JP2024007839A - Metal-air battery and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the occurrence of peeling at the interface of a metal-air battery.

SOLUTION: A metal-air battery 1 includes an air electrode 2 including a water-repellent film 21 in an exterior body having an opening 42, and a metal pole. A packaging material constituting the exterior body has a welded region 43 in which the water-repellent film 21 is welded to the peripheral edge of the opening 42. The welded region 43 includes a first convex portion 431 and a second convex portion 432 that bulge outward at least on the outer circumferential side and the inner circumferential side of the welding region 43. The air electrode 2 is arranged so as to overlap the first convex portion 431 on the outer peripheral side with the water-repellent film 21 in between.

SELECTED DRAWING: Figure 9B

COPYRIGHT: (C)2024,JPO&INPIT

Description

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

In recent years, various batteries using chemical reactions of electrode metals have been put into practical use, one of which is a metal-air battery. A metal-air battery is equipped with an air electrode (positive electrode), a metal electrode (negative electrode), and an electrolyte (or electrolyte solution), and through an electrochemical reaction, it can produce zinc, iron, magnesium, aluminum, sodium, calcium, or Electrical energy obtained in the process of converting metals such as lithium into metal oxides is extracted and used.

This type of metal-air battery has a laminated exterior body with an opening covered with a water-repellent film. For example, as disclosed in Patent Document 1, the exterior body has an opening covered with the water-repellent film of the air electrode, and the water-repellent film is thermally welded and integrated along the entire circumference of the opening. ing.

Japanese Patent Application Publication No. 2016-146257

In conventional metal-air batteries, when the water-repellent film and the exterior body are welded together, unevenness tends to occur in the welded area, and the resulting unevenness creates gaps at the interface between the catalyst layer and the water-repellent film of the air electrode, for example. It becomes easier. As a result, peeling is likely to occur starting from the interface where a gap has occurred, and there is still room for improvement in improving the output of metal-air batteries.

The present disclosure has been made in view of the above-mentioned problems, and its purpose is to improve the interfacial adhesion of the air electrode of a metal-air battery, suppress the occurrence of peeling, and improve battery characteristics. An object of the present invention is to provide a metal-air battery and a method for manufacturing the same that can ensure the following.

In order to achieve the above object, a metal-air battery according to the present disclosure includes an air electrode including a water-repellent film and a metal electrode in an exterior body having an opening, and the exterior body has a peripheral edge of the opening. A welded area where the water-repellent film is welded is continuously provided, and the welded area has a convexity bulging outward of the exterior body at least on the outer circumferential side and the inner circumferential side of the welded area. The air electrode is characterized in that it is arranged so as to overlap the convex portion on the outer peripheral side with the water-repellent film interposed therebetween.

Further, in the metal-air battery, it is preferable that the convex portion on the outer circumferential side of the welding region has a thickness greater than the convex portion on the inner circumferential side.

Further, in the metal-air battery, the convex portion on the outer peripheral side of the welding region may be arranged so that a portion thereof protrudes from the outer edge of the air electrode.

Further, in the metal-air battery, a plurality of the welding regions may be provided at a peripheral edge of the opening.

Further, in the metal-air battery, a plurality of the welded regions are provided adjacently, and the convex portion on the inner circumferential side of one of the adjacent welded regions and the convex portion on the outer circumferential side of the other welded region. The shaped portion may be provided integrally.

Further, in the metal air battery, the air electrode is a laminate of a current collector and a catalyst layer, and the catalyst layer is formed between the convex portion on the outer circumferential side and the convex portion on the inner circumferential side. A convex portion corresponding to the concave portion may be provided.

Further, in the metal air battery, the air electrode is a laminate of a current collector and a catalyst layer, the current collector is a porous material, and the water-repellent film is on the side of the catalyst layer of the current collector. may be provided.

Furthermore, a method for manufacturing a metal-air battery having the above-mentioned configuration is also within the scope of the technical idea of the present disclosure. That is, a method for manufacturing a metal-air battery that includes a water-repellent film, an air electrode, and a metal electrode in an exterior body having an opening, the method comprising: welding the water-repellent membrane to the peripheral edge of the opening of the exterior body; a welding area is provided, and a convex portion that bulges outward of the exterior body is provided at least on the outer circumferential side and the inner circumferential side of the welding area, and the air electrode is connected to the air electrode through the water-repellent film, It is characterized in that it is arranged so as to overlap the convex portion on the outer peripheral side.

According to the present disclosure, it is possible to increase the interfacial adhesion in the air electrode of a metal-air battery and suppress the occurrence of peeling.

FIG. 1 is a front view showing a metal-air battery according to an embodiment of the present disclosure. FIG. 2 is a perspective view showing a stacked structure of the metal-air battery. FIG. 3 is a cross-sectional view showing a water-repellent film provided on the metal-air battery. FIG. 3 is a cross-sectional view showing a packaging material that constitutes the exterior body of the metal-air battery. FIG. 3 is an explanatory plan view showing a welded area with the water-repellent film in the packaging material. FIG. 2 is a cross-sectional explanatory diagram schematically showing a welding process of the metal-air battery according to Embodiment 1. FIG. 3 is an explanatory cross-sectional view schematically showing a convex portion provided on the packaging material by the welding process. It is an explanatory view showing an example of a welding horn used in the welding process. FIG. 3 is a cross-sectional explanatory diagram schematically showing a lamination process of the packaging material and the air electrode. FIG. 2 is a cross-sectional explanatory view schematically showing the packaging material and the air electrode that have undergone the lamination process. FIG. 2 is a cross-sectional explanatory diagram schematically showing a welding region in a metal-air battery according to a second embodiment. It is an explanatory view showing an example of a welding horn used in the welding process of the metal-air battery. It is an explanatory view showing other examples of a welding horn used in the welding process. FIG. 3 is a cross-sectional explanatory diagram schematically showing a lamination process of the packaging material and the air electrode. FIG. 2 is a cross-sectional explanatory view schematically showing the packaging material and the air electrode that have undergone the lamination process. FIG. 7 is a cross-sectional explanatory diagram schematically showing a lamination process in a metal-air battery according to Embodiment 3. FIG. 2 is a cross-sectional explanatory view schematically showing the packaging material and the air electrode that have undergone the lamination process. FIG. 7 is a cross-sectional explanatory diagram schematically showing a lamination process in a modified example of the metal-air battery according to Embodiment 3. FIG. 2 is a cross-sectional explanatory view schematically showing the packaging material and the air electrode that have undergone the lamination process. FIG. 7 is an explanatory cross-sectional view schematically showing the packaging material and the air electrode in a metal-air battery according to Embodiment 4. It is an explanatory view showing an example of a welding horn used in the welding process of the metal-air battery. FIG. 7 is a cross-sectional explanatory diagram schematically showing the packaging material and the air electrode in a metal-air battery according to Embodiment 5. It is a characteristic chart showing the results of characteristic evaluation of the metal-air battery. FIG. 3 is an explanatory diagram showing the structure of a sealing region in characteristic evaluation of the metal-air battery. FIG. 2 is a cross-sectional explanatory diagram schematically showing a stacking process of a conventional metal-air battery. FIG. 2 is a cross-sectional explanatory diagram schematically showing a packaging material and an air electrode in a conventional metal-air battery.

