JP2017016901A - Zinc air cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a zinc air cell that securely separates a cathode and an anode by use of a separator even though the configuration is simplified by reducing the number of components such that a sealing structure due to the installation of the separator is minimized.SOLUTION: A zinc air cell comprises: an air electrode as a cathode; an anode containing zinc, a zinc alloy and/or a zinc compound; an electrolyte; a separator that is provided so as to separate the air electrode chamber and an anode chamber, that conducts a hydrogen ion but permeates neither water nor air; and a battery container accommodating these. The separator has the shape of a cell container. The air electrode is accommodated in this separator, and the anode and the electrolyte are accommodated in the battery container outside the separator. Alternatively, the anode and the electrolyte are accommodated in the separator and the air electrode is accommodated in the battery container outside the separator. The air electrode chamber is open to outside air. The anode chamber is a sealed space defined by the cell container type separator, cell container and/or a sealing member.SELECTED DRAWING: Figure 1A

Description

  The present invention relates to a zinc-air battery.

  One of the innovative battery candidates is a metal-air battery. In metal-air batteries, the oxygen involved in the battery reaction is supplied from the air, so the space in the battery container can be used to fill the negative electrode active material to the maximum, thereby realizing a high energy density in principle. can do.

  Many of the metal-air batteries currently proposed are lithium-air batteries. However, there are many technical problems with lithium-air batteries, such as deposition of undesirable reaction products on the air electrode, carbon dioxide contamination, and short circuit between positive and negative electrodes due to the formation of lithium dendrite (dendritic crystals). ing.

On the other hand, a zinc-air battery using zinc as a negative electrode active material has also been conventionally known. In particular, zinc-air primary batteries have already been mass-produced and are widely used as power supplies for hearing aids and the like. In a zinc-air battery, an alkaline aqueous solution such as potassium hydroxide is used as an electrolytic solution, and a separator (partition) is used to prevent a short circuit between positive and negative electrodes. At the time of discharging, as shown in the following reaction formula, O ₂ is reduced on the air electrode (positive electrode) side to generate OH ^−, while zinc is oxidized on the negative electrode to generate ZnO.
Air electrode: O ₂ + 2H ₂ O + 4e ⁻ → 4OH ⁻
Negative electrode: 2Zn + 4OH ⁻ → 2ZnO + 2H ₂ O + 4e ⁻

  Attempts have also been made to use this zinc-air battery as a secondary battery, but during charging, ZnO is reduced at the negative electrode, and metallic zinc is deposited in a dendritic form to form dendrites, and these dendrites penetrate the separator through the air. There is a problem of causing a short circuit with the electrode, which greatly hinders the practical application of zinc-air batteries as secondary batteries. In addition, on the air electrode side, carbon dioxide in the air passes through the air electrode and dissolves in the electrolytic solution, and there is a problem in that the alkaline carbonate is precipitated to deteriorate the battery performance. Compared to lithium-air batteries, zinc-air batteries do not have much of a problem with reaction, so if the problems with short circuit between positive and negative electrodes due to zinc dendrite and carbon dioxide contamination are solved, it can be realized as a high-capacity secondary battery. It is said to have a high quality. Therefore, in a zinc-air secondary battery, a technique for preventing both short-circuiting by zinc dendrite and mixing of carbon dioxide is strongly desired.

As a technique for coping with such problems or requests, Patent Document 1 (International Publication No. 2013/073292) uses a hydroxide ion conductive inorganic solid electrolyte as a separator, and an inorganic solid electrolyte is used as a separator. There has been proposed an attempt to prevent both short-circuit between positive and negative electrodes due to zinc dendrite during charging and mixing of carbon dioxide into the electrolyte by providing the air electrode in close contact with one side. Further, this document inorganic solid electrolyte body has the general ^{_{formula: M 2+ 1-x M 3+}} x (OH) 2 A n- x / n · mH 2 O ( ^{wherein, M 2+} is a divalent cation in ^{and, M 3+} is a trivalent ^{cation, a n-is} the n-valent anion, n represents an integer of 1 or more, x is has a basic composition of 0.1 to 0.4) It is also described that what consists of a layered double hydroxide is preferable.

  On the other hand, in order to obtain a high voltage and a large current, an assembled battery made by combining a plurality of single cells is widely adopted. The assembled battery has a configuration in which a stacked body in which a plurality of cells are connected in series or in parallel is housed in one battery container.

International Publication No. 2013/073292

  The present applicant has succeeded in the development of a ceramic separator (inorganic solid electrolyte separator) that has hydroxide ion conductivity but is highly densified to such an extent that it does not have water permeability and air permeability. Moreover, it has succeeded also in forming such a ceramic separator on a porous base material (for example, alumina porous base material). When a zinc-air secondary battery is configured using such a separator (or a separator with a porous substrate), the penetration of the separator by zinc dendrite generated during charging is physically blocked to prevent a short circuit between the positive and negative electrodes. In addition, the intrusion of carbon dioxide in the air can be prevented to prevent the precipitation of alkali carbonate (caused by carbon dioxide) in the electrolyte. In order to maximize this effect, it is desired to reliably partition the inside of the battery container into an air electrode side and a negative electrode side with a hydroxide ion conductive ceramic separator. In particular, when trying to securely partition the air electrode side and the negative electrode side with a flat plate hydroxide ion conductive ceramic separator, it is necessary to ensure liquid tightness at the outer peripheral edge of the separator and the joint part of the structure including the separator. An elaborate sealing structure is desired, but it is extremely advantageous if a desired liquid-tightness can be secured with a simpler configuration. In addition, in order to obtain a high voltage and a large current while securing such a configuration, it is still advantageous if a battery such as a stacked battery or a battery pack in which a plurality (preferably a large number) of unit batteries are incorporated in a space efficient manner can be configured.

  The present inventors have recently used a cell container type separator as a separator having hydroxide ion conductivity but not water permeability, thereby minimizing the sealing structure associated with the installation of the separator, and reducing the number of parts. The present inventors have obtained the knowledge that a zinc-air battery that can be reliably separated with a separator between the positive and negative electrodes (that is, between the air electrode and the negative electrode) is obtained with a simplified configuration. Moreover, according to the battery provided with such a cell container type separator, it is particularly suitable for a battery such as a laminated battery and an assembled battery in which a plurality of unit batteries are incorporated with good space efficiency, that is, in a battery such as a laminated battery and an assembled battery. It was also found that the integration density of unit cells can be greatly improved to increase the capacity.

  Therefore, an object of the present invention is to provide a zinc-air battery that can reliably separate the positive and negative electrodes with a separator while having a simplified configuration with a small number of parts and a minimum sealing structure associated with the installation of the separator. It is to provide. It is also an object of the present invention to provide a zinc-air battery that is particularly suitable for improving the integration density of unit batteries in batteries such as laminated batteries and assembled batteries.

According to one aspect of the present invention, an air electrode as a positive electrode;
A negative electrode comprising zinc, a zinc alloy and / or a zinc compound;
An electrolyte containing an aqueous alkali metal hydroxide solution in which the negative electrode is immersed;
A separator that is provided to partition the air electrode chamber that accommodates the air electrode and the negative electrode chamber that accommodates the negative electrode and the electrolyte, and has hydroxide ion conductivity but does not have water permeability and air permeability; ,
A battery container containing the air electrode, the negative electrode, the electrolytic solution, and the separator;
A zinc-air battery comprising:
The separator is a cell container type separator having a cell container shape, whereby the air electrode is accommodated in the cell container type separator, and the negative electrode and the electrolysis are included in the battery container outside the cell container type separator. Liquid is contained, or the negative electrode and the electrolytic solution are contained in the cell container type separator and the air electrode is contained in the battery container outside the cell container type separator,
There is provided a zinc-air battery in which the air electrode chamber is opened to the outside air, and the negative electrode chamber is a sealed space formed by the battery container type separator and the battery container and / or a sealing member. .

It is sectional drawing which shows typically one form of the zinc air battery by this invention. 1B is a partial cross-sectional perspective view partially showing a cross-sectional structure of the zinc-air battery shown in FIG. 1A. FIG. It is a cross-sectional perspective view which shows typically another form (assembled battery) of the zinc air battery by this invention. It is the perspective view which looked at the zinc air battery shown by FIG. 2A from diagonally upward. It is a schematic cross section which shows partially the one aspect | mode of the separator with a porous base material. It is a schematic cross section which shows partially another aspect of the separator with a porous substrate. It is a schematic diagram which shows a layered double hydroxide (LDH) plate-like particle. 2 is a SEM image of the surface of an alumina porous substrate produced in Example 1. FIG. 3 is an XRD profile obtained for the crystal phase of the sample in Example 1. 2 is an SEM image showing a surface microstructure of a film sample observed in Example 1. 2 is an SEM image of a polished cross-sectional microstructure of a composite material sample observed in Example 1. FIG. 2 is an exploded perspective view of a denseness discrimination measurement system used in Example 1. FIG. 2 is a schematic cross-sectional view of a denseness discrimination measurement system used in Example 1. FIG. FIG. 3 is an exploded perspective view of a measurement sealed container used in the denseness determination test II of Example 1. 3 is a schematic cross-sectional view of a measurement system used in the denseness determination test II of Example 1. FIG.

Zinc Air Battery FIGS. 1A and 1B schematically show one embodiment of the zinc air battery according to the present invention. A zinc-air battery 10 shown in FIGS. 1A and 1B includes an air electrode 12, a negative electrode 16, an electrolytic solution (not shown), a separator 20, and a battery container 22. The air electrode 12 functions as a positive electrode. The negative electrode 16 contains zinc, a zinc alloy, and / or a zinc compound. The electrolytic solution is a solution containing an alkali metal hydroxide aqueous solution in which the negative electrode 16 is immersed. The battery container 22 is a container that houses the air electrode 12, the negative electrode 16, the electrolytic solution, and the separator 20. The negative electrode 16 and the electrolytic solution are not necessarily separated from each other, and may be configured as a negative electrode mixture in which the negative electrode 16 and the electrolytic solution are mixed. If desired, an air electrode current collector may be provided in contact with the air electrode 12, or the battery container 22 may be formed of an air electrode current collector. Further, if desired, a negative electrode current collector 17 is provided in contact with the negative electrode 16. The separator 20 is provided in the battery container 22 so as to partition an air electrode chamber 24 that stores the air electrode 12 and a negative electrode chamber 26 that stores the negative electrode 16 and the electrolytic solution. The air electrode chamber 24 is opened to the outside air, while the negative electrode chamber 26 is a sealed space formed by the separator 20, the battery container 22, and / or a sealing member (not shown).

