JP6586221B2 - Method for selecting an adhesive suitable for manufacturing an alkaline secondary battery, and an alkaline secondary battery - Google Patents

Description

  The present invention relates to a method for selecting an adhesive suitable for manufacturing an alkaline secondary battery, and an alkaline secondary battery.

  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.

International Publication No. 2013/118561 International Publication No. 2013/073292 International Publication No. 2016/006330

  The present applicant has succeeded in the development of a ceramic separator (inorganic solid electrolyte separator) that has hydroxide ion conductivity but is highly densified to such an extent that it does not have water permeability and air permeability. Moreover, the present inventors have succeeded in forming such a ceramic separator on a porous substrate (for example, an alumina porous substrate), and the applicant has already proposed a nickel-zinc battery equipped with the ceramic separator (for example, Patent Document 3 (see International Publication No. 2016/006330). 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 this case, it is desirable to securely bond the ceramic separator to the battery container with an adhesive or the like. However, the alkaline secondary battery to which the hydroxide ion conductive ceramic separator is applied includes an alkaline electrolyte such as a potassium hydroxide aqueous solution that is a strong alkali, and the battery container is preferably made of an alkali-resistant resin. Will be. For this reason, the adhesive used for the said use places the high request | requirement of being excellent also in alkali resistance as well as ensuring the adhesiveness to both ceramics and resin. That is, it is required that the bonding interface bonded with the adhesive and the adhesive itself do not allow the alkaline electrolyte to permeate over a long period of time. In particular, the alkaline secondary battery is assumed to be used for a long time by repeating charging and discharging, and it is desired that the alkali resistance of the adhesive is ensured for a long time.

  The present inventors have recently solidified the adhesive to be evaluated, and performed treatment and concentration measurement according to a predetermined procedure, whereby an alkaline secondary battery (especially an alkaline secondary battery using a hydroxide ion conductive ceramic separator) is obtained. We obtained knowledge that an adhesive with excellent alkali resistance suitable for the manufacture of secondary batteries can be selected with high accuracy.

  Therefore, an object of the present invention is to select with high accuracy an adhesive having excellent alkali resistance suitable for the production of an alkaline secondary battery (particularly an alkaline secondary battery using a hydroxide ion conductive ceramic separator). is there.

According to one aspect of the present invention, there is provided a method for selecting an adhesive suitable for manufacturing an alkaline secondary battery,
Solidifying the adhesive to be evaluated into a plate-like adhesive solidified body having a thickness of 100 μm or more;
Dipping the adhesive solidified body in an aqueous 8.5 to 9.5 mol / L potassium hydroxide solution at 85 to 95 ° C. for 480 to 530 hours, and taking out the adhesive solidified body;
Washing the taken-out adhesive solidified body with ion-exchanged water until the pH of the washing liquid after washing becomes less than 8.
Drying the adhesive solidified body after washing;
The maximum potassium concentration at a depth of 50 μm from the surface of the adhesive solidified body after the drying was measured, and the adhesive that resulted in the adhesive solidified body having the maximum potassium concentration of 0.01 to 3.00 at% was obtained. Selecting an adhesive suitable for the production of the alkaline secondary battery;
A method is provided comprising:

According to another aspect of the present invention, an alkaline secondary battery using a hydroxide ion conductive ceramic separator, wherein the alkaline secondary battery includes a positive electrode, a negative electrode, an alkaline electrolyte, and the positive electrode. And a separator structure that separates the negative electrode, and a resin container that contains at least the negative electrode and the alkaline electrolyte,
The separator structure includes a ceramic separator made of an inorganic solid electrolyte body having hydroxide ion conductivity, or includes the ceramic separator and a resin frame and / or a resin film surrounding an outer periphery of the ceramic separator. ,
The separator structure is bonded to the resin container via an adhesive and / or the ceramic separator is bonded to the resin frame and / or the resin film via an adhesive;
When the adhesive is evaluated by the method according to the above aspect, an alkaline secondary battery is provided that is selected as an adhesive suitable for manufacturing the alkaline secondary battery.

It is a schematic cross section which shows an example of the secondary battery by which the separator structure provided with the resin-made frames and the resin film was integrated in the flexible bag which is a resin-made container which has flexibility. It is the image which image | photographed an example of the resin film provided with the resin-made frames. 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 cross-sectional SEM image of an adhesive solidified body (adhesive A) produced in Example 1. FIG. 4 is a graph showing potassium concentration (atomic%) in an adhesive at a depth of 50 μm from the surface of the adhesive solidified body (adhesive A) produced in Example 1. FIG. 2 is a schematic cross-sectional view of an evaluation sample produced in Example 1. FIG. 2 is a graph showing potassium (K) concentration at each distance from the adhesive surface, measured for adhesive D in Example 1. FIG. 4 is a graph showing the silicon (Si) concentration at each distance from the adhesive surface, measured for adhesive D in Example 1. FIG. 4 is a SEM image of the surface of an alumina porous substrate produced in Example 2. 3 is an XRD profile obtained for the crystal phase of the sample in Example 2. 6 is a SEM image showing the surface microstructure of the film sample observed in Example 2. 4 is a SEM image of a polished cross-sectional microstructure of a composite material sample observed in Example 2. FIG. 6 is an exploded perspective view of a denseness discrimination measurement system used in Example 2. FIG. 6 is a schematic cross-sectional view of a denseness discrimination measurement system used in Example 2. FIG. 6 is an exploded perspective view of a measurement sealed container used in the denseness determination test II of Example 2. FIG. 4 is a schematic cross-sectional view of a measurement system used in a denseness determination test II of Example 2. FIG. It is a conceptual diagram which shows an example of a He transmittance | permeability measurement system. It is a schematic cross section of the sample holder used in the measurement system shown in FIG. 17A and its peripheral configuration. It is a conceptual diagram which shows an example of a Zn permeation | transmission ratio measuring apparatus. It is a schematic cross section of the sample holder used for the measuring apparatus shown in FIG. 18A. 6 is a graph showing the relationship between the He transmittance measured in Example 5 and the Zn transmission ratio.

Adhesive Selection Method The method of the present invention is an adhesive selection method suitable for the production of alkaline secondary batteries. In the present invention, the alkaline secondary battery preferably uses a hydroxide ion conductive ceramic separator, and such a battery can be said to be a battery in which a charge / discharge reaction involving hydroxide ions is performed. . Alkaline secondary batteries include nickel-zinc secondary batteries, silver-zinc oxide secondary batteries, manganese-zinc oxide secondary batteries, zinc-air secondary batteries, and other various alkaline zinc secondary batteries, lithium-air secondary batteries, etc. Various secondary batteries to which a hydroxide ion conductive ceramic separator can be applied can be used.

  In the method of the present invention, first, the adhesive to be evaluated is solidified in the form of a plate-like adhesive solidified body having a thickness of 100 μm or more. Next, the adhesive solidified body is immersed in an aqueous 8.5 to 9.5 mol / L potassium hydroxide solution at 85 to 95 ° C. for 480 to 530 hours, and the adhesive solidified body is taken out. The taken-out adhesive solidified body is washed with ion exchange water until the pH of the washing liquid after washing becomes less than 8. The adhesive solidified body after washing is dried. Finally, the maximum potassium concentration at a depth of 50 μm from the surface of the adhesive solidified body after drying was measured, and the adhesive that resulted in the adhesive solidified body having a maximum potassium concentration of 0.01 to 3.00 at% was obtained. And an adhesive suitable for the production of alkaline secondary batteries. Production of an alkaline secondary battery (especially an alkaline secondary battery using a hydroxide ion conductive ceramic separator) by solidifying the adhesive to be evaluated in this manner and performing processing and concentration measurement in a predetermined procedure Adhesives with excellent alkali resistance can be selected with high accuracy.

