JP6296879B2 - Electrode and air secondary battery using the same - Google Patents

Description

  The present invention relates to an electrode and an air secondary battery using the electrode.

  Since the air battery is supplied with oxygen, which is a positive electrode active material, from the outside of the battery, there is no need to accommodate the positive electrode active material in the battery. Therefore, a large amount of the negative electrode active material can be filled in the battery, and a very high energy density can be achieved.

An air battery includes a positive electrode including a positive electrode catalyst layer including a positive electrode catalyst having oxygen reducing ability and water oxidizing ability, a negative electrode using zinc, iron, aluminum, magnesium, lithium, hydrogen, or the like as a negative electrode active material, and an electrolytic solution. It is a battery which has. For example, when the negative electrode contains zinc, the discharge reaction of the air battery under alkaline conditions is represented by the following formula.
Positive electrode: O ₂ + 2H ₂ O + 4e ⁻ → 4OH ⁻
Negative electrode: Zn + 2OH ⁻ → ZnO + H ₂ O + 2e ⁻
Total reaction: 2Zn + O ₂ → 2ZnO

  Conventionally, batteries (secondary batteries, rechargeable batteries, storage batteries) that can store electricity by charging and can be used repeatedly are known. Development of batteries using oxygen as an active material is also underway. In the following description, a battery that uses oxygen in the air as an active material and can be repeatedly charged and discharged is referred to as an “air secondary battery” to distinguish it from the above-described air battery.

  As an air secondary battery, for example, Non-Patent Document 1 discloses an air secondary battery having an electrode containing a metal inorganic oxide.

Nae-Lih Wu et al, "" Effect of oxygenation on electrocatalysis of La0.6Ca0.4CoO3-x in bifunctional air electrode ", Electrochimica Acta 200315, 4815.

  However, the air secondary battery having an electrode containing a metal inorganic oxide described in Non-Patent Document 1 has a problem that charge / discharge activity is insufficient.

  This invention is made | formed in view of such a situation, and provides the air secondary battery which has an electrode which can provide the air secondary battery which has the outstanding charging / discharging activity, and this electrode.

That is, the present invention provides the following inventions.
The present invention first provides an electrode comprising a metal complex having an oxygen reducing ability and a layered metal compound having an ability to oxidize water.
The present invention secondly provides the electrode described above, wherein the metal complex having the ability to reduce oxygen is a polynuclear metal complex.
Thirdly, the present invention provides the electrode described above containing a first transition metal atom or ion as a central metal of the metal complex having the ability to reduce oxygen.
Fourthly, in the present invention, the layered metal compound having the ability to oxidize water is [M ²⁺ _1-x M ³⁺ _x (OH) ₂ ] ^{x +} [A ⁿ⁻ _{x / n} · mH ₂ O] ^x−. (Wherein M is a transition metal element, A ⁿ⁻ is an n-valent anion, x is 0 <x <1, m and n are real numbers greater than 0) An electrode is provided.
The present invention fifthly provides the electrode described above, wherein M is manganese, iron, cobalt, nickel, copper or zinc.
Sixth, the present invention provides the electrode as described above, wherein the n-valent anion is a monovalent hydroxide ion.
Seventh, the present invention provides an air secondary battery having the electrode described above.

  According to the present invention, an air secondary battery having excellent charge / discharge activity can be provided.

It is a schematic diagram which shows an example of the air secondary battery of this embodiment.

Hereinafter, this embodiment will be described in detail.

<Electrode>
The electrode of the present invention includes a metal complex having an oxygen reducing ability and a layered metal compound having an ability to oxidize water. Here, the ability to reduce oxygen means that oxygen can be reduced to hydroxide ions, and the ability to oxidize water means that water can be oxidized to hydroxide ions.

(Metal complex with oxygen reducing ability)
Examples of the metal complex having oxygen reducing ability include mononuclear metal complexes such as metal porphyrins and metal phthalocyanines, and polynuclear metal complexes having a plurality of metal atoms or metal ions in one molecule.

  The central metal of the metal complex is preferably a first transition metal atom or ion.

Specific structural formulas are exemplified for the mononuclear metal complex. M represents a metal atom or a metal ion. The hydrogen atom in the structural formula may be substituted with another substituent.

Specific structural formulas are exemplified for the polynuclear metal complex. M represents a metal atom or a metal ion. A plurality of M may be the same or different. The hydrogen atom in the structural formula may be substituted with another substituent. Note that the charge of the polynuclear metal complex is omitted.

(Method for producing metal complex having oxygen reducing ability)
Next, a method for synthesizing a metal complex having oxygen reducing ability that is preferably used in the present invention will be described.
The metal complex having the ability to reduce oxygen that can be used in the present invention is prepared by, for example, synthesizing a ligand compound organically and then adding the resulting compound to a reactive agent (hereinafter referred to as a metal atom or metal ion). , "Metal-imparting agent") and mixed and reacted. The amount of the metal-imparting agent to be reacted is not particularly limited, and the amount of the metal-imparting agent may be adjusted according to the target metal complex. It is preferable to react.

Specific structural formulas are exemplified for the ligand compound. The hydrogen atom in the structural formula may be substituted with another substituent.

