JP7487308B2 - Metal-air battery and method for manufacturing the same - Google Patents

Description

The present disclosure relates to a metal-air battery having a positive electrode and a negative electrode and a method for manufacturing the metal-air battery.

In recent years, various metal-air batteries have been proposed in which the positive and negative electrodes are arranged in a laminated manner inside an exterior body. Metallic or resin containers are generally used as the exterior body of metal-air batteries. Laminated metal-air batteries have also been proposed in which the exterior body is made of a laminated packaging material containing a thermoplastic resin, and the electrodes and electrolyte are housed inside the laminated packaging material.

For example, Patent Document 1 discloses this type of metal-air battery in which a negative electrode, separator, air electrode, water-repellent membrane, and air diffusion paper are laminated together and housed together with the electrolyte in an exterior body made of a polymer membrane with hydrogen gas permeability. The exterior body arranged on the air electrode side has an air intake hole, and air diffusion paper is fixed from the inside so as to cover this air intake hole. The water-repellent membrane is arranged on the inside of the air diffusion paper for the purposes of supplying oxygen to the air electrode and preventing leakage of the electrolyte.

JP 2006-19246 A

In the conventional technology, the exterior body having an air intake hole and the air diffusion paper are bonded, but the water-repellent film on the inside is not bonded to the air diffusion paper, and the water-repellent film is not bonded to the exterior body. The air diffusion paper bonded to the exterior body diffuses air but does not have the ability to suppress leakage. Therefore, in addition to the risk of a gap being generated between the exterior body and the water-repellent film, there is also the risk that the electrolyte will move into the gap and reach the air diffusion paper, and furthermore, that the electrolyte will leak out from the air intake hole of the exterior body.

In addition, even if the exterior body and the water-repellent film are welded together, the water-repellent film does not allow the components of the molten polymer film to penetrate the water-repellent film due to the water-repellent properties of the water-repellent film, which can easily cause poor adhesion at the welded interface and lead to leakage of the electrolyte.

When electrolyte leaks, the electrolyte level drops, leaving some electrode parts that are not wetted by the electrolyte, resulting in a decrease in battery capacity. In the case of a secondary battery, the occurrence of electrode parts that are not wetted by the electrolyte can cause current to concentrate in the remaining electrode parts (areas that are wetted by the electrolyte), which can result in a decrease in charge-discharge cycle life.

The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a metal-air battery and a manufacturing method thereof that can suppress leakage of electrolyte and suppress a drop in the electrolyte level.

In order to solve the above-mentioned problems, a first aspect of the present disclosure is a metal-air battery comprising a positive electrode, a negative electrode disposed opposite the positive electrode, an electrolyte disposed at least between the positive electrode and the negative electrode, an exterior body having an opening on a surface facing the positive electrode, and a water-repellent film covering the opening on the inside of the exterior body, wherein the exterior body is made of a resin film, the water-repellent film, the positive electrode, the negative electrode, and the electrolyte are housed inside the exterior body, the water-repellent film is a porous film having a large number of pores, and an adhesive interface of polyolefin resin is provided between the exterior body and the water-repellent film, thereby fixing the water-repellent film to the exterior body.

In the metal-air battery, it is preferable that the exterior body and the water-repellent film are fixed via the adhesive interface at the peripheral portion of the opening.

According to the above aspect, the opening of the exterior body is securely covered with a water-repellent film fixed to the exterior body via an adhesive interface, thereby preventing gaps from occurring between the exterior body and the water-repellent film and suppressing leakage of the electrolyte.

In addition, in order to solve the above-mentioned problems, a second aspect of the present disclosure is a method for manufacturing a metal-air battery comprising a positive electrode, a negative electrode disposed opposite the positive electrode, an electrolyte disposed at least between the positive electrode and the negative electrode, an exterior body formed of a resin film and having an opening on a surface facing the positive electrode, and a water-repellent film covering the opening on the inside of the exterior body, the water-repellent film being a porous film having a large number of pores, and comprising a porous resin layer containing at least one type of polyolefin resin on the surface facing the exterior body, the method including the steps of: placing the water-repellent film on the exterior body facing the opening; and welding the porous resin layer and the exterior body at least at the periphery of the opening, wherein an adhesive interface between the exterior body and the water-repellent film is provided on the porous resin layer, and the water-repellent film is fixed to the exterior body.

According to the above aspect, it is possible to form a good adhesive interface between the exterior body and the water-repellent film, and the water-repellent film can reliably suppress leakage of the electrolyte. In addition, since the water-repellent film has a porous resin layer, it is easy to weld the water-repellent film, which makes it possible to simplify the manufacturing process and reduce costs.

According to the present disclosure, it is possible to produce a metal-air battery that can suppress leakage of electrolyte and prevent the water level of the electrolyte from decreasing.

