WO2018135117A1 - Separator structure, nickel-zinc secondary battery, and zinc-air secondary battery - Google Patents

Abstract

Disclosed is a separator structure for a zinc secondary battery. This separator structure is provided with: a composite plate comprising a layered double hydroxide (LDH) separator and a porous substrate provided to one side of the LDH separator; and a resin outer frame having an opening in which the composite plate is to be fitted. The resin outer frame has a recess for locking the porous substrate side of the composite plate along the inner periphery of the resin outer frame, and the recess and the composite plate are seal-jointed with an adhesive. The porous substrate has a thickness of at least 100 μm, and the portion of the porous substrate that faces the recess is impregnated with the adhesive down to a depth of at least 100 μm from the surface of the porous substrate. The present invention makes it possible to improve reliability and durability of a separator structure in which a porous substrate-equipped LDH separator is provided in a resin outer frame.

Description

Separator structure, nickel-zinc secondary battery, and zinc-air secondary battery

The present invention relates to a separator structure, a nickel zinc secondary battery, and a zinc-air secondary battery.

In zinc secondary batteries such as nickel zinc secondary battery and air zinc secondary battery, metallic zinc is deposited in a dendrite shape from the negative electrode during charging, and reaches the positive electrode through the voids of a separator such as a nonwoven fabric. It is known to cause a short circuit. Such short circuit due to zinc dendrite repeatedly shortens the charge / discharge life.

In order to cope with the above problem, a battery having a layered double hydroxide (LDH) separator that selectively penetrates hydroxide ions and prevents penetration of zinc dendrite has been proposed. For example, Patent Document 1 (International Publication No. 2013/118561) discloses that an LDH separator is provided between a positive electrode and a negative electrode in a nickel zinc secondary battery. Patent Document 2 (International Publication No. 2016/076047) discloses a separator structure including an LDH separator fitted or joined to a resin outer frame, and the LDH separator is gas impermeable and It is disclosed that it has high density enough to have water impermeability. This document also discloses that an LDH separator is used in the form of a composite plate combined with a porous substrate.

Further, Patent Document 3 (International Publication No. 2016/039349) discloses a configuration in which an LDH separator is bonded to a resin outer frame via an adhesive. In this document, from the viewpoint of adhesiveness and alkali resistance, epoxy resin adhesives, natural resin adhesives, modified olefin resins are used for resin outer frames made of ABS resin, modified polyphenylene ether, and polypropylene resin. An adhesive selected from a base adhesive and a modified silicone resin adhesive is used.

International Publication No. 2013/118561 International Publication No. 2016/076047 International Publication No. 2016/039349

The LDH separator as described above can effectively prevent a short circuit between positive and negative electrodes due to zinc dendrite in a nickel-zinc battery, but further improvement in the performance of the nickel-zinc battery is desired. In particular, in order to more effectively avoid a short circuit between the positive and negative electrodes due to zinc dendrite, it is desired to completely block the electrolyte solution between the positive and negative electrodes. In this respect, also in the separator structure as disclosed in Patent Documents 2 and 3, from the viewpoint of improving the reliability, the bonding portion between the composite plate including the LDH separator and the porous substrate and the resin outer frame Improvement of airtightness or liquid tightness is desired. In addition, it is also desired to improve the durability of the bonded portion in long-term use involving battery charge / discharge operation in an alkaline electrolyte.

In the present invention, when sealing and bonding a composite plate including an LDH separator and a porous base material to a resin outer frame with an adhesive, the porous base material side of the composite plate and the concave portion of the resin outer frame are now used. The inventors obtained knowledge that an LDH separator structure excellent in reliability and durability can be provided by facing the surface and deeply soaking the adhesive into the porous substrate.

Therefore, an object of the present invention is to improve reliability and durability in a separator structure including an LDH separator with a porous substrate in a resin outer frame.

According to one aspect of the present invention, there is provided a separator structure for a zinc secondary battery,
A composite plate comprising a layered double hydroxide (LDH) separator and a porous substrate provided on one side of the LDH separator;
A resin outer frame having an opening into which the composite plate is fitted;
With
The resin outer frame has a recess that locks the porous substrate side of the composite plate along its inner periphery, and the recess and the composite plate are sealed and bonded with an adhesive,
The porous substrate has a thickness of 100 μm or more, and a portion of the porous substrate that faces the recess is infiltrated with the adhesive over a depth of 100 μm or more from the surface of the porous substrate. A separator structure is provided.

According to another aspect of the invention, a positive electrode comprising nickel hydroxide and / or nickel oxyhydroxide,
A negative electrode comprising zinc, a zinc alloy and / or zinc oxide;
An electrolyte containing an alkali metal hydroxide aqueous solution;
Separating the positive electrode and the negative electrode so that hydroxide ions can be conducted; and
A nickel zinc secondary battery is provided.

According to another aspect of the invention, an air electrode;
A negative electrode comprising zinc, a zinc alloy and / or zinc oxide;
An electrolyte containing an alkali metal hydroxide aqueous solution;
The separator structure for separating the air electrode and the negative electrode so that hydroxide ions can be conducted; and
A zinc-air secondary battery is provided.

It is sectional drawing which shows the separator structure of this invention typically. FIG. 2 is an enlarged view microscopically illustrating an adhesion portion of the separator structure shown in FIG. 1. It is a SEM image which shows the surface microstructure of the functional layer produced in Example A1. It is a SEM image which shows the cross-sectional microstructure of the functional layer produced in Example A1. It is a cross-sectional SEM image of the porous base material soaked with the adhesive agent produced in Example B1. FIG. 3B is a cross-sectional SEM image obtained by magnifying and observing the penetration interface portion shown in FIG. 3A. It is the photograph which image | photographed the porous base material infiltrated with the adhesive agent produced in Example B1 from right above. It is a cross-sectional SEM image of the porous base material soaked with the adhesive agent produced in Example B5 (comparative example). FIG. 4B is a cross-sectional SEM image obtained by magnifying and observing the penetration interface portion shown in FIG. 4A. It is the photograph which image | photographed the porous base material infiltrated with the adhesive agent produced in Example B5 (comparative example) from right above. FIG. 5 is an exploded perspective view of a measurement sealed container used in a denseness determination test of Examples B1 to B5. FIG. 3 is a schematic cross-sectional view of a measurement system used in a denseness determination test of Examples B1 to B5. It is a conceptual diagram which shows an example of the He transmittance | permeability measurement system used in Examples B1-B5. 6B is a schematic cross-sectional view of a sample holder used in the measurement system shown in FIG. It is a figure which shows the structure of the sample produced in the tensile strength test of Examples B1-B6. It is a schematic cross section which shows the conventional separator structure. It is an enlarged view of the adhesion part of the separator structure shown by FIG. 8A. FIG. 8B is a schematic cross-sectional view showing a separator structure in which the directions of the LDH separator and the porous substrate are reversed in the separator structure shown in FIG. 8A. It is an enlarged view of the junction part of the separator structure shown by FIG. 9A.