  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. And in order to exhibit this effect to the maximum, it is desired to reliably partition the resin container into the positive electrode side and the negative electrode side with a separator structure including a hydroxide ion conductive ceramic separator. Therefore, it is desirable to securely bond the separator structure to a resin member such as a resin container with an adhesive or the like. Further, when the separator structure includes a resin frame and / or resin film surrounding the outer periphery of the ceramic separator, the ceramic separator (or ceramic separator with a porous substrate) is securely attached to the resin frame and / or resin film. It is desirable to bond with an adhesive or the like. However, the alkaline secondary battery contains an alkaline electrolyte, and the battery container is preferably made of an alkali-resistant resin. For this reason, the adhesive used for the said use places the high request | requirement of being excellent also in alkali resistance as well as ensuring the adhesiveness to both ceramics and resin. That is, it is required that the bonding interface bonded with the adhesive and the adhesive itself do not allow the alkaline electrolyte to permeate over a long period of time. In particular, the alkaline secondary battery is assumed to be used for a long time by repeating charging and discharging, and it is desired that the alkali resistance of the adhesive is ensured for a long time. In this respect, according to the method of the present invention, the long-term alkali resistance against a potassium hydroxide aqueous solution, which is a typical alkaline electrolyte, can be evaluated by an objective numerical value, so that the above high requirements are satisfied. Adhesive can be selected with high accuracy.

  Hereafter, each process of the method of this invention is demonstrated.

(1) Solidification of adhesive First, the adhesive to be evaluated is solidified in the form of a plate-like adhesive solidified body having a thickness of 100 μm or more. The adhesive to be evaluated is not particularly limited, but is preferably an adhesive suitable for bonding a hydroxide ion conductive ceramic separator and a resin. Examples of such adhesives include epoxy resin adhesives, natural resin adhesives, modified olefin resin adhesives, modified silicone resin adhesives, and any combination thereof. In particular, the adhesive is preferably an epoxy resin adhesive, and more preferably the Si content in the epoxy resin adhesive is 0 to 1.7% by weight. Details of the adhesive will be described later. In any case, these adhesives may be commercially available adhesives, and solidification of the adhesive is preferably performed based on information such as instruction manuals attached to the adhesive to be used. The thickness of the plate-like adhesive solidified body is not particularly limited as long as it is 100 μm or more, but is, for example, 1 mm. Further, the size of the adhesive solidified body is not particularly limited, but for example, a size of 20 mm × 20 mm × 1 mm is sufficient.

(2) Immersion in aqueous potassium hydroxide solution The obtained adhesive solidified body was immersed in an aqueous 8.5 to 9.5 mol / L potassium hydroxide aqueous solution at 85 to 95 ° C. for 480 to 530 hours to form an adhesive solidified body. Take out. The concentration of the potassium hydroxide aqueous solution is 8.5 to 9.5 mol / L, more preferably 8.8 to 9.2 mol / L, and most preferably 9 mol / L, for example 9.0 mol / L. The temperature of the potassium hydroxide aqueous solution is 85 to 95 ° C, preferably 88 to 92 ° C, and most preferably 90 ° C. The immersion time of the adhesive solidified body at the temperature within the above range is 480 to 530 hours, more preferably 490 to 520 hours, further preferably 495 to 510 hours, particularly preferably 500 to 505 hours, and most preferably 504. It's time. The aqueous potassium hydroxide solution in which the adhesive solidified body is immersed is preferably stored in a low-temperature dryer set to a temperature within the above range. The amount of the potassium hydroxide aqueous solution may be appropriately determined according to the size of the adhesive solidified body. For example, in the case of the above-mentioned adhesive solidified body having a size of 20 mm × 20 mm × 1 mm, it is preferably 50 cc to 60 cc.

(3) Washing of the adhesive solidified body The above-mentioned taken out adhesive solidified body is washed with ion-exchanged water until the pH of the washing liquid after washing becomes less than 8. That is, when the pH of the cleaning liquid after cleaning exceeds 8, the cleaning may be repeated until the pH of the cleaning liquid after cleaning becomes less than 8.

(4) Drying of the adhesive solidified body The adhesive solidified body after the washing is dried. This drying is preferably performed at room temperature in an air atmosphere. The drying time is not particularly limited as long as it is longer than the time required for the adhesive solidified body to dry (that is, the attached ion exchange water disappears), and is preferably 12 hours or longer.

(5) Measurement of maximum potassium concentration and selection of adhesive The maximum potassium concentration at a depth of 50 µm from the surface of the adhesive solidified body after drying is measured. The measurement of the maximum potassium concentration is preferably performed by the following procedure. First, the adhesive solidified body after drying is embedded in an epoxy resin to produce a measurement sample. This sample is cut with a leuter or the like, and the cut surface is polished. This polishing is preferably performed using abrasive paper, and the preferred count of the abrasive paper is # 4000. The polished sample is milled with a commercially available ion milling apparatus. This milling process may be performed, for example, at an acceleration voltage of 5 kV for 3 hours. The milled cross section is observed and analyzed by SEM (scanning electron microscope) and EDS (energy dispersive X-ray spectrometer). SEM observation may be performed at a magnification of 200 times, for example. In addition, the EDS analysis specifies the part where the contrast between the adhesive and the epoxy resin is changed in the SEM image as the adhesive surface, and conducts semi-quantitative analysis from the adhesive surface of the sample to a depth of 50 μm every 10 μm. It may be performed by. The maximum value of the potassium concentration thus measured may be adopted as the maximum potassium concentration.

  And the adhesive which brought about the adhesive solidified body whose maximum potassium concentration measured as mentioned above is 0.01-3.00 at% is selected as an adhesive suitable for manufacture of an alkaline secondary battery. The maximum potassium concentration may be 0.01 to 3.00 at%, more preferably 0.01 to 2.00 at%, further preferably 0.01 to 1.50 at%, particularly preferably 0.01 to 0. .50 at%.

(6) Manufacture of alkaline secondary battery The adhesive selected as described above is suitable for the manufacture of alkaline secondary batteries (especially alkaline secondary batteries using hydroxide ion conductive ceramic separators). It is expected with high accuracy that the adhesive is excellent in alkalinity. Therefore, it is preferable to provide or use the selected adhesive for the production of alkaline secondary batteries. A preferred embodiment of the alkaline secondary battery will be described below.

Alkaline Secondary Battery As described above, the method for selecting an adhesive according to the present invention is suitable for the production of an alkaline secondary battery, and particularly suitable for the production of an alkaline secondary battery using a hydroxide ion conductive ceramic separator. . Such alkaline secondary batteries include nickel zinc secondary batteries, silver zinc oxide secondary batteries, manganese zinc secondary batteries, zinc air secondary batteries, and various other alkaline zinc secondary batteries, and lithium air secondary batteries. Various secondary batteries to which a hydroxide ion conductive ceramic separator can be applied, such as a battery, can be used. 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 a nickel-zinc secondary battery and a zinc-air secondary battery, but the secondary battery of the present invention is limited to a nickel-zinc secondary battery and a zinc-air secondary battery. The above-mentioned various alkaline secondary batteries that can employ a hydroxide ion conductive ceramic separator are conceptually included.