The separator separator 20 has hydroxide ion conductivity but does not have water permeability and air permeability. In the present specification, “not having water permeability” means “measurement object (when the water permeability is evaluated by a“ denseness determination test I ”employed in Example 1 described later) or a technique or configuration according to the“ denseness determination test I ”. For example, it means that water that contacts one side of the LDH membrane and / or porous substrate does not permeate the other side. In other words, the fact that the separator 20 does not have water permeability and air permeability means that the separator 20 has a high degree of denseness so that neither water nor gas can pass through, and a porous film having water permeability and air permeability. It means that it is not other porous material. For this reason, it has a very effective configuration for physically preventing penetration of the separator by zinc dendrite generated during charging and preventing a short circuit between the positive and negative electrodes. Needless to say, a porous substrate may be attached to the separator 20 as described later. In any case, since the separator 20 has hydroxide ion conductivity, it is possible to efficiently transfer the necessary hydroxide ions between the air electrode 12 and the electrolytic solution, and the charge in the air electrode 12 and the negative electrode 16 can be increased. A discharge reaction can be realized.

  As shown in FIGS. 1A and 1B, the separator 20 is a cell container type separator having the shape of a cell container. Thereby, as shown in FIGS. 1A and 1B, the negative electrode 16 and the electrolytic solution are accommodated in the cell container type separator 20 and the air electrode 12 is accommodated in the battery container 22 outside the cell container type separator 20, or The air electrode 12 is accommodated in the cell container type separator 20 (not shown), and the negative electrode 16 and the electrolytic solution are accommodated in the battery container 22 outside the cell container type separator 20. In the following explanation, for the convenience of explanation, the description regarding the latter mode is also written in parentheses. By using the cell container type separator in this way, it is possible to reliably separate the positive and negative electrodes with a separator while having a simplified configuration with a reduced number of parts and a minimum sealing structure associated with the installation of the separator. A zinc-air battery can be constructed. That is, when trying to partition the air electrode side and the negative electrode side with a flat plate hydroxide ion conductive ceramic separator, the liquid-tightness and air-tightness at the outer peripheral edge of the separator and the joint part of the structure including the separator are improved. Where an elaborate sealing structure is desired to ensure, such a sealing structure must be carefully constructed using frame-like members, adhesives, etc., and therefore the number of parts increases and the structure and manufacturing The method can also be complex. On the other hand, the cell container type separator 20 employed in the present invention contains the negative electrode 16 and the electrolytic solution (or the air electrode 12) therein, so that the accommodated electrode or the like can be used as the cell container type separator. Therefore, the air electrode 12 (or the negative electrode 16 and the electrolytic solution) accommodated outside the air electrode 20 can be reliably isolated. That is, since the cell container type separator 20 cannot have an outer peripheral edge or end portion in a main part that contacts the air electrode 12, the negative electrode 16, and the electrolyte due to the container shape, It is possible to minimize a sealing structure that is sealed using a frame-shaped member, an adhesive, or the like. In other words, in the zinc-air battery 10 of the present invention, the negative electrode 16 and the electrolyte (or air electrode 12) are wrapped in the cell container separator 20 itself, so that the air electrode 12 (or the negative electrode 16) is liquid-tight and air-tight. And electrolyte solution). As a result, it is possible to configure a zinc-air battery capable of reliably separating positive and negative electrodes with a separator while having a simplified configuration with a small number of parts.

  In addition, a battery provided with such a cell container type separator 20 is particularly suitable for a battery such as a laminated battery or an assembled battery in which a plurality of unit batteries are incorporated with good space efficiency. This is a one-dimensional direction in which a plurality of cell container type separators 20 in which a negative electrode 16 and an electrolytic solution (or an air electrode 12) are housed are interposed between the air electrode 12 (or the negative electrode 16 and an electrolytic solution). This is because a battery configuration that is arranged in the (x direction) or two-dimensional direction (x-y direction) is remarkably easier to adopt, and as a result, the integration density of unit cells in batteries such as laminated batteries and assembled batteries is remarkably increased. The capacity can be improved. For example, as shown in FIGS. 2A and 2B, a plurality of zinc-air batteries 10 are arranged in a desired position separated from each other (preferably regularly) in the assembled battery container 102, and are connected in parallel. A battery (for example, a parallel laminated battery or a parallel assembled battery) including a plurality of unit battery cells can be easily configured. In this case, it is preferable that the air supply path to the air electrode 12 is secured by separating the zinc-air batteries 10 from each other. Or although not shown in figure, in the matrix of the air electrode 12 (or negative electrode 16 and electrolyte solution) with which the battery container 22 was filled, several cell container type | mold separators 20 (the negative electrode 16 and electrolyte solution are contained in it) (Or the air electrode 12) is placed in a desired position (preferably regularly) and connected in parallel, so that a battery having a plurality of unit battery cells (for example, a parallel stacked battery or a parallel assembled battery) ) Can be configured relatively easily. Therefore, according to a preferred embodiment of the present invention, when the air electrode 12 is provided outside the cell container type separator 20, a plurality of zinc-air batteries are provided in the assembled battery container 102 as shown in FIGS. 2A and 2B. 10 may be spaced apart from each other. Alternatively, according to another preferred embodiment of the present invention, a plurality of cell container type separators 20 are disposed in the battery container 22 so as to be spaced apart from each other, and the negative electrode 16 and An electrolytic solution (or air electrode 12) can be accommodated.

  The cell container separator 20 may have any container shape as long as it can accommodate the negative electrode 16 and the electrolyte solution (or the air electrode 12) without omission, but is preferably a bag tube, tube, box, or bag. Shape. Since these shapes have the shape of a container, it is a premise that none of them has a bottom shape. For example, in the case of a cylindrical shape, it is needless to say that at least one end is closed. The tubular and cylindrical shapes of the bag may be circular or elliptical in cross section, square or rectangular, or a combination thereof, and are not particularly limited.

  Particularly preferably, the negative electrode 16 and the electrolytic solution are accommodated in the cell container type separator 20, and the air electrode 12 is formed along the outer wall of the cell container type separator 20 in the battery container 22 outside the cell container type separator 20. Is housed in. By doing so, even if the shape integrity of the negative electrode 16 is likely to be impaired due to charge / discharge, the shape of the negative electrode 16 is desirably maintained by the container shape of the cell container type separator 20 and continues to be involved in charge / discharge. As a result, stable battery performance can be exhibited.

  Alternatively, the air electrode 12 is accommodated in the cell container type separator 20 along the inner wall of the cell container type separator 20, and the negative electrode 16 and the electrolytic solution are accommodated in the battery container outside the cell container type separator 20. Also good.

  The separator 20 is preferably made of an inorganic solid electrolyte body. By using a hydroxide ion conductive inorganic solid electrolyte as the separator 20, the electrolytic solution is isolated from the air electrode and the hydroxide ion conductivity is secured. And since the inorganic solid electrolyte which comprises the separator 20 is typically a dense and hard inorganic solid, the penetration of the separator by the zinc dendrite produced | generated at the time of charge is blocked physically, and the short circuit between positive and negative electrodes is prevented. Is possible. As a result, the reliability of the zinc-air battery can be greatly improved. It is desirable that the inorganic solid electrolyte body is densified to such an extent that it does not have water permeability and air permeability. For example, the inorganic solid electrolyte body preferably has a relative density of 90% or more, more preferably 92% or more, and even more preferably 95% or more, calculated by the Archimedes method, but prevents penetration of zinc dendrite. It is not limited to this as long as it is as dense and hard as possible. Such a dense and hard inorganic solid electrolyte body can be produced through a hydrothermal treatment. Therefore, a simple green compact that has not been subjected to hydrothermal treatment is not preferable as the inorganic solid electrolyte body of the present invention because it is not dense and is brittle in solution. Of course, any manufacturing method can be used as long as a dense and hard inorganic solid electrolyte body can be obtained, even if it has not undergone hydrothermal treatment.

  The separator 20 or the inorganic solid electrolyte body may be a composite of a particle group including an inorganic solid electrolyte having hydroxide ion conductivity and an auxiliary component that assists densification and hardening of the particle group. Good. Alternatively, the separator 20 includes an open-pore porous body as a base material and an inorganic solid electrolyte (for example, layered double hydroxide) deposited and grown in the pores so as to fill the pores of the porous body. It may be a complex. Examples of the substance constituting the porous body include ceramics such as alumina and zirconia, and insulating substances such as a porous sheet made of a foamed resin or a fibrous substance.

The inorganic solid electrolyte has a general formula: M ²⁺ _1-x M ³⁺ _x (OH) ₂ A ⁿ⁻ _{x / n} · mH ₂ O (wherein M ²⁺ is a divalent cation and M ³⁺ is 3 the valence of the ^{cation, a n-is} the n-valent anion, n is an integer of 1 or more, x is 0.1 to 0.4, the basic composition of m is 0 or higher) It is preferable to contain a layered double hydroxide (LDH) having, more preferably, such LDH. In the above general formula, M ²⁺ may be any divalent cation, and preferred examples include Mg ²⁺ , Ca ²⁺ and Zn ²⁺ , and more preferably Mg ²⁺ . M ³⁺ may be any trivalent cation, but preferred examples include Al ³⁺ or Cr ³⁺ , and more preferred is Al ³⁺ . A ^n- may be any anion, preferred examples OH ^- and _CO ^{3 2-} and the like. Therefore, in the general ^{formula, M 2+} comprises ^{Mg 2+, M 3+} comprises ^{Al 3+, A n-is} OH ^- and / or _CO preferably contains ^{3 2-.} n is an integer of 1 or more, preferably 1 or 2. x is 0.1 to 0.4, preferably 0.2 to 0.35. More specifically, m is a real number or an integer of 0 or more, typically more than 0 or 1 or more. It is also possible to replace the part or all of the M ³⁺ in the general formula tetravalent or higher valency cation, in which case, the anion A ^n- coefficients x / n of the above general formula It may be changed as appropriate. m is an arbitrary number which means the number of moles of water, and is a real number or an integer of 0 or more, typically more than 0 or 1 or more.

  The inorganic solid electrolyte is preferably densified by hydrothermal treatment. Hydrothermal treatment is extremely effective for the densification of layered double hydroxides, especially Mg—Al type layered double hydroxides. Densification by hydrothermal treatment is performed, for example, as described in Patent Document 1 (International Publication No. 2013/118561), in which pure water and a plate-like green compact are placed in a pressure vessel, and 120 to 250 ° C., preferably The reaction can be performed at a temperature of 180 to 250 ° C. for 2 to 24 hours, preferably 3 to 10 hours. However, a more preferable production method using hydrothermal treatment will be described later.

