JP7465340B2 - Metal-air battery device - Google Patents

Description

The present invention relates to a metal-air battery device. This disclosure claims priority to Japanese Patent Application No. 2020-069047, filed on April 7, 2020, the contents of which are incorporated herein by reference.

For example, Patent Document 1 describes an example of a metal-air battery device that houses multiple metal-air batteries. The metal-air battery described in Patent Document 1 has a positive electrode, a negative electrode, a separator disposed between the positive and negative electrodes, an electrolyte, and an exterior body that houses the positive electrode, the negative electrode, the separator, and the electrolyte. An opening is formed on the surface of the exterior body on the positive electrode side, and a water-repellent film is disposed between the exterior body and the positive electrode.

JP 2019-67616 A

In the metal-air battery device described in Patent Document 1, for example, each metal-air battery provided in the metal-air battery device expands upon discharging, which may cause a concern of a deterioration in battery characteristics, such as a decrease in discharge capacity and rate characteristics.
A main object of the present disclosure is to provide a metal-air battery device in which deterioration of battery characteristics is suppressed.

A metal-air battery device according to one embodiment of the present invention comprises at least one metal-air battery having a positive electrode, a negative electrode arranged opposite the positive electrode, and an exterior body that houses the positive electrode and the negative electrode, and a restricting member that contacts the at least one metal-air battery from the outside and partially restricts the at least one metal-air battery to a thickness equal to or less than a predetermined thickness.

FIG. 1 is a plan view illustrating an example of a metal-air battery according to a first embodiment. 2 is a cross-sectional view taken along line AA in FIG. 1. FIG. 1 is a diagram showing another example of a metal-air battery. FIG. 1 is a schematic cross-sectional view showing an example of a metal-air battery device according to a first embodiment. FIG. 5 is a plan view illustrating an example of a restricting member in FIG. 4 . FIG. 2 is a front view showing an example of a state in which a restricting member is provided in a metal-air battery. FIG. 11 is a front view showing a state in which another example of a restricting member is provided in the metal-air battery. FIG. 13 is a front view showing a state in which still another example of a restricting member is provided in the metal-air battery.

Hereinafter, an example of a preferred embodiment of the present invention will be described. However, the following embodiment is merely an example. The present invention is not limited to the following embodiment.

<Embodiment 1>
An example of a metal-air battery 10 provided in a metal-air battery device 1 according to the present embodiment will be described with reference to Figures 1 and 2. Figure 1 is a front view of the metal-air battery 10. Figure 2 is a cross-sectional view taken along the line AA in Figure 1.

As shown in FIG. 1, the metal-air battery 10 includes an exterior body formed by bonding a first resin film 11 and a second resin film 12 together. The metal-air battery 10 further includes an air electrode (positive electrode) 13, a metal negative electrode (negative electrode) 14, a separator 25, and a water-repellent film 16 housed inside the exterior body. The interior of the exterior body is filled with an electrolyte (not shown), such as an alkaline aqueous solution (e.g., a KOH aqueous solution). The electrolyte is interposed between the air electrode 13 and the metal negative electrode 14 and includes an electrolyte that transfers electric charge between the air electrode 13 and the metal negative electrode 14.

The first resin film 11 has an air intake port 111 as an opening for taking in air into the first storage section S11 described later. The first resin film 11 can be a resin film used in known metal-air batteries. More specifically, the first resin film 11 can be welded to the second resin film 12 and is preferably formed from a thermoplastic resin having excellent alkali resistance, for example, a polyolefin resin film such as polypropylene or polyethylene. For reinforcement, a resin film layer such as nylon (registered trademark) or polyethylene terephthalate or a metal film layer such as aluminum foil or stainless steel foil may be laminated on the outside air side of the first resin film 11 and the second resin film 12. The thickness of the first resin film 11 is not particularly limited, but is preferably 0.02 mm to 0.25 mm. If the thickness of the first resin film 11 is less than 0.02 mm, the film may not be sufficiently fused when welded, resulting in insufficient bonding strength, whereas if the thickness of the first resin film 11 exceeds 0.25 mm, the film may be difficult to stretch, causing stress to concentrate at the welded portion when the battery expands, resulting in the welded portion peeling off. In addition, the opening ratio of the air intake 111 to the first resin film 11 is preferably 10% to 70%.