  An alkaline secondary battery according to a preferred embodiment of the present invention includes a positive electrode, a negative electrode, an alkaline electrolyte, a separator structure, and a resin container. The separator structure is a member that separates the positive electrode and the negative electrode, and includes a ceramic separator made of an inorganic solid electrolyte body having hydroxide ion conductivity. The separator structure may be composed of a ceramic separator (or a ceramic separator with a porous substrate) itself, or further includes a resin frame and / or a resin film surrounding the outer periphery of the ceramic separator. There may be. What is necessary is just to select a positive electrode suitably according to the kind of secondary battery. For example, in the case of a nickel zinc battery, the positive electrode includes nickel hydroxide and / or nickel oxyhydroxide. In the case of a zinc-air battery, the positive electrode is 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. If desired, a porous substrate (preferably a ceramic porous substrate) may be provided on one or both surfaces of the ceramic separator. In this case, the porous substrate constitutes a part of the separator structure. The resin container contains at least the negative electrode and the alkaline electrolyte. In a typical alkaline secondary battery such as a nickel zinc battery, the resin container can also contain a positive electrode and a positive electrode electrolyte. However, in the case where the positive electrode is configured as an air electrode, such as a metal-air secondary battery such as a zinc-air secondary battery, the air electrode (positive electrode) does not need to be completely accommodated in a resin container. It may be attached in such a manner as to close the opening of the resin container (for example, in the shape of a lid). Note that the positive electrode and the alkaline electrolyte need not necessarily be separated from each other, 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. If desired, a positive electrode current collector may be provided in contact with the positive electrode. If desired, a negative electrode current collector may be provided in contact with the negative electrode.

  In the secondary battery of the present invention, the separator structure is bonded to the resin container via the adhesive, and / or the ceramic separator is attached to the resin frame and / or the resin film via the adhesive. As the adhesive, an adhesive selected as an adhesive suitable for the manufacture of an alkaline secondary battery when evaluated by the method of the present invention is used.

  The adhesive may be applied to a portion (mainly the outer peripheral portion of these members) to be bonded to a resin member such as a resin container of the separator structure, and should be bonded to a resin member such as a resin container. It is preferable that the adhesive is applied over the entire outer peripheral portion. In the case of a ceramic separator with a porous substrate, an adhesive is applied to a porous substrate (preferably a ceramic porous substrate), or an adhesive is applied only to a porous substrate, Adhesion to the container is preferable in that a large adhesion area can be secured and adhesion can be performed more reliably. When the separator structure includes a resin frame and / or resin film surrounding the ceramic separator, an adhesive is applied to the resin frame and / or resin film instead of the ceramic separator and bonded to the resin container. Can be made. It is also possible to apply an adhesive to the outer periphery of a ceramic separator (or a ceramic separator with a porous substrate) and adhere a resin frame and / or resin film to the outer periphery. In any joint location, sufficient liquid-tightness can be ensured by sealing the members to be joined with an adhesive.

  The adhesive used in the present invention is preferably at least one selected from the group consisting of epoxy resin adhesives, natural resin adhesives, modified olefin resin adhesives, and modified silicone resin adhesives. These adhesives are all excellent in adhesion to both ceramics and resin. Among these, 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 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.

In particular, the content of Si in the epoxy resin adhesive is preferably 0 to 1.7% by weight (including 0), more preferably 0 to 1.5% by weight, and still more preferably 0 to 1.0% by weight. It is. Thus, by reducing the content of Si in the epoxy resin adhesive, the alkali resistance is remarkably improved. The mechanism is not clear, but if Si is contained in the epoxy resin adhesive as SiO ₂ or the like, SiO ₂ is eluted into a strong alkali such as an aqueous potassium hydroxide solution and the adhesive deteriorates. It is thought that.

  The epoxy resin-based adhesive described above is a thermosetting adhesive, but a natural resin-based adhesive and / or a modified olefin resin-based adhesive can also be used as the thermoplastic resin-based 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 further 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.

  A separator structure including a ceramic separator (hereinafter also simply referred to as “separator”) is provided so as to separate the positive electrode and the negative electrode. In a typical alkaline secondary battery such as a nickel-zinc battery, the separator partitions a positive electrode chamber containing a positive electrode and a positive electrode electrolyte and a negative electrode chamber containing a negative electrode and a negative electrode electrolyte in a resin container. Provided. Alternatively, in the case of a metal-air secondary battery such as a zinc-air secondary battery, a separator is provided so as to close the opening of the resin container so as to be in contact with the electrolyte and form a resin container and a negative electrode side sealed space. May be. The separator preferably has hydroxide ion conductivity but does not have water permeability and air permeability. That is, the fact that the separator does not have water permeability and air permeability means that the separator has a high degree of denseness that does not allow water and gas to pass through. It means not a porous material. For this reason, in the case of a zinc secondary battery, 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. 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 has become. In any case, since the ceramic separator has hydroxide ion conductivity, the efficiency of hydroxide ions required between the positive electrode side (for example, alkaline electrolyte or air electrode) and the negative electrode side (for example, alkaline electrolyte). Charge and discharge reactions at the positive electrode and the negative electrode can be realized.

The ceramic separator 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. A separator having a He permeability of 10 cm / min · atm or less can very effectively suppress Zn permeation in the electrolytic solution. For example, as shown in FIG. 19 described later, when the He permeability is 10 cm / min · atm or less, the Zn permeation rate per unit area when evaluated under water contact is significantly reduced. In that sense, it can be said that the upper limit value of the He permeability of 10 cm / min · atm has a critical significance regarding the Zn permeation suppressing effect in the hydroxide ion conductive separator. Thus, it is thought that the separator of this embodiment can suppress the growth of zinc dendrite effectively when used in a nickel zinc secondary battery because Zn permeation is remarkably suppressed. The He permeability is obtained by supplying He gas to one side of the separator and allowing the He gas to pass through the separator, and calculating the He permeability and evaluating the denseness of the hydroxide ion conductive separator. Measured. The He permeability is calculated by the following formula: F / (P × S) using the permeation amount F of He gas per unit time, the differential pressure P applied to the separator during He gas permeation, and the membrane area S through which He gas permeates. calculate. 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 compactness such that Zn that is 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. In this respect, since hydrogen gas is composed of H ₂ molecules, a single He atom is smaller as a gas constituent unit. In the first place, H ₂ gas is dangerous because it is a combustible gas. 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 or not the 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 Example 3 described later.

