Battery

Abstract

To suppress hydrogen generation in an externally-packaged body to prevent liquid from leaking from the externally-packaged body.SOLUTION: A positive electrode 3, a metal negative electrode 4 and an alkaline aqueous solution are arranged in an externally-packaged body 2, where the metal negative electrode 4 includes, as a negative-electrode active material, a first metal material including at least any one kind of metallic elements of magnesium, aluminum, iron and zinc. The metal negative electrode 4 is provided with a negative-electrode lead terminal 5 extending from inside to outside of the externally-packaged body 2. The negative-electrode lead terminal 5 comprises an uneven-shape part 51 having a second metal material including at least one kind of metal elements selected from a group constituted of a group 11 to a group 15 of the periodic table.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a battery having a positive electrode, a metal negative electrode, and an alkaline aqueous solution disposed within an outer casing. [Background technology]

[0002] In recent years, laminated batteries, which are batteries configured with a positive electrode, a metal negative electrode, and an electrolyte disposed inside a housing, have come into practical use. The housing of laminated batteries often uses a heat-sealable resin container, and the electrolyte is generally an alkaline aqueous solution such as a strongly alkaline potassium hydroxide solution.

[0003] In this type of battery, the positive electrode and the metal negative electrode are provided with lead terminals that extend from the inside to the outside of the outer casing, and the outer casing is welded and sealed with these lead terminals sandwiched between them. However, there is a risk that the adhesion between the outer surface of the lead terminals and the welding layer of the outer casing may decrease due to changes in internal pressure or the influence of the contained electrolyte. To improve the sealing of the outer casing, for example, it is possible to provide irregularities on the outer surface of the lead terminals.

[0004] For example, Patent Document 1 discloses a battery that includes a power generating element consisting of a positive electrode, a negative electrode, and a separator, a non-aqueous electrolyte solution, and flat metal lead terminals electrically connected to the positive electrode and the negative electrode, all wrapped in a polymer film material, with the front and back surfaces of the lead terminals having an uneven surface. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-243939 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in a battery having the above-described conventional configuration, simply providing an uneven surface on the surface of the lead terminal increases the surface area of the lead terminal due to the uneven surface, which increases the contact area between the lead terminal placed inside the outer casing and the electrolyte (alkaline aqueous solution) contained in the outer casing, causing problems such as the progress of the decomposition reaction of the electrolyte and accelerating hydrogen generation. Furthermore, such hydrogen generation increases the internal pressure of the outer casing, which tends to reduce the adhesion between the lead terminal and the outer casing, potentially causing leakage, etc.

[0007] The present disclosure has been made in consideration of the above-mentioned problems, and its purpose is to provide a battery that can suppress hydrogen generation and prevent leakage from the outer casing while increasing the adhesive strength between the outer casing and the lead portion that extends from the inside to the outside of the outer casing. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems, the present disclosure provides a battery in which a positive electrode, a metal negative electrode, and an alkaline aqueous solution are disposed within an outer casing, wherein the metal negative electrode contains a first metal material containing at least one metal element selected from magnesium, aluminum, iron, and zinc as a negative electrode active material, the metal negative electrode is provided with a foil-like lead portion that extends from the inside to the outside of the outer casing, a portion of which is adhered to the outer casing, the lead portion has an uneven portion on its outer surface, and the uneven portion is made of a second metal material containing at least one metal element selected from the group consisting of Groups 11 to 15 of the periodic table, or has a surface layer of the second metal material containing at least one metal element selected from the group consisting of Groups 11 to 15 of the periodic table.

[0009] In the battery having the above configuration, the surface layer preferably contains metal particles or metal oxide particles of the second metallic material, and the second metallic material preferably contains any of copper, zinc, tin, and bismuth.

[0010] In the battery having the above configuration, the lead portion preferably contains zinc as the second metal material in the interior region of the outer casing.

[0011] In the battery having the above configuration, it is preferable that the lead portion has an inner main body layer formed of a metal element different from the metal element of the second metal material.

[0012] In the battery having the above configuration, the outer casing may include a sealing member between the outer casing and the lead portion, and the lead portion may be fixed to the outer casing via the sealing member.