  Examples of the metal-imparting agent include acetate, fluoride, chloride, bromide, iodide, sulfate, carbonate, nitrate, hydroxide, perchlorate, trifluoroacetate, trifluoromethanesulfonic acid, tetrafluoro Examples thereof include borates, hexafluorophosphates, tetraphenyl borates and the like, and acetates are particularly preferable. Examples of the acetate salt include cobalt acetate (II), cobalt acetate (III), iron acetate (II), iron acetate (III), manganese acetate (II), manganese acetate (III), nickel acetate (II), acetic acid Examples thereof include copper (II) and zinc acetate (II), preferably cobalt acetate.

  The metal imparting agent may be a hydrate such as cobalt acetate (II) tetrahydrate, manganese acetate (II) tetrahydrate, manganese acetate (III) dihydrate, nickel acetate ( II) Tetrahydrate, copper acetate (II) monohydrate, zinc acetate (II) dihydrate.

  The step of mixing the ligand compound and the metal imparting agent is performed in the presence of a suitable solvent. As a solvent (reaction solvent) used in the reaction, water; organic acids such as acetic acid and propionic acid; amines such as aqueous ammonia and triethylamine; methanol, ethanol, n-propanol, isopropyl alcohol, 2-methoxyethanol, Alcohols such as 1-butanol and 1,1-dimethylethanol; ethylene glycol, diethyl ether, 1,2-dimethoxyethane, methyl ethyl ether, 1,4-dioxane, tetrahydrofuran, benzene, toluene, xylene, mesitylene, durene, Aromatic hydrocarbons such as decalin; halogen solvents such as dichloromethane, chloroform, carbon tetrachloride, chlorobenzene, 1,2-dichlorobenzene, N, N′-dimethylformamide, N, N′-dimethylacetamide, N-methyl- 2-pyrrolidone, Examples thereof include dimethyl sulfoxide, acetone, acetonitrile, benzonitrile, triethylamine, and pyridine. In addition, these reaction solvents may be used individually by 1 type, or may use 2 or more types together. The solvent is preferably a solvent in which the aromatic compound serving as a ligand and the metal-imparting agent can be dissolved.

  The mixing temperature of the ligand compound and the metal imparting agent is preferably −10 ° C. or higher and 250 ° C. or lower, more preferably 0 ° C. or higher and 200 ° C. or lower, and further preferably 0 ° C. or higher and 150 ° C. or lower.

  The mixing time of the ligand compound and the metal-imparting agent is preferably 1 minute or more and 1 week or less, more preferably 5 minutes or more and 24 hours or less, and further preferably 1 hour or more and 12 hours or less. In addition, it is preferable to adjust the said mixing temperature and mixing time in consideration of the kind of the said ligand compound and a metal provision agent.

  The generated metal complex can be removed from the solvent by selecting and applying a suitable method from known recrystallization methods, reprecipitation methods, and chromatography methods. At this time, a plurality of the methods are combined. May be. Depending on the type of the solvent, the produced polynuclear metal complex may be precipitated. In this case, the precipitated metal complex may be separated by filtration or the like and then washed, dried, or the like.

The said metal complex may be used individually by 1 type, respectively, and 2 or more types may be mixed and used for it.
(Layered metal compound with water oxidation ability)

In the present invention, examples of the layered metal compound include layered double hydroxides and layered metal oxides, and layered double hydroxides are preferred. Here, the layered double hydroxide represents a compound having a structure in which metal hydroxide layers and layers composed of anions and interlayer water are alternately laminated, and the layered metal oxide is a metal having a layered structure. Represents an oxide.
(Layered metal oxide with water oxidation ability)

An example of the composition of the layered metal oxide having the ability to oxidize water is a composition represented by BC _y O _z . (In the formula, B and C are metal elements, and y and z represent a real number larger than 0.)

  As the metal element contained in the layered metal oxide, a typical metal and a transition metal can be used.

  The range of the real number of y is preferably 0 <y <6, more preferably 1 <y <5, and further preferably 1 <y <4.

  The range of the real number of z is preferably 0 <z <12, more preferably 1 <z <8, and further preferably 2 <z <5.

(Layered double hydroxide with water oxidation ability)
An example of the composition of the layered double hydroxide having water oxidizing ability is [M ²⁺ _1-x M ³⁺ _x (OH) ₂ ] ^{x +} [A ⁿ⁻ _{x / n} · mH ₂ O] ^x− The composition represented is mentioned. (Wherein, M is a transition metal element, M ²⁺ is a divalent transition metal ion, M ³⁺ is a trivalent transition metal ions, A ^n-n-valent anion, x is 0 <x <1 and m And n represents a real number greater than 0.)

  As the metal element contained in the layered double hydroxide, a transition metal can be used.

  As said M, 1 or more types chosen from the group which consists of manganese, iron, cobalt, nickel, copper, and zinc can be used, More preferably, it is 1 or more types chosen from the group which consists of nickel, iron, and cobalt More preferably, it is nickel and / or iron.

