Air battery

Abstract

This air battery comprises an air electrode, a metal electrode, an electrolyte, and an oxygen-permeable film in contact with the air electrode. The metal electrode is disposed around the air electrode and the electrolyte.

Description

Air battery

[0001] The present disclosure relates to an air battery.

[0002] Conventionally, an air battery including a metal electrode (negative electrode) using a metal such as zinc as an active material and an air electrode (positive electrode) using oxygen in the air as an active material has been known. Patent Document 1 describes an air battery using a hollow fiber membrane for the water-repellent film of the air electrode. In the air battery described in Patent Document 1, by using a hollow fiber membrane for the water-repellent film of the air electrode, even if the electrolyte leaks, the electrolyte is retained inside the hollow fiber membrane and prevented from leaking to the outside. Further, in the air battery described in Patent Document 1, the air electrode is installed so as to surround the metal electrode, and the periphery of the air electrode is covered with a metal exterior can.

[0003] Japanese Patent Laid-Open No. 05-047388

[0004] The air battery described in Patent Document 1 has a complicated structure in which the metal electrode is surrounded by the air electrode and the air electrode is further surrounded by a metal exterior can, and thus there are limitations in weight reduction and miniaturization.

[0005] Therefore, an object of the present disclosure is to provide an air battery that can be reduced in weight and size.

[0006] [1] The air battery according to the present disclosure includes an air electrode, a metal electrode, an electrolyte, and a film permeable to oxygen that is in contact with the air electrode, and the metal electrode is disposed around the air electrode and the electrolyte.

[0007] In this air battery, since the film permeable to oxygen is in contact with the air electrode, oxygen in the air can be supplied to the air electrode through the film. And since the metal electrode is disposed around the air electrode and the electrolyte, the metal electrode can function as a case for housing the air electrode and the electrolyte. Thereby, it can be used as an air battery without including the metal exterior can described in Patent Document 1. As a result, weight reduction and miniaturization can be achieved.

[0008] [2] In the air battery described in [1], the metal electrode may contain the air electrode and the electrolyte. In this air battery, since the metal electrode contains the air electrode and the electrolyte, it can be used as an air battery even without the metal casing described in Patent Document 1. This makes it possible to reduce weight and size.

[0009] [3] In the air battery described in [1] or [2], the metal electrode may form at least a part of the outer casing material of the air battery. In this air battery, since the metal electrode forms at least a part of the outer casing material of the air battery, it is possible to reduce the weight and size.

[0010] [4] In the air battery described in any of [1] to [3], the metal electrode has an opening, and the air electrode may be exposed from the metal electrode at the opening. In this air battery, since the air electrode is exposed from the metal electrode at the opening of the metal electrode, the air electrode can also be used as the positive terminal.

[0011] [5] The air battery described in [4] may further include an insulator that is placed between the air electrode and the metal electrode to close the opening. In this air battery, since an insulator is placed between the air electrode and the metal electrode to close the opening of the metal electrode, leakage of the electrolyte from the opening can be suppressed and the air electrode and the metal electrode can be insulated.

[0012] [6] In the air battery described in any of [1] to [3], a current collector is further provided in contact with the air electrode, the metal electrode has an opening, and the current collector may be exposed from the metal electrode at the opening. In this air battery, a current collector is provided in contact with the air electrode, and since this current collector is exposed from the metal electrode at the opening of the metal electrode, the current collector can also be used as the positive electrode terminal.

[0013] [7] The air battery described in [6] may further include an insulator placed between the metal electrode and the current collector to close the opening. In this air battery, since an insulator is placed between the metal electrode and the current collector to close the opening of the metal electrode, leakage of the electrolyte from the opening can be suppressed, and the metal electrode and the current collector can be insulated.

[0014] [8] In the air cell described in any of [1] to [7], the membrane may be a hollow fiber membrane having a hollow portion. In this air cell, since the membrane is a hollow fiber membrane having a hollow portion, oxygen can be supplied to the air electrode through the hollow portion of the hollow fiber membrane.

