Zinc secondary battery

Abstract

The present application provides a zinc secondary battery (particularly, a laminated battery thereof) having excellent alkali resistance and capable of preventing zinc dendrite growth, with a simple structure that is easy to assemble and easy to collect. The zinc secondary battery has a battery element including: a positive electrode plate including a positive electrode active material layer and a positive electrode current collector; a negative electrode plate including a negative electrode active material layer containing zinc, and a negative electrode current collector; a layered double hydroxide (LDH)-like compound separator covering or enclosing the entire negative electrode active material layer; and an electrolyte. The positive electrode current collector has a positive electrode current collector tab extending from one edge of the positive electrode active material layer, and the negative electrode current collector has a negative electrode current collector tab extending from one edge of the negative electrode active material layer opposite the positive electrode current collector tab beyond the end of the LDH-like compound separator, so that the battery element can be collected from opposite sides by the positive electrode current collector tab and the negative electrode current collector tab. In addition, the outer edges of at least two edges of the LDH-like compound separator that are adjacent to each other (except for the one edge overlapping the negative electrode current collector tab) are closed.

Description

Technical Field

[0001] This invention relates to zinc secondary batteries. Background Technology

[0002] It is known that in zinc secondary batteries such as nickel-zinc batteries and zinc-air batteries, during charging, metallic zinc dendrites precipitate from the negative electrode, penetrating the gaps in the separator (such as non-woven fabric) to reach the positive electrode, resulting in a short circuit. Repeated short circuits caused by zinc dendrites will shorten the charge-discharge life.

[0003] To address the aforementioned problems, batteries incorporating layered double hydroxide (LDH) separators have been proposed, which selectively allow hydroxide ions to permeate while preventing zinc dendrites from penetrating. For example, Patent Document 1 (International Publication No. 2013 / 118561) discloses the placement of an LDH separator between the positive and negative electrodes in a nickel-zinc secondary battery. Furthermore, Patent Document 2 (International Publication No. 2016 / 076047) discloses a separator structure comprising an LDH separator fitted or bonded to a resin frame, and discloses that the LDH separator possesses high density, exhibiting a degree of air and / or water impermeability. This document also discloses that the LDH separator can be composited with a porous substrate. Additionally, Patent Document 3 (International Publication No. 2016 / 067884) discloses various methods for forming a dense LDH film on the surface of a porous substrate to obtain a composite material (LDH separator). The method includes the following steps: uniformly attaching a starting material that can provide the crystal growth starting point for LDH to a porous substrate; and performing hydrothermal treatment on the porous substrate in a raw material aqueous solution to form a dense LDH film on the surface of the porous substrate.

[0004] However, Patent Document 4 (International Publication No. 2019 / 077953) discloses a zinc secondary battery that includes a positive electrode plate, a negative electrode plate, an LDH separator and an electrolyte, and the battery elements can collect electricity from opposite sides of each other by means of the positive electrode current collector and the negative electrode current collector.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: International Publication No. 2013 / 118561

[0008] Patent Document 2: International Publication No. 2016 / 076047

[0009] Patent Document 3: International Publication No. 2016 / 067884

[0010] Patent Document 4: International Publication No. 2019 / 077953 Summary of the Invention

[0011] When using the LDH separator as described above to construct zinc secondary batteries such as nickel-zinc batteries, short circuits caused by zinc dendrites can be prevented. Furthermore, to maximize this effect, it is desirable to reliably separate the positive and negative electrodes using the LDH separator. In particular, it is extremely convenient if multiple positive and negative electrodes can be easily combined to assemble a stacked battery to ensure the above-mentioned configuration and obtain high voltage and high current. However, in conventional zinc secondary batteries, the separation of the positive and negative electrodes using the LDH separator is achieved by carefully and meticulously sealing the LDH separator and battery container using a resin frame, adhesive, etc., to ensure liquid tightness, which easily complicates the battery structure and manufacturing process. This complexity in battery structure and manufacturing process can be particularly significant when constructing a stacked battery. This is because it requires sealing each of the multiple individual cells constituting the stacked battery separately to ensure liquid tightness.

[0012] The inventors of this invention have recently realized that by using an LDH-like compound (described later) instead of conventional LDH as the hydroxide ion-conducting material, a hydroxide ion-conducting separator (LDH-like compound separator) with excellent alkali resistance and the ability to more effectively suppress short circuits caused by zinc dendrites can be provided. Furthermore, it has been realized that by employing an LDH-like compound separator that completely covers or encapsulates the negative electrode active material layer, and configured such that the positive and negative electrode current collectors extend in opposite directions, the complex sealing connection between the LDH-like compound separator and the battery container is unnecessary. This allows for a simple configuration that prevents zinc dendrite growth, enabling the provision of zinc secondary batteries (especially their stacked batteries) with a simple structure that facilitates easy assembly and current collection.

[0013] Therefore, the object of the present invention is to provide a zinc secondary battery (especially its stacked battery) with excellent alkali resistance and the ability to prevent zinc dendrite extension, in a simple configuration that is easy to assemble and easy to collect electricity.

[0014] According to one aspect of the present invention, a zinc secondary battery is provided, comprising the following battery elements:

[0015] A positive electrode plate, which includes a positive active material layer and a positive current collector;

[0016] A negative electrode plate comprising a negative electrode active material layer and a negative electrode current collector, wherein the negative electrode active material layer contains at least one of the following selected from the group consisting of zinc, zinc oxide, zinc alloys and zinc compounds.

[0017] A layered double hydroxide (LDH) compound separator, comprising an LDH compound and completely covering or encapsulating the negative electrode active material layer; and

[0018] Electrolyte

[0019] The zinc secondary battery is characterized in that...

[0020] The positive electrode active material layer, the negative electrode active material layer, and the LDH-like compound separator are all quadrilateral in shape.

[0021] The positive current collector has a positive current collector tab extending from one side of the positive active material layer, and the negative current collector has a negative current collector tab extending from one side of the negative active material layer opposite to the positive current collector tab, beyond the end of the LDH-like compound separator. Thus, the battery elements can collect electricity from opposite sides via the positive and negative current collector tabs.

[0022] Furthermore, the outer edges of at least two adjacent sides of the LDH-like compound separator (excluding the side that overlaps with the negative electrode collector tab) are closed. Attached Figure Description

[0023] Figure 1 This is a perspective view showing an example of the internal structure of the zinc secondary battery of the present invention.

[0024] Figure 2 It is a conceptual representation Figure 1 The diagram shows a simplified cross-sectional view of the layered structure of a zinc secondary battery.

[0025] Figure 3 express Figure 1 The appearance and internal structure of the zinc secondary battery are shown.

[0026] Figure 4A This is a perspective view of an example of a negative electrode plate in which the negative electrode active material layer used in the zinc secondary battery of the present invention is covered by an LDH-like compound separator.

[0027] Figure 4B It means Figure 4A The diagram shows a simplified cross-sectional view of the layers of the negative electrode plate.

[0028] Figure 5 It is used for explanation Figure 4A A schematic diagram of the region in the negative electrode plate covered by an LDH-like compound separator.

[0029] Figure 6A This is a conceptual diagram illustrating one example of the He transmittance measurement system used in Examples A1 to A5.

[0030] Figure 6B yes Figure 6A A simplified cross-sectional view of the sample holder and its surrounding components used in the measurement system shown.

[0031] Figure 7 This is a simplified cross-sectional view of the electrochemical measurement system used in Examples A1 to A5.

[0032] Figure 8A This is a surface SEM image of the LDH-like compound separator fabricated in Example A1.

[0033] Figure 8B The X-ray diffraction results are for the LDH-like compound separator fabricated in Example A1.

[0034] Figure 9A This is a surface SEM image of the LDH-like compound separator fabricated in Example A2.

[0035] Figure 9B The X-ray diffraction results are for the LDH-like compound separator fabricated in Example A2.

[0036] Figure 10A This is a surface SEM image of the LDH-like compound separator fabricated in Example A3.

[0037] Figure 10B The X-ray diffraction results are for the LDH-like compound separator fabricated in Example A3.

[0038] Figure 11A This is a surface SEM image of the LDH-like compound separator fabricated in Example A4.

[0039] Figure 11B The X-ray diffraction results are for the LDH-like compound separator fabricated in Example A4.

[0040] Figure 12A This is a surface SEM image of the LDH-like compound separator fabricated in Example A5.

[0041] Figure 12B The X-ray diffraction results are for the LDH-like compound separator fabricated in Example A5.

[0042] Figure 13A This is a surface SEM image of the LDH-like compound separator fabricated in Example A6.

[0043] Figure 13B The X-ray diffraction results are for the LDH-like compound separator fabricated in Example A6.

[0044] Figure 14 This is a surface SEM image of the LDH-like compound separator fabricated in Example A7.

[0045] Figure 15A This is a surface SEM image of the LDH partition fabricated in Example A8 (Comparison).

[0046] Figure 15B The X-ray diffraction results are for the LDH partition fabricated in Example A8 (Comparison).

[0047] Figure 16 This is a surface SEM image of the LDH-like compound separator fabricated in Example B1.

[0048] Figure 17 This is a surface SEM image of the LDH-like compound separator fabricated in Example C1.

[0049] Figure 18 This is a surface SEM image of the LDH-like compound separator fabricated in Example C2. Detailed Implementation

[0050] Zinc secondary battery

[0051] The zinc secondary battery of the present invention is any secondary battery that uses zinc as the negative electrode and employs an alkaline electrolyte (typically an aqueous solution of alkali metal hydroxides), and is not particularly limited thereto. Therefore, it can be a nickel-zinc secondary battery, a silver-zinc oxide secondary battery, a manganese-zinc oxide secondary battery, an air-zinc secondary battery, or various other alkaline zinc secondary batteries. For example, preferably, the positive electrode contains nickel hydroxide and / or nickel hydroxyl oxide, thereby forming a nickel-zinc secondary battery. Alternatively, the positive electrode can be an air electrode, thereby forming an air-zinc secondary battery.

[0052] Figures 1-3 An example of the zinc secondary battery of the present invention is shown in the figure. Figures 1-3The zinc secondary battery 10 shown includes battery elements 11, which include: a positive electrode plate 12, a negative electrode plate 16, a layered double hydroxide (LDH) compound separator 22, and an electrolyte (not shown). The positive electrode plate 12 includes a positive active material layer 13 and a positive current collector. The negative electrode plate 16 includes a negative active material layer 17 and a negative current collector 18. The negative active material layer 17 contains at least one compound selected from the group consisting of zinc, zinc oxide, zinc alloys, and zinc compounds. The LDH compound separator 22 completely covers or encloses the negative active material layer 17. It should be noted that in this specification, "LDH compound separator" refers to a separator containing an LDH compound and is defined as a component that specifically utilizes the hydroxide ion conductivity of the LDH compound to selectively allow hydroxide ions to pass through. Furthermore, "LDH-like compounds" are hydroxides and / or oxides with a layered crystalline structure that cannot be called LDH but resemble LDH, and are defined as compounds from which no peaks originating from LDH can be detected by X-ray diffraction. The positive electrode active material layer 13, the negative electrode active material layer 17, and the LDH-like compound separator 22 are all quadrilateral in shape (typically quadrilateral). The positive electrode current collector has a positive electrode tab 14a extending from one side of the positive electrode active material layer 13, and the negative electrode current collector 18 has a negative electrode tab 18a extending from one side of the negative electrode active material layer 17 opposite to the positive electrode tab 14a, beyond the end of the LDH-like compound separator 22. As a result, the battery element 11 can collect electricity from opposite sides using the positive electrode tab 14a and the negative electrode tab 18a. Based on this, the outer edges of at least two adjacent sides C of the LDH-like compound separator 22 (except for the side that overlaps with the negative electrode current collector tab) are closed. By employing an LDH-like compound separator 22 that completely covers or encloses the negative electrode active material layer 17, and configuring it such that the positive electrode current collector tab 14a and the negative electrode current collector tab 18a extend in opposite directions, the complicated sealing connection between the LDH-like compound separator 22 and the battery container is not required. A simple configuration that prevents zinc dendrite growth can be provided with a zinc secondary battery (especially its stacked battery) that is easy to assemble and easy to collect current. Furthermore, by using an LDH-like compound instead of conventional LDH as the hydroxide ion-conducting material, a hydroxide ion-conducting separator (LDH-like compound separator) with excellent alkali resistance and the ability to more effectively suppress short circuits caused by zinc dendrites, and a zinc secondary battery with such advantages, can be provided.

[0053] In other words, as described above, in conventional zinc secondary batteries, the positive and negative electrodes are separated using an LDH compound separator in a way that ensures liquid tightness by cleverly and carefully sealing the LDH compound separator and the battery container together using a resin frame, adhesive, etc., which easily complicates the battery structure and manufacturing process. This complexity in battery structure and manufacturing process can be particularly significant when constructing a stacked battery. In this regard, in the zinc secondary battery 10 of the present invention, since the entire negative electrode active material layer 17 is covered or encased by an LDH compound-like separator 22, the negative electrode plate 16 covered or encased by the LDH compound-like separator 22 itself has the function of preventing short circuits caused by zinc dendrites. Therefore, by simply stacking the positive electrode plate 12 and the negative electrode plate 16 (which are covered or encased by the LDH compound-like separator 22), it is possible to separate the positive electrode plate 12 and the negative electrode plate 16 using an LDH compound-like separator. Furthermore, by configuring the positive current collector tab 14a and the negative current collector tab 18a to extend in opposite directions, a structure that facilitates current collection is obtained, reliably preventing accidental contact between the positive current collector and the negative current collector 18a. In particular, when manufacturing a stacked battery with multiple individual cells, the desired configuration can be achieved simply by alternately stacking the positive plate 12 and the negative plate 16, which is extremely advantageous. This is because the previously required ingenious and careful sealing joint to separate the positive and negative electrodes using an LDH compound separator is unnecessary. In the case of this stacked battery, multiple positive current collector tabs 14a can be bundled and connected to one positive current collector plate 14b or positive terminal 14c, and multiple negative current collector tabs 18a can be bundled and connected to one negative current collector plate 18b or negative terminal 18c, making current collection particularly easy.

[0054] Battery element 11 includes: positive electrode plate 12, negative electrode plate 16, LDH-like compound separator 22, and electrolyte (not shown).