^{Examples of the An −} include hydroxide ions, fluoride ions, chloride ions, bromide ions, iodide ions, carbonate ions, nitrate ions, sulfate ions, acetate ions, and the like. From the viewpoint of improving activity, more preferred are hydroxide ions, chloride ions, bromide ions, and carbonate ions, and even more preferred are hydroxide ions.

  The range of the real number of x is preferably 0 <x <1, more preferably 0.1 <x <0.8, and still more preferably 0.2 <x <0.5.

  The range of the real number of m is preferably 0 <m <20, more preferably 0 <m <15, and even more preferably 1 <m <10.

The layered double hydroxide preferably has high water oxidizing ability. As an index of high water oxidizing ability, for example, a catalyst layer made of carbon, layered double hydroxide and polytetrafluoroethylene (PTFE) and a gas diffusion layer made of carbon black, triton and PTFE are placed on a nickel mesh. The electrode was made by pressing, and when the electrode was evaluated using a potentiostat in 8M potassium hydroxide aqueous solution with platinum as the counter electrode, the current density at 1 V with respect to the silver / silver chloride electrode Is preferably 150 mA / cm ² or more.

(Method for producing layered metal oxide)
A method for synthesizing a layered metal oxide suitably used in the present invention will be described. The layered metal oxide may be synthesized by any known method, for example, by the following method.

  The layered metal oxide can be obtained by mixing and baking two or more selected from the group consisting of metal oxides and metal salts.

  As a method for mixing the metal oxide and the metal salt, any known method may be used. For example, they may be mixed using an agate mortar.

  As a method for firing the mixture of the metal oxide and the metal salt, any known method may be used. For example, the mixture may be fired by heating at 900 ° C. in an oxygen atmosphere.

(Method for producing layered double hydroxide)
Next, a method for synthesizing the layered double hydroxide suitably used in the present invention will be described. The layered double hydroxide may be produced by any known method, for example, it can be produced by the following method.

  The layered double hydroxide can be obtained by filtering a hydrothermally synthesized metal salt aqueous solution. Hydrothermal synthesis is a chemical reaction performed in a high-temperature and high-pressure solvent, and is used for the synthesis of substances that are difficult to dissolve in a normal-temperature and normal-pressure solvent.

  Examples of the metal salt include acetate, fluoride, chloride, bromide, iodide, sulfate, carbonate, nitrate, hydroxide, phosphate, perchlorate, trifluoroacetate, trifluoromethanesulfone. Examples thereof include acids, tetrafluoroborate, hexafluorophosphate, tetraphenylborate and the like, and acetate, chloride, nitrate and hydroxide are particularly preferable. Examples of the acetate salt include cobalt acetate (II), cobalt acetate (III), iron acetate (II), iron acetate (III), manganese acetate (II), manganese acetate (III), and nickel acetate (II). It is done. Examples of the chloride include cobalt (II) chloride, iron (II) chloride, iron (III) chloride, manganese (II) chloride, and nickel (II) chloride. Examples of the nitrate include cobalt nitrate ( II), iron nitrate (II), iron nitrate (III), manganese nitrate (II), nickel nitrate (II), and hydroxides include, for example, cobalt hydroxide (II), iron hydroxide ( II), manganese hydroxide (II), nickel hydroxide (II). Preferred are cobalt (II) acetate, nickel (II) acetate, and iron (III) nitrate.

  The metal salt may be a hydrate. Examples of the hydrate include cobalt acetate (II) tetrahydrate, manganese acetate (III) dihydrate, nickel acetate (II) tetrahydrate. , Nickel (II) acetate tetrahydrate, and iron (III) nitrate nonahydrate.

An organic solvent such as methanol, ethanol, tetrahydrofuran (hereinafter referred to as “THF”), N, N′-dimethylformamide (hereinafter referred to as “DMF”) or the like may be added to the aqueous solution of the metal salt.

  Further, an aqueous solution of sodium hydroxide, sodium carbonate, sodium nitrate or the like may be added to the aqueous solution of the metal salt.

  The hydrothermal synthesis temperature of the metal salt aqueous solution is preferably 50 ° C. or higher and 300 ° C. or lower, more preferably 60 ° C. or higher and 270 ° C. or lower, and further preferably 80 ° C. or higher and 250 ° C. or lower.

  The time for hydrothermal synthesis of the aqueous solution of the metal salt is preferably 1 minute or more and 1 week or less, more preferably 5 minutes or more and 24 hours or less, and further preferably 10 minutes or more and 12 hours or less.

  The obtained layered double hydroxide can be identified using powder X-ray diffraction, elemental analysis, infrared spectroscopy and the like.

  The said layered double hydroxide may be used individually by 1 type, and 2 or more types may be mixed and used for it. When two or more kinds of layered double hydroxides are mixed and used, they may be mixed by any known method. For example, they may be mixed in an agate mortar.

  The metal complex and the layered double hydroxide may be mixed by any known method. For example, they may be mixed in an agate mortar.

(electrode)
The electrode of the present invention is composed of an electrode catalyst and a current collector.

  The electrode of the present invention contains, as an electrode catalyst, a metal complex having an oxygen reducing ability and a layered metal compound having an ability to oxidize water, but may contain other electrode catalysts in addition to these. Furthermore, the electrode may contain a conductive material and a binder. The conductive material may be any material that can improve the conductivity of the electrode, and is preferably carbon.

