JP2013037999A - Metal-air battery - Google Patents

Abstract

A metal-air battery excellent in volumetric efficiency and energy density is provided.
An air electrode having an air electrode layer containing oxygen as an active material, a negative electrode having a negative electrode layer containing a negative electrode active material, and a metal ion conducting between the air electrode layer and the negative electrode layer. An electrolyte layer serving as a metal-air battery includes a laminated power generation element, and a flexible outer body formed of a flexible film that accommodates the power generation element, and the air electrode includes the electrolyte The air electrode layer and the air electrode current collector having a conductive and porous structure are sequentially stacked from the layer side, and the flexible outer package communicates with the air electrode current collector. The power generating element is pressurized at a pressure equal to or higher than normal pressure in the stacking direction by an oxygen-containing gas that supplies oxygen to the oxygen uptake hole from the outside of the flexible exterior body. A metal-air battery characterized by the above.
[Selection] Figure 1

Description

  The present invention relates to a metal-air battery.

A metal-air battery using oxygen as a positive electrode active material has advantages such as high energy density, easy size reduction and weight reduction. Therefore, it is attracting attention as a high-capacity battery that exceeds the lithium secondary battery that is currently widely used. As metal-air batteries, for example, lithium-air batteries, magnesium-air batteries, zinc-air batteries, and the like are known.
The metal-air battery can be charged and discharged by performing an oxidation-reduction reaction of oxygen at the air electrode and an oxidation-reduction reaction of a metal of a conductive ion species at the negative electrode. For example, in a metal air battery (secondary battery) in which conductive ions are monovalent metal ions, the following charge / discharge reaction is considered to proceed. In the following formula, M represents a metal species.

[During discharge]
Negative electrode: M → M ⁺ + e ⁻
Positive electrode: 2M ⁺ + O ₂ + 2e ⁻ → M ₂ O ₂
[When charging]
Negative electrode: M ⁺ + e ⁻ → M
Positive electrode: M ₂ O ₂ → 2M ⁺ + O ₂ + 2e ⁻

The metal-air battery includes, for example, an air electrode layer containing a conductive material and a binder, an air electrode current collector that collects the air electrode layer, and a negative electrode containing a negative electrode active material (metal, alloy, etc.) A power generation element having a layer, a negative electrode current collector for collecting current of the negative electrode layer, and an electrolyte layer interposed between the air electrode layer and the negative electrode layer.
Specific metal-air batteries include those disclosed in Patent Documents 1 to 3, for example.

International Publication WO2010 / 100749 JP 2010-244929 A JP 2005-116235 A

In metal-air batteries, downsizing is an important technical issue, and improvement in volumetric efficiency is required. In particular, in order to obtain a larger current value, when connecting a plurality of single cells, an oxygen supply path for supplying oxygen to each power generating element and, if necessary, ensuring insulation between the single cells. It is necessary to provide an insulating member or the like, and volume efficiency and energy density are desired to be improved.
However, a conventional metal-air battery such as Patent Document 1 does not provide sufficient volume efficiency and energy density.

  The present invention has been accomplished in view of the above circumstances, and an object of the present invention is to provide a metal-air battery excellent in volumetric efficiency and energy density.

The metal-air battery of the present invention is disposed between an air electrode having an air electrode layer containing oxygen as an active material, a negative electrode having a negative electrode layer containing a negative electrode active material, and the air electrode layer and the negative electrode layer, A metal-air battery comprising an electrolyte layer responsible for ion conduction and a laminated power generation element, and a flexible exterior body formed of a flexible film that accommodates the power generation element,
The air electrode has a structure in which the air electrode layer and an air electrode current collector having a conductive and porous structure are sequentially stacked from the electrolyte layer side,
The flexible exterior body has an oxygen uptake hole communicating with the air electrode current collector,
The power generation element is pressurized from the outside of the flexible exterior body at a pressure equal to or higher than normal pressure in the stacking direction by an oxygen-containing gas that supplies oxygen to the oxygen intake hole.

  In the metal-air battery of the present invention, the power generation element is pressurized in the stacking direction by an oxygen-containing gas for supplying oxygen to the air electrode from the outside of the flexible exterior body that houses the power generation element. In addition, oxygen is supplied to the air electrode layer through the air electrode current collector that has a porous structure and also functions as an oxygen flow path. As described above, according to the present invention, the power generation element is restrained by the oxygen-containing gas for supplying oxygen to the air electrode layer, and the air electrode current collector also serves as a flow path for oxygen gas. A metal-air battery with high efficiency and energy density can be provided. In particular, when two or more power generating elements are stacked and connected in series, the effect of improving the volume efficiency and energy density of the metal-air battery is excellent. In addition, since the power generation element is restrained by the oxygen-containing gas as described above, a uniform surface pressure can be applied to the power generation element, and a uniform oxygen supply to the air electrode layer by the air electrode current collector is possible. Therefore, the metal-air battery of the present invention is excellent in durability and power generation efficiency.

As a form of the air electrode current collector, for example, an outer peripheral edge of a surface orthogonal to the stacking direction of the power generation element is from an outer peripheral edge of a surface orthogonal to the stacking direction of the air electrode layer, the electrolyte layer, and the negative electrode. The thing which has the extended part extended is mentioned. By the extended portion, a flow path of the oxygen-containing gas in the stacking direction can be formed in the flexible exterior body.
As a specific aspect of the form including the flow path of the oxygen-containing gas as described above, for example, the air electrode current collector has the outer peripheral edge of the orthogonal plane, the air electrode layer, the electrolyte layer, and the negative electrode. The air electrode current collector, the air electrode layer, the electrolyte layer, and the negative electrode are stacked by overlapping the center points of the orthogonal surfaces. And the aspect in which the said extension part surrounds the outer periphery of the said air electrode layer, the said electrolyte layer, and the said negative electrode is mentioned.