A metal-air battery 1 and a manufacturing method thereof according to an embodiment of the present disclosure will be described with reference to the drawings.

1 and 2 show a metal air battery 1 according to an embodiment of the present disclosure, FIG. 1 is a front view of the metal air battery 1, and FIG. 2 is a perspective view showing the laminated structure inside the exterior body 4 of the metal air battery 1. It is a diagram.

The metal-air battery 1 according to this embodiment is a battery in which the metal electrode 3 is a negative electrode (anode) and the air electrode 2 is a positive electrode (cathode). Examples of the metal-air battery 1 include a zinc-air battery, a lithium-air battery, a sodium-air battery, a calcium-air battery, a magnesium-air battery, an aluminum-air battery, and an iron-air battery.

The metal-air battery 1 has an electrolytic solution (not shown) inside an exterior body 4 as a battery case, and has two positive electrodes (air and air), a first air electrode 201 and a second air electrode 202. electrode 2) and one negative electrode (metal electrode 3) in an electrolytic solution. The metal electrode 3 is provided between the first air electrode 201 and the second air electrode 202, and contains a metal serving as an electrode active material. Note that the positive electrode may be configured to include one air electrode 2 and one charging electrode.

In the metal-air battery 1, the exterior body 4, which is a battery case, is provided with an opening 42 that penetrates the outer surface and the inner surface. As shown in FIG. 2, the air electrode 2 is disposed inside the exterior body 4, adjacent to the opening 42, and is provided so as to cover the opening 42. The openings 42 are provided in each packaging material 41 that is a member of the exterior body 4 .

The metal electrode 3 is an electrode containing an active material (negative electrode active material), is held in the exterior body 4 so as to be in contact with the electrolytic solution, and is placed between the two air electrodes 2 . As the active material, metal elements such as zinc, lithium, sodium, calcium, magnesium, aluminum, and iron are used. The metal electrode 3 has a negative electrode lead portion 32 extending from a negative electrode current collector 31, so that the metal electrode 3 can be electrically connected to an external circuit.

The electrolytic solution is a liquid having ionic conductivity, and includes an electrolyte dissolved in a solvent. Although the type of electrolytic solution varies depending on the type of negative electrode active material contained in the metal electrode 3, it is preferably an electrolytic solution using an aqueous solvent (aqueous electrolyte solution).

When a zinc-air battery, an aluminum-air battery, an iron-air battery, or the like is applied as the metal-air battery 1, an alkaline aqueous solution such as a sodium hydroxide aqueous solution or a potassium hydroxide aqueous solution can be used as the electrolyte. In the case of a magnesium air battery, a sodium chloride aqueous solution can be used as the electrolyte. Furthermore, in the case of a lithium-air battery, an organic electrolyte can be used. The electrolytic solution may contain organic additives or inorganic additives other than the electrolyte, or may be gelled with polymeric additives.

In the case of a zinc-air battery as an example of the metal-air battery 1, zinc can be used as the active material of the metal electrode 3, and a potassium hydroxide aqueous solution can be used as the electrolyte. Note that the metal electrode 3 is not limited to these configurations, and other materials may be used, and the electrolyte may be appropriately selected depending on the combination with the metal electrode 3.

As shown in FIG. 2, the air electrode 2 includes a water-repellent film 21, a current collector 22, and a catalyst layer 24 laminated in this order inside an exterior body 4. The water-repellent film 21 is provided so as to face the opening 42 of the exterior body 4. Since the opening 42 is covered by the water-repellent film 21 of the air electrode 2, the electrolyte does not flow out from the opening 42, and only air can pass through. Further, the water-repellent film 21 is formed of a porous material containing a water-repellent resin, and is disposed on one side of the current collector 22 between the exterior body 4 and the current collector 22. Ru.

The current collector 22 constituting the air electrode 2 is porous and has electron conductivity, and is formed into a mesh shape (network structure) using, for example, a metal wire material, and is a porous material having a large number of through holes. It is considered to be a material. The material of the metal wire used for the current collector 22 is not limited and any known material can be used, but for example, one or more types can be selected from stainless steel, nickel, copper, aluminum, tungsten, titanium, etc. . The air electrode 2 has an air electrode lead portion 23 extending from a current collector 22, so that the air electrode 2 can be electrically connected to an external circuit. The air electrode lead portion 23 is made of foil such as metal foil, for example.

The current collector 22 is not limited to a mesh shape, and may be a porous material such as an expanded metal, a punched metal, an etched material, a sintered body of metal particles or metal fibers, or a foamed metal. However, in consideration of a suitable anchoring effect for the water-repellent film 21, it is more preferable that the current collector 22 has a mesh shape.