[0055] The positive electrode plate 12 includes a positive electrode active material layer 13. The positive electrode active material layer 13 can be made of any known positive electrode material, depending on the type of zinc secondary battery, and is not particularly limited. For example, in the case of a nickel-zinc secondary battery, a positive electrode containing nickel hydroxide and / or nickel hydroxide oxide can be used. Alternatively, in the case of an air-zinc secondary battery, an air electrode can be used as the positive electrode. The positive electrode plate 12 also includes a positive electrode current collector (not shown), which has a positive electrode current collector tab 14a extending from one side of the positive electrode active material layer 13. A preferred example of the positive electrode current collector is a nickel-based porous substrate such as a foamed nickel plate. In this case, for example, a paste containing an electrode active material such as nickel hydroxide is uniformly coated onto the nickel-based porous substrate and dried, thereby ideally producing a positive electrode plate composed of a positive electrode / positive electrode current collector. At this time, it is also preferable to apply a pressing treatment to the dried positive electrode plate (i.e., the positive electrode / positive electrode current collector) to prevent the electrode active material from falling off and to increase the electrode density. It should be explained that Figure 2 The positive electrode plate 12 shown includes a positive current collector (e.g., foamed nickel), but is not illustrated. This is because the positive current collector is integrally integrated with the positive active material layer 13, making it impossible to depict the positive current collector separately. The zinc secondary battery 10 preferably also includes a positive current collector plate 14b connected to the end of the positive current collector tab 14a; more preferably, multiple positive current collector tabs 14a are connected to one positive current collector plate 14b. Accordingly, current collection can be efficiently achieved with a simple structural space, and it is also easy to connect to the positive terminal 14c. Furthermore, the positive current collector plate 14b itself can be used as the positive terminal.

[0056] The negative electrode plate 16 includes a negative electrode active material layer 17. The negative electrode active material layer 17 contains at least one material selected from the group consisting of zinc, zinc oxide, zinc alloys, and zinc compounds. That is, zinc only needs to have suitable electrochemical activity for the negative electrode, and it can be contained therein in any form of zinc metal, zinc compound, or zinc alloy. Preferred examples of negative electrode materials include zinc oxide, metallic zinc, and calcium zincate, with a mixture of metallic zinc and zinc oxide being more preferred. The negative electrode active material layer 17 can be configured as a gel or mixed with an electrolyte to form a negative electrode mixture. For example, by adding an electrolyte and a thickener to the negative electrode active material, a negative electrode that is easily gelled can be obtained. Examples of thickeners include polyvinyl alcohol, polyacrylate, CMC, and alginate; polyacrylate is preferred because it exhibits excellent chemical resistance to strong alkalis.

[0057] As the zinc alloy, zinc alloys that are known to be mercury-free and lead-free can be used. For example, zinc alloys containing 0.01 to 0.1% by mass of indium, 0.005 to 0.02% by mass of bismuth, and 0.0035 to 0.015% by mass of aluminum have the effect of suppressing hydrogen production and are therefore preferred. In particular, indium or bismuth improves discharge performance, which is advantageous. Regarding the use of zinc alloys as the negative electrode, by slowing down the self-dissolution rate in the alkaline electrolyte, hydrogen production can be suppressed, thereby improving safety.

[0058] The shape of the negative electrode material is not particularly limited, but it is preferably in powder form, which increases the surface area and enables it to handle high-current discharge. In the case of zinc alloy, the preferred negative electrode material has an average particle size in the range of 3 to 100 μm in terms of minor diameter. If it is within this range, the surface area is large, which is suitable for handling high-current discharge. Furthermore, it is easy to mix uniformly with the electrolyte and gelling agent, and the handling during battery assembly is also good.

[0059] The negative electrode plate 16 also includes a negative current collector 18, which has a negative current collector tab 18a extending from one side of the negative electrode active material layer 17 opposite to the positive current collector tab 14a beyond the end of the LDH-like compound separator 22. As a result, the battery element 11 can collect current from opposite sides of each other by means of the positive current collector tab 14a and the negative current collector tab 18a. The zinc secondary battery 10 preferably also includes a negative current collector plate 18b connected to the end of the negative current collector tab 18a, and more preferably multiple negative current collector tabs 18a are connected to one negative current collector plate 18b. Accordingly, current collection can be carried out efficiently with a simple configuration space, and it is also easy to connect to the negative terminal 18c. In addition, the negative current collector plate 18b itself can be used as the negative terminal. Typically, the end portion of the negative current collector tab 18a is formed as an exposed portion not covered by the LDH-like compound separator 22 and (sometimes present) liquid-retaining member 20. Accordingly, the negative current collector 18 (especially the negative current collector tab 18a) can be ideally connected to the negative current collector plate 18b and / or the negative terminal 18c by means of the exposed portion. In this case, such as Figure 5 As shown, the preferred type of LDH compound separator 22 is covered or enclosed with a predetermined margin M (e.g., a spacing of 1 to 5 mm) to fully conceal the end of the negative electrode active material layer 17 on the negative electrode current collector tab 18a side. This more effectively prevents zinc dendrites from extending from or near the end of the negative electrode active material layer 17 on the negative electrode current collector tab 18a side.

[0060] As a preferred example of the negative electrode current collector 18, copper foil, copper mesh, and perforated copper mesh can be used, with copper mesh being more preferred. In this case, for example, a mixture containing zinc oxide powder and / or zinc powder, and a binder (e.g., polytetrafluoroethylene particles) of desired composition can be coated onto the copper mesh to ideally produce a negative electrode plate composed of a negative electrode / negative electrode current collector. Furthermore, it is preferable to apply a pressing treatment to the dried negative electrode plate (i.e., the negative electrode / negative electrode current collector) to prevent the electrode active material from falling off and to increase the electrode density.

[0061] The zinc secondary battery 10 preferably also includes a liquid-retaining component 20, which is located between the negative electrode active material layer 17 and the LDH-like compound separator 22, and completely covers or encapsulates the negative electrode active material layer 17. This ensures that the electrolyte is present between the negative electrode active material layer 17 and the LDH-like compound separator 22 without any leakage, thereby enabling efficient transfer of hydroxide ions between the negative electrode active material layer 17 and the LDH-like compound separator 22. The liquid-retaining component 20 is not particularly limited to any component capable of retaining the electrolyte, but is preferably a sheet-like component. Preferred examples of the liquid-retaining component include non-woven fabric, absorbent resin, liquid-retaining resin, porous sheets, and various spacers. Non-woven fabric is particularly preferred because it allows for the low-cost fabrication of a high-performance negative electrode structure. The thickness of the electrolyte retention component 20 is preferably 0.01 to 0.20 mm, more preferably 0.02 to 0.20 mm, even more preferably 0.02 to 0.15 mm, particularly preferably 0.02 to 0.10 mm, and most preferably 0.02 to 0.06 mm. A thickness within the above range allows for a compact and efficient overall structure of the negative electrode, and ensures that a sufficient amount of electrolyte is retained within the electrolyte retention component 20.

[0062] The entire negative electrode active material layer 17 is covered or enclosed by an LDH-like compound separator 22. Figure 4A and Figure 4B The diagram shows a preferred embodiment of a negative electrode plate 16 in which the negative electrode active material layer 17 is covered or enclosed by an LDH-like compound separator 22. Figure 4A and Figure 4B The shown negative electrode structure includes: a negative electrode active material layer 17, a negative electrode current collector 18, and a liquid-retaining component 20 as desired. The entire negative electrode active material layer 17 (as needed, separated by the liquid-retaining component 20) is covered or enclosed by an LDH-like compound separator 22. By covering or enclosing the entire negative electrode active material layer 17 (as needed, separated by the liquid-retaining component 20) with an LDH-like compound separator 22 in this way, as mentioned above, the cumbersome sealing connection between the LDH-like compound separator 22 and the battery container is not required. This allows for the extremely simple and highly productive production of zinc secondary batteries (especially their stacked batteries) that prevent zinc dendrite growth.

[0063] Figure 4A and Figure 4B In this design, the liquid-retaining component 20 is depicted as being smaller than the LDH-like compound separator 22. However, the liquid-retaining component 20 can be the same size as the LDH-like compound separator 22 (or a bent LDH-like compound separator 22), and the outer edge of the liquid-retaining component 20 can reach the outer edge of the LDH-like compound separator 22. That is, it can be configured such that the outer peripheral portion of the liquid-retaining component 20 is sandwiched between the LDH-like compound separators 22 constituting the outer peripheral portion. Accordingly, the outer edge of the LDH-like compound separator 22, described later, can be effectively sealed using heat fusion or ultrasonic welding. That is, compared to directly heat fusion or ultrasonic welding the LDH-like compound separators 22 to each other, when the heat-welding liquid-retaining component 20 is placed between the LDH-like compound separators 22 for indirect heat fusion or ultrasonic welding, the heat-welding property of the liquid-retaining component 20 itself can be utilized, resulting in a more effective seal. For example, the end of the liquid-retaining component 20 to be sealed can be used like hot melt adhesive. As a preferred example of the liquid-retaining component 20 at this time, non-woven fabrics, especially non-woven fabrics made of thermoplastic resins (such as polyethylene and polypropylene), can be cited.

[0064] The LDH-like compound separator 22 comprises an LDH-like material and a porous substrate. As described above, the LDH-like material seals the pores of the porous substrate, thereby enabling the LDH-like compound separator 22 to exhibit hydroxide ion conductivity and air impermeability (thus functioning as an LDH-like compound separator exhibiting hydroxide ion conductivity). The porous substrate is preferably made of a polymer material, and the LDH-like material is particularly preferably embedded throughout the thickness direction of the porous substrate made of polymer material. Various preferred embodiments of the LDH-like compound separator 22 will be described in detail below.

[0065] Regarding the number of LDH-like compound separators 22 for a single negative electrode active material layer 17, typically there is one on one side (two opposite sides or one bent on both sides), but there can also be more than two. For example, it can be configured such that the negative electrode active material layer 17 (which can be covered or enclosed by the liquid-retaining component 20) is completely covered or enclosed by multiple overlapping LDH-like compound separators 22.

[0066] As described above, the LDH-like compound separator 22 has a quadrilateral shape (typically a square). Furthermore, the outer edges of at least two adjacent edges C of the LDH-like compound separator 22 (excluding the edge overlapping with the negative electrode current collector 18a) are closed. Accordingly, the negative electrode active material layer 17 can be reliably isolated relative to the positive electrode plate 12, thereby more effectively preventing zinc dendrite extension. It should be noted that excluding the edge C overlapping with the negative electrode current collector 18a allows the negative electrode current collector 18a to extend outwards.

[0067] According to a preferred embodiment of the present invention, the battery element 11 is arranged such that the positive electrode plate 12, the negative electrode plate 16, and the LDH-like compound separator 22 are each longitudinally arranged, with one side C of the closed outer edge of the LDH-like compound separator 22 being the lower end. As a result, the positive electrode current collector 14a and the negative electrode current collector 18a extend laterally from opposite sides of the battery element 11. Accordingly, current collection is further facilitated, and when the upper edge of the outer edge of the LDH-like compound separator 22 is left open (described below), since there are no obstructions in the upper open portion, gas can flow in and out between the positive electrode plate 12 and the negative electrode plate 16 more easily.

[0068] However, one or two edges of the outer edge of the LDH-like compound separator 22 can be left open. For example, even if only the upper edge of the outer edge of the LDH-like compound separator 22 is left open, if the electrolyte is injected during the manufacture of the zinc secondary battery in a manner that prevents the electrolyte from reaching the upper edge, then since there is no electrolyte on that upper edge, problems such as leakage and zinc dendrite extension can be avoided. Relatedly, the battery element 11 and the positive electrode plate 12 are housed together in a housing 28 that can serve as a sealed container, and are sealed with a cover 26 as desired, thereby functioning as the main component of a sealed zinc secondary battery. Therefore, as long as the airtightness is ensured in the final housing 28, the battery element 11 itself can be a simple configuration with an open upper part. In addition, by leaving one edge of the outer edge of the LDH-like compound separator 22 open, the negative electrode current collector tab 18a can also extend from there.

[0069] The outer edge of the upper side of the LDH-like compound separator 22 is preferably open. This open-top configuration can address the problem of overcharging in nickel-zinc batteries, etc. That is, if overcharging occurs in nickel-zinc batteries, oxygen (O2) may be generated at the positive electrode plate 12. However, the LDH-like compound separator 22 has a high density that allows only hydroxide ions to pass through, so O2 cannot pass through. In this respect, according to the open-top configuration, O2 can escape upwards from the positive electrode plate 12 within the casing 28 and be introduced to the negative electrode plate 16 side through the open top portion, thereby allowing the O2 to oxidize the Zn in the negative electrode active material layer 17, turning it back into ZnO. Through such an oxygen reaction cycle, the overcharge tolerance can be improved by using the open-top battery element 11 in a sealed zinc secondary battery. It should be noted that even if the outer edge of the upper edge of the LDH-like compound separator 22 is closed, the same effect as the open configuration described above can be expected by providing a vent hole in a portion of the closed outer edge. For example, a vent hole can be provided after sealing the outer edge of the upper edge of the LDH-like compound separator 22, or a portion of the outer edge can be left unsealed during sealing in the manner of forming a vent hole.

[0070] In summary, it is preferable to achieve the closed edge C of the LDH compound separator 22 by bending the LDH compound separator 22 and / or sealing the LDH compound separator 22 with each other. Preferred examples of sealing methods include adhesives, heat sealing, ultrasonic sealing, tape, sealing strips, and combinations thereof. In particular, the LDH compound separator 22, which includes a porous substrate made of polymer material, is flexible and therefore has the advantage of being easy to bend. Therefore, it is preferable to form the LDH compound separator 22 into a long strip and bend it to form a closed edge C. Heat sealing and ultrasonic sealing can be performed using commercially available heat sealing machines, etc. In the case of sealing the LDH compound separator 22 with each other, if the outer peripheral portion of the liquid-retaining component 20 is sandwiched between the LDH compound separator 22 constituting the outer peripheral portion for heat sealing and ultrasonic sealing, a more effective seal can be achieved, which is ideal. On the other hand, commercially available adhesives, tapes, and sealing tapes are sufficient. To prevent deterioration in alkaline electrolytes, adhesives containing alkali-resistant resins are preferred. From this perspective, preferred examples of adhesives include epoxy resin-based adhesives, natural resin-based adhesives, modified olefin resin-based adhesives, and modified silicone resin-based adhesives. Among these, epoxy resin-based adhesives are particularly advantageous due to their excellent alkali resistance. An example of an epoxy resin-based adhesive is the epoxy adhesive Hysol (registered trademark) (manufactured by Henkel).