[0015] [9] In the air battery described in [8], the hollow portion of the hollow fiber membrane may be open to the outside of the air battery from both ends of the hollow fiber membrane. In this air battery, since the hollow portion of the hollow fiber membrane is open to the outside of the air battery from both ends of the hollow fiber membrane, air can be circulated from the opening on one side of the hollow fiber membrane to the opening on the other side. This allows air to be forcibly circulated in the hollow portion of the hollow fiber membrane by supplying air to the opening on one side of the hollow fiber membrane. Alternatively, for example, the air in the hollow portion of the hollow fiber membrane can be heated by the heat generated by the air battery, allowing air to circulate naturally in the hollow portion of the hollow fiber membrane. This allows for temperature control of the air battery.

[0016]

[10] In the air battery described in any of [1] to [7], a communication space is formed in the air electrode that communicates with the outside of the air battery, and the membrane may be in contact with the air electrode in the communication space. In this air battery, a communication space is formed in the air electrode that communicates with the outside of the air battery, and the membrane is in contact with the air electrode in the communication space, so that oxygen present outside the air battery can be supplied to the air electrode through the communication space and the membrane.

[0017] According to this disclosure, it is possible to reduce the weight and size.

[0018] This is a schematic longitudinal cross-sectional view of an air battery according to an embodiment. This is a schematic transverse cross-sectional view of the air battery shown in Figure 1. This is a schematic cross-sectional view of a modified air battery. This is a schematic cross-sectional view of a modified air battery. This is a schematic cross-sectional view of a modified air battery. This is a schematic cross-sectional view of a modified air battery. This is a schematic cross-sectional view of a modified air battery. This is a schematic cross-sectional view of a modified air battery. This is a schematic cross-sectional view of a modified air battery. This is a schematic cross-sectional view of an example along the line XI-XI shown in Figure 10. This is a schematic cross-sectional view of an example along the line XI-XI shown in Figure 10. This is a schematic cross-sectional view of an example along the line XI-XI shown in Figure 10.

[0019] The air battery of this embodiment will be described in detail below with reference to the drawings. In all the drawings, the same or corresponding parts are denoted by the same reference numerals, and redundant descriptions are omitted.

[0020] Figure 1 is a schematic longitudinal cross-sectional view of an air battery according to an embodiment. Figure 2 is a schematic transverse cross-sectional view of the air battery shown in Figure 1. As shown in Figures 1 and 2, the air battery 1 comprises an air electrode 2, a metal electrode 3, a separator 4, an electrolyte 5, a hollow fiber membrane 6, and an insulator 7.

[0021] The air electrode 2 is an electrode that primarily reduces oxygen in the air. In other words, the air electrode 2 is an electrode in which the oxygen reduction reaction mainly proceeds when oxygen from the air is supplied. When the air battery 1 is used as a secondary battery, the oxygen reduction reaction proceeds at the air electrode 2 during discharge, and the oxygen evolution reaction proceeds during charging. The air electrode 2 is composed of a conductive material such as activated carbon, graphite, carbon black, or Ketjenblack, to which additives such as catalysts that promote oxidation-reduction reactions are added. Examples of catalysts that can be used include precious metals or compounds thereof such as platinum, ruthenium, and iridium; transition metals or compounds thereof such as manganese, iron, and cobalt; organometallic complexes; perovskite-type oxides; and carbon materials.

[0022] The metal electrode 3 is an electrode that primarily causes metal oxidation reactions. In other words, the metal electrode 3 is an electrode where metal oxidation reactions mainly proceed. When the air battery 1 is used as a secondary battery, metal oxidation (dissolution) reactions proceed in the metal electrode 3 during discharge, and metal reduction (deposition) reactions proceed during charging. As the metal material that forms the metal electrode 3, for example, metal species such as zinc, lithium, aluminum, iron, calcium, sodium, manganese, magnesium, nickel, lead, tin, and cadmium, or their oxides, can be used.

[0023] The separator 4 prevents direct contact between the air electrode 2 and the metal electrode 3. The separator 4 is formed, for example, as a film or plate. As the material for forming the separator 4, a porous membrane or resin nonwoven fabric made of resin materials such as cellulose, polyethylene, polyolefins such as polypropylene, polytetrafluoroethylene, polyvinylidene fluoride, etc., is used.