Further, as shown in FIG. 2, the catalyst layer 24 is disposed facing the metal electrode 3 and is in contact with the electrolyte. The catalyst layer 24 preferably includes, for example, a conductive porous carrier and a catalyst supported on the porous carrier. This makes it possible to form a three-phase interface where oxygen gas, water, and electrons coexist on the catalyst.

Examples of the catalyst contained in the catalyst layer 24 include perovskite-type oxides containing platinum group metals such as nickel, palladium and platinum, transition metals such as cobalt, manganese and iron, noble metal oxides such as ruthenium and palladium, manganese oxide, etc. can be mentioned. The conductive porous carrier is preferably a carbon material such as carbon black. The catalyst particle diameter is 100 nm to 1 μm, more preferably 100 nm to 500 nm. The thickness of the catalyst layer 24 is 100 μm to 2 mm, more preferably 500 μm to 1 mm.

In the process of producing the air electrode 2 in the metal air battery 1, the water-repellent film 21 is superimposed and welded on the packaging material 41 of the exterior body 4, and the current collector 22 and the catalyst layer 24 are then sequentially attached to the water-repellent film 21. Stack them and press them to make them stick together. The water-repellent film 21 is placed over the opening 42 provided in the packaging material 41, and the outer periphery of the opening 42 is welded. As a result, a welded region (43) in which the water-repellent film 21 is welded is continuously provided at the peripheral edge of the opening 42. Details of the welding area will be described later.

FIG. 3 is a cross-sectional view showing the water-repellent film 21 of the metal-air battery 1 according to the present embodiment, and FIG. 4 is a cross-sectional view showing the packaging material 41 constituting the exterior body 4.

As shown in FIG. 3, the water-repellent film 21 includes a backing layer 211 made of non-woven fabric and a water-repellent layer 212 made of a water-repellent resin sheet made of PTFE (polytetrafluoroethylene), which are laminated together by thermal lamination. It is considered to be a sheet material.

The backing layer 211 is welded to a heat-fusible film layer 412 of the packaging material 41, which will be described later. Since the material constituting the heat-fusible film layer 412 of the packaging material 41 is preferably PE (polyethylene), the backing layer 211 is made of a material that has a high thermal affinity with PE (having a melting point around 130 to 140°C). It is preferable that Furthermore, it is preferable that the backing layer 211 has high air permeability so as not to impede the air permeability of the water-repellent film 21. Therefore, the backing layer 211 is preferably a PE nonwoven fabric or a mixed material of PE and other resin. The thickness of the backing layer 211 is preferably 50 to 100 μm, and the air permeability is preferably 10 s/100 cc·Air or less.

The water-repellent layer 212 of the water-repellent film 21 preferably has a thickness of, for example, 100 to 250 μm, more preferably 200 to 250 μm. The water-repellent film 21 preferably has a porosity of 20 to 50%, more preferably 30 to 40%. Further, the air permeability of the water-repellent film 21 is preferably 1000 s/100 cc·Air or less. By setting the water-repellent film 21 to an appropriate thickness, durability can be ensured and adhesion with the catalyst layer 24 can be improved.

On the other hand, the packaging material 41 constituting the exterior body 4 is preferably made of a material that is corrosion resistant to the electrolytic solution, and also has heat resistance and thermal weldability. The packaging material 41 is not limited to a single-layer structure, but preferably has a multi-layer structure in which, for example, a base material layer 411 and a heat-fusible film layer 412 are laminated and integrated, as shown in FIG.

In this case, the base material layer 411 preferably contains a heat-resistant synthetic resin material, and can have the effect of preventing unnecessary deformation or breakage during sealing by heat fusion. . Therefore, for example, nylon, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), or the like can be suitably used for the base material layer 411, and nylon is particularly preferable.

The material constituting the heat-fusible film layer 412 is preferably PE (polyethylene), and other materials include polyvinyl chloride (PVC), polyvinyl acetate, ABS resin, vinylidene chloride, polyacetal, polypropylene, polyisobutylene, and fluororesin. , epoxy resin, etc. may be used.

When the packaging material 41 of the exterior body 4 has a multilayer structure including a base material layer 411 and a heat-fusible film layer 412, the base material layer 411 is disposed on the outer surface side of the exterior body 4, and Preferably, a heat-fusible film layer 412 is provided on the inner surface. This ensures the welding performance of the inner surface of the exterior body 4, increases the physical strength of the exterior body 4, and makes it possible to maintain its shape.

FIG. 5 is an explanatory plan view showing a welding region 43 between the packaging material 41 and the water-repellent film 21. In addition, in FIG. 5, the packaging material 41 is shown as seen from the outside surface side, and the region where the water-repellent film 21 layered on the inside surface side of the packaging material 41 is present is hatched, and the welded region 43 is shown in light ink color. It is shown with .

As shown in FIG. 5, the opening 42 provided in the exterior body 4 is covered with the water-repellent film 21 from the inner side, and the peripheral edge of the opening 42 is welded to the packaging material 41 (welding step). In this case, the backing layer 211 of the water-repellent film 21 is placed in contact with the heat-fusible film layer 412 of the packaging material 41 constituting the exterior body 4, and the heat-fusible film layer 412 and the backing layer 211 and are welded together. As a result, a substantially rectangular welded region 43 in which the water-repellent film 21 is welded is provided in the packaging material 41 along the peripheral edge of the opening 42 .

Note that the shape of the welding area 43 is not limited to that shown in FIG. A configuration may be adopted in which a plurality of welded regions are formed parallel to the left and right width directions, and a substantially cross-shaped welded region surrounding the opening 42 is provided.

(Embodiment 1)
FIG. 6 is a cross-sectional explanatory view schematically showing a welding process between the packaging material 41 and the water-repellent film 21, and FIG. 7 schematically shows a convex portion formed on the packaging material 41 by the welding process. It is a cross-sectional explanatory view. Although the water-repellent film 21 and the packaging material 41 have a multilayer structure as described above, in order to make the drawings easier to read, they are shown as an integrated structure without distinguishing between the layers.

