JP6206714B2 - Metal air battery - Google Patents

Description

  The present invention relates to an air battery that uses oxygen as a positive electrode active material, and in particular, it is not necessary to provide a water repellent film or air holes for taking in air on the positive electrode side, reducing costs by reducing the number of parts, mechanical strength The present invention relates to a metal-air battery capable of improving leakage resistance and reducing current collection loss during cell stacking.

A metal-air battery is a battery that uses oxygen in the air as a positive electrode active material and a metal such as aluminum (Al), iron (Fe), or zinc (Zn) as a negative electrode active material. Since it is not necessary to provide a substance, it has a high energy density and can be reduced in size and weight, and has attracted attention as an emergency power source or a driving power source for an electric vehicle or a ship.
As such a metal-air battery, for example, a battery having a structure described in Patent Document 1 is known.

JP 2006-19246 A

When such a metal-air battery is put into practical use, it is necessary to stack a large number of single cells in series so that an output voltage suitable for the purpose of use can be obtained.
At this time, ideally, it is desirable to stack the cells in series by directly contacting the positive electrode and the negative electrode.

In the metal-air battery as described above, the positive electrode (air electrode) has a water repellent film (liquid) made of polytetrafluoroethylene (PTFE) because of the necessity of taking in air from the outside and the necessity of preventing leakage of the electrolyte. It is covered with air diffusion paper in order to uniformly diffuse the air taken in from the air holes.
However, since these water repellent films and air diffusion paper are both made of an insulating material, they cannot directly conduct electricity.

  Therefore, the lead wires connected to the current collectors embedded in the positive electrode and the negative electrode, respectively, are pulled out in the lateral direction, and are connected in series by the positive electrode lead and the negative electrode lead. Then, there was a problem that current collection loss was very large.

  The present invention has been made to solve the above-described problems in conventional serial connection of metal-air batteries. The object of the present invention is to provide a water-repellent film made of an insulating material on the outer surface side of a positive electrode. It is an object of the present invention to provide a metal-air battery that can easily stack cells in series and reduce current collection loss.

  As a result of intensive studies aimed at achieving the above object, the present inventors have supplied oxygen from the inside of the battery, that is, to the electrolyte, instead of taking air into the positive electrode from the outside of the battery container. As a result, the inventors have found that the above object can be achieved, and have completed the present invention.

That is, the present invention is based on the above knowledge, and the metal-air battery of the present invention includes at least one set having a positive electrode and a negative electrode arranged opposite to each other in a battery container, and an electrolyte solution therebetween. The unit cell comprises a plurality of sets of unit cells connected in series, provided with oxygen supply means for supplying oxygen to the electrolyte solution, and a positive electrode catalyst layer constituting the positive electrode of the unit cell. Directly formed on the negative electrode metal plate of the adjacent unit cell, or on the current collector made of a metal plate provided with the negative electrode metal of the adjacent unit cell on the back side of the positive electrode catalyst layer constituting the positive electrode of the unit cell It is characterized by being formed directly .

  According to the present invention, since the oxygen supply to the positive electrode is made from the electrolyte solution side, it is not necessary to take in air from the outer surface side of the positive electrode, so a water repellent film or a diffusion paper made of an insulating material on the positive electrode side. It is not necessary to provide an air flow path, and series connection is possible by directly superposing the positive electrode and the negative electrode.

It is a section explanatory view showing the basic structure of the metal air battery by the present invention as a 1st embodiment. It is a schematic explanatory drawing which shows an example of the microbubble generator used as an oxygen supply means in this invention. (A) It is sectional explanatory drawing which shows the structural example of the assembled battery formed by connecting the metal-air battery in series as 2nd Embodiment of this invention. (B) It is an expanded sectional view explaining the electrode structure of the serial connection part in the metal air battery shown to Fig.3 (a). (C) It is sectional drawing explaining the other form of the electrode structure of the serial connection part in the metal air battery shown to Fig.3 (a). (D) It is sectional drawing explaining another form of the electrode structure of the serial connection part in the metal air battery shown to Fig.3 (a). It is a perspective view which shows the example of an electrode structure which fixed the circumference | surroundings of the electrical power collector provided with the positive electrode catalyst layer and the negative electrode metal on each surface as 3rd Embodiment of the metal air battery by this invention, respectively. It is a perspective view which shows the structural example which supplies oxygen-containing gas from the downward side of a battery container as 4th Embodiment of the metal air battery by this invention. It is a perspective view which shows the structural example which supplies oxygen-containing gas from the whole bottom face of a battery container as 5th Embodiment of the metal air battery by this invention. It is a perspective view which shows the structural example of the assembled battery made to circulate the electrolyte solution containing oxygen as 6th Embodiment of the metal air battery by this invention. It is a perspective view which shows the structural example of the assembled battery which consists of an injection type air battery which inject | pours the electrolyte solution containing oxygen as 7th Embodiment of the metal air battery by this invention. It is a perspective view which shows the decomposition | disassembly state of the battery structure of each example. 1 is a cross-sectional view showing a metal-air battery of Example 1. FIG. 6 is a perspective view showing a metal-air battery of Example 2. FIG.