[0013] In the battery having the above configuration, the positive electrode may be an air electrode, and the metal negative electrode may be a zinc negative electrode. [Effects of the Invention]

[0014] According to the battery of the present disclosure, it is possible to suppress hydrogen generation while increasing the adhesive strength between the outer casing and the lead portion extending from the inside to the outside of the outer casing, thereby preventing liquid leakage from the outer casing. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a perspective view schematically illustrating a metal-air battery, which is a battery according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is an enlarged front view showing an upper portion of the metal-air battery. [Figure 3] FIG. 2 is a cross-sectional view showing an example of the configuration of the metal-air battery. [Figure 4] 3 is an enlarged view of the internal structure of the upper part of the metal-air battery, corresponding to the cross section taken along line AA in FIG. 2. [Figure 5] FIG. 2 is an enlarged cross-sectional view schematically showing a negative electrode lead terminal in the metal-air battery. [Figure 6] FIG. 3 is an enlarged cross-sectional view schematically showing another example of a negative electrode lead terminal in the metal-air battery. [Figure 7A]3 is an enlarged cross-sectional view schematically showing an example of the configuration of a concave-convex portion in a first embodiment of the negative electrode lead terminal. FIG. [Figure 7B] 4 is an enlarged cross-sectional view schematically showing another example of the configuration of the uneven portion in the first embodiment of the negative electrode lead terminal. FIG. [Figure 8] FIG. 4 is an enlarged cross-sectional view schematically showing still another example of the configuration of the uneven portion in the first embodiment of the negative electrode lead terminal. [Figure 9A] FIG. 4 is an enlarged cross-sectional view schematically showing an example of the configuration of a concave-convex portion in a second embodiment of the negative electrode lead terminal. [Figure 9B] FIG. 6 is an enlarged cross-sectional view schematically showing another example of the configuration of the concave-convex portion in the second embodiment of the negative electrode lead terminal. [Figure 10] FIG. 4 is an enlarged cross-sectional view showing a configuration example of a third embodiment of the negative electrode lead terminal. [Figure 11A] FIG. 1 is a perspective view schematically illustrating a metal-air battery, which is a battery according to another embodiment of the present disclosure. [Figure 11B] FIG. 2 is an enlarged cross-sectional view showing an upper portion of the metal-air battery. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, a metal-air battery 1 will be described as an example of a battery according to the present disclosure with reference to the drawings.

[0017] (metal-air battery) FIG. 1 is a perspective view that schematically shows a metal-air battery 1 that is a battery according to an embodiment of the present disclosure, and FIG. 2 is a front view that shows an enlarged view of the upper part of the metal-air battery 1. As shown in FIG.

[0018] The metal-air battery 1 is constructed by housing a positive electrode 3 and a metal negative electrode 4 in an outer casing 2, which is a bag-shaped exterior case. The positive electrode 3 is provided with a positive electrode lead terminal (lead portion) 7 extending from the inside of the outer casing 2 to the outside. The metal negative electrode 4 is also provided with a negative electrode lead terminal (lead portion) 5 extending from the inside of the outer casing 2 to the outside. The electrolyte is an aqueous solution of an alkali metal hydroxide (alkaline aqueous solution), which is a liquid having ionic conductivity. Examples of the alkaline aqueous solution that can be used include an aqueous solution of lithium hydroxide, an aqueous solution of sodium hydroxide, and an aqueous solution of potassium hydroxide. Among these, it is particularly preferable to use an aqueous solution of potassium hydroxide, which has excellent ionic conductivity. A gelling agent or a metal oxide may be added to the electrolyte as an additive.

[0019] The outer casing 2 is a bottomed bag-like container that is prepared in advance with an open top to accommodate the positive electrode 3, the metal negative electrode 4, and the electrolyte. After accommodating the positive electrode 3 and the metal negative electrode 4, the top of the outer casing 2 is welded and sealed with the positive electrode lead terminal 7 and the negative electrode lead terminal 5 extending outside the outer casing 2.

[0020] The outer envelope 2 is preferably made of a thermoplastic resin material with excellent alkali resistance, such as a polyolefin resin film material (laminate film) such as polypropylene or polyethylene. Furthermore, the outer envelope 2 is not limited to a single-layer structure consisting of a single layer of the resin film material, but may also have a multi-layer structure in which multiple layers are laminated.

[0021] As shown in Fig. 2, the upper portion of the outer casing 2 is welded and sealed to form a welded portion 21. At the welded portion 21, the outer casing 2 is adhered to the foil-shaped positive electrode lead terminal 7 and negative electrode lead terminal 5, with these lead terminals 7 and 5 sandwiched between them. The positive electrode lead terminal 7 and negative electrode lead terminal 5 are metal foil conductors, and are provided on the positive electrode 3 and the metal negative electrode 4, respectively, and extend outside the outer casing 2. For the positive electrode 3, it is preferable to use, for example, nickel foil as the positive electrode lead terminal 7.

[0022] FIG. 3 is a cross-sectional view showing an example of the configuration of a metal-air battery 1. For example, the metal-air battery 1 can be configured as shown in FIG. 3. In this case, the metal-air battery 1 includes a positive electrode 3, a metal negative electrode 4, a separator 11, and a water-repellent film 12 within an outer casing 2. The separator 11 is disposed opposite the resin film material that constitutes the outer casing 2, and its peripheral edge is adhered to the peripheral edge of the resin film material. The positive electrode 3 is housed together with the water-repellent film 12 between the separator 11 and one of the resin film materials having an opening 22 formed therein, thereby constituting an air electrode. This opening 22 serves as an air intake port.

