Air electrode / separator assembly and zinc-air secondary battery

Abstract

The present application provides an air electrode / LDH separator joint body which does not impair the functions of the LDH separator and the air electrode, and which can well construct a zinc-air secondary battery in a stacked cell form suitable for supplying high voltage and large current. The air electrode / LDH separator joint body is provided with: a rigid porous layer having rigidity and air permeability, the rigidity being defined by a displacement ratio in the compression direction being less than 3% under pressurization at 0.1 MPa; an air electrode layer covering both faces of the rigid porous layer, or both faces and end faces (at least one end face being excluded) of the rigid porous layer; and a layered double hydroxide (LDH) separator covering the outside of the air electrode layer. i) The rigid porous layer is made of a metal or an electrically conductive ceramic, whereby the rigid porous layer itself functions as a positive electrode current collector, or ii) the rigid porous layer is made of an insulating material, and the rigid porous layer is covered with a porous metal layer, whereby the porous metal layer functions as a positive electrode current collector.

Description

Technical Field

[0001] This invention relates to an air electrode / separator junction and a zinc-air secondary battery. Background Technology

[0002] One potential candidate for innovative batteries is the metal-air secondary battery. Because oxygen is supplied from the air as the positive electrode active material, the space within the battery container can be maximized for filling the negative electrode active material, thus theoretically enabling a higher energy density. For example, in a zinc-air secondary battery using zinc as the negative electrode active material, an alkaline aqueous solution such as potassium hydroxide is used as the electrolyte, and a separator (wall) is used to prevent short circuits between the positive and negative electrodes. During discharge, as shown in the following reaction equation, O2 is reduced to OH- on the air electrode (positive electrode) side. - On the other hand, at the negative electrode, zinc is oxidized to form ZnO.

[0003] Positive electrode: O2 + 2H2O + 4e - →4OH -

[0004] Negative electrode: 2Zn + 4OH - →2ZnO+2H2O+4e -

[0005] However, for zinc-air batteries, nickel-zinc batteries, and other zinc-based rechargeable batteries, it is known that during charging, metallic zinc precipitates as dendrites from the negative electrode, penetrating the gaps in the non-woven fabric separator and reaching the positive electrode, resulting in a short circuit. This short circuit caused by zinc dendrites leads to a shortened charge-discharge cycle life. Furthermore, zinc-air batteries also suffer from the problem that carbon dioxide from the air passes through the air electrode and dissolves in the electrolyte, precipitating basic carbonates and degrading battery performance. The same problems can also occur in lithium-air batteries.

[0006] To address the aforementioned problems, batteries incorporating layered double hydroxide (LDH) separators that selectively allow hydroxide ions to pass through while preventing zinc dendrites from penetrating have been proposed. For example, Patent Document 1 (International Publication No. 2013 / 073292) discloses that in a zinc-air secondary battery, an LDH separator is placed between the air electrode and the negative electrode to simultaneously prevent short circuits between the positive and negative electrodes caused by zinc dendrites and the introduction of carbon dioxide. 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. Furthermore, 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). This method includes the steps of uniformly attaching a starting material capable of providing a crystal growth starting point for LDH to the porous substrate, and performing hydrothermal treatment on the porous substrate in an aqueous solution of raw materials to form a dense LDH film on the surface of the porous substrate. Moreover, Patent Document 4 (International Publication No. 2019 / 069762) discloses a method of completely covering or encapsulating the negative electrode active material layer with a liquid-retaining component and an LDH separator, thereby efficiently producing a negative electrode structure suitable for zinc secondary batteries (especially their stacked batteries) that can prevent zinc dendrite extension.

[0007] In addition, in the field of metal-air secondary batteries such as zinc-air secondary batteries, air electrode / separator joints with an air electrode layer disposed on an LDH separator have been proposed. Patent Document 5 (International Publication No. 2015 / 146671) discloses an air electrode / separator joint having an air electrode layer comprising an air electrode catalyst, an electron-conducting material, and a hydroxide ion-conducting material on an LDH separator. Furthermore, Patent Document 6 (International Publication No. 2018 / 163353) discloses a method for manufacturing an air electrode / separator joint by directly bonding an air electrode layer comprising LDH and carbon nanotubes (CNTs) to an LDH separator.

[0008] Existing technical documents

[0009] Patent documents

[0010] Patent Document 1: International Publication No. 2013 / 073292

[0011] Patent Document 2: International Publication No. 2016 / 076047

[0012] Patent Document 3: International Publication No. 2016 / 067884

[0013] Patent Document 4: International Publication No. 2019 / 069762

[0014] Patent Document 5: International Publication No. 2015 / 146671

[0015] Patent Document 6: International Publication No. 2018 / 163353 Summary of the Invention

[0016] As described above, metal-air secondary batteries employing LDH separators have the excellent advantages of simultaneously preventing short circuits between the positive and negative electrodes caused by metal dendrites and preventing the introduction of carbon dioxide. Furthermore, they also have the advantage of suppressing the evaporation of moisture contained in the electrolyte due to the density of the LDH separator. Moreover, to obtain high voltage and high current, it is only necessary to construct a cascaded battery by alternately arranging multiple air electrode / LDH separator joints and multiple negative electrode plates. However, various technical constraints or requirements exist in constructing cascaded batteries, such as a) the need for efficient introduction of external air into the air electrode, b) the impermeability of the LDH separator due to its density, and c) the desire for a tight seal between the air electrode / separator / negative electrode plate to improve battery performance. Therefore, there is a need for an air electrode / LDH separator joint that can be used to construct cascaded batteries without compromising the original functions of the LDH separator and zinc-air secondary batteries.

[0017] The inventors of this invention have recently come to the insight that by combining a rigid porous layer, an air electrode layer, and an LDH separator having specified rigidity and breathability, an air electrode / LDH separator assembly can be provided that does not damage the original functions of the LDH separator and the air electrode, and can be well constructed into a zinc-air secondary battery suitable for supplying high voltage and high current stacked battery configuration.

[0018] Therefore, one object of the present invention is to provide an air electrode / LDH separator assembly that does not damage the original functions of the LDH separator and the air electrode, and can be well constructed into a zinc-air secondary battery suitable for supplying high voltage and high current in a stacked battery configuration. Another object of the present invention is to provide a zinc-air secondary battery in a stacked battery configuration employing multiple of these air electrode / separator assemblies.

[0019] According to one aspect of the present invention, an air electrode / separator joint is provided, wherein it comprises:

[0020] A rigid porous layer that is both rigid and breathable, the rigidity being defined by a displacement ratio in the compression direction of less than 3% under a pressure of 0.1 MPa;

[0021] An air electrode layer that covers both sides of the rigid porous layer, or both sides and end faces (excluding at least one end face) of the rigid porous layer; and

[0022] A layered double hydroxide (LDH) separator covers the outer side of the air electrode layer.

[0023] The air electrode / separator joint is characterized in that...

[0024] i) The rigid porous layer is made of metal or conductive ceramic, thereby functioning as a positive current collector, or...

[0025] ii) The rigid porous layer is made of an insulating material and is covered by a porous metal layer, wherein the porous metal layer functions as a positive current collector.

[0026] According to another aspect of the present invention, a zinc-air secondary battery is provided, which is equipped with the aforementioned air electrode / separator junction.

[0027] The zinc-air secondary battery is characterized by having:

[0028] Multiple air electrode / split plate joints;

[0029] Multiple negative electrode plates are alternately arranged with the air electrode / separator junction and include a negative electrode active material layer and a negative electrode current collector. The negative electrode active material layer contains at least one of the following: zinc, zinc oxide, zinc alloy and zinc compound.

[0030] An electrolyte, which is impregnated in the negative electrode plate and the LDH separator; and

[0031] The battery casing houses the multiple air electrode / separator joints, the multiple negative electrode plates, and the electrolyte in a vertical arrangement.

[0032] The multiple negative electrode plates and the electrolyte are housed within a sealed space defined by the battery casing and the multiple air electrode / separator joints, with some remaining space at the top. The multiple air electrode / separator joints can contact the outside air through the openings in the battery casing.

[0033] The battery casing is further provided with a pressure relief valve at a position facing the upper remaining space or at a position communicating with the upper remaining space, which can release any gas that may be generated inside the battery.

[0034] According to a first preferred embodiment of the present invention, the aforementioned zinc-air secondary battery is provided, characterized in that:

[0035] The multiple air electrode / separator joints are configured such that the end face of the rigid porous layer not covered by the LDH separator faces upward.

[0036] The zinc-air secondary battery has the following features:

[0037] A positive current collector is connected to the upper end of the plurality of positive current collectors via the end face of the rigid porous layer that is not covered by the LDH separator;

[0038] A positive current collector terminal, which is connected to the positive current collector component and extends from the battery casing;

[0039] Multiple negative current collector tabs, extending laterally from the ends of the multiple negative current collectors on their lateral sides; and

[0040] A negative current collector terminal is connected to the plurality of negative current collector tabs and extends from the battery casing.

[0041] According to a second preferred embodiment of the present invention, the aforementioned zinc-air secondary battery is provided, characterized in that:

[0042] The multiple air electrode / separator joints are configured such that the end face of the rigid porous layer not covered by the LDH separator faces upward.

[0043] The zinc-air secondary battery has the following features:

[0044] A positive current collector is connected to the upper end of the plurality of positive current collectors via the end face of the rigid porous layer that is not covered by the LDH separator;

[0045] A positive current collector terminal, which is connected to the positive current collector component and extends from the battery casing;

[0046] Multiple negative current collector tabs, extending upwards and / or laterally from the upper end of the multiple negative current collectors; and

[0047] A negative current collector terminal is connected to the plurality of negative current collector tabs and extends from the battery casing.

[0048] According to a third preferred embodiment of the present invention, the aforementioned zinc-air secondary battery is provided, characterized in that:

[0049] The multiple air electrode / separator joints are configured such that the end face of the rigid porous layer not covered by the LDH separator faces downward.

[0050] The zinc-air secondary battery has the following features:

[0051] A positive current collector is connected to the lower end of the plurality of positive current collectors via the end face of the rigid porous layer that is not covered by the LDH separator;

[0052] A positive current collector terminal, which is connected to the positive current collector component and extends from the battery casing;

[0053] A negative current collector component, disposed within the upper remaining space, and connected to the upper end of the plurality of negative current collectors; and

[0054] A negative current collector terminal is connected to the negative current collector component and extends from the battery casing.

[0055] According to a fourth preferred embodiment of the present invention, the aforementioned zinc-air secondary battery is provided, characterized in that:

[0056] The multiple air electrode / separator joints are configured such that the end face of the rigid porous layer not covered by the LDH separator faces downwards.

[0057] The zinc-air secondary battery has the following features:

[0058] A positive current collector is connected to the lower end of the plurality of positive current collectors via the end face of the rigid porous layer that is not covered by the LDH separator;

[0059] A positive current collector terminal, which is connected to the positive current collector component and extends from the battery casing;

[0060] A negative current collector component, disposed within the upper remaining space, and connected to the upper end of the plurality of negative current collectors; and

[0061] A negative current collector terminal, which is connected to the negative current collector component and extends from the upper surface of the battery casing.

[0062] The LDH separator is configured as an integrally connected strip opposite to the multiple air electrode / separator joints and the multiple negative electrode plates. The strip-shaped LDH separator has a tortuous structure, and the air electrode layer, the rigid porous layer and the negative electrode plate are alternately housed in multiple divisions formed by the tortuous structure, thereby separating the air electrode layer and the negative electrode plate from each other by means of the LDH separator.

[0063] According to a fifth preferred embodiment of the present invention, the aforementioned zinc-air secondary battery is provided, characterized in that:

[0064] The multiple air electrode / septum assembly is configured such that the end face of the rigid porous layer not covered by the LDH septum faces downward;

[0065] The zinc-air secondary battery has the following features:

[0066] A positive current collector is connected to the lower end of the plurality of positive current collectors via the end face of the rigid porous layer that is not covered by the LDH separator;

[0067] A positive current collector terminal, which is connected to the positive current collector component and extends from the battery casing;

[0068] A negative current collector component, disposed within the upper remaining space, and connected to the upper end of the plurality of negative current collectors; and

[0069] A negative current collector terminal, which is connected to the negative current collector component and extends from the side of the battery casing.