Separator structure The separator structure of the present invention is used for a zinc secondary battery. In this specification, the zinc secondary battery is a nickel zinc secondary battery, a silver zinc oxide secondary battery, a manganese zinc secondary battery, a zinc-air secondary battery, and various other types of alkaline zinc secondary batteries, such as LDH separators. Can be applied to various zinc secondary batteries. In particular, a nickel zinc secondary battery and a zinc-air secondary battery are preferable, and a nickel zinc battery is particularly preferable. A battery to which the separator structure can be applied may be a unit battery having a pair of a positive electrode and a negative electrode, or a stacked battery including two or more pairs of a positive electrode and a negative electrode, that is, two or more unit cells. May be. In addition, the stacked battery may be a series-type stacked battery or a parallel-type stacked battery.

A zinc secondary battery in which the separator structure of the present invention is incorporated includes a positive electrode, a negative electrode, an electrolytic solution, and a separator structure. What is necessary is just to select a positive electrode and a negative electrode suitably according to the kind of secondary battery, respectively. For example, in the case of a nickel zinc secondary battery, the positive electrode includes nickel hydroxide and / or nickel oxyhydroxide, and the negative electrode includes zinc, a zinc alloy, and / or zinc oxide. In the case of a zinc-air secondary battery, the positive electrode is an air electrode, and the negative electrode contains zinc, a zinc alloy, and / or zinc oxide. The separator structure is a structure including an LDH separator, and is provided so as to isolate the positive electrode and the negative electrode so as to conduct hydroxide ions. A typical electrolyte includes an aqueous alkali metal hydroxide solution.

1A and 1B are schematic cross-sectional views of the separator structure of the present invention. As shown in FIGS. 1A and 1B, the separator structure 10 includes a composite plate 12 and a resin outer frame 18. The composite plate 12 includes an LDH separator 14 and a porous substrate 16 provided on one side of the LDH separator 14. The resin outer frame 18 includes an opening 18a, and the composite plate 12 is fitted into the opening 18a. The resin outer frame 18 has a concave portion 18b that locks the porous substrate 16 side of the composite plate 12 along its inner periphery, and the concave portion 18b and the composite plate 12 are sealed and bonded with an adhesive 20. . The porous substrate 16 has a thickness of 100 μm or more, and the portion facing the concave portion 18b of the porous substrate 16 is 100 μm from the surface of the porous substrate 16 as depicted in an enlarged view in FIG. The adhesive 20 is soaked over the depth D described above. In the present specification, the fact that the adhesive 20 soaks into the porous substrate 16 means that the pores in the porous substrate 16 are filled with the adhesive 20. As described above, when the composite plate 12 including the LDH separator 14 and the porous base material 16 is sealed and bonded to the resin outer frame 18 with the adhesive 20, the porous base material 16 side of the composite plate 12 is connected to the resin outer frame. Reliability and durability can be improved by facing the 18 recesses 18b and deeply soaking the adhesive 20 into the porous substrate 16. These advantages can be explained as follows.

As a premise, as shown in FIG. 8A, a separator structure in which the composite plate 12 is sealed and bonded to the resin outer frame 18 with the LDH separator 14 side facing the concave portion 18b of the resin outer frame 18 is already present. It is known (see, for example, Patent Document 2). That is, a structure in which the LDH separator 14 side of the composite plate 12 is positioned on the narrow side of the opening 18a and the porous substrate 16 side of the composite plate 12 is positioned on the wide side of the opening 18a is already known. In the case of this arrangement, the LDH separator 14 and the resin outer frame 18 (particularly, the recess 18b) are bonded via the adhesive 20, so that a dense and excellent airtight or liquid-tight property as shown in FIG. 8B. Since the area that can be bonded to the LDH separator 14 is large (see the portion surrounded by the dotted line in the figure), it is easy to ensure airtightness or liquid-tightness in the bonded portion, and therefore the reliability of the bonded portion is increased. On the other hand, since the LDH separator 14 for preventing the penetration of zinc dendrite faces the negative electrode 24, the zinc dendrite extending from the negative electrode 24 during charging peels off the adhesive 20 (tensile direction; FIG. 8A). In this case, the LDH separator 14 is pushed in the direction indicated by the arrow in FIG.

In order to cope with such a problem, as shown in FIG. 9A, the direction of the composite plate 12 is reversed, specifically, the porous base material 16 side is opposed to the concave portion 18b of the resin outer frame 18. A configuration in which the resin outer frame 18 is sealed and joined is conceivable. That is, the LDH separator 14 side of the composite plate 12 is positioned on the wide side of the opening 18a, and the porous substrate 16 side of the composite plate 12 is positioned on the narrow side of the opening 18a. In this arrangement, the zinc dendrite that develops from the negative electrode 24 during charging grows in a direction (compression direction; indicated by an arrow in FIG. 9A) that presses the bonded portion toward the concave portion 18b. improves. However, as shown in FIG. 9B, the contact area between the dense LDH separator 14 excellent in airtightness or liquid tightness and the adhesive 20 becomes extremely small (see the portion surrounded by a dotted line in the figure). It becomes difficult to ensure airtightness or liquid tightness, and the reliability of the bonded portion is impaired. Thus, simply reversing the orientation of the composite plate 12 with respect to the orientation of the prior art as shown in FIGS. 8A and 8B improves reliability by ensuring the airtightness or liquid tightness of the bonded portion. It can be said that it is difficult to achieve both improvement in durability against discharge.

