JP2013048012A - Air cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air cell in which dendrites are not generated at all and which has high safety, cycle characteristics, and moldability.SOLUTION: The air cell comprises an anode 4 provided with an organic compound having oxidation-reduction capability as an active material, a cathode 1 provided with an oxygen reduction catalyst, and an electrolyte 5 disposed between the anode 4 and the cathode 1. As the organic compound, a redox polymer which contains a residue having oxidation-reduction capability per repeating unit of the polymer is used.

Description

  The present invention relates to an air battery that can be repeatedly charged and discharged.

The air battery utilizes a four-electron reduction reaction of oxygen for the positive electrode reaction as shown in the formula (1).
O ₂ + 2H ₂ O + 4e ⁻ → 4OH ⁻ (1)

  By using oxygen as an active material, there is no need to incorporate an electrode active material in the battery cell. As a result, more negative electrode active materials can be mounted in the cell, and one of the batteries that can realize a high charge / discharge capacity. It is. Zinc-air primary batteries, which are widely used as air batteries, have high energy density and flat discharge voltage over a long period of time, so they are used for power supplies for hearing aids in small size and signal buoys in large size ( For example, Patent Documents 1 to 3).

  The development of air secondary batteries is expected to be used as a substitute for lead-acid batteries and as a large-capacity power source for electric vehicles from the viewpoint of environmental compatibility, economy, and lightness. Until now, air batteries using zinc, cobalt, aluminum, and iron for the negative electrode have been created, and reports have been made with a focus on achieving high discharge capacity (for example, Patent Documents 4 and 5).

  Also, lithium-air secondary batteries using metallic lithium as the negative electrode have been studied. By using lithium as the negative electrode, an air battery having an electromotive force of 2.0 V or more is possible. It is said that by using an organic solvent in the electrolyte, the metal negative electrode is prevented from reacting directly with oxygen and moisture as much as possible, and an air battery having a high energy density has been successfully constructed. On the other hand, since organic solvents are volatile and flammable, there is an unavoidable risk of heat generation and explosion due to a decrease in electrolyte during long-term storage and reaction with lithium. For this reason, when the battery is charged and discharged several tens of times, the cell is extremely deteriorated. Therefore, although it has been put into practical use as a primary battery, it has not been studied for practical use as a secondary battery. The creation of a novel technology that can upgrade an air battery as a disposable battery to a secondary battery with cycle characteristics that can be repeatedly charged and discharged is expected from the viewpoint of effective use of resources and omission of disposal procedures. (For example, Patent Documents 6 and 7, Non-Patent Document 1).

JP-A-9-92239 JP 2009-146846 A JP-A-2005-19145 JP-A-5-121105 JP 2006-093022 A JP 2009-032415 A JP 2008-293678 A

Journal of American Chemical Society, 128, 1390, 2006

Air batteries using metals such as lithium and zinc are extremely dangerous because the metal is reduced at the positive electrode during charging, so that a resinous electrodeposit, so-called dendrites, is generated, causing a short circuit between the two electrodes through the separator. , Leaving problems in terms of safety and cycle characteristics. Although dendrite suppression by additives has also been reported, high cycle characteristics (required performance to maintain a discharge capacity of 80% or more at 500 cycles) have not been achieved. In particular, in a lithium-air battery, a side reaction represented by the formula (2) occurs, and metal oxide accumulates on the positive electrode, causing a problem that the contact between the electrolyte and air is interrupted. ing.
2Li ⁺ + e ⁻ + O ₂ → Li ₂ O ₂ (2)

  For this reason, it cannot endure repetitive charging / discharging as a secondary battery, and has not been put into practical use as a secondary battery.

  An object of the present invention is to provide an air battery that does not generate any dendrites and has high safety, cycle characteristics, and moldability.

  As a result of intensive studies in consideration of such circumstances, the inventors have used organic materials that exhibit a reversible redox reaction as a negative electrode active material used in air batteries, and do not generate dendrites during charging and are highly safe. As a result, the present invention was completed.