[0023] The positive electrode 3 serving as an air electrode includes a current collector 31 and a catalyst layer 32 in contact with the current collector 31, and has oxygen reduction ability and oxygen generation ability. A positive electrode lead terminal 7 is provided on the current collector 31 and extends outward. The catalyst layer 32 includes at least an air electrode catalyst. The air electrode catalyst is a catalyst that has at least oxidation-reduction ability. Examples of the air electrode catalyst include conductive carbon such as ketjen black, acetylene black, denka black, carbon nanotubes, and fullerene, as well as metals, metal oxides, metal hydroxides, and metal sulfides.

[0024] The metal negative electrode 4 is housed between the other resin film material constituting the outer casing 2 and the separator 11 in a state in which a current collector 41 having a negative electrode lead terminal 5 and an active material layer 42 containing a negative electrode active material electrically connected to the current collector 41 are laminated. The negative electrode lead terminal 5 is provided on the current collector 41. The current collector 41 and particulate negative electrode active material (e.g., zinc or zinc oxide) may be added separately and then laminated. Alternatively, the metal negative electrode 4 may include the current collector 41 and a colloidal slurry in which particles of the negative electrode active material and an electrolyte are mixed.

[0025] (metallic anode) In the metal negative electrode 4, the current collector 41 forms a conductive path for current from the negative electrode material. The current collector 41 has, for example, a flat plate or sheet shape. The current collector 41 may be a current collector with a three-dimensional mesh structure made of foamed metal, expanded metal, punched metal, felt-like metal fiber, or the like.

[0026] The metal negative electrode 4 contains a first metal material containing at least one metal element selected from the group consisting of magnesium, aluminum, iron, and zinc as a negative electrode active material. When these metal elements are used as the negative electrode active material, an aqueous solution that does not pose a risk of ignition can be used as the electrolyte.

[0027] The negative electrode lead terminal 5 provided on the current collector 41 extends from the inside to the outside of the outer casing 2, a portion of which is adhered to the outer casing 2, and is further formed as a foil-like body exposed to the outside of the outer casing 2.

[0028] Fig. 4 is an enlarged cross-sectional view showing the internal structure of the upper part of the metal-air battery 1, and is a view equivalent to the cross section AA in Fig. 2. In Fig. 4, the metal-air battery 1 and the negative electrode lead terminal 5 are shown arranged sideways.

[0029] 4, the negative electrode lead terminal 5 is disposed between the outer envelopes 2 and extends from the inside to the outside (to the right in FIG. 4) of the outer envelope 2. In the illustrated embodiment, the negative electrode lead terminal 5 has an uneven portion 51 on the outer surface of the negative electrode lead terminal 5 facing the inner surface of the outer envelope 2, and a main body layer 52 inside the uneven portion 51.

[0030] The uneven portion 51 is provided in at least a part of the extending direction (length direction) of the negative electrode lead terminal 5. In particular, the uneven portion 51 is preferably provided in a region that is disposed inside the outer envelope 2 and that includes the weld portion 21. The uneven portion 51 may be provided on both the front and back surfaces of the negative electrode lead terminal 5, or on only one of the surfaces. In the embodiment shown in FIG. 4, the uneven portion 51 is provided on both the front and back surfaces of the negative electrode lead terminal 5.

[0031] (First form of negative electrode lead terminal 5) In the metal-air battery 1 according to the present disclosure, the uneven portion 51 provided on the negative electrode lead terminal 5 of the metal negative electrode 4 is provided so as to have a second metallic material containing at least one metallic element selected from the group consisting of Groups 11 to 15 of the periodic table. Various embodiments of the second metallic material in the uneven portion 51 are possible, and first and second embodiments of these will be described below.

[0032] FIG. 5 is an enlarged cross-sectional view schematically showing a part of the negative electrode lead terminal 5 shown in FIG. 4, and FIG. 6 is an enlarged cross-sectional view schematically showing a part of another example of the negative electrode lead terminal 5.

[0033] The negative electrode lead terminal 5 has an outer surface provided with an uneven portion 51. The main body layer 52 is a portion that constitutes the center of the negative electrode lead terminal 5 in the thickness direction (the vertical direction in FIG. 4).

[0034] In the first form of the negative electrode lead terminal 5, the uneven portion 51 has an uneven portion 511 and a metal particle layer 512 (or metal plating layer 513) on the surface thereof. The uneven portion 511 is formed integrally with the surface of the main body layer 52 in a mountain-valley shape. The metal particle layer 512 (or metal plating layer 513) is provided so as to cover the uneven portion 511. The metal particle layer 512 (or metal plating layer 513) is a surface layer having a second metal material containing at least one metal element selected from the group consisting of Groups 11 to 15 of the periodic table.