The second resin film 12 is disposed opposite the first resin film 11. The second resin film 12 can be appropriately selected from the resin films used for the first resin film 11. For the same reasons as for the first resin film 11, the thickness of the second resin film 12 is preferably 0.02 mm to 0.25 mm.

The separator 15 is disposed opposite the first resin film 11 and the second resin film 12. That is, the separator 15 is provided between the first resin film 11 and the second resin film 12. The peripheral portion of the separator 15 is welded to the peripheral portion of the first resin film 11. The peripheral portion of the separator 15 may be welded to the peripheral portion of the second resin film 12, or may be welded to both the peripheral portion of the first resin film 11 and the peripheral portion of the second resin film. The separator 15 may be made of a separator material commonly used in the field of metal-air batteries, as long as it is a material that can be welded to the first resin film 11 or the second resin film 12. The thickness of the separator 15 is not particularly limited, but is preferably 0.05 mm to 0.4 mm. If the thickness of separator 15 is less than 0.05 mm, there is a risk that separator 15 will break due to the volume expansion of the negative electrode active material during discharge. On the other hand, if the thickness of separator 15 exceeds 0.4 mm, there is a risk that the battery output will decrease as a result of an increase in internal resistance.

The first storage section S11 is between the first resin film 11 and the separator 15. The first storage section S11 contains the air electrode 13 and the water-repellent film 16. More specifically, the water-repellent film 16 is slightly larger than the air intake 111 and is welded to the first resin film 11 so as to cover the air intake 111 from the inside. The air electrode 13 is disposed between the water-repellent film 16 and the separator 15.

The water-repellent film 16 is provided to take in air from the air inlet 111 to the air electrode 13 and to prevent leakage of the electrolyte from the air inlet 111, and has air permeability and gas-liquid separation function. The water-repellent film 16 is fixed to the first resin film 11 by welding or the like so as to cover the air inlet 111 from the inside. The material of the water-repellent film 16 is not particularly limited as long as it is a material that is commonly used in the field of metal-air batteries and can be fixed to the first resin film 11. The thickness of the water-repellent film 16 is preferably 0.05 mm to 0.5 mm. In this embodiment, the water-repellent film 16 is exposed to the outside of the metal-air battery 10 and can be said to be part of the exterior body.

The air electrode 13 is composed of, for example, a catalyst layer 132 and a positive electrode collector 131 disposed inside the catalyst layer 132. A part of the positive electrode collector 131 extends outside the exterior body and serves as a lead portion 133 of the metal-air battery 10. The positive electrode collector 131 is not particularly limited as long as it is made of a conductive material such as a metal that is commonly used in the field of metal-air batteries. The thickness of the positive electrode collector 131 is not particularly limited, but is preferably 0.05 mm to 0.5 mm.

The catalyst layer 132 includes at least an air electrode catalyst. The air electrode catalyst is a catalyst having at least an oxidation-reduction ability. Examples of the air electrode catalyst include conductive carbon such as ketjen black, acetylene black, denka black, carbon nanotubes, and fullerene, metals such as platinum, metal oxides such as manganese oxide, metal hydroxides, and metal sulfides, and one or more of these can be used. This makes it possible to form a three-phase interface in which oxygen gas, water, and electrons coexist on the air electrode catalyst, and allows the discharge reaction to proceed. When the metal-air battery 10 is a primary battery as in this embodiment, the catalyst layer 132 can include a catalyst such as manganese dioxide. In addition, the metal-air battery 10 may be a secondary battery, and in this case, the catalyst layer 132 may include not only an air electrode catalyst having oxygen reduction ability, but also a catalyst having oxygen generation ability, or may include a bi-functional catalyst having both oxygen generation ability and oxygen reduction ability.

The mass ratio of the air electrode catalyst contained in the catalyst layer 132 is preferably 5 mass% or more of the catalyst layer 132. The air electrode catalyst layer may contain a binder in addition to the air electrode catalyst. In addition, a binder such as polytetrafluoroethylene can be used for the catalyst layer 132. The thickness of the catalyst layer 132 is preferably 0.1 mm or more and 1.0 mm or less.