  That is, the air battery of the present invention includes a negative electrode provided with an organic compound having oxidation-reduction ability as an active material, a positive electrode provided with an oxygen reduction catalyst, and an electrolyte layer disposed between the negative electrode and the positive electrode. It is characterized by doing.

  The organic compound is a quinone compound, an imide compound, a viologen compound, a phenazine compound, or a carboxylic acid compound.

  Further, the organic compound is a redox polymer containing a residue having redox ability per repeating unit of the polymer.

  In addition, the redox polymer has a main chain of polyolefin, polymethacrylic acid ester, polyacrylamide, polyamide, polyether, polyvinyl ether, polystyrene, polyphenylene sulfide, or a copolymer thereof.

  In addition, the redox polymer has benzoquinone, naphthoquinone, anthraquinone, phthalimide, tetracarboxylic diimide, naphthyl diimide, perylene diimide, succinic acid, phthalic acid, phenazine, acridine, viologen, galvinoxyl, or nitronyl nitroxide as a side chain. It is characterized by.

  The negative electrode has a substrate made of glassy carbon, pyrolytic graphite, carbon paste, carbon fiber, or indium tin oxide, or glassy carbon, pyrolytic graphite, carbon paste, carbon fiber, or indium tin oxide. It is a composite electrode composed of particles and the redox polymer.

  The main chain of the redox polymer has a cross-linked structure.

  Further, the electrolyte layer includes a potassium hydroxide aqueous solution, a sodium hydroxide aqueous solution, a calcium hydroxide aqueous solution, a sodium sulfate aqueous solution, acetonitrile, or propylene carbonate.

  The oxygen reduction catalyst is carbon fiber, carbon paste, manganese dioxide, cobalt porphyrin, platinum, ruthenium oxide, or gold.

  Furthermore, it is possible to repeatedly charge and discharge.

  Since the air battery of the present invention includes a negative electrode provided with an organic compound having an oxidation-reduction ability as an active material, it does not generate dendrite even when it is repeatedly charged and discharged, has excellent cycle characteristics, safety, and molding. Also excellent in properties. Further, the organic compound constituting the active material of the negative electrode is advantageous in that the redox potential and redox capacity can be controlled by the molecular structure, and the energy density can be set to a desired value. It has excellent additional characteristics as a battery, such as incineration, free of heavy metals, and light weight, which are inherent advantages of organic compounds.

It is a schematic diagram which shows one Example of the air battery of this invention. It is a graph showing the change of the electric potential from a negative electrode at the time of changing the charging / discharging amount of the air battery in Example 1. FIG. It is a graph showing the capacity | capacitance of each charge and discharge with respect to the frequency | count of charging / discharging when the air battery in Example 1 is charged / discharged repeatedly. 2 is a cyclic voltammogram of the air battery in Example 1. FIG. 4 is a graph of electromotive force and capacity when the discharge rate of the air battery in Example 1 is changed. It is a graph showing the change of the electric potential from a negative electrode at the time of changing the charging / discharging amount of the air battery in Example 2. FIG. It is a graph showing the change of the electric potential from a negative electrode at the time of changing the charging / discharging amount of the air battery in Example 3. FIG. It is a graph showing the capacity | capacitance of each charge and discharge with respect to the frequency | count of charging / discharging when the air battery in Example 3 is charged / discharged repeatedly. 4 is a cyclic voltammogram of an air battery in Example 3. FIG.

  Hereinafter, an embodiment of an air battery of the present invention will be described in detail with reference to the accompanying drawings.

  In FIG. 1, which is a schematic diagram showing the air battery of this example, 1 is a positive electrode provided with an oxygen reduction catalyst, and 4 is a negative electrode provided with an organic compound having oxidation-reduction ability as an active material. An electrolytic solution 5 is disposed as an electrolyte layer between the positive electrode 1 and the negative electrode 4, and a separator 7 is provided between the positive electrode 1 and the negative electrode 4 in the electrolytic solution 5. The negative electrode 4 is supported by a support electrode 6 as a substrate. The positive electrode 1, the negative electrode 4, the electrolytic solution 5, the support electrode 6, and the separator 7 are accommodated in the beaker cell container 2. An electrical load 3 is electrically connected between the positive electrode 1 and the negative electrode 4 via a switch 8.