In the metal-air battery 1 according to the present disclosure, the configuration of the welded region 43 between the exterior body 4 and the water-repellent film 21 can be implemented in various forms. In the following embodiments, five of them will be described.

As shown in FIG. 6, in the step of welding the packaging material 41 and the water-repellent film 21, the water-repellent film 21 is placed below, and the packaging material 41 is placed on top of it. The water-repellent film 21 is arranged at the peripheral edge so as to cover up to the outer peripheral side of the opening 42 provided in the packaging material 41. The water-repellent film 21 and packaging material 41 arranged in an overlapping manner are heat-pressed from the outer surface 41a side of the packaging material 41 in the direction of arrow P. The outer surface 41a of the packaging material 41 is a surface disposed on the outside (outer surface side) of the exterior body 4.

When the heat-fusible film layer (412) of the packaging material 41 is made of PE and the backing layer (211) of the water-repellent film 21 is made of polyolefin nonwoven fabric, the base material layer (411), which is made of, for example, nylon, does not melt. It is preferable to bond for several seconds at a temperature of about 160° C., which is the temperature at which the heat-fusible film layer (412) melts. As a result, a welded region 43 in which the water-repellent film 21 is integrated is provided at the periphery of the opening 42 of the packaging material 41.

A plurality of convex portions are formed in the welding region 43 . For example, as shown in FIG. 7, the packaging material 41 that has undergone the welding process has convex portions (first convex portions 431 and second convex portion 432) are continuously formed. A recess 434 is formed between the first convex portion 431 provided on the outer circumferential side of the opening 42 and the second convex portion 432 provided on the inner circumferential side with respect to the opening 42 . Therefore, in the welding region 43 of the packaging material 41 with the water-repellent film 21, a first convex portion 431, a concave portion 434, and a second convex portion 432 are provided in order from the outer circumferential side.

The first convex portion 431 on the outer circumferential side of the welding region 43 and the second convex portion 432 on the inner circumferential side are both bulged outward so as to have substantially the same thickness. Further, the first convex portion 431 and the second convex portion 432 are provided on the inner peripheral side of the outer edge portion 213 of the water-repellent film 21 . In particular, the first convex portion 431 is provided so as to overlap the outer edge portion 213 of the water-repellent film 21 , and in this case, the first convex portion 431 is arranged so as to be located on the inner peripheral side of the outer edge portion 213 of the water-repellent film 21 . ing.

FIG. 8 is an explanatory diagram showing an example of a process of welding the packaging material 41 and the water-repellent film 21. Welding of the packaging material 41 and the water-repellent film 21 can be performed using, for example, a welding horn 50 shown in FIG. 8. The attachment portion provided at the lower end of the welding horn 50 has a smooth surface, and is provided with a flat surface that can be pressed horizontally against the welded part.

The welding horn 50 is pressed against the outer surface 41 a of the packaging material 41 on the water-repellent film 21 at a high temperature at the peripheral edge of the opening 42 . Since the welding horn 50 has a uniform temperature as a whole, heat is transmitted equally between the outer circumference side portion P1 and the inner circumference side portion P2 shown in FIG. As a result, the packaging material 41 and the water-repellent film 21 are welded together. As shown in FIG. 5, a welded region 43 is continuously formed in the packaging material 41 so as to surround the opening 42. As shown in FIG. Furthermore, as shown in FIG. 7, the welding region 43 is provided with a first convex portion 431, a concave portion 434, and a second convex portion 432.

FIG. 9A is a cross-sectional explanatory diagram schematically showing the lamination process of the packaging material 41 and the air electrode 2, and FIG. 9B is a cross-sectional explanatory diagram schematically showing the packaging material 41 and the air electrode 2 after the lamination process. be.

The air electrode 2 is provided by laminating the current collector 22 and the catalyst layer 24 on a welded region 43 provided on the packaging material 41 via the water-repellent film 21 (lamination step). The current collector 22 and the catalyst layer 24 are laminated so as to overlap the first convex portion 431 and the second convex portion 432 of the packaging material 41, and are press-bonded.

More specifically, as shown in FIG. 9A, the packaging material 41 has a first convex portion 431 and a second convex portion 432 protruding from the outer surface 41a. The first convex portion 431 and the second convex portion 432 of the packaging material 41 are arranged facing outward (downward in the figure), and on the water-repellent film 21 welded to the inner surface 41b of the packaging material 41, The current collector 22 and the catalyst layer 24 are stacked in this order. In this case, the water-repellent film 21 is placed at a position where it completely overlaps the first convex portion 431 from the inner surface 41b side of the packaging material 41. The water-repellent film 21 is located directly above any portion of the first convex portion 431, and the water-repellent film 21 is placed inside the outer edge 213 of the water-repellent film 21. With respect to the water-repellent film 21 arranged in this manner, a current collector 22 and a catalyst layer 24 are further arranged to overlap in the same manner.

Next, the packaging material 41 having the welded region 43 with the water-repellent film 21, the water-repellent film 21, the current collector 22, and the catalyst layer 24 are stacked in this order and pressed from above and below at room temperature. As a result, as shown in FIG. 9B, an air electrode 2 in which the water-repellent film 21, the current collector 22, and the catalyst layer 24 are integrated is obtained. It is preferable that the press pressure in such a lamination step is, for example, 2.04 kN/cm ² and the press time is 2 minutes.

The first convex portion 431 and the second convex portion 432 that had protruded toward the outer surface 41a of the packaging material 41 will also protrude toward the inner surface 41b of the packaging material 41 by being pressed at room temperature in the lamination process. Become. On the inner surface 41b of the packaging material 41, a first inner surface convex portion 435 corresponding to the first convex portion 431 and a second inner surface convex portion 436 corresponding to the second convex portion 432 protrude toward the water-repellent film 21 side. . The protruding first inner surface convex portion 435 and second inner surface convex portion 436 press the water-repellent film 21 . The water-repellent film 21 is pressed by the first inner surface convex portion 435 and the second inner surface convex portion 436, whereby the protruding first anchor convex portion 214 and second anchor convex portion 215 bite into the current collector 22, and further will bite into the catalyst layer 24.