[0070] The LDH separator is configured as an integrally connected strip opposite to the multiple air electrode / separator joints and the multiple negative electrode plates. The strip-shaped LDH separator has a tortuous structure, and the air electrode layer, the rigid porous layer and the negative electrode plate are alternately housed in multiple divisions formed by the tortuous structure, thereby separating the air electrode layer and the negative electrode plate from each other by means of the LDH separator. Attached Figure Description

[0071] Figure 1A This is a schematic cross-sectional view illustrating one embodiment (first preferred embodiment) of a zinc-air secondary battery having an air electrode / separator junction, which is one of the various embodiments of the present invention.

[0072] Figure 1B yes Figure 1A The diagram shows a cross-sectional view of the zinc-air secondary battery along line 1B-1B.

[0073] Figure 1C yes Figure 1A The top view of the zinc-air secondary battery shown.

[0074] Figure 2A This is a schematic cross-sectional view illustrating another embodiment (second preferred embodiment) of a zinc-air secondary battery having an air electrode / separator junction, which is one of the various embodiments of the present invention.

[0075] Figure 2B yes Figure 2A The diagram shows a cross-sectional view of the zinc-air secondary battery along line 2B-2B.

[0076] Figure 2C yes Figure 2AThe top view of the zinc-air secondary battery shown.

[0077] Figure 2D It means Figure 2A A simplified cross-sectional view of a modified example of the configuration of the pressure relief valve and the negative electrode current collector in a zinc-air secondary battery.

[0078] Figure 3A This is a schematic cross-sectional view illustrating another embodiment (third preferred embodiment) of a zinc-air secondary battery having an air electrode / separator junction, which is one of the various embodiments of the present invention.

[0079] Figure 3B yes Figure 3A The diagram shows a cross-sectional view of the zinc-air secondary battery along line 3B-3B.

[0080] Figure 3C yes Figure 3A The top view of the zinc-air secondary battery shown.

[0081] Figure 3D yes Figure 3A The image shows a bottom view of a zinc-air secondary battery.

[0082] Figure 4A This is a schematic cross-sectional view illustrating another embodiment (fourth preferred embodiment) of a zinc-air secondary battery having an air electrode / separator junction, which is one aspect of the present invention.

[0083] Figure 4B yes Figure 4A The diagram shows a cross-sectional view of the zinc-air secondary battery along line 4B-4B.

[0084] Figure 4C yes Figure 4A The top view of the zinc-air secondary battery shown.

[0085] Figure 4D yes Figure 4A The image shows a bottom view of a zinc-air secondary battery.

[0086] Figure 4E It is a summary. Figure 4A A simplified cross-sectional view of a modified example of a zinc-air secondary battery.

[0087] Figure 5A This is a schematic cross-sectional view illustrating another embodiment (fifth preferred embodiment) of a zinc-air secondary battery having an air electrode / separator junction, which is one aspect of the present invention.

[0088] Figure 5B yes Figure 5A The diagram shows a cross-sectional view of the zinc-air secondary battery along line 5B-5B.

[0089] Figure 5C yes Figure 5A The top view of the zinc-air secondary battery shown.

[0090] Figure 5D yes Figure 5A The image shows a bottom view of a zinc-air secondary battery.

[0091] Figure 5E It is a summary. Figure 5A A simplified cross-sectional view of a modified example of a zinc-air secondary battery.

[0092] Figure 6A This is a diagram illustrating one embodiment of the rigid porous layer used in this invention.

[0093] Figure 6B yes Figure 6A The top view of the rigid porous layer shown.

[0094] Figure 7A This is a diagram illustrating another embodiment of the rigid porous layer used in this invention.

[0095] Figure 7B yes Figure 7A The top view of the rigid porous layer shown.

[0096] Figure 8 This is a simplified cross-sectional view of an example of an LDH partition.

[0097] Figure 9 This is a simplified cross-sectional view of a preferred embodiment of the air electrode / septum assembly (excluding the rigid porous layer).

[0098] Figure 10 This is a simplified cross-sectional view of another preferred embodiment of the air pole / septum assembly (excluding the rigid porous layer).

[0099] Figure 11 This is a schematic cross-sectional view of one scheme in which plate-like particles are attached to the surface of the LDH partition perpendicularly or obliquely. Detailed Implementation

[0100] Air electrode / partition joint

[0101] Figures 1A-1CThe diagram illustrates one embodiment of a zinc-air secondary battery 10 comprising an air electrode / separator junction 12. The air electrode / separator junction 12 comprises: a rigid porous layer 14, an air electrode layer 16, and a layered double hydroxide (LDH) separator 18. The rigid porous layer 14 is both rigid and permeable. This rigidity is defined by a displacement of less than 3% in the compression direction (typically the thickness direction) of the rigid porous layer 14 under a pressure of 0.1 MPa. The air electrode layer 16 covers both sides of the rigid porous layer 14, or both sides and one end face (excluding at least one end face). The LDH separator 18 covers the outer side of the air electrode layer 16. Furthermore, i) the rigid porous layer 14 can be made of a metal such as a porous metal 14a or a metal mesh 14b, or a conductive ceramic, thereby enabling the rigid porous layer 14 itself to function as a positive current collector. Furthermore, ii) the rigid porous layer 14 can also be made of an insulating material such as porous resin 14c, and the rigid porous layer 14 is covered by a porous metal layer 15, thereby the porous metal layer 15 can function as a positive electrode current collector. It should be noted that, for ease of explanation, the zinc-air secondary battery 10 shown in FIG1 depicts a secondary battery employing both forms of the air electrode / separator joint 12 described above (i) and ii). However, the air electrode / separator joint 12 of the present invention can employ only the configuration described in i), or only the configuration described in ii). In summary, by combining the rigid porous layer 14, the air electrode layer 16, and the LDH separator 18, which have specified rigidity and permeability, an air electrode / LDH separator joint 12 can be provided that does not impair the original functions of the LDH separator 18 and the air electrode layer 16, and can well construct a stacked battery configuration for the zinc-air secondary battery 10. Furthermore, the zinc-air secondary battery 10 in the form of a stacked battery can achieve high voltage and high current, which are not possible in a single-cell zinc-air secondary battery.

[0102] As described above, metal-air secondary batteries employing LDH separators have various excellent advantages. However, there are various technical constraints or requirements in constructing stacked batteries, such as a) the air electrode needs to efficiently introduce external air, b) the LDH separator being airtight and watertight due to its density, and c) the need for a tight seal between the air electrode / separator / negative electrode plate to improve battery performance. In this regard, the air electrode / separator joint 12 according to the present invention can satisfy the above-mentioned technical constraints or requirements, and can well construct a zinc-air secondary battery 10 that does not damage the original function of the LDH separator 18 and the air electrode layer 16 and is suitable for supplying high voltage and high current in a stacked battery configuration.

[0103] That is, the rigid porous layer 14 possesses both rigidity and breathability, allowing it to be housed within the battery container and pressurized together with other battery elements (such as negative electrodes) in a direction that ensures the battery elements are tightly sealed together. This rigidity is defined by the proportion of displacement in the compression direction being less than 3% when pressurized at 0.1 MPa. This pressurization is particularly advantageous in cases where multiple air electrode / separator joints 12 and multiple negative electrode plates 20 are alternately assembled into the battery casing 28 to form a stacked battery. Similarly, it is also advantageous in cases where multiple stacked batteries are housed in a single module container to form a battery module. For example, by pressurizing the zinc-air secondary battery 10, not only can the battery elements be tightly packed into the battery casing 28 with good space efficiency, but the gap between the negative electrode plate 20 and the LDH separator 18 that allows for zinc dendrite growth is minimized (preferably without a gap), thereby expecting to more effectively prevent zinc dendrite extension. Furthermore, although pressure is applied in the direction that seals the various battery components together, the rigid porous layer 14, due to its permeability, can function as a gas flow path, acting as both a spacer (and sometimes a positive electrode current collector). This allows sufficient external air (especially oxygen and water vapor) required for the positive electrode reaction to be introduced into the air electrode layer 16. As a result, the potential catalytic performance of the air electrode layer 16 can be maximized.

[0104] The rigid porous layer 14 possesses both rigidity and permeability. This rigidity is defined by a displacement ratio in the compression direction of less than 3% under a pressure of 0.1 MPa. Whether the displacement ratio in the compression direction of the rigid porous layer 14 is less than 3% under a pressure of 0.1 MPa can be determined by evaluating the relationship between load and displacement using a compression testing machine. For example, using a Shimadzu AGX (250N) compression testing machine, each test piece is cut into 30 mm square pieces. A crosshead feed speed of 0.5 mm / min is applied along the thickness direction of the test piece, and the displacement corresponding to the load is calculated. The displacement ratio (%) can be obtained by dividing the displacement D of the test piece thickness at 0.1 MPa by the initial thickness T of the test piece and multiplying by 100 (=(D / T)×100). The permeability of the rigid porous layer 14 should be sufficient to allow external air (especially oxygen and water vapor) required for the positive electrode reaction to pass through the rigid porous layer 14 and reach the air electrode layer 16. The thickness of the rigid porous layer 14 is sufficient to ensure air permeability and is not particularly limited, but preferably 0.3 mm or more, more preferably 0.5 mm or more, and even more preferably 1.0 mm or more. The upper limit of the thickness of the rigid porous layer 14 is not particularly limited, but typically 5.0 mm or less, and more typically 3.0 mm or less.

[0105] The rigid porous layer 14 can be made of metal or conductive ceramic. Accordingly, the rigid porous layer 14 itself can function as a positive current collector. That is, the rigid porous layer 14 itself can function as a gas flow path that serves as both a spacer and a positive current collector. The rigid porous layer 14 is preferably made of metal. Preferred examples of the metal constituting the rigid porous layer 14 include stainless steel, titanium, nickel, brass, and copper. The shape of the rigid porous layer 14 made of metal is not particularly limited as long as the required rigidity and permeability are ensured. Preferred examples include porous metal 14a, metal mesh 14b, and a metal plate with an uneven shape 14d (see reference). Figure 7B Examples of porous metal 14a include foamed metals, sintered porous metals, and other metal products with open pores. Examples of metal mesh 14b include: laminated metal meshes, or metal meshes in a laminated form, for example, such as... Figure 6A and 6B As shown, it can be a waffle-grid-like layered product. For example... Figure 7A and 7B As shown, the metal plate 14d, which has an uneven shape, can be a component obtained by corrugating a porous metal plate such as a perforated metal. By adopting a laminated shape or an uneven shape, the rigid porous layer 14 can ensure the desired air permeability and be set to the desired thickness. It should be noted that when the metal material constituting the rigid porous layer 14 is a microporous material, liquid absorption can be expected, and it can also function as a water storage part for the water required for the positive electrode reaction.

[0106] Alternatively, the rigid porous layer 14 can also be made of an insulating material. Preferred examples of the insulating material constituting the rigid porous layer 14 include insulating resin. The shape of the rigid porous layer 14 made of insulating resin is not particularly limited as long as the required rigidity and air permeability are ensured; preferred examples include porous resin 14c and resin plates with an uneven shape. When the rigid porous layer 14 is made of an insulating material, it is preferable to cover the rigid porous layer 14 with a porous metal layer 15. Accordingly, the rigid porous layer 14 itself is insulating, and the surface covered by the porous metal layer 15 can function as a positive electrode current collector. Preferred examples of the porous metal layer 15 include metal mesh, etc. It should be noted that when the insulating material constituting the rigid porous layer 14 is a hydrophilic microporous material, liquid absorption is expected, and it can also function as a water reservoir required for the positive electrode reaction.

[0107] The air electrode layer 16 is configured to cover both sides of the rigid porous layer 14, and also cover the end faces if necessary; however, for at least one end face of the rigid porous layer 14 (e.g., ...), ... Figures 1A-1C The upper end face of the middle, described later Figures 3A-3C The lower end face of the layer is designed to ensure a path for introducing external air into the rigid porous layer 14, preventing it from being covered by the air electrode layer 16. The air electrode layer 16 can be any known structure commonly used in zinc-air secondary batteries and is not particularly limited.