FIG. 1 is a plan view showing a schematic configuration of a metal-air battery according to a first embodiment of the present disclosure. FIG. 2 is a cross-sectional view taken along line AA in FIG. FIG. 3 is a cross-sectional view showing a schematic enlarged view of the first resin film, the water-repellent film, and the air electrode that constitute the metal-air battery. FIG. 4A is an enlarged cross-sectional view showing a portion M in FIG. FIG. 4B is an enlarged cross-sectional view showing another example corresponding to the portion M in FIG. FIG. 5A is a plan view that illustrates a configuration example of a porous resin layer and an adhesive interface of a water-repellent film in the metal-air battery. FIG. 5B is a cross-sectional view taken along line BB of FIG. 5A. FIG. 6A is a plan view that illustrates another example of the structure of the porous resin layer and the adhesive interface of the water-repellent film in the metal-air battery. FIG. 6B is a cross-sectional view taken along line CC of FIG. 6A. FIG. 7A is a plan view that illustrates a configuration example of a porous resin layer and an adhesive interface of a water-repellent film of a metal-air battery according to embodiment 2 of the present disclosure. FIG. 7B is a cross-sectional view taken along line DD of FIG. 7A. FIG. 8A is a plan view showing a schematic diagram of another example of the structure of the porous resin layer and the adhesive interface of the water-repellent film of the metal-air battery. FIG. 8B is a cross-sectional view taken along line EE of FIG. 8A. FIG. 9A is a plan view that illustrates a configuration example of a porous resin layer and an adhesive interface of a water-repellent film of a metal-air battery according to embodiment 3 of the present disclosure. FIG. 9B is a cross-sectional view taken along line FF of FIG. 9A. FIG. 10A is a plan view showing a schematic diagram of another example of the structure of the porous resin layer and the adhesive interface of the water-repellent film in the metal-air battery. FIG. 10B is a cross-sectional view taken along line GG of FIG. 10A. FIG. 11 is a plan view showing a schematic configuration of a metal-air battery according to embodiment 4 of the present disclosure. FIG. 12 is a cross-sectional view taken along line HH of FIG.

Below, the metal-air battery and its manufacturing method relating to an embodiment of the present disclosure are described in detail with reference to the drawings.

(Embodiment 1)
FIG. 1 is a plan view showing a schematic configuration of a metal-air battery 10 according to the first embodiment, and FIG. 2 is a cross-sectional view taken along the line AA in FIG.

As shown in the figure, the metal-air battery 10 has a battery case (exterior body) 13 formed by bonding a first resin film 11 and a second resin film 12. The battery case 13 contains an air electrode 15, a metal negative electrode 16, a separator 18, and a water-repellent film 14. The battery case 13 is also filled with an electrolyte (not shown). The first resin film 11 and the second resin film 12 are formed from a common resin film that can be welded.

The separator 18 is disposed opposite the first resin film 11, and the peripheral portion of the separator 18 is bonded to the peripheral portion of the first resin film 11. The air electrode 15 and the water-repellent film 14 are housed between the first resin film 11 and the separator 18.

The first resin film 11 is provided with one air intake port 111 as an opening for taking in air, and a water-repellent film 14 is adhered to this air intake port 111. The air electrode 15 is disposed between the water-repellent film 14 and the separator 18. Details of the air intake port 111 and the water-repellent film 14 will be described later.

The second resin film 12 is disposed opposite the first resin film 11, facing the separator 18. The peripheral portion of the second resin film 12 is bonded to the peripheral portion of the separator 18. It is preferable that the peripheral portion of the second resin film 12 is also bonded to the peripheral portion of the first resin film 11. A metal negative electrode 16 is housed between the second resin film 12 and the separator 18.

The air electrode 15 is a positive electrode having oxygen reduction and oxygen generation capabilities, and includes a current collector 151 and a catalyst layer 152 in contact with the current collector 151. A portion of the current collector 151 extends outside the exterior body and serves as a lead portion 153 of the metal-air battery 10. There are no particular limitations on the material of the current collector 151, so long as it is a material commonly used in the field of metal-air batteries. The thickness of the current collector 151 is preferably 0.05 mm to 0.5 mm.

The catalyst layer 152 includes at least an air electrode catalyst. The air electrode catalyst is a catalyst that has 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, metal oxides, metal hydroxides, and metal sulfides, and one or more of these can be used.

This allows a three-phase interface in which oxygen gas, water, and electrons coexist to be formed on the air electrode catalyst, allowing the discharge reaction to proceed. When the metal-air battery 10 is a primary battery, the catalyst layer 152 can contain a catalyst such as manganese dioxide. When the metal-air battery 10 is a secondary battery, the catalyst layer 152 may contain not only an air electrode catalyst having oxygen reduction ability, but also a catalyst having oxygen generation ability, or may have both oxygen generation ability and oxygen reduction ability. The thickness of the catalyst layer 152 is preferably 0.1 mm or more and 1.0 mm or less.