  Hereinafter, various embodiments relating to the metal-air battery of the present invention will be specifically described.

  FIG. 1 is a cross-sectional view showing an example of the basic structure of the present invention as a first embodiment of the metal-air battery of the present invention. The metal-air battery 1 shown in the figure includes a positive electrode (air electrode) 2 and a negative electrode 3. And an electrolytic solution 4 is provided between the electrodes 2 and 3. Further, in the electrolyte solution 4, a nozzle 6 that is connected to an oxygen supply device (not shown) and forms a part of the oxygen supply means is disposed so as to open near the bottom of the battery container 5. In the embodiment, a gas G containing oxygen such as air is supplied from the nozzle 6 and bubbled into the electrolytic solution 4.

In the metal-air battery 1 having the above structure, oxygen is supplied to the positive electrode from the nozzle 6 connected to the oxygen supply device via the electrolytic solution 4, and as described above, from the outside of the positive electrode 2. Since it is not necessary to take in air, there is no need to dispose a water repellent film, diffusion paper, or air flow path on the positive electrode side. Therefore, the positive electrode current collector 2a and the negative electrode current collector 3a can be directly overlapped with each other, whereby series connection is simple and current collection loss can be reduced.
In addition, since there are no air holes or air flow paths for taking air into the battery container, it is possible to improve the container strength and leakage resistance, and to reduce costs by reducing the number of parts. can do.

The positive electrode 2 uses oxygen as a positive electrode active material, and includes a positive electrode current collector 2a made of stainless steel and the like, and a positive electrode catalyst layer 2b formed on the positive electrode current collector 2a. A redox catalyst and a conductive catalyst carrier supporting the redox catalyst.
Examples of the catalyst component include metal oxides such as manganese dioxide and tricobalt tetroxide, platinum (Pt), ruthenium (Ru), iridium (Ir), rhodium (Rh), palladium (Pd), and osmium (Os). ), Tungsten (W), lead (Pb), iron (Fe), chromium (Cr), cobalt (Co), nickel (Ni), manganese (Mn), vanadium (V), molybdenum (Mo), gallium (Ga) ), Metals such as aluminum (Al), and alloys thereof.

The shape and size of the catalyst component are not particularly limited, and the same shape and size as those of conventionally known catalyst components can be employed. However, the shape of the catalyst component is preferably granular, and the average particle diameter of the catalyst particles is preferably 1 to 30 nm.
When the average particle diameter of the catalyst particles is within such a range, it is possible to appropriately control the balance between the catalyst utilization rate related to the effective electrode area where the electrochemical reaction proceeds and the ease of loading.

The catalyst carrier functions as a carrier for supporting the catalyst component, and also as an electron conduction path involved in the transfer of electrons between the catalyst component and another member. Any catalyst carrier may be used as long as it has a specific surface area for supporting the catalyst component in a desired dispersion state and sufficient electron conductivity, and the main component is preferably carbon. Specific examples of the catalyst carrier include carbon particles made of carbon black, activated carbon, coke, natural graphite, artificial graphite, and the like.
The size of the catalyst carrier is not particularly limited, and the average particle diameter is preferably about 5 to 200 nm, preferably from the viewpoint of easy loading, catalyst utilization, and control of the catalyst layer thickness within an appropriate range. Is preferably about 10 to 100 nm.

The amount of the catalyst component supported on the catalyst carrier is preferably 1 to 80% by mass, more preferably 3 to 40% by mass, based on the total amount of the catalyst and the carrier on which the catalyst is supported. When the supported amount of the catalyst component is within such a range, the balance between the degree of dispersion of the catalyst component on the catalyst carrier and the catalyst performance becomes appropriate.
It should be noted that the above-described catalyst component and the type of the carrier supporting the catalyst component are not limited to those described above, and it goes without saying that conventionally known materials applicable to air batteries can be used as appropriate. .