[0071] The electrolyte preferably contains an aqueous solution of an alkali metal hydroxide. The electrolyte is not shown because it permeates the entirety of the positive electrode plate 12 (particularly the positive electrode active material layer 13) and the negative electrode plate 16 (particularly the negative electrode active material layer 17). Examples of alkali metal hydroxides include potassium hydroxide, sodium hydroxide, lithium hydroxide, and ammonium hydroxide, with potassium hydroxide being more preferred. To suppress the self-dissolution of zinc and / or zinc oxide, zinc compounds such as zinc oxide and zinc hydroxide can be added to the electrolyte. As described above, the electrolyte can be mixed with the positive electrode active material and / or negative electrode active material to exist in the form of a positive electrode compound and / or a negative electrode compound. Furthermore, to prevent electrolyte leakage, the electrolyte can be gelled. As a gelling agent, a polymer that swells by absorbing the solvent of the electrolyte is preferred; polymers such as polyethylene oxide, polyvinyl alcohol, and polyacrylamide, and starch can be used.

[0072] like Figure 3 As shown, the zinc secondary battery 10 can further include a housing 28 for storing the battery elements 11. Furthermore, the number of battery elements 11 is two or more, and these two or more battery elements 11 can be stored together in the housing 28. This is a configuration known as a battery pack or stacked battery, which is advantageous in terms of obtaining high voltage and high current. The housing 28 for storing the battery elements 11 is preferably made of resin. The resin constituting the housing 28 is preferably a resin with resistance to alkali metal hydroxides such as potassium hydroxide, more preferably a polyolefin resin, ABS resin, or modified polyphenylene ether, and even more preferably ABS resin or modified polyphenylene ether. Additionally, a housing assembly formed by arranging two or more housings 28 can be housed within a casing to form a battery module.

[0073] LDH-like compound separator

[0074] The LDH-like compound separator is a separator containing a layered double hydroxide (LDH) compound. When assembled in a zinc secondary battery, it isolates the positive and negative plates in a manner that enables the conduction of hydroxide ions. That is, the LDH-like compound separator functions as a hydroxide ion conducting separator. Preferably, the LDH-like compound separator is airtight and / or watertight. In other words, the LDH-like compound separator is preferably densified to a degree of airtightness and / or watertightness. It should be noted that, in this specification, "airtightness" means that, as described in Patent Documents 2 and 3, even when helium gas is brought into contact with one side of the test object in water at a differential pressure of 0.5 atm, no bubbles generated by the helium gas are observed from the other side. Furthermore, in this specification, "watertightness" means that, as described in Patent Documents 2 and 3, water in contact with one side of the test object does not permeate to the other side. In other words, the impermeability of LDH-like compound separators to air and / or water means that they possess a high degree of density that prevents gas or water from passing through, and that they are not porous films or other porous materials that are permeable to water or air. Therefore, due to their hydroxide ion conductivity, LDH-like compound separators allow only selective permeation of hydroxide ions, thus fulfilling their function as battery separators. This configuration is therefore extremely effective in preventing short circuits between the positive and negative electrodes by physically preventing separator penetration caused by zinc dendrites generated during charging. Because of the hydroxide ion conductivity of the LDH-like compound separator, efficient movement of the required hydroxide ions between the positive and negative electrodes can be achieved, thereby enabling the charge-discharge reactions of both the positive and negative electrodes.

[0075] The He permeability per unit area of ​​the LDH-like compound separator is preferably 3.0 cm / min·atm or less, more preferably 2.0 cm / min·atm or less, and even more preferably 1.0 cm / min·atm or less. A separator with a He permeability of 3.0 cm / min·atm or less can extremely effectively suppress the permeation of Zn (typically zinc ions or zincate ions) in the electrolyte. Based on this principle, it can be considered that the separator of this design significantly suppresses Zn permeation in the manner described above, thereby effectively suppressing the growth of zinc dendrites when used in zinc secondary batteries. The He permeability is measured by the following steps: supplying He gas to one side of the separator and allowing the He gas to permeate through the separator; and calculating the He permeability and evaluating the compactness of the hydroxide ion-conducting separator. The He permeability is calculated using the He gas permeation rate F per unit time, the differential pressure P applied to the separator during He gas permeation, and the membrane area S through which the He gas permeates, according to the formula F / (P×S). By evaluating the permeability using He gas, it is possible to assess whether an extremely high level of tightness is achieved. Consequently, it is possible to effectively evaluate high tightness that minimizes the permeability of substances other than hydroxide ions (especially Zn, which causes zinc dendrite growth) (permeating only in extremely small amounts). This is because He gas has the smallest constituent unit among the diverse atoms or molecules that can constitute a gas, and its reactivity is extremely low. That is, He does not form molecules but constitutes He gas as He atom monomers. In this respect, since hydrogen gas is composed of H2 molecules, He atom monomers are smaller as gas constituent units. Since H2 gas is a flammable gas, it is more dangerous. Furthermore, by using an index such as He gas permeability defined by the above formula, an objective evaluation of tightness can be easily performed regardless of the sample size or measurement conditions. Therefore, it is possible to easily, safely, and effectively evaluate whether a separator has sufficiently high tightness suitable for zinc secondary batteries. It is preferable to measure the He permeability in the order shown in Evaluation 5 of the following embodiment.

[0076] In the LDH-like compound separator of the present invention, the LDH-like compound seals the pores of the porous substrate, preferably completely sealing the pores of the porous substrate. Preferably, the LDH-like compound is (a), (b), or (c).

[0077] (a) A layered crystalline hydroxide and / or oxide containing Mg and at least one element selected from the group consisting of Ti, Y and Al, that contains at least Ti.

[0078] (b) comprising (i) Ti, Y, and Al and / or Mg as desired, and (ii) at least one layered crystalline hydroxide and / or oxide selected from the group consisting of In, Bi, Ca, Sr and Ba, i.e., with added element M.

[0079] (c) Hydroxides and / or oxides containing Mg, Ti, Y, and, as desired, Al and / or In, with a layered crystalline structure.

[0080] In (c), the LDH-like compound exists in the form of a mixture with In(OH)3.

[0081] According to a preferred embodiment (a) of the invention, the LDH-like compound can be a layered crystalline hydroxide and / or oxide containing Mg and at least one element selected from the group consisting of Ti, Y, and Al. Therefore, a typical LDH-like compound is a complex hydroxide and / or complex oxide of Mg, Ti, Y (if desired), and Al (if desired). The aforementioned elements can be replaced by other elements or ions to the extent that the fundamental properties of the LDH-like compound are not impaired; however, the LDH-like compound preferably does not contain Ni. For example, the LDH-like compound may further contain Zn and / or K. Accordingly, the ionic conductivity of the LDH-like compound separator can be further improved.

[0082] LDH-like compounds can be identified using X-ray diffraction. Specifically, when X-ray diffraction is performed on the surface of the LDH-like compound separator, peaks originating from the LDH-like compound are typically detected in the range of 5° ≤ 2θ ≤ 10°, and more typically in the range of 7° ≤ 2θ ≤ 10°. As mentioned above, LDH is a substance having an alternating layered structure with exchangeable anions and H2O as intermediate layers between stacked hydroxide base layers. In this respect, when LDH is determined by X-ray diffraction, peaks originating from the crystalline structure of LDH (i.e., the (003) peak of LDH) are typically detected at a position of 2θ = 11 to 12°. In contrast, when LDH-like compounds are determined by X-ray diffraction, peaks are typically detected in the range of the aforementioned range, which is shifted to a lower angle than the aforementioned peak position of LDH. Furthermore, using 2θ corresponding to the peaks originating from the LDH-like compound in X-ray diffraction, the interlayer distance of the layered crystalline structure can be determined according to the Bragg formula. The interlayer distances of the layered crystal structures that constitute LDH-like compounds are typically 0.883–1.8 nm, and more typically 0.883–1.3 nm.

[0083] Regarding the LDH-like compound separator of the above-described scheme (a), the atomic ratio of Mg / (Mg+Ti+Y+Al) in the LDH-like compound, determined by energy dispersive X-ray analysis (EDS), is preferably 0.03 to 0.25, more preferably 0.05 to 0.2. Furthermore, the atomic ratio of Ti / (Mg+Ti+Y+Al) in the LDH-like compound is preferably 0.40 to 0.97, more preferably 0.47 to 0.94. Additionally, the atomic ratio of Y / (Mg+Ti+Y+Al) in the LDH-like compound is preferably 0 to 0.45, more preferably 0 to 0.37. Moreover, the atomic ratio of Al / (Mg+Ti+Y+Al) in the LDH-like compound is preferably 0 to 0.05, more preferably 0 to 0.03. Within these ranges, the alkali resistance is superior, and the effect of suppressing short circuits caused by zinc dendrites (i.e., dendrite tolerance) can be achieved more effectively. However, regarding LDH separators, the basic composition of LDH, as previously known, can be expressed by the general formula: M 2+ 1－x M 3+ x (OH)2A n－ x / n ·mH2O (where M) 2+ M is a divalent cation. 3+ A is a trivalent cation. n－ The term "anion with an n-valence, where n is an integer greater than or equal to 1, x is 0.1 to 0.4, and m is 0 or greater" is used. In contrast, the atomic ratios in LDH-like compounds generally deviate from the general formula for LDH. Therefore, it can be said that the LDH-like compounds in this scheme generally have different compositional ratios (atomic ratios) than conventional LDH. It should be noted that EDS analysis is preferably performed as follows: using an EDS analysis apparatus (e.g., X-act, manufactured by Oxford Instruments), 1) images are acquired at an accelerating voltage of 20 kV and a magnification of 5,000x; 2) in point analysis mode, with intervals of approximately 5 μm, three-point analysis is performed; 3) steps 1) and 2) are repeated once more; 4) the average value of the six points is calculated.

[0084] According to another preferred embodiment (b) of the invention, the LDH-like compound can be a layered crystalline hydroxide and / or oxide comprising (i) Ti, Y, and, depending on the desired inclusion of Al and / or Mg, and (ii) an additive element M. Thus, a typical LDH-like compound is a complex hydroxide and / or complex oxide comprising Ti, Y, an additive element M, and, depending on the desired inclusion of Al and Mg. The additive element M is In, Bi, Ca, Sr, Ba, or a combination thereof. The aforementioned elements can be substituted by other elements or ions to the extent that they do not impair the essential properties of the LDH-like compound; however, the LDH-like compound preferably does not contain Ni.

[0085] Regarding the LDH-like compound separator of scheme (b) above, the atomic ratio of Ti / (Mg+Al+Ti+Y+M) in the LDH-like compound, as determined by energy dispersive X-ray diffraction (EDS), is preferably 0.50 to 0.85, more preferably 0.56 to 0.81. The atomic ratio of Y / (Mg+Al+Ti+Y+M) in the LDH-like compound is preferably 0.03 to 0.20, more preferably 0.07 to 0.15. The atomic ratio of M / (Mg+Al+Ti+Y+M) in the LDH-like compound is preferably 0.03 to 0.35, more preferably 0.03 to 0.32. The atomic ratio of Mg / (Mg+Al+Ti+Y+M) in the LDH-like compound is preferably 0 to 0.10, more preferably 0 to 0.02. Furthermore, the atomic ratio of Al / (Mg+Al+Ti+Y+M) in the LDH-like compound is preferably 0 to 0.05, more preferably 0 to 0.04. Within the aforementioned range, the alkali resistance is even better, and it can more effectively suppress short circuits caused by zinc dendrites (i.e., dendrite tolerance). However, regarding LDH separators, the previously known basic composition of LDH can be expressed by the general formula: M 2+ 1－x M 3+ x (OH)2A n－ x / n ·mH2O (where M) 2+ M is a divalent cation. 3+ A is a trivalent cation. n－ The term "anion with an n-valence, where n is an integer greater than or equal to 1, x is 0.1 to 0.4, and m is 0 or greater" is used. In contrast, the atomic ratios in LDH-like compounds generally deviate from the general formula for LDH. Therefore, it can be said that the LDH-like compounds in this scheme generally have different compositional ratios (atomic ratios) than conventional LDH. It should be noted that EDS analysis is preferably performed as follows: using an EDS analysis apparatus (e.g., X-act, manufactured by Oxford Instruments), 1) images are acquired at an accelerating voltage of 20 kV and a magnification of 5,000x; 2) in point analysis mode, with intervals of approximately 5 μm, three-point analysis is performed; 3) steps 1) and 2) are repeated once more; 4) the average value of the six points is calculated.

[0086] According to another preferred embodiment (c) of the invention, the LDH-like compound can be a layered crystalline hydroxide and / or oxide containing Mg, Ti, Y, and, as desired, Al and / or In, and the LDH-like compound exists in the form of a mixture with In(OH)3. The LDH-like compound of this embodiment is a layered crystalline hydroxide and / or oxide containing Mg, Ti, Y, and, as desired, Al and / or In. Therefore, a typical LDH-like compound is a complex hydroxide and / or complex oxide of Mg, Ti, Y, and, as desired, Al, and, as desired, In. It should be noted that the In that may be contained in the LDH-like compound can be intentionally added to the LDH-like compound or unavoidably mixed into the LDH-like compound due to the formation of In(OH)3, etc. The above-mentioned elements can be replaced by other elements or ions to the extent that they do not impair the basic properties of the LDH-like compound; however, the LDH-like compound preferably does not contain Ni. However, regarding the LDH separator, the basic composition of the previously known LDH can be expressed by the general formula: M 2+ 1－x M 3+ x (OH)2A n－ x / n ·mH2O (where M) 2+ M is a divalent cation. 3+ A is a trivalent cation. n－ (where n is an n-valent anion, n is an integer greater than or equal to 1, x is 0.1 to 0.4, and m is 0 or greater). In contrast, the atomic ratios in LDH-like compounds generally deviate from the above general formula for LDH. Therefore, it can be said that the LDH-like compounds in this scheme generally have different compositional ratios (atomic ratios) than conventional LDHs.

[0087] The mixture in scheme (c) above contains not only an LDH-like compound but also In(OH)3 (typically composed of an LDH-like compound and In(OH)3). The presence of In(OH)3 effectively improves the alkali resistance and dendrite resistance of the LDH-like compound separator. The preferred proportion of In(OH)3 in the mixture is one that improves alkali resistance and dendrite resistance with minimal impairment of the hydroxide ion conductivity of the LDH-like compound separator, but this is not particularly limited. In(OH)3 can have a cubic crystalline structure or be composed of In(OH)3 crystals surrounded by an LDH-like compound. In(OH)3 can be identified using X-ray diffraction. X-ray diffraction measurements can preferably be performed in the order given in the examples described later.

