JP2016201199A - Secondary battery using hydroxide ion conductivity ceramics separator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a secondary battery including a plurality of unit batteries with good space efficiency, while isolating between positive and negative electrodes reliably by a hydroxide ion conductivity ceramics separator.SOLUTION: A secondary battery includes a columnar porous base material including a plurality of cell holes provided in parallel from a first end face toward a second end face and/or from the second end face toward the first end face, positive electrodes and negative electrodes disposed in the plurality of cell holes alternately for each cell hole or hole array, a positive electrode internal collector inserted into the positive electrode, and extending to the first end face or the outer peripheral surface, a negative electrode internal collector inserted into the negative electrode, and extending to the second end face or the outer peripheral surface, a hydroxide ion conductivity ceramics separator formed on the inner wall surface of the cell hole, and isolating the positive electrode and/or negative electrode from the porous base material, and an electrolyte.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a secondary battery using a hydroxide ion conductive ceramic separator.

  Although zinc secondary batteries such as nickel-zinc secondary batteries and zinc-air secondary batteries have been developed and studied for a long time, they have not yet been put into practical use. This is because the zinc constituting the negative electrode produces dendritic crystals called dendrite during charging, and this dendrite breaks through the separator and causes a short circuit with the positive electrode. Therefore, a technique for preventing a short circuit due to zinc dendrite in a zinc secondary battery such as a nickel zinc secondary battery or a zinc-air secondary battery is strongly desired.

In order to deal with such problems and demands, a battery using a hydroxide ion conductive ceramic separator has been proposed. For example, in Patent Document 1 (International Publication No. 2013/118561), a separator made of a hydroxide ion conductive inorganic solid electrolyte is used as a positive electrode in a nickel zinc secondary battery for the purpose of preventing a short circuit due to zinc dendrite. And an inorganic solid electrolyte body having a general formula: M ²⁺ _1-x M ³⁺ _x (OH) ₂ A ⁿ⁻ _{x / n} · mH ₂ O (wherein M ²⁺ is at least is at least one divalent cation, M ³⁺ is at least one or more trivalent cations, a ^n-is the n-valent anion, n represents an integer of 1 or more, x is 0 It is proposed to use a layered double hydroxide (LDH) having a basic composition of. Further, in Patent Document 2 (International Publication No. 2013/073292), in a zinc-air secondary battery, a separator made of layered double hydroxide (LDH) having the same basic composition as described above is brought into close contact with one side of the air electrode. It has been proposed that both the short circuit between the positive and negative electrodes due to zinc dendrite during charging and the mixing of carbon dioxide into the electrolyte can be prevented.

  On the other hand, in order to obtain a high voltage and a large current, a laminated battery made by combining a plurality of unit batteries is widely known. A laminated battery has a configuration in which a laminated body formed by connecting a plurality of unit batteries in series or in parallel is accommodated in one battery container.

International Publication No. 2013/118561 International Publication No. 2013/073292

  The present applicant has succeeded in developing an LDH separator (layered double hydroxide separator) that has hydroxide ion conductivity but is highly densified to such an extent that it does not have water permeability and air permeability. When such a separator (or a separator with a porous substrate) is used to form a secondary battery such as a zinc-nickel battery or a zinc-air secondary battery, a short circuit due to zinc dendrite (especially in the case of a metal-air secondary battery) (Problem) carbon dioxide contamination can be prevented. In order to maximize this effect, it is desired to reliably partition the positive electrode side and the negative electrode side in the battery container with a hydroxide ion conductive ceramic separator. In particular, it is extremely advantageous if a battery in which a plurality of (preferably a large number) unit cells are incorporated in a space efficient manner can be obtained in order to obtain a high voltage and a large current while securing such a configuration.

  The present inventors recently used a columnar porous substrate having a plurality of cell holes provided in parallel to each other in a predetermined direction, and provided hydroxide ion conductive ceramic separators on the inner wall surfaces of the cell holes. Obtaining the knowledge that by forming a positive electrode and / or a negative electrode after formation, a secondary battery in which a plurality of unit cells are incorporated in a space-efficient manner can be obtained while reliably separating the positive and negative electrodes with a separator. It was. In particular, such a battery structure has been found to be extremely advantageous in terms of securing high strength, increasing output by increasing the reaction area, and facilitating current collection.

  Accordingly, an object of the present invention is to provide a secondary battery provided with a plurality of unit batteries with good space efficiency while reliably separating positive and negative electrodes with a hydroxide ion conductive ceramic separator.

According to one aspect of the present invention, a secondary battery using a hydroxide ion conductive ceramic separator,
A columnar porous substrate having a first end surface and a second end surface facing each other and an outer peripheral surface connecting outer peripheral edges of these end surfaces, and from the first end surface toward the second end surface and / or A porous substrate provided with a plurality of cell holes provided in parallel to each other from the second end surface toward the first end surface;
A positive electrode and a negative electrode that are alternately arranged in the plurality of cell holes for each hole or for each hole row;
A positive electrode internal current collector inserted into the positive electrode and extending to the first end surface or the outer peripheral surface;
A negative electrode internal current collector inserted into the negative electrode and extending to the second end surface, the outer peripheral surface or the first end surface;
A hydroxide ion conductive ceramic separator formed on an inner wall surface of the cell hole and separating the positive electrode and / or the negative electrode from the porous substrate;
An alkaline electrolyte impregnated in the positive electrode and / or the negative electrode and the porous substrate;
A secondary battery is provided.

1 is a perspective view schematically showing an example of a nickel-zinc secondary battery having a honeycomb structure according to the present invention. 1 is a perspective view schematically showing an example of a zinc-air secondary battery having a honeycomb structure according to the present invention. It is a perspective view which shows typically an example of the nickel zinc secondary battery of the monolith structure by this invention. It is a perspective view which shows typically an example of the zinc air secondary battery of the monolith structure by this invention. It is a perspective view which shows typically another example of the nickel zinc secondary battery of the monolith structure by this invention. It is a perspective view which shows typically another example of the zinc air secondary battery of the monolith structure by this invention. It is a conceptual diagram which shows an example of a nickel zinc secondary battery typically, and shows a discharge end state. It is a figure which shows the full charge state of the nickel zinc secondary battery shown by FIG. It is a conceptual diagram which shows an example of a zinc air secondary battery typically. FIG. 9B is a perspective view of the zinc-air secondary battery shown in FIG. 9A. It is a schematic cross section showing one mode of a separator with a porous substrate. It is a schematic cross section which shows the other one aspect | mode of a separator with a porous base material. 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.

Secondary battery The secondary battery of the present invention uses a hydroxide ion conductive ceramic separator. The secondary battery of the present invention includes a nickel zinc secondary battery, a silver zinc oxide secondary battery, a manganese zinc secondary battery, a zinc air secondary battery, various other alkaline zinc secondary batteries, and a lithium air secondary battery. And various secondary batteries to which a hydroxide ion conductive ceramic separator can be applied. In particular, a nickel zinc secondary battery and a zinc-air secondary battery are preferable. Therefore, in the following general description, reference may be made to FIGS. 1, 3 and 5 relating to nickel-zinc secondary batteries and FIGS. 2, 4 and 6 relating to zinc-air secondary batteries. The present invention should not be limited to zinc secondary batteries and zinc-air secondary batteries, but conceptually includes the various secondary batteries described above that can employ hydroxide ion conductive ceramic separators.

  The secondary battery according to the present invention includes a porous substrate, a positive electrode, a negative electrode, a positive electrode internal current collector, a negative electrode internal current collector, a hydroxide ion conductive ceramic separator, and an alkaline electrolyte. The porous substrate has a columnar shape (for example, a columnar shape or a prismatic shape), and includes a first end surface and a second end surface facing each other, and an outer peripheral surface connecting the outer peripheral edges of these end surfaces. The porous substrate includes a plurality of cell holes provided in parallel to each other from the first end surface toward the second end surface and / or from the second end surface toward the first end surface. The positive electrode and the negative electrode are alternately arranged in the plurality of cell holes for each hole or for each hole row. The positive electrode internal current collector is inserted into the positive electrode and extends to the first end surface or the outer peripheral surface. On the other hand, the negative electrode internal current collector is inserted into the negative electrode and extends to the second end surface, the outer peripheral surface or the first end surface. The hydroxide ion conductive ceramic separator is formed on the inner wall surface of the cell hole and isolates the positive electrode and / or the negative electrode from the porous substrate. The positive electrode and / or negative electrode and the porous substrate are impregnated with an alkaline electrolyte. In this way, after using a columnar porous substrate having a plurality of cell holes provided in parallel to each other in a predetermined direction, a hydroxide ion conductive ceramic separator is formed on the inner wall surface of the cell holes. By disposing the positive electrode and / or the negative electrode, it is possible to configure a secondary battery in which a plurality of unit batteries are incorporated with good space efficiency while reliably separating the positive and negative electrodes with a separator. In particular, such a battery structure is extremely advantageous in terms of ensuring high strength, increasing output by increasing the reaction area, and facilitating current collection. That is, since the columnar porous substrate can have a solidity as a lump or a bulk, it is easy to ensure high strength. Therefore, a large number of cell holes can be provided in the porous base material, and a large number of electrodes and internal current collectors can be disposed, whereby the reaction area can be dramatically increased. In addition, by forming the cell holes with a desired regularity, an internal current collector corresponding to a desired electrode up to both end faces (that is, the first end face and the second end face) of the porous member and other outer peripheral faces The external current collector is also easily disposed in the extended portion. That is, it becomes the structure which is easy to collect current.

  The positive electrode and the negative electrode are alternately arranged in the plurality of cell holes for each hole or for each hole row. The positive electrode may be appropriately selected according to the type of secondary battery, and may be an air electrode. The negative electrode may be appropriately selected according to the type of secondary battery. For example, in the case of various zinc secondary batteries, zinc, a zinc alloy, and / or a zinc compound may be included. In this case, the positive electrode preferably comprises nickel hydroxide and / or nickel oxyhydroxide, whereby the secondary battery is configured as a nickel zinc secondary battery. Alternatively, it is also preferable that the positive electrode is an air electrode, and the positive electrode internal current collector and optionally the positive electrode external current collector have air permeability, whereby the secondary battery is configured as a zinc-air secondary battery. The positive electrode and / or negative electrode impregnated with the alkaline electrolyte and the porous substrate can be accommodated in a container (preferably a resin container). It should be noted that the positive electrode and the alkaline electrolyte need not necessarily be separated, and may be configured as a positive electrode mixture in which the positive electrode and the alkaline electrolyte are mixed. No liquid is required. Moreover, the negative electrode and the alkaline electrolyte need not necessarily be separated, and may be configured as a negative electrode mixture in which the negative electrode and the alkaline electrolyte are mixed.