  In the electrode, each of the constituent components such as the other electrode catalyst, conductive material and binder may be used alone or in combination of two or more.

Since the current collector has a role of supplying current to the electrode catalyst, the material of the current collector may be conductive. Examples of preferable positive electrode current collectors include metal plates, metal foils, metal meshes, metal sintered bodies, carbon paper, and carbon cloth.
Examples of the metal in the metal mesh and the metal sintered body include simple metals such as nickel, copper, chromium, iron, titanium, and alloys including two or more of these metals, such as nickel, copper, and stainless steel (iron-nickel). -Chromium alloy) is preferred.

  Examples of the electrode of the present invention include an electrode for an air secondary battery, an electrode for water electrolysis, a catalyst for producing hydrogen peroxide, a catalyst for oxidation-reduction reaction, and an oxygen sensor.

  When the electrode is used as an electrode for an air secondary battery, it is particularly preferable to use it as a positive electrode.

(Air secondary battery)
The air secondary battery of the present embodiment includes the negative electrode containing one or more negative electrode active materials selected from the group consisting of zinc alone and a zinc compound, and an electrolyte, using the electrode of the present invention as a positive electrode.

FIG. 1 is a schematic cross-sectional view illustrating an embodiment of an air secondary battery according to this embodiment.
The air secondary battery 1 shown here includes a positive electrode catalyst layer 11 including the electrode catalyst, a positive electrode current collector 12, a negative electrode active material layer 13 including the negative electrode active material, a negative electrode current collector 14, an electrolyte solution 15, and these. A container (not shown) is provided.
The positive electrode current collector 12 is disposed in contact with the positive electrode catalyst layer 11 to constitute a positive electrode. Further, the negative electrode current collector 14 is disposed in contact with the negative electrode active material layer 13, and these constitute a negative electrode. Further, a positive electrode terminal (lead wire) 120 is connected to the positive electrode current collector 12, and a negative electrode terminal (lead wire) 140 is connected to the negative electrode current collector 14.
The positive electrode catalyst layer 11 and the negative electrode active material layer 13 are disposed to face each other, and the electrolyte 15 is disposed so as to be in contact with them.
The air secondary battery according to the present embodiment is not limited to the one shown here, and a part of the configuration may be changed as necessary.

(Cathode layer)
The positive electrode catalyst layer of the present invention contains, as an electrode catalyst, a metal complex having an oxygen reducing ability and a layered metal compound having an ability to oxidize water, but may contain other electrode catalysts in addition to these. Furthermore, the electrode preferably contains a conductive material and a binder. The conductive material may be any material that can improve the conductivity of the electrode, and is preferably carbon.

  Examples of the carbon include “Norrit” (manufactured by NORIT), “Ketjen black” (manufactured by Lion), “Vulcan” (manufactured by Cabot), “Black Pearls” (manufactured by Cabot), “acetylene black” (electric (Manufactured by Kagaku Kogyo Co., Ltd.) (all are trade names) carbon black; fullerenes such as C60 and C70; carbon fibers such as carbon nanotubes, multiwall carbon nanotubes, double wall carbon nanotubes, single wall carbon nanotubes, carbon nanohorns, graphene, Graphene oxide can be exemplified, and carbon black is preferable.

  The carbon may be used in combination with a conductive polymer such as polypyrrole or polyaniline.

  Examples of the binder include an electrode catalyst, a conductive material, and the like that are bonded to each other. Examples of the binder include those that do not dissolve in an electrolytic solution used as an electrolytic solution, and are referred to as polytetrafluoroethylene (hereinafter referred to as “PTFE”). ), Tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene / hexafluoropropylene copolymer, tetrafluoroethylene / ethylene copolymer, polyvinylidene fluoride, polychlorotrifluoroethylene, chlorotrifluoroethylene / A fluororesin such as an ethylene copolymer is preferred.

  The metal complex having the ability to reduce oxygen contained in the positive electrode catalyst layer is preferably contained in the catalyst layer in an amount of 3 to 95% by weight, more preferably 5 to 50% by weight, and 10 to 30% by weight. It is particularly preferred.

  The compounding amount of the layered double hydroxide having a water oxidizing ability and the layered metal compound contained in the positive electrode catalyst layer is 0.1 to 10 parts by weight with respect to 1 part by weight of the metal complex having the ability to reduce oxygen. Preferably, it is 0.5 to 5 parts by mass, and particularly preferably 0.5 to 3 parts by mass.

The blending amount of the conductive material is preferably 0.5 to 30 parts by mass, more preferably 1 to 20 parts by mass, and 1 to 15 parts by mass with respect to 1 part by mass of the electrode catalyst. Particularly preferred. The blending amount of the binder is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 5 parts by mass, and 0.5 to 3 parts by mass with respect to 1 part by mass of the electrode catalyst. Part is particularly preferred.