In response to such a technical problem, in the separator structure 10 of the present invention, as shown in FIGS. 1A and 1B, the portion of the porous substrate 16 that faces the recess 18 b is the surface of the porous substrate 16. To 100 μm or more of the depth D is adopted. Thus, the porous substrate 16 side of the composite plate 12 is opposed to the concave portion 18b of the resin outer frame 18, and the adhesive 20 is deeply soaked into the porous substrate 16, thereby improving reliability and durability. Can be improved. That is, by disposing the composite plate 12 in the above-described direction, the zinc dendrite that precipitates during charging grows in a direction (compression direction) that presses the bonded portion toward the concave portion 18b. improves. Further, since the adhesive 20 (preferably an alkali-resistant resin) is deeply infiltrated into the porous substrate 16, the porous substrate 16 is porous even if the contact area between the LDH separator 14 and the adhesive 20 is extremely small. Airtightness and liquid-tightness can be ensured by the portion filled with the adhesive 20 of the base material 16, and high reliability of the bonded portion is ensured. In addition, since the adhesive 20 penetrates deeply into the porous base material 16, an improvement in the adhesive strength can be expected. Although this structure can be said to be a structure in which the adhesive 20 (preferably an alkali-resistant resin) has penetrated the end face of the porous substrate 16, the adhesive 20 is bonded to the composite plate 12 (especially the porous substrate 16). Or the composite plate 12 (especially the porous substrate 16) before bonding. In any case, it can be said that the adhesion interface in the separator structure 10 of the present invention is not an interface where the surfaces are merely two-dimensionally bonded, but is more difficult to peel off due to a more three-dimensional adhesion structure due to the penetration of the adhesive. .

The composite plate composite plate 12 includes an LDH separator 14 and a porous substrate 16 provided on one side of the LDH separator 14.

The LDH separator 14 is a separator containing layered double hydroxide (LDH), and separates the positive electrode plate and the negative electrode plate so as to conduct hydroxide ions when incorporated in a zinc secondary battery. That is, the LDH separator 14 functions as a hydroxide ion conductive separator. A preferred LDH separator 14 is gas impermeable and / or water impermeable. In other words, the LDH separator 14 is preferably so dense that it has impermeability and / or water impermeability. In the present specification, “having gas impermeability” means that the gas impermeability is evaluated by the “denseness determination test” employed in the evaluation 4 of Example A1 described later or a method or configuration equivalent thereto. This means that even if helium gas is brought into contact with one surface side of the measurement object (that is, LDH separator 14) in water at a differential pressure of 0.5 atm, no bubbles are generated due to helium gas from the other surface side. . Further, in the present specification, “having water impermeability” means that water that contacts one surface side of the measurement object (for example, LDH separator) does not permeate the other surface side (see, for example, Patent Document 2). ). That is, the fact that the LDH separator 14 has gas impermeability and / or water impermeability means that the LDH separator 14 has a high degree of denseness that does not allow gas or water to pass through, and has water permeability. It means not a porous film or other porous material. By doing so, the LDH separator 14 can selectively pass only hydroxide ions due to its hydroxide ion conductivity, and can exhibit a function as a battery separator. 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. Since the LDH separator 14 has hydroxide ion conductivity, it enables efficient transfer of necessary hydroxide ions between the positive electrode plate and the negative electrode plate, and realizes a charge / discharge reaction in the positive electrode plate and the negative electrode plate. Can do.

The LDH separator 14 preferably has a He permeability per unit area of 10 cm / min · atm or less, more preferably 5.0 cm / min · atm or less, and even more preferably 1.0 cm / min · atm or less. . It can be said that the LDH separator having the He permeability in such a range has extremely high density. Therefore, an LDH separator having a He permeability of 10 cm / min · atm or less can prevent substances other than hydroxide ions from passing at a high level when applied as a separator in a zinc secondary battery. For example, permeation of zinc ions and / or zincate ions in the electrolytic solution can be extremely effectively suppressed. In this way, it is considered in principle that the transmission of zinc ions and / or zincate ions is remarkably suppressed, so that the growth of zinc dendrite can be effectively suppressed when used in a zinc secondary battery. For the He permeability, a process of supplying He gas to one side of the separator or the functional layer to allow the He gas to pass through the separator or the functional layer, and calculating the He permeability to evaluate the density of the separator or the functional layer. It is measured through the process. The He permeability is F / (P × S) using the He gas permeation amount F per unit time, the differential pressure P applied to the separator or functional layer when He gas permeates, and the membrane area S through which He gas permeates. It is calculated by the following formula. Thus, by evaluating the gas permeability using He gas, it is possible to evaluate the presence or absence of denseness at a very high level, and as a result, substances other than hydroxide ions (especially zinc dendrite growth can be performed). It is possible to effectively evaluate a high degree of denseness such that the zinc ion and / or zincate ion to be caused is not transmitted as much as possible (only a very small amount is transmitted). This is because the He gas has the smallest structural unit among a wide variety of atoms or molecules that can constitute the gas, and the reactivity is extremely low. That is, He forms He gas by a single He atom without forming a molecule. Then, by adopting the He gas permeability index defined by the above-described formula, objective evaluation regarding the denseness can be easily performed regardless of differences in various sample sizes and measurement conditions. In this way, it is possible to simply, safely and effectively evaluate whether the LDH separator has sufficiently high density suitable for a zinc secondary battery separator. The measurement of He permeability can be preferably performed according to the procedure shown in Evaluation 5 of Example A1 described later.

The LDH separator 14 preferably contains a layered double hydroxide (LDH), more preferably LDH. As is generally known, LDH is composed of a plurality of hydroxide base layers and an intermediate layer interposed between the plurality of hydroxide base layers. The hydroxide base layer is mainly composed of metal elements (typically metal ions) and OH groups. The intermediate layer of LDH is composed of anions and H ₂ O. The anion is a monovalent or higher anion, preferably a monovalent or divalent ion. Preferably, the anion in LDH comprises OH ^- and / or CO ₃ ^2- . LDH has excellent ionic conductivity due to its inherent properties.

In general, LDH is M ²⁺ _1-x M ³⁺ _x (OH) ₂ A ⁿ⁻ _{x / n} · mH ₂ O (where M ²⁺ is a divalent cation and M ³⁺ is a trivalent cation). A ⁿ⁻ is an n-valent anion, n is an integer of 1 or more, x is 0.1 to 0.4, and m is 0 or more). It is known as a representative. In the above basic composition 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- can be any anion, but preferred examples include OH ^- and CO ₃ ^2- . Accordingly, in the above basic ^{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 an arbitrary number which means the number of moles of water, and is a real number of 0 or more, typically more than 0 or 1 or more. However, the above basic composition formula is merely a formula of “basic composition” that is typically exemplified with respect to LDH in general, and the constituent ions can be appropriately replaced. For example, it may be replaced with some or all of the M ³⁺ tetravalent or higher valency cations in the basic formula, in which case, the anion A coefficient of ^n-x / n in the general formula May be changed as appropriate.