  The positive electrode internal current collector is inserted into the positive electrode and extends to the first end surface or the outer peripheral surface. The negative electrode internal current collector is inserted into the negative electrode and extends to the second end surface, the outer peripheral surface, or the first end surface. That is, the positive electrode internal current collector and the negative electrode internal current collector may extend to different surfaces (for example, the first end surface and the second end surface) or different positions (for example, different sides of the outer peripheral surface), As long as they are not short-circuited with each other, they may extend to the same end face (for example, the first end face). However, it is easy to collect current because the positive electrode internal current collector and the negative electrode internal current collector extend to different surfaces or positions, and it is easy to secure a space for arranging the external current collector. This is preferable.

  The porous substrate has a columnar shape (for example, a columnar shape or a prismatic shape), and includes a first end surface and a second end surface facing each other and an outer peripheral surface connecting the outer peripheral edges of these end surfaces. That is, it can be said that the outer surface of the porous substrate is mainly composed of the first end surface, the second end surface, and the outer peripheral surface. The porous substrate is provided with a plurality of cell holes provided in parallel to each other from the first end surface toward the second end surface and / or from the second end surface toward the first end surface. The cell hole may be a through hole or a non-through hole. In addition, one end of the through hole may be sealed with a sealing member (for example, ceramics or resin) to result in a non-through hole. In this case, the hole is treated as a non-through hole in the following description. To do. In the case of a through-hole, the plurality of formed cell holes provided in parallel with each other from the first end surface toward the second end surface are a plurality of cells provided in parallel with each other from the second end surface toward the first end surface. It will refer to the same thing as the hole. In the case of a non-through hole, a plurality of cell holes provided in parallel with each other from the first end face toward the second end face, and a plurality of cell holes provided in parallel with each other from the second end face toward the first end face The non-through hole opened on the first end face side and the non-through hole opened on the second end face side are respectively assigned to the positive electrode and the negative electrode, and the positive electrode current collector and the negative electrode current collector are provided. Is preferable in that it can be extended to opposite sides. However, the plurality of cell holes may be configured by only a plurality of non-through holes provided in parallel to each other from the first end surface to the second end surface, or parallel to each other from the second end surface to the first end surface. However, in these cases, all the non-through holes are opened to the same side, and as a result, the positive electrode current collector and the negative electrode current collector are It will extend to the same side. In any case, as described above, since the columnar porous base material can have a unity as a lump or bulk, ensuring high strength, increasing the output by increasing the reaction area, and facilitating current collection, etc. This makes it possible to realize a secondary battery structure that is extremely advantageous. It goes without saying that the porous substrate is water permeable, so that the alkaline electrolyte can reach the separator, but the presence of the porous substrate keeps hydroxide ions more stable on the separator. It is also possible to do. In addition, since the strength can be imparted by the porous base material, the resistance can be reduced by thinning the separator. A dense film or a dense layer of an inorganic solid electrolyte body (preferably LDH) can be formed as a hydroxide ion conductive ceramic separator on the inner wall surface of the cell hole of the porous substrate.

  According to a preferred aspect of the present invention, the cell holes can be non-through holes, and the porous substrate can have a honeycomb shape regularly provided with a plurality of non-through holes. An example of a nickel zinc secondary battery according to this embodiment is schematically shown in FIG. In FIG. 1, a nickel-zinc secondary battery 10 has a cylindrical porous substrate 12, and the porous substrate 12 is provided in parallel to each other from the first end surface 12a to the second end surface 12b. A plurality of non-through holes 12d and a plurality of non-through holes 12e provided in parallel to each other from the second end surface 12b toward the first end surface 12a are provided. The positive electrode 14 and the negative electrode 16 are alternately disposed in each of the plurality of non-through holes 12d and 12e. The plurality of non-through holes 12d and 12e are regularly formed, so that the porous substrate 12 has a honeycomb shape. The hydroxide ion conductive ceramic separator 18 may be formed on the inner wall surface of all the non-through holes 12d and 12e. However, as shown in FIG. 1, the hydroxide ion conductive ceramic separator 18 is formed on the inner wall surface of the non-through hole 12d in which the positive electrode 14 is accommodated. May be formed only on the inner wall surface of the non-through hole 12e in which the negative electrode 16 is accommodated. In any case, in such a honeycomb structure, the positive electrode 14 and the positive electrode internal current collector 15a are accommodated in the non-through hole 12d formed from the first end surface 12a to the second end surface 12b of the porous substrate 12. The negative electrode 16 and the negative electrode internal current collector 17a are accommodated in the non-through hole 12e formed from the second end surface 12b toward the first end surface 12a, whereby the positive electrode internal current collector 15a and the negative electrode internal current collector are accommodated. It is preferable that 17a is extended to the end surfaces 12a and 12b opposite to each other. In this way, the positive electrode 14 and the negative electrode 16 are accommodated in the non-through holes 12d and 12e that are opened on different sides, thereby reliably preventing a short circuit between the positive and negative electrodes, and providing a large number of the positive electrodes 14 and the negative electrodes 16. Thus, the reaction area can be remarkably increased and high output can be realized. Further, since the positive electrode internal current collector 15a and the negative electrode internal current collector 17a extend to the end faces 12a and 12b opposite to each other, current collection is easy. In this regard, the positive electrode external current collector 15b connected to the end portions of the plurality of positive electrode internal current collectors 15a is provided on the first end surface 12a, and the negative electrode external current collector connected to the end portions of the plurality of negative electrode internal current collectors 16a. It is more preferable to provide the electric body 16b on the second end face 12b in that the current collecting ability can be further enhanced. Further, the positive electrode external current collector 15b and the negative electrode external current collector 16b are formed in shapes corresponding to the first end surface 12a and the second end surface 12b, respectively, so that the first end surface 12a and the second end surface 12b are respectively connected to the positive electrode external current collector. It is particularly preferable that the electrode 15b and the negative electrode external current collector 16b are closed.

  The secondary battery having the honeycomb structure is not limited to the nickel-zinc secondary battery 10 shown in FIG. 1 but can be applied to other types of zinc secondary batteries. For example, in the case of a zinc-air secondary battery, the positive electrode current collector is preferably configured to have air permeability so that air can reach the positive electrode. An example of the zinc-air secondary battery having such a honeycomb structure is shown in FIG. A zinc-air secondary battery 20 having a honeycomb structure shown in FIG. 2 has a cylindrical porous substrate 22, a negative electrode 26, a negative electrode internal current collector 27a, and a negative electrode external current collector 27b shown in FIG. The porous substrate 12, the negative electrode 16, the negative electrode internal current collector 17 a, and the negative electrode external current collector 17 b can be configured in the same manner, but the air electrode 24 as the positive electrode, the positive electrode internal current collector 25 a, and the positive electrode external current collector Unlike the one shown in FIG. 1, 25 b is desirably configured so that air can be supplied to the air electrode 24 from the outside. The hydroxide ion conductive ceramic separator 28 may be formed on the inner wall surface of all the non-through holes 22d and 22e, or the inner wall surface of the non-through hole 22d in which the air electrode 24 is accommodated as shown in FIG. It may be formed only on. In any case, as shown in FIG. 2, it is preferable that the positive electrode internal current collector 25a has a breathable structure such as a hollow shape or a foam structure so that air from the outside can flow in. In this case, the positive electrode external current collector 25b connected to the positive electrode internal current collector 25a is formed with a vent 25c that communicates with the air-permeable structure such as a hollow shape or a foamed structure of the positive electrode internal current collector 25a. desirable. According to this configuration, it is possible to efficiently supply air to the air electrode 24 while ensuring a sufficient current collecting function. Further, the positive electrode external current collector 25b and the negative electrode external current collector 26b have shapes corresponding to the first end surface 22a and the second end surface 22b, respectively, except that the vent hole 25c is formed in the positive electrode external current collector 25b. It is particularly preferable that the portion other than the non-through hole 22d of the first end surface 22a and the second end surface 22b are respectively closed by the positive electrode external current collector 25b and the negative electrode external current collector 26b.

  According to another preferable aspect of the present invention, the cell hole may be a through hole, and the porous substrate may have a monolithic shape having a plurality of through holes regularly. An example of the nickel zinc secondary battery according to this embodiment is schematically shown in FIG. The nickel zinc secondary battery 30 shown in FIG. 3 has a prismatic porous base material 32, and this porous base material 32 is directed from the first end face 32a toward the second end face 32b (or the second end face). A plurality of through holes 32d provided in parallel to each other (from the end surface 32b toward the first end surface 32a) are provided. The positive electrode 34 and the negative electrode 36 are alternately arranged for each hole in the plurality of through holes 32d. The porous base material 32 is formed into a monolith by regularly forming the plurality of non-through holes 32d. The hydroxide ion conductive ceramic separator 38 may be formed on the inner wall surface of all the through holes 32d, but is formed only on the inner wall surface of the through hole 32d in which the positive electrode 34 is accommodated as shown in FIG. Alternatively, it may be formed only on the inner wall surface of the through hole 32d in which the negative electrode 36 is accommodated. In any case, in such a monolith configuration, the positive electrode internal current collector 35 a inserted into the positive electrode 34 extends to the outer peripheral surface 32 c via the slit 32 e formed in the porous base material 32, and It is preferable that the negative electrode internal current collector 37 a inserted into the outer peripheral surface 32 c extends through another slit 32 f formed in the porous substrate 32. As described above, the positive electrode 34 and the negative electrode 36 are accommodated in the mutually different through holes 32d, thereby reliably preventing a short circuit between the positive and negative electrodes, and providing a large number of the positive electrodes 34 and the negative electrodes 36 to significantly increase the reaction area. High output can be realized. Further, since the positive electrode internal current collector 35a and the negative electrode internal current collector 37a extend to the outer peripheral surface 32c through different slits 32e and 32f, current collection is easy. In this regard, the negative electrode external current collector 35b connected to the end portions of the plurality of negative electrode internal current collectors 37a is provided on the outer peripheral surface 32c with the positive electrode external current collector 35b connected to the end portions of the plurality of positive electrode internal current collectors 35a. It is more preferable that the body 37b is provided in a region where the positive electrode external current collector 35b does not exist on the outer peripheral surface 32c from the viewpoint of further enhancing the current collecting ability. For example, the positive electrode external current collector 35b is provided on a specific side of the outer peripheral surface 32c, and the negative electrode external current collector 37b is provided on the opposite side of the outer peripheral surface 32c from the positive electrode external current collector 35b. This is particularly preferable in that the current collector is easily arranged.