[0024] Electrolyte 5 is a substance that moves ions between the air electrode 2 and the metal electrode 3. As electrolyte 5, for example, aqueous solutions of sodium chloride, potassium chloride, sodium hydroxide, potassium hydroxide, etc., or non-aqueous solutions can be used.

[0025] The hollow fiber membrane 6 is a membrane that allows gases such as oxygen to permeate but does not allow liquids such as electrolytes 5 to permeate. The hollow fiber membrane 6 is a hollow fiber membrane having a hollow portion 61. The material, membrane shape, and membrane form of the hollow fiber membrane 6 are not particularly limited. Examples of materials for the hollow fiber membrane 6 include polyolefin resins such as polypropylene, polyethylene, and polymethylpentene, silicon resins such as polydimethylsiloxane and its copolymers, and fluorine resins such as PTFE and vinylidene fluoride. Examples of membrane shapes (sidewall shapes) of the hollow fiber membrane 6 include porous membranes, microporous membranes, and homogeneous membranes (non-porous membranes) that do not have porosity. Examples of membrane forms of the hollow fiber membrane 6 include symmetrical membranes (homogeneous membranes) in which the chemical or physical structure of the entire membrane is homogeneous, and asymmetrical membranes (heterogeneous membranes) in which the chemical or physical structure of the membrane differs depending on the part of the membrane. An asymmetrical membrane (heterogeneous membrane) is a membrane having a non-porous dense layer and a porous layer. Non-porous means that a material does not have pores through which liquid can permeate. Porous means that a material has pores through which liquid can permeate. In this case, the dense layer may be formed anywhere in the membrane, such as on the surface or inside the porous membrane. Heterogeneous membranes also include composite membranes with different chemical structures and multilayer membranes such as three-layer structures. Heterogeneous membranes using poly-4-methylpentene-1 resin are particularly preferred because they have a dense layer that blocks liquid. A microporous membrane is a membrane that has pores through which liquid cannot permeate. The hollow fiber membrane 6 may be a water-repellent membrane or a hydrophilic membrane. If the hollow fiber membrane 6 is a water-repellent membrane, the contact angle between the hollow fiber membrane 6 and water may be, for example, 90 degrees or more.

[0026] The insulator 7 is placed between the air electrode 2 and the metal electrode 3 to electrically insulate them. As materials for forming the insulator 7, various resins such as polypropylene (PP), polyethylene (PE), epoxy, urethane, and rubber, or non-conductive materials such as glass and ceramics can be used.

[0027] The metal electrode 3 is positioned around the air electrode 2, separator 4, electrolyte 5, and hollow fiber membrane 6, and houses the air electrode 2, separator 4, electrolyte 5, and hollow fiber membrane 6. In other words, the metal electrode 3 also functions as a case that houses the air electrode 2, separator 4, electrolyte 5, and hollow fiber membrane 6.

[0028] The metal electrode 3 is formed in a container-like (case-like) shape and has a shape corresponding to the outer shape of the air battery 1. The metal electrode 3 forms at least a part of the outer casing material of the air battery 1. The metal electrode 3 has a housing portion 31 for housing the air electrode 2, separator 4, electrolyte 5, and hollow fiber membrane 6, and an opening 32 that opens the housing portion 31 to the outside of the air battery 1. The end face of the metal electrode 3 opposite to the opening 32 is the negative electrode terminal 12 of the air battery 1.

[0029] The air electrode 2 is positioned in the housing 31 at a distance from the metal electrode 3. The air electrode 2 is exposed from the metal electrode 3 at the opening 32. The air electrode 2 has a projection 21 that protrudes from the opening 32, and this projection 21 is the positive electrode terminal 11 of the air battery 1.

[0030] The separator 4 is positioned in the region between the air electrode 2 and the metal electrode 3 of the housing 31 so as to cover the air electrode 2. The electrolyte 5 is positioned together with the separator 4 in the region between the air electrode 2 and the metal electrode 3 of the housing 31. The insulator 7 is positioned between the air electrode 2 and the metal electrode 3 and closes the opening 32.

