting means such as a wire cutter.

[0056] (Lamination and firing) After this, the process is the same as in Figure 10, and the green sheet that will become the adhesive layer 12 and the green sheet that will become the lithium ion conductor dense layer 111 are laminated onto the cut molded body and fired (1150 to 1500°C, 1 to 10 hours). Alternatively, the support base material 13 may be fired first, and the green sheet that will become the lithium ion conductor dense layer 111 and the green sheet that will become the adhesive layer 12 may be laminated onto the manufactured support base material 13 and fired, or the green sheet that will become the lithium ion conductor dense layer 111 and the green sheet that will become the adhesive layer 12 may be fired separately, and the manufactured lithium ion conductor dense layer 111, adhesive layer 12 and support base material 13 may be joined together. In this case, the extruded columnar support base material 13 may be fired and then cut to a predetermined thickness.

[0057] The manufacturing method for the lithium separation member 10 shown in Figures 9 to 11 can be understood as a manufacturing method for the lithium separation member 10 that includes: a first sheet creation step of creating a first sheet (in this case, a green sheet that will become the lithium ion conductor dense layer 111) which will be the basis of a lithium ion conductor dense layer 111 having a dense structure and containing a lithium ion conductor that selectively allows lithium ions to pass through; a second sheet creation step of creating a second sheet (in this case, a green sheet that will become the basis of the support base material 13) which will be the basis of a support base material 13 that will support the lithium ion conductor dense layer 111; a third sheet creation step of bonding the lithium ion conductor dense layer 111 and the support base material 13 to create a third sheet (in this case, a green sheet that will become the basis of the adhesive layer 12) which will be the basis of an adhesive layer 12 containing lithium zirconate; and a firing step of firing the first sheet, the second sheet, and the third sheet to form the lithium ion conductor dense layer 111, the support base material 13, and the adhesive layer 12.

[0058] Examples of the present invention will be described below. In these examples, lithium-ion conductive solid electrolyte ceramics (LLTO) were used as the lithium-ion conductor. The support substrate 13 was made of 3.0 mol% yttria-stabilized zirconia (3YSZ). Table 1 below shows the manufacturing conditions and evaluation results for Examples 1 to 15 and Comparative Examples 1 to 2.

[0059]

[0060] [Examples 1-13] In Examples 1-13, the lithium separation member 10 shown in Figure 2 was fabricated.

[0061] (Preparation of the green sheet that will become the lithium-ion conductor dense layer 111) First, an LLTO slurry was prepared by mixing LLTO powder, a dispersant, a solvent, a plasticizer, and a binder. The prepared LLTO slurry was formed into a sheet on a PET film using the doctor blade method to form a green sheet that will become the lithium-ion conductor dense layer 111. The thickness of this green sheet was set to 10 μm after firing.

[0062] (Preparation of the green sheet that will become the adhesive layer 12) First, an adhesive layer slurry was prepared by mixing zirconia powder, lithium carbonate powder, a dispersant, a solvent, a plasticizer, a binder, and polymethyl methacrylate beads as a pore-forming material. The prepared adhesive layer slurry was formed into a sheet on a PET film using the doctor blade method to form a green sheet that will become the adhesive layer 12. At this time, the thickness of the green sheet and the mixing ratio of zirconia powder and lithium carbonate powder were adjusted to create different examples 1 to 13. The upper limit of the thickness of each green sheet after firing was set to 100 μm, and if a thickness greater than this was required, the number of layers was increased. The thickness of the adhesive layer after firing and the lithium zirconate content are shown in Table 1. In Examples 8 and 9, the adhesive layer 12 was formed directly on the green sheet of the support substrate 13 by the printing method. In Examples 1 to 7, the thickness of the adhesive layer 12 was 10 μm, and the lithium zirconate content in the adhesive layer 12 was 5%, 10%, 20%, 30%, 50%, 80%, and 90%, respectively. In Examples 8 to 13, the lithium zirconate content in the adhesive layer 12 was 20%, and the thickness of the adhesive layer 12 was 1 μm, 5 μm, 20 μm, 50 μm, 100 μm, and 200 μm, respectively.