  The monolithic secondary battery is not limited to the nickel-zinc secondary battery 30 shown in FIG. 3 but can be applied to other types of zinc secondary batteries. For example, in the case of a zinc-air secondary battery, the positive electrode current collector is preferably configured to have air permeability so that air can reach the positive electrode. An example of such a monolithic zinc-air secondary battery is shown in FIG. The zinc-air secondary battery 40 having a monolith structure shown in FIG. 4 has a prismatic porous base material 42, a negative electrode 46, a negative electrode internal current collector 47a, and a negative electrode external current collector 47b shown in FIG. The porous substrate 32, the negative electrode 36, the negative electrode internal current collector 37a, and the negative electrode external current collector 37b can be configured in the same manner, but the air electrode 44 as the positive electrode, the positive electrode internal current collector 45a, and the positive electrode external current collector 45 is different from that shown in FIG. 3 and is preferably configured so that air can be supplied to the air electrode 44 from the outside. The hydroxide ion conductive ceramic separator 48 may be formed on the inner wall surface of all the through holes 42d, or may be formed only on the inner wall surface of the through hole 42d in which the air electrode 44 is accommodated as shown in FIG. May be. In any case, as shown in FIG. 4, it is preferable that the positive electrode internal current collector 45a has a breathable structure such as a hollow shape or a foam structure so that air from the outside can flow in. In this case, the positive electrode external current collector 45b connected to the positive electrode internal current collector 45a is formed with a vent 45c that communicates with a hollow structure of the positive electrode internal current collector 45a or a gas permeable structure such as a foam structure. desirable. According to such a configuration, it is possible to efficiently supply air to the air electrode 44 while ensuring a sufficient current collecting function.

  The secondary batteries 30 and 40 having a monolith structure shown in FIGS. 3 and 4 use prismatic porous base materials 32 and 42, respectively, but a cylindrical porous base material may be used. Needless to say. FIGS. 5 and 6 show examples of a monolithic nickel-zinc secondary battery 50 and a zinc-air secondary battery 60 using a cylindrical porous substrate, respectively. The nickel-zinc secondary battery 50 shown in FIG. 5 includes a positive electrode 54, a negative electrode 56, a positive electrode internal current collector 55a, a negative electrode internal current collector 57a, and a ceramic separator 58. 36, may be configured in the same manner as the positive electrode internal current collector 35a, the negative electrode internal current collector 37a, and the ceramic separator 38, but the porous substrate 52 is configured in a cylindrical shape, and accordingly, the positive electrode external current collector 55b and the negative electrode external The current collector 57 b is formed in a curved shape along the outer peripheral surface of the cylindrical porous substrate 52. The monolithic zinc-air secondary battery 60 shown in FIG. 6 includes an air electrode 64, a negative electrode 66, a positive electrode internal current collector 65a, a negative electrode internal current collector 67a, and a ceramic separator 68, as shown in FIG. The negative electrode 46, the positive electrode internal current collector 45 a, the negative electrode internal current collector 47 a, and the ceramic separator 48 can be configured in the same manner, but the porous base material 62 is configured in a cylindrical shape, and accordingly, the positive electrode external current collector 65 b and The negative electrode external current collector 67 b is formed in a curved shape along the outer peripheral surface of the cylindrical porous substrate 62.

  In any of the above-described embodiments, the hydroxide ion conductive ceramic separator is formed on the inner wall surface of the cell hole, and is provided so as to isolate the positive electrode and / or the negative electrode from the porous substrate. Or a layered member. The ceramic separator must be in contact with the alkaline electrolyte on at least one side to enable efficient movement of the required hydroxide ions between the positive electrode side and the negative electrode side, thereby realizing a charge / discharge reaction at the positive electrode and the negative electrode. Can do. As described above, when a secondary battery such as a zinc-nickel battery or a zinc-air secondary battery is configured using such a ceramic separator, a short circuit due to zinc dendrite (particularly in the case of a metal-air secondary battery) Can prevent carbon dioxide contamination. In order to maximize this effect, it is desired to reliably partition the positive electrode side compartment and the negative electrode side compartment with a hydroxide ion conductive ceramic separator. In this regard, according to the configuration of the present invention, the hydroxide ion conductive ceramic separator is formed on the inner wall surface of the cell hole of the porous substrate, so that it is between the positive electrode and the porous substrate and / or the negative electrode. And the porous substrate can be reliably separated while ensuring hydroxide ion conductivity, that is, the positive electrode side compartment and the negative electrode side compartment in the secondary battery are separated by a hydroxide ion conductive ceramic separator. It can be reliably partitioned.

  The hydroxide ion conductive ceramic separator is preferably in the form of a film or a layer that is so dense that it does not have water permeability (more desirably water permeability and air permeability). That is, the fact that the separator or inorganic solid electrolyte body does not have water permeability and air permeability means that the separator or inorganic solid electrolyte body has a high degree of denseness that does not allow water and gas to pass through. It means that it is not a porous film or other porous material having air permeability. For this reason, in the case of a zinc secondary battery, it becomes a very effective structure for preventing the short circuit between positive and negative electrodes by physically blocking the penetration of the separator by the zinc dendrite generated during charging. Further, in the case of a metal-air secondary battery, a configuration that is extremely effective in preventing the infiltration of carbon dioxide in the air and preventing the precipitation of alkali carbonate (caused by carbon dioxide) in the electrolyte. It becomes. In any case, since the ceramic separator has hydroxide ion conductivity, it enables efficient movement of the required hydroxide ions between the positive electrode side and the negative electrode side, realizing charge / discharge reactions at the positive electrode and negative electrode can do.

  The ceramic separator is preferably made of an inorganic solid electrolyte body having hydroxide ion conductivity. By using a hydroxide ion conductive inorganic solid electrolyte as a separator, the electrolyte solution between the positive and negative electrodes is isolated and hydroxide ion conductivity is ensured. 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 ceramic separator 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 is a composite of an open-pore porous material 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 material. It may be a body. 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 preferably comprises 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. 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.

  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 is preferably in the form of a film or a layer. In this case, the inorganic solid electrolyte body in the form of a film or layer is formed on or in a porous substrate. Is preferred. In particular, the thin film-like or layered form has an advantage that the resistance of the separator can be significantly reduced while ensuring the minimum necessary rigidity for preventing the penetration of zinc dendrite. 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 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.

  The positive electrode and / or negative electrode and the porous substrate are preferably impregnated with an alkaline electrolyte. The electrolytic solution may be any alkaline electrolytic solution that can be used in a secondary battery, but is preferably an aqueous alkali metal hydroxide solution. Examples of the alkali metal hydroxide include potassium hydroxide, sodium hydroxide, lithium hydroxide, ammonium hydroxide and the like, and potassium hydroxide is more preferable. In the case of a zinc secondary battery, a zinc compound such as zinc oxide or zinc hydroxide may be added to the electrolytic solution in order to suppress self-dissolution of the zinc alloy. As described above, the alkaline electrolyte may be mixed with the positive electrode and / or the negative electrode to be present in the form of a positive electrode mixture and / or a 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.

When the separator contains a layered double hydroxide (LDH), it is preferable that a compound containing Al is dissolved in the electrolytic solution. When LDH is brought into contact with an alkali metal hydroxide aqueous solution such as an aqueous potassium hydroxide solution, Al, which is a typical constituent element of LDH, may elute into the aqueous solution, leading to deterioration of the dense film. By adding the compound to be contained in the electrolytic solution, it is possible to prevent such elution of Al and deterioration of the dense film caused thereby. The Al may be dissolved in the electrolytic solution in some form, and can typically be dissolved in the electrolytic solution in the form of a metal ion, a hydroxide and / or a hydroxy complex. For example, as ^the form in which Al is _{^{dissolved, Al 3+, Al (OH)}} 2+, Al (OH) 2 +, Al (OH) 3 0, Al (OH) 4 -, Al (OH) 5 2- etc. Can be mentioned. Preferable examples of the metal compound containing Al include aluminum hydroxide, γ alumina, α alumina, boehmite, diaspore, hydrotalcite, and any combination thereof, and more preferably aluminum hydroxide and / or γ alumina. And most preferably aluminum hydroxide. The compound containing Al is preferably added so that the Al concentration in the electrolytic solution is 0.001 mol / L or more, more preferably 0.01 mol / L or more, further preferably 0.1 mol / L or more, particularly preferably. 1.0 mol / L or more, most preferably 2.0 mol / L or more, more than 3.0 mol / L, or 3.3 mol / L or more. The upper limit of the concentration of Al in the electrolytic solution is not particularly limited, and may reach the saturation solubility of the Al compound, but is, for example, 20 mol / L or less or 10 mol / L or less.

  The porous substrate, the positive electrode, the negative electrode, the positive electrode internal current collector, the negative electrode internal current collector, the hydroxide ion conductive ceramic separator, and the alkaline electrolyte are preferably housed in a container. In particular, in the secondary battery of the present invention, the columnar porous substrate includes a positive electrode, a negative electrode, a positive electrode internal current collector, a negative electrode internal current collector, a hydroxide ion conductive ceramic separator, and an alkaline electrolyte. Therefore, the porous substrate may be accommodated in the container as it is. As a result, the alkaline electrolyte can be reliably held in the secondary battery. However, when the positive electrode is an air electrode, it is needless to say that an air electrode opening is desired so that external air can be supplied to the air electrode. Further, the positive electrode external current collector and / or the negative electrode external current collector may constitute a part of the container. In any case, at least a porous substrate, a positive electrode (except for an air electrode), a positive electrode internal current collector (except for an air electrode), a negative electrode, a negative electrode internal current collector, hydroxide ion It is preferable that the conductive ceramic separator and the alkaline electrolyte be securely sealed by a container (or a composite member of the container and an external current collector). Therefore, the container preferably has a structure having liquid tightness and air tightness. The container is preferably a resin container, and the resin constituting the resin container is preferably a resin having resistance to an alkali metal hydroxide such as potassium hydroxide, more preferably a polyolefin resin, an ABS resin, or a modified polyphenylene. An ether, more preferably an ABS resin or a modified polyphenylene ether. It is preferable that a ceramic separator and / or a porous member be fixed to the container using a commercially available adhesive or by heat sealing.