The metal negative electrode 16 is housed between the second resin film 12 and the separator 18 in a state where the active material layer 162 is laminated on the current collector 161. The current collector 161 and particulate negative electrode active material (e.g., zinc or zinc oxide) may be added separately and laminated. The metal negative electrode 16 may also contain the current collector 161 and a colloidal slurry in which particles of the negative electrode active material and an electrolyte are mixed. The slurry preferably has a ratio of the weight of the electrolyte to the weight of the negative electrode active material of 0.3 to 2.0.

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 zinc, cadmium, lithium, sodium, magnesium, lead, tin, aluminum, and iron can be used as the negative electrode active material. The negative electrode active material is reduced by charging, so it may be in the form of a metal oxide.

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 average particle diameter can be measured using a particle size distribution measuring device.

A portion of the current collector 161 extends outside the exterior body to form the lead portion 163 of the metal-air battery 10. The thickness of the current collector 161 is preferably 0.05 mm to 0.50 mm. The thickness of the active material layer 162 is preferably 1.0 mm to 10.0 mm.

In addition, in the metal-air battery 10, the air electrode 15, the metal negative electrode 16, the separator 18, and the electrolyte can all be those that have been conventionally used in the fields of laminated batteries and metal-air batteries.

The resin films constituting the first resin film 11 and the second resin film 12 are preferably formed from a thermoplastic resin material with excellent alkali resistance, and more preferably have a multi-layer structure in which multiple resin films are laminated. Examples of the thermoplastic resin material constituting such a resin film include polyolefin-based resins such as polypropylene and polyethylene. In addition, when the first resin film 11 has a multi-layer structure, it is preferable that at least the surface of the first resin film 11 facing the water-repellent film 14 is a resin film layer containing a polyolefin-based resin. Polyolefin-based resin is a general term for polymers synthesized using alkenes as monomers.

The first resin film 11 has a generally rectangular air intake port 111 that penetrates both the front and back surfaces (inside and outside the battery case 13) and is provided in the approximate center as an opening for taking in air. As shown in Figure 2, the water-repellent film 14 is arranged so as to cover this air intake port 111 from the inside.

Figure 3 is a cross-sectional view showing a schematic enlargement of the first resin film 11, the water-repellent film 14, and the air electrode (positive electrode) 15 that constitute the metal-air battery 10. Figures 4A and 4B are enlarged cross-sectional views of part M in Figure 3.

3, the first resin film 11 has a water-repellent film 14 disposed thereon to cover the air intake 111 in order to supply air (oxygen) to the air electrode 15 and to prevent the electrolyte in the battery case 13 (e.g., inside the first resin film 11) from leaking from the air intake 111. The air electrode 15 (and separator 18) are layered on the water-repellent film 14.

The first resin film 11 is provided with one rectangular air intake port 111 as an opening penetrating the inside and outside of the battery case 13. The water-repellent film 14 has a rectangular shape with an outer shape larger than the air intake port 111. The water-repellent film 14 is arranged so as to overlap the air intake port 111 from the inside of the battery case 13.

The water-repellent film 14 is a film that is water-repellent but allows air to pass through. In the illustrated embodiment, the water-repellent film 14 is a porous film having a large number of pores and has a gas-liquid separation function. The material of the water-repellent film 14 is a material that is commonly used in the field of metal-air batteries and can be fixed to the first resin film 11. Specific examples of the water-repellent film 14 include a film (such as a microporous film) made of a fluorine-containing resin such as PTFE (polytetrafluoroethylene).

At the periphery of the air intake 111, as shown in an enlarged view in FIG. 4A, the first resin film 11 and the water-repellent film 14 are fixed via an adhesive interface 143. As shown in the figure, the water-repellent film 14 has a large number of pores 140. On the side of the water-repellent film 14 facing the first resin film 11, an adhesive interface 143 of a welding resin 142 containing at least one type of polyolefin resin is formed. This causes the water-repellent film 14 to be adhered to the first resin film 11. The adhesive interface 143 is formed by embedding the welding resin 142 in the surface layer of the pores 140 of the water-repellent film 14. This welding resin 142 is formed by containing a polyolefin resin.

4B, the water-repellent film 14 may be configured with a porous resin layer 141 on the surface layer that contacts the first resin film 11, and is laminated and bonded to the first resin film 11 so as to face the air intake port 111 and cover it. The polyolefin resin (welded resin 142) that constitutes the molten porous resin layer 141 penetrates the pores 140 of the water-repellent film 14 and solidifies, thereby providing an adhesive interface 143 between the water-repellent film 14 and the first resin film 11.

In this way, the water-repellent film 14 and the first resin film 11 are bonded together via the adhesive interface 143, and the water-repellent film 14 is fixed to the first resin film 11. The means for bonding the first resin film 11 and the water-repellent film 14 is preferably thermal welding.

A more preferred embodiment of the polyolefin resin (welding resin 142) placed between the first resin film 11 and the water-repellent film 14 is shown below.