[0031] The hollow fiber membrane 6 is positioned in the housing section 31 so as to be in contact with the air electrode 2. As a result, air supplied to the hollow portion 61 of the hollow fiber membrane 6 permeates through the membrane 6, supplying oxygen to the air electrode 2. At this time, some of the air that has permeated through the hollow fiber membrane 6 may remain in the housing section 31 without being used in the reduction reaction of the air electrode 2. Also, when the air battery 1 is used as a secondary battery, the oxygen generation reaction proceeds at the air electrode 2 during charging, generating gases such as oxygen. In these cases, gases such as oxygen will be present in the housing section 31, but these gases will permeate through the hollow fiber membrane 6 and be discharged to the outside of the housing section 31 via the hollow portion 61. This allows for the discharge of gases such as oxygen present in the housing section 31 to the outside of the housing section 31 while suppressing leakage of the electrolyte 5.

[0032] The hollow fiber membrane 6 may be a single fiber or multiple fibers. The hollow fiber membrane 6 may be arranged so as to be in contact with the outer surface of the air electrode 2, or it may be arranged so as to penetrate the air electrode 2. If there are multiple hollow fiber membranes 6, the multiple hollow fiber membranes 6 may be arranged in a ring shape or bundled together.

[0033] The hollow fiber membrane 6 is arranged to penetrate the air electrode 2 by alternately overlapping the air electrode layer (not shown) that forms part of the air electrode 2 with the hollow fiber membrane 6 (or group of hollow fiber membranes 6) from the central or outer side of the air electrode 2, thereby embedding the hollow fiber membrane 6 (or group of hollow fiber membranes 6) in the air electrode layer.

[0034] The hollow portion 61 of the hollow fiber membrane 6 may or may not be open to the outside of the air battery 1. When the hollow portion 61 of the hollow fiber membrane 6 is said to be open to the outside of the air battery 1, it means that the hollow portion 61 of the hollow fiber membrane 6 is in communication with the space outside the air battery 1. On the other hand, when the hollow portion 61 of the hollow fiber membrane 6 is said not to be open to the outside of the air battery 1, it means that the hollow portion 61 of the hollow fiber membrane 6 is not in communication with the space outside the air battery 1. In this embodiment, as an example, the hollow portion 61 of the hollow fiber membrane 6 will be described as being open to the outside of the air battery 1.

[0035] When the hollow portion 61 is open to the outside of the air battery 1, the hollow portion 61 may be open to the outside of the air battery 1 from both ends of the hollow fiber membrane 6, or it may be open to the outside of the air battery 1 from one end of the hollow fiber membrane 6. In this embodiment, as an example, the hollow portion 61 will be described as being open to the outside of the air battery 1 from one end of the hollow fiber membrane 6.

[0036] One end 62 of the hollow portion 61 is open to the outside of the air battery 1, while the other end 63 of the hollow portion 61 is not open to the outside of the air battery 1. The one end 62 of the hollow portion 61 is open to the outside of the air battery 1, for example, by the hollow fiber membrane 6 penetrating the insulator 7. The other end 63 of the hollow portion 61 is not open to the outside of the air battery 1, for example, by sealing the hollow fiber membrane 6 itself by crushing the end of the hollow fiber membrane 6 in advance, or by sealing it with the air electrode 2.

[0037] Thus, in the air battery 1 according to this embodiment, since the oxygen-permeable hollow fiber membrane 6 is in contact with the air electrode 2, oxygen from the air can be supplied to the air electrode 2 through the hollow fiber membrane 6. Furthermore, since the metal electrode 3 is arranged around the air electrode 2, separator 4, electrolyte 5, and hollow fiber membrane 6, the metal electrode 3 can function as a case that houses the air electrode 2, separator 4, electrolyte 5, and hollow fiber membrane 6. As a result, it can be used as an air battery without the need for the metal outer casing described in Patent Document 1. This allows for weight reduction and miniaturization.