For example, the hydroxide base layer of LDH may be composed of Ni, Ti, OH groups and possibly inevitable impurities. As described above, the intermediate layer of LDH is composed of an anion and H ₂ O. The alternate layered structure of the hydroxide basic layer and the intermediate layer itself is basically the same as the commonly known alternate layered structure of LDH, but the LDH of this embodiment is mainly composed of Ni, By comprising Ti and OH groups, excellent alkali resistance can be exhibited. Although the reason is not necessarily clear, it is considered that an element (for example, Al) that is considered to be easily eluted in an alkaline solution is not intentionally or actively added to the LDH of this embodiment. Nevertheless, the LDH of this embodiment can also exhibit high ionic conductivity suitable for use as a separator for an alkaline secondary battery. Ni in LDH can take the form of nickel ions. The nickel ions in LDH are typically considered to be Ni ²⁺ , but are not particularly limited because other valences such as Ni ³⁺ may also exist. Ti in LDH can take the form of titanium ions. The titanium ion in LDH is typically considered to be Ti ⁴⁺ , but is not particularly limited because other valences such as Ti ³⁺ may also exist. Inevitable impurities are optional elements that can be inevitably mixed in the manufacturing process, and can be mixed in LDH, for example, derived from raw materials and base materials. As described above, since the valences of Ni and Ti are not necessarily certain, it is impractical or impossible to specify LDH strictly by a general formula. If it is assumed that the hydroxide base layer is mainly composed of Ni ²⁺ , Ti ⁴⁺ and OH groups, the corresponding LDH has the general formula: Ni ²⁺ _1-x Ti ⁴⁺ _x (OH) ₂ ^{An _{- 2x / n · mH 2 O}} ( ^{wherein, a n-n-valent} anion, n is an integer of 1 or more, preferably 1 or 2, 0 <x <1, preferably 0.01 ≦ x ≦ 0.5, m is 0 or more, typically greater than 0 or 1 or more real number). However, the above general formula should be construed as “basic composition” only, and other elements or ions (other valences of the same element) to the extent that elements such as Ni ²⁺ and Ti ⁴⁺ do not impair the basic characteristics of LDH. It should be understood that it can be replaced by a number of elements or ions, or elements or ions that may be inevitably mixed in the manufacturing process.

Alternatively, the hydroxide basic layer of LDH may contain Ni, Al, Ti and OH groups. As described above, the intermediate layer is composed of an anion and H ₂ O. The alternate layered structure of the hydroxide basic layer and the intermediate layer itself is basically the same as the generally known alternate layered structure of LDH, but the LDH of this embodiment uses the basic hydroxide layer of LDH as Ni, Al. By comprising a predetermined element or ion containing Ti and OH groups, excellent alkali resistance can be exhibited. The reason for this is not necessarily clear, but the LDH of this embodiment is thought to be because Al, which was previously thought to be easily eluted in an alkaline solution, is less likely to be eluted in an alkaline solution due to some interaction with Ni and Ti. It is done. Nevertheless, the LDH of this embodiment can also exhibit high ionic conductivity suitable for use as a separator for an alkaline secondary battery. Ni in LDH can take the form of nickel ions. The nickel ions in LDH are typically considered to be Ni ²⁺ , but are not particularly limited because other valences such as Ni ³⁺ may also exist. Al in LDH can take the form of aluminum ions. Aluminum ions in LDH are typically considered to be Al ³⁺ , but are not particularly limited because other valences are possible. Ti in LDH can take the form of titanium ions. The titanium ion in LDH is typically considered to be Ti ⁴⁺ , but is not particularly limited because other valences such as Ti ³⁺ may also exist. The hydroxide base layer may contain other elements or ions as long as it contains Ni, Al, Ti and OH groups. However, it is preferable that the hydroxide base layer contains Ni, Al, Ti, and OH groups as main components. That is, the hydroxide base layer is preferably mainly composed of Ni, Al, Ti and OH groups. Therefore, the hydroxide base layer is typically composed of Ni, Al, Ti, OH groups and possibly inevitable impurities. Inevitable impurities are optional elements that can be inevitably mixed in the manufacturing process, and can be mixed in LDH, for example, derived from raw materials and base materials. As described above, since the valences of Ni, Al, and Ti are not necessarily certain, it is impractical or impossible to specify LDH strictly by a general formula. If it is assumed that the hydroxide base layer is mainly composed of Ni ²⁺ , Al ³⁺ , Ti ⁴⁺ and OH groups, the corresponding LDH has the general formula: Ni ²⁺ _1-xy Al ³⁺ _x Ti ⁴⁺ _y (OH) ₂ A ⁿ⁻ _{(x + 2y) / n} · mH ₂ O (where A ⁿ⁻ is an n-valent anion, n is an integer of 1 or more, preferably 1 or 2, and 0 <x <1, preferably 0.01 ≦ x ≦ 0.5, 0 <y <1, preferably 0.01 ≦ y ≦ 0.5, 0 <x + y <1, m is 0 or more, typically 0. It can be represented by a basic composition that exceeds or is one or more real numbers. However, the above general formula should be construed as “basic composition” only, and other elements or ions (of the same element) such that Ni ²⁺ , Al ³⁺ , Ti ^{4+ and the} like do not impair the basic characteristics of LDH. It should be understood that it can be replaced by other valence elements or ions or elements or ions that may be inevitably mixed in the manufacturing process.

The LDH separator 14 is combined with the porous substrate 16. That is, the LDH separator 14 may be a composite material including an LDH film and a porous substrate, or may be a composite material in which LDH is filled in the pores of the porous substrate (in this case, LDH There may be no film). A combination of both may also be used. That is, a configuration in which part of the LDH film is incorporated in the pores of the porous substrate may be used. In this case, the functional layer exhibiting the separator function is composed of a film-shaped portion made of an LDH film and a composite portion made of LDH and a porous substrate.

It goes without saying that the porous substrate 16 has water permeability, and therefore, when incorporated in a zinc secondary battery, the electrolyte solution can reach the LDH separator 14. As a result, the hydroxide ions can be stably held by the LDH separator 14. Further, since the strength can be imparted by the porous substrate 16, the LDH separator 14 can be made thin to reduce the resistance. The thickness of the porous substrate is 100 μm or more, preferably 100 to 600 μm, more preferably 100 to 500 μm, still more preferably 100 to 400 μm, particularly preferably 100 to 350 μm, and most preferably 100 to 300 μm. With such a thickness, sufficient strength can be imparted, and a deeper penetration portion of the adhesive 20 can be secured, thereby improving the air tightness or liquid tightness of the adhesive portion.

The porous substrate 16 is preferably composed of at least one selected from the group consisting of a ceramic material, a metal material, and a polymer material, more preferably a ceramic material and / or a polymer material, still more preferably. It is a polymer material. 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, and any combination thereof, and more preferable. Is alumina, zirconia, titania, and any combination thereof, particularly preferably alumina and zirconia, most preferably alumina. When these porous ceramics are used, it is easy to form the LDH separator 14 having excellent denseness. Preferred examples of the metal material include aluminum, zinc, and nickel. Preferred examples of the polymer material include polystyrene, polyethersulfone, polypropylene, epoxy resin, polyphenylene sulfide, hydrophilic fluororesin (tetrafluorinated resin: PTFE, etc.), cellulose, nylon, polyethylene, and any combination thereof. Is mentioned. 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.