Nickel-zinc secondary battery According to a preferred embodiment of the present invention, a nickel-zinc secondary battery is provided. Therefore, a basic configuration of a nickel zinc secondary battery using a hydroxide ion conductive ceramic separator together with a porous substrate will be described below. For convenience of explanation, the following description is based on a simpler unit battery rather than a form having a plurality of cell holes as in the present invention, but the basic configuration disclosed below is The same applies to the secondary battery of the present invention as long as the technical consistency is not impaired. FIG. 7 schematically shows an example of a nickel zinc secondary battery. The nickel-zinc secondary battery shown in FIG. 7 shows an initial state before charging, and corresponds to an end-of-discharge state. However, it goes without saying that the nickel-zinc secondary battery of this embodiment may be configured in a fully charged state. As shown in FIG. 7, the nickel zinc secondary battery 110 according to this embodiment includes a positive electrode 112, a positive electrode electrolyte 114, a negative electrode 116, a negative electrode electrolyte 118, and a ceramic separator 120 in a container 122. The positive electrode 112 includes nickel hydroxide and / or nickel oxyhydroxide. The positive electrode electrolyte 114 is an alkaline electrolyte containing an alkali metal hydroxide, and the positive electrode 112 is immersed therein. The negative electrode 116 includes zinc and / or zinc oxide. The negative electrode electrolyte 118 is an alkaline electrolyte containing an alkali metal hydroxide, and the negative electrode 116 is immersed therein. The container 122 accommodates the positive electrode 112, the positive electrode electrolyte 114, the negative electrode 116, and the negative electrode electrolyte 118. The positive electrode 112 and the positive electrode electrolyte 114 are not necessarily separated from each other, and may be configured as a positive electrode mixture in which the positive electrode 112 and the positive electrode electrolyte 114 are mixed. Similarly, the negative electrode 116 and the negative electrode electrolyte 118 are not necessarily separated from each other, and may be configured as a negative electrode mixture in which the negative electrode 116 and the negative electrode electrolyte 118 are mixed. If desired, a positive electrode current collector 113 is provided in contact with the positive electrode 112. Further, a negative electrode current collector 117 is provided in contact with the negative electrode 116 as desired.

The separator 120 is provided in the container 122 so as to partition a positive electrode chamber 124 that stores the positive electrode 112 and the positive electrode electrolyte 114 and a negative electrode chamber 126 that stores the negative electrode 116 and the negative electrode electrolyte 118. The separator 120 has hydroxide ion conductivity but does not have water permeability. That is, the fact that the separator 120 does not have water permeability means that the separator 120 has a high degree of denseness that does not allow water to pass through, and is not a porous film or other porous material having water permeability. Means. 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. However, it goes without saying that a porous substrate 128 may be attached to the separator 120 as shown in FIG. In any case, since the separator 120 has hydroxide ion conductivity, it enables efficient transfer of necessary hydroxide ions between the positive electrode electrolyte 114 and the negative electrode electrolyte 118, and the positive electrode chamber 124 and the negative electrode. The charge / discharge reaction in the chamber 126 can be realized. The reaction during charging in the positive electrode chamber 124 and the negative electrode chamber 126 is as shown below, and the discharge reaction is reversed.
-Positive electrode: Ni (OH) ₂ + OH ⁻ → NiOOH + H ₂ O + e ⁻
-Negative electrode: ZnO + H ₂ O + 2e ⁻ → Zn + 2OH ⁻

However, the negative electrode reaction is composed of the following two reactions.
-ZnO dissolution reaction: ZnO + H ₂ O + 2OH ⁻ → Zn (OH) ₄ ²⁻
-Zn precipitation reaction: Zn (OH) ₄ ^2- + 2e ⁻ → Zn + 4OH ⁻

  The nickel zinc secondary battery 110 has a positive electrode-side surplus space 125 having a volume that allows an increase or decrease in the amount of water accompanying the positive electrode reaction during charge / discharge in the positive electrode chamber 124, and the negative electrode reaction during charge / discharge in the negative electrode chamber 126. It is preferable to have a negative electrode-side surplus space 127 having a volume that allows a decrease in the amount of water accompanying the increase. This effectively prevents inconvenience (for example, liquid leakage, deformation of the container due to a change in the container internal pressure, etc.) associated with increase or decrease in the amount of water in the positive electrode chamber 124 and the negative electrode chamber 126, and the reliability of the nickel zinc secondary battery. Can be further improved. That is, as can be seen from the above reaction formula, during charging, water increases in the positive electrode chamber 124 while water decreases in the negative electrode chamber 126. On the other hand, during discharge, water decreases in the positive electrode chamber 124 while water increases in the negative electrode chamber 126. In this respect, since most conventional separators have water permeability, water can freely pass through the separators. However, since the separator 120 used in this embodiment has a highly dense structure that does not have water permeability, water cannot freely pass through the separator 120, and the charge chamber is charged and discharged, and / or in the negative electrode chamber 124 and / or the negative electrode chamber. In 126, the amount of the electrolyte may increase unilaterally and cause problems such as liquid leakage. In view of this, the positive electrode chamber 124 has a positive electrode side excess space 125 having a volume that allows an increase or decrease in the amount of water associated with the positive electrode reaction during charging and discharging, thereby increasing the positive electrode electrolyte 114 during charging as shown in FIG. It can be made to function as a buffer that can cope with this. That is, as shown in FIG. 8, the positive electrode side excess space 125 functions as a buffer even after full charge, so that the increased amount of the positive electrode electrolyte solution 114 is reliably held in the positive electrode chamber 124 without overflowing. Can do. Similarly, the negative electrode chamber 126 has a negative electrode-side surplus space 127 having a volume that allows a decrease in the amount of water accompanying a negative electrode reaction during charge / discharge, thereby functioning as a buffer that can cope with an increase in the negative electrode electrolyte 118 during discharge. Can be made.

The increase / decrease amount of moisture in the positive electrode chamber 124 and the negative electrode chamber 126 can be calculated based on the above-described reaction formula. As can be seen from the reaction formula described above, the amount of H ₂ O produced at the positive electrode 112 during charging corresponds to twice the amount of H ₂ O consumed at the negative electrode 116. Therefore, the volume of the positive electrode side surplus space 125 may be larger than that of the negative electrode side surplus space 127. In any case, the volume of the positive-side surplus space 125 can be generated from the positive electrode 112 not only in the amount of water increase expected in the positive electrode chamber 124 but also in a gas such as air pre-existing in the positive electrode chamber 124 or overcharge. It is preferable that the volume has a slight or some margin so that oxygen gas can be accommodated at an appropriate internal pressure. In this regard, it can be said that it is sufficient that the negative-side surplus space 127 has the same volume as the positive-side surplus space 125 as shown in FIG. It is desirable to provide a surplus space that exceeds the amount of water reduction. In any case, the negative electrode-side surplus space 127 may be smaller than the positive electrode-side surplus space 125 because only about half of the amount in the positive electrode chamber 124 is increased or decreased.

  When the nickel zinc secondary battery 110 is constructed in a discharged state, the positive-side surplus space 125 has a volume that exceeds the amount of water expected to increase with the positive-electrode reaction during charging, and the positive-side surplus The space 125 is not filled with the positive electrode electrolyte 114 in advance, and the negative electrode side surplus space 127 has a volume exceeding the amount of moisture expected to decrease with the negative electrode reaction during charging, and the negative electrode side surplus The space 127 is preferably prefilled with an amount of the negative electrode electrolyte 118 that is expected to decrease. On the other hand, when the nickel-zinc secondary battery 110 is constructed in a fully charged state, the positive electrode side surplus space 125 has a volume exceeding the amount of water expected to decrease with the positive electrode reaction during discharge, The side excess space 125 is pre-filled with an amount of the positive electrode electrolyte 114 that is expected to decrease, and the negative side excess space 127 has a moisture amount that is expected to increase with the negative electrode reaction during discharge. It is preferable that the negative electrode side excess space 127 is not filled with the negative electrode electrolyte 118 in advance.

  The positive electrode side surplus space 125 is preferably not filled with the positive electrode 112 and / or the negative electrode side surplus space 127 is preferably not filled with the negative electrode 116, and the positive electrode side surplus space 125 and the negative electrode side surplus space 127 are filled with the positive electrode 112. More preferably, the negative electrode 116 and the negative electrode 116 are not filled. In these surplus spaces, electrolyte can be depleted due to a decrease in the amount of water during charging and discharging. That is, even if these surplus spaces are filled with the positive electrode 112 and the negative electrode 116, they cannot be fully involved in the charge / discharge reaction, which is inefficient. Accordingly, the positive electrode 112 and the negative electrode 116 can be more efficiently and stably involved in the battery reaction without waste by not filling the positive electrode side excessive space 125 and the negative electrode side excessive space 127 with the positive electrode 112 and the negative electrode 116, respectively.

  The separator 120 is a member having hydroxide ion conductivity but not water permeability, and typically has a plate shape, a film shape, or a layer shape. The separator 120 is provided in the container 122 and partitions the positive electrode chamber 124 that stores the positive electrode 112 and the positive electrode electrolyte 114 and the negative electrode chamber 126 that stores the negative electrode 116 and the negative electrode electrolyte 118. Further, as described above, 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 positive electrode 112 and the separator 120 and / or between the negative electrode 116 and the separator 120, Even when the electrolyte is decreased, the electrolyte may be held in the reaction portion of the positive electrode and / or the negative electrode. Preferable examples of the water absorbent resin or the liquid retaining resin include polyolefin resins.