[0108] LDH separator 18 is configured to cover the outer side of air electrode layer 16. LDH separator 18 is defined as a separator comprising layered double hydroxide (LDH) and / or LDH-like compounds (hereinafter collectively referred to as hydroxide ion-conducting layered compounds), specifically utilizing the hydroxide ion conductivity of the hydroxide ion-conducting layered compounds to selectively allow hydroxide ions to pass through. In this specification, "LDH-like compounds" refers to hydroxides and / or oxides with a layered crystalline structure that may not be called LDH but is similar to LDH, and can be called equivalents of LDH. However, as a broad definition, "LDH" can also be interpreted as substances that include not only LDH but also LDH-like compounds. This LDH separator can be a separator known as those disclosed in Patent Documents 1-6, and is preferably an LDH separator composited with a porous substrate.

[0109] like Figure 8 As shown in summary, the particularly preferred LDH separator 18 comprises a porous substrate 18a made of polymeric material and a hydroxide ion-conducting layered compound 18b that seals the pores P of the porous substrate. This embodiment of the LDH separator 18 will be described below. Because it includes the porous substrate 18a made of polymeric material, it can bend even under pressure and is not prone to cracking. Therefore, it is extremely advantageous when housed within the battery casing 28 as described above and pressurized together with other battery components (such as the negative electrode plate 20) in a direction that seals the battery components together. Furthermore, the LDH separator 18 containing the porous substrate 18a made of polymeric material can be flexible and heat-fusible, thus allowing it to be bent or to be overlapped and heat-fused for sealing. For example, the LDH separator 18 can be wrapped around the outer periphery of the rigid porous layer 14 with an air electrode layer 16 in between (see [reference]). Figure 1A The outer peripheral portion of the rigid porous layer 14 made of metal mesh 14b and the outer peripheral portion of the rigid porous layer 14 made of porous resin 14c). Alternatively, LDH separators 18 can be sandwiched between the two sides of the rigid porous layer 14 with air electrode layers 16, and the protruding portions of the LDH separators 18 at their ends can be overlapped and heat-sealed (see reference). Figure 1A(The outer periphery of the rigid porous layer 14 made of porous metal 14a). In summary, by adopting the above configuration, the area containing the air electrode layer 16 and the area containing the negative electrode plate 20 can be reliably separated by means of the LDH separator 18 in a manner that ensures air and water impermeability while allowing selective passage of hydroxide ions. It should be noted that, from the viewpoint of improving productivity, it is preferable to pre-form the air electrode layer 16 in the LDH separator 18 into a form of "separator with attached air electrode", and to enclose or sandwich the rigid porous layer 14 with this separator with attached air electrode, thereby simultaneously arranging the air electrode layer 16 and the LDH separator 18 at the outer periphery of the rigid porous layer 14.

[0110] The portion of the air electrode layer 16 and the LDH separator 18, i.e. the air electrode / separator joint 12, other than the rigid porous layer 14, can adopt a known configuration as disclosed in Patent Documents 5 and 6. Hereinafter, a preferred air electrode / separator joint 12 (the portion other than the rigid porous layer) will be described.

[0111] Zinc-air secondary batteries

[0112] like Figures 1A-1CAs shown, a zinc-air secondary battery 10 can be constructed using an air electrode / separator junction 12. The zinc-air secondary battery 10 includes: multiple air electrode / separator junctions 12, multiple negative electrode plates 20, an electrolyte 26, and a battery casing 28. The multiple air electrode / separator junctions 12 and the multiple negative electrode plates 20 are alternately arranged, thereby forming a stacked battery configuration suitable for supplying high voltage and high current. The negative electrode plate 20 includes a negative electrode active material layer 22 and a negative electrode current collector 24. The negative electrode active material layer 22 comprises at least one element selected from the group consisting of zinc, zinc oxide, zinc alloys, and zinc compounds. The electrolyte 26 is impregnated within the negative electrode plate 20 and the LDH separator 18. The multiple air electrode / separator junctions 12, the multiple negative electrode plates 20, and the electrolyte 26 are longitudinally arranged within the battery casing 28. Multiple negative electrode plates 20 and electrolyte 26 are housed within a sealed space defined by the battery casing 28 and multiple air electrode / separator joints 12, leaving an upper residual space 30. The multiple air electrode / separator joints 12 can contact the outside air through the opening 28a of the battery casing 28. The battery casing 28 also has a pressure relief valve 32 at a position facing or communicating with the upper residual space 30, capable of releasing any gas that may be generated inside the battery. The LDH separator 18 is highly airtight, thus hindering gas release to the outside when gas is rapidly generated inside the battery due to overcharging, etc. However, according to this design, the space within the battery casing 28 that houses the negative electrode plates 20 has an upper residual space 30 and a pressure relief valve 32, thereby safely and quickly releasing any gas generated inside the battery to the outside of the battery casing 28 without damaging the battery casing 28 or the battery elements contained therein. That is, the zinc-air secondary battery 10 has an extremely high safety profile. It should be noted that the battery casing 28 may have an injection port (not shown) for injecting electrolyte 26.

[0113] The negative electrode plate 20 includes a negative electrode active material layer 22 and a negative electrode current collector 24. The negative electrode active material layer 22 comprises at least one material selected from the group consisting of zinc, zinc oxide, zinc alloys, and zinc compounds. Preferred examples of the negative electrode current collector 24 include copper foil, copper mesh, and copper perforated mesh. The electrolyte 26 is preferably an aqueous solution of an alkali metal hydroxide, such as potassium hydroxide solution. The battery casing 28 only needs to have resistance to the electrolyte 26 (i.e., alkali resistance), and is not particularly limited; it is preferably made of resins such as polyolefin resin, ABS resin, and modified polyphenylene ether. The pressure relief valve 32 only needs to have a structure capable of releasing gas generated inside the battery to the outside of the battery, and is not particularly limited; a check valve can be used.

[0114] Figures 1A-1CThis illustration shows a zinc-air secondary battery 10 according to a first preferred embodiment of the present invention. In this embodiment, multiple air electrode / separator joints 12 are configured such that the end face of the rigid porous layer 14 not covered by the LDH separator 18 faces upward. The zinc-air secondary battery 10 has: a positive electrode current collector 17, a positive electrode current collector terminal 34, a negative electrode current collector tab 25, and a negative electrode current collector terminal 36. The positive electrode current collector 17 is connected to the upper end of multiple positive electrode current collectors (in the example shown, porous metal 14a, metal mesh 14b, and porous metal layer 15 are positive electrode current collectors) via the end face of the rigid porous layer 14 not covered by the LDH separator 18. The positive electrode current collector terminal 34 is connected to the positive electrode current collector 17 and extends from the battery casing 28. Multiple negative electrode current collector tabs 25 extend laterally from the lateral ends of the multiple negative electrode current collectors 24. Multiple negative current collector tabs 25 are connected to negative current collector terminals 36, which extend from the battery casing 28.

[0115] In this way, the zinc-air secondary battery 10 of this solution is configured such that positive electrode current collection and external air introduction are performed at the top of the battery, and negative electrode current collection is performed at the lateral end, which is a configuration with good space efficiency. Therefore, the positive electrode current collection component 17 preferably has a porous structure with ventilation. In this case, the positive electrode current collection component 17 with a porous structure with ventilation is connected to the opening 28a, thereby allowing external air to be introduced into the rigid porous layer 14. Examples of positive electrode current collection components 17 with a porous structure with ventilation can be metal mesh, metal nonwoven fabric, perforated metal, etc. A fan 38 is preferably further provided above the battery casing 28, which is used to introduce air into the rigid porous layer 14 through the end face of the rigid porous layer 14 not covered by the LDH separator 18. Accordingly, the positive electrode reaction in the air electrode layer 16 can be promoted. From the perspective of space efficiency, the pressure relief valve 32 and the liquid injection port (not shown) are preferably located on the upper surface or side of the battery casing 28 (e.g., in a space that communicates with the negative electrode current collector 25).

[0116] Figures 2A-2CThe diagram illustrates a zinc-air secondary battery 10' according to a second preferred embodiment of the present invention. In this embodiment, multiple air electrode / separator junctions 12 are configured such that the end face of the rigid porous layer 14 not covered by the LDH separator 18 faces upward. The zinc-air secondary battery 10' has: a positive current collector 17, a positive current collector terminal 34, a negative current collector tab 25, and a negative current collector terminal 36. The positive current collector 17 is connected to the upper end of multiple positive current collectors (in the example shown, porous metal 14a, metal mesh 14b, and porous metal layer 15 are positive current collectors) via the end face of the rigid porous layer 14 not covered by the LDH separator 18. The positive current collector terminal 34 is connected to the positive current collector 17 and extends from the battery casing 28. Multiple negative current collector tabs 25 extend upward and / or laterally from the upper end of the multiple negative current collectors. Multiple negative current collector tabs 25 are connected to negative current collector terminals 36, which extend from the battery casing 28. It should be noted that in the zinc-air secondary battery 10' of the second preferred embodiment, the... Figures 1A-1C The components of the zinc-air secondary battery 10 shown are marked with the same symbols, and the description of the components with the same symbols in relation to the zinc-air secondary battery 10 also applies to the second preferred embodiment.

[0117] In this way, the zinc-air secondary battery 10' of this scheme is configured with positive electrode current collection, negative electrode current collection, and external air introduction at the top of the battery, resulting in a space-efficient configuration. However, it can also be configured as follows... Figure 2D The negative electrode current collector is shown at the lateral end. In summary, the positive electrode current collector 17 preferably has a porous structure with ventilation. In this case, the positive electrode current collector 17 with a porous structure with ventilation communicates with the opening 28a, thereby allowing external air to be introduced into the rigid porous layer 14. Examples of the positive electrode current collector 17 with a porous structure with ventilation include metal mesh, metal nonwoven fabric, perforated metal, etc. A fan 38 is preferably further provided above the battery casing 28, which is used to introduce air into the rigid porous layer 14 via the end face of the rigid porous layer 14 not covered by the LDH separator 18. This promotes the positive electrode reaction in the air electrode layer 16. From the viewpoint of space efficiency, the pressure relief valve 32 and the liquid injection port (not shown) are preferably as follows... Figure 2B As shown, it is disposed on the side of the battery casing 28 (e.g., the part that communicates with the space where the negative electrode collector tab 25 exists), or as... Figure 2D The portion shown is disposed on the upper surface of the battery casing 28 (e.g., the portion that communicates with the space where the negative electrode current collector 25 exists).

[0118] Figures 3A-3DThe diagram illustrates a zinc-air secondary battery 10” according to a third preferred embodiment of the present invention. In this embodiment, multiple air electrode / separator junctions 12 are configured such that the end face of the rigid porous layer 14 not covered by the LDH separator 18 faces downward. The zinc-air secondary battery 10” has: a positive electrode current collector 17, a positive electrode current collector terminal 34, a negative electrode current collector 35, and a negative electrode current collector terminal 36. The positive electrode current collector 17 is connected to the lower end of multiple positive electrode current collectors (in the example shown, porous metal 14a, metal mesh 14b, and porous metal layer 15 are positive electrode current collectors) via the end face of the rigid porous layer 14 not covered by the LDH separator 18. The positive electrode current collector terminal 34 is connected to the positive electrode current collector 17 and extends from the battery casing 28. The negative electrode current collector 35 is disposed in the upper remaining space 30 and is connected to the upper end of the multiple negative electrode current collectors 24. A negative current collector terminal 36 is connected to the negative current collector component 35 and extends from the battery casing 28. It should be noted that in the zinc-air secondary battery 10" according to the third preferred embodiment, the negative current collector component 35 is connected to the negative current collector terminal 36, which extends from the battery casing 28. Figures 1A-1C The components of the zinc-air secondary battery 10 shown are marked with the same symbols, and the description of the components with the same symbols in relation to the zinc-air secondary battery 10 also applies to the third preferred embodiment.

[0119] In this way, the zinc-air secondary battery 10” of this solution is configured such that the negative electrode is collected at the top of the battery and the positive electrode is collected and external air is introduced at the bottom of the battery, which is a configuration with good space efficiency. Therefore, the positive electrode current collector 17 preferably has a porous structure with ventilation. Examples of the porous structure of the positive electrode current collector 17 with ventilation can be metal mesh, metal non-woven fabric, perforated metal, etc. It is preferable to further provide a fan 38 below the battery casing 28, which is used to transmit air through the steel Air is introduced into the rigid porous layer 14 through the end face not covered by the LDH separator 18. This promotes the positive electrode reaction in the air electrode layer 16. From a space efficiency perspective, the pressure relief valve 32 and the liquid injection port 33 are preferably located on the upper surface or side of the battery casing 28. In particular, in this design, there is no positive electrode current collector structure on the upper part of the battery; therefore, there are fewer restrictions on the placement of the pressure relief valve 32 and the liquid injection port 33 on the upper surface of the battery casing 28, allowing for greater design freedom.