Preferably, the LDH separator 14 has an LDH film composed of an aggregate of a plurality of LDH plate-like particles, and the plurality of LDH plate-like particles have their plate surfaces on the surface of the porous substrate 16 (with a porous structure). It is oriented in a direction that intersects perpendicularly or obliquely with the main surface of the porous substrate when macroscopic observations resulting from negligible microscopic unevenness are observed. The LDH film may be at least partially incorporated in the pores of the porous base material 16, and in that case, LDH plate-like particles may also exist in the pores of the porous base material 16. Although LDH crystals are known to have the form of plate-like particles having a layered structure, the vertical or oblique orientation is a very advantageous property for the LDH separator 14. This is because the oriented LDH-containing separator has a much higher hydroxide ion conductivity in the direction in which the LDH plate-like particles are oriented (that is, the direction parallel to the LDH layer) than the conductivity in the direction perpendicular thereto. This is because of the conductivity anisotropy. In fact, it is already known that in an oriented bulk body of LDH, the conductivity (S / cm) in the orientation direction is one digit higher than the conductivity (S / cm) in the direction perpendicular to the orientation direction. That is, the above vertical or oblique alignment maximizes or significantly extracts the conductivity anisotropy that the LDH alignment body can have in the layer thickness direction (that is, the direction perpendicular to the surface of the LDH film or the porous substrate 16). As a result, the conductivity in the layer thickness direction can be maximized or significantly increased. In addition, since the LDH film has a film form, lower resistance than the bulk form LDH can be realized. An LDH film having such an orientation easily conducts hydroxide ions in the layer thickness direction.

The LDH separator 14 preferably has a thickness of 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 LDH separator 14 can be reduced. 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 separator 14 is not particularly limited because it varies depending on the application, but in order to ensure a certain degree of rigidity 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 manufacturing method of the composite plate 12, that is, the LDH separator 14 combined with the porous substrate 16 is not particularly limited, and is manufactured by referring to a known manufacturing method of an LDH separator (for example, Patent Documents 1 to 3). be able to.

Resin Outer Frame The resin outer frame 18 has an opening 18a, and the composite plate 12 is fitted into the opening 18a. Moreover, the resin outer frame 18 has a recess 18b that locks the porous substrate 16 side of the composite plate 12 along its inner periphery. Accordingly, the size of the opening 18a is slightly smaller than that of the composite plate 12, but the size of the contour shape of the recess 18b is equal to or slightly larger than that of the composite plate 12. The presence of the resin outer frame 18 can reinforce the end of the composite plate 12, thereby preventing damage to the end of the composite plate 12 and improving reliability, and handling the composite plate 12. It becomes easy. Therefore, the assembly of the zinc secondary battery is facilitated. The resin outer frame 18 itself can also contribute to the prevention of zinc dendrite penetration and extension. The resin constituting the resin outer frame 18 is preferably a resin having resistance to alkali metal hydroxide such as potassium hydroxide, more preferably polyolefin resin, ABS resin, polypropylene (PP) resin, polyethylene (PE). A resin or a modified polyphenylene ether, more preferably an ABS resin, a polypropylene (PP) resin, a polyethylene (PE) resin, or a modified polyphenylene ether, and particularly preferably an ABS resin or a modified polyphenylene from the viewpoint of alkali resistance and adhesiveness. Ether (m-PPE) and polypropylene (PP) resins. The modified polyphenylene ether may be a compound (for example, m-PPE / PS) combined with another polymer (for example, polystyrene).

The concave portion 18 b of the adhesive resin outer frame 18 and the composite plate 12 are sealed and bonded with an adhesive 20. The portion of the porous substrate 16 that faces the concave portion 18b is infiltrated with the adhesive 20 from the surface of the porous substrate 16 over a predetermined depth D. The penetration depth D of the adhesive 20 into the porous substrate 16 is 100 μm or more from the surface of the porous substrate 16, preferably 100 to 600 μm, more preferably 100 to 500 μm, still more preferably 100 to 400 μm, Particularly preferred is 100 to 350 μm, and most preferred is 100 to 300 μm. Such a penetration depth can be realized by selecting an adhesive having a low viscosity. This is because an adhesive having a low viscosity is likely to enter the pores of the porous substrate 16. The adhesive having a low viscosity can be, for example, an adhesive that does not contain a thickener or a filler (for example, Si component) or has a small content of the thickener or the filler.

The adhesive 20 preferably contains a resin having alkali resistance in order to prevent deterioration in an alkaline electrolyte. From this viewpoint, the preferable adhesive 20 is at least one selected from the group consisting of an epoxy resin adhesive, a natural resin adhesive, a modified olefin resin adhesive, and a modified silicone resin adhesive. These adhesives are all excellent in adhesion to both ceramics and resin.

An epoxy resin adhesive is preferable because it is particularly excellent in alkali resistance. The epoxy resin adhesive is not limited to what is called an epoxy adhesive as long as it is an adhesive mainly composed of an epoxy resin, and various epoxy adhesives such as an epoxy amide adhesive and an epoxy-modified silicone adhesive. An agent may be used. Moreover, either a one-component type (heat curing type) or a two-component mixed type may be used. Epoxy resins are generally high in crosslink density, and thus have low water absorption, and are considered to suppress reaction with an alkaline electrolyte (for example, KOH aqueous solution). In particular, the epoxy resin-based adhesive preferably has a glass transition temperature Tg of 40 ° C. or higher, more preferably 43 ° C. or higher, and further preferably 45 to 95 ° C. By having such a high glass transition temperature Tg, alkali resistance (particularly alkali resistance at high temperatures) is further improved. Examples of epoxy resin adhesives include epoxy amide adhesives, epoxy modified silicone adhesives, epoxy adhesives, epoxy modified amide adhesives, epoxy polysulfide adhesives, epoxy acid anhydride adhesives, and epoxy nitrile adhesives. However, epoxy amide adhesives and epoxy adhesives are particularly preferred.

The above-mentioned epoxy resin adhesive is a thermosetting adhesive, but a natural resin adhesive and / or a modified olefin resin adhesive can also be used as the thermoplastic resin adhesive. In this case, the thermoplastic resin-based adhesive preferably has a softening point of 80 ° C. or higher (specifically, an R & B softening point), more preferably 90 ° C. or higher, and still more preferably 95 to 160 ° C. In the case of a thermoplastic resin, the higher the softening point, the more difficult it is to react. Therefore, the alkali resistance is improved at the above temperature.