  The positive electrode 112 includes nickel hydroxide and / or nickel oxyhydroxide. For example, when a nickel zinc secondary battery is configured in a discharged state as shown in FIG. 7, nickel hydroxide may be used as the positive electrode 112, and when configured in a fully charged state as shown in FIG. May use nickel oxyhydroxide as the positive electrode 112. Nickel hydroxide and nickel oxyhydroxide (hereinafter referred to as nickel hydroxide or the like) are positive electrode active materials generally used in nickel zinc secondary batteries and are typically in the form of particles. In nickel hydroxide or the like, different elements other than nickel may be dissolved in the crystal lattice, thereby improving the charging efficiency at high temperatures. Examples of such different elements include zinc and cobalt. In addition, nickel hydroxide or the like may be mixed with a cobalt-based component, and examples of such a cobalt-based component include granular materials of metallic cobalt and cobalt oxide (for example, cobalt monoxide). . Furthermore, the surface of particles such as nickel hydroxide (which may contain different elements in solid solution) may be coated with a cobalt compound. Examples of such cobalt compounds include cobalt monoxide, divalent α-type. Examples include cobalt hydroxide, divalent β-type cobalt hydroxide, compounds of higher-order cobalt exceeding 2 valences, and any combination thereof.

  The positive electrode 112 may further contain an additional element in addition to the nickel hydroxide compound and the different element that can be dissolved therein. Examples of such additional elements include scandium (Sc), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), Gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), elpium (Er), thulium (Tm), lutetium (Lu), hafnium (Hf), tantalum (Ta), tungsten (W), Examples include rhenium (Re), osmium (Os), iridium (Ir), platinum (Pt), gold (Au) and mercury (Hg), and any combination thereof. The inclusion form of the additional element is not particularly limited, and may be contained in the form of a simple metal or a metal compound (for example, oxide, hydroxide, halide, and carbonate). When adding a single metal or a metal compound containing an additional element, the addition amount is preferably 0.5 to 20 parts by weight, more preferably 2 to 5 parts by weight, with respect to 100 parts by weight of the nickel hydroxide compound. It is.

  The positive electrode 112 may be configured as a positive electrode mixture by further containing an electrolytic solution or the like. The positive electrode mixture can include nickel hydroxide compound particles, an electrolytic solution, and optionally a conductive material such as carbon particles, a binder, and the like.

  A positive electrode current collector 113 is preferably provided in contact with the positive electrode 112. As shown in FIG. 7, the positive electrode current collector 113 may penetrate the container 122 and extend to the outside thereof to constitute the positive electrode terminal itself, or the positive electrode terminal provided separately in the container 122. Or it is good also as a structure connected outside. Preferable examples of the positive electrode current collector 113 include a nickel porous substrate such as a foamed nickel plate. In this case, for example, a positive electrode plate made of the positive electrode 112 / the positive electrode current collector 113 is preferably prepared by uniformly applying and drying a paste containing an electrode active material such as nickel hydroxide on a nickel porous substrate. Can do. At that time, it is also preferable to press the dried positive electrode plate (that is, positive electrode 112 / positive electrode current collector 113) to prevent the electrode active material from falling off and to improve the electrode density.

  The negative electrode 116 includes zinc and / or zinc oxide. Zinc may be contained in any form of zinc metal, zinc compound and zinc alloy as long as it has an electrochemical activity suitable for the negative electrode. Preferable examples of the negative electrode material include zinc oxide, zinc metal, calcium zincate and the like, and a mixture of zinc metal and zinc oxide is more preferable. The negative electrode 116 may be formed in a gel form, or may be mixed with an electrolytic solution to form a negative electrode mixture. For example, a gelled negative electrode can be easily obtained by adding an electrolytic solution and a thickener to the negative electrode active material. Examples of the thickener include polyvinyl alcohol, polyacrylate, CMC, alginic acid and the like. Polyacrylic acid is preferable because it has excellent chemical resistance to strong alkali.

  As the zinc alloy, a zinc alloy containing no mercury and lead, which is known as a non-free zinc alloy, can be used. For example, a zinc alloy containing 0.01 to 0.06 mass% indium, 0.005 to 0.02 mass% bismuth, and 0.0035 to 0.015 mass% aluminum has an effect of suppressing hydrogen gas generation. Therefore, it is preferable. In particular, indium and bismuth are advantageous in improving the discharge performance. The use of the zinc alloy for the negative electrode can improve the safety by suppressing the generation of hydrogen gas by slowing the self-dissolution rate in the alkaline electrolyte.

  The shape of the negative electrode material is not particularly limited, but it is preferably a powder form, which increases the surface area and can cope with a large current discharge. In the case of a zinc alloy, the preferable average particle size of the negative electrode material is in the range of 90 to 210 μm. Easy to mix evenly and easy to handle during battery assembly.

  A negative electrode current collector 117 is preferably provided in contact with the negative electrode 116. As shown in FIG. 7, the negative electrode current collector 117 may penetrate the container 122 and extend to the outside thereof to constitute the negative electrode terminal itself, or the negative electrode terminal provided separately may be provided in the container 122. Or it is good also as a structure connected outside. A preferred example of the negative electrode current collector 117 is copper punching metal. In this case, for example, a mixture containing zinc oxide powder and / or zinc powder and, optionally, a binder (for example, polytetrafluoroethylene particles) is applied on copper punching metal, and the negative electrode 116 / negative electrode current collector 117 is applied. A negative electrode plate can be preferably produced. At that time, it is also preferable to press the dried negative electrode plate (that is, negative electrode 116 / negative electrode current collector 117) to prevent the electrode active material from falling off and to improve the electrode density.

Zinc Air Secondary Battery According to another preferred embodiment of the present invention, a zinc air secondary battery is provided. According to a preferred embodiment of the present invention, a zinc-air secondary battery is provided. Therefore, a basic configuration of a zinc-air secondary battery using a hydroxide ion conductive ceramic separator together with a porous substrate will be described below. For convenience of explanation, the following description is based on a simpler unit battery rather than a form having a plurality of cell holes as in the present invention, but the basic configuration disclosed below is The same applies to the secondary battery of the present invention as long as the technical consistency is not impaired. 9A and 9B schematically show an example of a zinc-air secondary battery. As shown in FIGS. 9A and 9B, the zinc-air secondary battery 130 according to this embodiment includes an air electrode 132, a negative electrode 134, an alkaline electrolyte 136, a ceramic separator 140, a container 146, and, if desired, a third electrode 138. Become. The air electrode 132 functions as a positive electrode. The negative electrode 134 includes zinc, a zinc alloy, and / or a zinc compound. The electrolytic solution 136 is an aqueous electrolytic solution in which the negative electrode 134 is immersed. The container 146 has an opening 146 a and accommodates the negative electrode 134, the electrolytic solution 136, and the third electrode 138. The separator 140 closes the opening 146a so as to be in contact with the electrolyte solution 136 to form a container 146 and a negative electrode side sealed space, thereby isolating the air electrode 132 and the electrolyte solution 136 so that hydroxide ions can be conducted. If desired, a positive electrode current collector 142 may be provided in contact with the air electrode 132. Further, if desired, the negative electrode current collector 144 may be provided in contact with the negative electrode 134, and in that case, the negative electrode current collector 144 can also be accommodated in the container 146.

  As described above, the separator 140 is preferably a member having hydroxide ion conductivity but not water permeability and air permeability, and typically has a plate shape, a film shape, or a layer shape. The separator 140 closes the opening 146a so as to be in contact with the electrolytic solution 136 to form the container 146 and the negative electrode side sealed space, thereby isolating the air electrode 132 and the electrolytic solution 136 so that hydroxide ions can be conducted. A porous substrate 148 may be provided on one side or both sides of the separator 140, preferably on one side (electrolyte side). Further, a water retention member made of a water-absorbing resin such as a nonwoven fabric or a liquid retention resin is disposed between the negative electrode 134 and the separator 140, so that even if the electrolyte solution 136 decreases, the electrolyte solution 136 is replaced with the negative electrode 134 and the separator 140. It is good also as a structure hold | maintained so that contact is always possible. This water retaining member may also serve as the water retaining member for the third electrode 138 described above, or a water retaining member for the separator 140 may be used separately. 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 air electrode 132 may be a known air electrode used in a metal-air battery such as a zinc-air battery, and is not particularly limited. The air electrode 132 typically comprises 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 132 includes such an electron conductive material / air electrode catalyst, and, optionally, a hydroxide ion conductive material. It may be a thing.

  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 132 is not specifically limited, 5-70 volume% is preferable with respect to the total amount of the air electrode 132, 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 140 (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 132. 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 132 is not specifically limited, 10-80 volume% is preferable with respect to the total amount of the air electrode 132, More preferably, it is 15-80 volume%, More preferably, it is 20-80. % By volume.

The air electrode 132 may further include a hydroxide ion conductive material as an optional component. In particular, when the separator 140 is made of a hydroxide ion conductive inorganic solid electrolyte, which is a dense ceramic, on the separator 140 (with an intermediate layer having hydroxide ion conductivity if desired), conventionally. By forming the air electrode 132 containing not only the air electrode catalyst and the electron conductive material used but also the hydroxide ion conductive material, the desired characteristics by the separator 140 made of dense ceramics can be secured. 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 132, 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 140 (or the intermediate layer, if applicable) and the air electrode 132 but also in the air electrode 132, 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 this coating film, the ion conductive material is not dense and has open pores, and the interface from the outer surface of the air electrode 132 to the separator 140 (or 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 132 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 132. 10 to 80% by volume.

  The formation of the air electrode 132 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 the current collector to form the air electrode 132, and the air electrode 132 / the air electrode 132 side of the laminated sheet of the current collector is pressure-bonded to the separator 140 (or an intermediate layer if applicable). May be. Alternatively, an air electrode catalyst, an electron conductive material, and optionally 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 132. It may be formed. Therefore, the air electrode 132 may contain a binder. The binder may be a thermoplastic resin or a thermosetting resin and is not particularly limited.

  The air electrode 132 is preferably in the form of a layer 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.

  A positive electrode current collector 142 having air permeability is preferably provided on the side of the air electrode 132 opposite to the separator 140. In this case, the positive electrode current collector 142 preferably has air permeability so that air is supplied to the air electrode 132. Preferable examples of the positive electrode current collector 142 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.

  An intermediate layer may be provided between the separator 140 and the air electrode 132. The intermediate layer is not particularly limited as long as it improves the adhesion between the separator 140 and the air electrode 132 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, at least one of the polymer material and the ceramic material included in the intermediate layer may have hydroxide ion conductivity. That's fine. 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, it is easy to improve the adhesion between the separator 140 and the air electrode 132, and the battery resistance (particularly, the interface resistance between the air electrode and the separator) is more effectively reduced in the zinc-air secondary battery. Can do.