[0035] In this case, the uneven portion 511 can be formed by various chemical or physical processes, such as adjusting the electrodeposition conditions on the metal foil constituting the main layer 52 to encourage the growth of metal crystals in an uneven shape on the outer surface during the manufacture of the negative electrode lead terminal 5, or performing an etching process or a blasting process on the outer surface of the metal foil.

[0036] Also, as shown in FIG. 6, the uneven portion 51 of the negative electrode lead terminal 5 may be configured to have an uneven portion 511 formed by adhering metal particles to the surface of the main body layer 52, and a metal particle layer 512 (or a metal plating layer 513) as a surface layer covering the uneven portion 511.

[0037] The metal particle layer 512 covering the uneven portion 511 can be formed by adding metal particles or metal oxide particles containing a second metal material. From the viewpoint of electronic conductivity in the negative electrode lead terminal 5, it is more preferable that the metal particle layer 512 be made of metal particles rather than metal oxide particles.

[0038] As the surface layer of the uneven portion 51, a metal plating layer 513 containing a second metal material may be provided instead of the metal particle layer 512. Furthermore, both the metal particle layer 512 and the metal plating layer 513 may be provided on the uneven portion 51.

[0039] The main body layer 52 that forms the inside of the negative electrode lead terminal 5 ensures the mechanical strength of the negative electrode lead terminal 5 and is responsible for electronic conductivity. In contrast, the uneven portion 51 is configured to suppress hydrogen generation due to contact with the alkaline aqueous solution that serves as the electrolyte, by using the metal particle layer 512 or the metal plating layer 513. In addition, the uneven portion 51 and the main body layer 52 are preferably formed from an alkali-resistant metal material.

[0040] More specifically, the metal particle layer 512 or the metal plating layer 513 of the concave-convex portion 51 of the negative electrode lead terminal 5 contains a second metal material containing at least one metal element selected from the group consisting of Groups 11 to 15 of the periodic table. As described above, when the metal negative electrode 4 contains a first metal material containing at least one metal element selected from magnesium, aluminum, iron, and zinc as the negative electrode active material and an aqueous solution is used as the electrolyte, a side reaction may occur in which the electrolyte decomposes, generating hydrogen gas. In contrast, elements of Groups 11 to 15 of the periodic table have a relatively high hydrogen overvoltage. Therefore, when the metal particle layer 512 or the metal plating layer 513 of the concave-convex portion 51 contains the second metal material, the side reaction can be suppressed.

[0041] The second metal material of metal particle layer 512 or metal plating layer 513 is a metal element selected from the group consisting of Groups 11 to 15 of the periodic table, such as copper (Cu), zinc (Zn), indium (In), tin (Sn), antimony (Sb), thallium (Tl), lead (Pb), and bismuth (Bi), and at least one of these metal elements is preferred. Among these, antimony, thallium, and lead are toxic, and indium is expensive. Therefore, it is preferred to use copper, zinc, tin, or bismuth, which are inexpensive, have low toxicity, and can be used safely, as the second metal material for metal particle layer 512 or metal plating layer 513, and it is particularly preferred to use zinc or tin, which have particularly high hydrogen overvoltage.

[0042] In contrast, the main layer 52 of the negative electrode lead terminal 5 is preferably formed using one of the metal elements copper (Cu), zinc (Zn), brass (Cu / Zn alloy), nickel (Ni), and gold (Au) as a material. Of these, nickel is prone to generating hydrogen, gold is expensive, and zinc cannot be expected to have sufficient mechanical strength. Therefore, it is more preferable to use a metal material containing copper or brass, which has excellent mechanical strength and electronic conductivity, for the main layer 52.

[0043] Furthermore, while metal particle layer 512 or metal plating layer 513 is made of such a second metal material, main body layer 52 may also be made of the same second metal material. However, since concave-convex portion 51 and main body layer 52 have different roles as described above, it is more preferable that main body layer 52 be made of a metal element different from the metal element making up the second metal material of metal particle layer 512 or metal plating layer 513.

[0044] Therefore, an example of a preferred combination of the metal particle layer 512 or metal plating layer 513 of the uneven portion 51 of the negative electrode lead terminal 5 and the main body layer 52 is a foil-like body made of copper, with the uneven portion 511 formed on its outer surface, and the metal particle layer 512 or metal plating layer 513 covering the uneven portion 511 further containing tin.

[0045] Furthermore, the uneven portion 51 is provided at the welded portion 21 so as to increase the adhesive strength between the negative electrode lead terminal 5 and the outer cover 2. The uneven portion 51 preferably has a surface roughness (arithmetic mean roughness) Ra in the range of 0.4 μm to 3.0 μm (preferably 1.0 μm to 2.0 μm) or a ten-point mean surface roughness Rz in the range of 2.0 μm to 15.0 μm (preferably 7.0 μm to 10.0 μm).