[0120] Figures 4A-4EThis illustration shows a zinc-air secondary battery 10”' according to a fourth preferred embodiment of the present invention. In this embodiment, multiple air electrode / separator junctions 12 are configured such that the end face of the rigid porous layer 14 not covered by the LDH separator 18 faces downward. The zinc-air secondary battery 10”' has: a positive electrode current collector 17, a positive electrode current collector terminal 34, a negative electrode current collector 35, and a negative electrode current collector terminal 36. The positive electrode current collector 17 is connected to the lower end of multiple positive electrode current collectors (in the example shown, the porous metal 14a is a positive electrode current collector) via the end face of the rigid porous layer 14 not covered by the LDH separator 18. It should be noted that... Figures 4A-4D In this configuration, the lower end of the rigid porous layer 14 floats above the bottom surface of the battery casing 28, which has the advantage of making the battery lighter. However, as... Figure 4E As shown, the rigid porous layer 14 can be configured such that its lower end extends to or near the bottom surface of the battery casing 28. In this case, there is an advantage of increased area for air to enter the pores of the rigid porous layer 14. A positive current collector terminal 34 is connected to the positive current collector 17 and extends from the battery casing 28. A negative current collector 35 is disposed in the upper remaining space 30 and connected to the upper ends of the plurality of negative current collectors 24. A negative current collector terminal 36 is connected to the negative current collector 35 and extends from the upper surface of the battery casing 28. By having the negative current collector terminal 36 extend from the upper surface of the battery casing 28, the structure in the upper remaining space 30 is simplified and current collection is easier. The negative current collector 35 is preferably a negative current collector tab extending upward from the upper ends of the plurality of negative current collectors 24, thereby enabling the plurality of negative current collector tabs to be combined and connected to a single negative current collector terminal 36. The LDH separator 18 is configured as an integrally connected elongated strip that is opposite to each of the multiple air electrode / separator joints 12 and each of the multiple negative electrode plates 20. The integrally connected elongated LDH separator 18 can be: (i) a single elongated LDH separator, or (ii) a component formed by joining adjacent ends of multiple LDH separators together using a hot-melt or other adhesive method. The elongated LDH separator 18 has a zigzag structure. It should be noted that in the case of (ii) above, bending is not actually required; the joint portion can simply be a folded shape. In the multiple divisions formed by this zigzag structure, a stack (14+16) of air electrode layers 16 and rigid porous layers 14 and negative electrode plates 20 are alternately housed, thereby separating the air electrode layers 16 and negative electrode plates 20 from each other by means of the LDH separator 18. It should be noted that in the zinc-air secondary battery 10”' according to the fourth preferred embodiment, the components are connected to each other. Figures 1A-1C The components of the zinc-air secondary battery 10 shown are marked with the same symbols, and the descriptions of the components with the same symbols in relation to the zinc-air secondary battery 10 also apply to the fourth preferred embodiment. Furthermore, Figure 4A and 4EIn the text, the rigid porous layer 14 is depicted as a porous metal 14a, but is not limited to this; other materials may be used. Figure 1A Other forms, such as the metal mesh 14b or the porous resin 14c shown.

[0121] In this way, the zinc-air secondary battery 10”” of this solution is configured such that the negative electrode current collection is performed at the top of the battery and the positive electrode current collection and external air introduction are performed at the bottom of the battery, which is a configuration with good space efficiency. Therefore, the positive electrode current collection component 17 preferably has a porous structure with ventilation. Examples of the porous structure of the positive electrode current collection component 17 with ventilation can be metal mesh, metal non-woven fabric, perforated metal, etc. It is preferable to further provide a fan 38 below the battery casing 28, which is used to transmit air through a rigid multi-layer... Air is introduced into the rigid porous layer 14 through the end face not covered by the LDH separator 18. This promotes the positive electrode reaction in the air electrode layer 16. From a space efficiency perspective, the pressure relief valve 32 and the liquid injection port (not shown) are preferably located on the upper surface or side of the battery casing 28. In particular, in this design, there is no positive electrode current collector structure on the upper part of the battery; therefore, there are fewer restrictions on the placement of the pressure relief valve 32 and the liquid injection port (not shown) on the upper surface of the battery casing 28, allowing for greater design freedom.

[0122] Furthermore, in the zinc-air secondary battery 10”' of this solution, the elongated LDH separator 18 has a tortuous structure, which eliminates or minimizes the need for complex sealing between the LDH separator 18 and the battery casing 28, thus significantly improving manufacturing efficiency. From this perspective, it is preferable to heat-seal adjacent ends of the elongated LDH separator 18 in the width direction, which sandwich the negative electrode plate 20, in a manner that closes the side end of the negative electrode plate 20. Accordingly, the portion of the elongated LDH separator 18 that houses the negative electrode plate 20 has a bag-like structure, and the electrolyte 26 is housed within this bag-like structure. This achieves an ideal seal for the bag-like structure housing the negative electrode plate 20 and the electrolyte 26, thus, as... Figure 4A and 4B The fixing portion F (e.g., formed by heat fusion) on the inner wall of the LDH separator 18 and the battery casing 28, as shown, can be done only locally, which simplifies the structure accompanied by sealing, and is advantageous in this respect. Figure 4A As shown, the long end of the elongated LDH separator 18 is preferably fixed to the inner wall of the battery casing 28. Similarly, as Figure 4B As shown, the ends of the elongated LDH separator 18 in the width direction are preferably fixed to the inner wall of the battery casing 28. The fixing of the ends of the elongated LDH separator 18 to the inner wall of the battery casing 28 can be done by any method such as hot melt, adhesive, or other fixing means; however, for the sake of ease of manufacturing, hot melt is preferred.

[0123] Figures 5A-5E This illustrates a zinc-air secondary battery 10”” according to a fifth preferred embodiment of the present invention. In this embodiment, multiple air electrode / separator junctions 12 are configured such that the end face of the rigid porous layer 14 not covered by the LDH separator 18 faces downward. The zinc-air secondary battery 10”” has: a positive electrode current collector 17, a positive electrode current collector terminal 34, a negative electrode current collector 35, and a negative electrode current collector terminal 36. The positive electrode current collector 17 is connected to the lower end of multiple positive electrode current collectors (in the example shown, the porous metal 14a is a positive electrode current collector) via the end face of the rigid porous layer 14 not covered by the LDH separator 18. It should be noted that Figures 5A-5D In this configuration, the lower end of the rigid porous layer 14 floats above the bottom surface of the battery casing 28, which has the advantage of making the battery lighter. However, as... Figure 5E As shown, the rigid porous layer 14 can be configured such that its lower end extends to or near the bottom surface of the battery casing 28. In this case, there is an advantage of increased area for air to enter the pores of the rigid porous layer 14. A positive current collector terminal 34 is connected to the positive current collector 17 and extends from the battery casing 28. A negative current collector 35 is disposed within the upper remaining space 30 and is connected to the upper ends of the plurality of negative current collectors 24. A negative current collector terminal 36 is connected to the negative current collector 35 and extends from the side of the battery casing 28. By having the negative current collector terminal 36 extend from the side of the battery casing 28, the design freedom on the upper surface of the battery casing 28 is increased, for example, as... Figure 5B As shown, the pressure relief valve 32 can also be located at the center of the upper surface of the battery casing 28. The negative electrode current collector 35 is preferably a negative electrode tab extending upwards from the upper ends of multiple negative electrode current collectors 24, thereby allowing the multiple negative electrode current collector tabs to be combined and connected to a single negative electrode current collector terminal 36. The LDH separator 18 is configured as an integrally connected strip-shaped component, facing each of the multiple air electrode / separator joints 12 and each of the multiple negative electrode plates 20. The integrally connected strip-shaped LDH separator 18 can be: (i) a single strip-shaped LDH separator, or (ii) a strip-shaped component formed by joining adjacent ends of multiple LDH separators together using a hot-melt or other adhesive method. The strip-shaped LDH separator 18 has a zigzag structure. It should be noted that in the case of (ii) above, bending is not actually necessary; the joint portion can simply be a folded-back shape. A stack (14+16) of air electrode layers 16 and rigid porous layers 14, along with a negative electrode plate 20, is alternately housed in multiple zones formed by this zigzag structure, wherein the air electrode layers 16 and the negative electrode plate 20 are separated from each other by means of an LDH separator 18. It should be noted that in the zinc-air secondary battery 10”” according to the fifth preferred embodiment, for the… Figures 1A-1CThe components of the zinc-air secondary battery 10 shown are marked with the same symbols, and the descriptions of the components with the same symbols in relation to the zinc-air secondary battery 10 also apply to the fifth preferred embodiment. Furthermore, Figure 5A and 5E In the text, the rigid porous layer 14 is depicted as a porous metal 14a, but is not limited to this; other materials may be used. Figure 1A Other forms, such as the metal mesh 14b or the porous resin 14c shown.

[0124] In this way, the zinc-air secondary battery 10” of this solution is configured such that the negative electrode current collection is performed at the top of the battery and the positive electrode current collection and external air introduction are performed at the bottom of the battery, which is a configuration with good space efficiency. Therefore, the positive electrode current collection component 17 preferably has a porous structure with ventilation. Examples of positive electrode current collection components 17 with a porous structure with ventilation can be metal mesh, metal non-woven fabric, perforated metal, etc. A fan 38 is preferably further provided below the battery casing 28, which is used to introduce air into the rigid porous layer 14 through the end face of the rigid porous layer 14 that is not covered by the LDH separator 18. Accordingly, the positive electrode reaction in the air electrode layer 16 can be promoted. From the viewpoint of space efficiency, the pressure relief valve 32 and the liquid injection port (not shown) are preferably provided on the upper surface or side of the battery casing 28. In particular, in this design, there is no positive electrode current collector structure on the upper part of the battery. Therefore, there are fewer restrictions on the position of the pressure relief valve 32 and the liquid injection port (not shown) on the upper surface of the battery casing 28, and the design freedom is high.

[0125] Furthermore, in the zinc-air secondary battery 10” of this solution, the elongated LDH separator 18 has a tortuous structure, which eliminates or minimizes the need for complex sealing between the LDH separator 18 and the battery casing 28, thus significantly improving manufacturing efficiency. From this perspective, it is preferable to heat-seal adjacent ends of the elongated LDH separator 18 in the width direction, which sandwich the negative electrode plate 20, so that the side ends of the negative electrode plate 20 are closed. Accordingly, the portion of the elongated LDH separator 18 that houses the negative electrode plate 20 has a bag-like structure, and the electrolyte 26 is housed within this bag-like structure. This achieves an ideal seal for the bag-like structure housing the negative electrode plate 20 and the electrolyte 26, thus... Figure 5A and 5B The fixing portion F (e.g., formed by heat fusion) on the inner wall of the LDH separator 18 and the battery casing 28, as shown, can be done only locally, which simplifies the structure accompanied by sealing, and is advantageous in this respect. Figure 5A As shown, the long end of the elongated LDH separator 18 is preferably fixed to the inner wall of the battery casing 28. Similarly, as Figure 5BAs shown, the ends of the elongated LDH separator 18 in the width direction are preferably fixed to the inner wall of the battery casing 28. The fixing of the ends of the elongated LDH separator 18 to the inner wall of the battery casing 28 can be done by any method such as hot melt, adhesive, or other fixing means; however, for the sake of ease of manufacturing, hot melt is preferred.

[0126] In all of the above-described first, second, third, fourth, and fifth preferred embodiments, it is preferable that, as described above, multiple air electrode / separator joints 12 and multiple negative electrode plates 20 are inserted into the battery casing 28 without gaps along the lateral direction, and the inner wall of the battery casing 28 applies pressure to the air electrode / separator joints 12 and negative electrode plates 20 in the thickness direction. Accordingly, the gap allowing zinc dendrite growth between the negative electrode plate 20 and the LDH separator 18 is minimized (preferably eliminated), thereby more effectively preventing zinc dendrite extension.