The inorganic solid electrolyte body may be in the form of a plate, a film, or a layer. When the inorganic solid electrolyte is in the form of a film or a layer, the film or layer of the inorganic solid electrolyte is on the porous substrate or its It is preferably formed in the inside. When the plate-like form is used, sufficient hardness can be secured and penetration of zinc dendrites can be more effectively prevented. On the other hand, if the film or layer form is thinner than the plate, there is an advantage that the resistance of the separator can be significantly reduced while ensuring the minimum necessary hardness to prevent the penetration of zinc dendrite. is there. The preferred thickness of the plate-like inorganic solid electrolyte body is 0.01 to 0.5 mm, more preferably 0.02 to 0.2 mm, and still more preferably 0.05 to 0.1 mm. Moreover, the higher the hydroxide ion conductivity of the inorganic solid electrolyte body, the better, but it typically has a conductivity of 10 ⁻⁴ to 10 ⁻¹ S / m. On the other hand, in the case of a film-like or layered form, the thickness is preferably 100 μm or less, more preferably 75 μm or less, still more preferably 50 μm or less, particularly preferably 25 μm or less, and most preferably 5 μm or less. Thus, the resistance of the separator 20 can be reduced by being thin. The lower limit of the thickness is not particularly limited because it varies depending on the application, but in order to ensure a certain degree of rigidity desired as a separator film or layer, the thickness is preferably 1 μm or more, more preferably 2 μm or more. is there.

  A cell container type porous substrate having a cell container shape compatible with the cell container type separator 20 may be further provided on the negative electrode 16 side surface of the cell container type separator 20. It goes without saying that the porous substrate has water permeability, and therefore, the electrolyte solution can reach the separator 20, but the presence of the porous substrate allows hydroxide ions to be more stably formed on the separator 20. It can also be held. Moreover, since strength can be imparted by the porous substrate, the separator 20 can be thinned to reduce resistance. Also, a dense film or a dense layer of an inorganic solid electrolyte (preferably LDH) can be formed on or in the porous substrate. In the case of providing a porous substrate on one side of the separator 20, a method of preparing a porous substrate and depositing an inorganic solid electrolyte on the porous substrate can be considered (this method will be described later). In addition, although it is preferable that a porous base material is provided over the whole surface of the single side | surface of the separator 20, it is good also as a structure provided only in a part (for example, area | region in connection with charging / discharging reaction) of the single side | surface of the separator 20. FIG. For example, when the inorganic solid electrolyte is formed in a film or layer on or in the porous substrate, the porous substrate is provided over the entire surface of one side of the separator 20 due to the manufacturing method. It is typical. On the other hand, when the inorganic solid electrolyte body is formed in a self-supporting container shape (which does not require a base material), the porous base material is provided only on a part of one side of the separator 20 (for example, a region involved in the charge / discharge reaction). It may be retrofitted or a porous substrate may be retrofitted over the entire surface of one side.

  In addition, a second separator (resin separator) made of a water-absorbing resin such as a nonwoven fabric or a liquid-retaining resin is disposed between the negative electrode 16 and the separator 20, so that the electrolytic solution can be used even when the electrolytic solution is reduced. It is good also as a structure which can hold | maintain electrolyte solution in this reaction part. Preferable examples of the water absorbent resin or the liquid retaining resin include polyolefin resins.

The air electrode 12 is not particularly limited and may be a known air electrode used in metal-air batteries such as zinc-air batteries. The air electrode 12 typically includes an air electrode catalyst, an electronically conductive material, and optionally a hydroxide ion conductive material. However, when an air electrode catalyst that also functions as an electron conductive material is used, the air electrode 12 includes such an electron conductive material / air electrode catalyst and, optionally, a hydroxide ion conductive material. There may be.

  The air electrode catalyst is not particularly limited as long as it functions as a positive electrode in a metal-air battery, and various air electrode catalysts that can use oxygen as a positive electrode active material can be used. Preferred examples of the air electrode catalyst include carbon-based materials having a redox catalyst function such as graphite, metals having a redox catalyst function such as platinum and nickel, perovskite oxides, manganese dioxide, nickel oxide, cobalt oxide, spinel. Examples thereof include inorganic oxides having a redox catalyst function such as oxides. The shape of the air electrode catalyst is not particularly limited, but is preferably a particle shape. Although content of the air electrode catalyst in the air electrode 12 is not specifically limited, 5-70 volume% is preferable with respect to the total amount of the air electrode 12, More preferably, it is 5-60 volume%, More preferably, it is 5-50 volume. %.

  The electron conductive material is not particularly limited as long as it has conductivity and enables electron conduction between the air electrode catalyst and the separator 20 (or an intermediate layer to be described later if applicable). Preferred examples of the electron conductive material include carbon blacks such as ketjen black, acetylene black, channel black, furnace black, lamp black, and thermal black, natural graphite such as flake graphite, artificial graphite, and expanded graphite. Examples thereof include conductive fibers such as graphites, carbon fibers, and metal fibers, metal powders such as copper, silver, nickel, and aluminum, organic electron conductive materials such as polyphenylene derivatives, and any mixture thereof. The shape of the electron conductive material may be a particle shape or any other shape, but is used in a form that provides a continuous phase (that is, an electron conductive phase) in the thickness direction in the air electrode 12. Is preferred. For example, the electron conductive material may be a porous material. The electron conductive material may be in the form of a mixture or complex with an air electrode catalyst (for example, platinum-supported carbon). As described above, an air electrode catalyst (for example, a transition metal) that also functions as an electron conductive material. Perovskite-type compounds). Although content of the electron conductive material in the air electrode 12 is not specifically limited, 10-80 volume% is preferable with respect to the total amount of the air electrode 12, More preferably, it is 15-80 volume%, More preferably, it is 20-80. % By volume.

The air electrode 12 may further contain a hydroxide ion conductive material as an optional component. In particular, when the separator 20 is made of a hydroxide ion conductive inorganic solid electrolyte, which is a dense ceramic, on the separator 20 (with an intermediate layer having hydroxide ion conductivity if desired), conventionally. By forming the air electrode 12 containing not only the air electrode catalyst and the electron conductive material to be used but also the hydroxide ion conductive material, the desired characteristics by the separator 20 made of dense ceramics are ensured. However, it is possible to reduce the reaction resistance of the air electrode in the metal-air battery. That is, not only the air electrode catalyst and the electron conductive material, but also the hydroxide ion conductive material is contained in the air electrode 12 so that the electron conductive phase (electron conductive material), the gas phase (air), The three-phase interface consisting of is present not only in the interface between the separator 20 (or the intermediate layer, if applicable) and the air electrode 12, but also in the air electrode 12, and exchanges hydroxide ions that contribute to the battery reaction. As a result, the reaction resistance of the air electrode is considered to be reduced in the metal-air battery. The hydroxide ion conductive material is not particularly limited as long as it is a material that can transmit hydroxide ions, and various materials and forms of materials can be used regardless of whether the material is an inorganic material or an organic material. It may be a layered double hydroxide having a basic composition. The hydroxide ion conductive material is not limited to the particle form, but may be in the form of a coating film that partially or substantially entirely covers the air electrode catalyst and the electron conductive material. However, even in the form of the coating film, the ion conductive material is not dense and has open pores, and the interface from the outer surface of the air electrode 12 to the separator 20 (or an intermediate layer if applicable). It is desirable that O ₂ or H ₂ O can be diffused in the pores. The content of the hydroxide ion conductive material in the air electrode 12 is not particularly limited, but is preferably 0 to 95% by volume, more preferably 5 to 85% by volume, and still more preferably based on the total amount of the air electrode 12. 10 to 80% by volume.

  The formation of the air electrode 12 may be performed by any method and is not particularly limited. For example, an air electrode catalyst, an electron conductive material, and optionally a hydroxide ion conductive material are wet-mixed using a solvent such as ethanol, dried and crushed, and then mixed with a binder to obtain a fibril. The fibrillar mixture is pressure-bonded to a current collector to form an air electrode 12, and the air electrode 12 side of the air electrode 12 / current collector laminated sheet is pressure-bonded to a separator 20 (or an intermediate layer if applicable). May be. Alternatively, an air electrode catalyst, an electron conductive material, and, if desired, a hydroxide ion conductive material are wet-mixed with a solvent such as ethanol to form a slurry, and this slurry is applied to an intermediate layer and dried to form the air electrode 12. It may be formed. Therefore, the air electrode 12 may contain a binder. The binder may be a thermoplastic resin or a thermosetting resin and is not particularly limited.

  The air electrode 12 is preferably in a layered form having a thickness of 5 to 200 μm, more preferably 5 to 100 μm, still more preferably 5 to 50 μm, and particularly preferably 5 to 30 μm. For example, when a hydroxide ion conductive material is included, if the thickness is within the above range, a relatively large area of the three-phase interface can be secured while suppressing an increase in gas diffusion resistance, and the reaction of the air electrode Reduction of resistance can be realized more preferably.

  An intermediate layer may be provided between the separator 20 and the air electrode 12. The intermediate layer is not particularly limited as long as it improves the adhesion between the separator 20 and the air electrode 12 and has hydroxide ion conductivity, regardless of whether it is an organic material or an inorganic material. Layer. The intermediate layer preferably includes a polymer material and / or a ceramic material. In this case, it is sufficient that at least one of the polymer material and the ceramic material included in the intermediate layer has hydroxide ion conductivity. . A plurality of intermediate layers may be provided, and the plurality of intermediate layers may be the same type and / or different layers. That is, the intermediate layer may have a single layer structure or a structure having two or more layers. The intermediate layer preferably has a thickness of 1 to 200 μm, more preferably 1 to 100 μm, still more preferably 1 to 50 μm, and particularly preferably 1 to 30 μm. With such a thickness, the adhesion between the separator 20 and the air electrode 12 can be easily improved, and the battery resistance (particularly, the interface resistance between the air electrode and the separator) can be more effectively reduced in the zinc-air secondary battery. Can do.

  An air electrode current collector is preferably provided in contact with the air electrode 12, and the air electrode current collector preferably has air permeability so that air is supplied to the air electrode 12. In this regard, as shown in FIGS. 1A and 1B, the battery container 22 is formed of an air cathode current collector having air permeability, whereby the air electrode current collector (ie, the battery container 22) is in contact with the air electrode. It is preferable that the configuration is as follows. As shown in FIGS. 1A and 1B, the air electrode current collector protrudes from the upper end of the battery case 22, and may constitute the air electrode terminal 22a itself. It is good also as a structure connected outside. Preferable examples of the air electrode current collector include metal plates or metal meshes such as stainless steel, copper and nickel, carbon paper, carbon cloth, and electron conductive oxide. Stainless steel is used in terms of corrosion resistance and air permeability. A wire mesh is particularly preferred.