[0088] As described above, the LDH-like compound separator comprises an LDH-like compound and a porous substrate (typically composed of a porous substrate and an LDH-like compound), and the LDH-like compound seals the pores of the porous substrate, thereby enabling the LDH-like compound separator to exhibit hydroxide ion conductivity and air impermeability (thus functioning as an LDH-like compound separator exhibiting hydroxide ion conductivity). It is particularly preferred that the LDH-like compound is embedded throughout the thickness direction of the porous substrate made of polymer material. The thickness of the LDH-like compound separator is preferably 5–80 μm, more preferably 5–60 μm, and even more preferably 5–40 μm.

[0089] The porous substrate is made of polymeric materials. Polymer porous substrates have the following advantages: 1) flexibility (therefore, even with thinning, cracking is difficult); 2) easy improvement of porosity; 3) easy improvement of conductivity (due to the ability to improve porosity and reduce thickness); 4) ease of manufacturing and processing. Furthermore, by flexibly utilizing the flexibility derived from 1), the following advantage is also provided: 5) it is possible to easily bend or seal LDH-like compound separators comprising porous substrates made of polymeric materials. Preferred examples of polymeric materials include: polystyrene, polyethersulfone, polypropylene, epoxy resin, polyphenylene sulfide, fluoropolymers (tetrafluoroethylene resins: PTFE, etc.), cellulose, nylon, polyethylene, and any combination thereof. More preferably, based on the viewpoint of thermoplastic resins suitable for heat pressing, examples include: polystyrene, polyethersulfone, polypropylene, epoxy resin, polyphenylene sulfide, fluoropolymers (tetrafluoroethylene resins: PTFE, etc.), nylon, polyethylene, and any combination thereof. All of the aforementioned preferred materials possess alkali resistance, making them suitable for use as electrolytes in batteries. From the viewpoint of excellent resistance to hot water, acids, and alkalis, and low cost, polyolefins such as polypropylene and polyethylene are particularly preferred polymeric materials, with polypropylene or polyethylene being the most preferred. When the porous substrate is composed of a polymeric material, it is particularly preferable that the LDH-like compound layer is embedded throughout the entire thickness direction of the porous substrate (e.g., most or almost all of the pores inside the porous substrate are filled with the LDH-like compound). Commercially available polymeric microporous membranes can be preferably used as such polymeric porous substrates.

[0090] Manufacturing method

[0091] There is no particular limitation on the manufacturing method of LDH-like compound separators. They can be manufactured by appropriately modifying the conditions (especially the composition of LDH raw materials) of known manufacturing methods of LDH-containing functional layers and composite materials (see, for example, Patent Documents 1-4). For example, (1) a porous substrate is prepared; (2) a solution containing titanium dioxide sol (or, also containing yttrium sol and / or alumina sol) is coated onto the porous substrate and dried to form a titanium dioxide layer; (3) the porous substrate is impregnated with a solution containing magnesium ions (Mg... 2+ ) and urea (or, also contains yttrium ions (Y) 3+ (3) In the raw material aqueous solution; (4) The porous substrate is subjected to hydrothermal treatment in the raw material aqueous solution, so that the functional layer containing LDH-like compounds is formed on and / or in the porous substrate, thereby enabling the manufacture of the functional layer containing LDH-like compounds and composite material (i.e., LDH-like compound separator). In addition, it is believed that: because urea is present in the above process (3), ammonia is generated in the solution by the hydrolysis of urea, thereby increasing the pH value, and the coexisting metal ions form hydroxides and / or oxides, thereby obtaining LDH-like compounds.

[0092] Especially in the case of manufacturing a composite material with a porous substrate made of polymeric material and an LDH-like compound embedded in the entire thickness direction of the porous substrate (i.e., an LDH-like compound partition), it is preferable to apply the mixed sol solution to the substrate in step (2) by a method that allows the mixed sol solution to penetrate into the entire or most of the interior of the substrate. This allows most or almost all of the pores inside the porous substrate to be filled with the LDH-like compound. Examples of preferred coating methods include dip coating and filter coating, with dip coating being particularly preferred. The amount of mixed sol solution adhering can be adjusted by changing the number of coats applied in dip coating or similar methods. After the substrate coated with the mixed sol solution by dip coating or similar methods is dried, steps (3) and (4) above can be performed.

[0093] When the porous substrate is made of a polymer material, it is preferable to perform a pressing process on the LDH-like compound separator obtained by the above-described method. This results in an LDH-like compound separator with superior density. The pressing method can be, for example, roll pressing, uniaxial pressing, CIP (cold isostatic pressing), etc., without particular limitation, but roll pressing is preferred. By softening the porous polymer substrate, the pores of the porous substrate can be fully sealed using the LDH-like compound; in this regard, it is preferable to perform the pressing while heating. For example, in the case of polypropylene and polyethylene, heating at 60–200°C is preferred as the temperature for sufficient softening. By performing pressing such as roll pressing within this temperature range, the residual pores in the LDH-like compound separator can be significantly reduced. As a result, the LDH-like compound separator can be made extremely dense, thus further effectively suppressing short circuits caused by zinc dendrites. During roll pressing, by appropriately adjusting the roll gap and roll temperature, the morphology of the residual pores can be controlled, thereby obtaining an LDH-like compound separator with the desired density.

[0094] Example

[0095] The following examples provide a more specific illustration of the LDH-like compound separator that can be used in this invention.

[0096] [Examples A1~A8]

[0097] Examples A1 to A7 given below are reference examples related to LDH-like compound separators, while example A8 is a comparative example related to LDH separators. LDH-like compound separators and LDH separators are collectively referred to as hydroxide ion-conducting separators. It should be noted that the evaluation method for the hydroxide ion-conducting separators fabricated in the following examples is as follows.

[0098] Rating 1 Observation of surface microstructure

[0099] The surface microstructure of the hydroxide ion-conducting septum was observed using a scanning electron microscope (SEM, JSM-6610LV, manufactured by JEOL) at an accelerating voltage of 10–20 kV.

[0100] Rating 2 STEM analysis of layered structures

[0101] The layered structure of the hydroxide ion-conducting septum was observed using a scanning transmission electron microscope (STEM) (product name: JEM-ARM200F, manufactured by JEOL) at an accelerating voltage of 200 kV.

[0102] Rating 3 Elemental Analysis and Evaluation (EDS)

[0103] The surface composition of the hydroxide ion-conducting separator was analyzed using an EDS analyzer (X-act, Oxford Instruments) to calculate the atomic ratio of Mg:Ti:Y:Al. The analysis was performed as follows: 1) Images were acquired at an accelerating voltage of 20 kV and a magnification of 5,000x; 2) Three-point analysis was performed in point analysis mode with approximately 5 μm intervals; 3) Steps 1) and 2) were repeated once more; 4) The average value of the six points was calculated.

[0104] Rating 4 X-ray diffraction measurement

[0105] The crystalline phase of the hydroxide ion-conducting septum was determined using an X-ray diffractometer (RINT TTR III, Rigaku Corporation) under the following conditions: voltage: 50 kV, current: 300 mA, and measurement range: 5–40°. The resulting XRD pattern was obtained. Furthermore, the interlayer distance of the layered crystalline structure was determined using the 2θ peak corresponding to the peak derived from LDH-like compounds, according to the Bragg formula.

[0106] Rating 5 He measured

[0107] To evaluate the compactness of the hydroxide ion-conducting separator from the perspective of He permeability, a He permeability test was conducted as follows. First, a... Figure 6A and Figure 6B The He transmittance measuring system 310 is shown. The He transmittance measuring system 310 is configured such that He gas from a gas cylinder filled with He gas is supplied to a sample holder 316 via a pressure gauge 312 and a flow meter 314 (digital flow meter), and is discharged from one side of a hydroxide ion conduction partition 318 held on the sample holder 316 to the other side.

[0108] The sample holder 316 has a structure including a gas supply port 316a, a sealed space 316b, and a gas outlet 316c, and is assembled as follows. First, an adhesive 322 is applied along the outer periphery of the hydroxide ion conducting separator 318, and it is mounted on a clamp 324 (made of ABS resin) with a central opening. Butyl rubber seals are provided at the upper and lower ends of the clamp 324 as sealing members 326a and 326b. Then, support members 328a and 328b (made of PTFE) with openings formed by flanges are used to clamp the sample holder from the outside of the sealing members 326a and 326b. In this way, the sealed space 316b is divided by the hydroxide ion conducting separator 318, the clamp 324, the sealing member 326a, and the support member 328a. The support members 328a and 328b are fastened to each other by using a screw fastening mechanism 330, so that He gas will not leak from any part other than the gas outlet 316c. The gas supply port 316a of the sample holder 316 assembled in this way is connected to a gas supply pipe 334 by means of a connector 332.

[0109] Next, He gas is supplied to the He transmittance measuring system 310 via gas supply pipe 334, allowing it to pass through the hydroxide ion conduction partition 318 held within the sample holder 316. During this time, the gas supply pressure and flow rate are monitored using pressure gauge 312 and flow meter 314. After He gas permeation for 1–30 minutes, the He transmittance is calculated. The He transmittance is calculated using the He gas permeation rate F (cm³) per unit time. 3 The parameters are: (r / min), the differential pressure P (atm) applied to the hydroxide ion-conducting separator during He gas permeation, and the membrane area S (cm²) during He gas permeation. 2 The permeation rate of He gas, F (cm³), is calculated using the formula F / (P×S). 3 The flow rate ( / min) is read directly from flow meter 314. Additionally, the differential pressure P is measured using gauge pressure from pressure gauge 312. It should be noted that He gas is supplied with a differential pressure P ranging from 0.05 to 0.90 atm.

[0110] Rating 6 Determination of ionic conductivity

[0111] use Figure 7The electrochemical measurement system shown is used to determine the conductivity of the hydroxide ion-conducting separator in the electrolyte as follows. The hydroxide ion-conducting separator sample S is clamped from both sides by silicone sealants 440 with a thickness of 1 mm and installed in a PTFE flanged electrolytic cell 442 with an inner diameter of 6 mm. As electrodes 446, a #100 mesh nickel mesh is installed in the electrolytic cell 442 in a cylindrical shape with a diameter of 6 mm, with a distance of 2.2 mm between electrodes. As the electrolyte 444, a 5.4 M KOH aqueous solution is filled into the electrolytic cell 442. The measurement is performed using an electrochemical measurement system (constant voltage / constant current-frequency response analyzer, Solartron 1287A and 1255B models) under conditions of a frequency range of 1 MHz to 0.1 Hz and an applied voltage of 10 mV. The intercept of the real number axis is taken as the resistance of the hydroxide ion-conducting separator sample S. The same measurement is performed with a sample S without a hydroxide ion-conducting separator to determine the blank resistance. The difference between the resistance of the hydroxide ion-conducting separator sample S and the blank resistance is taken as the resistance of the hydroxide ion-conducting separator. The conductivity is then calculated using the resistance, thickness, and area of ​​the obtained hydroxide ion-conducting separator.

[0112] Rating 7 Alkali resistance evaluation

[0113] Prepare a 5.4M KOH aqueous solution containing zinc oxide at a concentration of 0.4M. Place 0.5 mL of the prepared KOH aqueous solution and a 2 cm square hydroxide ion-conducting separator sample into a sealed Teflon (registered trademark) container. Then, after maintaining the temperature at 90°C for 1 week (168 hours), remove the hydroxide ion-conducting separator sample from the sealed container. Dry the removed hydroxide ion-conducting separator sample at room temperature overnight. For the obtained sample, calculate the He transmittance using the same method as in Evaluation 5 to determine whether there is a change in He transmittance before and after alkali impregnation.

[0114] Rating 8 Evaluation of dendrite tolerance (cyclic testing)

[0115] To evaluate the effectiveness of the hydroxide ion-conducting separator in suppressing short circuits caused by zinc dendrites (dendrite tolerance), a cyclic test was conducted as follows. First, the positive electrode (containing nickel hydroxide and / or nickel hydroxide) and the negative electrode (containing zinc and / or zinc oxide) were each wrapped with non-woven fabric, and current extraction terminals were welded onto them. The prepared positive and negative electrodes were then placed opposite each other, separated by the hydroxide ion-conducting separator, and sandwiched between a laminated film with current extraction ports. Three sides of the laminated film were heat-sealed. An electrolyte (a liquid obtained by dissolving 0.4 M zinc oxide in a 5.4 M KOH aqueous solution) was added to the resulting open-top single-cell container. The electrolyte was then fully permeated into the positive and negative electrodes using methods such as vacuuming. Finally, the remaining side of the laminated film was also heat-sealed to create a simple, sealed single-cell battery. Using a charge-discharge apparatus (TOSCAT3100 manufactured by Toyo Systems, Ltd.), formation was performed on a simple, sealed single-cell battery at 0.1C charge and 0.2C discharge. Then, a 1C charge-discharge cycle was performed. While repeatedly performing charge-discharge cycles under the same conditions, the voltage between the positive and negative terminals was monitored using a voltmeter. The presence of a sharp voltage drop (specifically, a voltage drop of 5mV or more relative to the previously plotted voltage) caused by a short circuit between the positive and negative terminals was investigated, and the evaluation was performed according to the following criteria.

[0116] • No short circuit: No sharp voltage drop was observed during charging after 300 cycles.

[0117] • Short circuit: The sharp voltage drop mentioned above will be seen during charging if the number of cycles is less than 300.

[0118] Example A1 (refer to)

[0119] (1) Preparation of porous polymer substrate

[0120] A commercially available polyethylene microporous membrane with a porosity of 50%, an average pore diameter of 0.1 μm, and a thickness of 20 μm was prepared as a polymer porous substrate and cut into 2.0 cm × 2.0 cm pieces.

[0121] (2) Coating titanium dioxide sol onto a porous polymer substrate

[0122] Titanium oxide sol solution (M6, manufactured by Tagi Chemical Co., Ltd.) was applied to the substrate prepared in (1) above by dip coating. The dip coating was performed as follows: the substrate was immersed in 100 ml of sol solution, then lifted vertically and dried at room temperature for 3 hours.

[0123] (3) Preparation of raw material aqueous solution

[0124] Magnesium nitrate hexahydrate (Mg(NO3)2·6H2O, manufactured by Kanto Chemical Co., Ltd.) and urea ((NH2)2CO, manufactured by Sigma Aldrich) were prepared as raw materials. Magnesium nitrate hexahydrate was weighed at a concentration of 0.015 mol / L and placed in a beaker. Ion-exchanged water was added to bring the total volume to 75 ml. After stirring the resulting solution, urea / NO3 was added... － Urea, weighed at a ratio of 48 (molar ratio), is added to the solution, and further stirring is performed to obtain a raw material aqueous solution.