[0127] Air electrode / separator assembly (excluding the rigid porous layer)

[0128] Figure 9 The diagram shows an air electrode / septum assembly employing an LDH separator, and is a preferred embodiment of the portion other than the rigid porous layer. Figure 9 The air electrode / separator junction 110 shown includes an LDH separator 112 and an air electrode layer 116. Preferably, an interface layer 114 is provided between the LDH separator 112 and the air electrode layer 116, the interface layer 114 comprising a hydroxide ion-conducting material and a conductive material. However, as long as a desired low-resistance bond can be achieved between the LDH separator 112 and the air electrode layer 116, the interface layer 114 may be omitted. The air electrode layer 116 includes at least an outermost catalyst layer 120. Preferably, the air electrode layer 116 has an inner catalyst layer 118 between the interface layer 114 and the outermost catalyst layer 120; however, it may also be like... Figure 10 The air electrode / separator junction 110' shown does not have an inner catalyst layer 118. The outermost catalyst layer 120 is composed of a porous current collector 120a and an LDH 120b covering its surface. Furthermore, the hydroxide ion-conducting material included in the interface layer 114 preferably has the morphology of multiple plate-like particles, such as... Figure 11 As shown in the schematic diagram, multiple plate-shaped particles 113 are bonded to the main surface of the LDH separator 112 perpendicularly or obliquely. According to this configuration, when a metal-air secondary battery is manufactured, it can exhibit excellent charge-discharge performance even if the electrolyte is not present in the air electrode layer 116.

[0129] That is, as described above, metal-air secondary batteries using LDH separators have the excellent advantage of simultaneously preventing short circuits between the positive and negative electrodes caused by metal dendrites and the introduction of carbon dioxide. Furthermore, they also have the advantage of suppressing the evaporation of moisture contained in the electrolyte due to the density of the LDH separator. However, since the LDH separator prevents electrolyte from permeating to the air electrode, there is no electrolyte in the air electrode layer. Therefore, compared to zinc-air secondary batteries using conventional separators (such as porous polymer separators) that allow electrolyte permeation to the air electrode, hydroxide ion conductivity is often reduced, leading to decreased charge-discharge performance. In this regard, the air electrode / separator junction 110 effectively eliminates the above-mentioned problems.

[0130] The exact details of its mechanism may not be fully understood, but it is believed to be as follows: The outermost catalyst layer 120 contains a porous current collector 120a, thus functioning as a layer responsible for both current collection and gas diffusion in the form of a gas diffusion electrode. However, by covering the surface of the porous current collector 120a with LDH120b, in addition to the aforementioned functions, it also possesses catalytic performance and hydroxide ion conductivity, thereby ensuring a larger reactive area. This is because LDH120b, i.e., layered double hydroxide, is a hydroxide ion conducting material and can also function as an air electrode catalyst. It is believed that a three-phase interface exists throughout the entire region of the outermost catalyst layer 120, consisting of an ion-conducting phase (LDH 120b), an electron-conducting phase (porous current collector 120a), and a gas phase (air). Therefore, a three-phase interface exists not only at the interface between the LDH separator 112 and the air electrode layer 116 (interface layer 114), but also within the air electrode layer 116 itself. This allows for more efficient acceptance and donation of hydroxide ions, which facilitates the battery reaction, with a larger surface area (i.e., reduced reaction resistance). Furthermore, it is believed that because the interface layer 114 contains both hydroxide ion-conducting and conductive materials, and the plate-like particles 113 of the hydroxide ion-conducting material contained in the interface layer 114 are perpendicularly or obliquely bonded to the main surface of the LDH separator, the acceptance and donation of hydroxide ions between the air electrode layer 116 and the LDH separator 112 proceeds extremely smoothly (i.e., reduced reaction resistance). In particular, the plate-like particles 113 of hydroxide ion-conducting materials such as LDH have the characteristic of conducting hydroxide ions in the plate-plane direction (in the case of LDH, the (003) crystal plane direction). Therefore, it is believed that by combining the plate-like particles 113 perpendicularly or obliquely with the main surface of the LDH separator 112, the interfacial resistance between the air electrode layer 116 and the LDH separator 112 is reduced. It is believed that, in this way, the many functions of the interface layer 114 and the outermost catalyst layer 120 are well combined, thereby possessing the advantages of using the LDH separator 112, and achieving excellent charge-discharge performance.

[0131] Interface layer 114 comprises a hydroxide ion-conducting material and a conductive material. The hydroxide ion-conducting material contained in interface layer 114 has the morphology of multiple plate-like particles 113, such as... Figure 11 Structurally, multiple plate-like particles 113 are bonded to the main surface of the LDH separator 112 perpendicularly or obliquely. The interface layer 114 contains a hydroxide ion-conducting material that is hydroxide ion-conducting and has a plate-like particle morphology; it is not particularly limited, but preferably LDH and / or LDH-like compounds. In particular, if the microstructure of the surface of the LDH separator 112 fabricated according to known methods is observed, such as... Figure 11 As shown, a typical configuration involves the LDH plate-like particles 113 being vertically or obliquely bonded to the main surface of the LDH separator 112. In this invention, the plate-like particles (hydroxide ion-conducting material) and the conductive material in such an orientation state exist between the LDH separator 112 and the air electrode layer 116, thereby significantly reducing the interfacial resistance. Therefore, as the hydroxide ion-conducting material included in the interface layer 114, a material of the same type as the LDH and / or LDH-like compound included in the LDH separator 112 is used, thereby allowing the LDH plate-like particles 113 for constituting the interface layer 114 to be prepared simultaneously during the fabrication of the LDH separator 112. On the other hand, the conductive material included in the interface layer 114 preferably comprises a carbon material. Preferred examples of carbon materials include carbon black, graphite, carbon nanotubes, graphene, reduced graphene oxide, and any combination thereof, but are not limited to these; various other carbon materials may also be used. The interface layer 114 can be fabricated by coating a slurry or solution containing carbon material (e.g., carbon ink such as graphene ink) onto the surface of the LDH separator 112 where plate-shaped particles 113 are vertically or obliquely bonded, thereby fabricating the interface layer 114. Alternatively, if an internal catalyst layer 118 is provided, the internal catalyst layer 118 and the LDH separator 112 can be tightly bonded together, allowing the plate-shaped particles 113 on the surface of the LDH separator 112 to enter the internal catalyst layer 118 to form the interface layer 114. In this case, the portion of the plate-shaped particles 113 that enters the internal catalyst layer 118 constitutes the interface layer 114.

[0132] The outermost catalyst layer 120 contained in the air electrode layer 116 is composed of a porous current collector 120a and an LDH 120b covering its surface. The porous current collector 120a can be made of a conductive material with gas diffusion properties, and is not particularly limited, but is preferably made of at least one material selected from the group consisting of carbon, nickel, stainless steel and titanium, and more preferably carbon. Specific examples of the porous current collector 120a include carbon paper, nickel foam, stainless steel nonwoven fabric and any combination thereof, with carbon paper being preferred. Commercially available porous materials can be used as the current collector. From the viewpoint of ensuring a wider reaction region, i.e., a three-phase interface consisting of the ion-conducting phase (LDH 120b), the electron-conducting phase (porous current collector 120a), and the gas phase (air), the thickness of the porous current collector 120a is preferably 0.1 to 1 mm, more preferably 0.1 to 0.5 mm, and even more preferably 0.1 to 0.3 mm. Furthermore, the porosity of the outermost catalyst layer 120 is preferably 70% or more, more preferably 70-95%. Especially in the case of carbon paper, 70-90% is further preferred, and particularly preferably 75-85%. With the above porosity, excellent gas diffusion is ensured, and a wider reaction zone is also ensured. In addition, because there are many pore spaces, blockage by generated water is less likely. The porosity can be measured using a mercury injection method.

[0133] It is known that the LDH120b contained in the outermost catalyst layer 120 possesses at least one of the properties of catalytic performance and hydroxide ion conductivity. Therefore, the composition of LDH120b is not particularly limited, but the preferred basic composition is of the general formula: M 2+ 1-x M 3+ x (OH)2A n- x / n ·mH2O (where M) 2+ M is at least one or more divalent cations. 3+ A is at least one trivalent cation. n- For anion with an n-valence, where n is an integer greater than or equal to 1, x is between 0.1 and 0.4, and m is any real number. In the above general formula, M 2+ It can be any divalent cation; as a preferred example, Ni can be cited. 2+ Mg 2+ Ca 2+ Mn 2+ Fe 2+ Co 2+ Cu 2+ Zn 2+ M 3+ It can be any trivalent cation; as a preferred example, Fe can be cited. 3+ V3+ Al 3+ Co 3+ Cr 3+ In 3+ In particular, to ensure that LDH120b possesses both catalytic performance and hydroxide ion conductivity, M is preferred. 2+ and M 3+ All are transition metal ions. From this perspective, M is a more preferred option. 2+ For Ni 2+ Mn 2+ Fe 2+ Co 2+ Cu 2+ Isovalent transition metal ions, especially Ni 2+ On the other hand, a more preferred M 3+ For Fe 3+ V 3+ Co 3+ Cr 3+ Trivalent transition metal ions, especially Fe 3+ V 3+ and / or Co 3 + In this case, M 2+ A portion can be made from Mg 2+ Ca 2+ Zn 2+ Replacement with metal ions other than transition metals, and M 3+ A portion can be made by Al 3+ In 3+ Replacement with metal ions other than transition metals. A n- It can be any anion; as a preferred example, NO can be cited. 3- CO3 2- SO4 2- OH - Cl - I - ,Br - F - NO is preferred. 3- and / or CO3 2- Therefore, the preferred general formula is: M 2+ Contains Ni 2+ M 3+ Contains Fe 3+ A n- Contains NO 3- and / or CO3 2-n is an integer greater than or equal to 1, preferably 1 to 3. x is between 0.1 and 0.4, preferably 0.2 to 0.35. m is any real number. More specifically, m is greater than or equal to 0, typically a real number or integer greater than or equal to 1.

[0134] LDH120b preferably has the morphology of multiple LDH plate-like particles, which are perpendicularly or obliquely bonded to the surface of the porous current collector. Furthermore, it is preferable that the multiple LDH plate-like particles are interconnected in the outermost catalyst layer 120. With such a configuration, the reaction resistance can be reduced. Alternatively, the above configuration can be achieved by immersing the porous current collector 120a in an LDH feedstock solution using a known method to perform hydrothermal synthesis of the LDH particles.

[0135] LDH120b can be a mixture of two or more types of LDH with different compositions. In this case, from the viewpoint of ensuring the load-bearing strength relative to the substrate, it is preferable that the particle size distributions of the two or more types of LDH particles are different from each other. From the viewpoint of promoting oxygen diffusion into the porous current collector 120a and ensuring a large loading of LDH, it is preferable that the LDH plate-like particles with a larger average particle size are perpendicular or inclined to the surface of the porous current collector 120a.

[0136] In the outermost catalyst layer 120, LDH120b functions as an air electrode catalyst and / or a hydroxide ion-conducting material. However, in addition to LDH120b, the outermost catalyst layer 120 may further contain an air electrode catalyst and / or a hydroxide ion-conducting material. Examples of catalysts other than LDH include metal oxides, metal nanoparticles, carbon materials, and any combination thereof. Furthermore, the outermost catalyst layer 120 preferably contains a material capable of adjusting the moisture content. In this regard, LDH120b itself functions as a material capable of adjusting the moisture content; however, other examples include zeolites, calcium hydroxide, and combinations thereof.

[0137] The outermost catalyst layer 120 can be manufactured by using a known method to precipitate LDH120b on the surface of the porous current collector 120a via hydrothermal synthesis, without any particular limitation. For example, the outermost catalyst layer 120 can be manufactured as follows: (1) Prepare a porous current collector 120a; (2) Coat the porous current collector 120a with an iron oxide solution and dry it to form an iron oxide layer; (3) Impregnate the porous substrate with a solution containing nickel ions (Ni... 2+ (4) The porous substrate is subjected to hydrothermal treatment in the raw material aqueous solution to form LDH120b (in this case, Ni-Fe-LDH) on the surface of the porous current collector 120a.