For example, a porous resin layer 141 containing a polyolefin resin may be provided integrally with the surface layer of the water-repellent film 14. Alternatively, a nonwoven fabric made of a polyolefin resin may be welded to the surface of the water-repellent film 14 as the porous resin layer 141, and may be provided integrally with the water-repellent film 14.

Figure 5A is a plan view showing a schematic configuration example of the porous resin layer 141 and adhesive interface 143 of the water-repellent film 14, and Figure 5B is a cross-sectional view taken along the line B-B of Figure 5A. As shown in Figure 5A, the adhesive interface 143 between the first resin film 11 and the water-repellent film 14 is provided at a predetermined width outward from the opening edge of the air intake 111 of the first resin film 11. Also, as shown in Figure 5B, a porous resin layer 141 is provided over the entire upper surface of the water-repellent film 14. The porous resin layer 141 is disposed on the surface facing the first resin film 11, and the first resin film 11 and the water-repellent film 14 are fixed via the adhesive interface 143.

In the illustrated embodiment, the water-repellent film 14 and the porous resin layer 141 provided in the water-repellent film 14 have an area larger than the opening area of the air intake 111. Therefore, the porous resin layer 141 is configured to have an area that sufficiently overlaps the air intake 111 of the first resin film 11. The first resin film 11 and the porous resin layer 141 are welded over the entire overlapping area, thereby providing an adhesive interface 143 of polyolefin resin between the first resin film 11 and the water-repellent film 14. The adhesive interface 143 is continuously formed in a rectangular shape along the four periphery of the air intake 111.

The first resin film 11 and the porous resin layer 141 may be configured to be welded to each other in a portion of the overlapping area. Figure 6A is a plan view showing a schematic diagram of another configuration example of the porous resin layer 141 and adhesive interface 143 of the water-repellent film 14, and Figure 6B is a cross-sectional view taken along C-C in Figure 5A. As shown in Figure 6A, the water-repellent film 14 and the porous resin layer 141 have an area larger than the opening area of the air intake 111. Also, as shown in Figure 6B, the porous resin layer 141 is provided on the entire upper surface of the water-repellent film 14.

In this embodiment, similar to the case of FIG. 5A, the first resin film 11 and the water-repellent film 14 are arranged in an overlapping state, and only the areas to be welded are different. That is, as shown in FIG. 6A and FIG. 6B, the adhesive interface 143 is formed by welding in a part of the overlapping area of the first resin film 11 and the porous resin layer 141. The adhesive interface 143 is continuously formed in a rectangular shape along the four periphery of the air intake 111, and is provided outside the air intake 111. The water-repellent film 14 covers the entire air intake 111, and is fixed to the first resin film 11 via the adhesive interface 143.

The thickness of the water-repellent film 14 is preferably, for example, 0.05 mm to 0.5 mm, while the porous resin layer 141 is preferably 50 μm to 150 μm. If the thickness of the porous resin layer 141 is less than 50 μm, the welding resin 142 does not easily penetrate into the pores 140 of the water-repellent film 14, and sufficient welding is not achieved, resulting in insufficient adhesive strength. If the thickness of the porous resin layer 141 exceeds 150 μm, it becomes difficult to melt the entire thickness of the porous resin layer 141, and there is a risk of leaving unwelded porous portions, which may cause the electrolyte to leak out.

In addition, it is preferable that the porosity of the porous resin layer 141 is 65% or more and 90% or less. If the porosity is less than 65%, the gas permeability is low, which may inhibit the battery reaction and deteriorate the battery characteristics. In addition, if the porosity is more than 90%, the welding resin 142 that has permeated into the pores 140 of the water-repellent film 14 may not solidify sufficiently.

The porosity of the water-repellent film 14 is preferably 20% or more and 60% or less. If the porosity of the water-repellent film 14 is less than 20%, the gas permeability may decrease due to the penetration and solidification of the polyolefin resin into the pores 140 of the water-repellent film 14. In addition, if the porosity of the water-repellent film 14 exceeds 60%, the water repellency and leakage resistance of the water-repellent film 14 may decrease.

It is preferable that the polyolefin-based resins contained in the first resin film 11 and the porous resin layer 141 each contain the same type of first polyolefin-based resin. By containing the same type of polyolefin-based resin, the resins are compatible with each other at the adhesive interface 143 and are firmly bonded to each other.

In addition, the porous resin layer 141 may further include a second polyolefin resin different from the first polyolefin resin. The first polyolefin resins included in both the first resin film 11 and the porous resin layer 141 are compatible with each other to obtain strong adhesion, while the porous resin layer 141 contains the second polyolefin resin, which allows the porous resin layer 141 to maintain its strength, thereby suppressing dimensional changes in the porous resin layer 141 during welding, etc.

Furthermore, in the above case, the porous resin layer 141 may be formed of fibers having a core-shell structure with the first polyolefin resin as the shell and the second polyolefin resin as the core. With this configuration, when the water-repellent film 14 and the porous resin layer 141 are welded together, the core layer made of the second polyolefin resin maintains its shape, and the pores of the porous resin layer 141 can be prevented from being blocked by the melting of the first polyolefin resin.