[0038] Furthermore, in this air battery 1, since the metal electrode 3 houses the air electrode 2, separator 4, electrolyte 5, and hollow fiber membrane 6, it can be used as an air battery without the need for the metal casing described in Patent Document 1. This allows for weight reduction and miniaturization.

[0039] Furthermore, in this air battery 1, since the metal electrode 3 forms at least a part of the outer casing material of the air battery 1, it can be made lighter and smaller.

[0040] Furthermore, in this air battery 1, since the air electrode 2 is exposed from the metal electrode 3 at the opening 32 of the metal electrode 3, the air electrode 2 can also be used as the positive electrode terminal 11.

[0041] Furthermore, this air battery 1 includes an insulator 7 positioned between the air electrode 2 and the metal electrode 3 to close the opening 32 of the metal electrode 3. This suppresses leakage of the electrolyte 5 from the opening 32 and also provides insulation between the air electrode 2 and the metal electrode 3.

[0042] Furthermore, in this air battery 1, since the membrane is a hollow fiber membrane 6 having a hollow portion 61, oxygen can be supplied to the air electrode 2 through the hollow portion 61 of the hollow fiber membrane 6.

[0043] While preferred embodiments of this disclosure have been described above, this disclosure is not limited to the embodiments described above.

[0044] For example, in the above embodiment, the description has been made assuming that a separator is provided. However, if the air electrode and the metal electrode do not contact each other, it may be configured without a separator.

[0045] Further, for example, like the air battery 1A of the modified example shown in FIG. 3 and the air battery 1B of the modified example shown in FIG. 4, the shapes of the positive electrode and the negative electrode may be reversed.

[0046] FIG. 3 is a schematic cross-sectional view of an air battery of a modified example. The air battery 1A of the modified example shown in FIG. 3 includes an air electrode 2A, a metal electrode 3A, a separator 4, an electrolyte 5, a hollow fiber membrane 6, and an insulator 7.

[0047] The air electrode 2A is basically the same as the air electrode 2 of the above embodiment, but is different from the air electrode 2 of the above embodiment in that the protruding portion 21A corresponding to the protruding portion 21 does not protrude from the opening 32. And the end face exposed from the opening 32 of the protruding portion 21A (air electrode 2A) serves as the positive electrode terminal 11 of the air battery 1A.

[0048] The metal electrode 3A is basically the same as the metal electrode 3 of the above embodiment, but is different from the metal electrode 3 of the above embodiment in that it has a protruding portion 33 whose end face on the side opposite to the opening 32 protrudes. And this protruding portion 33 serves as the negative electrode terminal 12 of the air battery 1A.

[0049] FIG. 4 is a schematic cross-sectional view of an air battery of a modified example. The air battery 1B of the modified example shown in FIG. 4 includes an air electrode 2, a metal electrode 3B, a separator 4, an electrolyte 5, a hollow fiber membrane 6, and an insulator 7B.

[0050] The metal electrode 3B is basically the same as the metal electrode 3 of the above embodiment, but is different from the metal electrode 3 of the above embodiment in that it has a protruding portion 33 whose end face on the side opposite to the opening 32 protrudes. And this protruding portion 33 serves as the negative electrode terminal 12 of the air battery 1B. Note that the protruding portion 21 of the air electrode 2 protrudes from the opening 32 through the opening 32 and serves as the positive electrode terminal 11 of the air battery 1B, as in the above embodiment.

[0051] The insulator 7B is basically the same as the insulator 7 in the above embodiment, but differs from the insulator 7 in that, like the protruding portion 33, it protrudes from the opening 32. In this case, the protruding height of the insulator 7B relative to the opening 32 may be the same as the protruding height of the protruding portion 21 relative to the opening 32, or it may be different from the protruding height of the protruding portion 21 relative to the opening 32.

[0052] Furthermore, as shown in the modified air battery 1C in Figure 5, for example, a current collector may be provided to collect the current generated inside the air battery and transmit it to an external circuit.