The second storage section S12 is between the second resin film 12 and the separator 15. The metal negative electrode 14 is stored in the second storage section S12. In the second storage section S12, the peripheral portion of the separator 15 may be welded to the peripheral portion of the second resin film 12. However, even when the separator 15 and the second resin film 12 are welded, it is the welded portion between the first resin film 11 and the second resin film 12 that forms the outer periphery of the second storage section S12.

The metal negative electrode 14 is, for example, disposed opposite the air electrode 13 and includes a negative electrode collector 141 and a negative electrode active material layer 142. The negative electrode active material layer 142 includes at least a negative electrode active material. More specifically, the metal negative electrode 14 is formed by separately putting the negative electrode collector 141 and a particulate negative electrode active material (e.g., zinc or zinc oxide) into the second storage section S12. A part of the negative electrode collector 141 extends to the outside of the exterior body and becomes the lead part 143 of the metal-air battery 10. The thickness of the negative electrode collector 141 is not particularly limited, but is preferably 0.05 mm to 0.50 mm. In addition, a resin additive for improving the binding property and rheological properties of the negative electrode active material may be appropriately included.

The negative electrode active material is appropriately selected from materials commonly used in the field of metal-air batteries. For example, metal species such as cadmium, lithium, sodium, magnesium, lead, zinc, tin, aluminum, and iron can be used as the negative electrode active material. For example, when the metal-air battery 10 is a secondary battery, the negative electrode active material may be in the form of a metal oxide since it is reduced when charged.

The negative electrode active material preferably has an average particle diameter of 1 nm to 500 μm. More preferably, it is 5 nm to 300 μm, even more preferably, it is 100 nm to 250 μm, and particularly preferably, it is 200 nm to 200 μm. The above average particle diameter can be measured using a particle size distribution measuring device.

The second storage section S12 also contains an electrolyte (not shown) that is appropriately selected depending on the type of metal used in the negative electrode active material. The metal negative electrode 14 may be in the form of a slurry in which the negative electrode active material is dispersed in the electrolyte (in other words, a slurry-like negative electrode active material layer 142). In this case, the ratio of the weight of the electrolyte to the weight of the negative electrode active material is preferably 0.3 to 2.0. In this case, the particle size of the negative electrode active material is preferably 10 μm to 800 μm, and more preferably 75 μm to 425 μm.

In the metal-air battery 10 of this embodiment, the first resin film 11, the second resin film 12, the air electrode 13, the metal negative electrode 14, the separator 15, the water-repellent film 16 and the electrolyte can all be those conventionally used in the field of metal-air batteries.

Next, an example of a manufacturing method for the metal-air battery 10 will be described.

First, an air intake port 111 is formed in the first resin film 11 (a first resin film 11 having an air intake port 111 formed therein is prepared).

Then, the water-repellent film 16 is adhered to the first resin film 11 so as to cover the air intake 111. At this time, the water-repellent film 16 is slightly larger than the air intake 111, and the water-repellent film 16 is laminated and heat-welded to the edge portion (adhesive area) of the air intake 111.

Next, a catalyst layer 132 is laminated on the surface of the water-repellent film 16 opposite the air intake port 111.

Furthermore, the positive electrode collector 131 is laminated on the catalyst layer 132 so that one side extends beyond the adhesive region, and these are pressed together. The positive electrode collector 131 may further include a lead portion 133 electrically connected to the extension portion of the positive electrode collector 131, and a tab film may be attached to both sides of the lead portion 133.

Next, the separator 15 is laminated on the positive electrode current collector 131, and the separator 15 is heat-welded to the first resin film 11. At this time, the separator 15 is slightly larger than the water-repellent film 16, and is welded to the first resin film 11 where it overlaps. If a tab film is used for the lead portion, the separator 15 is heat-welded to the tab film where it overlaps.

Next, the negative electrode current collector 141 is laminated on the separator 15. A lead portion 143 electrically connected to the negative electrode current collector 141 may be further provided, and a tab film may be attached to both sides of the lead portion 143.

Furthermore, the second resin film 12 is laminated on the negative electrode current collector 141, and each of the three sides except for the bottom side (the side where the lead portions 133 and 143 do not extend outside the exterior body, for example, the side opposite the side where the lead portions 133 and 143 extend outside the exterior body) is heat welded. At this time, at least the overlapping portions of the first resin film 11 and the second resin film 12 are heat welded on the two side sides. At least the overlapping portions of the first resin film 11 and the second resin film 12 are heat welded on the top side.