It is preferable that the melting point of the second polyolefin resin is higher than that of the first polyolefin resin, for example, 20 to 70° C. higher. For example, the first polyolefin resin is polyethylene, and the second polyolefin resin is polypropylene.

By being configured in this manner, the metal-air battery 10 has the first resin film 11 having the air intake 111 of the battery case 13 and the water-repellent film 14 blocking the air intake 111 bonded well via the adhesive interface 143, and is fixed without creating any gaps between the first resin film 11 and the water-repellent film 14. This prevents the water level of the electrolyte in the metal-air battery 10 from decreasing, and prevents a decrease in battery capacity.

(Method of manufacturing metal-air battery)
In the manufacturing method of the metal-air battery 10 according to the first embodiment, first, the water-repellent film 14 is laminated on the first resin film 11 having the air intake 111. The water-repellent film 14 is arranged so that the porous resin layer 141 faces the air intake 111. As shown in Fig. 5A to Fig. 6B, the entire or part of the overlapping area of the porous resin layer 141 and the first resin film 11 at the peripheral portion of the air intake 111 is welded continuously around the four sides, and the water-repellent film 26 is bonded to the first resin film 21. As a result, an adhesive interface 143 of the welded resin 142 is provided between the first resin film 11 and the water-repellent film 14, and the water-repellent film 14 is fixed to the first resin film 11.

Next, the catalyst layer 152 of the air electrode 15 and the current collector 151 are laminated on the water-repellent film 14, and these are pressed together by a press. Furthermore, the separator 18 is laminated on the current collector 151, and the separator 18 is welded to the first resin film 11. As shown in FIG. 2, the separator 18 has an area larger than the water-repellent film 14, and the overlapping portion of the separator 18 and the first resin film 11 are welded together. Here, it is preferable that the area ratio of the separator 18 to the area of the first resin film 11, including the opening area of the air intake 111, is 0.55 to 0.95.

Next, the current collector 161 of the metal negative electrode 16 is laminated on the separator 18. Furthermore, the second resin film 22 is laminated so as to face the current collector 161, and each of the three sides except the bottom side is adhered. At this time, at least the overlapping portions of the resin films (the first resin film 11 and the second resin film 22) are welded on the two side sides. At least the overlapping portions of the first resin film 11, the second resin film 22, and the separator 18 are welded on the top side.

Zinc powder and electrolyte are then poured in through the opening on one side (the bottom side) that is not welded, and that side is then glued. Because the separator 18 is already glued to the first resin film 11, the poured in zinc powder does not get into the space between the first resin film 11 and the separator 18. At the bottom side, the overlapping portion of the first resin film 11 and the second resin film 22 is welded. The electrolyte permeates through the separator 18 to the air electrode 15.

In the manufacturing method of the metal-air battery 10 described above, the water-repellent film 14 is provided with a porous resin layer 141, and the porous resin layer 141 and the first resin film 11 are welded together to reliably provide an adhesive interface 143 between them. In addition, since the separator 18 is bonded to the first resin film 11 that constitutes the battery case 13, the metal-air battery 10 can be easily assembled by laminating and bonding the components. This makes it possible to simplify the manufacturing process and reduce costs.

(Embodiment 2)
7A and 7B are schematic diagrams showing an example of the configuration of the first resin film 11 and the water-repellent film 14 in the metal-air battery 10 according to the second embodiment of the present disclosure, where FIG. 7A is a plan view and FIG. 7B is a cross-sectional view taken along the line D-D of FIG. 7A.

In the embodiment described below, the basic configuration of the metal-air battery is the same as in embodiment 1, so the different configurations will be described in detail, and the other configurations will be omitted and will use the same symbols as in embodiment 1.

In the first embodiment, the water-repellent film 14 is configured to have a porous resin layer 141 on the entire upper surface, which is the surface facing the first resin film 11. The porous resin layer 141 is not limited to being provided on the entire upper surface of the water-repellent film 14, and may be provided on only a portion of the upper surface of the water-repellent film 14.

7B, the water-repellent film 14 is disposed so as to cover the entire air intake 111 of the first resin film 11, while the water-repellent film 14 is provided with a porous resin layer 141 on the outer periphery of the upper surface. The porous resin layer 141 of the water-repellent film 14 is provided so as to have an area that overlaps with the first resin film 11, and does not have to cover the entire air intake 111. For example, when the porous resin layer 141 is made of a nonwoven fabric made of a polyolefin resin, the porous resin layer 141 may be provided with an opening having an area smaller than the air intake 111.

As shown in Figure 7A, the adhesive interface 143 between the first resin film 11 and the water-repellent film 14 is provided at a predetermined width outward from the opening edge of the air intake 111 of the first resin film 11. Also, as shown in Figure 7B, a porous resin layer 141 is disposed on the surface facing the first resin film 11, and the first resin film 11 and the water-repellent film 14 are fixed via the adhesive interface 143.