In the positive electrode catalyst layer, each of the constituent components such as the other electrode catalyst, conductive material and binder may be used alone or in combination of two or more.
(Positive electrode current collector)

Since the positive electrode current collector has a role of supplying current to the electrode catalyst, the material may be any material as long as it is conductive. Examples of preferable positive electrode current collectors include metal plates, metal foils, metal meshes, metal sintered bodies, carbon paper, and carbon cloth.
Examples of the metal in the metal mesh and the metal sintered body include simple metals such as nickel, copper, chromium, iron, titanium, and alloys including two or more of these metals, such as nickel, copper, and stainless steel (iron-nickel). -Chromium alloy) is preferred.

  A gas diffusion layer may be sandwiched between the positive electrode catalyst layer and the positive electrode current collector.

(Negative electrode)
As the negative electrode in the present embodiment, one or more selected from the group consisting of zinc alone and a zinc compound can be used as the negative electrode active material. Examples of the zinc compound include zinc oxide, zinc hydroxide, and zinc alloy.

  As the zinc alloy, an alloy with 1 ppm to 3000 ppm of bismuth, preferably 100 ppm to 1000 ppm of bismuth may be used. Alternatively, a zinc alloy of 1 ppm to 3000 ppm indium, preferably 100 to 1000 ppm indium, or 1 ppm to 3000 ppm indium and 1 ppm to 3000 ppm bismuth, preferably 100 ppm to 1000 ppm indium and 100 ppm to 1000 ppm bismuth may be used. Good. By using these zinc alloys, hydrogen overvoltage of zinc can be reduced, and gas generation in the battery can be more reliably prevented.

  The negative electrode may be used in any shape of a plate shape, a granular shape, and a gel shape.

  The negative electrode current collector 14 may be the same as the positive electrode current collector 12.

(Electrolytes)
As the electrolyte, an electrolytic solution obtained by dissolving an electrolyte in a solvent can be used. As the solvent, water is preferable because ions are easily ionized.

  Examples of the electrolyte include potassium hydroxide, sodium hydroxide, ammonium chloride, potassium carbonate, potassium hydrogen carbonate, sodium carbonate, sodium hydrogen carbonate, sodium formate, potassium formate, sodium acetate, potassium acetate, tripotassium phosphate, hydrogen phosphate. Dipotassium, potassium dihydrogen phosphate, trisodium phosphate, disodium hydrogen phosphate, sodium dihydrogen phosphate, sodium borate, potassium sulfate, sodium sulfate, ammonium bicarbonate, ammonium formate, ammonium acetate, ammonium phosphate, Examples include ammonium dihydrogen phosphate, ammonium sulfate, and ammonium hydrogen sulfate. More preferably, potassium hydroxide, sodium hydroxide, ammonium chloride, potassium carbonate, potassium bicarbonate, sodium carbonate, sodium bicarbonate, sodium formate, potassium formate, sodium acetate, potassium acetate, tripotassium phosphate, dihydrogen phosphate Potassium, trisodium phosphate, and disodium hydrogen phosphate, and more preferably potassium hydroxide, sodium hydroxide, and ammonium chloride. The electrolyte may be an anhydride or a hydrate.

  The said electrolyte may be used individually by 1 type, respectively, and may use 2 or more types together, respectively.

  The concentration of the electrolyte in the electrolytic solution can be arbitrarily set depending on the use environment of the air secondary battery, but is preferably 1 to 99% by mass, more preferably 5 to 60% by mass. More preferably, it is -40 mass%.

  Citric acid, succinic acid, tartaric acid, or the like may be added to the electrolytic solution for the purpose of suppressing the generation of dendritic precipitates containing zinc.

  In addition, zinc oxide, zinc hydroxide, zinc sulfate, zinc formate, zinc acetate, or the like may be added to the electrolytic solution for the purpose of suppressing dissolution of zinc ions in the electrolytic solution during discharge.

  Alternatively, the electrolyte may be used as a gel electrolyte in which a water-absorbing polymer such as polyacrylic acid is absorbed.

<Other configurations>
The container accommodates the positive electrode catalyst layer 11, the positive electrode current collector 12, the negative electrode active material layer 13, the negative electrode current collector 14, and the electrolytic solution 15. Examples of the material of the container include resins such as polystyrene, polyethylene, polypropylene, polyvinyl chloride, and ABS resin, and metals that do not react with the contents such as the positive electrode catalyst layer 11.

In the air secondary battery 1, an oxygen diffusion film may be separately provided. The oxygen diffusion film is preferably provided outside the positive electrode current collector 12 (on the opposite side of the positive electrode catalyst layer 11). By doing so, oxygen (air) is preferentially supplied to the positive electrode catalyst layer 11 through the oxygen diffusion film.
The oxygen diffusion film may be a film that can suitably transmit oxygen (air), and examples thereof include a resin nonwoven fabric or a porous film. Examples of the resin include polyolefins such as polyethylene and polypropylene; polytetrafluoroethylene, A fluororesin such as polyvinylidene fluoride can be exemplified.

In the air secondary battery 1, a separator may be provided between them in order to prevent a short circuit due to contact between the positive electrode and the negative electrode.
The separator may be made of an insulating material capable of moving the electrolyte solution 15, and examples thereof include a resin nonwoven fabric or a porous film. Examples of the resin include polyolefins such as polyethylene and polypropylene; polytetrafluoroethylene, A fluororesin such as polyvinylidene fluoride can be exemplified. When the electrolytic solution 15 is used as an aqueous solution, it is preferable to use a hydrophilic resin as the resin.