Finally, an electrolyte consisting of, for example, zinc powder as the negative electrode active material and a 7M KOH aqueous solution is poured into the opening on the one side (bottom side) that is not welded, and then that side is glued. At this point, the separator 15 is already welded to the first resin film 11. On the bottom side, the overlapping portion of the resin films (first resin film 11 and second resin film 12) is heat welded so that the weld width is, for example, 4 mm.

Note that the metal-air battery 10 in this embodiment is not limited to the above configuration, and may have a structure having a second air electrode in which a separator 15, a positive electrode current collector 131, a catalyst layer 132, a water-repellent film 16, and a first resin film 11 are laminated on top of a negative electrode sandwiched between the second resin film in the above configuration as shown in FIG. 3. In addition, instead of the second air electrode, a charging positive electrode having oxygen generation catalytic ability may be used. The charging positive electrode is, for example, an electrode containing Ni having oxygen generation catalytic ability.

Next, an example of a metal-air battery device 1 according to this embodiment will be described with reference to Figures 4, 5, and 6. Figure 4 is a schematic side view of the metal-air battery device 1. Figure 5 is a plan view showing an example of a restricting member 21. Figure 6 is a front view of a metal-air battery with the restricting member 21 attached.

As shown in Fig. 4, the metal-air battery device 1 according to this embodiment includes at least one metal-air battery 10 arranged in a direction in which an air electrode 13 and a metal negative electrode 14 are stacked within a housing 20. Fig. 4 illustrates an example in which three metal-air batteries 10 are arranged within the housing 20, but the number of metal-air batteries 10 is not particularly limited and may be more than one.

5, the restricting member 21 includes, for example, linear rod-shaped portions 21a, 21b, 21c, and 21d, and connecting portions 21e and 21f. The restricting member 21 has a structure in which the rod-shaped portions 21a, 21b, 21c, and 21d are connected by connecting portions 21e and 21f. The restricting member 21 also has a ring-shaped portion 21g surrounded by adjacent rod-shaped portions 21a and 21b and connecting portions 21e and 21f. Similarly, the portion surrounded by adjacent rod-shaped portions 21b and 21c and connecting portions 21e and 21f, and the portion surrounded by adjacent rod-shaped portions 21c and 21d and connecting portions 21e and 21f are also ring-shaped portions. Each ring-shaped portion is the same as the ring-shaped portion 21g. Each metal-air battery 10 is inserted through the ring-shaped portion 21g and each ring-shaped portion. The material of the restricting member 21 is not particularly limited, and may have flexibility in accordance with the expansion of the metal-air battery 10. The thickness of the restricting member 21 is not particularly limited, and if the restricting member 21 is too thin, it is easily damaged, and if it is too thick, it will block the air intake port 111 of the metal-air battery 10, leading to a decrease in battery performance. The thickness of the restricting member 21 is, for example, 0.5 mm or more and 5 mm or less. In this embodiment, the restricting member 21 has a structure in which three ring-shaped portions are connected together, but is not limited thereto, and may have a structure in which a single ring-shaped portion is connected together or a plurality of ring-shaped portions are connected together.

More specifically, the metal-air battery 10 (exterior body) in the metal-air battery device 1 is sandwiched from the outside by the rod-shaped portion 21a and the rod-shaped portion 21b in the stacking direction in which the air electrode 13 and the metal negative electrode 14 are stacked. The distance between the rod-shaped portion 21a and the rod-shaped portion 21b at this time is L1. In other words, the metal-air battery 10 is restricted to a thickness equivalent to the distance L1 between the rod-shaped portion 21a and the rod-shaped portion 21b. The metal-air battery 10 is formed with a curved portion 10a that is curved by the rod-shaped portions 21a and 21b, and is divided into a first portion 10b and a second portion 10c at the contact portion with the rod-shaped portions 21a and 21b. In other words, the rod-shaped portions 21a and 21b curve the metal-air battery 10, that is, the exterior body. With the above configuration, the thickness of the curved portion 10a of the metal-air battery 10, in other words the above-mentioned specified thickness, is thinner than the thickness of the metal-air battery 10 when it is not restricted by the rod-shaped portions 21a and 21b.