Such a first resin film 11 and porous resin layer 141 may be configured to be welded to each other in a portion of the overlapping area. Figure 8A is a plan view showing a schematic diagram of another example of the configuration of the porous resin layer 141 and the adhesive interface 143 of the water-repellent film 14, and Figure 8B is a cross-sectional view taken along line E-E of Figure 5A.

As shown in the figure, the water-repellent film 14 has a porous resin layer 141 on the outer periphery of the upper surface, and has an opening with an area smaller than the air intake 111. The water-repellent film 14 is layered so that the porous resin layer 141 is disposed on the surface facing the first resin film 11, and the first resin film 11 and the porous resin layer 141 are welded together in a portion of the overlapping area to form an adhesive interface 143. The adhesive interface 143 is continuously formed in a rectangular shape along the four periphery of the air intake 111, and is provided outside the air intake 111. The water-repellent film 14 covers the entire air intake 111, and is fixed to the first resin film 11 via the adhesive interface 143.

In the metal-air battery 10 according to this embodiment, the first resin film 11 having the air intake 111 and the water-repellent film 14 blocking the air intake 111 are well bonded via the adhesive interface 143, and it is possible to prevent a gap from being formed between the first resin film 11 and the water-repellent film 14. This makes it possible to suppress a decrease in the water level of the electrolyte and a decrease in the battery capacity.

(Embodiment 3)
9A and 9B are schematic diagrams showing an example of the configuration of the first resin film 11 and the water-repellent film 14 in the metal-air battery 10 according to the third embodiment of the present disclosure, where FIG. 9A is a plan view and FIG. 9B is a cross-sectional view taken along the line F-F of FIG. 9A.

In the first and second embodiments, the first resin film 11 is configured to have one rectangular air intake 111. The first resin film 11 is not limited to having one air intake, and may have multiple air intakes.

For example, as shown in Fig. 9A, the first resin film 11 may be provided with a plurality of circular air intakes 112. Also, as shown in Fig. 9B, the water-repellent film 14 has a porous resin layer 141 provided over the entire upper surface. The porous resin layer 141 is disposed on the surface facing the first resin film 11, and the first resin film 11 and the water-repellent film 14 are fixed together via an adhesive interface 143.

In the illustrated embodiment, the water-repellent film 14 and the porous resin layer 141 provided in the water-repellent film 14 have an area covering all of the plurality of air intake ports 112. Therefore, the porous resin layer 141 has an area that sufficiently overlaps the plurality of air intake ports 112 of the first resin film 11. The first resin film 11 and the porous resin layer 141 are welded over the entire overlapping area, thereby providing an adhesive interface 143 of polyolefin resin between the first resin film 11 and the water-repellent film 14.

In this embodiment, the first resin film 11 and the porous resin layer 141 may be welded to each other in a part of the overlapping area, as in the above embodiment. FIG. 10A is a plan view showing another example of the configuration of the porous resin layer 141 and the adhesive interface 143 of the water-repellent film 14 in embodiment 3, and FIG. 10B is a cross-sectional view taken along the line G-G of FIG. 10A. As shown in the figure, the porous resin layer 141 is provided on the entire upper surface of the water-repellent film 14, while the adhesive interface 143 is formed by welding to a part of the overlapping area of the first resin film 11 and the porous resin layer 141. In this case, the adhesive interface 143 is formed in a rectangular shape along the outer periphery of the water-repellent film 14. As shown in FIG. 10A, the adhesive interface 143 is continuously formed in a rectangular shape outside the area where the multiple air intakes 112 are provided. The water-repellent film 14 is arranged to cover all the air intakes 112 and is fixed to the first resin film 11 via the adhesive interface 143.

In the metal-air battery 10 according to this embodiment, the first resin film 11 having a plurality of air intakes 112 and the water-repellent film 14 blocking the air intakes 111 are well bonded via the adhesive interface 143, and the formation of gaps between the first resin film 11 and the water-repellent film 14 is avoided. This prevents the electrolyte water level from decreasing, and thus prevents the battery capacity from decreasing.

(Embodiment 4)
In the above embodiment, a configuration in which the present disclosure is applied to a primary battery (or a two-electrode secondary battery) is disclosed, but in embodiment 4, a suitable configuration in which the present disclosure is applied to a three-electrode secondary battery having two positive electrodes (a first positive electrode and a second positive electrode) and a metal negative electrode between the two positive electrodes is described. In addition, in the following description, an example is given in which the present disclosure is applied to a three-electrode metal-air secondary battery having a metal negative electrode and an air electrode and a charging electrode as two positive electrodes, but the configuration of the present disclosure can also be applied to a metal-air battery having two air electrodes and a metal negative electrode between the two air electrodes.