[0138] The air electrode layer 116 preferably also has an inner catalyst layer 118 between the outermost catalyst layer 120 and the interface layer 114. In this case, the inner catalyst layer 118 is preferably filled with a mixture 118a comprising a hydroxide ion-conducting material, a conductive material, an organic polymer, and an air electrode catalyst. The hydroxide ion-conducting material can be the same material as the air electrode catalyst; examples of such materials include LDH containing transition metals (e.g., Ni-Fe-LDH, Co-Fe-LDH, and Ni-Fe-V-LDH). On the other hand, examples of hydroxide ion-conducting materials that do not also serve as air electrode catalysts include Mg-Al-LDH. Furthermore, the conductive material can be the same material as the air electrode catalyst; examples of such materials include carbon materials, metal nanoparticles, nitrides such as TiN, and LaSr3Fe3O4. 10 wait.

[0139] The hydroxide ion-conducting material contained in the internal catalyst layer 118 can be any material with hydroxide ion conductivity, and is not particularly limited, but is preferably LDH and / or LDH-like compounds. The composition of LDH is not particularly limited, but the preferred basic composition is of the general formula: M 2+ 1-x M 3+ x (OH)2A n- x / n ·mH2O (where M) 2+ M is at least one or more divalent cations. 3+ A is at least one trivalent cation. n- For anion with an n-valence, where n is an integer greater than or equal to 1, x is between 0.1 and 0.4, and m is any real number. In the above general formula, M 2+ It can be any divalent cation; as a preferred example, Ni can be cited. 2+ Mg 2+ Ca 2+ Mn 2+ Fe 2+ Co 2 + Cu 2+ Zn 2+ M 3+ It can be any trivalent cation; as a preferred example, Fe can be cited. 3+ V 3+ Al 3+ Co 3+ Cr 3+ In 3 + In particular, to ensure that LDH possesses both catalytic performance and hydroxide ion conductivity, M is preferred.2+ and M 3+ All are transition metal ions. From this perspective, M is a more preferred option. 2+ For Ni 2+ Mn 2+ Fe 2+ Co 2+ Cu 2+ Isovalent transition metal ions, especially Ni 2+ On the other hand, the more preferred M 3+ For Fe 3+ V 3+ Co 3+ Cr 3+ Trivalent transition metal ions, especially Fe 3+ V 3 + and / or Co 3+ In this case, M 2+ A portion can be made from Mg 2+ Ca 2+ Zn 2+ Replacement with metal ions other than transition metals, and M 3+ A portion can be made by Al 3+ In 3+ Replacement with metal ions other than transition metals. A n- It can be any anion; as a preferred example, NO can be cited. 3- CO3 2- SO4 2- OH - Cl - I - ,Br - F - NO is preferred. 3- and / or CO3 2- Therefore, the preferred general formula is: M 2+ Contains Ni 2+ M 3+ Contains Fe 3+ A n- Contains NO 3- and / or CO3 2- n is an integer greater than or equal to 1, preferably 1 to 3. x is between 0.1 and 0.4, preferably 0.2 to 0.35. m is any real number. More specifically, m is greater than or equal to 0, typically a real number or integer greater than or equal to 1.

[0140] The conductive material contained in the internal catalyst layer 118 is preferably at least one selected from the group consisting of conductive ceramics and carbon materials. In particular, examples of conductive ceramics include LaNiO3 and LaSr3Fe3O4. 10 Examples of carbon materials include: carbon black, graphite, carbon nanotubes, graphene, reduced graphene oxide, and any combination thereof, but are not limited to these; various other carbon materials can also be used.

[0141] The air electrode catalyst included in the internal catalyst layer 118 is preferably at least one selected from the group consisting of LDH and other metal hydroxides, metal oxides, metal nanoparticles, and carbon materials, and more preferably at least one selected from the group consisting of LDH, metal oxides, metal nanoparticles, and carbon materials. For LDH, as described above regarding hydroxide ion-conducting materials, it is particularly ideal to possess both the functions of an air electrode catalyst and a hydroxide ion-conducting material. Examples of metal hydroxides include Ni-Fe-OH, Ni-Co-OH, and any combination thereof, which may further contain a third metal element. Examples of metal oxides include Co3O4, LaNiO3, and LaSr3Fe3O4. 10 And any combination thereof. Examples of metal nanoparticles (typically metal particles with a particle size of 2–30 nm) include Pt, Ni-Fe alloys, etc. Examples of carbon materials, as mentioned above, include carbon black, graphite, carbon nanotubes, graphene, reduced graphene oxide, and any combination thereof, but are not limited to these; various other carbon materials can also be used. From the viewpoint of improving the catalytic performance of carbon materials, carbon materials preferably also contain metal elements and / or other elements such as nitrogen, boron, phosphorus, and sulfur.

[0142] The organic polymer contained in the internal catalyst layer 118 can be a known adhesive resin. Examples of organic polymers include butyral resins, vinyl alcohol resins, cellulose resins, vinyl alcohol acetal resins, fluorinated resins, etc., with butyral resins and fluorinated resins being preferred.

[0143] For the inner catalyst layer 118, it is desirable that its porosity is lower than that of the outermost catalyst layer 120, so as to efficiently facilitate the donation and acceptance of hydroxide ions with the LDH separator 112. Specifically, the porosity of the inner catalyst layer 118 is preferably 30-60%, more preferably 35-60%, and even more preferably 40-55%. For the same reason, the average pore size of the inner catalyst layer is preferably 5 μm or less, more preferably 0.5-4 μm, and even more preferably 1-3 μm. The porosity and average pore diameter of the internal catalyst layer 118 can be determined as follows: a) The LDH separator is polished using a cross-section polisher (CP); b) Cross-sectional images of the internal catalyst layer are obtained in two fields of view at a magnification of 10,000 using SEM (scanning electron microscope); c) Based on the image data of the obtained cross-sectional images, the images are binarized using image analysis software (e.g., Image-J); d) The area of ​​each pore is calculated for each of the two fields of view, and the porosity and pore diameter of each pore are calculated. The average value of these values ​​is taken as the porosity and average pore diameter of the internal catalyst layer. It should be noted that the pore diameter can be calculated as follows: after converting the length of each pixel in the image to the actual size, assuming that each pore is a perfect circle, divide the area of ​​each pore obtained through image analysis by pi, multiply the square root by 2, and thus calculate the pore diameter; the porosity can be calculated as follows: divide the number of pixels belonging to pores by the number of pixels in the total area, multiply by 100, and thus calculate the porosity.

[0144] The internal catalyst layer 118 can be manufactured by preparing a paste comprising a hydroxide ion-conducting material, a conductive material, an organic polymer, and an air electrode catalyst, and then coating this paste onto the surface of the LDH separator 112, thereby creating the internal catalyst layer 118. The paste can be prepared by appropriately adding an organic polymer (adhesive resin) and an organic solvent to a mixture of the hydroxide ion-conducting material, the conductive material, and the air electrode catalyst, using a known mixing mill such as a three-roll mill. Preferred examples of organic solvents include: butyl carbitol, terpineol, and other alcohols; acetate ester solvents such as butyl acetate; and N-methyl-2-pyrrolidone. Alternatively, the paste can be applied to the LDH separator 112 by printing. This printing can be performed using various known printing methods; however, screen printing is preferred.

[0145] However, air polar layer 116 can be like Figure 10 The air electrode / separator assembly 110' shown does not have an internal catalyst layer 118. In this case, it is desirable to reduce the contact resistance by uniformly pressurizing the air electrode layer 116 and the LDH separator 112 in a manner that tightly seals the outermost catalyst layer 120 and the interface layer 114.

[0146] As described above, the air electrode / separator junction 110 is preferably used in a metal-air secondary battery. That is, according to a preferred embodiment of the invention, a metal-air secondary battery is provided, comprising: an air electrode / separator junction 110, a metal negative electrode, and an electrolyte, the electrolyte being separated from the air electrode layer 116 by means of an LDH separator 112. A zinc-air secondary battery using a zinc electrode as the metal negative electrode is particularly preferred. Alternatively, a lithium-air secondary battery using a lithium electrode as the metal negative electrode may also be used.

[0147] LDH partition

[0148] The preferred embodiment of the LDH separator 18 of the present invention will be described below. It should be noted that the following description assumes a zinc-air secondary battery; however, the LDH separator 18 of this embodiment can also be applied to other metal-air secondary batteries such as lithium-air secondary batteries. As described above, the LDH separator 18 of this embodiment... Figure 8 Structurally shown, it includes: a porous substrate 18a and a hydroxide ion-conducting layered compound 18b. It should be noted that... Figure 8 The region of the hydroxide ion-conducting layered compound 18b is depicted as not connected between the upper and lower surfaces of the LDH separator 18 because it is depicted in two dimensions in cross-sectional form. However, considering the depth in three dimensions, the region of the hydroxide ion-conducting layered compound 18b is connected between the upper and lower surfaces of the LDH separator 18, thereby ensuring the hydroxide ion conductivity of the LDH separator 18. The porous substrate 18a is made of a polymer material, and the hydroxide ion-conducting layered compound 18b seals the pores of the porous substrate 18a. However, the pores of the porous substrate 18a do not need to be completely sealed; slight residual pores P may remain. By highly densifying the pores of the polymer porous substrate 18a by sealing them with the hydroxide ion-conducting layered compound 18b, an LDH separator 18 that can more effectively suppress short circuits caused by zinc dendrites can be provided.

[0149] Furthermore, the LDH separator 18 of this solution possesses the desired ionic conductivity required for a separator due to the hydroxide ion-conducting layered compound 18b, and also exhibits excellent flexibility and strength. This is because the polymer porous substrate 18a contained in the LDH separator 18 itself possesses both flexibility and strength. That is, with the pores of the polymer porous substrate 18a fully sealed by the hydroxide ion-conducting layered compound 18b, the LDH separator 18 becomes dense. Therefore, it is a seamlessly integrated material that is highly composite of the polymer porous substrate 18a and the hydroxide ion-conducting layered compound 18b. Thus, it can be said that the rigidity and brittleness caused by the hydroxide ion-conducting layered compound 18b, which is a ceramic material, are offset or mitigated by the flexibility and strength of the polymer porous substrate 18a.

[0150] The LDH separator 18 of this design is expected to have very few residual pores P (pores not sealed by the hydroxide ion-conducting layered compound 18b). Because of the residual pores P, the LDH separator 18 has an average porosity of, for example, 0.03% or more and less than 1.0%, preferably 0.05% or more and less than 0.95%, more preferably 0.05% or more and less than 0.9%, further preferably 0.05% to 0.8%, and most preferably 0.05% to 0.5%. If the average porosity is within the above range, the pores of the polymer porous substrate 18a are sufficiently sealed by the hydroxide ion-conducting layered compound 18b, resulting in extremely high compactness. Therefore, short circuits caused by zinc dendrites can be suppressed more effectively. Furthermore, a significantly higher ion conductivity can be achieved, and the LDH separator 18 can fully function as a hydroxide ion-conducting compact separator. The average porosity can be determined as follows: a) The LDH septum is polished using a cross-section polisher (CP); b) Cross-sectional images of the functional layer are obtained in two fields of view at a magnification of 50,000 using FE-SEM (field emission scanning electron microscope); c) Based on the image data of the obtained cross-sectional images, the porosity of each of the two fields of view is calculated using image inspection software (e.g., HDevelop, MVTec Software), and the average porosity is obtained.

[0151] The LDH separator 18 is a separator containing a hydroxide ion-conducting layered compound 18b. When assembled in a zinc secondary battery, it separates the positive and negative electrode plates in a manner that enables hydroxide ion conduction. That is, the LDH separator 18 functions as a dense separator for hydroxide ion conduction. Therefore, the LDH separator 18 is impermeable to air and / or impermeable to water. Accordingly, the LDH separator 18 is preferably densified to a degree that makes it impermeable to air and / or impermeable to water. It should be noted that "impermeable to air" in this specification means, as described in Patent Documents 2-4, that 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 helium gas are observed from the other side. Furthermore, "impermeable to water" in this specification means, as described in Patent Documents 2-4, that water in contact with one side of the test object does not permeate to the other side. In other words, the LDH separator 18's impermeability to air and / or water means that it possesses a high degree of density, preventing the passage of gas or water, and is not a porous membrane or other porous material that is permeable to water or air. Therefore, the LDH separator 18, due to its hydroxide ion conductivity, allows only hydroxide ions to selectively pass through, thus functioning as a battery separator. Consequently, it becomes a highly effective configuration for preventing short circuits between the positive and negative electrodes caused by the physical prevention of separator penetration due to zinc dendrites generated during charging. Because the LDH separator 18 has hydroxide ion conductivity, the required hydroxide ions can move efficiently between the positive and negative electrodes, thereby enabling the charging and discharging reactions in both electrodes.