[0046] If the surface roughness is smaller than this range, the sealing performance of the adhesive interface between the outer envelope 2 and the negative electrode lead terminal 5 will be reduced, which may result in leakage of the liquid to the outside of the outer envelope 2. If the surface roughness is larger than this range, the area of contact between the negative electrode lead terminal 5 and the electrolyte will be large, which may result in an insufficient reduction in the amount of hydrogen generated. Therefore, it is preferable that the surface roughness of the uneven portion 51 be within the above range.

[0047] The surface roughness of the uneven portion 51 is measured by determining the arithmetic mean roughness and the maximum height roughness (JIS B 0601:2001) using a stylus surface roughness measuring instrument (JIS B 0651:2001). As the stylus surface roughness measuring instrument, for example, the stylus surface roughness measuring instrument SE-3500 manufactured by Kosaka Laboratory can be used.

[0048] 7A, 7B, and 8 are enlarged cross-sectional views each showing a schematic configuration example of the concave-convex portion 51 in the negative electrode lead terminal 5. FIG.

[0049] 7A, the negative electrode lead terminal 5 has uneven portions 511 on both the front and back surfaces (both the top and bottom surfaces in FIG. 7A) as the uneven portion 51, and a metal particle layer 512 is provided so as to cover the uneven portions 511. For example, the main body layer 52 of the negative electrode lead terminal 5 is a foil-like body made of copper, and the uneven portions 511 are formed on the outer surface by a chemical treatment or a physical treatment, and metal particles or metal oxide particles containing copper are attached to the uneven portions 511 to provide the metal particle layer 512.

[0050] 7B , the negative electrode lead terminal 5 may have a configuration in which the uneven portion 51 is formed by providing uneven portions 511 on both the front and back surfaces of a main body layer 52 made of copper, and a metal plating layer 513 is provided to cover the uneven portion 511. Since the metal particle layer 512 or the metal plating layer 513 is provided on the uneven portion 511 formed on the main body layer 52 by a chemical treatment or a physical treatment, the surface roughness of the uneven portion 51 can be increased, and the sealing property of the adhesive interface with the outer envelope 2 can be improved.

[0051] 8 , the negative electrode lead terminal 5 may have both a metal particle layer 512 and a metal plating layer 513 provided on the concave-convex portions 511 on both the front and back surfaces of the main body layer 52, thereby forming the concave-convex portion 51. In this case, for example, the negative electrode lead terminal 5 has the main body layer 52 formed of a foil made of copper, the concave-convex portion 51 having peak-valley shapes is provided as the concave-convex portion 51, the metal particle layer 512 containing copper is provided so as to cover the concave-convex portion 511, and further the metal plating layer 513 containing tin is provided so as to cover the metal particle layer 512.

[0052] In the example shown in Fig. 8, uneven portion 51 has a metal particle layer 512 provided on hill-valley shaped uneven portion 511, so that the particles of metal particle layer 512 form an uneven shape with constricted portions. Both Fig. 7B and Fig. 8 have metal plating layer 513 as uneven portion 51, but compared to the example shown in Fig. 7B, uneven portion 51 shown in Fig. 8 can be more firmly adhered to outer envelope 2.

[0053] Furthermore, as shown in Figure 8, by forming a metal plating layer 513 containing tin so as to cover the metal particle layer 512, the main body layer 52 can be more reliably covered compared to the case of Figure 7A where there is no metal plating layer 513, and therefore hydrogen generation due to contact of the main body layer 52 with an alkaline aqueous solution can be effectively prevented.

[0054] 4, the uneven portion 51 preferably has grooves formed along a direction (a direction intersecting the plane of the paper in the figure) that intersects with the length direction of the negative electrode lead terminal 5 (the left-right direction in the figure), which can more effectively prevent liquid leakage. Also, as shown in FIG. 6, the uneven portion 51 has an uneven shape with constricted portions, whereby the uneven portion 511 can be more firmly adhered to the outer envelope 2.

[0055] In the negative electrode lead terminal 5, when the metal foil constituting the main body layer 52 and the uneven portion 511 are integrally formed, it is possible to prevent damage to the uneven shape of the uneven portion 511 due to wear during the manufacturing process, etc. Therefore, the uneven shape of the uneven portion 51, which includes the uneven portion 511 and the metal particle layer 512 or the metal plating layer 513, is maintained until it is welded to the outer case 2, and it is possible to favorably adhere the negative electrode lead terminal 5 to the outer case 2 and seal the outer case 2.

[0056] The main layer 52 of the negative electrode lead terminal 5 can be made of a metal foil having a width of 5 to 20 mm and a thickness of 20 to 200 μm. More preferably, the width is 10 to 15 mm and the thickness is 35 to 100 μm. If the width or thickness is less than the above ranges, the resistance of the negative electrode lead terminal 5 increases. If the width or thickness exceeds the above ranges, leakage may occur even if the concave-convex portion 51 is provided on both the front and back surfaces of the negative electrode lead terminal 5.