Furthermore, in the metal-air battery of the present invention, the positive electrode catalyst layer 2b desirably has an oxygen adsorption function or an oxygen-containing gas trap function, thereby increasing the amount of oxygen involved in the discharge. The capacity can be increased.
For example, a gas trap function can be imparted to the positive electrode catalyst layer 2b by adding a water-repellent resin such as a fluorine-based resin or a porous material whose surface is processed such as rubber or resin. Further, by adding activated carbon, mesoporous silica, silica gel or the like, an oxygen adsorption function can be exhibited.

The negative electrode 3 includes a negative electrode current collector 3a made of copper or the like and a negative electrode metal 3b formed thereon. In addition, when using a metal board | plate material as the negative electrode metal 3b, this can also be utilized as a collector.
As the negative electrode metal 3b, a single metal whose standard electrode potential is lower than hydrogen or an alloy containing these metals is used. Examples of such a simple metal include zinc (Zn), iron (Fe), aluminum (Al), and magnesium (Mg). Examples of the alloy include those obtained by adding one or more metal elements or non-metal elements to these metal elements. However, the material is not limited to these, and a conventionally known material applied to the air battery can be applied.

  As the electrolytic solution 4, for example, an aqueous solution of potassium chloride (KCl), sodium chloride (NaCl), potassium hydroxide (KOH), sodium hydroxide (NaOH), or the like is used, but is not limited thereto. A conventionally well-known electrolytic solution applied to an air battery can be applied. Also, by using alcohols such as pentanol and propanol, nonionic surfactants, amphoteric surfactants, cationic surfactants, anionic surfactants, etc. as additives, It is possible to reduce the speed of ascent.

  As the oxygen supply means, for example, an air pump is used as an oxygen supply device, and a gas G containing oxygen such as air is blown out and bubbled through the nozzle 6 through the nozzle 6. Note that air is generally used as the gas G containing oxygen, but it is also desirable to use pure oxygen, ozone, or the like as necessary in order to increase the utilization rate of oxygen.

In bubbling such a gas G, it is particularly preferable to perform bubbling with microbubbles, that is, microbubbles or nanobubbles.
In other words, by supplying the oxygen-containing gas in the form of such a microbubble, the residence time of the gas in the electrolytic solution becomes long, and the dissolved oxygen concentration in the electrolytic solution can be kept high even with a small supply amount. In addition, the oxygen utilization rate can be improved and the discharge voltage can be stabilized.

Here, microbubbles are defined as “bubbles having a diameter of 10 to several tens of μm at the time of their occurrence”, and most microbubbles shrink in the liquid, and micronanobubbles (diameters of about 1 μm to several μm). It changes into a bubble of 100 nm, becomes a micro-nano bulb, and further rapid contraction occurs, and the bubble disappears by dissolving in the liquid.
Ordinary bubbles (millibubbles or more) rise rapidly in the electrolyte and burst at the liquid level, and oxygen in the bubbles is unnecessarily released into the atmosphere. On the other hand, microbubbles have a small bubble volume, so the rising speed is slow and they stay in the liquid for a long time. Note that the rising speed of the microbubbles is expressed by the Stokes equation. For example, the rising speed of the bubbles having a diameter of 10 μm is only about 3 mm per minute.

Such an interface is formed between two phases of a gas phase and a liquid phase, a liquid phase and a liquid phase, a liquid phase and a solid phase, and a solid phase and a solid phase, and pressurization occurs between the interfaces due to an interfacial tension. This interfacial tension is derived from the Young Laplace equation, and the pressure applied to the bubbles increases in inverse proportion to the size of the bubbles. For this reason, the fine bubbles are further reduced by the pressure, the pressure is further increased, and theoretically infinite pressure is generated, so that the gas is effectively dissolved in the liquid.
Furthermore, since the microbubble has a side surface as a colloid and is negatively charged, the microbubbles repel each other, so the microbubbles are not bonded to each other, and the bubble concentration is not reduced.

Such microbubbles and nanobubbles can be generated by various known methods.
For example, if a sufficient amount of gas is dissolved in the liquid under a certain level of pressure and then the pressure is released, the gas is supersaturated in the liquid, so the supersaturated gas molecules are vaporized in the liquid. As a result, a large amount of microbubbles can be generated (pressure reduction method).