The ceramic separator preferably has a Zn transmission rate per unit area of 10 m ⁻² · h ⁻¹ or less, more preferably 5.0 m ⁻² · h ⁻¹ or less, when evaluated under water contact. It is 4.0 m ⁻² · h ⁻¹ or less, more preferably 3.0 m ⁻² · h ⁻¹ or less, more preferably 1.0 m ⁻² · h ⁻¹ or less. Such a low Zn permeation ratio means that the permeation of Zn (typically permeation of zinc ions or zincate ions) in the electrolytic solution can be extremely effectively suppressed. For this reason, it is thought in principle that the growth of zinc dendrite can be effectively suppressed when used in a nickel zinc secondary battery. The Zn transmission rate is determined through a step of allowing Zn to pass through the separator for a predetermined time and a step of calculating the Zn transmission rate. For the permeation of Zn into the separator, the first aqueous solution containing Zn is brought into contact with one surface of the hydroxide ion conducting separator, and the second aqueous solution or water not containing Zn is introduced into the other surface of the separator. This is done by contacting them. In addition, the Zn permeation ratio is the Zn concentration C ₁ of the first aqueous solution before the start of Zn permeation, the volume V ₁ of the first aqueous solution before the start of Zn permeation, the second aqueous solution after the completion of Zn permeation, or the Zn of water. (C ₂ × V ₂ ) / (C ₁ ) using the concentration C ₂ , the second aqueous solution or water volume V ₂ after the completion of Zn permeation, the Zn permeation time t, and the film area S through which Zn permeates. × is calculated by the equation of _{V 1} × t × S). The units of the parameters C ₁ , C ₂ , V ₁ , V ₂ , t and S are particularly limited as long as the units of the concentrations C ₁ and C ₂ are aligned and the units of the liquid amounts V ₁ and V ₂ are aligned. However, it is preferable that the unit of Zn transmission time t is h and the unit of film area S is m ² . The Zn concentration C ₁ of the first aqueous solution before Zn permeation is preferably in the range of 0.001 to ₁ mol / L, more preferably 0.01 to 1 mol / L, and still more preferably 0.05 to 0. 8 mol / L, particularly preferably 0.2 to 0.5 mol / L, most preferably 0.35 to 0.45 mol / L. The Zn permeation time is preferably 1 to 720 hours, more preferably 1 to 168 hours, still more preferably 6 to 72 hours, and particularly preferably 12 to 24 hours. Thus, by evaluating Zn permeability using a Zn-containing aqueous solution and a Zn-free solution, it is possible to evaluate the presence or absence of denseness at an extremely high level. It is possible to reliably and highly accurately evaluate high-density such that Zn that causes growth is not transmitted as much as possible (only a very small amount is transmitted). Then, by adopting an index called Zn transmission rate defined by the above-described formula, objective evaluation regarding denseness can be easily performed regardless of differences in various sample sizes and measurement conditions. This Zn transmission rate can be an effective index for judging the difficulty of precipitation of zinc dendrite. This is because, when a hydroxide ion conductive separator is used as a separator in a zinc secondary battery, even if Zn is contained in the negative electrode electrolyte on one side (zinc negative electrode side) of the separator, This is because, in principle, it is considered that the growth of zinc dendrite in the positive electrode electrolyte is effectively suppressed unless Zn permeates the positive electrode electrolyte (which originally does not contain Zn). Thus, according to this aspect, it is possible to reliably and accurately evaluate whether or not the separator has a sufficiently high density suitable for a zinc secondary battery separator. The measurement of the Zn transmission ratio can be preferably performed according to the procedure shown in Example 3 described later.

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

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

  A porous substrate may be provided on one side or both sides of the ceramic separator. 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. Also, a dense film or a dense layer of an inorganic solid electrolyte (preferably LDH) can be formed on or in the porous substrate. When providing a porous substrate on one side of the separator, a method of preparing a porous substrate and depositing an inorganic solid electrolyte on the porous substrate can be considered (this method will be described later). On the other hand, when providing a porous base material on both surfaces of a separator, it can be considered that densification is performed by sandwiching a raw material powder of an inorganic solid electrolyte between two porous base materials. For example, the porous substrate may be provided over the entire surface of one side of the separator, or may be provided only on a part of one side of the separator (for example, a region involved in the charge / discharge reaction). For example, when an inorganic solid electrolyte body is formed in a film or layer on or in a porous substrate, the porous substrate is provided over the entire surface of one side of the separator derived from the manufacturing method. Is typical. On the other hand, when the inorganic solid electrolyte body is formed in a self-supporting plate shape (which does not require a base material), a porous base material is retrofitted only on a part of one side of the separator (for example, a region involved in the charge / discharge reaction). Alternatively, a porous substrate may be retrofitted over the entire surface of one side.

  The separator structure may include a resin frame and / or a resin film surrounding the outer periphery of the ceramic separator. It is preferable that the separator structure does not have water permeability or air permeability as a whole. The separator structure includes a separator having hydroxide ion conductivity but not water permeability, thereby permitting hydroxide ion conduction but not allowing liquid communication between the positive electrode chamber and the negative electrode chamber. Configured as follows. The resin constituting the resin frame is preferably a resin having resistance to an alkali metal hydroxide such as potassium hydroxide, more preferably a polyolefin resin (for example, a polypropylene resin), an ABS resin, a modified polyphenylene ether, or their It is a combination, and more preferably at least one selected from the group consisting of ABS resin, modified polyphenylene ether, and polypropylene resin. The resin film preferably has resistance to alkali metal hydroxides such as potassium hydroxide and can be joined by heat fusion, for example, PP (polypropylene) film, PET (polyethylene terephthalate). Examples thereof include a film and a PVC (polyvinyl chloride) film. As a flexible film including a resin film, a commercially available laminate film can be used. As a preferable laminate film, a base film (for example, a PET film or a PP film) and a thermoplastic resin layer having two or more layers are provided. A heat laminate film is mentioned. A preferable thickness of the flexible film (for example, a laminate film) is 20 to 500 μm, more preferably 30 to 300 μm, and still more preferably 50 to 150 μm. Bonding or sealing by thermal fusion may be performed using a commercially available heat sealing machine or the like.

  The alkaline electrolyte may be any alkaline electrolyte that can be used in a secondary battery, but is preferably an aqueous solution of an alkali metal hydroxide. 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 zinc and / or zinc oxide. 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.

  The resin container contains at least the negative electrode and the alkaline electrolyte. In any case, the resin container preferably has a structure having liquid tightness and air tightness. 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 (for example, a polypropylene resin), an ABS resin, a modified polyphenylene ether, or their It is a combination, and more preferably at least one selected from the group consisting of ABS resin, modified polyphenylene ether, and polypropylene resin. The separator structure is fixed to the resin container using the adhesive described above.

  The resin container is not limited to the hard resin container as described above, and may be a flexible resin container (for example, a flexible bag) or a combination thereof. FIG. 1 shows an example of an alkaline secondary battery (typically a nickel-zinc secondary battery) provided with a hard resin container and a flexible bag housed therein. The alkaline secondary battery 10 shown in FIG. 1 accommodates a flexible bag 22 composed of a pair of resin films 22a and 22b as a flexible film in a hard resin container 23 which is a sealed container. Has been. In the flexible bag 22, the positive electrode 12, the positive electrode electrolyte 14, the negative electrode 16, the negative electrode electrolyte 18, and the separator structure 30 are accommodated, and the positive electrode 12 and the positive electrode electrolyte 14 are interposed via the separator structure 30. The anode 16 and the anode electrolyte 18 are isolated. A positive electrode terminal 13 extending from the positive electrode 12 and a negative electrode terminal 17 extending from the negative electrode 16 are extended outside the hard resin container 23.