  The shape of the secondary battery of the present invention is not particularly limited, and examples thereof include a coin type, a button type, a sheet type, a laminated type, a cylindrical type, a flat type, and a square type.

  The air secondary battery of the present embodiment is useful for a large-sized battery such as a power source for electric vehicles and a household power source, and is also useful as a small power source for mobile devices such as a mobile phone or a portable personal computer. .

  Hereinafter, the present invention will be described in more detail with reference to specific examples. Moreover, the analysis and evaluation in an Example were performed using the following.

(1) Powder X-ray diffraction (XRD) measurement device: X'Pert PRO MPD manufactured by PANalytical
X-ray tube: Cu-Kα
X-ray output: 45 kV-40 mA

(2) Measurement of ¹ H-NMR Device: INOVA300 manufactured by varian

[Synthesis Example 1]
<Synthesis of nickel iron-layered double hydroxide>
The flask was charged with 5.0 g (20 mmol) of nickel (II) acetate tetrahydrate and 20 ml of water to prepare a 0.2 M nickel acetate aqueous solution. Similarly, 4.0 g (10 mmol) of iron (III) nitrate nonahydrate and 10 ml of water were put in another flask to prepare a 0.2M iron nitrate aqueous solution. The prepared nickel acetate aqueous solution (10 ml) and iron nitrate aqueous solution (2 ml) were placed in a polytetrafluoroethylene crucible together with 20 ml of water and 20 ml of DMF, and the crucible was sealed with a stainless steel jacket. A stainless steel jacket was heated and stirred in an oil bath whose temperature was adjusted to 160 ° C. for 1 hour, then cooled to room temperature, and 30 mg of nickel iron-layered double hydroxide was collected by filtering off the yellow-colored precipitate formed in the reaction solution. Got.

The layered double hydroxide of [Synthesis Example 1] was subjected to X-ray diffraction (XRD).
2θ ( ^o ): 11.3, 22.7, 34.3, 38.6, 46.3, 61.6

[Synthesis Example 2]
<Synthesis of Metal Complex MC1>
Compound 3 was synthesized via Compound 1 and Compound 2 according to the following reaction formulas (1) to (3). And according to following Reaction formula (4), the metal complex MC1 was synthesize | combined using the compound 3 and the metal provision agent.

(Synthesis of Compound 1)

…（１）
（式中、Ｂｏｃはｔｅｒｔ−ブトキシカルボニル基であり、ｄｂａはジベンジリデンアセトンである。）

... (1)
(In the formula, Boc is a tert-butoxycarbonyl group, and dba is dibenzylideneacetone.)

  After the inside of the reaction vessel was filled with an argon gas atmosphere, 3.94 g (6.00 mmol) of 2,9- (3′-bromo-5′-tert-butyl-2′-methoxyphenyl) -1,10-phenanthroline ( Tetrahedron., 1999, 55, 8377.) 3.17 g (15.0 mmol) 1-N-Boc-pyrrole-2-boronic acid, 0.14 g (0.15 mmol) Tris ( Benzylideneacetone) dipalladium, 0.25 g (0.60 mmol) 2-dicyclohexylphosphino-2 ′, 6′-dimethoxybiphenyl and 5.53 g (26.0 mmol) potassium phosphate in 200 mL dioxane and 20 mL In a mixed solvent with water and dissolved, and stirred at 60 ° C. for 6 hours. After completion of the reaction, the mixture was allowed to cool, distilled water and chloroform were added, and the organic layer was extracted. The resulting organic layer was concentrated to give a black residue. This was purified by a silica gel column using chloroform as a developing solvent to obtain Compound 1. Identification data for the obtained compound 1 are shown below.

¹ H-NMR (300 MHz, CDCl ₃ ): δ (ppm) = 1.34 (s, 18H), 1.37 (s, 18H), 3.30 (s, 6H), 6.21 (m, 2H) ), 6.27 (m, 2H), 7.37 (m, 2H), 7.41 (s, 2H), 7.82 (s, 2H), 8.00 (s, 2H), 8.19 (D, J = 8.6 Hz, 2H), 8.27 (d, J = 8.6 Hz, 2H).

(Synthesis of Compound 2)

…（２）
（式中、Ｂｏｃはｔｅｒｔ−ブトキシカルボニル基である。）

... (2)
(In the formula, Boc is a tert-butoxycarbonyl group.)

  After making the inside of the reaction vessel a nitrogen gas atmosphere, 0.904 g (1.08 mmol) of Compound 1 was dissolved in 10 mL of anhydrous dichloromethane. While the obtained dichloromethane solution was cooled to −78 ° C., 8.8 mL (8.8 mmol) of a boron tribromide 1.0 M dichloromethane solution was slowly added dropwise thereto. After dropping, the mixture was stirred as it was for 10 minutes, and was left with further stirring until it reached room temperature. After 3 hours, the reaction solution was cooled to 0 ° C., a saturated aqueous sodium hydrogen carbonate solution was added, and extracted by adding chloroform, and the organic layer was concentrated. The resulting brown residue was purified with a silica gel column using chloroform as a developing solvent to obtain Compound 2. Identification data for the obtained compound 2 are shown below.