Figure 11 is a plan view showing the schematic configuration of a metal-air battery 20 according to embodiment 4, and Figure 12 is a cross-sectional view taken along the line H-H in Figure 11. This metal-air battery 20 is characterized in that it is a three-electrode type, and the configuration of the adhesive interface formed by the welding resin can be the same as in embodiments 1 to 3.

11, the metal-air battery 20 is configured by bonding a first resin film 21 and a second resin film 12 together to form a battery case (exterior body) 23, and includes an air electrode (first positive electrode) 25, a metal negative electrode 26, a charging electrode (second positive electrode) 27, a first separator 281, a second separator 282, a first water-repellent film 241, and a second water-repellent film 242 inside the battery case 23. The inside of the battery case 23 is also filled with an electrolyte (not shown).

The first separator 281 is disposed opposite the first resin film 21, and the peripheral portion of the first separator 281 is adhered to the peripheral portion of the first resin film 21. The air electrode 25 and the first water-repellent film 241 are housed between the first resin film 21 and the first separator 281. The first resin film 21 has an air intake port 211 formed as an opening for taking in air, and the first water-repellent film 241 is welded to the first resin film 21 so as to cover the air intake port 211.

The air electrode 25 is disposed between the first water-repellent film 241 and the first separator 281. The thickness of the first separator 281 is preferably 0.05 mm to 0.40 mm. The thickness of the first water-repellent film 241 is preferably 0.05 mm to 0.50 mm.

The second separator 282 is disposed opposite the second resin film 22, and the peripheral portion of the second separator 282 is adhered to the peripheral portion of the second resin film 22. The charging electrode 27 and the second water-repellent film 242 are housed between the second resin film 22 and the second separator 282. The second resin film 22 has an air release port 221 formed as an opening for releasing air, and the second water-repellent film 242 is welded to the second resin film 22 so as to cover the air release port 221.

The charging electrode 27 is disposed between the second water-repellent film 242 and the second separator 282. The thickness of the second separator 282 is preferably 0.05 mm to 0.40 mm. The thickness of the second water-repellent film 242 is preferably 0.05 mm to 0.50 mm.

The first separator 281 and the second separator 282 are arranged opposite each other, and the peripheral portions of the first separator 281 and the second separator 282 are bonded together by heat welding, ultrasonic welding, or the like. That is, the first separator 281 and the second separator 282 whose peripheral portions are bonded together form a bag-shaped separator, and the peripheral portion of the bag-shaped separator is fixed to the exterior body. It is also preferable that the peripheral portions of the first resin film 21 and the second resin film 22 are also bonded together. A metal negative electrode 26 is housed between the first separator 281 and the second separator 282 (inside the bag-shaped separator).

Although the peripheral portions of the first separator 281 and the second separator 282 are bonded together to form a bag-shaped separator, strictly speaking, it is sufficient that the peripheral portion of the first separator 281 is bonded to the peripheral portion of the first resin film 21, and the peripheral portion of the second separator 282 is bonded to the peripheral portion of the second resin film 22.

In the metal-air battery 20 according to this embodiment, the first water-repellent film 241 and the second water-repellent film 242 are provided to prevent leakage of electrolyte from the openings, the air inlet 211 and the air outlet 221, and have a gas-liquid separation function, and adhesive interfaces of fused resin are provided between the first water-repellent film 241 and the first resin film 21, and between the second water-repellent film 242 and the second resin film 22, as in the above embodiment. The first water-repellent film 241 and the second water-repellent film 242 may have a porous resin layer provided on the entire upper surface thereof, or may have a porous resin layer provided on only a portion of the upper surface thereof.

The air electrode 25 is composed of a current collector 251 and a catalyst layer 252, and can be configured similarly to the air electrode 15 shown in the above embodiment. The charging electrode 27 is composed of a current collector 271 and a catalyst layer 272. The catalyst layer 272 may include, for example, a conductive porous carrier and a charging electrode catalyst supported on the porous carrier. This charging electrode catalyst is a catalyst (such as nickel) that has oxygen generating ability, and promotes a charging reaction when the metal-air battery 20 is charged. The catalyst layer 272 is made of, for example, foamed nickel. Parts of the current collectors 251 and 271 extend outside the battery case 23 and become the lead parts 253 and 273 of the metal-air battery 20.

The metal negative electrode 26 has a configuration in which an active material layer 262 is laminated on a current collector 261, and can have a configuration similar to that of the metal negative electrode 16 in embodiment 1. A portion of the current collector 261 extends outside the battery case 23 and serves as a lead portion 263 of the metal-air battery 20.

In the metal-air battery 20 according to this embodiment, as in the first to third embodiments, at least between the first resin film 21 and the first water-repellent film 241 of the battery case 23, and between the second resin film 22 and the second water-repellent film 242, an adhesive interface (143) of the welded resin (142) is provided as shown in FIG. 4A and FIG. 4B. This allows the first resin film 21 and the first water-repellent film 241, and the second resin film 22 and the second water-repellent film 242 to be bonded and fixed. The air intake 211 provided in the first resin film 21 and the air release 221 provided in the second resin film 22 may be one or more, and the shape is not limited to a rectangular shape but may be a circular shape (see FIG. 9A, etc.).