The negative electrode negative electrode 16 includes zinc, a zinc alloy and / or a zinc compound that functions as a negative electrode active material. The negative electrode 16 may have any shape or form such as a particle shape, a plate shape, or a gel shape, but a particle shape or a gel shape is preferable in terms of reaction rate. As the particulate negative electrode, those having a particle diameter of 30 to 350 μm can be preferably used. As the gelled negative electrode, a gelled negative electrode alloy having a particle size of 100 to 300 μm, an alkaline electrolyte and a thickener (gelling agent) mixed and stirred to form a gel can be preferably used. . The zinc alloy can be a hatched or non-hatched alloy such as magnesium, aluminum, lithium, bismuth, indium, lead, etc., and its content is not particularly limited as long as desired performance can be secured as a negative electrode active material. . Preferred zinc alloys are anhydrous silver and lead-free zinc-free zinc alloys, more preferably those containing aluminum, bismuth, indium or combinations thereof. More preferably, it is a zinc-free zinc alloy containing 50 to 1000 ppm of bismuth, 100 to 1000 ppm of indium, and 10 to 100 ppm of aluminum and / or calcium, particularly preferably 100 to 500 ppm of bismuth, 300 to 700 ppm of indium, Contains 20 to 50 ppm of aluminum and / or calcium. Examples of preferred zinc compounds include zinc oxide.

  A negative electrode current collector 17 is preferably provided in contact with the negative electrode 16. As shown in FIGS. 1A and 1B, the negative electrode current collector 17 passes through the top cover or sealing member (not shown) of the battery container 22 and extends to the outside thereof to constitute the negative electrode terminal 17a itself. Or it is good also as a structure connected to the negative electrode terminal provided separately in the battery container 22 or outside. Preferable examples of the negative electrode current collector 17 include a metal plate or metal mesh such as stainless steel, copper (for example, copper punching metal), nickel, carbon paper, and an oxide conductor. In this case, for example, a negative electrode composed of negative electrode 16 / negative electrode current collector 17 by applying a mixture containing zinc oxide powder and / or zinc powder and optionally a binder (for example, polytetrafluoroethylene particles) on copper punching metal. A plate can be preferably produced. At that time, it is also preferable to press the dried negative electrode plate (that is, negative electrode 16 / negative electrode current collector 17) to prevent the electrode active material from falling off and to improve the electrode density.

If desired, the zinc-air battery 10 (especially the negative electrode chamber 26) may include a third electrode (not shown) provided so as to be in contact with the electrolyte but not in contact with the negative electrode 16. The third electrode is connected to the air electrode 12 via an external circuit. With this configuration, hydrogen gas that can be generated from the negative electrode 16 by side reaction is brought into contact with the third electrode, and the following reaction is performed:
Third electrode: H ₂ + 2OH ⁻ → 2H ₂ O + 2e ⁻
Air electrode discharge: O ₂ + 2H ₂ O + 4e ⁻ → 4OH ⁻
Can be returned to the water. In other words, the hydrogen gas generated at the negative electrode 16 is absorbed by the third electrode and self-discharged. As a result, an increase in internal pressure in the negative electrode-side sealed space due to the generation of hydrogen gas and the accompanying problems can be suppressed or avoided, and water (which will be reduced according to the above reaction formula along with the discharge reaction) is generated and the negative electrode-side sealed Water shortage in the space can be suppressed or avoided. That is, the hydrogen gas generated from the negative electrode can be recycled by returning it to water in the negative electrode-side sealed space. As a result, a highly reliable zinc-air secondary battery that can cope with the problem of hydrogen gas generation while having a configuration that is extremely effective in preventing both short-circuiting due to zinc dendrite and carbon dioxide contamination. Can be provided.

The third electrode is not particularly limited as long as it is an electrode capable of converting hydrogen gas (H ₂ ) into water (H ₂ O) by the reaction as described above by being connected to the air electrode 12 through an external circuit. It is desirable that the oxygen overvoltage is larger than that of the air electrode 12. It is also desirable that the third electrode does not participate in normal charge / discharge reactions. The third electrode preferably includes platinum and / or a carbon material, and more preferably includes a carbon material. Preferable examples of the carbon material include natural graphite, artificial graphite, hard carbon, soft carbon, carbon fiber, carbon nanotube, graphene, activated carbon, and any combination thereof. Although the shape of a 3rd electrode is not specifically limited, It is preferable to set it as the shape (for example, mesh shape or particle shape) that a specific surface area becomes large. More preferably, the third electrode (preferably the third electrode having a large specific surface area) is applied and / or disposed on the current collector. The current collector for the third electrode may have any shape, but preferable examples include a wire (for example, a wire), a punching metal, a mesh, a foam metal, and any combination thereof. The material for the current collector for the third electrode may be the same material as the material for the third electrode, or may be a metal (for example, nickel), an alloy, or other conductive material.

  The third electrode is in contact with the electrolytic solution, but it is desirable that the third electrode be disposed at a place not directly related to the normal charge / discharge reaction. In this case, a water retention member made of a water absorbent resin such as a nonwoven fabric or a liquid retention resin is disposed in the negative electrode side sealed space so as to be in contact with the third electrode. It is preferable that the three electrodes be held so as to be always contactable. A commercially available battery separator can also be used as the water retaining member. Preferable examples of the water absorbent resin or the liquid retaining resin include polyolefin resins. The third electrode does not necessarily need to be impregnated with a large amount of electrolytic solution, and can exhibit a desired function even when wet with a small amount or a small amount of electrolytic solution. Should have.

The electrolytic solution contains an alkali metal hydroxide aqueous solution. Examples of the alkali metal hydroxide include potassium hydroxide and sodium hydroxide, and potassium hydroxide is more preferable. In order to suppress self-dissolution of the zinc alloy, a zinc compound such as zinc oxide or zinc hydroxide may be added to the electrolytic solution. As described above, the electrolytic solution may be mixed with the negative electrode 16 and exist in the form of the negative electrode mixture. Further, the electrolytic solution may be gelled in order to prevent leakage of the electrolytic solution. As the gelling agent, it is desirable to use a polymer that swells by absorbing the solvent of the electrolytic solution, and polymers such as polyethylene oxide, polyvinyl alcohol, and polyacrylamide, and starch are used.

Battery Container The battery container 22 is a container that houses the air electrode 12, the negative electrode 16, and the electrolytic solution. What is necessary is just to comprise the battery container 22 with the optimal material and structure according to the component (namely, the air electrode 12, or the negative electrode 16, and electrolyte solution) which touches it.

  That is, as shown in FIGS. 1A and 1B, when the air electrode 12 is accommodated in the battery container 22 outside the cell container type separator 20, the battery container 22 preferably includes an air electrode current collector, The battery container 22 is preferably composed of an air electrode current collector. As described above, the air electrode current collector preferably has air permeability, and the material thereof is as described above. Of course, as long as supply of air to the air electrode 12 is ensured, the battery container 22 may not include the air electrode current collector, and in that case, the air electrode current collector (preferably having air permeability) is used. What is necessary is just to provide separately in the desired position which can contact the air electrode 12 in the battery container 22. FIG. 1A and 1B, the battery container 22 can have a bag-like tubular or cylindrical shape. In this case, the air electrode chamber 24 (air) is formed from the inner wall of the battery container 22 toward the center of the zinc-air battery 10. Electrode 12, including air electrode current collector), separator 20, and negative electrode chamber 26 (including negative electrode 16, negative electrode current collector 17, and electrolyte). It goes without saying that the battery container 22 may have a shape other than the tubular or cylindrical shape as shown in FIGS. 1A and 1B. For example, the battery container 22 may be configured in a box shape. In this case, a separator is provided in the air electrode chamber 24 (including the air electrode 12 and the air electrode current collector) formed in contact with the inner wall of the battery container 22. One or a plurality of negative electrode chambers 26 (including the negative electrode 16, the negative electrode current collector 17, and the electrolyte solution) separated by 20 may be provided. According to such a configuration, it is possible to provide a thin and compact zinc-air battery in which the constituent members are housed efficiently.

  On the other hand, although not shown, when the negative electrode 16 and the electrolytic solution are accommodated in the battery container 22 outside the cell container separator 20, the material of the battery container 22 is based on an alkali metal hydroxide such as potassium hydroxide. The resin is not particularly limited as long as it has resistance, and is preferably made of a resin such as polyolefin resin, ABS resin, or modified polyphenylene ether, and more preferably ABS resin or modified polyphenylene ether. The battery container 22 can have a bag-like or cylindrical shape. In this case, the negative electrode chamber 26 (the negative electrode 16, the negative electrode current collector 17, and the electrolyte solution) extends from the inner wall of the battery container 22 toward the center of the zinc-air battery 10. ), A separator 20, and an air electrode chamber 24 (including the air electrode 12 and the air electrode current collector). Needless to say, the battery container 22 may have a shape other than the tubular or cylindrical shape. For example, the battery container 22 may be configured in a box shape, and in this case, in the negative electrode chamber 26 (including the negative electrode 16, the negative electrode current collector 17, and the electrolytic solution) formed in contact with the inner wall of the battery container 22. One or a plurality of air electrode chambers 24 (including the air electrode 12 and the air electrode current collector) separated by the separator 20 may be provided. According to such a configuration, it is possible to provide a thin and compact zinc-air battery in which the constituent members are housed efficiently.

  The air electrode chamber 24 is opened to the outside air, while the negative electrode chamber 26 is a sealed space formed by the separator 20, the battery container 22 and / or a sealing member (not shown). That is, the negative electrode chamber 26 is desired to have a structure having liquid tightness and air tightness. For example, in the case of an open battery container 22 without an upper lid, a sealing member for sealing the negative electrode chamber 26 in a liquid-tight and air-tight manner may be provided in the opening at the upper end of the cell container-type separator 20. The chamber 26 can form a sealed space by the cell container type separator 20 and the sealing member. Since the cell container type separator 20 has only one opening at the upper end due to its container shape, it is much easier to seal than the plate separator. Alternatively, the battery container 22 may have an upper lid for the negative electrode chamber 26 to form a sealed space with the cell container type separator 20. In this case, the upper lid seals the negative electrode chamber 26 in the battery container 22. At the same time, it is desirable to have an opening for opening the cathode chamber 24 to the outside air. In any case, the air electrode chamber 24 is opened to the outside air, while the negative electrode chamber 26 is a sealed space formed by the separator 20, the battery container 22 and / or a sealing member (not shown). In the negative electrode chamber 26 thus formed as a sealed space, liquid tightness and air tightness can be ensured. Needless to say, it is preferable that the joining portion between the separator 20 and the battery container 22 (in particular, the upper lid) and / or the sealing member is sealed with an adhesive or the like.

  It is preferable that the zinc-air battery 10 has a surplus space (not shown) having a volume that allows a decrease in the amount of water accompanying the negative electrode reaction during charging / discharging in the negative electrode chamber 26. As a result, it is possible to effectively prevent problems associated with the increase or decrease in the amount of water in the negative electrode chamber 26 (for example, liquid leakage, deformation of the container due to changes in the container internal pressure, etc.) and further improve the reliability of the zinc-air battery. it can. That is, as can be seen from the reaction equation described above, water decreases in the negative electrode chamber 26 during charging, while water increases in the negative electrode chamber 26 during discharging. In this respect, since most conventional separators have water permeability, water can freely pass through the separators. However, since the separator 20 used in the present invention has a highly dense structure that does not have water permeability, water cannot freely pass through the separator 20, and the amount of electrolyte in the negative electrode chamber 26 increases with charge / discharge. It may increase unilaterally and cause problems such as liquid leakage. In view of this, the negative electrode chamber 26 has an excess space with a volume that allows a decrease in the amount of water accompanying the negative electrode reaction during charging and discharging. The amount of increase / decrease in moisture in the negative electrode chamber 26 can be calculated based on the reaction formula described above.