The air electrode 2 has a packaging material 41 and a water-repellent film 21 integrated through a welding region 43, and further includes a water-repellent film 21, a current collector 22, and a catalyst arranged so as to overlap with the welding region 43. The layer 24 is bonded with high strength by the biting of the first anchor protrusion 214 and the second anchor protrusion 215 of the water-repellent film 21. As a result, the interfaces between the members of the air electrode 2 are brought into close contact with each other without any gaps, making it possible to reduce the infiltration of the electrolyte and the occurrence of peeling at each interface.

The metal-air battery 1 can be obtained by using the packaging material 41 as the exterior body 4 and arranging an electrolytic solution (for example, a KOH aqueous solution), the air electrode 2, and the metal electrode 3 in the exterior body 4. In the metal-air battery 1, an electrolyte permeates into the catalyst layer 24 from the metal electrode 3 side, and air containing oxygen gas is supplied to the catalyst layer 24 from the water-repellent film 21 side of the air electrode 2. As a result, the electrode reaction (oxygen reduction reaction) progresses in the catalyst layer 24 of the air electrode 2, so that the metal-air battery 1 outputs an output.

FIGS. 21A and 21B are cross-sectional explanatory views schematically showing a step of laminating an air electrode 20 in a metal-air battery having a conventional configuration. As described above, in the conventional air electrode 20, a thin portion is formed in the packaging material 410 due to welding of the water-repellent film 210 and the packaging material 410, and as a result, the interface between the water-repellent film 210 and the current collector 220 is There are also problems in that a gap is likely to be formed at the interface between the current collector 220 and the catalyst layer 240. As shown in FIG. 21A, conventionally, among the convex portions 430 formed in the welding region between the water-repellent film 210 and the packaging material 410, the convex portions 430 on the outer circumferential side in particular do not overlap with the water-repellent film 210. Sometimes I didn't have one.

Therefore, even if the packaging material 410, the water-repellent film 210, the current collector 220, and the catalyst layer 240 are stacked in this order and pressed at room temperature from both the upper and lower sides, the convex shape on the outer periphery side remains as shown in FIG. 21B. The portion 430 protrudes from the outer circumferential side of the air electrode 20. Although the water-repellent film 210, the current collector 220, and the catalyst layer 240 are compressed by the convex portions 430 on the inner peripheral side of the packaging material 410, there is a concave portion between the two convex portions 430. , the crimping action will not work sufficiently on the outer circumferential side. As a result, the water-repellent film 210 is less likely to bite into the current collector 220 and the catalyst layer 240, making it easier to create a gap on the outer circumferential side. Due to the existence of such a gap, a portion that does not come into contact with the water-repellent film 210 is formed, and when the internal volume changes due to charging and discharging, the water-repellent film 210 and the current collector 220 or the catalyst layer 240 start from the gap. There was a risk that peeling would occur at the interface between the battery and the battery, resulting in a decrease in battery output and shortened battery life.

On the other hand, in the metal-air battery 1 according to the present embodiment, as shown in FIG. 9B, the water-repellent film 21 is disposed facing the current collector 22 made of a porous material, and the first anchor convex portion 214 and the second anchor protrusion 215 bite into the current collector 22, improving adhesiveness. Furthermore, the adhesion between the current collector 22 and the catalyst layer 24, and between the water-repellent film 21 and the catalyst layer 24 via the current collector 22, is also improved. Therefore, the water-repellent film 21, the current collector 22, and the catalyst layer 24 can be bonded and integrated with high strength.

In addition, since the water-repellent film 21 is bonded with high strength, it is possible to suppress the generation of gaps on the outer circumferential side of the air electrode 2, thereby increasing water repellency. Thereby, the air electrode 2 becomes one in which intrusion of the electrolytic solution into the space between the water-repellent film 21 and the catalyst layer 24 and separation between these members are effectively suppressed.

In the metal-air battery 1, the water-repellent film 21 is not limited to being arranged at a position completely overlapping the first convex portion 431 from the inner surface 41b side of the packaging material 41, but at least on the outer peripheral side. It suffices if they are arranged so as to overlap with the first convex portion 431.

(Embodiment 2)
FIG. 10 is an explanatory cross-sectional view schematically showing a welding region 43 between the packaging material 41 and the water-repellent film 21 in the metal-air battery 1 according to the second embodiment. FIG. 11 is an explanatory diagram schematically showing a welding process between the packaging material 41 and the water-repellent film 21, and FIG. 12 is an explanatory diagram schematically showing another example of the welding process. In the following description of each embodiment, the configuration of the welding region 43 has its own characteristics, and other configurations that are common to Embodiment 1 will be indicated by common reference numerals and redundant description will be omitted. do.

In the form shown in FIG. 10, the welding region 43 is provided with a first convex portion 431 and a second convex portion 432 with different thicknesses. In this case, of the first convex portion 431 and the second convex portion 432 of the welding region 43, the first convex portion 431 on the outer peripheral side is thicker than the second convex portion 432 on the inner peripheral side. It is set in. The first convex portion 431 projects more toward the outer surface 41a of the packaging material 41 than the second convex portion 432. Further, the width of the first convex portion 431 (the size in the direction from the inner circumferential side to the inner circumferential side) is also set larger than the width of the second convex portion 432.

Such a welding region 43 can be formed using a welding horn 50 shown in FIG. 11, for example. The welding horn 50 has a smooth inclined surface 51 that slopes downward from the inner circumferential side to the outer circumferential side at the attachment portion at the lower end. The welding horn 50 is pressed against the periphery of the opening 42 of the packaging material 41 on the water-repellent film 21 at a uniform high temperature. The outer circumference side part P1 of the packaging material 41 transmits heat better than the inner circumference side part P2, and more of the heat-fusible film layer (412) melts in the outer circumference side part P1.