[0125] (4) Film formation based on hydrothermal treatment

[0126] The raw material aqueous solution and the impregnated substrate are sealed together in a Teflon (registered trademark) sealed container (autoclave container, internal volume 100ml, outer sleeve made of stainless steel). The substrate is then floated from the bottom of the Teflon (registered trademark) sealed container and fixed in a vertical position so that the solution is in contact with both sides of the substrate. A hydrothermal treatment is then performed at 120°C for 24 hours, thereby forming an LDH-like compound on the surface and inside the substrate. After a specified time, the substrate is removed from the sealed container, washed with deionized water, and dried at 70°C for 10 hours, thereby forming an LDH-like compound within the pores of the porous substrate. This yields an LDH-like compound separator.

[0127] (5) Densification based on roll pressing

[0128] The LDH-like compound separator described above was clamped using a pair of PET films (Lumirror manufactured by Toray Corporation, registered trademark, 40 μm thick) and rolled at a roller rotation speed of 3 mm / s, a roller heating temperature of 70°C, and a roller gap of 70 μm to obtain a further densified LDH-like compound separator.

[0129] (6) Evaluation Results

[0130] The obtained LDH-like compound separators were evaluated 1–8. The results are as follows.

[0131] - Evaluation 1: SEM image of the surface microstructure of the LDH-like compound separator (before rolling) obtained in Example A1 is as follows: Figure 8A As shown.

[0132] - Evaluation 2: Based on the results that the layered lattice stripes can be identified, it is confirmed that the LDH-like compound separator, except for the porous substrate, is a compound with a layered crystalline structure.

[0133] - Evaluation 3: As a result of EDS elemental analysis, Mg and Ti, which are constituent elements of the LDH-like compound, were detected on the surface of the LDH-like compound separator. Furthermore, the atomic ratios of Mg and Ti on the surface of the LDH-like compound separator, calculated by EDS elemental analysis, are shown in Table 1.

[0134] - Rating 4: Figure 8B The XRD pattern obtained in Example A1 is shown. A peak was observed near 2θ = 9.4° in the obtained XRD pattern. Typically, the (003) peak of LDH is observed at 2θ = 11–12°; therefore, it is assumed that the above peak is a shift of the (003) peak of LDH to a lower angle. This suggests that the above peak originates from a compound that, while not technically LDH, is similar to LDH (i.e., an LDH-like compound). It should be noted that the two peaks observed at 20 < 2θ° < 25° in the XRD pattern originate from the polyethylene constituting the porous substrate. Furthermore, the interlayer distance of the layered crystalline structure in the LDH-like compound is 0.94 nm.

[0135] - Evaluation 5: As shown in Table 1, the extremely high density of He with a transmittance of 0.0 cm / min·atm was confirmed.

[0136] - Evaluation 6: As shown in Table 1, high ionic conductivity was confirmed.

[0137] - Evaluation 7: The He transmission rate after alkali impregnation was 0.0 cm / min·atm, the same as in Evaluation 5, confirming the excellent alkali resistance that the He transmission rate did not change even after alkali impregnation at a high temperature of up to 90°C for 1 week.

[0138] - Evaluation 8: As shown in Table 1, excellent dendrite tolerance was confirmed, with no short circuits caused by zinc dendrites even after 300 cycles.

[0139] Example A2 (refer to)

[0140] Except for preparing the raw material aqueous solution as described in (3) and setting the temperature of the hydrothermal treatment in (4) to 90°C, the LDH-like compound separator was prepared and evaluated in the same manner as in Example A1.

[0141] (Preparation of raw material aqueous solution)

[0142] Magnesium nitrate hexahydrate (Mg(NO3)2·6H2O, manufactured by Kanto Chemical Co., Ltd.) and urea ((NH2)2CO, manufactured by Sigma Aldrich) were prepared as raw materials. Magnesium nitrate hexahydrate was weighed at a concentration of 0.03 mol / L and placed in a beaker. Ion-exchanged water was added to bring the total volume to 75 ml. After stirring the resulting solution, urea / NO3 was added... － Urea, weighed in a ratio of 8 (molar ratio), is added to the solution and further stirred to obtain a raw material aqueous solution.

[0143] - Evaluation 1: SEM image of the surface microstructure of the LDH-like compound separator (before rolling) obtained in Example A2 is as follows: Figure 9A As shown.

[0144] - Evaluation 2: Based on the results that the layered lattice stripes can be identified, it is confirmed that the LDH-like compound separator, except for the porous substrate, is a compound with a layered crystalline structure.

[0145] - Evaluation 3: As a result of EDS elemental analysis, Mg and Ti, which are constituent elements of the LDH-like compound, were detected on the surface of the LDH-like compound separator. Furthermore, the atomic ratios of Mg and Ti on the surface of the LDH-like compound separator, calculated by EDS elemental analysis, are shown in Table 1.

[0146] - Rating 4: Figure 9B The XRD pattern obtained in Example A2 is shown. A peak was observed near 2θ = 7.2° in the obtained XRD pattern. Typically, the (003) peak of LDH is observed at 2θ = 11–12°; therefore, it is assumed that the above peak is a shift of the (003) peak of LDH to a lower angle. This suggests that the above peak originates from a compound that, while not officially called LDH, is similar to LDH (i.e., an LDH-like compound). It should be noted that the two peaks observed at 20 < 2θ° < 25° in the XRD pattern originate from polyethylene, which constitutes the porous substrate. Furthermore, the interlayer distance of the layered crystalline structure in the LDH-like compound is 1.2 nm.

[0147] - Evaluation 5: As shown in Table 1, the extremely high density of He with a transmittance of 0.0 cm / min·atm was confirmed.

[0148] - Evaluation 6: As shown in Table 1, high ionic conductivity was confirmed.

[0149] - Evaluation 7: The He transmission rate after alkali impregnation was 0.0 cm / min·atm, the same as in Evaluation 5, confirming the excellent alkali resistance that the He transmission rate did not change even after alkali impregnation at a high temperature of up to 90°C for 1 week.

[0150] - Evaluation 8: As shown in Table 1, excellent dendrite tolerance was confirmed, with no short circuits caused by zinc dendrites even after 300 cycles.

[0151] Example A3 (refer to)

[0152] In addition to replacing (2) above by coating a porous polymer substrate with titanium dioxide-yttrium oxide sol as described below, the LDH-like compound separator was fabricated and evaluated in the same manner as in Example A1.

[0153] (Coating titanium dioxide-yttrium oxide sol onto a porous polymer substrate)

[0154] Titanium oxide sol solution (M6, manufactured by Tagi Chemical Co., Ltd.) and yttrium sol were mixed at a Ti / Y (molar ratio) of 4. The mixed solution was then applied to the substrate prepared in (1) above by dip coating. The dip coating was performed by immersing the substrate in 100 ml of the mixed solution, then lifting it vertically and drying it at room temperature for 3 hours.

[0155] - Evaluation 1: SEM image of the surface microstructure of the LDH-like compound separator (before rolling) obtained in Example A3 is as follows: Figure 10A As shown.

[0156] - Evaluation 2: Based on the results that the layered lattice stripes can be identified, it is confirmed that the LDH-like compound separator, except for the porous substrate, is a compound with a layered crystalline structure.

[0157] - Evaluation 3: As a result of EDS elemental analysis, Mg, Ti, and Y, which are constituent elements of the LDH-like compound, were detected on the surface of the LDH-like compound separator. Furthermore, the atomic ratios of Mg, Ti, and Y on the surface of the LDH-like compound separator calculated by EDS elemental analysis are shown in Table 1.

[0158] - Rating 4: Figure 10B The XRD pattern obtained in Example A3 is shown. In the obtained XRD pattern, a peak was observed near 2θ = 8.0°. Typically, the (003) peak of LDH is observed at 2θ = 11–12°; therefore, it is assumed that the above peak is obtained by shifting the (003) peak of LDH to a lower angle. This suggests that the above peak originates from a compound that, while not technically LDH, is similar to LDH (i.e., an LDH-like compound). It should be noted that the two peaks observed at 20 < 2θ° < 25° in the XRD pattern originate from the polyethylene constituting the porous substrate. Furthermore, the interlayer distance of the layered crystalline structure in the LDH-like compound is 1.1 nm.

[0159] - Evaluation 5: As shown in Table 1, the extremely high density of He with a transmittance of 0.0 cm / min·atm was confirmed.

[0160] - Evaluation 6: As shown in Table 1, high ionic conductivity was confirmed.

[0161] - Evaluation 7: The He transmission rate after alkali impregnation was 0.0 cm / min·atm, the same as in Evaluation 5, confirming the excellent alkali resistance that the He transmission rate did not change even after alkali impregnation at a high temperature of up to 90°C for 1 week.

[0162] - Evaluation 8: As shown in Table 1, excellent dendrite tolerance was confirmed, with no short circuits caused by zinc dendrites even after 300 cycles.

[0163] Example A4 (refer to)

[0164] In addition to replacing (2) above by coating a porous polymer substrate with titanium dioxide, yttrium oxide and alumina sol as described below, the LDH-like compound separator was fabricated and evaluated in the same manner as in Example A1.

[0165] (Coating titanium dioxide-yttrium oxide-alumina sol onto a porous polymer substrate)

[0166] Titanium oxide sol solution (M6, manufactured by Tagi Chemical Co., Ltd.), yttrium sol, and amorphous alumina solution (Al-ML15, manufactured by Tagi Chemical Co., Ltd.) were mixed at a molar ratio of Ti / (Y+Al) = 2 and a molar ratio of Y / Al = 8. The mixed solution was applied to the substrate prepared in (1) above by dip coating. The dip coating was performed by immersing the substrate in 100 ml of the mixed solution, then lifting it vertically and drying it at room temperature for 3 hours.

[0167] - Evaluation 1: SEM image of the surface microstructure of the LDH-like compound separator (before rolling) obtained in Example A4 is as follows: Figure 11A As shown.

[0168] - Evaluation 2: Based on the results that the layered lattice stripes can be identified, it is confirmed that the LDH-like compound separator, except for the porous substrate, is a compound with a layered crystalline structure.

[0169] - Evaluation 3: As a result of EDS elemental analysis, Mg, Al, Ti, and Y, which are constituent elements of the LDH-like compound, were detected on the surface of the LDH-like compound separator. Furthermore, the atomic ratios of Mg, Al, Ti, and Y on the surface of the LDH-like compound separator, calculated by EDS elemental analysis, are shown in Table 1.

[0170] - Rating 4: Figure 11B The XRD pattern obtained in Example A4 is shown. A peak was observed near 2θ = 7.8° in the obtained XRD pattern. Typically, the (003) peak of LDH is observed at 2θ = 11–12°; therefore, it is assumed that the above peak is a shift of the (003) peak of LDH to a lower angle. This suggests that the above peak originates from a compound that, while not officially called LDH, is similar to LDH (i.e., an LDH-like compound). It should be noted that the two peaks observed at 20 < 2θ° < 25° in the XRD pattern originate from the polyethylene constituting the porous substrate. Furthermore, the interlayer distance of the layered crystalline structure in the LDH-like compound is 1.1 nm.

[0171] - Evaluation 5: As shown in Table 1, the extremely high density of He with a transmittance of 0.0 cm / min·atm was confirmed.

[0172] - Evaluation 6: As shown in Table 1, high ionic conductivity was confirmed.

[0173] - Evaluation 7: The He transmission rate after alkali impregnation was 0.0 cm / min·atm, the same as in Evaluation 5, confirming the excellent alkali resistance that the He transmission rate did not change even after alkali impregnation at a high temperature of up to 90°C for 1 week.

[0174] - Evaluation 8: As shown in Table 1, excellent dendrite tolerance was confirmed, with no short circuits caused by zinc dendrites even after 300 cycles.

[0175] Example A5 (refer to)

[0176] In addition to coating a porous polymer substrate with titanium dioxide-yttrium oxide sol instead of (2) and preparing the raw material aqueous solution as described in (3), the LDH-like compound separator was prepared and evaluated in the same manner as in Example A1.

[0177] (Coating titanium dioxide-yttrium oxide sol onto a porous polymer substrate)

[0178] Titanium oxide sol solution (M6, manufactured by Tagi Chemical Co., Ltd.) and yttrium sol were mixed at a Ti / Y (molar ratio) of 18. The mixed solution was then applied to the substrate prepared in (1) above by dip coating. The dip coating was performed by immersing the substrate in 100 ml of the mixed solution, then lifting it vertically and drying it at room temperature for 3 hours.

[0179] (Preparation of raw material aqueous solution)

[0180] Magnesium nitrate hexahydrate (Mg(NO3)2·6H2O, manufactured by Kanto Chemical Co., Ltd.) and urea ((NH2)2CO, manufactured by Sigma Aldrich) were prepared as raw materials. Magnesium nitrate hexahydrate was weighed at a concentration of 0.0075 mol / L and placed in a beaker. Ion-exchanged water was added to bring the total volume to 75 ml, and the resulting solution was stirred. The solution was then mixed with urea / NO3... － Urea, weighed at a ratio of 96 (molar ratio), is added to the solution, and further stirring is performed to obtain a raw material aqueous solution.

[0181] - Evaluation 1: SEM image of the surface microstructure of the LDH-like compound separator (before rolling) obtained in Example A5 is as follows: Figure 12A As shown.

[0182] - Evaluation 2: Based on the results that the layered lattice stripes can be identified, it is confirmed that the LDH-like compound separator, except for the porous substrate, is a compound with a layered crystalline structure.

[0183] - Evaluation 3: As a result of EDS elemental analysis, Mg, Ti, and Y, which are constituent elements of the LDH-like compound, were detected on the surface of the LDH-like compound separator. Furthermore, the atomic ratios of Mg, Ti, and Y on the surface of the LDH-like compound separator calculated by EDS elemental analysis are shown in Table 1.

[0184] - Rating 4: Figure 12B The XRD pattern obtained in Example A5 is shown. In the obtained XRD pattern, a peak was observed near 2θ = 8.9°. Typically, the (003) peak of LDH is observed at 2θ = 11–12°; therefore, it is assumed that the above peak is a shift of the (003) peak of LDH to a lower angle. This suggests that the above peak originates from a compound that, while not technically LDH, is similar to LDH (i.e., an LDH-like compound). It should be noted that the two peaks observed at 20 < 2θ° < 25° in the XRD pattern originate from the polyethylene constituting the porous substrate. Furthermore, the interlayer distance of the layered crystalline structure in the LDH-like compound is 0.99 nm.