The width of the rod-shaped parts 21a and 21b in the stacking direction is not particularly limited, but it is preferable that the width is as small as possible so that the water-repellent films 16 of adjacent metal-air batteries 10 do not come into contact with each other and block the air intake port 111 when the metal-air battery 10 expands. By reducing the width of the rod-shaped parts 21a and 21b, the metal-air battery device 1 can be made more compact. In other words, the above-mentioned predetermined thickness can be said to be thinner than the maximum thickness when the metal-air battery 10 expands. In addition, although the rod-shaped parts 21a and 21b are linear in the above example, they may have other shapes such as wavy shapes. Furthermore, although the rod-shaped parts 21a and 21b are restricted between them in the above example, the metal-air battery 10 may be fixed and restricted by one of the rod-shaped parts 21a and 21b.

The metal-air battery 10 may expand as it is discharged. The thickness of the metal-air battery 10 when it is not discharged, that is, the thickness W1 of the metal-air battery 10 at the initial stage (e.g., at the time of creation) when it is not discharged, is smaller than the thickness W2 when it is expanded. When the thickness W2 when it is expanded becomes larger than L1, the metal-air battery 10 forms a curved portion regulated by the regulating member 21. In this way, even if W1 is smaller than L1, when W2 is larger than L1, that is, when the metal-air battery 10 expands and forms a curved portion regulated by the regulating member, the metal-air battery 10 has a curved portion. Furthermore, it can be said that the regulating member 21 contacts a part of the metal-air battery 10 to suppress an increase in the thickness of the part of the metal-air battery 10.

The curved portion 10a is formed, for example, in an area of the exterior body including the first resin film 11, the second resin film 12, and the water-repellent film 16 that contacts the rod-shaped portions 21a and 21b. It is preferable that at least a part of the portion of the rod-shaped portions 21a and 21b that contacts the exterior body is curved. This makes it possible to suppress damage to the exterior body that the rod-shaped portions 21a and 21b contact, particularly the water-repellent film 16. It is preferable that the curved portion 10a is curved in a state in which the first resin film 11, the water-repellent film 16, and the catalyst layer 132 are stacked, and further, it is preferable that the curved portion 10a is curved in a state in which the positive electrode collector 131 and the second storage portion S12 in which the slurry-like negative electrode active material layer 142 is stored are stacked. By previously bending the catalyst layer 132 and/or the positive electrode collector 131 in this way, it is possible to suppress the expansion of the metal-air battery 10 due to discharge. Therefore, it is possible to eliminate unevenness in the discharge reaction in the planar direction of the air electrode 13 caused by a change in the inter-electrode distance due to the expansion of the metal-air battery 10 .

According to the metal-air battery device 1 of this embodiment, the metal-air battery 10 is at least partially restricted by the rod-shaped portions 21a and 21b to a predetermined thickness or less, that is, the distance between the rod-shaped portions 21a and 21b or less, so that even if the negative electrode active material layer 142 or the like expands, the variation in the distance between the positive electrode collector 131 and the negative electrode collector 141 is suppressed. In particular, since the rod-shaped portions 21a and 21b of the restricting member 21 are connected to each other by the connecting portions 21e and 21f, the variation in the distance between the rod-shaped portions 21a and 21b can be further suppressed. This makes the battery reaction in the metal-air battery 10 more uniform, and suppresses the deterioration of battery characteristics such as rate characteristics and battery capacity. In the above, both ends of the rod-shaped portions 21a and 21b are connected by the connecting portions 21e and 21f, but they may be connected by either the connecting portions 21e or the connecting portions 21f.

5, the connecting region 21h in the ring-shaped portion 21g where the rod-shaped portions 21a and 21b of the restricting member 21 are connected to the connecting portions 21e and 21f is configured to have a curved surface. This allows the restricting member 21 to withstand the stress applied thereto when the metal-air battery 10 expands, and prevents the restricting member 21 from being damaged.

The positive electrode collector 131 and the negative electrode collector 141 in the metal-air battery 10 are preferably plate-shaped. Here, the plate-shaped positive electrode collector 131 and the plate-shaped negative electrode collector 141 include those in which the wire-shaped conductive materials constituting the respective ones are arranged, woven, curved, and formed into a plate shape. Furthermore, it is preferable that the positive electrode collector 131 is curved by the rod-shaped parts 21a and 21b of the regulating member 21. This further suppresses the fluctuation of the gap between the positive electrode collector 131 and the negative electrode collector 141, making the battery reaction in the metal-air battery 10 more uniform, and further suppressing the decrease in rate characteristics and battery capacity. The positive electrode collector 131 and the negative electrode collector 141 may be, for example, porous or mesh-shaped. The thickness of the negative electrode collector 141 is not particularly limited, but is preferably thick enough to be curved.