[0053] Figure 5 is a schematic cross-sectional view of a modified air battery. The modified air battery 1C shown in Figure 5 comprises an air electrode 2C, a metal electrode 3, a separator 4, an electrolyte 5, a hollow fiber membrane 6, an insulator 7C, and a current collector 8.

[0054] The air electrode 2C is basically the same as the air electrode 2 in the above embodiment, but differs from the air electrode 2 in that the protruding portion 21 of the above embodiment is not formed, and a hole 22 is formed from the end face on the opening 32 side toward the opposite side of the opening 32.

[0055] The current collector 8 is for collecting the current generated inside the air battery 1C and transmitting it to an external circuit. The current collector 8 is inserted into the hole 22 of the air electrode 2C and is positioned to contact the air electrode 2C. The current collector 8 has a protrusion 81 that passes through the opening 32 and protrudes from the opening 32, and this protrusion 81 is the positive electrode terminal 11 of the air battery 1C.

[0056] The insulator 7C is basically the same as the insulator 7 in the above embodiment, but differs from the insulator 7 in that it is placed between the metal electrode 3 and the current collector 8 to close the opening 32 of the metal electrode 3.

[0057] In this way, by providing the current collector 8, the current generated inside the air battery can be efficiently collected and transmitted to the external circuit.

[0058] Furthermore, by providing an insulator 7C positioned between the metal electrode 3 and the current collector 8 to close the opening 32 of the metal electrode 3, leakage of the electrolyte 5 from the opening 32 can be suppressed, and the metal electrode 3 and the current collector 8 can be insulated.

[0059] Furthermore, as shown in the modified air battery 1D in Figure 6, for example, the metal electrodes may be covered with an outer material such as a film. The outer material may include, for example, the name of the manufacturer, the product number, the specifications of the air battery, and warnings.

[0060] Figure 6 is a schematic cross-sectional view of a modified air battery. The modified air battery 1D shown in Figure 6 comprises an air electrode 2, a metal electrode 3, a separator 4, an electrolyte 5, a hollow fiber membrane 6, an insulator 7, and an outer casing material 9.

[0061] The outer casing 9 covers at least a portion of the metal electrode 3. The outer casing 9 also functions as an outer case, protective cover, etc., for the air battery 1D. As the outer casing 9, metals such as aluminum and stainless steel, resin films and laminates such as polypropylene (PP), polyethylene (PE), polyvinyl chloride (PVC), polymethylpentene (PMP), and polyethylene terephthalate (PET), glass, ceramics, etc. can be used.

[0062] In this way, the outer casing 9 protects the air battery 1D and allows for easy display of various information such as the manufacturer's name, model number, specifications, and warnings.

[0063] Furthermore, as shown in the modified air battery 1E in Figure 7, the modified air battery 1F in Figure 8, and the modified air battery 1G in Figure 9, the hollow portion of the hollow fiber membrane may be open to the outside of the air battery from both ends of the hollow fiber membrane.

[0064] Figure 7 is a schematic cross-sectional view of a modified air battery. The modified air battery 1E shown in Figure 7 comprises an air electrode 2, a metal electrode 3, a separator 4, an electrolyte 5, a hollow fiber membrane 6E, and an insulator 7.

[0065] The hollow fiber membrane 6E is basically the same as the hollow fiber membrane 6 of the above embodiment, but differs from the hollow fiber membrane 6 of the above embodiment in that the hollow portion 61E is open to the outside of the air battery 1E from both ends of the hollow fiber membrane 6E. The hollow fiber membrane 6E extends in a U shape inside the air electrode 2 and penetrates the insulator 7 at both ends. As a result, one end 62E and the other end 63E of the hollow portion 61E are open to the outside of the air battery 1E.

[0066] Figure 8 is a schematic cross-sectional view of a modified air battery. The modified air battery 1F shown in Figure 8 comprises an air electrode 2, a metal electrode 3F, a separator 4, an electrolyte 5, a hollow fiber membrane 6F, an insulator 7, and an insulator 7F.

[0067] The metal electrode 3F is basically the same as the metal electrode 3 in the above embodiment, but differs from the metal electrode 3 in that an opening 34 is also formed on the end face opposite to the opening 32. In other words, in the metal electrode 3F, the housing portion 31 is open to the outside of the air battery 1F at the openings 32 and 34.