  The organic compound used as the active material of the negative electrode 4 includes a quinone compound, an imide compound, a viologen compound, a phenazine compound, a carboxylic acid compound, or the like, or a redox polymer containing a residue having redox ability per repeating unit of the polymer. Is mentioned. The redox polymer refers to a polymer that exhibits a reversible redox reaction, that is, a reversible redox reaction.

  The redox polymer used in the present invention preferably swells with the electrolytic solution 5 and forms a gel that does not elute. By using such a redox polymer, an anion and a cation can permeate | transmit in the gel of a redox polymer, and a high performance air battery is provided.

  The redox polymer is not limited to a specific one. For example, polyolefin, polymethacrylic ester, polyacrylamide, polyamide, polyether, polyvinyl ether, polystyrene, polyphenylene sulfide, polyglycidyl ether, or these The main chain is a copolymer obtained by copolymerizing the monomers of benzoquinone, naphthoquinone, anthraquinone, phthalimide, tetracarboxylic diimide, naphthyl diimide, perylene diimide, succinic acid, phthalic acid, phenazine, acridine, viologen, What has a compound which repeats a stable redox reaction in the electrolyte solution 5 as a side chain, such as galvinoxyl or nitronyl nitroxide, can be used. The main chain of the redox polymer may have a crosslinked structure.

  Further, the negative electrode 4 can be formed by applying an active material to the support electrode 6, and as the material of the support electrode 6, glassy carbon, pyrolytic graphite, carbon paste, carbon fiber, indium tin oxide, or the like is used. Can do. Alternatively, the negative electrode 4 can be obtained by kneading and molding an active material in a particle, such as glassy carbon, pyrolytic graphite, carbon paste, carbon fiber, or indium tin oxide, without using the support electrode 6. A composite electrode prepared may be used.

  The electrolyte salt used in the electrolytic solution 5 is not limited to a specific one. For example, sodium chloride, potassium chloride, calcium chloride, iron chloride, aluminum chloride, zinc chloride, nickel chloride, sodium sulfate, sulfuric acid Examples include potassium, calcium sulfate, iron sulfate, aluminum sulfate, zinc sulfate, nickel sulfate, sodium hydroxide, potassium hydroxide, calcium hydroxide, and zinc hydroxide. Examples of the electrolyte 5 include aqueous solutions of electrolyte salts such as aqueous potassium hydroxide, aqueous sodium hydroxide, aqueous calcium hydroxide, aqueous sodium sulfate, aqueous barium hydroxide, acetonitrile, propylene carbonate, ethylene carbonate, dimethyl carbonate. Organic solvents such as methyl ethyl carbonate, γ-butyrolactone, tetrahydrofuran, dioxolane, sulfolane, dimethylformamide, dimethylacetamide, N-methyl-2-pyrrolidone can be used. Moreover, these can also be used in mixture of 2 or more types. Further, triethylamine, tetrabutylammonium hydroxide, diazabicycloundecene and the like can be added to the electrolytic solution 5 as a base.

  A solid electrolyte can also be used as the electrolyte used in the electrolytic solution 5. Polymer compounds used in the solid electrolyte include polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-ethylene copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, vinylidene fluoride- Vinylidene fluoride polymers such as hexafluoropropylene-tetrafluoroethylene terpolymer, acrylonitrile-methyl methacrylate copolymer, acrylonitrile-ethyl acrylate copolymer, acrylonitrile-methacrylic acid copolymer, acrylonitrile-vinyl acetate Examples thereof include acrylonitrile-based copolymers such as copolymers, polyethylene oxide, ethylene oxide-propylene oxide copolymers, and polymers of these acrylates and methacrylates. In addition, these polymer compounds may use what was made into the gel form containing electrolyte solution, or may use only a polymer compound as it is.

  Examples of the oxygen reduction catalyst constituting the positive electrode 1 include carbon fiber, carbon paste, granular carbon, vapor grown carbon, manganese dioxide, cobalt porphyrin, platinum, ruthenium oxide, gold, and the like. Thus, the positive electrode 1 can be configured. The material for the support electrode of the positive electrode 1 is not limited to a specific material, and examples thereof include gold, silver, carbon, and aluminum.