[0152] The He permeability per unit area of ​​the LDH separator 18 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 Zn permeation (typically zinc ions or zincate ions) in the electrolyte. In principle, the separator of this design significantly suppresses Zn permeation, thereby effectively suppressing the growth of zinc dendrites when used in zinc secondary batteries. The He permeability is determined by the following steps: supplying He gas to one side of the separator to allow the He gas to pass through the separator, and calculating the He permeability to evaluate the compactness of the hydroxide ion transport-induced dense 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 passes, according to the formula F / (P×S). By evaluating gas permeability using He gas in this way, it is possible to assess whether an extremely high level of compactness exists. Consequently, it is possible to effectively evaluate a high level of compactness that minimizes the permeability of substances other than hydroxide ions (especially Zn, which causes zinc dendrite growth) (allowing only trace amounts to permeate). This is because He gas has the smallest constituent unit among the diverse range of 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, hydrogen gas is composed of H2 molecules; therefore, as a gas constituent unit, He atom monomers are even smaller. Furthermore, H2 gas is a flammable gas, making it dangerous. Moreover, by employing an index such as He gas permeability defined by the above formula, an objective evaluation of compactness can be easily performed regardless of variations in sample size and measurement conditions. This allows for a simple, safe, and effective evaluation of whether a separator possesses sufficiently high compactness suitable for zinc secondary batteries. It is preferable to measure the He permeability in the order shown in Patent Documents 2 and 4.

[0153] In the LDH separator 18, a hydroxide ion-conducting layered compound 18b, acting as LDH and / or LDH-like compounds, seals the pores of the porous substrate 18a. It is generally known that LDH consists of multiple hydroxide base layers and intermediate layers between these base layers. The hydroxide base layers are primarily composed of metal elements (typically metal ions) and OH groups. The intermediate layers of LDH consist of anions and H₂O. The anions are ions with a valence of 1 or higher, preferably ions with a valence of 1 or 2. Preferably, the anions in the LDH include OH groups. - and / or CO3 2- In addition, LDH has excellent ionic conductivity due to its inherent properties.

[0154] Typically, it is known that LDH is based on the fundamental 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 substance represented by an anion with an n-valence (where n is an integer greater than or equal to 1, x is between 0.1 and 0.4, and m is greater than or equal to 0) is an n-valent anion. In the above basic formula, M... 2+ It can be any divalent cation; as a preferred example, Mg can be cited. 2+ Ca 2+ and Zn 2+ More preferably Mg 2+ M 3+ It can be any trivalent cation; as a preferred example, Al can be cited. 3+ or Cr 3+ Al is preferred. 3+ A n- It can be any anion; as a preferred example, OH- - and CO3 2- Therefore, in the above basic formula, M is preferably... 2+ Contains Mg 2+ M 3+ Includes Al 3+ A n- Contains OH - and / or CO3 2- n is an integer greater than or equal to 1, preferably 1 or 2. x is 0.1 to 0.4, preferably 0.2 to 0.35. m is any number representing the number of moles of water, greater than or equal to 0, typically a real number greater than 0 or 1. However, the above basic composition is merely a formula representing the "basic composition" of LDH in a typical way, and the constituent ions can be appropriately substituted. For example, in the above basic composition, M can be replaced by a cation with a valence of 4 or higher. 3+ Partial or complete substitution can be performed, in which case the anion A in the above general formula can also be appropriately changed. n- The coefficient x / n.

[0155] For example, the hydroxide base layer of an LDH can contain Ni, Al, Ti, and OH groups. The intermediate layer, as described above, consists of anions and H₂O. The alternating stacked structure of the hydroxide base layer and intermediate layer is essentially the same as the commonly known alternating stacked structure of LDH. However, the LDH of this scheme has its hydroxide base layer composed of specified elements or ions including Ni, Al, Ti, and OH groups, thus exhibiting excellent alkali resistance. The reason for this may not be certain, but for the LDH of this scheme, it is believed that the reason is that Al, which was previously thought to be easily soluble in alkaline solutions, is difficult to dissolve in alkaline solutions due to a certain interaction with Ni and Ti. Even so, the LDH of this scheme can still exhibit high ionic conductivity suitable for use as a separator in alkaline secondary batteries. The Ni in the LDH can be in the form of nickel ions. Regarding nickel ions in LDH, Ni is typically considered to be... 2+ However, it can also be Ni 3+ Nickel ions of other valences are also possible, therefore, there are no particular limitations. Al in LDH can take the form of aluminum ions. Regarding aluminum ions in LDH, Al is considered to be typical. 3+ However, it can also have other valences, so there are no particular limitations. Ti in LDH can take the form of titanium ions. Regarding titanium ions in LDH, Ti is considered to be typical. 4+ However, it can also be used for Ti 3+ Titanium ions of other valences are not particularly limited. The hydroxide base layer may contain Ni, Al, Ti, and OH groups, or may contain other elements or ions. However, it is preferable that the hydroxide base layer contains Ni, Al, Ti, and OH groups as the main components. That is, it is preferable that the hydroxide base layer mainly contains Ni, Al, Ti, and OH groups. Therefore, a typical design for the hydroxide base layer is: composed of Ni, Al, Ti, OH groups and unavoidable impurities as appropriate. Unavoidable impurities are any elements that may inevitably be mixed in during the manufacturing process, for example, elements that may originate from raw materials or substrates and be mixed into the LDH. As mentioned above, the valences of Ni, Al, and Ti are not necessarily determined; therefore, it is impractical or impossible to strictly specify the LDH using a general formula. It is assumed that the hydroxide base layer is mainly composed of Ni... 2+ Al 3+ Ti 4+ In the case of OH groups, the basic composition of the corresponding LDH can be represented by the general formula: Ni 2+ 1-x-y Al 3+ x Ti 4+ y (OH)2A n- (x+2y) / n ·mH2O (where A) n-The anion is an n-valent anion, where n is an integer greater than or equal to 1, preferably 1 or 2, 0 < x < 1, preferably 0.01 ≤ x ≤ 0.5, 0 < y < 1, preferably 0.01 ≤ y ≤ 0.5, 0 < x + y < 1, and m is greater than or equal to 0, typically a real number greater than 0 or greater than 1. However, the above general formula should be understood as only the "basic composition," and should be understood as: Ni 2+ Al 3+ Ti 4+ Elements can be replaced by other elements or ions (including elements or ions of the same element with other valences, and elements or ions that may inevitably be mixed in during the preparation process) to a degree that does not impair the basic properties of LDH.

[0156] LDH-like compounds are hydroxides and / or oxides with a layered crystalline structure that, while perhaps not strictly LDH, resemble LDH. They preferably contain Mg and at least one element selected from the group consisting of Ti, Y, and Al. By using a layered crystalline hydroxide and / or oxide containing at least Mg and Ti—that is, an LDH-like compound—instead of conventional LDH as the hydroxide ion-conducting material, a hydroxide ion-conducting barrier with excellent alkali resistance and the ability to more effectively suppress short circuits caused by zinc dendrites can be provided. Therefore, preferred LDH-like compounds are layered crystalline hydroxides and / or oxides containing Mg and at least one element selected from the group consisting of Ti, Y, and Al. Typical LDH-like compounds are composite hydroxides and / or composite oxides of Mg, Ti, Y (if desired), and Al (if desired), with composite hydroxides and / or composite oxides of Mg, Ti, Y, and Al being particularly preferred. These elements can be substituted with other elements or ions to the extent that the fundamental properties of the LDH-like compound are not compromised; however, the LDH-like compound preferably does not contain Ni.

[0157] LDH-like compounds can be identified using X-ray diffraction. Specifically, when X-ray diffraction is performed on the surface of an LDH separator, peaks originating from LDH-like compounds 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 regard, 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 LDH-like compounds 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.

[0158] The atomic ratio of Mg / (Mg+Ti+Y+Al) in the LDH-like compound, as determined by energy dispersive X-ray diffraction (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 LDH-like compounds generally have different compositional ratios (atomic ratios) than conventional LDH. It should be noted that EDS analysis is preferably performed using an EDS analysis apparatus (e.g., X-act, manufactured by Oxford Instruments) as follows: 1) Acquire images at an accelerating voltage of 20 kV and a magnification of 5,000x; 2) Perform 3-point analysis with approximately 5 μm intervals in point analysis mode; 3) Repeat steps 1) and 2) once more; 4) Calculate the average value of the total 6 points.

[0159] As described above, the LDH separator 18 comprises a hydroxide ion-conducting layered compound 18b and a porous substrate 18a (typically composed of a porous substrate 18a and the hydroxide ion-conducting layered compound 18b). In the LDH separator 18, the LDH seals the pores of the porous substrate, thereby giving it hydroxide ion conductivity and air impermeability (thus enabling it to function as an LDH separator exhibiting hydroxide ion conductivity). The hydroxide ion-conducting layered compound 18b is particularly preferably embedded throughout the entire thickness direction of the polymer porous substrate 18a. The thickness of the LDH separator is preferably 3–80 μm, more preferably 3–60 μm, and even more preferably 3–40 μm.

[0160] The porous substrate 18a is made of a polymer material. The polymer porous substrate 18a has the following advantages: 1) it is flexible (therefore, even when thinned, it is not prone to cracking); 2) it easily increases porosity; 3) it easily increases conductivity (because although porosity is increased, the thickness can be reduced); 4) it is easy to manufacture and handle. Furthermore, it has the following advantages: 5) by fully utilizing the flexibility of 1) above, the LDH separator containing the porous substrate made of polymer material can be easily bent or sealed. Preferred examples of polymer materials include polystyrene, polyethersulfone, polypropylene, epoxy resin, polyphenylene sulfide, fluoropolymers (tetrafluoroethylene resin: PTFE, etc.), cellulose, nylon, polyethylene, and any combination thereof. From the viewpoint of thermoplastic resins suitable for heat pressing, more preferred examples include: polystyrene, polyethersulfone, polypropylene, epoxy resin, polyphenylene sulfide, fluoropolymers (tetrafluoroethylene resin: PTFE, etc.), nylon, polyethylene, and any combination thereof. All of the aforementioned preferred materials exhibit resistance to battery electrolytes, i.e., alkali resistance. Considering excellent resistance to hot water, acids, and alkalis, as well as low cost, polypropylene, polyethylene, and other polyolefins 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 a hydroxide ion-conducting layered compound is embedded throughout the entire thickness direction of the porous substrate (for example, most or almost all of the pores inside the porous substrate are filled with the hydroxide ion-conducting layered compound). As such a polymeric porous substrate, a commercially available polymeric microporous membrane is preferably used.

[0161] The LDH separator of this scheme can be manufactured as follows: (i) using a porous polymer substrate, a composite material containing a hydroxide ion-conducting layered compound is produced according to a known method (see, for example, Patent Documents 1-4); (ii) the composite material containing the hydroxide ion-conducting layered compound is pressed. 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 sufficiently sealed with the hydroxide ion-conducting layered compound; in this regard, it is preferable to perform the pressing while heating. As the temperature for sufficient softening, for example, in the case of polypropylene or polyethylene, heating is preferably performed at 60-200°C. By performing pressing such as roll pressing within such a temperature range, the average porosity caused by residual pores in the LDH separator can be significantly reduced. As a result, the LDH separator can be made extremely dense, thus further effectively suppressing short circuits caused by zinc dendrites. During the rolling process, the morphology of residual pores can be controlled by appropriately adjusting the roll gap and roll temperature, thereby obtaining LDH partitions with the desired density or average porosity.