Furthermore, the rod-shaped parts 21a and 21b, for example, restrict the metal-air battery 10 across the central part of the metal-air battery 10 in a direction substantially perpendicular to the stacking direction. Here, substantially perpendicular means 90°±5° to the predetermined direction, and the central part means a region located more than one-quarter of the way from the periphery of the air electrode in a direction substantially perpendicular to the stacking direction (i.e., the surface direction of each component). With this configuration, the metal-air battery 10 can have the first part 10b and the second part 10c in a substantially uniform state, making the battery reaction in the metal-air battery 10 more uniform and further suppressing the deterioration of battery characteristics such as rate characteristics and battery capacity.

In addition, rod-shaped portions 21b and 21c and rod-shaped portions 21c and 21d also have the same effects as rod-shaped portions 21a and 21b.

In addition, when multiple metal-air batteries 10 are attached to the restricting member 21, a gap is provided between adjacent metal-air batteries 10 because the rod-shaped parts are arranged between them. This gap prevents the water-repellent films 16 of the metal-air batteries 10 from coming into contact with each other and blocking the air intake port 111, making it easier to supply air to the metal-air batteries 10.

Furthermore, when multiple metal-air batteries 10 are attached to the restricting member 21, as the metal-air batteries 10 expand, a force is applied to the adjacent metal-air batteries 10 via the rod-shaped portion sandwiched between the adjacent metal-air batteries 10. The applied force causes the adjacent metal-air batteries 10 to be pushed by the rod-shaped portion, suppressing their expansion. This is particularly preferable when multiple metal-air batteries 10 are attached to the restricting member 21, since it is possible to obtain the effect of suppressing the expansion of the multiple metal-air batteries 10 in the same manner. This allows the thickness of each of the multiple metal-air batteries 10 to be approximately uniform, and the battery characteristics such as rate characteristics of each of the multiple metal-air batteries 10 to be uniform, thereby suppressing variation between the metal-air batteries 10.

The metal-air battery device 1 in this embodiment can be easily manufactured by mounting the metal-air battery 10 on the restricting member 21 and storing it in the housing 20. It is preferable that a part of the restricting member 21 is in contact with the housing 20. For example, it is more preferable that the rod-shaped portion 21a of the restricting member 21 arranged between the metal-air battery 10 and the housing 20 is in contact with the housing 20. This makes the thickness of each of the multiple metal-air batteries 10 restricted by the restricting member 21 more uniform. Therefore, it is possible to make the battery characteristics such as the rate characteristics of each of the multiple metal-air batteries 10 contained in the same housing 20 uniform, and it is possible to suppress the variation between the metal-air batteries 10. Furthermore, it is preferable that a hole is provided in the housing 20 in the direction in which the metal-air batteries 10 are arranged and/or in a direction approximately perpendicular to the direction in which the metal-air batteries 10 are arranged. By forming this hole, it becomes easier to supply air to the metal-air battery 10, and it is possible to suppress the deterioration of the battery characteristics. Holes in the casing 20 in a direction approximately perpendicular to the direction in which the metal-air batteries 10 are arranged are preferable as they allow air to flow more easily in a direction parallel to the air intake 111, making it easier to supply air to the metal-air batteries 10.

In addition, it is preferable that the hole in the side wall facing the direction in which the metal-air batteries 10 are arranged in the housing 20, i.e., the direction approximately perpendicular to the stacking direction, is provided so as to face the space between the metal-air batteries 10 formed by the restricting member 21. This makes it possible to easily supply air to each metal-air battery 10. Note that the number of holes in the side wall may be one or more.