  The negative electrode 134 includes zinc, a zinc alloy, and / or a zinc compound that functions as a negative electrode active material. The negative electrode 134 may have any shape or form such as a particle shape, a plate shape, or a gel shape, but it is preferable that the negative electrode 134 be a particle shape or a gel shape from the viewpoint 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, 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 144 is preferably provided in contact with the negative electrode 134. As shown in FIGS. 9A and 9B, the negative electrode current collector 144 may extend through the container 146 to the outside thereof to form the negative electrode terminal itself, or the negative electrode terminal provided separately may It is good also as a structure connected in 146 inside or outside. Preferable examples of the negative electrode current collector include a metal plate or metal mesh such as stainless steel, copper (for example, copper punching metal), nickel, carbon paper, and an oxide conductor. For example, a negative electrode plate composed of a negative electrode 134 / a negative electrode current collector 144 by applying a mixture containing zinc oxide powder and / or zinc powder and optionally a binder (for example, polytetrafluoroethylene particles) on copper punching metal. Can be preferably produced. At that time, it is also preferable to press the dried negative electrode plate (that is, the negative electrode 134 / negative electrode current collector 144) to prevent the electrode active material from falling off and to improve the electrode density.

If desired, the third electrode 138 may be provided so as to contact the electrolyte solution 136 but not to contact the negative electrode 134. In this case, the third electrode 138 is connected to the air electrode 132 via an external circuit. With such a configuration, hydrogen gas that can be generated by a side reaction from the negative electrode 134 is brought into contact with the third electrode 138 and the following reaction is performed:
Third electrode: H ₂ + 2OH ⁻ → 2H ₂ O + 2e ⁻
Positive electrode discharge: O ₂ + 2H ₂ O + 4e ⁻ → 4OH ⁻
Can be returned to the water. In other words, hydrogen gas generated at the negative electrode 134 is absorbed by the third electrode 138 and self-discharge occurs. 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 138 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 132 through an external circuit. However, it is desirable that the oxygen overvoltage is larger than that of the air electrode 132. It is also desirable that the third electrode 138 does not participate in normal charge / discharge reactions. The third electrode 138 preferably comprises platinum and / or a carbon material, and more preferably comprises 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 the 3rd electrode 138 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. The third electrode 138 (preferably the third electrode having a large specific surface area) is more preferably applied and / or disposed on the current collector. The current collector for the third electrode 138 may have any shape, but preferred examples include wire (eg, wire), punching metal, mesh, foam metal, and any combination thereof. The material of the current collector for the third electrode 138 may be the same material as that of the third electrode 138, or may be a metal (for example, nickel), an alloy, or other conductive material.

  The third electrode 138 is in contact with the electrolytic solution 136, but it is desirable that the third electrode 138 be disposed at a place not directly related to the normal charge / discharge reaction. In this case, even when the electrolyte solution is reduced by disposing a water-holding member made of a water-absorbing resin such as a nonwoven fabric or a liquid-retaining resin so as to be in contact with the third electrode 138 in the negative electrode side sealed space, the electrolytic solution 136 is reduced. Is preferably configured to be held in contact with the third electrode 138 at all times. 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 138 does not necessarily need to be impregnated with a large amount of electrolytic solution 136, and can exhibit a desired function even when wet with a small amount or a small amount of electrolytic solution 136. As long as the water retaining member has.

LDH separator with porous substrate In the secondary battery of the present invention, a hydroxide ion conductive ceramic separator is formed on the inner wall surface of the cell hole of the porous substrate. That is, it can be said that the secondary battery of the present invention includes a ceramic separator with a porous substrate. Therefore, for convenience of explanation, the following description is based on a ceramic separator using a simpler plate-like porous substrate, not a porous substrate having a plurality of cell holes as in the present invention. However, the basic configuration disclosed below applies to the secondary battery of the present invention as long as the technical consistency is not impaired.

  As described above, the separator with a porous substrate preferably used for the secondary battery of the present invention is a separator made of an inorganic solid electrolyte body having hydroxide ion conductivity and a porous provided on at least one surface of the separator. And a substrate. 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 comprises 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. 10, the separator layer 120 is preferably formed on the porous substrate 128 as an LDH dense film. In this case, needless to say, LDH may be formed on the surface of the porous base material 128 and in the pores in the vicinity thereof as shown in FIG. 10 due to the nature of the porous base material 128. Alternatively, as shown in FIG. 11, 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. 11 has a configuration in which the membrane equivalent portion in the separator layer 120 of the embodiment shown in FIG. 10 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. 10, the separator layer 120 is in the form of an LDH dense film, which is typically from LDH. Become. When the separator layer 120 ′ is formed in the porous substrate 128 as shown in FIG. 11, the surface of the porous substrate 128 (typically the surface of the porous substrate 128 and its vicinity) 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. 11 can be obtained by removing a portion corresponding to the film in the separator layer 120 shown in FIG. 10 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). )[image]
→ Create a black and white binary image by the procedure of [Color correction] → [2 gradation]. 4) The porosity (%) is 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. 10, 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. 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. 12, but the above-mentioned substantially vertical or oblique orientation has an 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 LDH separator with a porous base material described above is (a) a porous base material is prepared, and (b) a starting material capable of giving a starting point for crystal growth of LDH is uniformly attached to the porous base material, if desired. (C) The porous substrate can be preferably manufactured by subjecting the porous substrate to hydrothermal treatment to form an LDH film.

(A) 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, and particularly preferred are alumina, zirconia (eg, yttria stabilized zirconia (YSZ)), and combinations thereof. When these porous ceramics are used, the density of the LDH film 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.

  As described above, the porous substrate is more preferably composed of a ceramic material. The porous substrate made of a ceramic material may be a commercially available product or may be prepared according to a known technique, and is not particularly limited. For example, ceramic powder (for example, zirconia powder, boehmite powder, titania powder, etc.), methylcellulose, and ion-exchanged water are kneaded at a desired blending ratio, the obtained kneaded product is subjected to extrusion molding, and the resulting molded body is obtained. After drying at 70 to 200 ° C. for 10 to 40 hours, a porous substrate made of a ceramic material can be produced by firing at 900 to 1300 ° C. for 1 to 5 hours. The blending ratio of methylcellulose is preferably 1 to 20 parts by weight with respect to 100 parts by weight of the ceramic powder. Further, the blending ratio of the ion exchange water is preferably 10 to 100 parts by weight with respect to 100 parts by weight of the ceramic powder.

(B) Attachment of starting material If desired, a starting material that can provide a starting point for crystal growth of LDH may be uniformly attached to the porous substrate. After the starting material is uniformly attached to the surface of the porous substrate in this way, the subsequent step (c) is performed, so that a highly densified LDH film can be uniformly formed on the surface of the porous substrate. It can be formed uniformly. Preferable examples of such an origin include a chemical species that provides an anion that can enter between the layers of LDH, a chemical species that provides a cation that can be a constituent element of LDH, or LDH.

(I) Chemical species that provide anions The starting point of crystal growth of LDH can be a chemical species that provides anions that can enter between layers of LDH. Examples of such anions include CO ₃ ²⁻ , OH ⁻ , SO ₃ ⁻ , SO ₃ ²⁻ , SO ₄ ²⁻ , NO ₃ ⁻ , Cl ⁻ , Br ⁻ , and any combination thereof. It is done. Therefore, the starting material that can provide such a starting point may be uniformly attached to the surface of the porous substrate by an appropriate method according to the type of the starting material. By applying a chemical species that gives an anion to the surface, metal cations such as Mg ²⁺ and Al ³⁺ can be adsorbed on the surface of the porous substrate to generate LDH nuclei. Therefore, by performing the subsequent step (c), a highly densified LDH film can be uniformly formed on the surface of the porous substrate without unevenness.

According to a preferred embodiment of the present invention, the starting material can be attached by attaching a polymer to the surface of the porous substrate and then introducing a chemical species that gives an anion to the polymer. In this embodiment, the anion is preferably SO ₃ ⁻ , SO ₃ ²⁻ and / or SO ₄ ²⁻ , and introduction of a chemical species giving such an anion into the polymer is performed by sulfonation treatment. Is preferred. Polymers that can be used are anionizable (especially sulfonated) polymers, examples of such polymers include polystyrene, polyethersulfone, polypropylene, epoxy resins, polyphenylene sulfide, and any combination thereof. . In particular, the aromatic polymer is preferable in that it is easily anionized (particularly sulfonated). Examples of such aromatic polymer include polystyrene, polyethersulfone, epoxy resin, polyphenylene sulfide, and any of them. Combinations are mentioned. The most preferred polymer is polystyrene. The adhesion of the polymer to the porous substrate is performed by using a solution in which the polymer is dissolved (hereinafter referred to as a polymer solution) as the surface of the porous substrate (preferably, the outermost surface of the plate-like outline of the porous substrate). ) Is preferably applied by coating. The polymer solution can be easily prepared, for example, by dissolving a polymer solid (for example, a polystyrene substrate) in an organic solvent (for example, a xylene solution). It is preferable to prevent the polymer solution from penetrating into the porous substrate because it is easy to achieve uniform coating. In this respect, the polymer solution is preferably attached or applied by spin coating because it can be applied uniformly. The spin coating conditions are not particularly limited. For example, the spin coating may be performed at a rotational speed of 1000 to 10000 rpm for about 60 to 300 seconds including dripping and drying. On the other hand, the sulfonation treatment may be performed by immersing the porous substrate to which the polymer is attached in a sulfonateable acid such as sulfuric acid (for example, concentrated sulfuric acid), fuming sulfuric acid, chlorosulfonic acid, and sulfuric anhydride. Alternatively, the technology may be used. The immersion in the sulfonateable acid may be performed at room temperature or high temperature (for example, 50 to 150 ° C.), and the immersion time is not particularly limited, but is, for example, 1 to 14 days.