Moreover, in order to generate | occur | produce microbubble continuously, as shown in FIG. 2, the generator to which the pump is applied can be used. The pump takes in water (electrolytic solution in the present invention) from the suction side and discharges it from the extrusion side. At this time, the pressure on the suction side is lower than the environmental pressure and the extrusion side is higher than the environmental pressure. By providing a nozzle at the end on the extrusion side, the pressure difference can be further increased.
If a gas dissolution tank is placed in the path on the extrusion side, the gas (oxygen-containing gas) taken in at a high pressure can be dissolved in the electrolyte, and the pressure is released when the electrolyte is discharged from the nozzle. In addition, since the dissolved gas becomes supersaturated, a large amount of microbubbles can be generated.

Furthermore, it is also possible to apply a method (gas-liquid two-phase flow swirl method: gas-liquid shear method) in which a vortex is created, gas is entrained, and bubbles are further cut and pulverized with a fan or the like.
That is, a liquid flow is generated in a cylindrical container using a pump, a vortex is generated by a circular inclined plate or a bell-shaped rotary drive unit, and gas is entrained therein. A cylindrical container has a shaft, and microbubbles can be generated by stirring the liquid and gas so as to shear with a propeller attached to the shaft. Although this method is not suitable for the generation of high-concentration bubbles, the gas and liquid are mixed directly, and the liquid flow is large and microbubbles can be generated efficiently.

  As described above, bubbling of oxygen-containing gas, particularly bubbling of microbubbles and nanobubbles, has been described, but the oxygen supply method by the oxygen supply means in the present invention is not limited to only gas bubbling as described above, For example, an oxidizing agent such as hydrogen peroxide may be mixed in the electrolytic solution 4.

Fig.3 (a) is sectional drawing which shows the state by which the said metal air battery 1 was connected in series as 2nd Embodiment of the metal air battery of this invention.
Although this figure shows a state in which two unit cells are connected, it goes without saying that the same is basically true even when three or more cells are connected in series.

The connection structure shown in FIG. 3 (a) is basically a structure in which two air cells 1 shown in FIG. 1 are arranged side by side and connected in series, but the positive electrode located between adjacent unit cells. And the structure of the negative electrode is simplified.
That is, when the air batteries 1 shown in FIG. 1 are connected in series as they are, the positive electrode current collector 2a having the positive electrode catalyst layer 2b on the back side and the negative electrode current collector 3a having the negative electrode metal 3b are connected. Thus, the positive electrode current collector 2a and the negative electrode current collector 3a are connected to each other to form a current collector made of two stacked metal plates. In the present invention, even such an assembled battery has no problem in practical use, but is wasted in terms of materials and processes.

Therefore, in the assembled battery shown in FIG. 3 (a), as shown in an enlarged view in FIG. 3 (b), the positive electrode current collector 2a and the negative electrode current collector 3a in the central portion, that is, the electrode at the connection portion, The positive electrode catalyst layer 2b is formed on one surface of the current collector 7 made of a single metal plate, and the negative electrode metal 3b is provided on the other surface.
Thereby, the contact resistance between the positive electrode current collector 2a and the negative electrode current collector 3a is eliminated, and the current collection loss can be further reduced.

  Further, as shown in FIG. 3C, the current collector 7 is omitted, and the positive electrode catalyst layer 2b is formed on the negative electrode metal 3b, whereby the negative electrode metal 3b is also used as a current collector. As a result, the current collector 7 becomes unnecessary, and the cost can be reduced.

  Further, as shown in FIG. 3 (d), an oxygen-containing gas is supplied to the electrolytic solution by using a porous metal plate having air permeability as the current collector 7, while the porous current collector is provided. It is also desirable to supply oxygen-containing gas from the body 7 'as necessary.

  The assembled battery comprising the metal-air battery of the present invention comprises a current collector 7 (or 7 ′), a positive electrode catalyst layer 2b, and a negative electrode as shown in FIGS. A plurality of positive electrode-negative electrode assemblies made of the metal 3b or the positive electrode active material layer 2b and the negative electrode metal 3b are arranged in parallel.