Furthermore, in the above, an example was given in which the rod-shaped parts 21a and 21b of the restricting member 21 restrict the center part of the vertical direction of the metal-air battery 10, but the number of restricting members 21 and the parts to be restricted are not limited to this. When restricting the metal-air battery 10 with a plurality of restricting members 21, it is preferable that the restricting parts are parts that divide the air intake 111 of the metal-air battery 10 into approximately equal parts in the vertical and/or horizontal directions. For example, as shown in FIG. 7, when two restricting members 21 are used to restrict only the vertical direction of the air intake 111 of the metal-air battery 10, the two restricting members 21 may restrict a part that divides the air intake 111 of the metal-air battery 10 into approximately three equal parts in the vertical direction, or as shown in FIG. 8, when four restricting members 21 are used to restrict the air intake 111 of the metal-air battery 10 in the vertical and horizontal directions, in addition to the configuration of FIG. 7, a part that divides the air intake 111 of the metal-air battery 10 into approximately three equal parts in the horizontal direction may be restricted. By increasing the number of portions that restrict the metal-air battery 10 using a plurality of restricting members 21, the thickness W1 of the metal-air battery 10 can be restricted more efficiently.

In the above, the restricting member 21 and the housing 20 are provided separately, but they may be configured to be formed integrally. In the metal-air battery device 1 of this embodiment, the housing 20 can be made of a general material such as resin or metal. The restricting member 21 and the housing 20 may be made of the same material or different materials.

<Examples and Comparative Examples>
A metal-air battery having substantially the same configuration as the metal-air battery 10 according to the above embodiment was fabricated in the following manner.

First, a square resin film measuring 110 mm x 110 mm was prepared as the first resin film. The resin film was a laminate of a nylon (registered trademark) film with a thickness of 15 μm and a polyethylene (PE) film with a thickness of 100 μm. An air intake port, which was an opening measuring 60 x 60 mm, was formed in this first resin film.

Next, a water-repellent film made of a 200 μm-thick polytetrafluoroethylene film measuring 70 mm x 70 mm was placed to cover the air intake of the resin film, and was heat-welded to the resin film. The weld width was 2 mm.

Next, a catalyst layer of 70 mm x 70 mm was laminated on the surface opposite to the water-repellent film heat-welded to the resin film. The catalyst layer was a porous body (thickness: 500 μm) containing _MnO2 as an oxygen reduction catalyst, acetylene black as an oxygen reduction catalyst and conductive agent, and polytetrafluoroethylene as a binder.

A 77 mm x 70 mm positive electrode current collector with a lead connected was laminated on top of this catalyst layer. The positive electrode current collector was a 180 μm thick Ni expand. The lead was a 50 x 10 mm, 100 μm thick Ni foil with a tab film attached.

These were then glued together using a press.

Next, a separator was laminated on the positive electrode current collector, and the periphery of the separator was heat-welded to the first resin film and the tab film of the lead. The separator was a polyolefin nonwoven fabric with dimensions of 92 mm x 80 mm and a thickness of 200 μm. The welding width between the separator and the first resin film, and between the separator and the tab film, was 2 mm.

Next, a negative electrode current collector measuring 77 mm x 70 mm was laminated on top of the separator. The negative electrode current collector was a Cu expand having a thickness of 280 μm. The negative electrode current collector had a lead attached to a tab film made of Ni foil measuring 50 mm x 10 mm and having a thickness of 100 μm.

Next, a square resin film of 110 mm x 110 mm similar to the first resin film was laminated on the negative electrode current collector as the second resin film. The first resin film and the second resin film were then heat-welded to each other so that the welding width was 2 mm on three sides except for one side.

Next, the electrolyte and the negative electrode active material were inserted between the separator and the second resin film from the one side where the first resin film and the second resin film were not welded. The electrolyte was a 7M KOH aqueous solution. The negative electrode active material particles were zinc powder. After a predetermined amount of electrolyte and negative electrode active material were inserted, the remaining side between the first resin film and the second resin film was welded. Specifically, the overlapping portion of the first resin film and the second resin film was welded to a weld width of 4 mm.

The metal-air battery produced had a thickness of 8 mm. Metal-air batteries were produced in the same manner.

On the other hand, a 2 mm thick regulating member having the shape shown in FIG. 5 was prepared as the regulating member for each example. The initial thickness W1 of the metal-air battery in each example and the distance between the rod-shaped parts (width of the ring-shaped part) L1 are as shown in Table 1 below. L1 is the same for the three ring-shaped parts. The three metal-air batteries prepared above were attached to the regulating members of each example in the positions shown in FIG. 6 and placed in the housing. The metal-air battery device of each example was prepared by connecting the positive and negative electrodes of adjacent metal-air batteries. ABS resin was used as the material for the regulating member and housing of each example. In Comparative Example 1, a metal-air battery device was prepared by simply connecting three metal-air batteries without using a regulating member.