[0063] (Preparation of the green sheet that will become the support substrate 13) First, a zirconia slurry was prepared by mixing 3YSZ powder, a dispersant, a solvent, a plasticizer, a binder, and polymethyl methacrylate beads as a pore-forming material. The prepared zirconia slurry was formed into a sheet on a PET film using the doctor blade method to form the green sheet that will become the support substrate 13. The thickness of this green sheet was set to 200 μm after firing.

[0064] (Lamination, Pressing, and Firing) One green sheet to form the lithium-ion conductor dense layer 111, one green sheet to form the adhesive layer 12 (two and three sheets in Examples 10 and 10 respectively), and ten green sheets to form the support substrate 13 are stacked, and the resulting laminate is subjected to CIP (cold isostatic pressing) at 200 kgf / cm². ２The green sheets were pressed together to bond them to each other. The resulting laminate was then cut to a size of 50 mm x 50 mm after firing to obtain a rectangular laminate. The obtained rectangular laminate was fired at 1300°C for 2 hours in air to obtain the lithium separation member 10 shown in Figure 2.

[0065] [Examples 14-16] In Examples 14-16, the lithium separation member 10 shown in Figure 6(a) was fabricated.

[0066] [Examples 17-20] In Examples 17-20, the support substrate 13 was 4.0 mol% yttria-stabilized zirconia (4YSZ), 5.0 mol% yttria-stabilized zirconia (5YSZ), 6.0 mol% yttria-stabilized zirconia (6YSZ), and 8.0 mol% yttria-stabilized zirconia (8YSZ), respectively.

[0067] (Preparation of green sheets to form each layer) In Examples 14 to 16, green sheets to form each layer were prepared and cut / laminated. At this time, the green sheets to form each layer were prepared in the same manner as in Examples 1 to 13, except that a porosizing agent was not added to the zirconia slurry for creating the adhesive layer 12 and the support substrate 13. In Examples 14 to 16, the thickness of the adhesive layer 12 was set to 10 μm, and the lithium zirconate content in the adhesive layer 12 was set to 10%, 20%, and 50%, respectively. Then, multiple through holes 13h were formed in the laminate of green sheets to form the adhesive layer 12 and the support substrate 13 by punching. The shape of the through holes 13h was circular, and the size W1 of the opening 13k and the width W3 of the crossbar after firing were set to 2.5 mm and 0.5 mm, respectively.

[0068] (Lamination, Pressing, and Firing) One green sheet to form the lithium-ion conductor dense layer 111, one green sheet to form the adhesive layer 12, and ten green sheets to form the punched support substrate 13 are stacked, and the resulting laminate is subjected to CIP (cold isostatic pressing) at 200 kgf / cm². ２The green sheets were pressed together to bond them to each other. The bonded laminate was then cut to a size of 50 mm x 50 mm after firing to obtain a rectangular laminate. The obtained rectangular laminate was fired at 1300°C for 2 hours in air to obtain the lithium separation member 10 shown in Figure 6(a).

[0069] [Comparative Example 1] In Comparative Example 1, a lithium separation member was prepared in the same manner as in Example 1, except that the adhesive layer 12 was not provided. In this case, the lithium separation member has a structure similar to the lithium separation member 10 shown in Figure 2, but without the adhesive layer 12.

[0070] [Comparative Example 2] In Comparative Example 1, the lithium separation member was prepared in the same manner as in Example 14, except that the adhesive layer 12 was not provided. In this case, the lithium separation member has a structure in which the adhesive layer 12 is removed from the lithium separation member 10 shown in Figure 6(a).