  The extending portion may have a form in which at least a surface is covered with an insulating material. With such a configuration, it is possible to prevent the electrode reaction from progressing in the extending portion that functions as a flow path for the oxygen-containing gas. The progress of the electrode reaction in the extending part may cause demerits such as blocking of the extending part that becomes the flow path of the oxygen-containing gas.

The metal-air battery of the present invention may include two or more power generation elements. Specifically, two or more power generation elements are stacked and connected in series, and the porous structure is blocked in a region where the air electrode current collector adjacent to the negative electrode layer is in contact with the negative electrode layer. The form which is doing is mentioned.
In the form as described above, the reaction between the material constituting the negative electrode layer adjacent to the air electrode current collector and oxygen is suppressed, and between the two power generation elements stacked, from one power generation element to the other. The oxygen-containing gas can efficiently flow to the power generation element.

  The metal-air battery of the present invention is excellent in volumetric efficiency and energy density. Further, the metal-air battery of the present invention is capable of uniform oxygen supply to the air electrode layer and uniform pressurization of the power generation element because the power generation element is constrained by the oxygen-containing gas. Excellent durability.

It is a cross-sectional schematic diagram which shows one example of a metal air battery of this invention. It is a cross-sectional schematic diagram which shows one example of the air electrode electrical power collector in the metal air battery of this invention.

The metal-air battery of the present invention is disposed between an air electrode having an air electrode layer containing oxygen as an active material, a negative electrode having a negative electrode layer containing a negative electrode active material, and the air electrode layer and the negative electrode layer, A metal-air battery comprising an electrolyte layer responsible for ion conduction and a laminated power generation element, and a flexible exterior body formed of a flexible film that accommodates the power generation element,
The air electrode has a structure in which the air electrode layer and an air electrode current collector having a conductive and porous structure are sequentially stacked from the electrolyte layer side,
The flexible exterior body has an oxygen uptake hole communicating with the air electrode current collector,
The power generation element is pressurized from the outside of the flexible exterior body at a pressure equal to or higher than normal pressure in the stacking direction by an oxygen-containing gas that supplies oxygen to the oxygen intake hole.

Hereinafter, the metal-air battery of the present invention will be described with reference to FIG.
In FIG. 1, a metal-air battery 100 includes a power generation element 6 in which an air electrode (positive electrode) 1, a negative electrode 4, and an electrolyte layer 5 disposed between the air electrode 1 and the negative electrode 4 are laminated. . The air electrode 1 has a structure in which an air electrode layer 2 using oxygen as an active material and an air electrode current collector 3 that collects current from the air electrode layer 2 are stacked in this order from the electrolyte layer 5 side. 4 consists of a negative electrode layer containing a negative electrode active material. That is, the power generation element 6 has a structure in which the air electrode current collector 3, the air electrode layer 2, the electrolyte layer 5, and the negative electrode (negative electrode layer) 4 are sequentially stacked.
In the air electrode current collector 3, the outer peripheral edge of the surface orthogonal to the stacking direction of the power generation element 6 is orthogonal to the stacking direction of the air electrode layer 2, the electrolyte layer 5, and the negative electrode 4 (stacking direction of the power generation element 6). It has the extension part 3A extended from the outer periphery of a surface.

The metal-air battery 100 in FIG. 1 includes two power generation elements 6 (6A, 6B) stacked as described above, and forms the interface between the two power generation elements, and the negative electrode 4 of the power generation element 6A and the power generation element 6B. These air generating elements 6A and 6B are connected in series by contact with the air electrode current collector 3.
The space 9 sandwiched between the extending portions 3A of the two air electrode current collectors 3 constituting the two power generation elements functions as a gas flow path, and the air electrode current collector 3 and the air electrode layer 2 of the power generation element 6A. From this, the oxygen-containing gas can circulate to the extending portion 3A of the air electrode current collector 3 of the power generation element 6B.
Further, similarly to the air electrode current collector 3, the negative electrode 4 of the power generation element 6B is provided with a conductive porous body 10 having a conductive and porous structure and extending 10A adjacent thereto, A space 9 sandwiched between the extension 3A of the air electrode current collector 3 of the power generation element 6B and the extension 10A of the conductive porous body 10 functions as a gas flow path, and the air electrode layer 3 of the power generation element 6B. The unreacted portion of the oxygen-containing gas supplied to the gas can flow to the conductive porous body 10. The flexible exterior body 7 may be provided with a discharge port that communicates with the exterior of the flexible exterior body 7 and can discharge unreacted oxygen-containing gas from the conductive porous body 10 (see FIG. Not shown).

  These power generation elements 6 are accommodated in a flexible exterior body 7 formed of a flexible film, and pressurized from the outside of the flexible exterior body 7 in the stacking direction by an oxygen-containing gas 11. It is restrained. The flexible exterior body 7 is provided with an oxygen uptake hole 8 communicating with the air electrode current collector 3, and an oxygen-containing gas 11 is taken into the flexible exterior body 7 from the oxygen uptake hole 8, It is supplied to the air electrode layer 2.

  The metal-air battery 100 is further connected to the air electrode current collector 3 of the power generation element 6A, the positive electrode terminal 12 extending to the outside of the flexible exterior body 7, and the conductive porous adjacent to the negative electrode of the power generation element 6B. It has a negative electrode terminal 13 connected to the body 10 and extending to the outside of the flexible exterior body 7.