A discharge capacity test was conducted on the metal-air battery devices of the examples and comparative examples. The discharge test was conducted by connecting the metal-air battery device to a load device and conducting a discharge test in a room temperature environment until the voltage fell below 2.4 V at the discharge rate shown in Table 1. The results are shown in Table 1. The discharge capacity is shown as a relative value with Example 2 set as the reference (100).

In Example 5, L1 was larger than W1 in the initial stage, but the metal-air battery expanded during discharge and was restricted by the restricting member to form a curved portion.

The results shown in Table 1 reveal that the metal-air battery device in the embodiment has a higher discharge capacity at each discharge rate than the metal-air battery device in the comparative example.

The present invention is not limited to the above-described embodiments, and may be replaced with a configuration that is substantially the same as the configuration shown in the above-described embodiments, a configuration that has the same effect, or a configuration that can achieve the same purpose.

Claims (15)

At least two metal-air batteries each having a positive electrode, a negative electrode disposed opposite the positive electrode, and an exterior housing that houses the positive electrode and the negative electrode;
a restricting member that is in contact with the at least two metal-air batteries from the outside and restricts the at least two metal-air batteries to a partial thickness equal to or less than a predetermined thickness , the restricting member being made of resin or metal ;
Equipped with
the at least two metal-air batteries each have a curved portion in which the exterior body is curved inwardly by being restricted by the restricting member,
the regulating member has a plurality of rod-shaped portions that linearly regulate the at least two metal-air batteries in a direction substantially perpendicular to a stacking direction in which the positive electrode and the negative electrode are stacked,
The intervals between the rod-shaped portions in the stacking direction are constant,
One of the rod-shaped portions is disposed between adjacent metal-air batteries of the at least two metal-air batteries.
Metal-air battery device. The metal-air battery device according to claim 1 , wherein the regulating member is provided so as to sandwich the at least two metal-air batteries in a stacking direction in which the positive electrodes and the negative electrodes are stacked. The metal-air battery device according to claim 1 , wherein the regulating member has a connecting portion that connects the plurality of rod-shaped portions to each other. The metal-air battery device according to claim 3 , wherein the regulating member has a ring-shaped portion in which adjacent rod-shaped portions are connected by the connecting portions, and the at least two metal-air batteries are inserted into the ring-shaped portion. The metal-air battery device according to claim 4 , wherein a connecting region in the ring-shaped portion where the plurality of rod-shaped portions and the connecting portion are connected has a curved surface. The metal-air battery device according to any one of claims 1 to 5 , further comprising an electrolyte solution contained inside the exterior body. The metal-air battery device according to any one of claims 1 to 6 , further comprising a separator provided between the positive electrode and the negative electrode. The positive electrode has a plate-shaped positive electrode current collector,
The metal-air battery device according to any one of claims 1 to 7 , wherein the negative electrode has a plate-shaped negative electrode current collector. The metal-air battery device according to any one of claims 1 to 8 , wherein the negative electrode contains a slurry-like negative electrode active material. The positive electrode includes a catalyst layer including a catalyst having oxygen reduction ability,
The metal-air battery device according to any one of claims 1 to 9 , wherein the catalyst layer has a curved portion where the exterior body is curved by being regulated by the regulating member. The metal-air battery device according to any one of claims 1 to 10 , wherein a part of the regulating member that comes into contact with the metal-air battery is a curved surface. The metal-air battery device according to any one of claims 1 to 11 , wherein the exterior body has an opening provided on a surface facing the positive electrode, and has a water-repellent film covering the opening. The metal-air battery device according to claim 12 , wherein the water-repellent film faces the regulating member. The metal-air battery device according to any one of claims 1 to 13 , further comprising a housing that houses the metal-air batteries arranged in a stacking direction in which the positive electrodes and the negative electrodes are stacked. The metal-air battery device according to claim 14 , wherein the housing has side walls opposing each other in a direction substantially perpendicular to the stacking direction, and the side walls are provided with at least one hole through which air within the housing is supplied.

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