As a result of sealing and joining the resin outer frame 18 and the composite plate 12 with the adhesive 20 as described above, the separator structure 10 as a whole can have gas impermeability and / or water impermeability.

The present invention will be described more specifically with reference to the following examples.

Example A1 : Production of composite plate containing LDH separator and porous substrate A functional layer containing LDH and a composite material were produced and evaluated by the following procedure. The functional layer in this example is a layer corresponding to an “LDH separator”, specifically, a layer including an LDH film and LDH in a porous substrate. The composite material in this example corresponds to a “composite plate”.

(1) Preparation of porous substrate 70 parts by weight of a dispersion medium (xylene: butanol = 1: 1) and binder (polyvinyl butyral: Sekisui Chemical) with respect to 100 parts by weight of alumina powder (AES-12, manufactured by Sumitomo Chemical Co., Ltd.) BM-2 manufactured by Kogyo Co., Ltd. 11.1 parts by weight, 5.5 parts by weight of a plasticizer (DOP: manufactured by Kurokin Kasei Co., Ltd.), and 2.9 parts by weight of a dispersant (Rheodor SP-O30 manufactured by Kao Corporation) The mixture was stirred and degassed by stirring under reduced pressure to obtain a slurry. The slurry was molded into a sheet shape on a PET film using a tape molding machine so that the film thickness after drying was 220 μm to obtain a sheet molded body. The obtained molded body was cut out to have a size of 2.0 cm × 2.0 cm × thickness 0.022 cm and fired at 1300 ° C. for 2 hours to obtain an alumina porous substrate.

For the obtained porous substrate, the porosity of the porous substrate was measured by the Archimedes method and found to be 40%.

Further, when the average pore diameter of the porous substrate was measured, it was 0.3 μm. 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. All obtained pore diameters are arranged in order of size, and the top 15 points and the bottom 15 points are arranged in order from the average value. An average value for two visual fields was calculated at 30 points to obtain an average pore diameter. For length measurement, the length measurement function of SEM software was used.

(2) Polystyrene spin coating and sulfonation 0.6 g of a polystyrene substrate was dissolved in 10 ml of a xylene solution to prepare a spin coating solution having a polystyrene concentration of 0.06 g / ml. 0.1 ml of the obtained spin coating solution was dropped onto an alumina porous substrate and applied by spin coating at a rotation speed of 8000 rpm. This spin coating was performed for 200 seconds including dripping and drying. The porous substrate coated with the spin coating solution was immersed in 95% sulfuric acid at 25 ° C. for 4 days for sulfonation.

(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 70 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 an aqueous raw material solution.

(4) Film formation by hydrothermal treatment A Teflon (registered trademark) sealed container (with an internal volume of 100 ml, the outside is a stainless steel jacket) and the raw material aqueous solution prepared in (3) above and the porous substrate sulfonated in (2) above Was enclosed together. 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, a hydrothermal treatment was performed at a hydrothermal temperature of 70 ° C. for 168 hours (7 days) to form an LDH alignment film on the substrate surface. After a lapse of a predetermined time, the substrate was taken out from the sealed container, washed with ion-exchanged water, dried at 70 ° C. for 10 hours, and a part of the functional layer containing LDH was incorporated into the porous substrate. Got in shape. The thickness of the functional layer obtained was about 3 μm (including the thickness of the portion incorporated in the porous substrate).

(5) Evaluation result The following evaluation was performed with respect to the obtained functional layer or composite material.

Evaluation 1 : Identification of functional layer The crystal phase of the functional layer was measured with an X-ray diffractometer (RINT TTR III manufactured by Rigaku Corporation) under the measurement conditions of voltage: 50 kV, current value: 300 mA, measurement range: 10 to 70 °. As a result, an XRD profile was obtained. About the obtained XRD profile, JCPDS card NO. Identification was performed using a diffraction peak of LDH (hydrotalcite compound) described in 35-0964. As a result, it was identified from the obtained XRD profile that the functional layer was LDH (hydrotalcite compound).

Evaluation 2 : Observation of microstructure The surface microstructure of the functional layer was observed with a scanning electron microscope (SEM, JSM-6610LV, manufactured by JEOL) at an acceleration voltage of 10 to 20 kV. Further, after obtaining a cross-sectional polished surface of a functional layer (a film-shaped portion made of an LDH film and a composite portion made of LDH and a base material) with an ion milling device (manufactured by Hitachi High-Technologies Corporation, IM4000) The structure was observed by SEM under the same conditions as the observation of the surface microstructure, and as a result, the SEM images of the surface microstructure and the cross-sectional microstructure of the functional layer were as shown in FIGS. As shown, it was found that the functional layer was composed of a film-shaped portion made of an LDH film and a composite portion made of LDH and a porous substrate located under the film-shaped portion. The LDH constituting the part is composed of an aggregate of a plurality of plate-like particles, and the plurality of plate-like particles are such that the plate surface is negligible on the surface of the porous substrate (fine irregularities due to the porous structure can be ignored). Macroscopic view The surface of the porous substrate is oriented perpendicularly or obliquely to the surface of the porous substrate.On the other hand, the composite portion is filled with LDH in the pores of the porous substrate to form a dense layer. It was composed.

Evaluation 3 : Elemental analysis evaluation (EDS)
Polishing was performed with a cross section polisher (CP) so that the cross-section polished surface of the functional layer (a film-like portion made of an LDH film and a composite portion made of LDH and a substrate) could be observed. With FE-SEM (ULTRA55, manufactured by Carl Zeiss), a cross-sectional image of the functional layer (a film-like portion made of an LDH film and a composite portion made of LDH and a base material) was obtained in one field of view at a magnification of 10,000 times. The elemental analysis of the LDH film on the substrate surface of this cross-sectional image and the LDH portion (point analysis) inside the substrate was performed with an EDS analyzer (NORAN System SIX, manufactured by Thermo Fisher Scientific) under the condition of an acceleration voltage of 15 kV. went. As a result, LDH constituent elements C, Mg, and Al were detected in both the LDH contained in the functional layer, that is, the LDH film on the substrate surface and the LDH portion in the substrate. That is, Mg and Al are constituent elements of the hydroxide basic layer, while C corresponds to CO ₃ ²⁻ which is an anion constituting the intermediate layer of LDH.

Examples B1 to B5
(1) Production of porous substrate An alumina porous substrate was produced in the same manner as in Example A1. The porosity of the obtained porous substrate was 40%. The average pore diameter of the porous substrate was 0.3 μm.