  In the metal-air battery of the present invention, first, the power generation element is pressurized in the stacking direction with a gas having a pressure equal to or higher than normal pressure from the outside of the flexible exterior body that houses the power generation element. Thus, since the power generation element is restrained by the gas, the pressure applied to the power generation element becomes uniform, so compared to the case where a high pressure is locally applied by using a restraining member, etc. The life of the members constituting the power generation element can be extended, and the durability of the metal-air battery can be improved. More specifically, for example, it is possible to suppress deterioration of the battery member due to oxygen shortage and cycle deterioration due to non-uniform precipitation of precipitates generated during discharge.

  In addition, in the present invention, the gas that restrains the power generation element is an oxygen-containing gas that contains oxygen as an active material of the air electrode, and restrains the power generation element and also supplies oxygen to the air electrode. The number of constituent members can be reduced, and the metal-air battery can be downsized.

  Furthermore, the oxygen-containing gas enters the inside of the flexible exterior body from the oxygen intake hole of the flexible exterior body, passes through the air electrode current collector having a porous structure, and enters the air electrode layer. Supply. That is, since the air electrode current collector also functions as a flow path for the oxygen-containing gas, it is possible to supply oxygen to the air electrode layer without providing a rib or the like that becomes a flow path for the oxygen-containing gas. . As a result, the metal-air battery can be further reduced in size.

  In particular, as shown in FIG. 1, when two or more power generation elements are stacked and connected in series, the air electrode current collector having a porous structure also functions as an oxygen gas flow path between adjacent power generation elements. However, the miniaturization effect is particularly high.

  In the present invention, the metal-air battery is not particularly limited as long as it uses oxygen as the positive electrode active material and the conductive ions are metal ions, and may be a primary battery or a secondary battery. . Specific examples of the metal-air battery include a lithium-air battery, a sodium-air battery, a potassium-air battery, a magnesium-air battery, a calcium-air battery, a zinc-air battery, an aluminum-air battery, and an iron-air battery.

Hereafter, each structure of the metal air battery of this invention is demonstrated in detail.
[Power generation element]
The power generation element has a structure in which an air electrode, an electrolyte layer, and a negative electrode are laminated in this order. In the present invention, the “stacking direction of the power generation element” means the stacking direction of the air electrode, the electrolyte layer, and the negative electrode constituting the power generation element (see FIG. 1).
(Air electrode)
The air electrode includes an air electrode layer including at least a conductive material, and an air electrode current collector that collects current from the air electrode layer. In the air electrode, the air electrode layer and the air electrode current collector are laminated in the order of the air electrode layer and the current collector from the electrolyte layer side.

<Air electrode layer>
The air electrode layer is a reaction field between supplied oxygen and metal ions, and the reaction between oxygen and metal ions (generation and decomposition of metal oxides, metal hydroxides, etc.) occurs on the surface of the conductive material. The air electrode layer usually has a porous structure and ensures the diffusibility of oxygen as an active material.

The conductive material is not particularly limited as long as it has conductivity, and examples thereof include a conductive carbon material.
The conductive carbon material is not particularly limited, but a carbon material having a high specific surface area is preferable from the viewpoint of the reaction field area and space in the air electrode. Specifically, the conductive carbon material preferably has a specific surface area of 10 m ² / g or more, particularly 100 m ² / g or more, and more preferably 600 m ² / g or more. Specific examples of the conductive carbon material having a high specific surface area include carbon black, activated carbon, carbon carbon fiber (for example, carbon nanotube, carbon nanofiber, etc.). Here, the specific surface area of the conductive material can be measured by, for example, the BET method based on nitrogen adsorption measurement.
The conductive carbon material may or may not have a porous structure, but from the viewpoint of securing a reaction field space, a conductive carbon material preferably has a porous structure, and particularly has a high pore of 1 cc / g or more. Those having a volume are preferred. Specific examples of the conductive carbon material having a high pore volume include carbon black, activated carbon, carbon carbon fiber (for example, carbon nanotube, carbon nanofiber, etc.) and the like. Here, the pore volume of the conductive material can be measured by, for example, the BJH method based on nitrogen adsorption measurement.
The content of the conductive material in the air electrode layer is preferably in the range of 10% by weight to 99% by weight, for example, although it depends on the density, specific surface area, and the like.

The air electrode layer may contain an air electrode catalyst that promotes the reaction of oxygen in the air electrode. Such an air electrode catalyst may be supported on the conductive material.
The air electrode catalyst is not particularly limited. For example, phthalocyanine compounds such as cobalt phthalocyanine, manganese phthalocyanine, nickel phthalocyanine, tin phthalocyanine oxide, titanium phthalocyanine, and dilithium phthalocyanine; naphthocyanine compounds such as cobalt naphthocyanine; iron porphyrin Organic materials such as porphyrin-based compounds such as MnO ₂ , CeO ₂ , Co ₃ O ₄ , NiO, V ₂ O ₅ , Fe ₂ O ₃ , ZnO, CuO, LiMnO ₂ , Li ₂ MnO ₃ , LiMn ₂ O _{4 , Li 4 Ti 5 O 12,} Li 2 TiO 3, LiNi 1/3 Co 1/3 Mn 1/3 O 2, LiNiO 2, LiVO 3, Li 5 FeO 4, LiFeO 2, LiCrO 2, LiCoO 2, LiCuO 2 , Li _{nO 2, Li 2 MoO 4,} LiNbO 3, LiTaO 3, Li 2 WO 4, Li 2 ZrO 3, NaMnO 2, CaMnO 3, CaFeO 3, MgTiO 3, KMnO metal oxides such as _2; Au, Pt, Ag, etc. Inorganic materials such as noble metals. Moreover, the composite_body | complex which combined two or more of the said material can also be used as an air electrode catalyst.
The content of the air electrode catalyst in the air electrode layer is preferably in the range of 1% by weight to 90% by weight, for example.