[0068] The insulator 7F, like the insulator 7, is placed between the air electrode 2 and the metal electrode 3F to electrically insulate the air electrode 2 and the metal electrode 3F. The insulator 7F is placed between the air electrode 2 and the metal electrode 3F and closes the opening 34. The material forming the insulator 7F can be, for example, the same as the material forming the insulator 7.

[0069] The hollow fiber membrane 6F is basically the same as the hollow fiber membrane 6 of the above embodiment, but differs from the hollow fiber membrane 6 of the above embodiment in that the hollow portion 61F is open to the outside of the air battery 1F from both ends of the hollow fiber membrane 6F. The hollow fiber membrane 6F extends in a straight line, penetrating the insulator 7 at one end and the insulator 7F at the other end. As a result, one end 62F and the other end 63F of the hollow portion 61F are open to the outside of the air battery 1F.

[0070] Figure 9 is a schematic cross-sectional view of a modified air battery. The modified air battery 1G shown in Figure 9 comprises an air electrode 2, a metal electrode 3, a separator 4, an electrolyte 5, a hollow fiber membrane 6G, and an insulator 7.

[0071] The hollow fiber membrane 6G is basically the same as the hollow fiber membrane 6 of the above embodiment, but differs from the hollow fiber membrane 6 of the above embodiment in that the hollow portion 61G is open to the outside of the air battery 1G from both ends of the hollow fiber membrane 6G. The hollow fiber membrane 6G extends in a straight line, penetrating the insulator 7 at one end and the separator 4, electrolyte 5, and metal electrode 3 at the other end. As a result, one end 62G and the other end 63G of the hollow portion 61G are open to the outside of the air battery 1G.

[0072] In this way, because the hollow portion of the hollow fiber membrane is open to the outside of the air cell from both ends, air can be circulated from one opening to the other. This allows air to be forcibly circulated in the hollow portion of the hollow fiber membrane by supplying air to one opening. Alternatively, for example, the air in the hollow portion of the hollow fiber membrane can be heated by the heat generated by the air cell, allowing air to circulate naturally. This enables temperature control of the air cell.

[0073] Furthermore, for example, if the hollow portion of the hollow fiber membrane is open to the outside of the air battery from both ends of the hollow fiber membrane, the air battery may be equipped with an air supply device that supplies air to the opening on one side of the hollow fiber membrane.

[0074] Furthermore, for example, if the hollow portion of the hollow fiber membrane is open to the outside of the air battery from both ends of the hollow fiber membrane, the hollow fiber membranes of multiple air batteries may be connected to each other.

[0075] Furthermore, although the above embodiment was described as a hollow fiber membrane having a hollow portion, the membrane may be a membrane other than a hollow fiber membrane, for example, a flat membrane without a hollow portion, as shown in Figure 10 of the air cell.

[0076] Figure 10 is a schematic cross-sectional view of a modified air battery. The modified air battery 1H shown in Figure 10 comprises an air electrode 2H, a metal electrode 3, a separator 4, an electrolyte 5, a flat membrane 6H, and an insulator 7.

[0077] The air electrode 2H is basically the same as the air electrode 2 in the above embodiment, but differs from the air electrode 2 in that it has a communication space 23H that communicates with the outside of the air battery 1H. The communication space 23H communicates with the outside of the air battery 1H, for example, by penetrating the insulator 7.

[0078] The shape, position, size, number, etc., of the communication space 23H are not particularly limited. Figures 11 to 13 are schematic cross-sectional views of an example along the line XI-XI shown in Figure 10. As shown in Figure 11, the air battery 1H may have one cylindrical communication space 23H. Also, as shown in Figure 12, the air battery 1H may have multiple (two) curved plate-shaped communication spaces 23H. Also, as shown in Figure 13, the air battery 1H may have multiple (four) flat plate-shaped communication spaces 23H.