  The air battery can be repeatedly charged and discharged and can be used as a secondary battery.

  As described above, the air battery of the present invention is disposed between the negative electrode 4 provided with an organic compound having oxidation-reduction ability as an active material, the positive electrode 1 provided with an oxygen reduction catalyst, and the negative electrode 4 and the positive electrode 1. The electrolytic solution 5 as an electrolyte layer is provided, and since the negative electrode provided with an organic compound having an oxidation-reduction ability as an active material is provided, no dendrite is generated even when repeated charge and discharge are performed. Excellent cycle characteristics, safety and moldability. Further, the organic compound constituting the active material of the negative electrode is advantageous in that the redox potential and redox capacity can be controlled by the molecular structure, and the energy density can be set to a desired value. It has excellent additional characteristics as a battery, such as incineration, free of heavy metals, and light weight, which are inherent advantages of organic compounds.

  The structure of the air battery of the present invention is not limited to that shown in FIG. 1. For example, an electrode laminate or a wound body is made of a metal foil such as a metal case, a resin case, or an aluminum foil, and a synthetic resin film. It may be sealed with a laminate film or the like, and the shape may be a cylindrical shape, a square shape, a coin shape, a sheet shape, or the like.

  In the following examples, the air battery of the present invention will be described in detail, but the present invention is not limited to these examples.

  Poly (2-vinylanthraquinone) was synthesized as a redox polymer.

  A vinyl group was introduced from 2-bromoanthraquinone by palladium coupling to synthesize 2-vinylanthraquinone as a monomer. The obtained monomer was polymerized using azobisisobutyronitrile as an initiator in various solvents such as benzene, tetrahydrofuran and 1,2-dichloroethane to obtain poly (2-vinylanthraquinone). Poly (2-vinylanthraquinone) has a low molecular weight per charge to be discharged and is stable in a basic aqueous solution, and thus is particularly suitable for an air battery negative electrode.

  Next, the air battery shown in FIG. 1 was produced using the above redox polymer, and its performance was confirmed.

  The oxygen reduction electrode of the positive electrode 1 is obtained by adding vapor-grown carbon, manganese dioxide, and polyvinylidene fluoride in a ratio of 95: 2.5: 2.5 to a mortar, kneaded into a slurry-like carbon electrode. A coated and dried product was used. The negative electrode 4 was a composite electrode in which poly (2-vinylanthraquinone), vapor-grown carbon and polyvinylidene fluoride were mixed at a ratio of 1: 8: 1. As the electrolytic solution 5, a 30% by mass potassium hydroxide aqueous solution was used. Each member was incorporated in the beaker cell 2 to form an air battery.

  FIG. 2 shows a change in voltage when charging and discharging when a current is passed at 2 A / g of the air battery. A flat potential portion was shown at 0.82 V corresponding to the electromotive force. The obtained discharge capacity was 181 mAh / g per negative electrode active material, which was 79% of the theoretical capacity. It showed high output characteristics without large internal resistance derived from diffusion overvoltage during charging and discharging.

  Further, FIG. 3 shows a change in capacity when charging / discharging is repeated a plurality of times. Even after 500 cycles, high cycle characteristics of 89% of the initial capacity and high discharge efficiency were exhibited.

  Further, this air battery was subjected to cyclic voltammetry. As shown in FIG. 4, the obtained cyclic voltammogram showed an oxidation-reduction wave at −0.82 V.

  Further, FIG. 6 shows changes in capacity and potential when the discharge time of the air battery is changed. Even when the discharge time was changed from 10 minutes to 12 seconds, the operation was performed without any significant decrease in capacity.

  Thus, the air battery of this example showed excellent charge / discharge characteristics. In this example, since the cell type, electrolyte solution, positive electrode material, etc. are not optimized, the air battery of the present invention remains in a beaker cell, but by optimizing them, it can be changed into a coin cell and a cylindrical cell. It is also possible to do.

  An air battery was produced in the same manner as in Example 1 except that 30% by mass aqueous sodium hydroxide solution was used instead of 30% by mass potassium hydroxide in the electrolytic solution 5. FIG. 5 shows voltage changes when charging and discharging are performed.