The air electrode layer preferably further contains a binder from the viewpoint of fixing the conductive material and the air electrode catalyst.
Examples of the binder include polyvinylidene fluoride (PVDF), a copolymer of PVDF and hexafluoropropylene (HFP), polytetrafluoroethylene (PTFE), styrene butadiene rubber (SBR), and the like.
The binder content in the air electrode layer is preferably in the range of, for example, 1% by weight to 40% by weight.

  The thickness of the air electrode layer varies depending on the use of the metal-air battery, but is preferably in the range of 2 μm to 500 μm, particularly in the range of 5 μm to 300 μm.

<Air current collector>
The air electrode current collector performs current collection of the air electrode layer, and in the present invention, a material having a porous structure in addition to conductivity is used.
The air electrode current collector is not particularly limited as long as it has a desired conductivity (electron conductivity) and has a porous structure through which an oxygen-containing gas can flow.

  Examples of the material for the air electrode current collector include metal materials such as stainless steel, nickel, aluminum, iron, titanium, and copper, carbon materials such as carbon fiber and carbon paper, and high electron conductive ceramic materials such as titanium nitride. Can be mentioned.

Examples of the porous structure include a mesh structure in which constituent fibers are regularly arranged, a nonwoven fabric structure in which constituent fibers are randomly arranged, and a three-dimensional network structure having independent holes and connecting holes.
The porous structure of the air electrode current collector may be uniform or non-uniform throughout the air electrode current collector. For example, it may have a porosity distribution in which the porosity (porosity) varies in the thickness direction of the air electrode current collector (the same as the stacking direction of the power generation elements). In addition, the porosity is a ratio of the volume of the pore portion to the volume of the entire porous body.
Specifically, when two or more power generation elements are stacked and connected in series, the air electrode current collector adjacent to the negative electrode layer of the power generation elements connected in series is porous in the region in contact with the negative electrode layer. The structure is preferably occluded. As described above, since the porous structure in the region in contact with the negative electrode layer is blocked, it is possible to prevent the material constituting the negative electrode layer from contacting and reacting with a gas containing oxygen and degrading the performance. It is also effective to form a flow of oxygen-containing gas such that the oxygen-containing gas efficiently flows to the air electrode layer where oxygen is required.
When the region in contact with the negative electrode layer is closed as described above, for example, as shown in FIG. 2, the conductive non-porous body 3a, the conductive porous body 3b, and the conductive porous are sequentially formed from the adjacent negative electrode layer 4 side. It is also effective to use a laminate of the material bodies 3c as the air electrode current collector 3. Here, since the conductive non-porous body 3a is a region in contact with the negative electrode layer, the conductive non-porous body 3a is a conductor that does not have a porous structure, and the conductive porous body 3b is more than the conductive porous body 3c. The porosity is low. The air electrode current collector having such a multilayer structure can be produced, for example, by press-molding the conductive non-porous body 3a and the conductive porous bodies 3b and 3c having different porosity.
Incidentally, the air electrode current collector having a porosity distribution has a continuous porosity as well as a form in which the porosity changes stepwise as shown in the multilayer air electrode current collector shown in FIG. It may be a changing form.
Moreover, the electroconductive member which contacts a negative electrode layer including the electroconductive nonporous body adjacent to the said negative electrode layer can also be regarded as a collector of a negative electrode layer.

The shape of the air electrode current collector is not particularly limited and can be appropriately selected.
From the viewpoint of the flow of oxygen-containing gas in the flexible exterior body, particularly the flow of oxygen-containing gas in the flexible exterior body when two or more power generation elements are stacked, the air electrode current collector has the following shape: It is preferable to have. That is, it is preferable that the outer peripheral edge of the surface orthogonal to the stacking direction of the power generation element has an extending portion that extends from the outer peripheral edge of the air electrode layer, the electrolyte layer, and the negative electrode (negative electrode layer). Such an extended portion functions as a flow path for the oxygen-containing gas when the air electrode current collector is laminated with the air electrode layer, the electrolyte layer, and the negative electrode (negative electrode layer), and the flexible exterior body The flow of oxygen-containing gas in the stacking direction of the power generation elements can be formed.
The specific form of the extending portion is not particularly limited, and may be selected as appropriate. For example, an air electrode current collector in which the outer periphery of the orthogonal surface has a size and shape that is slightly larger than the outer peripheral edge of the air electrode layer, the electrolyte layer, and the negative electrode. In such an air electrode current collector, when the air electrode layer, the electrolyte layer, and the negative electrode are stacked with the center point of the orthogonal plane superimposed, so as to surround the outer periphery of the air electrode layer, the electrolyte layer, and the negative electrode, An extension part will be provided.

It is preferable that at least the surface of the extended portion of the air electrode current collector is covered with an insulating material. If it has electrical conductivity, it functions as a reaction field for the air electrode, which may cause the porous structure to be clogged by precipitates generated during discharge, or change (increase / decrease) in the reaction area. This is because there is a possibility that current density variation between the cells may occur.
In other words, the extending portion only needs to be permeable to the oxygen-containing gas, and may be formed of an insulating material different from the region in contact with the air electrode layer or the negative electrode, but the manufacturing process is complicated. In view of the above, it can be said that it is preferable to selectively insulate the surface of the region to be the extended portion of the conductive porous body. The insulating treatment method is not particularly limited as long as the oxygen-containing gas permeability of the extending portion can be ensured, and examples thereof include application of an insulating material such as polytetrafluoroethylene.