[0185] - Evaluation 5: As shown in Table 1, the extremely high density of He with a transmittance of 0.0 cm / min·atm was confirmed.

[0186] - Evaluation 6: As shown in Table 1, high ionic conductivity was confirmed.

[0187] - Evaluation 7: The He transmission rate after alkali impregnation was 0.0 cm / min·atm, the same as in Evaluation 5, confirming the excellent alkali resistance that the He transmission rate did not change even after alkali impregnation at a high temperature of up to 90°C for 1 week.

[0188] - Evaluation 8: As shown in Table 1, excellent dendrite tolerance was confirmed, with no short circuits caused by zinc dendrites even after 300 cycles.

[0189] Example A6 (refer to)

[0190] In addition to coating a porous polymer substrate with titanium dioxide-alumina sol instead of (2) and preparing the raw material aqueous solution as described in (3), the LDH-like compound separator was prepared and evaluated in the same manner as in Example A1.

[0191] (Coating titanium dioxide-alumina sol onto a porous polymer substrate)

[0192] Titanium oxide sol solution (M6, manufactured by Tamaki Chemical Co., Ltd.) and amorphous alumina solution (Al-ML15, manufactured by Tamaki Chemical Co., Ltd.) were mixed at a Ti / Al (molar ratio) of 18. The mixed solution was then applied to the substrate prepared in (1) above by dip coating. The dip coating was performed by immersing the substrate in 100 ml of the mixed solution, then lifting it vertically and drying it at room temperature for 3 hours.

[0193] (Preparation of raw material aqueous solution)

[0194] Magnesium nitrate hexahydrate (Mg(NO3)2·6H2O, manufactured by Kanto Chemical Co., Ltd.), yttrium nitrate n hydrate (Y(NO3)3·nH2O, manufactured by Fuji Thin Film & Television Co., Ltd.), and urea ((NH2)2CO, manufactured by Sigma-Aldrich) were prepared as raw materials. Magnesium nitrate hexahydrate was weighed at 0.0015 mol / L and placed into a beaker. Then, yttrium nitrate n hydrate was weighed at 0.0075 mol / L and placed into the same beaker. Ion-exchanged water was added to bring the total volume to 75 ml, and the resulting solution was stirred. The solution was then mixed with urea / NO3... － Urea weighed in a ratio of 9.8 (molar ratio) is added to the solution, and further stirring is carried out to obtain a raw material aqueous solution.

[0195] - Evaluation 1: SEM image of the surface microstructure of the LDH-like compound separator (before rolling) obtained in Example A6 is as follows: Figure 13A As shown.

[0196] - Evaluation 2: Based on the results that the layered lattice stripes can be identified, it is confirmed that the LDH-like compound separator, except for the porous substrate, is a compound with a layered crystalline structure.

[0197] - Evaluation 3: As a result of EDS elemental analysis, Mg, Al, Ti, and Y, which are constituent elements of the LDH-like compound, were detected on the surface of the LDH-like compound separator. Furthermore, the atomic ratios of Mg, Al, Ti, and Y on the surface of the LDH-like compound separator, calculated by EDS elemental analysis, are shown in Table 1.

[0198] - Rating 4: Figure 13B The XRD pattern obtained in Example A6 is shown. A peak was observed near 2θ = 7.2° in the obtained XRD pattern. Typically, the (003) peak of LDH is observed at 2θ = 11–12°; therefore, it is assumed that the above peak is a shift of the (003) peak of LDH to a lower angle. This suggests that the above peak originates from a compound that, while not technically LDH, is similar to LDH (i.e., an LDH-like compound). It should be noted that the two peaks observed at 20 < 2θ° < 25° in the XRD pattern originate from the polyethylene constituting the porous substrate. Furthermore, the interlayer distance of the layered crystalline structure in the LDH-like compound is 1.2 nm.

[0199] - Evaluation 5: As shown in Table 1, the extremely high density of He with a transmittance of 0.0 cm / min·atm was confirmed.

[0200] - Evaluation 6: As shown in Table 1, high ionic conductivity was confirmed.

[0201] - Evaluation 7: The He transmission rate after alkali impregnation was 0.0 cm / min·atm, the same as in Evaluation 5, confirming the excellent alkali resistance that the He transmission rate did not change even after alkali impregnation at a high temperature of up to 90°C for 1 week.

[0202] - Evaluation 8: As shown in Table 1, excellent dendrite tolerance was confirmed, with no short circuits caused by zinc dendrites even after 300 cycles.

[0203] Example A7 (refer to)

[0204] In addition to preparing the raw material aqueous solution as described in (3) above, the LDH-like compound separator was prepared and evaluated in the same manner as in Example A6.

[0205] (Preparation of raw material aqueous solution)

[0206] Magnesium nitrate hexahydrate (Mg(NO3)2·6H2O, manufactured by Kanto Chemical Co., Ltd.), yttrium nitrate n hydrate (Y(NO3)3·nH2O, manufactured by Fuji Thin Film & Television Co., Ltd.), and urea ((NH2)2CO, manufactured by Sigma-Aldrich) were prepared as raw materials. Magnesium nitrate hexahydrate was weighed at 0.0075 mol / L and placed into a beaker. Then, yttrium nitrate n hydrate was weighed at 0.0075 mol / L and placed into the same beaker. Ion-exchanged water was added to bring the total volume to 75 ml, and the resulting solution was stirred. The solution was then mixed with urea / NO3... － Urea, weighed in a ratio of 25.6 (molar ratio), is added to the solution and further stirred to obtain an aqueous solution of the raw material.

[0207] - Evaluation 1: SEM image of the surface microstructure of the LDH-like compound separator (before rolling) obtained in Example A7 is as follows: Figure 14 As shown.

[0208] - Evaluation 2: Based on the results that the layered lattice stripes can be identified, it is confirmed that the LDH-like compound separator, except for the porous substrate, is a compound with a layered crystalline structure.

[0209] - Evaluation 3: As a result of EDS elemental analysis, Mg, Al, Ti, and Y, which are constituent elements of the LDH-like compound, were detected on the surface of the LDH-like compound separator. Furthermore, the atomic ratios of Mg, Al, Ti, and Y on the surface of the LDH-like compound separator, calculated by EDS elemental analysis, are shown in Table 1.

[0210] - Evaluation 5: As shown in Table 1, the extremely high density of He with a transmittance of 0.0 cm / min·atm was confirmed.

[0211] - Evaluation 6: As shown in Table 1, high ionic conductivity was confirmed.

[0212] - Evaluation 7: The He transmission rate after alkali impregnation was 0.0 cm / min·atm, the same as in Evaluation 5, confirming the excellent alkali resistance that the He transmission rate did not change even after alkali impregnation at a high temperature of up to 90°C for 1 week.

[0213] - Evaluation 8: As shown in Table 1, excellent dendrite tolerance was confirmed, with no short circuits caused by zinc dendrites even after 300 cycles.

[0214] Example A8 (Compare)

[0215] Except for the following method of coating alumina sol instead of (2) above, the LDH partition is fabricated and evaluated in the same manner as in Example A1.

[0216] (Coating alumina sol onto a porous polymer substrate)

[0217] Amorphous alumina sol (Al-ML15, manufactured by Tagi Chemical Co., Ltd.) was applied to the substrate prepared in (1) above by dip coating. The dip coating was performed by immersing the substrate in 100 ml of amorphous alumina sol, then lifting it vertically and drying it at room temperature for 3 hours.

[0218] - Evaluation 1: The SEM image of the surface microstructure of the LDH partition (before rolling) obtained in Example A8 is as follows: Figure 15A As shown.

[0219] - Evaluation 2: Based on the results that the layered lattice stripes can be identified, it is confirmed that the part of the LDH separator, excluding the porous substrate, is a compound with a layered crystalline structure.

[0220] - Evaluation 3: As a result of EDS elemental analysis, Mg and Al, which are constituent elements of LDH, were detected on the surface of the LDH separator. Furthermore, the atomic ratios of Mg and Al on the LDH separator surface calculated by EDS elemental analysis are shown in Table 1.

[0221] - Rating 4: Figure 15B The XRD pattern obtained in Example A8 is shown. Based on the peak near 2θ = 11.5° in the obtained XRD pattern, the LDH separator obtained in Example A8 was identified as LDH (hydrotalcite compound). This identification was performed using the diffraction peaks of LDH (hydrotalcite compound) described in JCPDS Card NO. 35-0964. It should be noted that the two peaks observed at 20 < 2θ° < 25° in the XRD pattern originate from the polyethylene constituting the porous substrate.

[0222] - Evaluation 5: As shown in Table 1, the extremely high density of He with a transmittance of 0.0 cm / min·atm was confirmed.

[0223] - Evaluation 6: As shown in Table 1, high ionic conductivity was confirmed.

[0224] - Evaluation 7: As a result of alkali impregnation at a high temperature of up to 90°C for 1 week, the He transmittance of 0.0 cm / min·atm in Evaluation 5 exceeded 10 cm / min·atm, indicating a deterioration in alkali resistance.

[0225] - Evaluation 8: As shown in Table 1, a short circuit caused by zinc dendrites occurred at less than 300 cycles, indicating that the dendrite tolerance is poor.

[0226] [Table 1]

[0227]

[0228] [Example B1~B9]

[0229] Examples B1 to B9 given below are reference examples related to LDH-like compound separators. It should be noted that the evaluation method for the LDH-like compound separators prepared in the following examples is the same as that for examples A1 to A8, except that the composition ratio (atomic ratio) of Mg:Al:Ti:Y:addition element M calculated in evaluation 3 is used.

[0230] Example B1 (refer to)

[0231] (1) Preparation of porous polymer substrate

[0232] A commercially available polyethylene microporous membrane with a porosity of 50%, an average pore diameter of 0.1 μm, and a thickness of 20 μm was prepared as a polymer porous substrate and cut into 2.0 cm × 2.0 cm pieces.

[0233] (2) Coating a titanium dioxide-yttrium trioxide-alumina sol onto a porous polymer substrate.

[0234] Titanium oxide sol solution (M6, manufactured by Tagi Chemical Co., Ltd.), yttrium sol, and amorphous alumina solution (Al-ML15, manufactured by Tagi Chemical Co., Ltd.) were mixed at a molar ratio of Ti / (Y+Al) = 2 and a molar ratio of Y / Al = 8. The mixed solution was applied to the substrate prepared in (1) above by dip coating. The dip coating was performed by immersing the substrate in 100 ml of the mixed solution, then lifting it vertically and drying it at room temperature for 3 hours.

[0235] (3) Preparation of raw material aqueous solution (I)

[0236] Magnesium nitrate hexahydrate (Mg(NO3)2·6H2O, manufactured by Kanto Chemical Co., Ltd.) and urea ((NH2)2CO, manufactured by Sigma Aldrich) were prepared as raw materials. Magnesium nitrate hexahydrate was weighed at a concentration of 0.015 mol / L and placed in a beaker. Ion-exchanged water was added to bring the total volume to 75 ml. After stirring the resulting solution, urea / NO3 was added... － Urea weighed at a ratio of 48 (molar ratio) is added to the solution, and further stirring is carried out to obtain the raw material aqueous solution (I).

[0237] (4) Film formation based on hydrothermal treatment

[0238] The raw material aqueous solution (I) and the impregnated substrate are sealed together in a Teflon (registered trademark) sealed container (autoclave container, internal volume 100ml, outer sleeve made of stainless steel). The substrate is then floated from the bottom of the Teflon (registered trademark) sealed container and fixed in a vertical position so that the solution is in contact with both sides of the substrate. A hydrothermal treatment is then performed at 120°C for 22 hours, thereby forming an LDH-like compound on the surface and inside the substrate. After the specified time, the substrate is removed from the sealed container, washed with deionized water, and dried at 70°C for 10 hours, thereby forming an LDH-like compound within the pores of the porous substrate.

[0239] (5) Preparation of raw material aqueous solution (II)

[0240] Indium sulfate n-hydrate (In2(SO4)3·nH2O, manufactured by Fuji Thin Film and Kohden Chemical Co., Ltd.) was prepared as a raw material. Indium sulfate n-hydrate was weighed at a concentration of 0.0075 mol / L and placed into a beaker. Ion-exchanged water was added to bring the total volume to 75 ml. The resulting solution was stirred to obtain the raw material aqueous solution (II).

[0241] (6) Indium added based on impregnation treatment

[0242] The raw material aqueous solution (II) and the LDH-like compound separator obtained in (4) above were sealed together in a Teflon (registered trademark) sealed container (autoclave container, internal volume 100 ml, outer sleeve made of stainless steel). At this time, the substrate was floated from the bottom of the Teflon (registered trademark) sealed container and fixed so that the solution was in contact with both sides of the substrate in a vertical position. Then, an immersion treatment was performed at 30°C for 1 hour, thereby adding indium. After a specified time, the substrate was removed from the sealed container, washed with deionized water, and dried at 70°C for 10 hours, thereby obtaining the LDH-like compound separator with added indium.

[0243] (7) Densification based on roll pressing

[0244] The LDH-like compound separator described above was clamped using a pair of PET films (Lumirror manufactured by Toray Corporation, registered trademark, 40 μm thick) and rolled at a roller rotation speed of 3 mm / s, a roller heating temperature of 70°C, and a roller gap of 70 μm to obtain a further densified LDH-like compound separator.

[0245] (8) Evaluation Results

[0246] The obtained LDH-like compound separators were evaluated in various ways. The results are as follows.

[0247] - Evaluation 1: SEM image of the surface microstructure of the LDH-like compound separator (before rolling) obtained in Example B1 is as follows: Figure 16 As shown.

[0248] - Evaluation 2: Based on the results that the layered lattice stripes can be identified, it is confirmed that the LDH-like compound separator, except for the porous substrate, is a compound with a layered crystalline structure.

[0249] - Evaluation 3: As a result of EDS elemental analysis, Al, Ti, Y, and In, which are constituent elements of the LDH-like compound, were detected on the surface of the LDH-like compound separator. Furthermore, the atomic ratios of Al, Ti, Y, and In on the surface of the LDH-like compound separator, calculated by EDS elemental analysis, are shown in Table 2.

[0250] - Evaluation 5: As shown in Table 2, the extremely high density of He with a transmittance of 0.0 cm / min·atm was confirmed.

[0251] - Evaluation 6: As shown in Table 2, high ionic conductivity was confirmed.