In addition, in the first resin film 21, the first resin film 21 and the porous resin layer of the first water-repellent film 241 may be welded to each other over the entire overlapping area (see Figs. 5A and 7A), providing an adhesive interface of polyolefin resin between the first resin film 21 and the first water-repellent film 241, or may be welded to each other over a portion of the overlapping area to provide an adhesive interface (see Figs. 6A and 8A). The same applies to the second resin film 22 and the second water-repellent film 242.

As a result, even in a three-electrode metal-air battery 20, similar to the metal-air battery 10 shown in embodiments 1 to 3, the first resin film 21 and the first water-repellent film 241 of the battery case 23, and the second resin film 22 and the second water-repellent film 242 are well adhered to each other, making it possible to suppress leakage of electrolyte and improve battery performance.

The present invention can be implemented in various other forms without departing from its spirit or main characteristics. The embodiments disclosed herein are illustrative in all respects and are not intended to be a basis for a restrictive interpretation. Therefore, the technical scope of the present disclosure should not be interpreted solely by the above-described embodiments, but should be defined based on the claims. Furthermore, all modifications within the meaning and scope equivalent to the claims are included.

This application claims priority based on Japanese Patent Application No. 2020-119406, filed on July 10, 2020, the entire contents of which are incorporated herein by reference.

10, 20 Metal-air battery 11, 21 First resin film 111, 112, 211 Air intake port (opening)
12, 22 Second resin film 221 Air release port (opening)
13, 23 Battery case (exterior body)
14 Water-repellent film 140 Pore 141 Porous resin layer 142 Welded resin 143 Adhesive interface 241 First water-repellent film 242 Second water-repellent film 15, 25 Air electrode (positive electrode)
151, 251 Current collector 152, 252 Catalyst layer 153, 253 Lead portion 16, 26 Metal negative electrode (negative electrode)
161, 261 Current collector 162, 262 Active material layer 163, 263 Lead portion 27 Charge electrode (positive electrode)
271 Current collector 272 Catalyst layer 273 Lead portion 18 Separator 281 First separator 282 Second separator

Claims (13)

A positive electrode and
a negative electrode disposed opposite the positive electrode;
an electrolyte disposed between at least the positive electrode and the negative electrode;
an exterior body having an opening on a surface facing the positive electrode;
A metal-air battery comprising a water-repellent film covering the opening on the inside of the exterior body,
the exterior body is made of a resin film, the water-repellent film, the positive electrode, the negative electrode, and the electrolyte are accommodated inside the exterior body, and the water-repellent film is a porous film having a large number of pores;
an adhesive interface of a polyolefin resin is provided between the exterior body and the water-repellent film, and the water-repellent film is fixed to the exterior body ;
the water-repellent film has a porous resin layer containing the polyolefin resin on a surface facing the exterior body,
The metal-air battery is characterized in that the porous resin layer has an outer shell containing a first polyolefin-based resin, and a core that is partially covered by the shell and contains a second polyolefin-based resin having a melting point higher than that of the first polyolefin-based resin . The metal-air battery according to claim 1,
The metal-air battery is characterized in that the exterior body and the water-repellent film are fixed to each other via the adhesive interface at the peripheral portion of the opening. The metal-air battery according to claim 1,
The metal-air battery is characterized in that the resin film contains at least one type of polyolefin resin. The metal-air battery according to claim 1,
The polyolefin resin comprises at least two kinds of polyolefin resins. The metal-air battery according to claim 1,
The metal-air battery is characterized in that the adhesive interface is formed by embedding the polyolefin resin in the pores of the water-repellent film. The metal-air battery according to claim 1 ,
The metal-air battery, wherein the porous resin layer has an area overlapping the opening. The metal-air battery according to claim 1 ,
The metal-air battery, wherein the porous resin layer is a layer containing a nonwoven fabric made of a polyolefin resin. The metal-air battery according to claim 1 ,
The metal-air battery, characterized in that the resin film and the porous resin layer contain the same polyolefin-based resin. The metal-air battery according to claim 1 ,
A metal-air battery, characterized in that the porous resin layer contains at least two types of polyolefin resins. The metal-air battery according to claim 9 ,
The metal-air battery, wherein the porous resin layer contains at least one polyolefin resin different from the resin film. The metal-air battery according to claim 1 ,
The metal-air battery is characterized in that the porous resin layer has a film thickness of 50 μm to 150 μm. The metal-air battery according to claim 1 ,
The metal-air battery is characterized in that the porous resin layer has a porosity of 65% or more and 90% or less. The metal-air battery according to claim 1 ,
The exterior body has a multi-layer structure in which a plurality of resin films are laminated,
A metal-air battery, characterized in that the surface of the exterior body facing the water-repellent film is made of a resin film layer containing the polyolefin resin.

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