  Although the thickness of an air electrode electrical power collector is not specifically limited, For example, it is preferable that it is the range of 10 micrometers-1000 micrometers.

The method for producing the air electrode is not particularly limited. For example, an air electrode can be formed using an air electrode material obtained by mixing a conductive material and other air electrode layer constituent materials such as a binder. Specifically, an air electrode material containing a solvent is rolled or coated on the surface of the air electrode current collector and formed, and if necessary, air treatment is performed by performing a drying treatment, a pressure treatment, a heat treatment, or the like. An air electrode in which an electrode layer and an air electrode current collector are stacked can be produced. Alternatively, an air electrode material containing a solvent is rolled or applied and molded, and if necessary, an air electrode layer that has been subjected to a drying treatment, a pressure treatment, a heat treatment, or the like is overlaid with an air electrode current collector. By performing pressurization or heating, an air electrode in which an air electrode layer and an air electrode current collector are laminated can be produced.
The solvent used for the air electrode material is not particularly limited as long as it has volatility, and can be appropriately selected. Specific examples include acetone, N, N-dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP) and the like. A solvent having a boiling point of 200 ° C. or lower is preferable because the air electrode material can be easily dried.
The method for applying the air electrode material is not particularly limited, and general methods such as a doctor blade method, an ink jet method, and a spray method can be used.

(Electrolyte layer)
The electrolyte is not particularly limited as long as it can conduct metal ions between the air electrode and the negative electrode, and may be an electrolytic solution or a solid electrolyte. However, when the electrolytic solution is used, leakage occurs due to the restraining pressure of the oxygen-containing gas. It is preferable to use a solid electrolyte because there is a possibility that a voltage drop will occur.
As the solid electrolyte, for example, a gelled electrolyte, a solid inorganic electrolyte, a solid organic electrolyte, or the like can be used. Examples of the gelation method of the non-aqueous electrolyte include, for example, polymers such as polyethylene oxide (PEO), polyacrylonitrile (PAN), polyvinylidene fluoride (PVDF), and polymethyl methacrylate (PMMA). The method of adding is mentioned.

Examples of the electrolytic solution include a non-aqueous electrolytic solution and an aqueous electrolytic solution. The nonaqueous electrolytic solution contains a supporting electrolyte salt and a nonaqueous solvent.
The non-aqueous solvent is not particularly limited. For example, propylene carbonate (PC), ethylene carbonate (EC), vinylene carbonate, dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), methyl propyl carbonate. , Isopropiomethyl carbonate, ethyl propionate, methyl propionate, γ-butyrolactone, ethyl acetate, methyl acetate, tetrahydrofuran, 2-methyltetrahydrofuran, ethylene glycol dimethyl ether, ethylene glycol didiethyl ether, acetonitrile (AcN), dimethyl sulfoxide (DMSO) ), Diethoxyethane, dimethoxyethane (DME), tetraethylene glycol dimethyl ether (TEGDME) and the like. .

Moreover, an ionic liquid can also be used as a non-aqueous solvent. Examples of the ionic liquid include N, N, N-trimethyl-N-propylammonium bis (trifluoromethanesulfonyl) amide [abbreviation: TMPA-TFSA], N-methyl-N-propylpiperidinium bis (trifluoromethanesulfonyl). ) Amide [abbreviation: PP13-TFSA], N-methyl-N-propylpyrrolidinium bis (trifluoromethanesulfonyl) amide [abbreviation: P13-TFSA], N-methyl-N-butylpyrrolidinium bis (trifluoromethanesulfonyl) ) Aliphatic quaternary ammonium such as amide [abbreviation: P14-TFSA], N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium bis (trifluoromethanesulfonyl) amide [abbreviation: DEME-TFSA] Salt; 1-methyl-3-ethyl ester Dazo tetrafluoroborate [abbreviation: EMIBF _4], 1- methyl-3-ethyl imidazolium bis (trifluoromethanesulfonyl) amide [abbreviation: EMITFSA], 1- allyl-3-ethyl imidazolium bromide [abbreviation: AEImBr], 1-allyl-3-ethylimidazolium tetrafluoroborate [abbreviation: AEImBF ₄ ], 1-allyl-3-ethylimidazolium bis (trifluoromethanesulfonyl) amide [abbreviation: AEImTFSA], 1,3-diallylimidazolium bromide [abbreviation: AAImBr], 1,3- diallyl tetrafluoroborate _{[abbreviation:} AAImBF 4], 1,3- diallyl imidazolium bis (trifluoromethanesulfonyl) amide [abbreviation: AAImTFSA] Include alkyl imidazolium quaternary salt of.

  From the viewpoint of electrochemical stability against oxygen radicals, AcN, DMSO, DME, PP13-TFSA, P13-TFSA, P14-TFSA, TMPA-TFSA, DEME-TFSA and the like are preferable as the nonaqueous solvent.