  When the zinc-air battery 10 is constructed in a discharged state, the surplus space has a volume exceeding the amount of water expected to decrease with the negative electrode reaction during charging, and the surplus space may decrease. It is preferable that an expected amount of electrolyte is filled in advance. On the other hand, when the zinc-air battery 10 is constructed in a fully charged state, the surplus space has a volume exceeding the amount of moisture expected to increase with the negative electrode reaction during discharge, and the surplus space has an electrolyte solution. Is preferably not pre-filled.

  The zinc-air battery of the present invention is preferably configured in a vertical structure in which the cell container type separator 20 is provided vertically. When the separator is provided vertically, the air electrode chamber / separator / negative electrode chamber / separator / air electrode chamber are arranged in the horizontal direction (horizontal direction). When the separator 20 is provided vertically as in FIGS. 1A and 1B, the negative electrode chamber 26 typically has an excess space above it. However, when the gel electrolyte is used, the electrolyte can be held in the charge / discharge reaction portion of the negative electrode chamber 26 despite the decrease in the electrolyte, and therefore, the portion other than the upper portion of the negative electrode chamber 26 (for example, It is also possible to provide an extra space in the side portion and the lower portion), and the degree of freedom in design increases.

LDH separator with porous substrate As described above, the separator with a porous substrate preferably used for the secondary battery of the present invention is a separator composed of an inorganic solid electrolyte having hydroxide ion conductivity, and at least one of the separators. And a porous substrate provided on the surface. The separator and the porous base material preferably both have the shape of the cell container as described above, but only the layer structure of the separator and the porous base material will be described below (therefore, the cell container). The description of the shape is omitted here). The inorganic solid electrolyte body is in the form of a film or layer that is so dense that it does not have water permeability. A particularly preferred separator with a porous substrate comprises a porous substrate and a separator layer formed on and / or in the porous substrate, and the separator layer is layered as described above. It contains double hydroxide (LDH). The separator layer preferably does not have water permeability and air permeability. That is, the porous material can have water permeability and air permeability due to the presence of pores, but the separator layer is preferably densified with LDH to such an extent that it does not have water permeability and air permeability. The separator layer is preferably formed on a porous substrate. For example, as shown in FIG. 3, the separator layer 120 is preferably formed as an LDH dense film on the porous substrate 128. In this case, it goes without saying that LDH may also be formed on the surface of the porous substrate 128 and in the pores in the vicinity thereof as shown in FIG. 3 due to the nature of the porous substrate 128. Alternatively, as shown in FIG. 4, LDH is densely formed in the porous substrate 128 (for example, in the surface of the porous substrate 128 and in the pores in the vicinity thereof), whereby at least one of the porous substrates 128 is formed. The part may constitute separator layer 120 ′. In this regard, the embodiment shown in FIG. 4 has a configuration in which the membrane equivalent portion in the separator layer 120 of the embodiment shown in FIG. 3 is removed, but is not limited to this, and is parallel to the surface of the porous substrate 128. A separator layer only needs to be present. In any case, since the separator layer is densified with LDH to such an extent that it does not have water permeability and air permeability, it has hydroxide ion conductivity but does not have water permeability and air permeability (ie basically It can have a unique function of passing only hydroxide ions).

  The porous substrate is preferably capable of forming an LDH-containing separator layer on and / or in the porous substrate, and the material and the porous structure are not particularly limited. Typically, an LDH-containing separator layer is formed on and / or in a porous substrate, but an LDH-containing separator layer is formed on a non-porous substrate and then non-porous by various known techniques. The porous substrate may be made porous. In any case, it is preferable that the porous base material has a porous structure having water permeability in that the electrolyte solution can reach the separator layer when incorporated into the battery as a battery separator.

  The porous substrate is preferably composed of at least one selected from the group consisting of ceramic materials, metal materials, and polymer materials. More preferably, the porous substrate is made of a ceramic material. In this case, preferable examples of the ceramic material include alumina, zirconia, titania, magnesia, spinel, calcia, cordierite, zeolite, mullite, ferrite, zinc oxide, silicon carbide, aluminum nitride, silicon nitride, and any combination thereof. More preferred are alumina, zirconia, titania, and any combination thereof, particularly preferred are alumina and zirconia, and most preferred is alumina. When these porous ceramics are used, it is easy to form an LDH-containing separator layer having excellent denseness. Preferable examples of the metal material include aluminum and zinc. Preferred examples of the polymer material include polystyrene, polyethersulfone, polypropylene, epoxy resin, polyphenylene sulfide, and any combination thereof. It is more preferable to appropriately select a material excellent in alkali resistance as the resistance to the battery electrolyte from the various preferable materials described above.

  The porous substrate preferably has an average pore diameter of 0.001 to 1.5 μm, more preferably 0.001 to 1.25 μm, still more preferably 0.001 to 1.0 μm, and particularly preferably 0.001. It is -0.75 micrometer, Most preferably, it is 0.001-0.5 micrometer. By setting it within these ranges, it is possible to form an LDH-containing separator layer that is so dense that it does not have water permeability while ensuring desired water permeability in the porous substrate. In the present invention, the average pore diameter can be measured by measuring the longest distance of the pores based on an electron microscope (SEM) image of the surface of the porous substrate. The magnification of the electron microscope (SEM) image used for this measurement is 20000 times, and all obtained pore diameters are arranged in order of size, and the top 15 points and the bottom 15 points from the average value, with 30 points per field of view in total. The average pore diameter can be obtained by calculating an average value for two visual fields. For the length measurement, a length measurement function of SEM software, image analysis software (for example, Photoshop, manufactured by Adobe) or the like can be used.

  The surface of the porous substrate preferably has a porosity of 10 to 60%, more preferably 15 to 55%, and still more preferably 20 to 50%. By setting it within these ranges, it is possible to form an LDH-containing separator layer that is so dense that it does not have water permeability while ensuring desired water permeability in the porous substrate. Here, the porosity of the surface of the porous substrate is adopted because it is easy to measure the porosity using the image processing described below, and the porosity of the surface of the porous substrate. This is because it can be said that it generally represents the porosity inside the porous substrate. That is, if the surface of the porous substrate is dense, the inside of the porous substrate can be said to be dense as well. In the present invention, the porosity of the surface of the porous substrate can be measured as follows by a technique using image processing. That is, 1) An electron microscope (SEM) image of the surface of the porous substrate (acquisition of 10,000 times or more) is obtained, and 2) a grayscale SEM image is read using image analysis software such as Photoshop (manufactured by Adobe). 3) Create a black-and-white binary image by the procedure of [Image] → [Tonal Correction] → [Turn Tone], and 4) The value obtained by dividing the number of pixels occupied by the black part by the total number of pixels in the image Rate (%). The porosity measurement by this image processing is preferably performed for a 6 μm × 6 μm region on the surface of the porous substrate. In order to obtain a more objective index, three arbitrarily selected regions are used. It is more preferable to employ the average value of the obtained porosity.

  The separator layer is formed on the porous substrate and / or in the porous substrate, preferably on the porous substrate. For example, when the separator layer 120 is formed on the porous substrate 128 as shown in FIG. 3, the separator layer 120 is in the form of an LDH dense film, typically from the LDH. Become. In addition, as shown in FIG. 4, when the separator layer 120 ′ is formed in the porous substrate 128, the surface of the porous substrate 128 (typically the surface of the porous substrate 128 and the vicinity thereof). Since the LDH is densely formed in the pores), the separator layer 120 ′ is typically composed of at least a part of the porous substrate 128 and LDH. The separator layer 120 ′ shown in FIG. 4 can be obtained by removing a portion corresponding to the film in the separator layer 120 shown in FIG. 3 by a known method such as polishing or cutting.

  The separator layer preferably does not have water permeability and air permeability. For example, the separator layer does not allow permeation of water even if one side of the separator layer is brought into contact with water at 25 ° C. for 1 week, and does not allow permeation of helium gas even if helium gas is pressurized on the one side with an internal / external pressure difference of 0.5 atm. . That is, the separator layer is preferably densified with LDH to such an extent that it does not have water permeability and air permeability. However, when a defect having water permeability locally and / or accidentally exists in the functional film, the defect is filled with an appropriate repair agent (for example, epoxy resin) to repair the water impermeability and Gas impermeability may be ensured and such repair agents need not necessarily have hydroxide ion conductivity. In any case, the surface of the separator layer (typically the LDH dense film) preferably has a porosity of 20% or less, more preferably 15% or less, still more preferably 10% or less, and particularly preferably 7%. It is as follows. It means that the lower the porosity of the surface of the separator layer, the higher the density of the separator layer (typically the LDH dense film), which is preferable. Here, the porosity of the surface of the separator layer is adopted because it is easy to measure the porosity using the image processing described below, and the porosity of the surface of the separator layer is determined inside the separator layer. It is because it can be said that the porosity of is generally expressed. That is, if the surface of the separator layer is dense, it can be said that the inside of the separator layer is also dense. In the present invention, the porosity of the surface of the separator layer can be measured as follows by a technique using image processing. That is, 1) An electron microscope (SEM) image (10,000 times or more magnification) of the surface of the separator layer is acquired, and 2) a gray-scale SEM image is read using image analysis software such as Photoshop (manufactured by Adobe). ) Create a black-and-white binary image by the procedure of [Image] → [Tone Correction] → [2 Gradation], and 4) Porosity (the value obtained by dividing the number of pixels occupied by the black part by the total number of pixels in the image) %). The porosity measurement by this image processing is preferably performed for a 6 μm × 6 μm region on the surface of the separator layer. In order to obtain a more objective index, it is obtained for three arbitrarily selected regions. It is more preferable to adopt the average value of the porosity.

  The layered double hydroxide is composed of an aggregate of a plurality of plate-like particles (that is, LDH plate-like particles), and the plurality of plate-like particles are substantially the same as the surface of the porous substrate (substrate surface). It is preferably oriented in a direction that intersects perpendicularly or diagonally. As shown in FIG. 3, this embodiment is a particularly preferable and feasible embodiment when the separator layer 120 is formed as an LDH dense film on the porous substrate 128, but as shown in FIG. LDH is densely formed in the porous substrate 128 (typically in the surface of the porous substrate 128 and in the vicinity thereof), whereby at least a part of the porous substrate 128 forms the separator layer 120 ′. This can be realized even in the case of configuration.