As a result, the packaging material 41 and the water-repellent film 21 are welded together, and a welded region 43 is formed in the packaging material 41. As shown in FIG. 10, the welding region 43 is provided with a first convex portion 431 that is thicker than the second convex portion 432, a recess 434, and a second convex portion 432.

The welding region 43 can also be formed using a welding horn 50 shown in FIG. 12. In this case, the welding horn 50 is provided with a heat source and a heat shield having different temperatures at the attachment portion at the lower end, so that the heating temperature is sloped. For example, as shown in FIG. 12, the welding horn 50 is provided with a heat source 52 on the inner circumferential side, which has a lower temperature than the outer circumferential side, and with a heat shield 54 in between, the outer circumferential side has a lower temperature than the inner circumferential side. A high heat source 53 is provided. As a result, the outer circumference side part P1 of the packaging material 41 becomes hotter than the inner circumference side part P2, and more of the heat-fusible film layer (412) melts in the outer circumference side part P1, and the first convex part on the outer circumference side 431 is provided thicker than the second convex portion 432 on the inner peripheral side.

FIG. 13A is a cross-sectional explanatory diagram schematically showing the lamination process of the packaging material 41 and the air electrode 2, and FIG. 13B is a cross-sectional explanatory diagram schematically showing the packaging material 41 and the air electrode 2 that have undergone the lamination process. be.

The air electrode 2 is laminated and pressure-bonded to the welding region 43 provided on the packaging material 41 via the water-repellent film 21 so that the first convex portion 431 of the packaging material 41 has an overlapping portion. (Lamination process). In this embodiment, as shown in FIG. 13A, the first convex portion 431 and the second convex portion 432 of the packaging material 41 are arranged facing outward (downward in the figure) and collected on the water-repellent film 21. The electric body 22 and the catalyst layer 24 are stacked in this order. Even in this form, the water-repellent film 21 is located directly above any portion of the first convex portion 431 of the packaging material 41, and the water-repellent film 21 and the first convex portion 431 are They are placed in a completely overlapping position.

Next, as shown in FIG. 13B, the packaging material 41, the water-repellent film 21, the current collector 22, and the catalyst layer 24 are pressed at room temperature from both the upper and lower sides. As a result, an air electrode 2 in which the water-repellent film 21, the current collector 22, and the catalyst layer 24 are integrated is obtained. The first convex portion 431, which has a thickness that bulged toward the outer surface 41a of the packaging material 41, largely protrudes toward the inner surface 41b of the packaging material 41 by room-temperature pressing. A first inner surface convex portion 435 corresponding to the first convex portion 431 protrudes toward the water-repellent film 21 side to a greater extent than a second inner surface convex portion 436 corresponding to the second convex portion 432 . The first anchor protrusion 214 bites deeper into the water-repellent film 21 than the second anchor protrusion 215, and the water-repellent film 21 is pressed by these and bites into the current collector 22, and further into the catalyst layer 24.

As a result, in the air electrode 2, the packaging material 41 and the water-repellent film 21 are integrated via the welding region 43, and the first convex portion 431 on the outer peripheral side has a thickness, so that the water-repellent film 21 , the current collector 22 and the catalyst layer 24 can be further improved in adhesiveness on the outer peripheral side. As a result, it is possible to more effectively suppress the infiltration of the electrolytic solution between the members in the air electrode 2 and the occurrence of peeling of the water-repellent film 21, the current collector 22, and the catalyst layer 24.

(Embodiment 3)
FIG. 14A is a cross-sectional explanatory view schematically showing the lamination process in the metal-air battery 1 according to Embodiment 3, and FIG. 14B is a cross-sectional view schematically showing the packaging material 41 and the air electrode 2 that have undergone the lamination process. It is a diagram.

In the metal-air battery 1 according to the present disclosure, the first convex portion 431 on the outer peripheral side may be arranged so that a portion thereof protrudes from the outer edge of the air electrode 2.

In the form shown in FIG. 14A, the welding region 43 is provided with a first convex portion 431 and a second convex portion 432 having substantially the same thickness. In addition, the water-repellent film 21 is located directly above any portion of the first convex portion 431 of the welding region 43, so that the water-repellent film 21 and the first convex portion 431 completely overlap each other. It is located.

Here, in the lamination process, the current collector 22 and the catalyst layer 24 are stacked so that the first convex portion 431 of the welding region 43 partially protrudes from the outer edge of the current collector 22 and the catalyst layer 24 that constitute the air electrode 2. A layer 24 is disposed. The current collector 22 and the catalyst layer 24 are arranged so that the outer edge of the water-repellent film 21 also protrudes beyond the current collector 22 (and the catalyst layer 24).

By pressing the packaging material 41, the water-repellent film 21, the current collector 22, and the catalyst layer 24 arranged in this way at room temperature, the water-repellent film 21, the current collector 22, and the catalyst layer 24 are pressed as shown in FIG. 14B. An air electrode 2 with an integrated layer 24 is obtained. The first convex portion 431 bulging toward the outer surface 41a of the packaging material 41 protrudes toward the inner surface 41b of the packaging material 41, partially covers the outer edge of the water-repellent film 21, and bites into the water-repellent film 21. Further, in the water-repellent film 21 , the first anchor protrusion 214 and the second anchor protrusion 215 bite into the current collector 22 and the catalyst layer 24 . The first anchor convex portion 214 on the outer peripheral side further covers the outer edge portion of the catalyst layer 24 .

As a result, each interface of the air electrode 2 is bonded with high strength through the welding region 43, and furthermore, it is possible to suppress the intrusion of electrolyte from the outer peripheral side at the interface between the water-repellent film 21 and the catalyst layer 24. Become. Therefore, it becomes possible to more effectively suppress the infiltration of the electrolytic solution between the members in the air electrode 2 and the occurrence of peeling of the water-repellent film 21, the current collector 22, and the catalyst layer 24.

15A and 15B show a modified example of the metal-air battery 1 according to Embodiment 3, FIG. 15A is a cross-sectional explanatory diagram schematically showing the stacking process of the metal-air battery 1, and FIG. 15B is a stacking process FIG. 2 is a cross-sectional explanatory diagram schematically showing the packaging material 41 and the air electrode 2 after passing through the packaging material 41 and the air electrode 2. FIG.