[0252] - Evaluation 7: The He transmission rate after alkali impregnation was 0.0 cm / min·atm, the same as in Evaluation 5, confirming the excellent alkali resistance that the He transmission rate did not change even after alkali impregnation at a high temperature of up to 90°C for 1 week.

[0253] - Evaluation 8: As shown in Table 2, excellent dendrite tolerance was confirmed, with no short circuits caused by zinc dendrites even after 300 cycles.

[0254] Example B2 (refer to)

[0255] Except for changing the impregnation time to 24 hours in the impregnation-based indium addition process described in (6) above, the LDH-like compound separator was fabricated and evaluated in the same manner as in Example B1.

[0256] - Evaluation 2: Based on the results that the layered lattice stripes can be identified, it is confirmed that the LDH-like compound separator, except for the porous substrate, is a compound with a layered crystalline structure.

[0257] - Evaluation 3: As a result of EDS elemental analysis, Al, Ti, Y, and In, which are constituent elements of the LDH-like compound, were detected on the surface of the LDH-like compound separator. Furthermore, the atomic ratios of Al, Ti, Y, and In on the surface of the LDH-like compound separator, calculated by EDS elemental analysis, are shown in Table 2.

[0258] - Evaluation 5: As shown in Table 2, the extremely high density of He with a transmittance of 0.0 cm / min·atm was confirmed.

[0259] - Evaluation 6: As shown in Table 2, high ionic conductivity was confirmed.

[0260] - Evaluation 7: The He transmission rate after alkali impregnation was 0.0 cm / min·atm, the same as in Evaluation 5, confirming the excellent alkali resistance that the He transmission rate did not change even after alkali impregnation at a high temperature of up to 90°C for 1 week.

[0261] - Evaluation 8: As shown in Table 2, excellent dendrite tolerance was confirmed, with no short circuits caused by zinc dendrites even after 300 cycles.

[0262] Example B3 (refer to)

[0263] Except for replacing (2) above with coating titanium dioxide-yttrium oxide sol as described below, the LDH-like compound separator was prepared and evaluated in the same manner as in Example B1.

[0264] (Coating titanium dioxide-yttrium oxide sol onto a porous polymer substrate)

[0265] Titanium oxide sol solution (M6, manufactured by Tagi Chemical Co., Ltd.) and yttrium sol were mixed at a Ti / Y (molar ratio) of 2. The mixed solution was then applied to the substrate prepared in (1) above by dip coating. The dip coating was performed by immersing the substrate in 100 ml of the mixed solution, then lifting it vertically and drying it at room temperature for 3 hours.

[0266] - Evaluation 2: Based on the results that the layered lattice stripes can be identified, it is confirmed that the LDH-like compound separator, except for the porous substrate, is a compound with a layered crystalline structure.

[0267] - Evaluation 3: As a result of EDS elemental analysis, Ti, Y, and In, which are constituent elements of the LDH-like compound, were detected on the surface of the LDH-like compound separator. Furthermore, the atomic ratios (composition ratios) of Ti, Y, and In on the surface of the LDH-like compound separator calculated by EDS elemental analysis are shown in Table 2.

[0268] - Evaluation 5: As shown in Table 2, the extremely high density of He with a transmittance of 0.0 cm / min·atm was confirmed.

[0269] - Evaluation 6: As shown in Table 2, high ionic conductivity was confirmed.

[0270] - Evaluation 7: The He transmission rate after alkali impregnation was 0.0 cm / min·atm, the same as in Evaluation 5, confirming the excellent alkali resistance that the He transmission rate did not change even after alkali impregnation at a high temperature of up to 90°C for 1 week.

[0271] - Evaluation 8: As shown in Table 2, excellent dendrite tolerance was confirmed, with no short circuits caused by zinc dendrites even after 300 cycles.

[0272] Example B4 (refer to)

[0273] Except for the preparation of the raw material aqueous solution (II) as described in (5) and the addition of bismuth based on impregnation treatment to replace (6) as described in Example B1, the LDH-like compound separator was prepared and evaluated in the same manner.

[0274] (Preparation of raw material aqueous solution (II))

[0275] Bismuth nitrate pentahydrate (Bi(NO3)3·5H2O) was prepared as a raw material. Bismuth nitrate pentahydrate was weighed at a concentration of 0.00075 mol / L and placed in a beaker. Ion-exchanged water was added to bring the total volume to 75 ml. The resulting solution was stirred to obtain the raw material aqueous solution (II).

[0276] (Bismuth added based on impregnation treatment)

[0277] The raw material aqueous solution (II) and the LDH-like compound separator obtained in (4) above were sealed together in a Teflon (registered trademark) sealed container (autoclave container, internal volume 100 ml, outer sleeve made of stainless steel). At this time, the substrate was floated from the bottom of the Teflon (registered trademark) sealed container and fixed so that the solution was in contact with both sides of the substrate in a vertical position. Then, an impregnation treatment was performed at 30°C for 1 hour, thereby adding bismuth. After the specified time, the substrate was removed from the sealed container, washed with deionized water, and dried at 70°C for 10 hours, thereby obtaining the LDH-like compound separator with added bismuth.

[0278] - Evaluation 2: Based on the results that the layered lattice stripes can be identified, it is confirmed that the LDH-like compound separator, except for the porous substrate, is a compound with a layered crystalline structure.

[0279] - Evaluation 3: As a result of EDS elemental analysis, Mg, Al, Ti, Y, and Bi, which are constituent elements of the LDH-like compound, were detected on the surface of the LDH-like compound separator. Furthermore, the composition ratios (atomic ratios) of Mg, Al, Ti, Y, and Bi on the surface of the LDH-like compound separator calculated by EDS elemental analysis are shown in Table 2.

[0280] - Evaluation 5: As shown in Table 2, the extremely high density of He with a transmittance of 0.0 cm / min·atm was confirmed.

[0281] - Evaluation 6: As shown in Table 2, high ionic conductivity was confirmed.

[0282] - Evaluation 7: The He transmission rate after alkali impregnation was 0.0 cm / min·atm, the same as in Evaluation 5, confirming the excellent alkali resistance that the He transmission rate did not change even after alkali impregnation at a high temperature of up to 90°C for 1 week.

[0283] - Evaluation 8: As shown in Table 2, excellent dendrite tolerance was confirmed, with no short circuits caused by zinc dendrites even after 300 cycles.

[0284] Example B5 (refer to)

[0285] Except for changing the impregnation time to 12 hours in the above-mentioned bismuth-based impregnation process, the LDH-like compound separator was prepared and evaluated in the same manner as in Example B4.

[0286] - Evaluation 2: Based on the results that the layered lattice stripes can be identified, it is confirmed that the LDH-like compound separator, except for the porous substrate, is a compound with a layered crystalline structure.

[0287] - Evaluation 3: As a result of EDS elemental analysis, Mg, Al, Ti, Y, and Bi, which are constituent elements of the LDH-like compound, were detected on the surface of the LDH-like compound separator. Furthermore, the composition ratios (atomic ratios) of Mg, Al, Ti, Y, and Bi on the surface of the LDH-like compound separator calculated by EDS elemental analysis are shown in Table 2.

[0288] - Evaluation 5: As shown in Table 2, the extremely high density of He with a transmittance of 0.0 cm / min·atm was confirmed.

[0289] - Evaluation 6: As shown in Table 2, high ionic conductivity was confirmed.

[0290] - Evaluation 7: The He transmission rate after alkali impregnation was 0.0 cm / min·atm, the same as in Evaluation 5, confirming the excellent alkali resistance that the He transmission rate did not change even after alkali impregnation at a high temperature of up to 90°C for 1 week.

[0291] - Evaluation 8: As shown in Table 2, excellent dendrite tolerance was confirmed, with no short circuits caused by zinc dendrites even after 300 cycles.

[0292] Example B6 (refer to)

[0293] Except for changing the impregnation time to 24 hours in the above-mentioned bismuth-based impregnation process, the LDH-like compound separator was prepared and evaluated in the same manner as in Example B4.

[0294] - Evaluation 2: Based on the results that the layered lattice stripes can be identified, it is confirmed that the LDH-like compound separator, except for the porous substrate, is a compound with a layered crystalline structure.

[0295] - Evaluation 3: As a result of EDS elemental analysis, Mg, Al, Ti, Y, and Bi, which are constituent elements of the LDH-like compound, were detected on the surface of the LDH-like compound separator. Furthermore, the composition ratios (atomic ratios) of Mg, Al, Ti, Y, and Bi on the surface of the LDH-like compound separator calculated by EDS elemental analysis are shown in Table 2.

[0296] - Evaluation 5: As shown in Table 2, the extremely high density of He with a transmittance of 0.0 cm / min·atm was confirmed.

[0297] - Evaluation 6: As shown in Table 2, high ionic conductivity was confirmed.

[0298] - Evaluation 7: The He transmission rate after alkali impregnation was 0.0 cm / min·atm, the same as in Evaluation 5, confirming the excellent alkali resistance that the He transmission rate did not change even after alkali impregnation at a high temperature of up to 90°C for 1 week.

[0299] - Evaluation 8: As shown in Table 2, excellent dendrite tolerance was confirmed, with no short circuits caused by zinc dendrites even after 300 cycles.

[0300] Example B7 (refer to)

[0301] Except for the preparation of the raw material aqueous solution (II) as described in (5) and the addition of calcium based on impregnation treatment to replace (6) as described in (6), the LDH-like compound separator was prepared and evaluated in the same manner as in Example B1.

[0302] (Preparation of raw material aqueous solution (II))

[0303] Calcium nitrate tetrahydrate (Ca(NO3)2·4H2O) was prepared as a raw material. 0.015 mol / L calcium nitrate tetrahydrate was weighed and placed in a beaker, and ion-exchanged water was added to bring the total volume to 75 ml. The resulting solution was stirred to obtain the raw material aqueous solution (II).

[0304] (Calcium added based on impregnation treatment)

[0305] The raw material aqueous solution (II) and the LDH-like compound separator obtained in (4) above were sealed together in a Teflon (registered trademark) sealed container (autoclave container, internal volume 100 ml, outer sleeve made of stainless steel). At this time, the substrate was floated from the bottom of the Teflon (registered trademark) sealed container and fixed so that the solution was in contact with both sides of the substrate in a vertical position. Then, an impregnation treatment was performed at 30°C for 6 hours, thereby adding calcium. After the specified time, the substrate was removed from the sealed container, washed with deionized water, and dried at 70°C for 10 hours, thereby obtaining the LDH-like compound separator with added calcium.

[0306] - Evaluation 2: Based on the results that the layered lattice stripes can be identified, it is confirmed that the LDH-like compound separator, except for the porous substrate, is a compound with a layered crystalline structure.

[0307] - Evaluation 3: As a result of EDS elemental analysis, Mg, Al, Ti, Y, and Ca, which are constituent elements of the LDH-like compound, were detected on the surface of the LDH-like compound separator. Furthermore, the atomic ratios (composition ratios) of Mg, Al, Ti, Y, and Ca on the surface of the LDH-like compound separator, calculated by EDS elemental analysis, are shown in Table 2.

[0308] - Evaluation 5: As shown in Table 2, the extremely high density of He with a transmittance of 0.0 cm / min·atm was confirmed.

[0309] - Evaluation 6: As shown in Table 2, high ionic conductivity was confirmed.

[0310] - Evaluation 7: The He transmission rate after alkali impregnation was 0.0 cm / min·atm, the same as in Evaluation 5, confirming the excellent alkali resistance that the He transmission rate did not change even after alkali impregnation at a high temperature of up to 90°C for 1 week.

[0311] - Evaluation 8: As shown in Table 2, excellent dendrite tolerance was confirmed, with no short circuits caused by zinc dendrites even after 300 cycles.

[0312] Example B8 (refer to)

[0313] Except for the preparation of the raw material aqueous solution (II) as described in (5) and the addition of strontium based on impregnation treatment to replace (6) as described in Example B1, the LDH-like compound separator was prepared and evaluated in the same manner.

[0314] (Preparation of raw material aqueous solution (II))

[0315] Strontium nitrate (Sr(NO3)2) was prepared as a raw material. Strontium nitrate was weighed at a concentration of 0.015 mol / L and placed into a beaker. Ion-exchanged water was added to bring the total volume to 75 ml. The resulting solution was stirred to obtain the raw material aqueous solution (II).

[0316] (Strontium added based on impregnation treatment)

[0317] The raw material aqueous solution (II) and the LDH-like compound separator obtained in (4) above were sealed together in a Teflon (registered trademark) sealed container (autoclave container, internal volume 100 ml, outer sleeve made of stainless steel). At this time, the substrate was floated from the bottom of the Teflon (registered trademark) sealed container and fixed so that the solution was in contact with both sides of the substrate in a vertical position. Then, an immersion treatment was performed at 30°C for 6 hours, thereby adding strontium. After the specified time, the substrate was removed from the sealed container, washed with deionized water, and dried at 70°C for 10 hours, thereby obtaining the LDH-like compound separator with added strontium.

[0318] - Evaluation 2: Based on the results that the layered lattice stripes can be identified, it is confirmed that the LDH-like compound separator, except for the porous substrate, is a compound with a layered crystalline structure.

[0319] - Evaluation 3: As a result of EDS elemental analysis, Mg, Al, Ti, Y, and Sr, which are constituent elements of the LDH-like compound, were detected on the surface of the LDH-like compound separator. Furthermore, the composition ratios (atomic ratios) of Mg, Al, Ti, Y, and Sr on the surface of the LDH-like compound separator, calculated by EDS elemental analysis, are shown in Table 2.

[0320] - Evaluation 5: As shown in Table 2, the extremely high density of He with a transmittance of 0.0 cm / min·atm was confirmed.

[0321] - Evaluation 6: As shown in Table 2, high ionic conductivity was confirmed.

[0322] - Evaluation 7: The He transmission rate after alkali impregnation was 0.0 cm / min·atm, the same as in Evaluation 5, confirming the excellent alkali resistance that the He transmission rate did not change even after alkali impregnation at a high temperature of up to 90°C for 1 week.

[0323] - Evaluation 8: As shown in Table 2, excellent dendrite tolerance was confirmed, with no short circuits caused by zinc dendrites even after 300 cycles.

[0324] Example B9 (refer to)

[0325] Except for the preparation of the raw material aqueous solution (II) as described in (5) and the addition of barium based on impregnation treatment to replace (6) as described in Example B1, the LDH-like compound separator was prepared and evaluated in the same manner.