  That is, the LDH crystal is known to have the form of a plate-like particle having a layered structure as shown in FIG. 5, but the substantially vertical or oblique orientation is determined by the LDH-containing separator layer (for example, an LDH dense film). This is a very advantageous property. This is because, in an oriented LDH-containing separator layer (for example, an oriented LDH dense film), the hydroxide ion conductivity in the direction in which the LDH plate-like particles are oriented (that is, the direction parallel to the LDH layer) is perpendicular to this. This is because there is a conductivity anisotropy that is much higher than the conductivity in the direction. In fact, the present applicant has obtained knowledge that the conductivity (S / cm) in the alignment direction is one order of magnitude higher than the conductivity (S / cm) in the direction perpendicular to the alignment direction in the LDH oriented bulk body. ing. That is, the substantially vertical or oblique orientation in the LDH-containing separator layer of the present embodiment indicates the conductivity anisotropy that the LDH oriented body can have in the layer thickness direction (that is, the direction perpendicular to the surface of the separator layer or porous substrate). As a result, the conductivity in the layer thickness direction can be maximized or significantly increased. In addition, since the LDH-containing separator layer has a layer form, lower resistance can be realized than a bulk form LDH. An LDH-containing separator layer having such an orientation is easy to conduct hydroxide ions in the layer thickness direction. In addition, since it is densified, it is extremely suitable for a separator that requires high conductivity and denseness in the layer thickness direction.

  Particularly preferably, the LDH plate-like particles are highly oriented in a substantially vertical direction in the LDH-containing separator layer (typically an LDH dense film). This high degree of orientation is confirmed by the fact that when the surface of the separator layer is measured by an X-ray diffraction method, the peak of the (003) plane is not substantially detected or smaller than the peak of the (012) plane. (However, when a porous substrate in which a diffraction peak is observed at the same position as the peak due to the (012) plane is used, the peak of the (012) plane due to the LDH plate-like particle is used. This is not the case). This characteristic peak characteristic indicates that the LDH plate-like particles constituting the separator layer are oriented in a substantially vertical direction (that is, a vertical direction or an oblique direction similar thereto, preferably a vertical direction) with respect to the separator layer. That is, the (003) plane peak is known as the strongest peak observed when X-ray diffraction is performed on non-oriented LDH powder. In the oriented LDH-containing separator layer, the LDH plate-like particles are separated from the separator. By being oriented in a direction substantially perpendicular to the layer, the peak of the (003) plane is not substantially detected or detected smaller than the peak of the (012) plane. This is because the c-axis direction (00l) plane (l is 3 and 6) to which the (003) plane belongs is a plane parallel to the layered structure of the LDH plate-like particles. On the other hand, when oriented in a substantially vertical direction, the LDH layered structure also faces in a substantially vertical direction. As a result, when the separator layer surface is measured by an X-ray diffraction method, the (00l) plane (l is 3 and 6). This is because the peak of) does not appear or becomes difficult to appear. In particular, the peak of the (003) plane tends to be stronger than the peak of the (006) plane when it exists, so it is easier to evaluate the presence / absence of orientation in the substantially vertical direction than the peak of the (006) plane. I can say that. Therefore, in the oriented LDH-containing separator layer, the (003) plane peak is substantially not detected or smaller than the (012) plane peak, suggesting a high degree of vertical orientation. It can be said that it is preferable.

  The separator layer preferably has a thickness of 100 μm or less, more preferably 75 μm or less, further preferably 50 μm or less, particularly preferably 25 μm or less, and most preferably 5 μm or less. Thus, the resistance of the separator can be reduced by being thin. The separator layer is preferably formed as an LDH dense film on the porous substrate. In this case, the thickness of the separator layer corresponds to the thickness of the LDH dense film. When the separator layer is formed in the porous substrate, the thickness of the separator layer corresponds to the thickness of the composite layer composed of at least part of the porous substrate and LDH, and the separator layer is porous. When formed over and in the substrate, this corresponds to the total thickness of the LDH dense film and the composite layer. In any case, when the thickness is as described above, a desired low resistance suitable for practical use in battery applications and the like can be realized. The lower limit of the thickness of the LDH alignment film is not particularly limited because it varies depending on the application, but in order to ensure a certain degree of hardness desired as a functional film such as a separator, the thickness is preferably 1 μm or more. Preferably it is 2 micrometers or more.

The above-mentioned LDH separator with a porous substrate is (1) a porous substrate is prepared, and (2) a total of 0.20 to 0.40 mol / L of magnesium ions (Mg ²⁺ ) and aluminum ions (Al ³⁺ ). The porous substrate is immersed in a raw material aqueous solution containing urea at a concentration and (3) hydrothermally treating the porous substrate in the raw material aqueous solution, and the separator layer containing the layered double hydroxide is porous. It can be produced by forming on a substrate and / or in a porous substrate.

(1) Preparation of porous substrate The porous substrate is as described above, and is preferably composed of at least one selected from the group consisting of ceramic materials, metal materials, and polymer materials. More preferably, the porous substrate is made of a ceramic material. In this case, preferable examples of the ceramic material include alumina, zirconia, titania, magnesia, spinel, calcia, cordierite, zeolite, mullite, ferrite, zinc oxide, silicon carbide, aluminum nitride, silicon nitride, and any combination thereof. More preferred are alumina, zirconia, titania, and any combination thereof, particularly preferred are alumina and zirconia, and most preferred is alumina. When these porous ceramics are used, the density of the LDH-containing separator layer tends to be improved. When using a porous substrate made of a ceramic material, it is preferable to subject the porous substrate to ultrasonic cleaning, cleaning with ion exchange water, and the like.

(2) Immersion in raw material aqueous solution Next, the porous substrate is immersed in the raw material aqueous solution in a desired direction (for example, horizontally or vertically). When the porous substrate is held horizontally, the porous substrate may be suspended, floated, or disposed so as to be in contact with the bottom of the container. For example, the porous substrate is suspended from the bottom of the container in the raw material aqueous solution. The material may be fixed. When the porous substrate is held vertically, a jig that can set the porous substrate vertically on the bottom of the container may be placed. In any case, LDH is substantially perpendicular to or close to the porous substrate (that is, the LDH plate-like particles have their plate surfaces intersecting the surface (substrate surface) of the porous substrate substantially perpendicularly or obliquely. It is preferable to adopt a configuration or arrangement in which growth is performed in such a direction. The raw material aqueous solution contains magnesium ions (Mg ²⁺ ) and aluminum ions (Al ³⁺ ) at a predetermined total concentration, and contains urea. By the presence of urea, ammonia is generated in the solution by utilizing hydrolysis of urea, so that the pH value increases, and the coexisting metal ions form hydroxides to obtain LDH. Further, since carbon dioxide is generated in the hydrolysis, LDH in which the anion is carbonate ion type can be obtained. The total concentration (Mg ²⁺ + Al ³⁺ ) of magnesium ions and aluminum ions contained in the raw material aqueous solution is preferably 0.20 to 0.40 mol / L, more preferably 0.22 to 0.38 mol / L, still more preferably 0.24 to 0.36 mol / L, particularly preferably 0.26 to 0.34 mol / L. When the concentration is within such a range, nucleation and crystal growth can proceed in a well-balanced manner, and an LDH-containing separator layer that is excellent not only in orientation but also in denseness can be obtained. That is, when the total concentration of magnesium ions and aluminum ions is low, crystal growth becomes dominant compared to nucleation, and the number of particles decreases and particle size increases. It is considered that the generation becomes dominant, the number of particles increases, and the particle size decreases.

Preferably, magnesium nitrate and aluminum nitrate are dissolved in the raw material aqueous solution, whereby the raw material aqueous solution contains nitrate ions in addition to magnesium ions and aluminum ions. In this case, the molar ratio (urea / NO ₃ ⁻ ) of urea to nitrate ions (NO ₃ ⁻ ) in the raw material aqueous solution is preferably 2 to 6, and more preferably 4 to 5.

(3) Formation of LDH-containing separator layer by hydrothermal treatment Then, the porous substrate is hydrothermally treated in the raw material aqueous solution to form a separator layer containing LDH on and / or in the porous substrate. . This hydrothermal treatment is preferably performed at 60 to 150 ° C. in a closed container, more preferably 65 to 120 ° C., still more preferably 65 to 100 ° C., and particularly preferably 70 to 90 ° C. The upper limit temperature of the hydrothermal treatment may be selected so that the porous substrate (for example, the polymer substrate) is not deformed by heat. The rate of temperature increase during the hydrothermal treatment is not particularly limited and may be, for example, 10 to 200 ° C./h, preferably 100 to 200 ° C./h, more preferably 100 to 150 ° C./h. The hydrothermal treatment time may be appropriately determined according to the target density and thickness of the LDH-containing separator layer.

  After the hydrothermal treatment, the porous substrate is preferably taken out from the sealed container and washed with ion exchange water.

  The LDH-containing separator layer in the LDH-containing composite material produced as described above is one in which LDH plate-like particles are highly densified and oriented in a substantially vertical direction advantageous for conduction. Therefore, it can be said that it is extremely suitable for a nickel zinc secondary battery in which the progress of zinc dendrite has become a major barrier to practical use.

  By the way, the LDH containing separator layer obtained by the said manufacturing method can be formed in both surfaces of a porous base material. For this reason, in order to make the LDH-containing composite material suitable for use as a separator, the LDH-containing separator layer on one side of the porous substrate is mechanically scraped after film formation, or on one side during film formation. It is desirable to take measures so that the LDH-containing separator layer cannot be formed.

  The present invention is more specifically described by the following examples.

Example 1 (Reference): Production and Evaluation of LDH Separator with Porous Base Material This example is a production example of a flat plate-like LDH separator with a porous base material. Therefore, although the separator produced in this example is not a cell container type separator, the cell container type separator according to the present invention can be obtained by forming the porous substrate and the separator into a cell container type while referring to the following production examples. It can be produced as appropriate.

(1) Production of porous substrate Boehmite (manufactured by Sasol, DISPAL 18N4-80), methylcellulose, and ion-exchanged water are mixed at a weight ratio of 10: 1: (boehmite) :( methylcellulose) :( ion-exchanged water). After weighing so as to be 5, kneaded. The obtained kneaded product was subjected to extrusion molding using a hand press and molded into a plate shape having a size sufficiently exceeding 5 cm × 8 cm and a thickness of 0.5 cm. The obtained molded body was dried at 80 ° C. for 12 hours and then calcined at 1150 ° C. for 3 hours to obtain an alumina porous substrate. The porous substrate thus obtained was cut into a size of 5 cm × 8 cm.