(2) Preparation of adhesives As shown in Table 1, the following five types of adhesives A to E were prepared.
-Adhesive A: Epoxy two-component adhesive (Henkel Japan, Hysol E30CL)
Adhesive B: Epoxy two-component adhesive (viscosity adjusted using bisphenol A type epoxy resin as the main agent and modified alicyclic polyamine as the curing agent)
-Adhesive C: Epoxy two-component adhesive (viscosity adjusted using bisphenol A type epoxy resin as the main agent and modified alicyclic polyamine as the curing agent)
-Adhesive D: Epoxy 1-pack type adhesive (Cemedine, Inc., Cemedine EP171)
Adhesive E: Epoxy two-component adhesive (Cemedine, Inc., Cemedine EP008)

The epoxy two-component adhesive includes an epoxy resin as a main agent and a polyamine type as a curing agent. The epoxy one-part adhesive includes a mixture of an epoxy resin and an epoxy curing agent. The viscosity of the main agent and the viscosity of the curing agent shown in Table 1 are values described in the product catalog of each adhesive, and the viscosity after mixing shown in Table 1 is manually mixed for 3 minutes and then allowed to stand for 5 minutes. The displayed value is 120 seconds after the sample is put into the viscometer receiver and the measurement is started. Moreover, the mixing ratio, pot life, and curing conditions shown in Table 1 adopt values described in the product catalog of each adhesive.

(3) Measurement of penetration depth The penetration depth of each adhesive with respect to the porous substrate was measured as follows.

(Examples B1 to B3 and B5)
Adhesives A, B, C, or E were weighed so as to have the mixing ratio shown in Table 1, mixed with a spatula for 1 minute, and then defoamed with a defoamer at 2000 rpm for 1 minute. As shown in FIGS. 1A and 1B, the adhesive 20 was applied to the recess 18b of the resin outer frame 18 with a spatula, and the alumina porous substrate 16 was placed thereon. The resin outer frame 18 is made of modified polyphenylene ether (ZYRON (registered trademark) EV103). The four corners of the porous substrate 16 were lightly pressed toward the resin outer frame 18 so that the adhesive 20 was attached to the end face of the alumina porous substrate 16. Then, the adhesive 20 was cured by allowing to stand under the curing conditions shown in Table 1. After the adhesive 20 was cured, the bonded portion of the obtained sample was cut out and the cross section was mechanically polished. The polished cross section was observed with an SEM, and the depth from the surface of the porous substrate 16 where the adhesive 20 soaked (that is, the soaking depth) was measured. The measured penetration depth was as shown in Table 1.

FIG. 3A shows a cross-sectional SEM image of the sample obtained in Example B1, and FIG. 3B shows a cross-sectional SEM image obtained by observing the penetration interface portion in an enlarged manner. As is clear from these figures, it can be seen that the adhesive A is sufficiently infiltrated into the alumina porous substrate over a depth of 170 μm. Moreover, the photograph which image | photographed the sample obtained in Example B1 from right above is shown in FIG. 3C. It can be seen that the square white region shown in FIG. 3C is a porous substrate, and the outer peripheral portion of the porous substrate is discolored by the penetration of the adhesive. Also from this point, it is supported that the penetration of the adhesive into the porous substrate was sufficient.

On the other hand, the cross-sectional SEM image of the sample obtained in Comparative Example B5 is shown in FIG. 4A, while the cross-sectional SEM image obtained by magnifying and observing the penetration interface portion is shown in FIG. 4B. As is clear from these figures, the penetration of the adhesive E into the alumina porous substrate was as shallow as about 50 μm in depth. Moreover, the photograph which image | photographed the sample obtained in Example B5 from right above is shown in FIG. 4C. The square white area shown in FIG. 4C is a porous substrate, but no noticeable discoloration due to penetration of the adhesive A was observed in the outer peripheral portion of the porous substrate. From this point, it can be said that the penetration of the adhesive into the porous substrate was insufficient.

(Example B4)
As shown in FIGS. 1A and 1B, the adhesive D was applied to the recess 18b of the resin outer frame 18 with a spatula, and the alumina porous substrate 16 was placed thereon. The resin outer frame 18 is made of modified polyphenylene ether (ZYRON (registered trademark) EV103). The four corners of the porous base material 16 were lightly pressed toward the resin outer frame 17 so that the adhesive 20 was attached to the end face of the alumina porous base material 16. Then, the adhesive 20 was cured by allowing to stand under the curing conditions shown in Table 1. After the adhesive 20 was cured, the bonded portion of the obtained sample was cut out and the cross section was mechanically polished. The polished cross section was observed with an SEM, and the depth from the surface of the porous substrate 16 where the adhesive 20 soaked (that is, the soaking depth) was measured. The measured penetration depth was as shown in Table 1.

(4) Evaluation of airtightness securing ratio The same as (3) above except that the composite material prepared in Example A1 (composite plate comprising an LDH separator and a porous substrate) was used instead of the alumina porous substrate. Then, the composite plate 12 was bonded to the resin outer frame 18 to obtain the separator structure 10. Ten separator structure samples were prepared for each adhesive. The following denseness determination test and He permeability measurement were performed, and the ratio of the samples in which the airtightness was confirmed in 10 samples for each adhesive was determined, and was defined as the airtightness securing ratio. The obtained airtightness securing ratio was as shown in Table 1.

<Density judgment test>
In order to confirm that the separator structure 10 does not have air permeability (ie, has airtightness), a density determination test was performed as follows. First, as shown in FIGS. 5A and 5B, an acrylic container 130 without a lid and a separator structure 10 having a shape and size that can function as a lid for the acrylic container 130 were prepared. The acrylic container 130 is formed with a gas supply port 130a for supplying gas therein. Then, the separator structure 10 was adhered to the upper end of the acrylic container 130 in a gas-tight and liquid-tight manner using a silicone adhesive 138 so as to completely close the open portion of the acrylic container 130, thereby obtaining a measurement sealed container 140. . The measurement sealed container 140 was placed in a water tank 142, and the gas supply port 130 a of the acrylic container 130 was connected to a pressure gauge 144 and a flow meter 146 so that helium gas could be supplied into the acrylic container 130. Water 143 was put into the water tank 142 and the measurement sealed container 140 was completely submerged. At this time, the inside of the measurement container 140 is sufficiently airtight and liquid-tight, and the LDH separator 14 side of the separator structure 10 is exposed to the internal space of the measurement container 140, while the porous substrate 140 The material 16 side is in contact with the water in the water tank 142. In this state, helium gas was introduced into the measurement sealed container 140 into the acrylic container 130 via the gas supply port 130a. The pressure gauge 144 and the flow meter 146 are controlled so that the differential pressure inside and outside the LDH separator 14 becomes 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). Then, it was observed whether or not helium gas bubbles were generated in the water from the separator structure 10. As a result, when generation | occurrence | production of the bubble resulting from helium gas was not observed, it determined with the separator structure 10 having a high density (that is, having airtightness) so as not to have air permeability.