[0057] Furthermore, in the negative electrode lead terminal 5, the main body layer 52 and the uneven portion 51 are not necessarily made of different second metal materials, and the layers may be made to have different thicknesses. In this case, the thickness of the main body layer 52 is set to 20 to 100 μm as described above, while the thickness of the metal particle layer 512 and / or the metal plating layer 513 of the uneven portion 51 is preferably set to 5 to 25 μm, and is preferably smaller than the thickness of the main body layer 52.

[0058] The negative electrode lead terminal 5 configured as described above can increase the adhesive strength with the outer casing 2 due to the uneven shape of the uneven portion 51, and can suppress hydrogen generation due to the metal particle layer 512 or metal plating layer 513 of the uneven portion 51. Therefore, the metal-air battery 1 can be configured such that leakage of alkaline aqueous solution from the welded portion 21 where the negative electrode lead terminal 5 extends is prevented, and the outer casing 2 is stably sealed.

[0059] (Second form of negative electrode lead terminal 5) In the metal-air battery 1 according to an embodiment of the present disclosure, the uneven portion 51 of the negative electrode lead terminal 5 may be configured to have an uneven shape made of metal particles or metal oxide particles of the second metal material attached to the outer surface of the main body layer 52, and to have the second metal material.

[0060] FIG. 9A is an enlarged cross-sectional view schematically showing a part of the negative electrode lead terminal 5, and FIG. 9B is an enlarged cross-sectional view schematically showing a part of another example of the negative electrode lead terminal 5. As shown in FIG.

[0061] As shown in FIG. 9A, in the second form of the negative electrode lead terminal 5, an uneven portion 51 is provided on the outer surface, and the uneven portion 51 itself is made of a second metal material containing at least one metal element selected from the group consisting of Groups 11 to 15 of the periodic table.

[0062] That is, metal particle layers 514 formed by adhering metal particles or metal oxide particles of a second metallic material containing at least one metallic element selected from the group consisting of Groups 11 to 15 of the periodic table are provided on both the front and back surfaces of the negative electrode lead terminal 5 as the uneven portion 51. In this case, the uneven portion 511 shown in the first embodiment is not provided, and the uneven shape is imparted by the particles of the metal particle layer 514 of the second metallic material adhered to the main body layer 52, thereby forming the uneven portion 51.

[0063] Furthermore, as shown in FIG. 9B, the negative electrode lead terminal 5 may be provided with, as the uneven portion 51, both a metal particle layer 514 having metal particles or metal oxide particles of a second metal material attached to the outer surface of the main body layer 52, and a metal plating layer 515 of the second metal material.

[0064] Even in the negative electrode lead terminal 5 having such a configuration, the uneven shape of the uneven portion 51 can increase the adhesive strength with the outer casing 2, and the second metal material of the uneven portion 51 acts to effectively suppress hydrogen generation due to contact with the alkaline aqueous solution of the electrolyte. Therefore, the metal-air battery 1 can be configured so that the alkaline aqueous solution is prevented from leaking from the welded portion 21 where the negative electrode lead terminal 5 extends, and the outer casing 2 is stably sealed.

[0065] (Third form of negative electrode lead terminal 5) 1 and 2, in the metal negative electrode 4, the negative electrode lead terminal 5 is attached to the welded portion 21 of the outer case 2 and extends from the inside to the outside of the outer case 2. Therefore, in at least the region inside the welded portion 21 within the outer case 2, the negative electrode lead terminal 5 is not attached to the outer case 2, and therefore is not limited to the configuration described above. In the region inside the welded portion 21, the second metal material preferably contains zinc.

[0066] FIG. 10 is an enlarged cross-sectional view showing another example of the internal structure of the upper part of the metal-air battery 1, and is a cross-sectional view corresponding to the AA cross-section in FIG.

[0067] 10, in a third form of the negative electrode lead terminal 5, a zinc layer 516 containing zinc as the second metal material may be provided in the interior region of the outer casing 2, for example, on the outer surface of the negative electrode lead terminal 5. The zinc layer 516 may be a metal particle layer to which zinc particles are attached or a zinc metal plating layer.

[0068] The region inside the welded portion 21 of the outer casing 2 is the region that comes into contact with the alkaline aqueous solution that serves as the electrolyte. In the negative electrode lead terminal 5, this region is prone to hydrogen gas generation due to the progress of the decomposition reaction of the alkaline aqueous solution. In contrast, by providing a zinc layer 516 on the outer surface of the negative electrode lead terminal 5 in this region as shown in FIG. 10, it is possible to effectively suppress hydrogen generation.