¹ H-NMR (300 MHz, CDCl ₃ ): δ (ppm) = 1.40 (s, 18H), 6.25 (m, 2H), 6.44 (m, 2H), 6.74 (m, 2H) ), 7.84 (s, 2H), 7.89 (s, 2H), 7.92 (s, 2H), 8.35 (d, J = 8.4 Hz, 2H), 8.46 (d, J = 8.4 Hz, 2H), 10.61 (s, 2H), 15.88 (s, 2H).

(Synthesis of Ligand Compound 3)

…（３）

... (3)

  In a reaction vessel, 0.061 g (0.10 mmol) of Compound 2 and 0.012 g (0.11 mmol) of benzaldehyde were dissolved in 5 mL of propionic acid and heated at 140 ° C. for 7 hours. Thereafter, propionic acid was distilled off from the obtained reaction solution, and the resulting black residue was purified by a silica gel column using a developing solvent in which a solvent in which chloroform and methanol were mixed at a volume ratio of 10: 1 was used. Ligand compound 3 was obtained. Identification data for the obtained ligand compound 3 are shown below.

¹ H-NMR (300 MHz, CDCl ₃ ): δ (ppm) = 1.49 (s, 18H), 6.69 (d, J = 4.8 Hz, 2H), 7.01 (d, J = 4. 8 Hz, 2H), 7.57 (m, 5H), 7.90 (s, 4H), 8.02 (s, 2H), 8.31 (d, J = 8.1 Hz, 2H), 8.47 (D, J = 8.1 Hz, 2H).

(Synthesis of metal complex MC1)

…（４）
（式中、Ａｃはアセチル基であり、Ｍｅはメチル基である。）

(4)
(In the formula, Ac is an acetyl group, and Me is a methyl group.)

After making the inside of the reaction vessel into a nitrogen gas atmosphere, 0.045 g (0.065 mmol) of compound 3 and 0.040 g (0.16 mmol) of cobalt acetate tetrahydrate containing 3 mL of methanol and 3 mL of chloroform The mixed solution was mixed and stirred for 5 hours while heating to 80 ° C. The resulting solution was concentrated to dryness to give a blue solid. This was washed with water to obtain a metal complex MC1. In the metal complex MC1 in the reaction formula, “(OAc)” indicates that one equivalent of acetate ion is present as a counter ion. Identification data of the obtained metal complex MC1 are shown below.
ESI-MS [M ·] ⁺ : m / z = 866.0

<Electrode evaluation>
[Example 1]
(Production of powder for gas diffusion layer)
Carbon black (acetylene black), Triton (Kishida Chemical) and water are mixed in a ratio of 1: 1: 30 (weight ratio), and PTFE (Daikin, D-210C) is added to 67% by weight with respect to carbon black. The mixture was added as such, pulverized with a miller for 5 minutes, filtered with suction, and dried at 120 ° C. for 12 hours. After drying, this was pulverized with a miller and heat-treated in air at 280 ° C. for 3 hours. The powder obtained here was pulverized again with a miller to obtain a gas diffusion layer powder.

(Preparation of powder for catalyst layer)
100 ml of water and 1 ml of 1-butanol are put in a beaker, 0.18 g of carbon (Ketjen Black 300EC), 0.16 g of nickel iron-layered double hydroxide prepared in Synthesis Example 1, and prepared in Synthesis Example 2 0.08 g of the resulting metal complex MC1 was added. After stirring for 2 hours, 0.16 g of PTFE (Daikin, D-210C) was added little by little and the mixture was further stirred for 1 hour. It was suction filtered, dried at 120 ° C. and ground with a miller to obtain catalyst layer powder.

(Production of electrodes)
Put aluminum foil on hot press mold, put nickel mesh (made by Nikolai Co., Ltd.) on top, fill 60mg of gas diffusion layer electrode powder, and fill 60mg of catalyst layer powder on gas diffusion layer powder. did. First, after cold pressing at a pressure of 80 kgf / cm ² , pressing was performed for 10 seconds using a hot press maintained at 350 ° C. to obtain an electrode. The reaction area of the electrode was 1.767 cm ² .

Electrode characteristic evaluation The electrode produced in the cell made from polytetrafluoroethylene was attached, and it measured using the potentiostat in 8M potassium hydroxide aqueous solution. Table 1 shows the oxygen reduction potential, water oxidation potential, and potential difference (V) at a current density of 50 mA / cm ² .

(measuring device)
Toho Giken Multipotentiostat MODEL PS-04
(Measurement condition)
Electrolyte solution: 8 mol / L potassium hydroxide aqueous solution Solution temperature: room temperature (23 ° C.)
Reference electrode: Silver / silver chloride electrode (saturated potassium chloride)
Counter electrode: Platinum electrode (Winkler type electrode)
Sweep speed: ± 25 mV / 180 seconds

[Comparative Example 1]
La _0.6 Ca _0.4 CoO _3-x was synthesized according to the method described in the literature (Electrochimica Acta 2003, 48, 1567). Evaluation was performed in the same manner as in Example 1 using La _0.6 Ca _0.4 CoO _3-x as a catalyst.