The supporting electrolyte salt only needs to have solubility in a non-aqueous solvent and express desired metal ion conductivity. Usually, a metal salt containing a metal ion to be conducted can be used. For example, in the case of a lithium air battery, a lithium salt can be used as the supporting electrolyte salt. Examples of the lithium salt include inorganic lithium salts such as LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAsF ₆ , LiOH, LiCl, LiNO ₃ , Li ₂ SO ₄ . In addition, CH ₃ CO ₂ Li, lithium bisoxalate borate (abbreviation LiBOB), LiN (CF ₃ SO ₂ ) ₂ (abbreviation LiTFSA), LiN (C ₂ F ₅ SO ₂ ) ₂ (abbreviation LiBETA), LiN (CF ₃ An organic lithium salt such as (SO ₂ ) (C ₄ F ₉ SO ₂ ) can also be used.
In the non-aqueous electrolyte, the content of the supporting electrolyte salt with respect to the non-aqueous solvent is not particularly limited. For example, the concentration of the lithium salt in the non-aqueous electrolyte is, for example, in the range of 0.5 mol / L to 3 mol / L. .

The aqueous electrolyte contains a supporting electrolyte salt and water. The supporting electrolyte salt is not particularly limited as long as it has solubility in water and expresses desired ionic conductivity. Usually, a metal salt containing a metal ion to be conducted can be used. For example, in the case of a lithium air battery, for example, a lithium salt such as LiOH, LiCl, LiNO ₃ , Li ₂ SO ₄ , or CH ₃ COOLi can be used.

  When the electrolytic solution is used after being gelled, for example, after mixing the polymer and the electrolytic solution as described above, the mixed solution is cast-coated on the substrate, dried, peeled off from the substrate, and then cut. Thus, a gel electrolyte membrane can be produced.

Examples of the solid electrolyte include inorganic solid electrolytes. The inorganic solid electrolyte may be glass, crystal, or glass ceramic. When these solid electrolytes are used, for example, the solid electrolyte layer can be produced by rolling the solid electrolyte or applying and drying a slurry in which the solid electrolyte is mixed with a solvent.
What is necessary is just to select a specific inorganic solid electrolyte suitably according to a conductive metal ion.
For example, in the case of a lithium-air battery, as the NASICON type oxide, for example, Li _{a Xb} Y _{cP d} O _e (X is from B, Al, Ga, In, C, Si, Ge, Sn, Sb and Se) Y is at least one selected from the group consisting of Ti, Zr, Ge, In, Ga, Sn and Al, and a to e are 0.5 <a <5.0, 0 ≦ b <2.98, 0.5 ≦ c <3.0, 0.02 <d ≦ 3.0, 2.0 <b + d <4.0, 3.0 <e ≦ 12 0). In particular, in the above formula, an oxide where X = Al and Y = Ti (Li-Al-Ti-PO-based NASICON type oxide), and X = Al, Y = Ge or X = Ge, Y = An oxide that is Al (Li—Al—Ge—Ti—O-based NASICON-type oxide) is preferable.
As the perovskite-type oxide, for _example, oxide represented by Li _{x La 1-x} TiO _3, etc. (Li-La-TiO perovskite oxide) can be exemplified.

In the case of a lithium-air battery, as the LISICON-type oxide, for example, Li ₄ XO ₄ -Li ₃ YO ₄ (X is at least one selected from Si, Ge, and Ti, and Y is P, As, and Li ₄ XO ₄ —Li ₂ AO ₄ (X is at least one selected from Si, Ge, and Ti, and A is at least one selected from Mo and S). Li ₄ XO ₄ —Li ₂ ZO ₂ (X is at least one selected from Si, Ge, and Ti, Z is at least one selected from Al, Ga, and Cr), and Li ₄ XO ₄ —Li ₂ BXO ₄ (X is at least one selected from Si, Ge, and Ti, and B is at least one selected from Ca and Zn), Li ₃ DO ₃ —Li ₃ YO ₄ (D is B, Y is at least one selected from P, As and V). In particular, Li ₄ SiO ₄ —Li ₃ PO ₄ , Li ₃ BO ₃ —Li ₃ PO _{4, and the} like are preferable.

In the case of a lithium-air battery, examples of the garnet-type oxide include an oxide represented by Li _{3 + x} A _y G _z M _{2 -v} B _v O ₁₂ . Here, A, G, M and B are metal cations. A is preferably an alkaline earth metal cation such as Ca, Sr, Ba and Mg, or a transition metal cation such as Zn. G is preferably a transition metal cation such as La, Y, Pr, Nd, Sm, Lu, or Eu. Examples of M include transition metal cations such as Zr, Nb, Ta, Bi, Te, and Sb. Among these, Zr is preferable. B is preferably In, for example. x preferably satisfies 0 ≦ x ≦ 5, and more preferably satisfies 4 ≦ x ≦ 5. y preferably satisfies 0 ≦ y ≦ 3, and more preferably satisfies 0 ≦ y ≦ 2. z preferably satisfies 0 ≦ z ≦ 3, and more preferably satisfies 1 ≦ z ≦ 3. v preferably satisfies 0 ≦ v ≦ 2, and more preferably satisfies 0 ≦ v ≦ 1. O may be partially or completely exchanged with a divalent anion and / or a trivalent anion, for example, N ³⁻ . As the garnet-type oxide, Li—La—Zr—O-based oxides such as Li ₇ La ₃ Zr ₂ O ₁₂ are preferable.