According to another preferred embodiment of the present invention, the starting material can be attached by treating the surface of the porous substrate with a surfactant containing a chemical species that gives an anion as a hydrophilic group. In this case, the anion is preferably SO ₃ ⁻ , SO ₃ ²⁻ and / or SO ₄ ²⁻ . A typical example of such a surfactant is an anionic surfactant. Preferred examples of the anionic surfactant include a sulfonic acid type anionic surfactant, a sulfate type anionic surfactant, and any combination thereof. Examples of the sulfonic acid type anionic surfactant include naphthalene sulfonic acid Na formalin condensate, polyoxyethylene sulfosuccinic acid alkyl 2Na, polystyrene sulfonic acid Na, dioctyl sulfosuccinic acid Na, polyoxyethylene lauryl ether sulfate triethanolamine. It is done. Examples of the sulfate ester type anionic surfactant include polyoxyethylene lauryl ether sulfate Na. The treatment of the porous substrate with the surfactant is not particularly limited as long as it is a technique capable of attaching the surfactant to the surface of the porous substrate, and a solution containing the surfactant is applied to the porous substrate. What is necessary is just to apply | coat or immerse a porous base material in the solution containing surfactant. The porous substrate may be immersed in the solution containing the surfactant while stirring the solution at room temperature or high temperature (for example, 40 to 80 ° C.), and the immersion time is not particularly limited, but for example, 1 to 7 days. is there.

(Ii) Chemical species that provide cations The starting point of LDH crystal growth can be a chemical species that provides cations that can be a component of the layered double hydroxide. A preferred example of such a cation is Al ³⁺ . In this case, the starting material is preferably at least one aluminum compound selected from the group consisting of aluminum oxides, hydroxides, oxyhydroxides, and hydroxy complexes. Therefore, the starting material that can provide such a starting point may be uniformly attached to the surface of the porous member by an appropriate method according to the type of the starting material. By imparting a chemical species that gives a cation to the surface, an anion that can enter between the layers of LDH can be adsorbed on the surface of the porous substrate to generate LDH nuclei. Therefore, by performing the subsequent step (c), a highly densified LDH film can be uniformly formed on the surface of the porous substrate without unevenness.

According to a preferred aspect of the present invention, the starting material can be attached by applying a sol containing an aluminum compound to the porous member. In this case, examples of preferred aluminum compounds include boehmite (AlOOH), aluminum hydroxide (Al (OH) ₃ ), and amorphous alumina, with boehmite being most preferred. The application of the sol containing the aluminum compound is preferably performed by spin coating because it can be applied uniformly. The spin coating conditions are not particularly limited. For example, the spin coating may be performed at a rotational speed of 1000 to 10000 rpm for about 60 to 300 seconds including dripping and drying.

According to another preferred embodiment of the present invention, the starting material is adhered by subjecting the porous substrate to hydrothermal treatment in an aqueous solution containing at least aluminum to form an aluminum compound on the surface of the porous substrate. be able to. The aluminum compound formed on the surface of the porous substrate is preferably Al (OH) ₃ . In particular, LDH films on porous substrates (especially ceramic porous substrates) tend to produce crystalline and / or amorphous Al (OH) _{3 in the} initial stage of growth. Can grow. Therefore, after the Al (OH) ₃ is uniformly attached to the surface of the porous substrate by hydrothermal treatment in advance, the step (c) that also involves hydrothermal treatment is performed, The LDH film can be uniformly formed without unevenness. In this embodiment, the step (b) and the subsequent step (c) may be performed continuously in the same sealed container, or the step (b) and the subsequent step (c) are performed separately in this order. May be.

When the step (b) and the step (c) are continuously performed in the same sealed container, the raw material aqueous solution (that is, the aqueous solution containing the constituent elements of LDH) used in the step (c) described later is used as it is in the step (b). Can be used. Even in this case, the hydrothermal treatment in the step (b) is compared with 50 to 70 ° C. in an acidic or neutral pH range (preferably pH 5.5 to 7.0) in an airtight container (preferably an autoclave). By performing in a low temperature region, not LDH but Al
(OH) ₃ nucleation can be promoted. In addition, after the nucleation of Al (OH) ₃ , the pH of the raw material aqueous solution rises due to the hydrolysis of urea by holding or raising the temperature at the nucleation temperature, and therefore a pH range suitable for LDH growth. It is possible to smoothly shift to step (c) at (preferably more than pH 7.0).

On the other hand, when the step (b) and the step (c) are separately performed in this order, it is preferable to use different raw material aqueous solutions in the step (b) and the step (c). For example, in step (b), it is preferable to nucleate Al (OH) ₃ using a raw material aqueous solution mainly containing an Al source (preferably not containing other metal elements). In this case, the hydrothermal treatment in the step (b) may be performed at 50 to 120 ° C. in a closed container (preferably an autoclave) different from the step (c). Preferable examples of the raw material aqueous solution mainly containing an Al source include an aqueous solution containing aluminum nitrate and urea and not containing a magnesium compound (for example, magnesium nitrate). By using a raw material aqueous solution not containing Mg, precipitation of LDH can be avoided and nucleation of Al (OH) ₃ can be promoted.

According to still another preferred embodiment of the present invention, the starting material is adhered by depositing aluminum on the surface of the porous substrate and then converting the aluminum into an aluminum compound by hydrothermal treatment in an aqueous solution. Can do. This aluminum compound is preferably Al
(OH) ₃ . In particular, by converting to Al (OH) ₃ , the growth of LDH can be promoted using this as a nucleus. Therefore, after the Al (OH) ₃ is uniformly formed on the surface of the porous base material by hydrothermal treatment, the same process (c) accompanied by hydrothermal treatment is carried out. A densified LDH film can be uniformly formed without unevenness. Aluminum may be deposited by physical vapor deposition or chemical vapor deposition, but physical vapor deposition such as vacuum vapor deposition is preferred. Moreover, the aqueous solution used for the hydrothermal treatment for aluminum conversion should just be a composition which can react with Al already provided by vapor deposition and can produce | generate Al (OH) _3, and is not specifically limited.

(Iii) LDH as a starting point
The starting point for crystal growth can be LDH. In this case, the growth of LDH can be promoted starting from the nucleus of LDH. Therefore, after the LDH nuclei are uniformly attached to the surface of the porous base material, the subsequent step (c) is performed to unevenly disperse the highly densified LDH film on the surface of the porous base material. And can be formed uniformly.

  According to a preferred aspect of the present invention, the starting material can be attached by applying a sol containing LDH to the surface of the porous member. The sol containing LDH may be prepared by dispersing LDH in a solvent such as water, and is not particularly limited. In this case, the application is preferably performed by spin coating. Spin coating is preferred because it can be applied very uniformly. The spin coating conditions are not particularly limited. For example, the spin coating may be performed at a rotational speed of 1000 to 10000 rpm for about 60 to 300 seconds including dripping and drying.

  According to another preferred embodiment of the present invention, the deposition of the starting material is performed by depositing aluminum (deposited) in an aqueous solution containing a constituent element of LDH other than aluminum after depositing aluminum on the surface of the porous substrate. It can be performed by converting to LDH by hydrothermal treatment. Aluminum may be deposited by physical vapor deposition or chemical vapor deposition, but physical vapor deposition such as vacuum vapor deposition is preferred. Moreover, the raw material aqueous solution used for the hydrothermal treatment for the conversion of aluminum may be performed using an aqueous solution containing a component other than Al already provided by vapor deposition. A preferable example of such a raw material aqueous solution is a raw material aqueous solution mainly containing a Mg source, and more preferably, an aqueous solution containing magnesium nitrate and urea and not containing an aluminum compound (aluminum nitrate). By including the Mg source, the nuclei of LDH can be formed together with Al already provided by vapor deposition.

(C) Hydrothermal treatment A hydrothermal treatment is performed on a porous substrate (a starting material can be attached if desired) in a raw material aqueous solution containing a constituent element of LDH to form an LDH film on the surface of the porous substrate. A preferable raw material aqueous solution contains magnesium ions (Mg ²⁺ ) and aluminum ions (Al ³⁺ ) at a predetermined total concentration, and contains urea. Due to the presence of urea, ammonia is generated in the solution by utilizing hydrolysis of urea, so that the pH value rises (for example, more than pH 7.0, preferably more than 7.0 and less than 8.5) and coexists. LDH can be obtained when metal ions form hydroxides. 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 balanced manner, and an LDH film 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, so that 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.

  The porous substrate may be 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.

In the raw material aqueous solution, the porous substrate is subjected to hydrothermal treatment to form an LDH film on the surface of the porous substrate. This hydrothermal treatment is preferably carried out in a sealed container (preferably an autoclave) at 60 to 150 ° C., more preferably 65 to 120 ° C., further preferably 65 to 100 ° C., 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 film.

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

  The LDH film produced as described above is one in which LDH plate-like particles are highly densified and oriented in a substantially vertical direction that is advantageous for conduction. That is, the LDH film typically does not have water permeability (desirably water permeability and air permeability) due to high density. In addition, the LDH constituting the LDH film is composed of an aggregate of a plurality of plate-like particles, and the plurality of plate-like particles cross their surfaces substantially perpendicularly or obliquely with the surface of the porous substrate. Typically oriented in the direction. Accordingly, when an LDH film having sufficient gas tightness and a dense LDH film is used for a battery such as a zinc-air battery, an improvement in power generation performance can be expected, and a secondary battery for a zinc-air battery using an electrolyte that has not been conventionally applicable It is expected to be applied to new separators such as zinc dendrite progress barriers and carbon dioxide intrusion separators, which have become major barriers to chemical conversion. Similarly, it is expected to be applied to a nickel-zinc battery in which the progress of zinc dendrite is a major barrier to practical use.

  By the way, the LDH film obtained by the above production method can be formed on both surfaces of the porous substrate. For this reason, in order to make the LDH film suitable for use as a separator, the LDH film on one side of the porous substrate is mechanically scraped after film formation, or the LDH film is formed on one side during film formation. It is desirable to take measures that prevent film formation.

  The present invention is more specifically described by the following examples. In the following examples, the example shown below is not an example of manufacturing a porous substrate and a battery having a structure according to the present invention, but an LDH dense film on the porous substrate can actually be formed, and it can be used as a separator. It is a reference example which shows that a battery can be produced using as.

Example 1 (Reference): Production and Evaluation of LDH Separator with Porous Substrate (1) Production of Porous Substrate Boehmite (manufactured by Sasol, DISPAL 18N4-80), methylcellulose, and ion-exchanged water (boehmite): After weighing so that the mass ratio of (methylcellulose) :( ion-exchanged water) was 10: 1: 5, the mixture was 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. FIG. 13 shows an SEM image of the porous substrate surface.