  The resin films 22a and 22b constituting the flexible bag body 22 preferably have resistance to alkali metal hydroxides such as potassium hydroxide and can be joined by thermal fusion. For example, Examples include PP (polypropylene) film, PET (polyethylene terephthalate) film, PVC (polyvinyl chloride) film, and the like. As a flexible film including a resin film, a commercially available laminate film can be used. As a preferable laminate film, a base film (for example, a PET film or a PP film) and a thermoplastic resin layer having two or more layers are provided. A heat laminate film is mentioned. A preferable thickness of the flexible film (for example, a laminate film) is 20 to 500 μm, more preferably 30 to 300 μm, and still more preferably 50 to 150 μm. As shown in FIG. 1, the flexible bag 22 is composed of a pair of resin films 22a and 22b, and at least a portion other than the upper end of the outer peripheral edge of the pair of resin films 22a and 22b is sealed by thermal fusion. It is preferable that By sealing at least the portion other than the upper end of the outer peripheral edge, the positive electrode electrolyte 14 and the negative electrode electrolyte 18 can be reliably held in the flexible bag 22 without liquid leakage. As shown in FIG. 1, when the flexible bag body 22 is accommodated in another hard resin container 23, the flexible bag body 22 may be open at the top. Alternatively, the upper end portion of the flexible bag body 22 may be sealed by heat-sealing to ensure liquid-tightness of the flexible bag body 22 as a whole. What is necessary is just to seal the upper end part of the flexible bag body 22 by heat sealing | fusion after inject | pouring a liquid. Bonding or sealing by thermal fusion may be performed using a commercially available heat sealing machine or the like.

  As shown in FIG. 1, the preferred separator structure 30 includes both a resin frame 32 and a resin film 34, and the outer periphery of the ceramic separator 20 is surrounded by the resin frame 32, and the resin frame 32 has a resin. The film 34 is joined so as to surround the outer periphery of the ceramic separator 20. In this case, it is preferable that the ceramic separator 20 is bonded to the outer periphery thereof with the resin frame 32 and the adhesive 36, and it is sufficient that the gap between the ceramic separator 20 and the resin frame 32 is sealed with the adhesive 36. Liquid tightness can be secured. The preferred materials for the resin frame 32 and the resin film 34 are as described above. The resin frame 32 and the resin film 34 are preferably bonded by thermal fusion, and a photograph of the product thus produced is shown in FIG. As shown in FIG. 2, the resin frame 32 and the resin film 34 to be bonded to each other have an opening, and a ceramic separator 20 (or a ceramic separator with a porous substrate) is joined to the opening. It will be. As described above, the flexible bag 22 is composed of a pair of resin films 22a and 22b, and at least a portion other than the upper end portion of the outer peripheral edge of the pair of resin films 22a and 22b is sealed by heat sealing. preferable. In this case, at least a portion other than the upper end of the outer peripheral edge of the resin film 34 constituting the separator structure 30 is heat-sealed together with the pair of resin films 22a and 22b in a state of being sandwiched between the pair of resin films 22a and 22b. It is preferable that they are joined together. More preferably, it is joined by heat fusion in a state of being sandwiched between the pair of resin films 22a and 222b over substantially the entire region including or not including the upper end portion of the outer peripheral edge of the resin film 34 constituting the separator structure 30.

LDH separator with porous substrate As described above, a separator with a porous substrate that is preferably used in the zinc secondary battery of the present invention includes a separator composed of an inorganic solid electrolyte having hydroxide ion conductivity, and at least a separator. And a porous substrate provided on one surface. The inorganic solid electrolyte body is in the form of a film or layer that is so dense that it does not have water permeability. A particularly preferred separator with a porous substrate comprises a porous substrate and a separator layer formed on and / or in the porous substrate, and the separator layer is layered as described above. It contains double hydroxide (LDH). The separator layer preferably does not have water permeability and air permeability. That is, the porous material can have water permeability and air permeability due to the presence of pores, but the separator layer is preferably densified with LDH to such an extent that it does not have water permeability and air permeability. The separator layer is preferably formed on a porous substrate. For example, as shown in FIG. 3, the separator layer 20 is preferably formed on the porous substrate 28 as an LDH dense film. In this case, needless to say, LDH may be formed on the surface of the porous substrate 28 and in the pores in the vicinity thereof as shown in FIG. 3 due to the nature of the porous substrate 28. Alternatively, as shown in FIG. 4, LDH is densely formed in the porous substrate 28 (for example, in the surface of the porous substrate 28 and in the pores in the vicinity thereof), whereby at least one of the porous substrates 28 is formed. The part may constitute separator layer 20 '. In this regard, the embodiment shown in FIG. 4 has a configuration in which the membrane equivalent portion of the separator layer 20 of the embodiment shown in FIG. 3 is removed, but is not limited to this, and is parallel to the surface of the porous substrate 28. 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, 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 an LDH-containing separator layer having excellent denseness. Preferable examples of the metal material include aluminum and zinc. Preferable examples of the polymer material include polystyrene, polyether sulfone, polypropylene, epoxy resin, polyphenylene sulfide, hydrofluorinated fluororesin (tetrafluorinated resin: PTFE, etc.), 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 20 is formed on the porous substrate 28 as shown in FIG. 3, the separator layer 20 is in the form of an LDH dense film, which is typically from LDH. Become. As shown in FIG. 4, when the separator layer 20 ′ is formed in the porous substrate 28, the surface of the porous substrate 28 (typically the surface of the porous substrate 28 and the vicinity thereof). Since the LDH is densely formed in the pores), the separator layer 20 ′ is typically composed of at least a part of the porous substrate 28 and LDH. The separator layer 20 ′ shown in FIG. 4 can be obtained by removing a portion corresponding to the film in the separator layer 20 shown in FIG. 3 by a known method such as polishing or cutting.

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

  The layered double hydroxide is composed of an aggregate of a plurality of plate-like particles (that is, LDH plate-like particles), and the plurality of plate-like particles have their plate surfaces perpendicular to the surface of the porous substrate (substrate surface). It is preferable that they are oriented in such a direction as to cross each other diagonally. As shown in FIG. 3, this embodiment is a particularly preferable and feasible embodiment when the separator layer 20 is formed as an LDH dense film on the porous substrate 28, but as shown in FIG. 4, LDH is densely formed in the porous substrate 28 (typically in the surface of the porous substrate 28 and in the pores in the vicinity thereof), whereby at least a part of the porous substrate 28 forms the separator layer 20 ′. This can be realized even in the case of configuration.

  That is, the LDH crystal is known to have the form of a plate-like particle having a layered structure as shown in FIG. 5, but the vertical or oblique orientation is determined by the LDH-containing separator layer (for example, an LDH dense film). This is a very advantageous property for the user. 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 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 the 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 the 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 direction perpendicular to the separator layer. Here, it is needless to say that the “vertical direction” in this specification includes not only a strict vertical direction but also a substantially vertical direction similar thereto. 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. Due to the orientation in the direction perpendicular to the layer, the peak of the (003) plane is not substantially detected or is 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 the vertical direction, the LDH layered structure also faces the vertical direction. As a result, when the separator layer surface is measured by the X-ray diffraction method, the (00l) plane (l is 3 and 6). This is because the peak does not appear or becomes difficult to appear. In particular, the (003) plane peak tends to be stronger than the (006) plane peak when it exists, so it can be said that it is easier to evaluate the presence of vertical orientation than the (006) plane peak. . 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, and any combination thereof, and more preferable. Is alumina, zirconia, titania, and any combination thereof, particularly preferably 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 range, it is possible to promote nucleation of Al (OH) ₃ instead of LDH. 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, whereby the raw material aqueous solution contains nitrate ions in addition to magnesium ions and aluminum ions. In this case, the molar ratio (urea / NO ₃ ⁻ ) of urea to nitrate ions (NO ₃ ⁻ ) in the raw material aqueous solution is preferably 2 to 6, and more preferably 4 to 5.