  With respect to the obtained porous substrate, the porosity on the surface of the porous substrate was measured by a technique using image processing, and it was 24.6%. The porosity is measured by 1) observing the surface microstructure using a scanning electron microscope (SEM, JSM-6610LV, manufactured by JEOL) at an acceleration voltage of 10 to 20 kV, and an electron microscope on the surface of the porous substrate ( SEM) image (magnification of 10,000 times or more) is obtained, 2) a grayscale SEM image is read using image analysis software such as Photoshop (manufactured by Adobe), etc. 3) [Image] → [Tone Correction] → [2 A monochrome binary image was created by the procedure of [gradation], and 4) the porosity (%) was obtained by dividing the number of pixels occupied by the black portion by the total number of pixels in the image. This porosity measurement was performed on a 6 μm × 6 μm region on the surface of the porous substrate. In addition, the SEM image of the porous base material surface is shown in FIG.

  Moreover, it was about 0.1 micrometer when the average hole diameter of the porous base material was measured. In the present invention, the average pore diameter was measured by measuring the longest distance of the pores based on an electron microscope (SEM) image of the surface of the porous substrate. The magnification of the electron microscope (SEM) image used for this measurement is 20000 times, and all the obtained pore diameters are arranged in order of size, and the top 15 points and the bottom 15 points from the average value, and 30 points per visual field in total. The average value for two visual fields was calculated to obtain the average pore diameter. For length measurement, the length measurement function of SEM software was used.

(2) Cleaning of porous substrate The obtained porous substrate was ultrasonically cleaned in acetone for 5 minutes, ultrasonically cleaned in ethanol for 2 minutes, and then ultrasonically cleaned in ion-exchanged water for 1 minute.

(3) As the manufacturing raw material of the raw aqueous solution, magnesium nitrate hexahydrate _{(Mg (NO 3) 2 ·} 6H 2 O, manufactured by Kanto Chemical Co., Inc.), aluminum nitrate nonahydrate (Al _{(NO 3)} 3 · 9H ₂ O, manufactured by Kanto Chemical Co., Ltd.) and urea ((NH ₂ ) ₂ CO, manufactured by Sigma-Aldrich) were prepared. Weigh magnesium nitrate hexahydrate and aluminum nitrate nonahydrate so that the cation ratio (Mg ²⁺ / Al ³⁺ ) is 2 and the total metal ion molar concentration (Mg ²⁺ + Al ³⁺ ) is 0.320 mol / L. In a beaker, ion exchange water was added to make a total volume of 600 ml. After stirring the obtained solution, urea weighed at a ratio of urea / NO ₃ ⁻ = 4 was added to the solution, and further stirred to obtain a raw material aqueous solution.

(4) Film formation by hydrothermal treatment The Teflon (registered trademark) sealed container (with an internal volume of 800 ml, the outside is a stainless steel jacket), the raw material aqueous solution prepared in (3) above and the porous substrate washed in (2) above Both were enclosed. At this time, the base material was fixed by being floated from the bottom of a Teflon (registered trademark) sealed container, and placed horizontally so that the solution was in contact with both surfaces of the base material. Thereafter, hydrothermal treatment was performed at a hydrothermal temperature of 70 ° C. for 168 hours (7 days) to form a layered double hydroxide alignment film (separator layer) on the substrate surface. After the elapse of a predetermined time, the substrate is taken out from the sealed container, washed with ion-exchanged water, dried at 70 ° C. for 10 hours, and a dense layer of layered double hydroxide (hereinafter referred to as LDH) (hereinafter referred to as a membrane sample). ) Was obtained on a substrate. The thickness of the obtained film sample was about 1.5 μm. Thus, a layered double hydroxide-containing composite material sample (hereinafter referred to as a composite material sample) was obtained. Although the LDH film was formed on both surfaces of the porous substrate, the LDH film on one surface of the porous substrate was mechanically scraped to give the composite material a form as a separator.

(5) Various evaluations (5a) Identification of film sample Film sample with X-ray diffractometer (RINT TTR III manufactured by Rigaku Corporation) under the measurement conditions of voltage: 50 kV, current value: 300 mA, measurement range: 10-70 ° When the crystal phase of was measured, the XRD profile shown in FIG. 7 was obtained. About the obtained XRD profile, JCPDS card NO. It identified using the diffraction peak of the layered double hydroxide (hydrotalcite compound) described in 35-0964. As a result, it was confirmed that the film sample was a layered double hydroxide (LDH, hydrotalcite compound). In addition, in the XRD profile shown in FIG. 7, a peak (a peak marked with a circle in the figure) due to alumina constituting the porous substrate on which the film sample is formed is also observed. .

(5b) Observation of microstructure The surface microstructure of the film sample was observed at an acceleration voltage of 10 to 20 kV using a scanning electron microscope (SEM, JSM-6610LV, manufactured by JEOL). FIG. 8 shows an SEM image (secondary electron image) of the surface microstructure of the obtained film sample.

  Further, the cross section of the composite material sample was polished by CP polishing to form a polished cross section, and the microstructure of the polished cross section was observed at an acceleration voltage of 10 to 20 kV using a scanning electron microscope (SEM). FIG. 9 shows an SEM image of the polished cross-sectional microstructure of the composite material sample thus obtained.

(5c) Measurement of porosity The porosity of the surface of the membrane was measured for the membrane sample by a technique using image processing. The porosity is measured by 1) observing the surface microstructure using a scanning electron microscope (SEM, JSM-6610LV, manufactured by JEOL) at an acceleration voltage of 10 to 20 kV, and an electron microscope (SEM) on the surface of the film. An image (magnification of 10,000 times or more) is acquired, 2) a grayscale SEM image is read using image analysis software such as Photoshop (manufactured by Adobe), and 3) [image] → [tone correction] → [2 gradations] A black and white binary image was created by the procedure of 4), and 4) the value obtained by dividing the number of pixels occupied by the black portion by the total number of pixels of the image was taken as the porosity (%). This porosity measurement was performed on a 6 μm × 6 μm region of the alignment film surface. As a result, the porosity of the film surface was 19.0%. Further, using the porosity of the film surface, the density D when viewed from the film surface (hereinafter referred to as the surface film density) was calculated by D = 100% − (porosity of the film surface). %Met.

  Further, the porosity of the polished cross section of the film sample was also measured. The measurement of the porosity of the polished cross section is the same as that described above except that an electron microscope (SEM) image (magnification of 10,000 times or more) of the cross-section polished surface in the thickness direction of the film was obtained according to the procedure shown in (5b) above. It carried out similarly to the porosity of the film | membrane surface. The measurement of the porosity was performed on the film portion of the alignment film cross section. Thus, the porosity calculated from the cross-sectional polished surface of the film sample is 3.5% on average (average value of the three cross-sectional polished surfaces), and a very high-density film is formed on the porous substrate. It was confirmed that

(5d) Denseness determination test I
In order to confirm that the membrane sample has a denseness that does not have water permeability, a denseness determination test was performed as follows. First, as shown in FIG. 10A, the composite material sample 220 obtained in (1) above (cut to 1 cm × 1 cm square) has a center of 0.5 cm × 0.5 cm square on the film sample side. The silicon rubber 222 provided with the opening 222a was bonded, and the obtained laminate was bonded between two acrylic containers 224 and 226. The bottom of the acrylic container 224 disposed on the silicon rubber 222 side is removed, and thereby the silicon rubber 222 is bonded to the acrylic container 224 with the opening 222a opened. On the other hand, the acrylic container 226 disposed on the porous substrate side of the composite material sample 220 has a bottom, and ion-exchanged water 228 is contained in the container 226. At this time, Al and / or Mg may be dissolved in the ion exchange water. That is, by assembling the components upside down after assembly, the constituent members are arranged so that the ion-exchanged water 228 is in contact with the porous substrate side of the composite material sample 220. After assembling these components, the total weight was measured. After assembling these components, the total weight was measured. Needless to say, the container 226 has a closed vent hole (not shown) and is opened after being turned upside down. As shown in FIG. 10B, the assembly was placed upside down and held at 25 ° C. for 1 week, after which the total weight was measured again. At this time, when water droplets adhered to the inner side surface of the acrylic container 224, the water droplets were wiped off. Then, the density was determined by calculating the difference in the total weight before and after the test. As a result, no change was observed in the weight of ion-exchanged water even after holding at 25 ° C. for 1 week. From this, it was confirmed that the membrane sample (that is, the functional membrane) has high density so as not to have water permeability.

(5e) Denseness determination test II
In order to confirm that the film sample has a denseness that does not have air permeability, a denseness determination test was performed as follows. First, as shown in FIGS. 11A and 11B, an acrylic container 230 without a lid and an alumina jig 232 having a shape and size that can function as a lid for the acrylic container 230 were prepared. The acrylic container 230 is formed with a gas supply port 230a for supplying gas therein. The alumina jig 232 has an opening 232a having a diameter of 5 mm, and a depression 232b for placing a film sample is formed along the outer periphery of the opening 232a. An epoxy adhesive 234 was applied to the depression 232b of the alumina jig 232, and the film sample 236b side of the composite material sample 236 was placed in the depression 232b to adhere to the alumina jig 232 in an airtight and liquid-tight manner. Then, the alumina jig 232 to which the composite material sample 236 is bonded is adhered to the upper end of the acrylic container 230 in a gas-tight and liquid-tight manner using a silicone adhesive 238 so as to completely close the opening of the acrylic container 230. A measurement sealed container 240 was obtained. The measurement sealed container 240 was placed in a water tank 242, and the gas supply port 230 a of the acrylic container 230 was connected to the pressure gauge 244 and the flow meter 246 so that helium gas could be supplied into the acrylic container 230. Water 243 was put into the water tank 242 and the measurement sealed container 240 was completely submerged. At this time, the inside of the measurement sealed container 240 is sufficiently airtight and liquid-tight, and the membrane sample 236b side of the composite material sample 236 is exposed to the internal space of the measurement sealed container 240, while the composite material sample The porous base material 236 a side of 236 is in contact with the water in the water tank 242. In this state, helium gas was introduced into the measurement sealed container 240 into the acrylic container 230 via the gas supply port 230a. The pressure gauge 244 and the flow meter 246 are controlled so that the differential pressure inside and outside the membrane sample 236b is 0.5 atm (that is, the pressure applied to the side in contact with the helium gas is 0.5 atm higher than the water pressure applied to the opposite side). Whether or not helium gas bubbles are generated in the water from the composite material sample 236 was observed. As a result, generation of bubbles due to helium gas was not observed. Therefore, it was confirmed that the membrane sample 236b has high density so as not to have air permeability.

Example 2 (Reference): Production of Zinc-Air Secondary Battery This example is a reference example of a zinc-air secondary battery using a flat plate-like LDH separator with a porous substrate. Therefore, although the battery produced in this example is not a battery equipped with a cell container type separator, an air electrode, a negative electrode, By disposing a current collector or the like, the battery according to the present invention can be appropriately manufactured while referring to the following manufacturing examples as necessary.

(1) Preparation of separator with porous substrate A hydrotalcite film on an alumina substrate was prepared as a separator with a porous substrate (hereinafter simply referred to as a separator) by the same procedure as in Example 1.