At this time, as shown in FIG. 4, a positive electrode-negative electrode assembly having a positive electrode catalyst layer 2b on one surface of the current collector 7 and a negative electrode metal 3b on the other surface (the side not visible in the figure), or a negative electrode It is preferable to use what fixed the metal part around the positive electrode-negative electrode assembly formed by forming the positive electrode catalyst layer 2b on the metal 3b to the frame member 9.
By stacking a large number of such frame bodies 9 integrated with the positive electrode and the negative electrode and joining them at the frame portion, a strong assembled battery having a desired output and excellent in leakage resistance can be obtained. It is not necessary to arrange the positive electrode active material layer 2b or the negative electrode metal 3b on the outer side for the electrodes arranged at both ends, but it is easy to manage and assemble by unifying the parts to reduce the number of parts. From the point of view, the same frame body 9 may be disposed at both ends.

  When supplying oxygen to the electrolytic solution, especially when the means is bubbling of an oxygen-containing gas, supplying the oxygen-containing gas from the lower side of the battery container may increase the dissolved oxygen in the electrolytic solution. This is desirable because it improves the oxygen utilization rate.

For example, FIG. 5 shows an assembled battery composed of six single cells. As shown in the figure, an oxygen-containing gas G (for example, air) is supplied from a pump 10 which is an oxygen supply device to the bottom between the electrodes. By supplying from the six nozzles 6 arranged, the floating path of the gas G becomes longer, and the residence time in the electrolyte can be increased.
At this time, it is desirable from the viewpoint of improving the utilization rate of oxygen to supply the oxygen-containing gas G toward the positive electrode 2 by directing the gas ejection direction of the nozzle 6 toward the positive electrode catalyst layer 2b.

  In addition, as shown in FIG. 6, it is also desirable to supply the oxygen-containing gas G through the porous body 11 made of resin or ceramics disposed on the bottom surface of the battery container, thereby bubbling the gas G from the entire bottom surface. It is possible to increase the contact area between the electrolyte and the bubbles.

FIG. 7 shows an example of the structure of an electrolyte circulation type assembled battery as another embodiment of the metal-air battery of the present invention. The assembled battery shown in FIG. And an electrolytic solution tank 12 containing the electrolytic solution 4 and a circulating means 13 for circulating the electrolytic solution in the tank 12 between the electrodes.
In the assembled battery according to this embodiment, a nozzle 6 connected to an oxygen supply device 10 such as a pump is provided in the electrolyte tank 12 as an oxygen supply means, and the oxygen-containing gas G causes the nozzle 6 to be connected. And bubbling into the electrolyte solution 4 in the electrolyte solution tank 12.

Therefore, the electrolytic solution in which oxygen is dissolved in the electrolytic solution tank 12 is circulated between the electrolytic solution tank 12 and the electrodes in the battery container by the circulation means 13 by bubbling of the gas G.
In this figure, the example in which the electrolytic solution is circulated by supplying from the upper side of the electrode and discharged from the lower side of the battery container is shown, but it is supplied from the lower side of the electrode and recovered from the upper side. It is also possible to do. Further, it is also desirable to use a microbubble generator as shown in FIG. 2 as the oxygen supply means. By using this, the amount of dissolved oxygen in the electrolyte can be increased.

FIG. 8 shows an example of the structure of an injection type assembled battery as still another embodiment of the metal-air battery of the present invention. The assembled battery shown in FIG. Further, similarly to the circulation type air battery shown in FIG. 7, an electrolyte tank 12 including an oxygen-containing gas G bubbling device (oxygen supply means) is further provided.
In such an injection type assembled battery, oxygen is sufficiently dissolved in the electrolytic solution by bubbling the oxygen-containing gas G from the nozzle 6 connected to the oxygen supply device 10 such as a pump, and then illustrated. By opening the valve that does not, the electrolyte containing oxygen flows into the battery container, thereby starting the battery reaction and starting the discharge. Until then, there is no consumption or alteration of the active material, so that semi-permanent storage is possible.

  Hereinafter, the power generation performance of the metal-air battery of the present invention will be specifically described based on examples, but the present invention is not limited to these examples.