As shown in the figure, in the metal-air battery 1, the first convex portion 431 of the welding region 43 is preferably arranged so as to overlap the water-repellent film 21 directly above it. and the first convex portion 431 do not need to completely overlap. In the example shown in FIG. 15A, the first convex portion 431 of the welding region 43 is arranged so as to overlap the water-repellent film 21, current collector 22, and catalyst layer 24 that constitute the air electrode 2 in the lamination process. The first convex portion 431 is arranged so as to partially protrude from the outer edge of the water-repellent film 21 as well.

Even if the packaging material 41, the water-repellent film 21, the current collector 22, and the catalyst layer 24 are arranged in this way, by being pressed at room temperature, the first convexity of the packaging material 41 is formed as shown in FIG. 15B. The shaped portion 431 may cover the outer edge of the water-repellent film 21 and further cover the outer edge of the current collector 22 (and the catalyst layer 24), and the water-repellent film 21, the current collector 22, and the catalyst layer It is possible to obtain an air electrode 2 in which 24 is integrated.

In this case as well, each interface of the air electrode 2 is bonded with high strength via the welding region 43, thereby suppressing the intrusion of electrolyte from the outer peripheral side at the interface between the water-repellent film 21 and the catalyst layer 24. Can be done.

(Embodiment 4)
FIG. 16 is a cross-sectional explanatory diagram schematically showing the packaging material 41 and the air electrode 2 that have undergone the lamination process in the metal-air battery 1 according to Embodiment 4, and FIG. It is an explanatory view showing typically a welding process of.

The welding region 43 having the above-mentioned structure may be arranged in a plurality of strips parallel to each other at the peripheral edge of the opening 42 of the packaging material 41. For example, the welding area 43 may be provided at the periphery of the opening 42 so as to have a substantially rectangular double inner and outer rectangular shape. Further, by providing the welding regions 43 in parallel and adjacent to each other, for example, the second convex portion of one adjacent region and the first convex portion of the other region are integrated, and one convex portion of the other region is integrated. It may be configured to form three convex portions 433. As a result, in the welding region 43 between the packaging material 41 and the water-repellent film 21, from the outer circumferential side, the first convex portion 431, the concave portion 434, the third convex portion 433, the concave portion 434, and the second convex portion 432. are provided in order.

In the lamination step, the current collector 22 and the catalyst layer 24 are laminated on the welded packaging material 41 and water-repellent film 21, and the air electrode 2 is obtained by pressing at room temperature. On the inner surface 41b side of the packaging material 41, a first inner surface convex portion 435 corresponds to the first convex portion 431, a second inner surface convex portion 436 corresponds to the second convex portion 432, and a third convex portion Third inner surface convex portions 437 protrude corresponding to the portions 433, respectively. Further, in the water-repellent film 21 , the first anchor protrusion 214 , the second anchor protrusion 215 , and the third anchor protrusion 216 bite into the current collector 22 and the catalyst layer 24 . Thereby, each interface between the water-repellent film 21, the current collector 22, and the catalyst layer 24 is bonded with high strength. In addition, since the welding region 43 has a plurality of convex portions including a first convex portion 431, a second convex portion 432, and a third convex portion 433, it is possible to prevent the infiltration of the electrolyte and the formation of each interface. The occurrence of peeling can be more effectively suppressed.

In the welding process, as shown in FIG. 17, two welding horns 50 are used together to form a welded area having a plurality of convex portions. In this case, each welding horn 50 may be similar to that shown in the previous embodiment. Note that the shape of the welding area 43 is not limited to that shown in FIG. The welding area 43 may be the same as the welding area 43 .

(Embodiment 5)
FIG. 18 is a cross-sectional explanatory diagram schematically showing the configuration of the air electrode 2 in the metal-air battery 1 according to the fifth embodiment.

The catalyst layer 24 may be provided with a convex portion 241 so as to correspond to a concave portion between the first convex portion 431 on the outer circumferential side and the second convex portion 432 on the inner circumferential side. In the illustrated form, the catalyst layer 24 is provided with a continuous convex portion 241 at the outer edge. In the lamination step, the current collector 22 and the catalyst layer 24 are laminated on the welded packaging material 41 and the water-repellent film 21, so that the convex portions 241 of the catalyst layer 24 are made to face the current collector 22. , is arranged at a corresponding position between the first convex portion 431 and the second convex portion 432 of the packaging material 41. By pressing at room temperature in this state, the protrusions 241 of the catalyst layer 24 fit between the first anchor protrusions 214 and the second anchor protrusions 215, and are bonded without gaps.

As a result, in the metal-air battery 1, high adhesiveness can be obtained at each interface of the air electrode 2, and the protrusions 241 allow the water-repellent film 21 and the catalyst layer 24 to be bonded without any gaps, and the electrolyte The occurrence of infiltration and peeling can be more effectively suppressed.

(Example)
FIG. 19 is a characteristic chart showing evaluation results for the metal-air battery 1 according to the present disclosure. Here, we will discuss Examples 1 to 5 in which the structure of the sealing area provided in the packaging material constituting the exterior body of the metal-air battery is the structure explained in each of the above embodiments, and Comparative Example 1 in which the structure is conventional. Battery performance was evaluated. In FIG. 20, the schematic structures of the sealing regions in Examples 1 to 5 and Comparative Example 1 are shown as structures A to F, respectively.

In Examples 1 to 5 and Comparative Example 1, MnO ₂ (manganese dioxide, manufactured by Chuo Denki Kogyo, trade name: CMD-K200) was used as the catalyst, and 1.5 times the weight of carbon black was added. The mixture was mixed in a ball mill (the balls used were Zr and had a diameter of 4 mm) for 12 hours. A binder (manufactured by Daikin, PTFE dispersion "D-210C", solvent: water, solid content concentration: 60 wt%) with a weight ratio of 25% of the total solid content was added to the mixture of the catalyst and carbon black. Add enough water to make the solid content concentration 50 wt% and knead with a pressure kneader to make a mixture. Form the mixture into a sheet with a roll mill and dry it to create a catalyst layer. did.