[0326] (Preparation of raw material aqueous solution (II))

[0327] Barium nitrate (Ba(NO3)2) was prepared as a raw material. Barium nitrate was weighed at a concentration of 0.015 mol / L and placed in a beaker. Ion-exchanged water was added to bring the total volume to 75 ml. The resulting solution was stirred to obtain an aqueous solution of the raw material (II).

[0328] (Barium added based on impregnation treatment)

[0329] The raw material aqueous solution (II) and the LDH-like compound separator obtained in (4) above were sealed together in a Teflon (registered trademark) sealed container (autoclave container, internal volume 100 ml, outer sleeve made of stainless steel). At this time, the substrate was floated from the bottom of the Teflon (registered trademark) sealed container and fixed so that the solution was in contact with both sides of the substrate in a vertical position. Then, a immersion treatment was performed at 30°C for 6 hours, thereby adding barium. After the specified time, the substrate was removed from the sealed container, washed with deionized water, and dried at 70°C for 10 hours, thereby obtaining the barium-added LDH-like compound separator.

[0330] - Evaluation 2: Based on the results that the layered lattice stripes can be identified, it is confirmed that the LDH-like compound separator, except for the porous substrate, is a compound with a layered crystalline structure.

[0331] - Evaluation 3: As a result of EDS elemental analysis, Al, Ti, Y, and Ba, which are constituent elements of the LDH-like compound, were detected on the surface of the LDH-like compound separator. Furthermore, the atomic ratios of Al, Ti, Y, and Ba on the surface of the LDH-like compound separator, calculated by EDS elemental analysis, are shown in Table 2.

[0332] - Evaluation 5: As shown in Table 2, the extremely high density of He with a transmittance of 0.0 cm / min·atm was confirmed.

[0333] - Evaluation 6: As shown in Table 2, high ionic conductivity was confirmed.

[0334] - Evaluation 7: The He transmission rate after alkali impregnation was 0.0 cm / min·atm, the same as in Evaluation 5, confirming the excellent alkali resistance that the He transmission rate did not change even after alkali impregnation at a high temperature of up to 90°C for 1 week.

[0335] - Evaluation 8: As shown in Table 2, excellent dendrite tolerance was confirmed, with no short circuits caused by zinc dendrites even after 300 cycles.

[0336] [Table 2]

[0337]

[0338] [Examples C1 and C2]

[0339] Examples C1 and C2 given below are reference examples related to LDH-like compound separators. It should be noted that the evaluation method for the LDH-like compound separators prepared in the following examples is the same as that for Examples A1 to A8, except that the composition ratio (atomic ratio) of Mg:Al:Ti:Y:In calculated in Evaluation 3 is used.

[0340] Example C1 (refer to)

[0341] (1) Preparation of porous polymer substrate

[0342] A commercially available polyethylene microporous membrane with a porosity of 50%, an average pore diameter of 0.1 μm, and a thickness of 20 μm was prepared as a polymer porous substrate and cut into 2.0 cm × 2.0 cm pieces.

[0343] (2) Coating a titanium dioxide-yttrium trioxide-alumina sol onto a porous polymer substrate.

[0344] Titanium oxide sol solution (M6, manufactured by Tagi Chemical Co., Ltd.), yttrium sol, and amorphous alumina solution (Al-ML15, manufactured by Tagi Chemical Co., Ltd.) were mixed at a molar ratio of Ti / (Y+Al) = 2 and a molar ratio of Y / Al = 8. The mixed solution was applied to the substrate prepared in (1) above by dip coating. The dip coating was performed by immersing the substrate in 100 ml of the mixed solution, then lifting it vertically and drying it at room temperature for 3 hours.

[0345] (3) Preparation of raw material aqueous solution

[0346] Magnesium nitrate hexahydrate (Mg(NO3)2·6H2O, manufactured by Kanto Chemical Co., Ltd.), indium sulfate n-hydrate (In2(SO4)3·nH2O, manufactured by Fuji Thin Film & Television Co., Ltd.), and urea ((NH2)2CO, manufactured by Sigma-Aldrich) were prepared as raw materials. Magnesium nitrate hexahydrate (0.0075 mol / L), indium sulfate n-hydrate (0.0075 mol / L), and urea (1.44 mol / L) were weighed and placed into a beaker. Ion-exchanged water was added to bring the total volume to 75 ml. The resulting solution was stirred to obtain an aqueous solution of the raw materials.

[0347] (4) Film formation based on hydrothermal treatment

[0348] The raw material aqueous solution and the impregnated substrate are sealed together in a Teflon (registered trademark) sealed container (autoclave container, internal volume 100ml, outer sleeve made of stainless steel). The substrate is then floated from the bottom of the Teflon (registered trademark) sealed container and fixed in place, vertically positioned so that the solution is in contact with both sides of the substrate. A hydrothermal treatment is then performed at 120°C for 22 hours, thereby forming an LDH-like compound on the surface and inside the substrate. After a specified time, the substrate is removed from the sealed container, washed with deionized water, and dried at 70°C for 10 hours, thereby forming a functional layer containing the LDH-like compound and In(OH)3 within the pores of the porous substrate. This yields an LDH-like compound separator.

[0349] (5) Densification based on roll pressing

[0350] The LDH-like compound separator described above was clamped using a pair of PET films (Lumirror manufactured by Toray Corporation, registered trademark, 40 μm thick) and rolled at a roller rotation speed of 3 mm / s, a roller heating temperature of 70°C, and a roller gap of 70 μm to obtain a further densified LDH-like compound separator.

[0351] (6) Evaluation Results

[0352] The obtained LDH-like compound separators were evaluated 1–8. The results are as follows.

[0353] - Evaluation 1: SEM image of the surface microstructure of the LDH-like compound separator (before rolling) obtained in Example C1 is as follows: Figure 17 As shown. Figure 17 As shown, cubic crystals were confirmed to exist on the surface of the LDH-like compound separator. Based on the EDS elemental analysis and X-ray diffraction results described later, the cubic crystals were presumed to be In(OH)3.

[0354] - Evaluation 2: Based on the results that the layered lattice stripes can be identified, it is confirmed that the LDH-like compound separator contains a compound with a layered crystalline structure.

[0355] - Evaluation 3: As a result of EDS elemental analysis, Mg, Al, Ti, Y, and In, which are constituent elements of the LDH-like compound and In(OH)3, were detected on the surface of the LDH-like compound separator. Furthermore, In, a constituent element of In(OH)3, was detected in the cubic crystals present on the surface of the LDH-like compound separator. It should be noted that the composition ratios (atomic ratios) of Mg, Al, Ti, Y, and In on the surface of the LDH-like compound separator calculated by EDS elemental analysis are shown in Table 3.

[0356] - Evaluation 4: Based on the peaks in the obtained XRD pattern, In(OH)3 was identified in the LDH-like compound separator. This identification was performed using the diffraction peaks of In(OH)3 recorded in JCPDS Card No. 01-085-1338.

[0357] - Evaluation 5: As shown in Table 3, the extremely high density of He with a transmittance of 0.0 cm / min·atm was confirmed.

[0358] - Evaluation 6: As shown in Table 3, high ionic conductivity was confirmed.

[0359] - Evaluation 7: The He transmission rate after alkali impregnation was 0.0 cm / min·atm, the same as in Evaluation 5, confirming the excellent alkali resistance that the He transmission rate did not change even after alkali impregnation at a high temperature of up to 90°C for 1 week.

[0360] - Evaluation 8: As shown in Table 3, excellent dendrite tolerance was confirmed, with no short circuits caused by zinc dendrites even after 300 cycles.

[0361] Example C2 (refer to)

[0362] Except for replacing (2) above with coating titanium dioxide-yttrium oxide sol as described below, the LDH-like compound separator was prepared and evaluated in the same manner as in Example C1.

[0363] (Coating titanium dioxide-yttrium oxide sol onto a porous polymer substrate)

[0364] Titanium oxide sol solution (M6, manufactured by Tagi Chemical Co., Ltd.) and yttrium sol were mixed at a Ti / Y (molar ratio) of 2. The mixed solution was then applied to the substrate prepared in (1) above by dip coating. The dip coating was performed by immersing the substrate in 100 ml of the mixed solution, then lifting it vertically and drying it at room temperature for 3 hours.

[0365] - Evaluation 1: SEM images of the surface microstructure of the LDH-like compound separator (before rolling) obtained in Example C2 are as follows: Figure 18 As shown. Figure 18 As shown, cubic crystals were confirmed to exist on the surface of the LDH-like compound separator. Based on the EDS elemental analysis and X-ray diffraction results described later, the cubic crystals were presumed to be In(OH)3.

[0366] - Evaluation 2: Based on the results that the layered lattice stripes can be identified, it is confirmed that the LDH-like compound separator contains a compound with a layered crystalline structure.

[0367] - Evaluation 3: As a result of EDS elemental analysis, Mg, Ti, Y, and In, which are constituent elements of the LDH-like compound and In(OH)3, were detected on the surface of the LDH-like compound separator. Furthermore, In, a constituent element of In(OH)3, was detected in the cubic crystals present on the surface of the LDH-like compound separator. It should be noted that the atomic ratios of Mg, Ti, Y, and In on the surface of the LDH-like compound separator, calculated by EDS elemental analysis, are shown in Table 3.

[0368] - Evaluation 4: Based on the peaks in the obtained XRD pattern, In(OH)3 was identified in the LDH-like compound separator. This identification was performed using the diffraction peaks of In(OH)3 recorded in JCPDS Card No. 01-085-1338.

[0369] - Evaluation 5: As shown in Table 3, the extremely high density of He with a transmittance of 0.0 cm / min·atm was confirmed.

[0370] - Evaluation 6: As shown in Table 3, high ionic conductivity was confirmed.

[0371] - Evaluation 7: The He transmission rate after alkali impregnation was 0.0 cm / min·atm, the same as in Evaluation 5, confirming the excellent alkali resistance that the He transmission rate did not change even after alkali impregnation at a high temperature of up to 90°C for 1 week.

[0372] - Evaluation 8: As shown in Table 3, excellent dendrite tolerance was confirmed, with no short circuits caused by zinc dendrites even after 300 cycles.

[0373] [Table 3]

[0374]

Claims

1. A zinc secondary battery, comprising the following battery elements, the battery elements including: A positive electrode plate, which includes a positive active material layer and a positive current collector; A negative electrode plate comprising a negative electrode active material layer and a negative electrode current collector, wherein the negative electrode active material layer contains at least one of the following selected from the group consisting of zinc, zinc alloys and zinc compounds. A layered double hydroxide compound separator, also known as an LDH-like compound separator, comprises an LDH-like compound and completely covers or encapsulates the negative electrode active material layer; and Electrolyte The zinc secondary battery is characterized in that... The positive electrode active material layer, the negative electrode active material layer, and the LDH-like compound separator are all quadrilateral in shape. The positive current collector has a positive current collector tab extending from one side of the positive active material layer, and the negative current collector has a negative current collector tab extending from one side of the negative active material layer opposite to the positive current collector tab, beyond the end of the LDH-like compound separator. Thus, the battery elements can collect electricity from opposite sides via the positive and negative current collector tabs. Furthermore, the outer edges of at least two adjacent sides of the LDH-like compound separator are closed, except for the side that overlaps with the negative electrode collector tab. The LDH-like compound is one of the following (a), (b), or (c). (a) A layered crystalline hydroxide and / or oxide comprising Mg, and at least one element selected from the group consisting of Ti, Y, and Al, containing at least Ti. (b) A layered crystalline hydroxide and / or oxide comprising (i) Ti, Y, and optionally Al and / or Mg, and (ii) at least one element M selected from the group consisting of In, Bi, Ca, Sr and Ba. (c) Layered crystalline hydroxides and / or oxides comprising Mg, Ti, Y, and optionally Al and / or In, In (c), the LDH-like compound exists in the form of a mixture with In(OH)3.

2. The zinc secondary battery according to claim 1, characterized in that, The negative electrode active material layer contains zinc oxide.

3. The zinc secondary battery according to claim 1 or 2, characterized in that, The zinc secondary battery also includes a liquid-retaining component, which is located between the negative electrode active material layer and the LDH-like compound separator, and completely covers or encapsulates the negative electrode active material layer.

4. The zinc secondary battery according to claim 3, characterized in that, The liquid-retaining component is made of non-woven fabric.

5. The zinc secondary battery according to claim 1 or 2, characterized in that, The battery elements are arranged such that the positive electrode plate, the negative electrode plate, and the LDH-like compound separator are each longitudinally arranged, with one side of the closed outer edge of the LDH-like compound separator being the lower end. As a result, the positive electrode current collector and the negative electrode current collector extend laterally from opposite sides of the battery elements.

6. The zinc secondary battery according to claim 5, characterized in that, The outer edge of the upper side of the LDH-like compound separator is open, or the outer edge of the upper side of the LDH-like compound separator is closed and a vent is provided on a portion of the closed outer edge.

7. The zinc secondary battery according to claim 6, characterized in that, The zinc secondary battery also includes a casing that houses the battery components.

8. The zinc secondary battery according to claim 1 or 2, characterized in that, The zinc secondary battery further comprises: a positive current collector plate connected to the end of the positive current collector tab, and a negative current collector plate connected to the end of the negative current collector tab.

9. The zinc secondary battery according to claim 1 or 2, characterized in that, The number of battery elements is two or more, and the two or more battery elements are housed together in the casing.

10. The zinc secondary battery according to claim 1 or 2, characterized in that, The closed state of the outer edge of the LDH-like compound separator is achieved by bending the LDH-like compound separator and / or sealing the LDH-like compound separators with each other.

11. The zinc secondary battery according to claim 1 or 2, characterized in that, The LDH-like compound separator comprises an LDH-like compound and a porous substrate. The LDH-like compound seals the pores of the porous substrate, thereby enabling the LDH-like compound separator to exhibit hydroxide ion conductivity and air impermeability.

12. The zinc secondary battery according to claim 11, characterized in that, The porous substrate is made of polymer materials.

13. The zinc secondary battery according to claim 12, characterized in that, The LDH-like compound is embedded throughout the thickness direction of the porous substrate.

14. The zinc secondary battery according to claim 1 or 2, characterized in that, The positive electrode active material layer contains nickel hydroxide and / or nickel hydroxy oxide, thereby forming the zinc secondary battery as a nickel-zinc secondary battery.

15. The zinc secondary battery according to claim 1 or 2, characterized in that, The positive electrode active material layer is an air electrode, thereby forming the zinc secondary battery as an air-zinc secondary battery.

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