  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, the LDH is perpendicular to or close to the porous substrate (that is, the LDH plate-like particles are such that their plate surfaces intersect the surface (substrate surface) of the porous substrate perpendicularly or obliquely. It is preferable to adopt a configuration or arrangement in which the growth is performed in any 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 are oriented in the vertical direction advantageous for conduction. That is, the LDH film typically does not have water permeability (desirably water permeability and air permeability) due to high density. Further, 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 are oriented so that their plate surfaces perpendicularly or obliquely intersect the surface of the porous substrate. Typically, it is 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.

Example 1 : Evaluation of various adhesives (1) Evaluation of adhesive by immersion in aqueous potassium hydroxide solution The adhesives A to E shown below were evaluated by immersion in an aqueous potassium hydroxide solution.
<Adhesives A to E>
-Epoxyamide adhesive A (EP007, manufactured by Cemedine)
-Epoxy adhesive B (EPOXY RESIN XNR3114 (M15) and HARDNER XNH3114, manufactured by Nagase ChemteX Corporation)
-Epoxy adhesive C (EP171, manufactured by Cemedine)
-Epoxyamide adhesive D (EP008, manufactured by Cemedine)
-Epoxy adhesive E (EPOXY RESIN XN1244, manufactured by Nagase ChemteX Corporation)

  For each of the adhesives A to E, the Si content (% by weight) was measured by ICP emission spectroscopy. The measurement results were as shown in Table 1.

  First, the adhesive was solidified to prepare a sample of the adhesive solidified body having a size of 20 mm × 20 mm × 1 mm. The solidification of the adhesive was performed based on information such as instruction manuals provided for each adhesive used (all commercially available). The sample was immersed in a 9 mol / L KOH aqueous solution (50 cc to 60 cc) and stored in a constant temperature dryer (manufactured by ASONE, constant temperature dryer SOFW-300S) set at 90 ° C. The sample was taken out when 504 hours passed after immersion. The sample taken out was washed with ion exchange water, and washing was repeated until the pH of the washing solution after washing was less than 8. At this time, the pH was confirmed with a litmus paper (Aswan, stick pH paper 7.0-14.0). The washed sample was dried at room temperature in an air atmosphere for 12 hours or more. The dried sample was embedded in an epoxy resin, cut with a leuter, and the cut surface was polished with # 4000 polishing paper. The polished sample was milled with an ion milling device (IM4000 manufactured by Hitachi High-Technologies) at an acceleration voltage of 5 V for 3 hours. The milled cross section was observed and analyzed with SEM and EDS. The SEM observation was performed using JSM-6610LV manufactured by JEOL Ltd. at a magnification of 200 times. In addition, EDS analysis uses x-act manufactured by Oxford Instruments, and the area where the contrast between the adhesive and the epoxy resin is changed on the SEM image is the adhesive surface, and semi-quantitatively from the surface of the sample to a depth of 50 μm every 10 μm. The analysis was performed. The SEM image obtained for the adhesive A and FIG. 6 are shown. Moreover, the EDS analysis result (K density | concentration in each distance from the surface) obtained about the adhesive agent A is shown in FIG. It can be seen from FIG. 7 that the plot indicated by the arrow corresponds to the maximum potassium concentration at a depth of 50 μm from the surface of the adhesive solidified body. The maximum potassium concentration measured for each adhesive was as shown in Table 1.

(2) Durability Test For each of the adhesives A to E, the durability of the bonding interface between the resin frame and the adhesive and the durability of the adhesive itself were evaluated by the following procedure. First, as shown in FIG. 8, a porous substrate 320 (alumina porous substrate) is placed on a resin frame 324 (made of modified polyphenylene ether) having an opening at the center, and the porous substrate 320 The adhesive 322 is uniformly applied to one side and the outer periphery, and the one side of the porous base material 320 and the joint portion between the resin frame 324 and the porous base material 320 are completely sealed with the adhesive 322. did. The adhesive 322 was cured, and an evaluation sample 321 sealed in an airtight and liquid-tight manner with the adhesive 322 was obtained. This sample for evaluation was assembled in the sample holder 316 as shown in FIGS. 17A and 17B. Except for the above, the He permeability (cm / (min · atm)) was measured by the same procedure as “(6b) He permeation measurement” in Example 5 to be described later, and the presence or absence of gas leakage was confirmed.

  Next, in order to investigate the durability of the adhesive in a KOH aqueous solution, the evaluation sample 321 prepared in the same manner as above was immersed in a 9 mol / L KOH aqueous solution at 90 ° C. for 1 week, 2 weeks, 3 weeks or 5 weeks. Then, it was assembled in the sample holder 316 in the same manner as described above. Except for the above, the He permeability (cm / (min · atm)) was measured by the same procedure as “(6b) He permeation measurement” in Example 5 described later, and the presence or absence of gas leakage was confirmed.

The measurement results were as shown in Table 1. A He permeability of 0 means that He did not pass through, that is, no deterioration or peeling occurred at the adhesive and its bonding interface. The larger the value of He permeability, the higher the adhesive and its bonding. It means that the degree of deterioration or peeling at the interface was high. Based on this, based on the results obtained, the durability of the adhesive was evaluated according to the following criteria.
-Evaluation A: Excellent durability against KOH aqueous solution.
-Evaluation B: Good durability against KOH aqueous solution.
-Evaluation C: Inferior in durability to KOH aqueous solution.

About the sample of the adhesive D determined to be undesirable evaluation C, the surface of the adhesive 322 (the porous substrate 320 of the porous base material 320) is the same as the above-mentioned “(1) Evaluation of the adhesive by immersion in an aqueous potassium hydroxide solution”. When the potassium (K) concentration and the silicon (Si) concentration at each distance from the opposite surface) were observed and analyzed by SEM and EDS, the results shown in FIGS. 9 and 10 were obtained. From the results shown in FIGS. 9 and 10, it can be seen that the longer the immersion time in the KOH aqueous solution, the smaller the amount of Si in the adhesive, while the longer the immersion time in the KOH aqueous solution, the higher the K amount in the adhesive. . This suggests that SiO ₂ in the adhesive D is dissolved in the KOH aqueous solution. That is, it is considered that the erosion of the SiO ₂ contained in the adhesive by the KOH aqueous solution caused the deterioration of the adhesive.

  From the results shown in Table 1, it can be seen that the sample having a lower maximum potassium concentration or the sample having a lower Si content in the adhesive does not leak gas even when immersed in a KOH aqueous solution for a long period of time. That is, it can be seen that the above-mentioned maximum potassium concentration and Si content are effective as indices for evaluating the long-term alkali resistance of the adhesive.