[0079] The flat membrane 6H is basically the same as the hollow fiber membrane 6 in the above embodiment, but differs from the hollow fiber membrane 6 in that it is formed in a flat membrane shape and does not have a hollow portion. The flat membrane 6H is arranged in the communication space 23H. The flat membrane 6H is in contact with the air electrode 2H in the communication space 23H so as to cover the air electrode 2H from the communication space 23H. In the air battery 1H shown in Figure 11, the flat membrane 6H is in contact with the air electrode 2H in one cylindrical communication space 23H so as to cover the air electrode 2H from one cylindrical communication space 23H. In the air battery 1H shown in Figure 12, the flat membrane 6H is in contact with the air electrode 2H in each of the multiple (two) curved plate-shaped communication spaces 23H so as to cover the air electrode 2H from each of the multiple (two) curved plate-shaped communication spaces 23H. In the air battery 1H shown in Figure 13, the flat membrane 6H is in contact with the air electrode 2H in each of the multiple (four) flat plate-shaped communicating spaces 23H, so as to cover the air electrode 2H from each of the multiple (four) flat plate-shaped communicating spaces 23H.

[0080] Thus, a communication space 23H is formed in the air electrode 2H that communicates with the outside of the air battery 1H, and the flat film 6H is in contact with the air electrode 2H in the communication space 23H. Therefore, oxygen present outside the air battery 1H can be supplied to the air electrode 2H through the communication space 23H and the flat film 6H.

[0081] Furthermore, for example, in addition to the air electrode, metal electrode, and current collector, conductive members forming the positive and negative electrode terminals may also be provided.

[0082] 1...Air battery, 1A...Air battery, 1B...Air battery, 1C...Air battery, 1D...Air battery, 1E...Air battery, 1F...Air battery, 1G...Air battery, 1H...Air battery, 2...Air electrode, 2A...Air electrode, 2C...Air electrode, 2H...Air electrode, 3...Metal electrode, 3A...Metal electrode, 3B...Metal electrode, 3F...Metal electrode, 4...Separator, 5...Electrolyte, 6...Hollow fiber membrane (membrane), 6E...Hollow fiber membrane (membrane), 6F...Hollow fiber membrane (membrane), 6G...Hollow fiber membrane (membrane), 6H...Flat membrane (membrane), 7...Insulator 7B...insulator, 7C...insulator, 7F...insulator, 8...current collector, 9...outer material, 11...positive terminal, 12...negative terminal, 21...protrusion, 21A...protrusion, 22...hole, 23H...communication space, 31...housing section, 32...opening, 33...protrusion, 34...opening, 61...hollow section, 61E...hollow section, 61F...hollow section, 61G...hollow section, 62...tip, 62E...tip, 62F...tip, 62G...tip, 63...tip, 63E...tip, 63F...tip, 63G...tip, 81...protrusion.

Claims

1. An air cell comprising an air electrode, a metal electrode, an electrolyte, and an oxygen-permeable membrane in contact with the air electrode, wherein the metal electrode is positioned around the air electrode and the electrolyte.

2. The air battery according to claim 1, wherein the metal electrode houses the air electrode and the electrolyte.

3. The air battery according to claim 1 or 2, wherein the metal electrode forms at least a part of the outer casing material of the air battery.

4. The air battery according to claim 1 or 2, wherein the metal electrode has an opening, and the air electrode is exposed from the metal electrode at the opening.

5. The air battery according to claim 4, further comprising an insulator disposed between the air electrode and the metal electrode to close the opening.

6. The air battery according to claim 1 or 2, further comprising a current collector in contact with the air electrode, wherein the metal electrode has an opening, and the current collector is exposed from the metal electrode at the opening.

7. The air battery according to claim 6, further comprising an insulator disposed between the metal electrode and the current collector to close the opening.

8. The air battery according to claim 1 or 2, wherein the membrane is a hollow fiber membrane having a hollow portion.

9. The air battery according to claim 8, wherein the hollow portion of the hollow fiber membrane is open to the outside of the air battery from both ends of the hollow fiber membrane.

10. The air electrode has a communication space that communicates with the outside of the air battery, and the membrane is in contact with the air electrode in the communication space, according to claim 1 or 2.

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