  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 membrane sample Using an X-ray diffractometer (Rigaku Corporation, RINT TTR III), the voltage was 50 kV, the current value was 300 mA, and the measurement range was 10 to 70 °. When the crystal phase of the sample was measured, the XRD profile shown in FIG. 14 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. 14, a peak (a peak marked with a circle in the figure) attributed 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. 15 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. 16 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. 17A, 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. 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. 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. 17B, 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. 18A and 18B, 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): Preparation and Evaluation of Nickel Zinc Secondary Battery (1) Preparation of Separator with Porous Substrate Hydrotalcite membrane on alumina substrate as a separator with porous substrate by the same procedure as in Example 1 (Size: 5 cm × 8 cm) was prepared.

(2) Preparation of positive electrode plate Nickel hydroxide particles to which zinc and cobalt were added so as to form a solid solution were prepared. The nickel hydroxide particles were coated with cobalt hydroxide to obtain a positive electrode active material. The obtained positive electrode active material was mixed with a 2% aqueous solution of carboxymethyl cellulose to prepare a paste. The paste obtained above is uniformly applied to a current collector made of a nickel metal porous substrate having a porosity of about 95% and dried so that the porosity of the positive electrode active material is 50%. A positive electrode plate coated over an area of 5 cm × 5 cm was obtained. At this time, the coating amount was adjusted so that nickel hydroxide particles corresponding to 4 Ah were included in the active material.

(3) 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 on a current collector made of copper punching metal, and the porosity was about A negative electrode plate was obtained in which the active material portion was coated over an area of 5 cm × 5 cm at 50%. At this time, the coating amount was adjusted so that the zinc oxide powder corresponding to the positive electrode plate capacity of 4 Ah was included in the active material.

(4) Battery assembly Using the positive electrode plate, the negative electrode plate, and the separator with a porous substrate obtained above, a nickel zinc secondary battery as shown in FIG. 7 was assembled in the following procedure.

  First, a rectangular parallelepiped case body made of ABS resin with the case upper lid removed was prepared. A separator with a porous substrate (a hydrotalcite film on an alumina substrate) was inserted near the center of the case body, and three sides thereof were fixed to the inner wall of the case body using a commercially available adhesive. The positive electrode plate and the negative electrode plate were inserted into the positive electrode chamber and the negative electrode chamber, respectively. At this time, the positive electrode plate and the negative electrode plate were arranged so that the positive electrode current collector and the negative electrode current collector were in contact with the inner wall of the case body. A 6 mol / L aqueous KOH solution in an amount that sufficiently hides the positive electrode active material coating portion was injected into the positive electrode chamber as an electrolyte. The liquid level in the positive electrode chamber was about 5.2 cm from the case bottom. On the other hand, in the negative electrode chamber, not only the negative electrode active material coating part was sufficiently hidden, but also an excessive amount of 6 mol / L KOH aqueous solution was injected as an electrolyte considering the amount of water expected to decrease during charging. . The liquid level in the negative electrode chamber was about 6.5 cm from the case bottom. The terminal portions of the positive electrode current collector and the negative electrode current collector were connected to external terminals at the top of the case. The case upper lid was fixed to the case body by heat sealing, and the battery case container was sealed. In this way, a nickel zinc secondary battery was obtained. In this battery, since the size of the separator is 5 cm wide × 8 cm high, and the size of the active material coated portion of the positive electrode plate and the negative electrode plate is 5 cm wide × 5 cm high, the positive electrode chamber and the negative electrode The space equivalent to 3 cm above the chamber can be said to be the positive electrode side excess space and the negative electrode side excess space.

(5) Evaluation The produced nickel zinc secondary battery was subjected to constant current charging for 10 hours at a current of 0.4 mA corresponding to 0.1 C with a design capacity of 4 Ah. After charging, no deformation of the case or leakage of the electrolyte was observed. When the amount of the electrolyte after charging was observed, the electrolyte level in the positive electrode chamber was about 7.5 cm from the bottom of the case, and the electrolyte level in the negative electrode chamber was about 5.2 cm from the bottom of the case. It was. Although the positive electrode chamber electrolyte increased and the negative electrode chamber electrolyte decreased due to charging, there was sufficient electrolyte in the negative electrode active material coating part, and the applied positive electrode active material and negative electrode active material were charged and discharged. The electrolyte that causes a sufficient charge / discharge reaction could be held in the case.

Example 3 (Reference): Preparation of a zinc-air secondary battery (1) Preparation of separator with porous substrate As a separator with a porous substrate (hereinafter simply referred to as a separator), an alumina substrate was prepared in the same procedure as in Example 1. An upper hydrotalcite membrane was prepared.

(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) Battery assembly Using the obtained air electrode with separator, negative electrode plate, and third electrode, a horizontal-type zinc-air secondary battery as shown in FIG. 9A is produced by 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. Seal the opening of the resin container with an air electrode with a separator so that the air electrode side is on the outside, and apply a commercially available adhesive to the outer periphery of the opening to provide air tightness and liquid tightness. Stop and bond. 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 134 can be brought into contact with the third electrode 138 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. .

10, 30, 50 Nickel zinc secondary battery 12, 22, 32, 42, 52, 62 Porous base material 14, 34, 54 Positive electrode 15a, 26a, 36a, 46a, 56a, 66a Positive electrode internal current collector 15b, 26b , 36b, 46b, 56b, 66b Positive electrode external current collector 16, 26, 36, 46, 56, 66 Negative electrode 17a, 27a, 38a, 48a, 58a, 68a Negative electrode internal current collector 17b, 27b, 38b, 48b, 58b , 68b Negative electrode external current collector 18, 28, 38, 48, 58, 68 Hydroxide ion conductive ceramic separator 20, 40, 60 Zinc air secondary battery 24, 44, 64 Air electrode 110 Nickel zinc secondary battery 112 Positive electrode 113 Positive electrode current collector 114 Positive electrode electrolyte 116 Negative electrode
117 Negative electrode current collector 118 Negative electrode electrolyte 120 Ceramic separator 122 Container 124 Positive electrode chamber 125 Positive electrode side excess space 126 Negative electrode chamber 127 Negative electrode side excess space 128 Porous substrate 130 Zinc air secondary battery 132 Air electrode 134 Negative electrode 136 Electrolyte 138 Third electrode 140 Ceramic separator 142 Positive electrode current collector 144 Negative electrode current collector 146 Container 146a Opening 148 Porous substrate

Claims (16)

A secondary battery using a hydroxide ion conductive ceramic separator,
A columnar porous substrate having a first end surface and a second end surface facing each other and an outer peripheral surface connecting outer peripheral edges of these end surfaces, and from the first end surface toward the second end surface and / or A porous substrate provided with a plurality of cell holes provided in parallel to each other from the second end surface toward the first end surface;
A positive electrode and a negative electrode that are alternately arranged in the plurality of cell holes for each hole or for each hole row;
A positive electrode internal current collector inserted into the positive electrode and extending to the first end surface or the outer peripheral surface;
A negative electrode internal current collector inserted into the negative electrode and extending to the second end surface, the outer peripheral surface or the first end surface;
A hydroxide ion conductive ceramic separator formed on an inner wall surface of the cell hole and separating the positive electrode and / or the negative electrode from the porous substrate;
An alkaline electrolyte impregnated in the positive electrode and / or the negative electrode and the porous substrate;
A secondary battery comprising:   The cell holes are non-through holes, and the porous base material has a honeycomb shape regularly provided with the plurality of non-through holes, and the non-through holes are formed from the first end surface toward the second end surface. The positive electrode and the positive electrode internal current collector are accommodated in the through hole, and the negative electrode and the negative electrode internal current collector are accommodated in the non-through hole formed from the second end surface toward the first end surface. The secondary battery according to claim 1, wherein the positive electrode internal current collector and the negative electrode internal current collector are extended to opposite end surfaces.   A positive external current collector provided on the first end face and connected to ends of the plurality of positive internal collectors; and an end of the negative internal current collector provided on the second end face; The secondary battery according to claim 2, further comprising a negative electrode external current collector to be connected.   The cell hole is a through-hole, the porous substrate is a monolithic shape regularly provided with the plurality of through-holes, and the positive electrode internal current collector inserted into the positive electrode has the porous group The negative electrode internal current collector that extends to the outer peripheral surface through a slit formed in the material and is inserted into the negative electrode is connected to the outer peripheral surface through another slit formed in the porous substrate. The secondary battery according to claim 1, which extends to   A positive external current collector provided on the outer peripheral surface and connected to ends of the positive internal current collectors; and provided in a region of the outer peripheral surface where the positive external current collector does not exist, The secondary battery according to claim 4, further comprising a negative electrode external current collector connected to an end of the negative electrode internal current collector.   The secondary according to claim 5, wherein the positive electrode external current collector is provided on a specific side of the outer peripheral surface, and the negative electrode external current collector is provided on the opposite side of the outer peripheral surface from the positive electrode external current collector. battery.   The secondary battery according to any one of claims 1 to 6, wherein the hydroxide ion conductive ceramic separator is in the form of a film or a layer that is so dense that it does not have water permeability.   The secondary battery according to any one of claims 1 to 7, wherein the hydroxide ion conductive ceramic separator is made of an inorganic solid electrolyte body having hydroxide ion conductivity.   The secondary battery according to claim 8, 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 secondary battery according to claim 8, comprising a layered double hydroxide having a basic composition of: In the general ^{formula, M 2+} comprises ^{Mg 2+, M 3+} comprises ^{Al 3+, A n-is} OH ^- containing and / or _CO ^{3 2-} and secondary battery according to claim 10.   The secondary battery according to claim 8, wherein the inorganic solid electrolyte body is densified by hydrothermal treatment.   The secondary battery according to claim 1, wherein the negative electrode includes zinc, a zinc alloy, and / or a zinc compound, whereby the secondary battery is configured as a zinc secondary battery.   The secondary battery according to claim 13, wherein the positive electrode is an air electrode, and the positive electrode internal current collector has air permeability, whereby the secondary battery is configured as a zinc-air secondary battery.   The secondary battery according to claim 14, wherein the positive electrode external current collector has air permeability. The secondary battery according to claim 13, wherein the positive electrode comprises the nickel hydroxide and / or nickel oxyhydroxide, whereby the secondary battery is configured as a nickel zinc secondary battery.