[0069] The zinc layer 516 is preferably provided on both the front and back surfaces of the negative electrode lead terminal 5 (both the top and bottom surfaces in FIG. 10 ). The negative electrode lead terminal 5 is preferably provided with the uneven portion 51 shown in the first embodiment or the second embodiment, and the zinc layer 516 is provided so as to cover the uneven portion 51. Instead of the zinc layer 516, the metal particle layer 512 or the metal plating layer 513 of the uneven portion 51 may contain zinc as the second metal material. Note that when the uneven portion 51 is provided at least in the region to be disposed in the welded portion 21 and not in the region inside the welded portion 21, the zinc layer 516 may be provided on the outer surface of the main body layer 52.

[0070] Such zinc layer 516 can contribute as an active material during discharge, thereby increasing the discharge capacity. Furthermore, in the region of negative electrode lead terminal 5 inside welded portion 21, zinc layer 516 is provided as the outermost layer, and main layer 52 is present inside zinc layer 516, so that even if zinc layer 53 dissolves due to discharge, current can be collected by main layer 52. Furthermore, hydrogen generation due to contact with the alkaline aqueous solution of the electrolyte can be suppressed, making it possible to prevent leakage of the alkaline aqueous solution.

[0071] In the negative electrode lead terminal 5, the configuration of the uneven portion 51 is not limited to being the same on both the front and back sides of the negative electrode lead terminal 5, but can be configured in various combinations, such as being configured as shown in FIG. 8 of the first embodiment on one side and being configured as shown in FIG. 9A of the second embodiment on the other side.

[0072] Furthermore, the negative electrode lead terminal 5 may have the uneven portion 51 on not only the front and back sides (or one side) but also on the side surface, as long as it is the outer surface of the main body layer 52. In this case, the adhesion between the side surface of the negative electrode lead terminal 5 and the outer case 2 can be further improved. By providing the uneven portion 51 at least in the region corresponding to the welded portion 21, the adhesive strength between the outer case 2 and the negative electrode lead terminal 5 in the sealed region can be increased, making it possible to prevent liquid leakage. The uneven portion 51 does not necessarily have to be provided in the region of the negative electrode lead terminal 5 that extends outside the outer case 2. Since the portion extending outside is electrically connected to the negative electrode lead terminal 5, if the uneven portion 51 is not provided, it is possible to suppress the generation of dust due to scraping of the uneven portion 51 during connection.

[0073] Furthermore, the negative electrode lead terminal 5 does not necessarily need to be provided with the uneven portion 51 in a region located inside the welded portion 21 of the outer envelope 2. The region inside the welded portion 21 is in contact with the alkaline electrolyte, so if the uneven portion 51 is not present, the contact area with the alkaline electrolyte can be reduced, thereby suppressing the decomposition reaction of the alkaline aqueous solution. On the other hand, providing the uneven portion 51 over the entire front and back surfaces of the metal foil constituting the main body layer 52 of the negative electrode lead terminal 5 can be more productive than providing the uneven portion 51 only in a partial region.

[0074] (Other embodiments) The metal-air battery 1 according to the present disclosure can be embodied in various forms other than the above-described forms. For example, the metal-air battery 1 may be provided with a sealing member 6.

[0075] Fig. 11A is a perspective view schematically showing a metal-air battery 1 equipped with a sealing member 6, and Fig. 11B is an enlarged cross-sectional view showing the internal structure of the upper part of the metal-air battery 1. Note that Fig. 11B shows the metal-air battery 1 and negative electrode lead terminal 5 arranged sideways.

[0076] The negative electrode lead terminal 5 and the positive electrode lead terminal 7 are provided with sealing members 6 corresponding to the welded portions with the outer envelope 2. A certain range of the upper portion of the outer envelope 2, including the upper end portion, is welded for sealing. The welding is performed by thermal welding (heat sealing) or ultrasonic welding, and a welded portion 21 is formed on the upper portion of the outer envelope 2.

[0077] The sealing member 6 is disposed so as to overlap the welded portion 21. For example, the sealing member 6 is made of a polyolefin resin film material such as polypropylene. The sealing member 6 extends above the welded portion 21 outside the outer case 2, and also extends below the welded portion 21 inside the outer case 2. Note that the sealing member 6 only needs to be interposed between the outer case 2 and the negative electrode lead terminal 5 and the positive electrode lead terminal 7 at the welded portion 21, and may be exposed to the outside from the upper end of the outer case 2, or may be not exposed to the outside of the outer case 2.