<He transmission measurement>
In order to evaluate the denseness and airtightness of the separator structure 10 from the viewpoint of He permeability, a He permeation test was performed as follows. First, the He transmittance measurement system 310 shown in FIGS. 6A and 6B was constructed. The He permeability measurement system 310 is a separator in which He gas from a gas cylinder filled with He gas is supplied to a sample holder 316 via a pressure gauge 312 and a flow meter 314 (digital flow meter), and is held by the sample holder 316. The structure 10 is configured to be transmitted from one surface to the other surface and discharged.

The sample holder 316 has a structure including a gas supply port 316a, a sealed space 316b, and a gas discharge port 316c, and was assembled as follows. Support members 328a and 328b (made of PTFE) provided with gaskets made of butyl rubber as sealing members 326a and 326b at the upper and lower ends of the separator structure 10 and further provided with openings made of flanges from the outside of the sealing members 326a and 326b. ). Thus, the sealed space 316b was partitioned by the separator structure 10, the sealing member 326a, and the support member 328a. In addition, the separator structure 10 was arrange | positioned so that the LDH separator 14 side might face the gas supply port 316a. The support members 328a and 328b were firmly fastened to each other by fastening means 330 using screws so that He gas leakage did not occur from a portion other than the gas discharge port 316c. A gas supply pipe 334 was connected to the gas supply port 316 a of the sample holder 316 assembled in this way via a joint 332.

Next, He gas was supplied to the He permeability measurement system 310 via the gas supply pipe 334 and permeated through the separator structure 10 held in the sample holder 316. At this time, the gas supply pressure and the flow rate were monitored by the pressure gauge 312 and the flow meter 314. After permeation of He gas for 1 to 30 minutes, the He permeability was calculated. The calculation of the He permeability is based on the permeation amount F (cm ³ / min) of He gas per unit time, the differential pressure P (atm) applied to the LDH separator 14 during He gas permeation, and the membrane area S ( cm ² ) and calculated by the formula of F / (P × S). The permeation amount F (cm ³ / min) of He gas was directly read from the flow meter 314. Further, as the differential pressure P, the gauge pressure read from the pressure gauge 312 was used. The He gas was supplied so that the differential pressure P was in the range of 0.05 to 0.90 atm. As a result, when the He permeability of the separator structure 10 was less than 1.0 cm / min · atm, it was determined that the separator structure 10 had extremely high density and airtightness.

<Result>
As shown in Table 1, in Examples B1 to B4, the penetration depth of the adhesive reached 100 μm or more, and as a result, the airtightness securing ratio was 10 out of 10 samples, that is, 100%. On the other hand, in Example B5 which is a comparative example, the penetration depth of the adhesive did not reach 100 μm, and as a result, the airtightness securing ratio was 7 out of 10 samples, that is, 70%.

(6) Evaluation of Adhesiveness As shown in FIG. 7, the adhesive rod 20 was applied to both surfaces of the alumina porous substrate 16 to adhere the resin rod 102. A tensile strength test was performed using the sample 100 thus obtained. As a result, in any of Examples B1 to B5, peeling at the interface between the porous substrate 16 and the adhesive 20 does not occur, and the other interface (specifically, the interface between the resin rod 102 and the adhesive 20). The peeling occurred. In addition, the same result was obtained even if it was the sample after being immersed in alkaline aqueous solution. From these results, it can be seen that high adhesive strength can be obtained by the penetration of the adhesive.

Claims (11)

1. A separator structure for a zinc secondary battery,
   A composite plate comprising a layered double hydroxide (LDH) separator and a porous substrate provided on one side of the LDH separator;
   A resin outer frame having an opening into which the composite plate is fitted;
   With
   The resin outer frame has a recess that locks the porous substrate side of the composite plate along its inner periphery, and the recess and the composite plate are sealed and bonded with an adhesive,
   The porous substrate has a thickness of 100 μm or more, and a portion of the porous substrate that faces the recess is infiltrated with the adhesive over a depth of 100 μm or more from the surface of the porous substrate. The separator structure.
2. 2. The separator structure according to claim 1, wherein the thickness of the porous base material is 100 to 600 μm, and the depth of the porous member soaked with the adhesive is 100 to 600 μm.
3. The separator structure according to claim 1 or 2, wherein the adhesive contains a resin having alkali resistance.
4. The adhesive according to any one of claims 1 to 3, wherein the adhesive is at least one selected from the group consisting of an epoxy resin adhesive, a natural resin adhesive, a modified olefin resin adhesive, and a modified silicone resin adhesive. The separator structure according to claim 1.
5. The separator structure according to any one of claims 1 to 4, wherein the resin outer frame is composed of at least one selected from the group consisting of an ABS resin, a modified polyphenylene ether, and a polypropylene resin. .
6. The separator structure according to any one of claims 1 to 5, wherein the porous substrate is composed of at least one selected from the group consisting of a ceramic material, a metal material, and a polymer material.
7. The separator structure according to any one of claims 1 to 6, wherein the LDH separator has gas impermeability and / or water impermeability.
8. The separator structure according to any one of claims 1 to 7, wherein the separator structure as a whole is gas-impermeable and / or water-impermeable.
9. The LDH separator has an LDH film composed of an aggregate of a plurality of LDH plate-like particles, and the plate surfaces of the plurality of LDH plate-like particles are perpendicular or oblique to the surface of the porous substrate. The separator structure according to any one of claims 1 to 8, wherein the separator structure is oriented in an intersecting direction.
10. A positive electrode comprising nickel hydroxide and / or nickel oxyhydroxide,
    A negative electrode comprising zinc, a zinc alloy and / or zinc oxide;
    An electrolyte containing an alkali metal hydroxide aqueous solution;
    The separator structure according to any one of claims 1 to 9, wherein the positive electrode and the negative electrode are separated so as to be able to conduct hydroxide ions.
    A nickel-zinc secondary battery comprising:
11. The air electrode,
    A negative electrode comprising zinc, a zinc alloy and / or zinc oxide;
    An electrolyte containing an alkali metal hydroxide aqueous solution;
    The separator structure according to any one of claims 1 to 9, wherein the air electrode and the negative electrode are separated so as to conduct hydroxide ions.
    A zinc-air secondary battery comprising:

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