Example 2 : 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): (methylcellulose) : (Ion-exchanged water) mass ratio was 10: 1: 5, and then 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 The threshold value of the histogram is adjusted in the procedure of [gradation] to create a black and white binary image, 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 is the porosity (%) It was done by doing. This porosity measurement was performed on a 6 μm × 6 μm region on the surface of the porous substrate. FIG. 11 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 film sample Film sample with X-ray diffractometer (RINT TTR III manufactured by Rigaku Corporation) under the measurement conditions of voltage: 50 kV, current value: 300 mA, measurement range: 10-70 ° As a result, the XRD profile shown in FIG. 12 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 the XRD profile shown in FIG. 12, a peak (peak marked with a circle in the figure) due to alumina constituting the porous substrate on which the film sample is formed is also observed. .

(5b) Observation of microstructure The surface microstructure of the film sample was observed at an acceleration voltage of 10 to 20 kV using a scanning electron microscope (SEM, JSM-6610LV, manufactured by JEOL). FIG. 13 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. 14 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] The threshold value of the histogram is adjusted to create a monochrome binary image, and 4) the value obtained by dividing the number of pixels occupied by the black portion by the total number of pixels in the image is the porosity (%). It went by. 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. 15A, the composite material sample 120 obtained in the above (1) (one cut into 1 cm × 1 cm square) has a 0.5 cm × 0.5 cm square at the center on the film sample side. The silicon rubber 122 provided with the opening 122a was adhered, and the obtained laminate was adhered between two acrylic containers 124 and 126. The bottom of the acrylic container 124 disposed on the silicon rubber 122 side is pulled out, whereby the silicon rubber 122 is bonded to the acrylic container 124 with the opening 122a open. On the other hand, the acrylic container 126 disposed on the porous substrate side of the composite material sample 120 has a bottom, and ion-exchanged water 128 is contained in the container 126. At this time, Al and / or Mg may be dissolved in the ion exchange water. That is, by assembling the components upside down after assembly, the constituent members are arranged so that the ion exchange water 128 is in contact with the porous substrate side of the composite material sample 120. After assembling these components, the total weight was measured. Needless to say, the container 126 has a closed vent hole (not shown) and is opened after being turned upside down. As shown in FIG. 15B, the assembly was placed upside down and held at 25 ° C. for 1 week, and then the total weight was measured again. At this time, when water droplets were attached to the inner side surface of the acrylic container 124, 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. 16A and 16B, an acrylic container 130 without a lid and an alumina jig 132 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. The alumina jig 132 is formed with an opening 132a having a diameter of 5 mm, and a depression 132b for placing a film sample is formed along the outer periphery of the opening 132a. An epoxy adhesive 134 was applied to the depression 132 b of the alumina jig 132, and the film sample 136 b side of the composite material sample 136 was placed in the depression 132 b and adhered to the alumina jig 132 in an air-tight and liquid-tight manner. Then, the alumina jig 132 to which the composite material sample 136 is bonded is 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. A measurement sealed container 140 was obtained. 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 sealed container 140 is sufficiently airtight and liquid tight, and the membrane sample 136b side of the composite material sample 136 is exposed to the internal space of the measurement sealed container 140, while the composite material sample The porous substrate 136 a side of 136 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 membrane sample 136b 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). Whether or not helium gas bubbles were generated in the water from the composite material sample 136 was observed. As a result, generation of bubbles due to helium gas was not observed. Therefore, it was confirmed that the membrane sample 136b has high density so as not to have air permeability.

Example 3 Production and Evaluation of Nickel Zinc Battery (1) Preparation of Separator with Porous Substrate LDH film on alumina substrate (size: 5 cm × 8 cm) as a separator with porous substrate by the same procedure as in Example 1 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 the porous substrate obtained above, a nickel zinc battery was assembled in the following procedure.

  First, a rectangular parallelepiped case main body made of ABS resin from which the case upper lid was removed was prepared. A separator with a porous base material (LDH film on an alumina base material) was inserted near the center of the case main body, and three sides thereof were fixed to the inner wall of the case main body using an epoxy resin 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. 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 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. Thus, a nickel zinc battery was obtained.

(5) Evaluation The manufactured nickel zinc 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. 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. The separator with the porous base material was kept bonded to the cuboid case body made of ABS resin in a good adhesion state.

Example 4 : Preparation of zinc-air secondary battery (1) Preparation of separator with porous substrate By a procedure similar to that of Example 1, a separator with porous substrate (hereinafter simply referred to as a separator) was used as an LDH film on an alumina substrate. 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 mixing 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 LDH membrane of the separator to obtain a separator / intermediate layer laminate. The thickness of the intermediate layer is 30 μm. The separator / intermediate layer laminate thus obtained is pressure-bonded with the air electrode layer / current collector laminated sheet prepared previously so that the air electrode layer side is in contact with the intermediate layer, thereby obtaining an air electrode sample with a separator.

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

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

(6) Assembly of battery Using the obtained air electrode with separator, negative electrode plate, and third electrode, a zinc-air secondary battery having a horizontal structure is manufactured in the following procedure. First, a container without a lid (hereinafter referred to as a resin container) made of ABS resin and having a rectangular parallelepiped shape is prepared. The negative electrode plate is placed on the bottom of the resin container so that the side on which the negative electrode active material is coated faces upward. At this time, the negative electrode current collector is in contact with the bottom of the resin container, and the end of the negative electrode current collector is connected to an external terminal provided through the side surface of the resin container. Next, a third electrode is provided at a position higher than the upper surface of the negative electrode plate on the inner wall of the resin container (that is, a position that does not contact the negative electrode plate and does not participate in the charge / discharge reaction), and the nonwoven fabric separator contacts the third electrode. Deploy. 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 an epoxy resin adhesive to the outer periphery of the opening to give airtightness and liquid tightness. Seal 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. Thus, the zinc-air secondary battery of the present invention 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 side reaction from the negative electrode 34 can be brought into contact with the third electrode and returned to water through the above-described reaction. That is, a highly reliable zinc-air secondary battery that can cope with the problem of hydrogen gas generation while having a configuration suitable for preventing both short-circuiting due to zinc dendrite and mixing of carbon dioxide is provided. . In addition, by adopting a configuration in which the third electrode is connected to the air electrode via an external circuit, hydrogen gas that can be generated by a side reaction from the negative electrode is brought into contact with the third electrode, and the following reaction is performed:
Third electrode: H ₂ + 2OH ⁻ → 2H ₂ O + 2e ⁻
Positive electrode discharge: It can be returned to water by O ₂ + 2H ₂ O + 4e ⁻ → 4OH ⁻ .

Example 5
In this example, samples 1 to 10 were prepared as follows as LDH-containing composite material samples (separator samples with porous substrates) in which a layered double hydroxide (LDH) dense film was formed on a porous substrate. .

(1) Production of porous substrate Boehmite (manufactured by Sasol, DISPAL 18N4-80), methylcellulose, and ion-exchanged water are mixed at a weight ratio of 10: 1: (boehmite) :( methylcellulose) :( ion-exchanged water). After weighing so as to be 5, kneaded. The obtained kneaded product was subjected to extrusion molding using a hand press and molded into a size of 2.5 cm × 10 cm × thickness 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.

  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.

  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) Polystyrene spin coating and sulfonation For samples 1 to 6 only, polystyrene spin coating and sulfonation were performed on the porous substrate by the following procedure. That is, 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 the 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.

(4) 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 75 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.