[0078] The sealing member 6 is preferably adhered to the negative electrode lead terminal 5 in advance. As shown in FIG. 11B , the outer case 2 and the negative electrode lead terminal 5 are adhered and sealed via the sealing member 6 at the welded portion 21 of the outer case 2. The width of the positive electrode lead terminal 7 is preferably 5 to 20 mm and the thickness is preferably 20 to 200 μm, similar to the negative electrode lead terminal 5 described above, and more preferably 10 to 15 mm and 35 to 100 μm. If the width or thickness is small, there is a problem of increased resistance of the positive electrode lead terminal 7. On the other hand, if the width or thickness is too large, there is a risk of leakage even when concave-convex portions are provided on the front and back of the positive electrode lead terminal 7.

[0079] The welding conditions and adhesion conditions, such as temperature and time, are appropriate for welding the outer casings 2 together and for bonding the outer casings 2 to the negative electrode lead terminal 5 (and the positive electrode lead terminal 7). Even if the welding conditions for welding the outer casings 2 together and the adhesion conditions for bonding the outer casings 2 to the negative electrode lead terminal 5 are different, as long as the sealing member 6 is sufficiently adhered to the negative electrode lead terminal 5, welding the sealing member 6 to the outer casing 2 can reliably bond the outer casing 2 to the negative electrode lead terminal 5. Because the outer casing 2 and the sealing member 6 are welded between resin film materials, there is little chance of welding defects occurring, and the adhesive strength of the negative electrode lead terminal 5 can be increased. Furthermore, by adhering the sealing member 6 to the uneven portion 51 of the negative electrode lead terminal 5, a good adhesive interface is formed between the outer casing 2 and the negative electrode lead terminal 5 without any gaps.

[0080] With this configuration, the adhesive strength between the negative electrode lead terminal 5 and the outer casing 2 can be further increased by the uneven portion 51 and the sealing member 6, and hydrogen generation can be effectively suppressed by the action of the uneven portion 51 having the second metal material. The uneven portion 51 may be configured in either the first form or the second form. This prevents leakage of alkaline aqueous solution from the welded portion 21 where the negative electrode lead terminal 5 extends, and allows the metal-air battery 1 to be configured in such a way that the outer casing 2 is stably sealed.

[0081] The battery according to the present disclosure can be implemented in various forms other than the above-described embodiment. The application of the battery according to the present disclosure is not limited to metal-air batteries using an air cathode as the positive electrode; for example, a nickel positive electrode or the like may be used instead of the air cathode. Furthermore, the configuration of the uneven portion 51 and the sealing member 6 in the metal-air battery 1 is not limited to the above-described embodiment; they may be configured in any shape. Furthermore, the metal-air battery 1 is suitable for, for example, zinc-air batteries, magnesium-air batteries, aluminum-air batteries, and iron-air batteries, and can be applied to both primary and secondary batteries. It is particularly effective when applied to zinc-air batteries that use a highly permeable alkaline aqueous solution as the electrolyte. [Explanation of symbols]

[0082] 1. Metal-air battery (battery) 2 Outer envelope 21 Welded area 22 Opening 3 Positive electrode 31 Current collector 32 Catalyst layer 4 Metallic anode 41 Current collector 42 Active material layer 5 Negative electrode lead terminal (lead part) 51 Uneven part 511 Uneven part 512 Metal particle layer (surface layer) 513 Metal plating layer (surface layer) 514 Metal particle layer 515 Metal plating layer 516 Zinc layer 52 Main layer 6 Sealing member 7 Positive lead terminal (lead part)

Claims

1. A battery having a positive electrode, a metal negative electrode, and an alkaline aqueous solution disposed within an outer casing, the metal negative electrode includes, as a negative electrode active material, a first metal material including at least one metal element selected from the group consisting of magnesium, aluminum, iron, and zinc; The metal negative electrode is provided with a foil-shaped lead portion that extends from the inside to the outside of the outer casing, and a part of the lead portion is adhered to the outer casing, The lead portion has an uneven portion on its outer surface, the concave-convex portion is made of a second metallic material containing at least one metallic element selected from the group consisting of Groups 11 to 15 of the periodic table, or has a surface layer of a second metallic material containing at least one metallic element selected from the group consisting of Groups 11 to 15 of the periodic table; The surface layer comprises metal particles or metal oxide particles of the second metallic material.

2. 10. The battery of claim 1, The battery, wherein the second metallic material includes any one of copper, zinc, tin, and bismuth.

3. 3. The battery of claim 2, The battery, wherein the lead portion contains zinc as the second metal material in the interior region of the outer casing.

4. The battery according to any one of claims 1 to 3, A battery characterized in that the lead portion has an inner main body layer formed of a metal element different from the metal element of the second metal material.

5. The battery according to any one of claims 1 to 4, The outer cover includes a sealing member between the outer cover and the lead portion, The battery is characterized in that the lead portion is fixed to the outer casing via the sealing member.

6. The battery according to any one of claims 1 to 5, The battery is characterized in that the positive electrode is an air electrode.

7. The battery according to any one of claims 1 to 6, The battery is characterized in that the metal negative electrode is a zinc negative electrode.

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