[0071] (Evaluation Method) The cross-section of the obtained lithium separation member 10 was observed using an SEM to check for the presence or absence of microcracks in the adhesive layer 12. For Examples 1 to 16, those without microcracks were marked with ○, and those with microcracks were marked with △. Next, the adhesion between the lithium ion conductor layer 11 and the adhesive layer 12 was evaluated. Specifically, the interface between the lithium ion conductor layer 11 and the adhesive layer 12 was observed at a magnification of 2000x, and the length of contact and the length of the floating area between the lithium ion conductor layer 11 and the adhesive layer 12, i.e., the length of the region where pores exist, was calculated. The ratio of the floating length to the total length of contact and floating between the lithium ion conductor layer 11 and the adhesive layer 12 was calculated. The same ratio was calculated for the interface between the lithium ion conductor layer 11 and the support substrate 13 in the case of Comparative Example 1 or 2. For Examples 1 to 16, compared with Comparative Example 1 or 2, those with a decreased ratio were marked with ○, and those with a ratio of 0.8 or less were marked with ◎.

[0072] (Results) Examples 1 to 20 showed improved adhesion compared to Comparative Examples 1 to 2. Furthermore, Examples 2 to 20, in which the proportion of lithium zirconate in the adhesive layer 12 was 10% or more, showed further improved adhesion. In addition, Examples 1 to 6 and 8 to 20, in which the lithium zirconate content was 80% or less, were able to suppress the occurrence of initial fine cracks in the adhesive layer 12.

[0073] Although this embodiment has been described above, the technical scope of the present invention is not limited to the scope described in the above embodiment. It is clear from the claims that various modifications or improvements made to the above embodiment are also included in the technical scope of the present invention.

[0074] 1...Lithium separation device, 10...Lithium separation member, 11...Lithium ion conductor layer, 12...Adhesive layer, 13...Support substrate, 13h...Through hole, 13k...Opening, 13s...Frame, 111...Lithium ion conductor dense layer, 112...Lithium ion conductor porous layer

Claims

1. A lithium separation member comprising: a lithium ion conductor layer that selectively permeates lithium ions; a support substrate containing yttria-stabilized zirconia that supports the lithium ion conductor layer; and an adhesive layer containing lithium zirconate that adheres the lithium ion conductor layer and the support substrate.

2. The lithium separation member according to claim 1, wherein the lithium ion conductor layer is a dense lithium ion conductor layer having a dense structure.

3. The lithium separation member according to claim 2, wherein the lithium ion conductor layer includes, in addition to the lithium ion conductor dense layer, a lithium ion conductor porous layer disposed between the lithium ion conductor dense layer and the adhesive layer and having a porous structure.

4. The lithium separation member according to any one of claims 1 to 3, wherein the adhesive layer further comprises components constituting the lithium ion conductor layer.

5. The lithium separation member according to claim 1, wherein the support base material has a porous structure.

6. The lithium separation member according to claim 1, wherein the support base material has a dense structure having a plurality of through holes.

7. The lithium separation member according to claim 1, wherein the adhesive layer contains 10% to 80% lithium zirconate.

8. The lithium separation member according to claim 1, wherein the adhesive layer has a thickness of 200 μm or less.

9. The lithium separation member according to claim 1, wherein the shape is cylindrical.

10. A lithium separation apparatus comprising: a lithium separation member which is a member that selectively allows lithium ions to pass through; and a pair of electrodes arranged on each side of two main surfaces of the lithium separation member, wherein the lithium separation member comprises: a lithium ion conductor layer which selectively allows lithium ions to pass through; a support substrate which contains yttria-stabilized zirconia and supports the lithium ion conductor layer; and an adhesive layer which bonds the lithium ion conductor layer and the support substrate and contains lithium zirconate.

11. A method for manufacturing a lithium separation member, comprising: a first sheet preparation step of creating a first sheet that will be the basis for a lithium ion conductor dense layer having a dense structure and containing a lithium ion conductor that selectively permeates lithium ions; a second sheet preparation step of creating a second sheet that will be the basis for a support substrate that will support the lithium ion conductor dense layer and contains yttria-stabilized zirconia; a third sheet preparation step of bonding the lithium ion conductor dense layer and the support substrate to create a third sheet that will be the basis for an adhesive layer containing lithium zirconate; and a firing step of firing the first sheet, the second sheet and the third sheet to form the lithium ion conductor dense layer, the support substrate and the adhesive layer, respectively.

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