(5) 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 (4) above and the porous substrate sulfonated in (3) above (Samples 1 to 6) or the porous substrate (samples 7 to 10) washed 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. Then, the layered double hydroxide alignment film was formed on the substrate surface by performing hydrothermal treatment at a hydrothermal temperature of 70 to 75 ° C. for 168 to 504 hours. At this time, ten kinds of alignment films having various denseness were produced by appropriately changing the conditions of the hydrothermal treatment. 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 1.0 to 2.0 μm. Thus, Samples 1 to 10 were obtained as LDH-containing composite material samples (hereinafter referred to as composite material samples). In addition, 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.

(6a) Identification of membrane sample Using an X-ray diffractometer (RINT TTR III manufactured by Rigaku Corporation), the crystal phase of the membrane sample is measured under the measurement conditions of voltage: 50 kV, current value: 300 mA, measurement range: 10 to 70 °. To obtain an XRD profile. About the obtained XRD profile, JCPDS card NO. Identification was performed using a diffraction peak of a layered double hydroxide (hydrotalcite compound) described in 35-0964. As a result, it was confirmed that each of the film samples 1 to 10 was a layered double hydroxide (LDH, hydrotalcite compound).

(6b) He permeation measurement A He permeation test was performed as follows to evaluate the denseness of the membrane samples 1 to 10 from the viewpoint of He permeability. First, the He transmittance measurement system 310 shown in FIGS. 17A and 17B was constructed. In the He permeability measurement system 310, 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 the denseness held in the sample holder 316 is measured. The membrane 318 is configured to be transmitted through one surface from 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. First, an adhesive 322 was applied along the outer periphery of the dense film 318 and attached to a resin frame 324 (made of ABS resin) having an opening at the center. Supporting members 328a and 328b (PTFE) having openings made of flanges from the outside of the sealing members 326a and 326b are provided with sealing members 326a and 326b on the upper and lower ends of the resin frame 324, respectively. Made). Thus, the sealed space 316b was partitioned by the dense film 318, the resin frame 324, the sealing member 326a, and the support member 328a. The dense film 318 is in the form of a composite material formed on the porous substrate 320, but the dense film 318 is disposed so that the dense film 318 side faces 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 through the gas supply pipe 334 and permeated through the dense film 318 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 permeating 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 dense film 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. The obtained results were as shown in Table 2 and FIG.

(6c) Zn permeation test In order to evaluate the denseness of the film samples 1 to 10 from the viewpoint of Zn permeation, a Zn permeation test was performed as follows. First, a Zn transmission measuring device 340 shown in FIGS. 18A and 18B was constructed. The Zn transmission measuring device 340 includes a flanged open tube (made of PTFE) in which a flange 362a is integrated with a first tank 344 configured with an L-shaped open tube, and a second configured with an L-shaped tube. A dense membrane in which a flanged opening pipe (made of PTFE) in which a flange 362b is integrated with a tank 346 is disposed so that the flanges 362a and 362b face each other, and a sample holder 342 is disposed between them. Zn was allowed to pass through from one surface to the other.

  The assembly of the sample holder 342 and its attachment to the apparatus 340 were performed as follows. First, an adhesive 356 was applied along the outer periphery of the dense film 352 and attached to a jig 358 (made of ABS resin) having an opening at the center. As shown in FIG. 18A, silicone rubber packing is provided as sealing members 360a and 360b on both sides of the jig 358, and a pair of flanged opening pipe flanges 362a from the outside of the sealing members 360a and 360b. , 362b. The dense film 352 is in the form of a composite material formed on the porous substrate 354, but the dense tank 352 side (the first aqueous solution 348 containing Zn is injected) is the first tank 344. It was arranged to face. The flanges 362a and 362b were firmly tightened to each other by fastening means 364 using screws so that no liquid leakage occurred between them.

On the other hand, a 9 mol / L aqueous KOH solution in which 2.5 mol / L of Al (OH) ₃ and 0.5 mol / L of ZnO were dissolved was prepared as the first aqueous solution 348 to be put in the first tank 344. When the Zn concentration C ₁ (mol / L) of the first aqueous solution was measured by ICP emission spectroscopic analysis, the values shown in Table 2 were obtained. Further, as the second aqueous solution 350 to be put in the second tank 346, a 9 mol / L KOH aqueous solution in which 2.5 mol / L of Al (OH) ₃ was dissolved was prepared without dissolving ZnO. In the measurement apparatus 340 in which the sample holder 342 previously fabricated is incorporated, the first aqueous solution 348 and the second aqueous solution 350 are injected into the first tank 344 and the second tank 346, respectively, and the densely held by the sample holder 342 is obtained. Zn was permeated through the film 352. In this state, Zn permeation was performed at time t shown in Table 2, and then the liquid volume V ₂ (ml) of the second aqueous solution was measured, and the Zn concentration C ₂ (mol / L) of the second aqueous solution 350 was determined. It was measured by ICP emission spectroscopy. The Zn permeation ratio was calculated using the obtained value. The Zn permeation ratio includes the Zn concentration C ₁ (mol / L) of the first aqueous solution before the start of Zn permeation, the liquid volume V ₁ (ml) of the first aqueous solution before the start of Zn permeation, and the second concentration after the end of Zn permeation. Zn concentration C ₂ (mol / L) of the aqueous solution, the liquid volume V ₂ (ml) of the second aqueous solution after completion of Zn permeation, the permeation time t (min) of Zn, and the film area S (cm through which Zn permeates) ² ), and the calculation was performed according to the formula (C ₂ × V ₂ ) / (C ₁ × V ₁ × t × S). The obtained results were as shown in Table 2 and FIG.

Claims (3)

A method for selecting an adhesive suitable for manufacturing an alkaline secondary battery,
Solidifying the adhesive to be evaluated into a plate-like adhesive solidified body having a thickness of 100 μm or more;
Immersing the adhesive solidified body in a 9.0 mol / L potassium hydroxide aqueous solution at 90 ° C. for 504 hours, and taking out the adhesive solidified body;
Washing the taken-out adhesive solidified body with ion-exchanged water until the pH of the washing liquid after washing becomes less than 8.
Drying the adhesive solidified body after washing;
The maximum potassium concentration at a depth of 50 μm from the surface of the adhesive solidified body after the drying was measured, and the adhesive that resulted in the adhesive solidified body having a maximum potassium concentration of 0.01 to 2.00 at% Selecting an adhesive suitable for the production of the alkaline secondary battery,
Only including,
The method in which the adhesive is an epoxy resin adhesive, and the content of Si in the adhesive is 0 to 1.7% by weight .   The method of claim 1, further comprising providing or using the selected adhesive in the manufacture of the alkaline secondary battery. The alkaline secondary battery is an alkaline secondary battery using a hydroxide ion conductive ceramic separator, and the alkaline secondary battery isolates a positive electrode, a negative electrode, an alkaline electrolyte, and the positive electrode and the negative electrode. Comprising a separator structure and a resin container containing at least the negative electrode and the alkaline electrolyte,
The separator structure includes a ceramic separator made of an inorganic solid electrolyte body having hydroxide ion conductivity, or includes the ceramic separator and a resin frame and / or a resin film surrounding an outer periphery of the ceramic separator. ,
The separator structure is bonded to the resin container via an adhesive and / or the ceramic separator is bonded to the resin frame and / or the resin film via an adhesive;
The method according to claim 1 or 2 , wherein the adhesive is selected as an adhesive suitable for manufacturing the alkaline secondary battery when evaluated by the method according to claim 1 or 2 .