[0162] There is no particular limitation on the manufacturing method of the composite material containing hydroxide ion-conducting layered compound (i.e., coarse LDH separator) before pressing. It can be manufactured by appropriately modifying the conditions of known manufacturing methods of functional layers and composite materials containing LDH (i.e., LDH separators) (see, for example, Patent Documents 1-4). For example, the functional layer and composite material containing hydroxide ion-conducting layered compound (i.e., LDH separator) can be manufactured as follows: (1) Prepare a porous substrate; (2) Apply titanium oxide sol or a mixture of alumina and titanium dioxide sol to the porous substrate and perform heat treatment, thereby forming a titanium oxide layer or an alumina-titanium dioxide layer; (3) Impregnate the porous substrate with a solution containing nickel ions (Ni 2+ (3) In the raw material aqueous solution of urea; (4) The porous substrate is subjected to hydrothermal treatment in the raw material aqueous solution to form a functional layer containing hydroxide ion-conducting layered compound on and / or in the porous substrate. In particular, in the above step (2), by forming a titanium oxide layer or an alumina-titanium dioxide layer in the porous substrate, not only can the raw material of hydroxide ion-conducting layered compound be provided, but it can also be used as the starting point for the crystal growth of hydroxide ion-conducting layered compound, so that a highly dense functional layer containing hydroxide ion-conducting layered compound is uniformly formed in the porous substrate. In addition, urea is present in the above step (3), and ammonia is generated in the solution by the hydrolysis of urea, so that the pH value rises and the coexisting metal ions form hydroxide, thereby obtaining hydroxide ion-conducting layered compound. In addition, the hydrolysis is accompanied by the generation of carbon dioxide, so a hydroxide ion-conducting layered compound with carbonate ion as anion can be obtained.

[0163] In particular, when fabricating a composite material (i.e., an LDH separator) in which the porous substrate is made of a polymer material and the functional layer is embedded throughout the entire thickness direction of the porous substrate, it is preferable to apply the mixed sol of alumina and titanium dioxide to the substrate as described in (2) by a method that allows the mixed sol to penetrate into the entire or most of the interior of the substrate. Accordingly, most or almost all of the pores inside the porous substrate can be filled with a hydroxide ion-conducting layered compound. Examples of preferred coating methods include dip coating, filter coating, etc., with dip coating being particularly preferred. The amount of mixed sol adhered can be adjusted by adjusting the number of coatings in dip coating, etc. After the substrate coated with the mixed sol by dip coating, etc., is dried, the steps (3) and (4) described above can be performed.

Claims

1. An air electrode / septum connector, wherein, have: A rigid porous layer that is both rigid and breathable, the rigidity being defined by a displacement ratio in the compression direction of less than 3% under a pressure of 0.1 MPa; An air electrode layer that covers both sides of the rigid porous layer, or both sides and one end face of the rigid porous layer, except for at least one end face; and A layered double hydroxide (LDH) separator covers both sides and end faces of the air electrode layer, except for one end face. The air electrode / separator joint is characterized in that... i) The rigid porous layer is made of conductive ceramic, thereby functioning as a positive current collector, or... ii) The rigid porous layer is made of an insulating material and is covered by a porous metal layer, wherein the porous metal layer functions as a positive current collector.

2. The air electrode / separator joint according to claim 1, characterized in that, The LDH separator is composited with a porous polymer substrate.

3. A zinc-air secondary battery, comprising the air electrode / separator assembly as described in claim 1 or 2. The zinc-air secondary battery is characterized by having: Multiple air electrode / split plate joints; Multiple negative electrode plates are alternately arranged with the air electrode / separator junction and include a negative electrode active material layer and a negative electrode current collector. The negative electrode active material layer contains at least one of the following: zinc, zinc oxide, zinc alloy and zinc compound. The outer side of the multiple negative electrode plates is not covered by a layered double hydroxide (LDH) separator. An electrolyte, which is impregnated in the negative electrode plate and the LDH separator; as well as The battery casing houses the multiple air electrode / separator joints, the multiple negative electrode plates, and the electrolyte in a vertical arrangement. The multiple negative electrode plates and the electrolyte are housed within a sealed space defined by the battery casing and the multiple air electrode / separator joints, with some remaining space at the top. The multiple air electrode / separator joints can contact the outside air through the openings in the battery casing. The battery casing is further provided with a pressure relief valve at a position facing the upper remaining space or at a position communicating with the upper remaining space, which can release any gas that may be generated inside the battery.

4. The zinc-air secondary battery according to claim 3, characterized in that, The multiple air electrode / separator joints are configured such that the end face of the rigid porous layer not covered by the LDH separator faces upward. The zinc-air secondary battery has the following features: A positive current collector is connected to the upper end of the plurality of positive current collectors via the end face of the rigid porous layer that is not covered by the LDH separator; A positive current collector terminal, which is connected to the positive current collector component and extends from the battery casing; Multiple negative current collector tabs, extending laterally from the ends of the multiple negative current collectors on their lateral sides; and A negative current collector terminal is connected to the plurality of negative current collector tabs and extends from the battery casing.

5. The zinc-air secondary battery according to claim 4, characterized in that, The positive electrode current collector has a porous structure that allows for air circulation.

6. The zinc-air secondary battery according to claim 4 or 5, characterized in that, Multiple air electrode / separator joints and multiple negative electrode plates are inserted into the battery casing without gaps in the lateral direction, and are pressed in the thickness direction of the air electrode / separator joints and the negative electrode plates by the inner wall of the battery casing.

7. The zinc-air secondary battery according to claim 4 or 5, characterized in that, A fan is also provided above the battery casing, which is used to supply air into the rigid porous layer through the end face of the rigid porous layer that is not covered by the LDH separator.

8. The zinc-air secondary battery according to claim 3, characterized in that, The multiple air electrode / separator joints are configured such that the end face of the rigid porous layer not covered by the LDH separator faces upward. The zinc-air secondary battery has the following features: A positive current collector is connected to the upper end of the plurality of positive current collectors via the end face of the rigid porous layer that is not covered by the LDH separator; A positive current collector terminal, which is connected to the positive current collector component and extends from the battery casing; Multiple negative current collector tabs, extending upwards and / or laterally from the upper end of the multiple negative current collectors; and A negative current collector terminal is connected to the plurality of negative current collector tabs and extends from the battery casing.

9. The zinc-air secondary battery according to claim 8, characterized in that, The positive electrode current collector has a porous structure that allows for air circulation.

10. The zinc-air secondary battery according to claim 8 or 9, characterized in that, Multiple air electrode / separator joints and multiple negative electrode plates are inserted into the battery casing without gaps in the lateral direction, and are pressed in the thickness direction of the air electrode / separator joints and the negative electrode plates by the inner wall of the battery casing.

11. The zinc-air secondary battery according to claim 8 or 9, characterized in that, A fan is also provided above the battery casing, which is used to supply air into the rigid porous layer through the end face of the rigid porous layer that is not covered by the LDH separator.

12. The zinc-air secondary battery according to claim 3, characterized in that, The multiple air electrode / separator joints are configured such that the end face of the rigid porous layer not covered by the LDH separator faces downward. The zinc-air secondary battery has the following features: A positive current collector is connected to the lower end of the plurality of positive current collectors via the end face of the rigid porous layer that is not covered by the LDH separator; A positive current collector terminal, which is connected to the positive current collector component and extends from the battery casing; A negative current collector component, disposed within the upper remaining space, and connected to the upper end of the plurality of negative current collectors; and A negative current collector terminal is connected to the negative current collector component and extends from the battery casing.

13. The zinc-air secondary battery according to claim 12, characterized in that, The positive electrode current collector has a porous structure that allows for air circulation.

14. The zinc-air secondary battery according to claim 12 or 13, characterized in that, Multiple air electrode / separator joints and multiple negative electrode plates are inserted into the battery casing without gaps in the lateral direction, and are pressed in the thickness direction of the air electrode / separator joints and the negative electrode plates by the inner wall of the battery casing.

15. The zinc-air secondary battery according to claim 12 or 13, characterized in that, A fan is also provided below the battery casing, which is used to supply air into the rigid porous layer through the end face of the rigid porous layer that is not covered by the LDH separator.

16. The zinc-air secondary battery according to claim 3, characterized in that, The multiple air electrode / separator joints are configured such that the end face of the rigid porous layer not covered by the LDH separator faces downward. The zinc-air secondary battery has the following features: A positive current collector is connected to the lower end of the plurality of positive current collectors via the end face of the rigid porous layer that is not covered by the LDH separator; A positive current collector terminal, which is connected to the positive current collector component and extends from the battery casing; A negative current collector component, disposed within the upper remaining space, and connected to the upper end of the plurality of negative current collectors; and A negative current collector terminal, which is connected to the negative current collector component and extends from the upper surface of the battery casing. The LDH separator is configured as an integrally connected strip opposite to the multiple air electrode / separator joints and the multiple negative electrode plates. The strip-shaped LDH separator has a tortuous structure, and the air electrode layer, the rigid porous layer and the negative electrode plate are alternately housed in multiple divisions formed by the tortuous structure, thereby separating the air electrode layer and the negative electrode plate from each other by means of the LDH separator.

17. The zinc-air secondary battery according to claim 16, characterized in that, The adjacent ends of the long strip-shaped LDH separator, which sandwich the negative electrode plate in the width direction, are heat-sealed to close the side end of the negative electrode plate. Accordingly, the portion of the long strip-shaped LDH separator that houses the negative electrode plate has a bag-like structure, in which the electrolyte is housed.

18. The zinc-air secondary battery according to claim 16 or 17, characterized in that, The ends of the long strip-shaped LDH separator along its length and / or along its width are fixed to the inner wall of the battery casing.

19. The zinc-air secondary battery according to claim 16 or 17, characterized in that, The positive electrode current collector has a porous structure that allows for air circulation.

20. The zinc-air secondary battery according to claim 16 or 17, characterized in that, Multiple air electrode / separator joints and multiple negative electrode plates are inserted into the battery casing without gaps in the lateral direction, and are pressed in the thickness direction of the air electrode / separator joints and the negative electrode plates by the inner wall of the battery casing.

21. The zinc-air secondary battery according to claim 16 or 17, characterized in that, A fan is also provided below the battery casing, which is used to supply air into the rigid porous layer through the end face of the rigid porous layer that is not covered by the LDH separator.

22. The zinc-air secondary battery according to claim 3, characterized in that, The multiple air electrode / septum assembly is configured such that the end face of the rigid porous layer not covered by the LDH septum faces downward; The zinc-air secondary battery has the following features: A positive current collector is connected to the lower end of the plurality of positive current collectors via the end face of the rigid porous layer that is not covered by the LDH separator; A positive current collector terminal, which is connected to the positive current collector component and extends from the battery casing; A negative current collector component, disposed within the upper remaining space, and connected to the upper end of the plurality of negative current collectors; and A negative current collector terminal, which is connected to the negative current collector component and extends from the side of the battery casing. The LDH separator is configured as an integrally connected strip opposite to the multiple air electrode / separator joints and the multiple negative electrode plates. The strip-shaped LDH separator has a tortuous structure, and the air electrode layer, the rigid porous layer and the negative electrode plate are alternately housed in multiple divisions formed by the tortuous structure, thereby separating the air electrode layer and the negative electrode plate from each other by means of the LDH separator.

23. The zinc-air secondary battery according to claim 22, characterized in that, The adjacent ends of the long strip-shaped LDH separator, which sandwich the negative electrode plate in the width direction, are heat-sealed to close the side end of the negative electrode plate. Accordingly, the portion of the long strip-shaped LDH separator that houses the negative electrode plate has a bag-like structure, in which the electrolyte is housed.

24. The zinc-air secondary battery according to claim 22 or 23, characterized in that, The ends of the long strip-shaped LDH separator along its length and / or along its width are fixed to the inner wall of the battery casing.

25. The zinc-air secondary battery according to claim 22 or 23, characterized in that, The positive electrode current collector has a porous structure that allows for air circulation.

26. The zinc-air secondary battery according to claim 22 or 23, characterized in that, Multiple air electrode / separator joints and multiple negative electrode plates are inserted into the battery casing without gaps in the lateral direction, and are pressed in the thickness direction of the air electrode / separator joints and the negative electrode plates by the inner wall of the battery casing.

27. The zinc-air secondary battery according to claim 22 or 23, characterized in that, A fan is also provided below the battery casing, which is used to supply air into the rigid porous layer through the end face of the rigid porous layer that is not covered by the LDH separator.

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