(2) Production of air electrode layer α-MnO ₂ particles as an air electrode catalyst were produced as follows. First, Mn (SO ₄ ) · 5H ₂ O and KMnO ₄ were dissolved in deionized water at a molar ratio of 5:13 and mixed. The obtained mixed liquid is put into a stainless steel sealed container with Teflon (registered trademark) attached thereto, and hydrothermal synthesis is performed at 140 ° C. for 2 hours. The precipitate obtained by hydrothermal synthesis was filtered, washed with distilled water, and dried at 80 ° C. for 6 hours. In this way, α-MnO ₂ powder was obtained.

Layered double hydroxide particles (hereinafter referred to as LDH particles) as hydroxide ion conductive materials were produced as follows. First, Ni (NO ₃ ) ₂ · 6H ₂ O and Fe (NO ₃ ) ₃ · 9H ₂ O were dissolved and mixed in deionized water to a molar ratio of Ni: Fe = 3: 1. The resulting mixture was added dropwise to a 0.3 M Na ₂ CO ₃ solution at 70 ° C. with stirring. At this time, the pH of the mixed solution is adjusted to 10 while adding a 2M NaOH solution and maintained at 70 ° C. for 24 hours. The precipitate formed in the mixed solution was filtered, washed with distilled water, and then dried at 80 ° C. to obtain LDH powder.

The α-MnO ₂ particles and LDH particles obtained earlier and carbon black (product number VXC72, manufactured by Cabot Co., Ltd.) as an electron conductive material are weighed so as to have a predetermined blending ratio, and in the presence of an ethanol solvent. Wet mixed. The resulting mixture is dried at 70 ° C. and then crushed. The obtained pulverized powder was mixed with a binder (PTFE, manufactured by Electrochem, product number EC-TEF-500ML) and water for fibrillation. At this time, the amount of water added was 1% by mass with respect to the air electrode. The fibrillar mixture thus obtained was pressure-bonded to a current collector (carbon cloth (manufactured by Electrochem, product number EC-CC1-060T)) in a sheet form so as to have a thickness of 50 μm, and the air electrode layer / current collector A laminated sheet was obtained. The air electrode layer thus obtained has an electron conductive phase (carbon black) of 20% by volume, a catalyst layer (α-MnO ₂ particles) of 5% by volume, a hydroxide ion conductive phase (LDH particles) of 70% by volume and It contained 5% by volume of a binder phase (PTFE).

(3) Production of air electrode with separator An anion exchange membrane (Astom Corp., Neocepta AHA) was immersed in 1M NaOH aqueous solution overnight. This anion exchange membrane is laminated as an intermediate layer on the hydrotalcite membrane of the separator to obtain a separator / intermediate layer laminate. The thickness of the intermediate layer is 30 μm. The separator / intermediate layer laminate thus obtained is pressure-bonded with the air electrode layer / current collector laminated sheet prepared previously so that the air electrode layer side is in contact with the intermediate layer, thereby obtaining an air electrode sample with a separator.

(4) Production of Negative Electrode Plate A mixture of 80 parts by weight of zinc oxide powder, 20 parts by weight of zinc powder and 3 parts by weight of polytetrafluoroethylene particles was applied onto a current collector made of copper punching metal, and the porosity was about A negative electrode plate coated with an active material portion at 50% is obtained.

(5) Production of third electrode A platinum paste is applied on a current collector made of nickel mesh to obtain a third electrode.

(6) Assembly of battery Using the obtained air electrode with separator, negative electrode plate, and third electrode, a zinc-air secondary battery having a horizontal structure is manufactured in the following procedure. First, a container without a lid (hereinafter referred to as a resin container) made of ABS resin and having a rectangular parallelepiped shape is prepared. The negative electrode plate is placed on the bottom of the resin container so that the side on which the negative electrode active material is coated faces upward. At this time, the negative electrode current collector is in contact with the bottom of the resin container, and the end of the negative electrode current collector is connected to an external terminal provided through the side surface of the resin container. Next, a third electrode is provided at a position higher than the upper surface of the negative electrode plate on the inner wall of the resin container (that is, a position that does not contact the negative electrode plate and does not participate in the charge / discharge reaction), and the nonwoven fabric separator contacts the third electrode. Deploy. The opening of the resin container is closed with an air electrode with a separator so that the air electrode side is on the outside. At that time, an epoxy resin-based adhesive (EP008, manufactured by Cemedine Co., Ltd.) is applied to the outer peripheral portion of the opening to Seal and bond to give liquid tightness. A 6 mol / L aqueous solution of KOH is injected as an electrolyte into the resin container through a small inlet provided near the upper end of the resin container. In this way, the separator comes into contact with the electrolyte solution, and the electrolyte solution can always contact the third electrode regardless of the increase or decrease of the electrolyte solution due to the liquid retaining property of the nonwoven fabric separator. At this time, the amount of electrolyte to be injected is the amount of water expected not only to sufficiently hide the negative electrode active material coating part in the resin container but also to decrease during charging in order to produce a battery in a discharged state. Use an excess amount in consideration. Therefore, the resin container is designed so as to accommodate the excessive amount of the electrolytic solution. Finally, the inlet of the resin container is sealed. Thus, the internal space defined by the resin container and the separator is hermetically and liquid-tightly sealed. Finally, the third electrode and the current collecting layer of the air electrode are connected via an external circuit. In this way, a zinc-air secondary battery is obtained.

  According to such a configuration, since the separator has a high degree of denseness that does not allow water and gas to pass through, the penetration of the separator by the zinc dendrite generated during charging is physically blocked to prevent a short circuit between the positive and negative electrodes, In addition, it is possible to prevent the infiltration of carbon dioxide in the air and to prevent the precipitation of alkali carbonate (caused by carbon dioxide) in the electrolyte. In addition, hydrogen gas that can be generated by a side reaction from the negative electrode can be brought into contact with the third electrode and returned to water through the above-described reaction. That is, a highly reliable zinc-air secondary battery that can cope with the problem of hydrogen gas generation while having a configuration suitable for preventing both short-circuiting due to zinc dendrite and mixing of carbon dioxide is provided. .

DESCRIPTION OF SYMBOLS 10 Zinc air battery 12 Air electrode 16 Negative electrode 17 Negative electrode collector 20 Separator 22 Battery container 24 Air electrode chamber 26 Negative electrode chamber 120 Separator layer 128 Porous base material

Claims (20)

An air electrode as a positive electrode;
A negative electrode comprising zinc, a zinc alloy and / or a zinc compound;
An electrolyte containing an aqueous alkali metal hydroxide solution in which the negative electrode is immersed;
A separator that is provided to partition the air electrode chamber that accommodates the air electrode and the negative electrode chamber that accommodates the negative electrode and the electrolyte, and has hydroxide ion conductivity but does not have water permeability and air permeability; ,
A battery container containing the air electrode, the negative electrode, the electrolytic solution, and the separator;
A zinc-air battery comprising:
The separator is a cell container type separator having a cell container shape, whereby the air electrode is accommodated in the cell container type separator, and the negative electrode and the electrolysis are included in the battery container outside the cell container type separator. Liquid is contained, or the negative electrode and the electrolytic solution are contained in the cell container type separator and the air electrode is contained in the battery container outside the cell container type separator,
A zinc-air battery, wherein the air electrode chamber is opened to the outside air, and the negative electrode chamber is a sealed space formed by the battery container type separator and the battery container and / or a sealing member.   The zinc-air battery according to claim 1, wherein the cell container type separator has a bag tubular shape, a tubular shape, a box shape, or a bag shape.   The air electrode is accommodated in the cell container type separator along the inner wall of the cell container type separator, and the negative electrode and the electrolytic solution are accommodated in the battery container outside the cell container type separator. The zinc-air battery according to claim 1 or 2.   The negative electrode and the electrolytic solution are accommodated in the cell container type separator, and the air electrode is accommodated in a form along the outer wall of the cell container type separator in the battery container outside the cell container type separator. The zinc-air battery according to claim 1 or 2.   The zinc-air battery according to any one of claims 1 to 4, wherein the negative electrode chamber has a surplus space having a volume that allows a decrease in water amount associated with a negative electrode reaction during charging and discharging.   The zinc-air battery according to claim 5, wherein the cell container type separator is provided vertically, and the negative electrode chamber has the excess space above it.   The zinc-air battery according to any one of claims 1 to 6, wherein the cell container separator is made of an inorganic solid electrolyte body.   The zinc-air battery according to claim 7, wherein the inorganic solid electrolyte body has a relative density of 90% or more. The inorganic solid electrolyte body has the general formula:
^{_{M 2+ 1-x M 3+ x}} (OH) 2 A n- x / n · mH 2 O
^{(Wherein, M 2+} is a divalent ^{cation, M 3+} is a trivalent ^{cation, A n-is} the n-valent anion, n is an integer of 1 or more, x is 0 0.1 to 0.4, and m is 0 or more)
The zinc-air battery according to claim 7 or 8, comprising a layered double hydroxide having a basic composition of: In the general ^{formula, M 2+} comprises ^{Mg 2+,} include ^{M 3+} is ^{Al 3+, A n-is} OH ^- and / or _CO containing ^{3 2-,} zinc-air battery according to claim 9.   The zinc-air battery according to any one of claims 7 to 10, wherein the inorganic solid electrolyte body has a plate shape, a film shape, or a layer shape.   The cell container type porous substrate further comprising a cell container shape having a cell container shape compatible with the cell container type separator on the surface of the negative electrode side of the cell container type separator. Zinc-air battery.   The zinc according to claim 12, wherein the inorganic solid electrolyte body is in the form of a film or a layer, and the film or layered inorganic solid electrolyte is formed on or in the porous substrate. Air battery.   The zinc-air battery according to any one of claims 7 to 13, wherein the inorganic solid electrolyte body is densified by hydrothermal treatment.   The zinc-air battery according to any one of claims 1 to 14, wherein the alkali metal hydroxide is potassium hydroxide.   The zinc-air battery further comprises a breathable air electrode current collector provided in contact with the air electrode, and a negative electrode current collector provided in contact with the negative electrode. The zinc-air battery according to any one of 15.   The battery container is composed of a breathable air electrode current collector, whereby the air electrode current collector is in contact with the air electrode, and the zinc-air battery is in contact with the negative electrode. The zinc-air battery according to any one of claims 4 to 15, further comprising a negative electrode current collector provided.   The zinc-air battery includes a third electrode provided so as to be in contact with the electrolyte but not in contact with the negative electrode, and the third electrode is connected to the air electrode via an external circuit. The zinc-air battery according to any one of 1 to 17.   The zinc-air battery according to any one of claims 1 to 18, wherein a plurality of the zinc-air batteries are spaced apart from each other in an assembled battery container. A plurality of the cell container type separators are disposed in the battery container so as to be separated from each other, and the negative electrode and the electrolyte solution or the air electrode are accommodated in each of the plurality of the cell container type separators. The zinc-air battery according to any one of claims 1 to 18.