[Battery structure]
(1) Positive electrode As a commercially available water-repellent layer, W.W. L. Gore & Associates, Inc. A Teflon sheet having a thickness of 100 μm and a 200 mesh stainless mesh made by Taiyo Wire Mesh Co., Ltd. were used as a current collector. Moreover, what mixed the catalyst layer by the following ratio by solid content ratio was used.
Commercially available manganese oxide powder (High Purity Chemical Laboratory Co., Ltd.) 30% by mass
Commercially available carbon (Ketjen Black) powder (Lion Corporation) 40% by mass
30% by mass of commercially available PTFE dispersion (Asahi Glass Co., Ltd.)
About the comparative example, what mixed manganese oxide powder, Ketjen black, and PTFE dispersion liquid was dried, and roll-formed so that a catalyst layer might be 0.5 mm thick with a metal mesh and a water repellent layer.
In Examples, a mixture of manganese oxide powder, ketjen black, and PTFE dispersion was dried and roll-formed with a 0.1 mm thick SUS316 (stainless steel) plate so that the catalyst layer had a thickness of 0.5 mm.
(2) Negative electrode A Zn plate (0.5 mm thick) was joined to a Cu foil (0.1 mm thick) by spot welding.
(3) Electrolytic solution 8N-KOH was used as the electrolytic solution.
(4) Oxygen supply means Example 1: A chemical-resistant tube was placed in a cell, and dry air at a flow rate shown in Table 1 was supplied by bubbling (see FIG. 10).
Example 2: A chemical-resistant tube was placed in the cell, and the electrolytic solution was circulated with a pump at a rate of 50 cc / min. The circulation tube was connected to an electrolytic solution container filled with 1 L of electrolytic solution, and the described amount of dry air was supplied to the electrolytic solution by a microbubble generator (see FIG. 11).
In the comparative examples, 100 cc / min, 50 cc / min, and 0 (no forced supply when open to the atmosphere) were supplied from the outside of the cell.
(5) Battery structure The positive electrode and the negative electrode were cut out so that the electrode size was 10 cm × 10 cm. A 1 mm thick polypropylene (PP) plate is cut out to a width of 11 mm, joined to the end of each electrode so that it becomes 10 cm × 10 cm, the upper part is opened, and an epoxy-based adhesive that covers the three sides (Cemedine) was attached to the positive and negative electrodes (see FIG. 9).

[Performance evaluation method]
The current value was measured when the cell voltage was controlled to 1 V using a potentiostat. The obtained results are shown in Table 1.

  From the above results, it was confirmed that continuous discharge was possible by supplying gas directly to the electrolyte without using a water repellent layer.

DESCRIPTION OF SYMBOLS 1 Metal-air battery 2 Positive electrode 2a Positive electrode collector 2b Positive electrode catalyst layer 3 Negative electrode 3a Negative electrode collector 3b Negative electrode metal 4 Electrolyte 5 Battery container 6 Nozzle (oxygen supply means)
9 Frame material 10 Oxygen supply device (oxygen supply means)
12 Electrolyte tank 13 Circulation means G Oxygen-containing gas

Claims (9)

Metal air formed by housing a plurality of sets of unit cells connected in series at least one set of unit cells having a positive electrode and a negative electrode disposed in opposition to each other and an electrolyte therebetween. In batteries,
Providing an oxygen supply means for supplying oxygen to the electrolyte ;
The positive electrode catalyst layer constituting the positive electrode of the single cell is directly formed on the negative electrode metal plate of the adjacent single cell, or the negative electrode metal of the single cell adjacent to the positive electrode catalyst layer constituting the positive electrode of the single cell is backside A metal-air battery, wherein the metal-air battery is directly formed on a current collector made of a metal plate provided on the side . The metal-air battery according to claim 1 , wherein a frame member is fixed around the negative electrode metal or the current collector. The metal-air battery according to claim 1 or 2 , wherein the positive electrode catalyst layer constituting the positive electrode has an oxygen adsorption function or a gas trap function. The metal-air battery according to any one of claims 1 to 3, wherein the oxygen supply means supplies oxygen from a lower side of the battery container. The metal-air battery according to any one of claims 1 to 4, wherein the oxygen supply means supplies oxygen toward the positive electrode. An electrolyte tank, equipped with a circulating means for circulating the electrolyte between the tank and the battery case, either of the preceding claims in which the oxygen supply means and supplying oxygen to the electrolyte solution in the tank The metal-air battery according to any one item . The metal air battery according to any one of claims 1 to 5, wherein the air battery is a liquid injection type, and the oxygen supply means supplies oxygen to the electrolyte before the liquid injection. The metal-air battery according to any one of claims 1 to 7, wherein the oxygen supply means supplies oxygen into the electrolytic solution by bubbling a gas containing oxygen. The metal-air battery according to claim 1, wherein the current collector is a current collector excluding a porous current collector.

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