As shown in FIG. 20, the structure of the sealing region is a structure A in Example 1, which is similar to the form shown in Embodiment 1, and a structure B, which is similar to the form shown in Embodiment 2, in Example 2. In Example 3, the structure C is the same as that shown in Embodiment 3, in Example 4, structure D is the same as that shown in Embodiment 4, and in Example 5, the structure D is the same as that shown in Embodiment 5. In Comparative Example 1, a structure F, which is the conventional form shown in FIG. 21B, was used.

As evaluation items, the initial voltage was compared with the voltage after storage after storage for 21 days in a 60° C. environment, and the voltage maintenance rate was evaluated by a current test. For storage, a jig that holds the metal-air battery 1 in a constantly ventilated state is used, and the capacity retention rate is evaluated by comparing the initial capacity and the capacity after storage after 21 days of storage in a 60°C environment. did. Furthermore, the presence or absence of electrolyte intrusion into the air electrode after storage was visually confirmed to evaluate the state of water intrusion. As a comprehensive evaluation of battery performance, the battery performance was evaluated in three stages as ○, Δ, and × based on the voltage maintenance rate, capacity retention rate, and presence or absence of water immersion.

As a result, in Comparative Example 1 in which the sealing area was configured as Structure F, most of the area was flooded with water after being stored for 21 days, and the capacity retention rate was reduced to 44.5%. On the other hand, in Example 1 in which the sealing area was of structure A, water intrusion occurred only partially. Further, in Examples 2 to 5 in which the sealing area was structured B to E, almost no water intrusion was observed, and good results were obtained. In particular, in Examples 2 to 5, the capacity retention rate was 90% or more, and compared to Comparative Example 1, there was no large change in the initial capacity and the capacity after storage, indicating that the battery performance was extremely good. Ta.

In any of the embodiments of Examples 1 to 5, the first convex portion and the second convex portion (including the third convex portion in Example 4) provided in the sealing region are advantageous. This can be said to be a structure in which the adhesion between the water-repellent film, the current collector, and the catalyst layer is improved, and peeling at the interface can be suppressed. Furthermore, from the evaluation results of Examples 2 to 5, it can be said that structures B to E, in which the convex portion on the outer peripheral side acts effectively, are more preferable.

From the above, it has been confirmed that in the metal-air battery 1 according to the present embodiment, it is possible to increase the interfacial adhesion of the air electrode, suppress the occurrence of peeling, and ensure good battery characteristics. It can be said that it becomes possible to solve the problem of output reduction.

It should be noted that the embodiments disclosed herein are illustrative in all respects, and are not the basis for a limited interpretation. Therefore, the technical scope of the present disclosure is not to be interpreted only by the above-described embodiments, but is defined based on the claims. In addition, all changes within the meaning and scope of the claims are included.

1 Metal air battery 2 Air electrode 201 First air electrode 202 Second air electrode 21 Water-repellent film 211 Backing layer 212 Water-repellent layer 213 Outer edge 214 First anchor projection 215 Second anchor projection 216 Third anchor projection 22 Current collector 23 Air electrode lead portion 24 Catalyst layer 241 Convex portion 3 Metal electrode 31 Negative electrode current collector 32 Negative electrode lead portion 4 Exterior body 41 Packaging material 41a Outer surface 41b Inner surface 411 Base material layer 412 Heat-fusible film layer 42 Opening 43 Welding area 431 First convex part 432 Second convex part 433 Third convex part 434 Concave part 435 First inner convex part 436 Second inner convex part 437 Third inner convex part 50 Welding horn

Claims (8)

A metal air battery comprising an air electrode including a water-repellent film and a metal electrode in an exterior body having an opening,
The exterior body is provided with a continuous welded area in which the water-repellent film is welded to a peripheral edge of the opening,
The welding region has a convex portion that bulges outward of the exterior body at least on an outer peripheral side and an inner peripheral side of the welding region,
The metal-air battery is characterized in that the air electrode is arranged so as to overlap the convex portion on the outer peripheral side with the water-repellent film interposed therebetween. The metal air battery according to claim 1,
A metal-air battery characterized in that the convex portion on the outer circumferential side is thicker than the convex portion on the inner circumferential side. The metal air battery according to claim 1,
The metal-air battery, wherein the convex portion on the outer peripheral side is arranged so that a portion thereof protrudes from the outer edge of the air electrode. The metal air battery according to claim 1,
A metal-air battery, wherein a plurality of the welding regions are provided on a peripheral edge of the opening. The metal air battery according to claim 4,
The plurality of welded regions are provided adjacent to each other, and the convex portion on the inner peripheral side of one adjacent welded region and the convex portion on the outer peripheral side of the other welded region are integrally provided. A metal-air battery characterized by: The metal air battery according to claim 1,
The air electrode is a laminate of a current collector and a catalyst layer,
The metal-air battery is characterized in that the catalyst layer includes a convex portion corresponding to a concave portion between the convex portion on the outer circumferential side and the convex portion on the inner circumferential side. In the metal air battery according to any one of claims 1 to 6,
The air electrode is a laminate of a current collector and a catalyst layer, the current collector is a porous material,
A metal-air battery, wherein the water-repellent film is provided on the catalyst layer side of the current collector. A method for manufacturing a metal-air battery comprising a water-repellent film, an air electrode, and a metal electrode in an exterior body having an opening, the method comprising:
The water-repellent film is welded to the peripheral edge of the opening of the exterior body to provide a welded area, and a convexity bulging outward of the exterior body is provided at least on the outer circumferential side and the inner circumferential side of the welded area. A shaped part is provided,
A method for manufacturing a metal-air battery, characterized in that the air electrode is arranged so as to overlap the convex portion on the outer peripheral side with the water-repellent film interposed therebetween.

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