  A poly (decylviologen) -poly (4-styrenesulfonic acid) complex was synthesized as a redox polymer.

  To a 50 ml snap vial, 10 ml of a 0.2 M aqueous solution of poly (4-styrenesulfonic acid) and 10 ml of a 0.1 M aqueous solution of polydecylviologen were added and stirred. After stirring, a pale yellow precipitate was deposited. This was filtered through a glass filter and dried to obtain a poly (decylviologen) -poly (4-styrenesulfonic acid) complex.

  Next, the air battery shown in FIG. 1 was produced using the above redox polymer, and its performance was confirmed.

  The oxygen reduction electrode of the positive electrode 1 is obtained by adding vapor-grown carbon, manganese dioxide, and polyvinylidene fluoride in a ratio of 95: 2.5: 2.5 to a mortar, kneaded into a slurry-like carbon electrode. A coated and dried product was used. The negative electrode 4 was a composite electrode in which a poly (decylviologen) / poly (4-styrenesulfonic acid) complex, vapor-grown carbon, and polyvinylidene fluoride were mixed at a ratio of 1: 8: 1. Each member was incorporated in a beaker cell to form an air battery.

  FIG. 7 shows changes in voltage when charging and discharging are performed when current is supplied at 0.2 A / g of the air battery. A flat potential portion was shown at 0.4 V corresponding to the electromotive force. The obtained discharge capacity was 32 mAh / g per negative electrode active material, which was 44% of the theoretical capacity.

  Further, FIG. 8 shows a change in capacity when charging / discharging is repeated a plurality of times. Even after 20 cycles, the cycle characteristics were as high as 91% of the initial capacity.

  Further, this air battery was subjected to cyclic voltammetry. As shown in FIG. 9, the obtained cyclic volta also showed an oxidation-reduction wave at 0.63 V in grams.

1 Positive electrode 4 Negative electrode 5 Electrolytic solution (electrolyte layer)

Claims (10)

An air battery comprising: a negative electrode provided with an organic compound having oxidation-reduction ability as an active material; a positive electrode provided with an oxygen reduction catalyst; and an electrolyte layer disposed between the negative electrode and the positive electrode. The air battery according to claim 1, wherein the organic compound is a quinone compound, an imide compound, a viologen compound, a phenazine compound, or a carboxylic acid compound. 2. The air battery according to claim 1, wherein the organic compound is a redox polymer containing a residue having redox ability per repeating unit of the polymer. The air according to claim 3, wherein the redox polymer has a main chain of polyolefin, polymethacrylic ester, polyacrylamide, polyamide, polyether, polyvinyl ether, polystyrene, polyphenylene sulfide, or a copolymer thereof. battery. The redox polymer has benzoquinone, naphthoquinone, anthraquinone, phthalimide, tetracarboxylic diimide, naphthyl diimide, perylene diimide, succinic acid, phthalic acid, phenazine, acridine, viologen, galvinoxyl, or nitronyl nitroxide as a side chain. The air battery according to claim 3 or 4. The negative electrode has a substrate made of glassy carbon, pyrolytic graphite, carbon paste, carbon fiber, or indium tin oxide, or glassy carbon, pyrolytic graphite, carbon paste, carbon fiber, or particles of indium tin oxide. The air battery according to any one of claims 3 to 5, wherein the air battery is a composite electrode made of the redox polymer. The air battery according to any one of claims 3 to 6, wherein the main chain of the redox polymer has a crosslinked structure. The air battery according to claim 1, wherein the electrolyte layer contains an aqueous potassium hydroxide solution, an aqueous sodium hydroxide solution, an aqueous calcium hydroxide solution, an aqueous sodium sulfate solution, acetonitrile, or propylene carbonate. . The air battery according to any one of claims 1 to 8, wherein the oxygen reduction catalyst is carbon fiber, carbon paste, manganese dioxide, cobalt porphyrin, platinum, ruthenium oxide, or gold. The air battery according to any one of claims 1 to 9, wherein the air battery can be repeatedly charged and discharged.

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