(Negative electrode)
The negative electrode includes a negative electrode layer containing a negative electrode active material capable of releasing and incorporating metal ion species. In addition to the negative electrode layer, the negative electrode may include a negative electrode current collector that collects current from the negative electrode layer.
The negative electrode active material is not particularly limited as long as it can release and incorporate metal ion species, and examples thereof include simple metals, alloys, metal oxides, metal sulfides, and metal nitrides containing metal ions. Can be mentioned. A carbon material can also be used as the negative electrode active material. As the negative electrode active material, a single metal or an alloy is preferable, and a single metal is particularly preferable. Examples of the single metal of the negative electrode active material include lithium, sodium, potassium, magnesium, calcium, aluminum, zinc, and iron. Examples of the alloy include alloys containing at least one of these single metals.
More specifically, examples of the negative electrode active material of the lithium-air battery include metal lithium; lithium alloys such as lithium aluminum alloy, lithium tin alloy, lithium lead alloy, and lithium silicon alloy; tin oxide, silicon oxide, and lithium titanium. Metal oxides such as oxides, niobium oxides and tungsten oxides; metal sulfides such as tin sulfides and titanium sulfides; metal nitrides such as lithium cobalt nitrides, lithium iron nitrides and lithium manganese nitrides; and Examples thereof include carbon materials such as graphite, among which metal lithium and carbon materials are preferable, and metal lithium is more preferable from the viewpoint of increasing capacity.

  Although the negative electrode layer should just contain a negative electrode active material at least, it may contain the binder which fixes a negative electrode active material as needed. For example, when a foil-like metal or alloy is used as the negative electrode active material, the negative electrode layer can be configured to contain only the negative electrode active material, but when a powdered negative electrode active material is used, the negative electrode layer Can be made into a form containing a negative electrode active material and a binder. The negative electrode layer may contain a conductive material. Since the types and amounts of use of the binder and the conductive material are the same as those of the above-described air electrode layer, description thereof is omitted here.

The material of the negative electrode current collector is not particularly limited as long as it has conductivity. For example, stainless steel, nickel, etc. are mentioned. Examples of the shape of the negative electrode current collector include a foil shape, a plate shape, and a mesh shape. Further, the battery case may have a function as a negative electrode current collector.
As shown in FIG. 1, when two or more power generation elements are stacked and connected in series, the negative electrode current collector of the terminal power generation element is a conductive porous body such as an air electrode current collector (see FIG. 1 is preferably a conductive porous body 10). This is because by using the conductive porous body, a flow for efficiently discharging the unreacted portion of the oxygen-containing gas to the outside of the exterior body can be formed. Thus, when the negative electrode current collector has a porous structure, it is preferable to have an extended portion for the same reason as the air electrode current collector, and at least the surface of the extended portion is particularly coated with an insulating material. It is preferable. For the same reason as the air electrode current collector, the porous structure in the region in contact with the negative electrode layer is preferably closed.

  The manufacturing method of a negative electrode is not specifically limited. For example, there is a method in which a foil-like negative electrode active material and a negative electrode current collector are superposed and pressed. Another method includes preparing a negative electrode material mixture containing a negative electrode active material and a binder, and applying and drying the mixture on a substrate or a negative electrode current collector.

The power generation element is formed by laminating the air electrode, the electrolyte layer, and the negative electrode as described above, and is accommodated in the flexible exterior body.
Next, the flexible exterior body will be described.

[Flexible exterior body]
The flexible exterior body is formed of a flexible film, and can apply a pressure by an oxygen-containing gas from the outside of the exterior body to the power generation element accommodated in the exterior body. A flexible film will not be specifically limited if a pressure can be loaded as mentioned above, As a typical example, a laminate film is mentioned. The laminate film can be appropriately selected from those used as various battery exterior bodies. For example, one surface of the aluminum layer (external side of the exterior body) has impact resistance and A resin layer (for example, polyethylene terephthalate or nylon) for the purpose of material reinforcement is provided, and an adhesive layer (for example, made of polyolefin) for sealing the exterior body is provided on the other surface (inside the exterior body). Are provided.

  The flexible exterior body is provided with an oxygen intake hole that communicates with the air electrode current collector of the power generation element housed inside the flexible exterior body. The oxygen intake hole is particularly limited to the number, the cross-sectional shape, the arrangement position, the arrangement form, etc., as long as the oxygen-containing gas that restrains the power generation element from the outside of the flexible outer casing can reach the air current collector. There is no. For example, as shown in FIG. 1, the air electrode current collector 3 may be provided on a surface parallel to the surface direction, or the surface on which the positive electrode terminal 12 in FIG. 3 surface).

The oxygen-containing gas that restrains the power generation element and supplies oxygen from the outside of the flexible exterior body is an atmospheric pressure or higher, can constrain the power generation element in its stacking direction, and contains oxygen. Anything is acceptable.
The pressure applied to the power generation element by the oxygen-containing gas may be normal pressure (that is, atmospheric pressure) or higher, but is preferably about 0.1 MPa to 1 MPa. This is because even if the oxygen-containing gas is consumed by the discharge reaction, the pressurization can be continued at a certain pressure or higher.
As the oxygen-containing gas, air can be used in addition to pure oxygen gas, and the oxygen concentration is preferably 15 to 100% by volume, particularly pure oxygen gas (oxygen concentration 99.9% by volume). Is preferred. In addition, when moisture is contained in the oxygen-containing gas, there is a risk that corrosion of the metal constituting the power generation element or the like occurs. Therefore, the oxygen-containing gas is preferably a dry gas that does not contain moisture.

[Others]
An oxygen permeable film that selectively permeates oxygen may be disposed in the oxygen uptake hole of the flexible exterior body. This is to prevent intrusion of gas such as moisture and carbon dioxide from the outside of the flexible exterior body. From the same viewpoint, a water repellent film having water repellency may be disposed in the oxygen uptake hole.
As the oxygen permeable membrane, a general one (for example, polydimethylsiloxane) can be used, and the arrangement position may be inside or outside the flexible exterior body. Similarly, a general film (for example, polytetrafluoroethylene) can be used as the water-repellent film, and the arrangement position may be inside or outside the flexible exterior body.