It can be seen that the electrode of the present invention has an excellent charge / discharge activity as a positive electrode of an air secondary battery because the potential difference between the oxygen reduction reaction and the water oxidation reaction is reduced.
From the above, the usefulness of the present invention was confirmed.

[Reference Example 1]
The metal complex MC1 obtained above, nickel iron-layered double hydroxide and carbon (trade name: Ketjen Black EC600JD, manufactured by Lion) were mixed at a mass ratio of 1: 1: 4, and in methanol at room temperature. After stirring for 15 minutes, the electrode catalyst Cat1 was obtained by drying at room temperature under reduced pressure of 200 Pa for 12 hours. Using the electrode catalyst 1, the oxygen reduction ability and the water oxidation ability were evaluated.

For the evaluation, a disk electrode having a disk portion made of glassy carbon (diameter 6.0 mm) was used. After adding 1 mL of 0.5 mass% Nafion (registered trademark) solution (solution obtained by diluting 5 mass% Nafion (registered trademark) solution with ethanol 10 times) to a sample bottle containing 1 mg of electrocatalyst Cat1, The sound wave was irradiated and dispersed for 15 minutes. After 7.2 μL of the obtained suspension was dropped on the disk portion of the electrode and dried, the electrode for measurement was obtained by drying in a dryer heated to 80 ° C. for 3 hours.
<Evaluation of oxygen reduction ability>
Using this measurement electrode, the current value of the oxygen reduction reaction was measured under the following measurement apparatus and measurement conditions. The current value is measured in a nitrogen-saturated state (under a nitrogen atmosphere) and an oxygen-saturated state (in an oxygen atmosphere). From the current values obtained in the measurement under an oxygen atmosphere, the current value is measured under a nitrogen atmosphere. The value obtained by subtracting the current value obtained by the measurement in was used as the current value of the oxygen reduction reaction. The current density was determined by dividing the current value by the surface area of the measurement electrode. The results are shown in Table 2.
The current density is a value at −0.8 V with respect to the silver / silver chloride electrode.

(measuring device)
RRDE-1 rotating ring disk electrode device manufactured by Nisatsu Kogyo Co., Ltd. ALS model 701C dual electrochemical analyzer (measurement conditions)
Cell solution: 0.1 mol / L potassium hydroxide aqueous solution (oxygen saturation or nitrogen saturation)
Solution temperature: 25 ° C
Reference electrode: Silver / silver chloride electrode (saturated potassium chloride)
Counter electrode: platinum wire Sweep speed: 10 mV / sec Electrode rotation speed: 1600 rpm

(Evaluation of water oxidation ability)
About the electrode catalyst obtained above, the same measurement electrode as in the case of the evaluation of the oxygen reducing ability was produced, and using this, the current value of the oxidation reaction of water was measured using the following measurement apparatus and measurement conditions. The current value was measured in a state where nitrogen was saturated, and the current density was determined by dividing the current value by the surface area of the measurement electrode. The results are shown in Table 2. The current density is a value at 1 V with respect to the silver / silver chloride electrode.

(measuring device)
RRDE-1 rotating ring disk electrode device manufactured by Nisatsu Kogyo Co., Ltd. ALS model 701C dual electrochemical analyzer (measurement conditions)
Cell solution: 1 mol / L sodium hydroxide aqueous solution (nitrogen saturation)
Solution temperature: 25 ° C
Reference electrode: Silver / silver chloride electrode (saturated potassium chloride)
Counter electrode: platinum wire Sweep speed: 10 mV / sec Electrode rotation speed: 900 rpm

  It can be seen from Reference Example 1 that the electrode catalyst containing both the metal complex (metal complex MC1) and the layered metal compound (nickel iron-layered double hydroxide) has oxygen reducing ability and water oxidizing ability.

  The electrode of the present invention can be used in the energy field, and the present invention can provide an air secondary battery having excellent charge / discharge activity.

  DESCRIPTION OF SYMBOLS 1 ... Air secondary battery, 11 ... Positive electrode catalyst layer, 12 ... Positive electrode collector, 120 ... Positive electrode terminal, 13 ... Negative electrode active material layer, 14 ... Negative electrode collector, 140 ... Negative electrode terminal, 15 ... Electrolyte

Claims (4)

A metal complex having reducing ability of oxygen, and a layered metal compound having oxidizing ability of water seen including,
The metal complex having the ability to reduce oxygen is a polynuclear metal complex,
Layered metal compound having oxidizing ability of the ^{_{water, [M 2+ 1-x M}} 3+ x (OH) 2] x + [A n- x / n · mH 2 O] x- ( wherein, M is nickel and iron , ^{a n-n-valent} anion, x is 0 <x <1 and m and n are real number greater than zero.) in the represented Ru electrode. The electrode according to claim 1, comprising a first transition metal atom or an ion as a central metal of the metal complex capable of reducing oxygen. The electrode according to claim 1 or 2 wherein the n-valent anion is monovalent hydroxide ion. The air secondary battery which has an electrode of any one of Claims 1-3 .

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