Each of the air electrode and the negative electrode can be provided with a terminal serving as a connection portion with the outside.
The method for producing the metal-air battery of the present invention is not particularly limited, and a general method can be adopted.

[Example 1]
(Production of metal-air battery)
Carbon black (manufactured by Ketjen Black International Co., Ltd., ECP600JD) and polytetrafluoroethylene powder are mixed with an ethanol solvent so that the weight ratio is 90:10, and then roll-formed by a roll press to form an air electrode layer. Produced.
In addition, LiTFSA (manufactured by Kishida Chemical Co., Ltd.) was added to PP13TFSA (manufactured by Kanto Chemical Co., Ltd.) so as to have a concentration of 0.32 mol / kg, and stirred and dissolved overnight in an Ar atmosphere, and PVdF was weight ratio After mixing with an acetone solvent so that the ratio was 8: 2, the film was cast-coated on the substrate and dried to form a film. After peeling the substrate, the membrane was cut to obtain a gel electrolyte layer.
On the other hand, Ni foil (manufactured by Nilaco) was attached to metal Li (manufactured by Honjo Metal) (negative electrode layer).
Next, three Ni porous bodies (manufactured by Sumitomo Electric Industries) having different porosities were laminated so that the porosity increased in order, and press-molded to produce a conductive porous laminated body. The conductive porous laminate has a size and shape that is slightly larger than the outer peripheral edge of the air electrode layer, the electrolyte layer, and the metal Li-Ni foil laminate, and the air electrode layer and the electrolyte layer. And the surface of the extended part extended from the outer periphery of each layer when the laminated body and its center point were overlapped was subjected to polytetrafluoroethylene treatment.
The conductive porous laminate produced above, the air electrode layer, the electrolyte layer, and the negative electrode layer-Ni foil laminate were laminated in this order to produce a power generation element. The conductive porous laminate was laminated so that the layer with high porosity was on the air electrode layer side. The negative electrode layer-Ni foil laminate was laminated so that the negative electrode layer was on the electrolyte layer side.
Two power generation elements are prepared, the two power generation elements are overlapped so that the conductive porous laminate and the Ni foil are in contact with each other, and the conductive porous laminate is formed on the Ni foil located at the end. Were laminated. At this time, the conductive porous laminate laminated on the Ni foil was laminated so that the layer with low porosity was on the Ni foil side.
The obtained electrode laminate was accommodated in an exterior body made of an aluminum laminate film having oxygen uptake holes and sealed. A water repellent film made of tetrafluoroethylene was disposed in the oxygen uptake hole.

(Evaluation of metal-air battery)
The electrode laminate housed in the outer package was placed in a sealed container (1.1 atm = 0.11 MPa) filled with pure oxygen gas, and the sealed container was held at 60 ° C. while maintaining 0.1 mA / cm. ^The charge / discharge test was conducted under a constant current density of ² .
The open circuit voltage was 5.81 V, a discharge flat part at 2.6 V was observed, and continuous discharge for 112 hours was possible.

DESCRIPTION OF SYMBOLS 1 ... Air electrode 2 ... Air electrode layer 3 ... Air electrode collector 3A ... Extension part 4 ... Negative electrode (negative electrode layer)
5 ... Electrolyte layer 6 ... Power generation element (6A, 6B)
DESCRIPTION OF SYMBOLS 7 ... Flexible exterior body 8 ... Oxygen uptake hole 9 ... Gas flow path 10 ... Conductive porous body 11 ... Oxygen containing gas 12 ... Positive electrode terminal 13 ... Negative electrode terminal 100 ... Metal-air battery

Claims (5)

An air electrode having an air electrode layer containing oxygen as an active material, a negative electrode having a negative electrode layer containing a negative electrode active material, an electrolyte layer disposed between the air electrode layer and the negative electrode layer and conducting metal ions; Is a metal-air battery comprising a laminated power generation element, and a flexible exterior body formed of a flexible film that accommodates the power generation element,
The air electrode has a structure in which the air electrode layer and an air electrode current collector having a conductive and porous structure are sequentially stacked from the electrolyte layer side,
The flexible exterior body has an oxygen uptake hole communicating with the air electrode current collector,
Metallic air, wherein the power generation element is pressurized at a pressure equal to or higher than normal pressure in the stacking direction from the outside of the flexible exterior body by an oxygen-containing gas that supplies oxygen to the oxygen intake holes. battery.   The air electrode current collector has an outer peripheral edge of a surface orthogonal to the stacking direction of the power generation element extending from an outer peripheral edge of a surface orthogonal to the stacking direction of the air electrode layer, the electrolyte layer, and the negative electrode. The metal-air battery according to claim 1, wherein the metal-air battery has an existing part. The air electrode current collector has a size and shape in which the outer peripheral edge of the orthogonal surface is slightly larger than the outer peripheral edges of the air electrode layer, the electrolyte layer, and the negative electrode.
The air electrode current collector, the air electrode layer, the electrolyte layer, and the negative electrode are laminated with the center points of the orthogonal planes overlapped, and the extending part is the air electrode layer, the electrolyte layer, and the negative electrode. The metal-air battery according to claim 2, wherein the metal-air battery surrounds the outer peripheral edge of the battery.   The metal-air battery according to claim 2 or 3, wherein at least a surface of the extension part is covered with an insulating material. Two or more power generation elements are stacked and connected in series,
The metal-air battery according to any one of claims 1 to 4, wherein the porous structure is closed in a region where the air electrode current collector adjacent to the negative electrode layer is in contact with the negative electrode layer.

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