Battery

Abstract

The present invention provides a battery capable of suppressing leakage.　A battery according to the present invention is formed by sealing a positive electrode, a negative electrode, a separator, and an electrolyte within a sheet-like outer package. The battery is characterized in that: the outer package has a seal part that has a heat-fusible resin layer formed therein and that is fused by a heat-fusible resin of the heat-fusible resin layer; the positive electrode and the negative electrode have terminals leading from the inside of the outer package through the seal part to the outside; at least one of the terminals of the positive electrode and the negative electrode is composed of an aggregate of fibrous conductors; and the thickness of a portion located at the seal part is smaller than the thickness of a portion located further to the inner side of the outer package than the seal part.

Description

battery

[0001] The present invention relates to a battery capable of suppressing leakage.

[0002] Although various types of batteries, including air batteries and alkaline batteries, are generally button-shaped with a metal can as the exterior body or cylindrical with a cylindrical exterior can, sheet-shaped batteries with an exterior body made of a resin film have also been developed. In such batteries, the exterior body may be sealed by heat sealing using a heat-sealing resin.

[0003] Furthermore, Patent Document 1 proposes the use of a mesh-like or porous conductor for the electrode terminals that electrically connect the internal electrodes to the applicable device in a battery with an exterior body that is sealed by heat sealing. According to Patent Document 1, the heat-sealing resin in the sealing portion of the exterior body (the polymer film that constitutes it) penetrates and penetrates the gaps in the electrode terminals, making it difficult for the electrode terminals and the polymer film to peel off, thereby achieving excellent airtightness and robust mechanical strength.

[0004] Furthermore, Patent Document 1 exemplifies the electrode terminal as being made of a metal mesh, an expanded metal, a punched metal, or an aggregate of carbon fibers, and also discloses that the thickness of the electrode terminal must be equal to or thinner than the thickness of the heat-fusible polymer film layer of the sealing portion (the sum of the thicknesses of the front and back layers), and that the thickness of the resin at the sealing portion must be thicker than that of the electrode terminal in a molten state, and therefore is preferably two to three times the thickness of the electrode terminal.

[0005] Japanese Patent Application Publication No. 10-302756

[0006] However, when a substrate having straight through-holes in the thickness direction, such as the metal mesh described in the examples of Patent Document 1, is used for the electrode terminal, the molten resin easily enters the through-holes during sealing, making it easy to achieve a state in which the resin penetrates the interior of the electrode terminal from both sides.However, when the substrate has a complex bent pore structure inside, such as an aggregate of carbon fibers, it is difficult for the molten resin to penetrate into the interior of the substrate, making it difficult to achieve a sealed state in which the resin penetrates the interior of the electrode terminal.In particular, when the substrate is used as a current collector for an electrode that fills and holds an active material inside, and a part of the substrate serves as the electrode terminal, the thickness of the substrate needs to be thick, for example, 120 μm or more, to ensure a certain level of capacity, and the thickness of the terminal also increases accordingly, making the above problem more likely to occur.

[0007] Furthermore, detailed investigation of batteries with such configurations revealed that the sealing performance was reduced, and when the battery was pressed and the internal pressure increased, the electrolyte was more likely to flow inside the electrode terminal of the sealing portion, causing leakage.

[0008] As described in Patent Document 1, it is possible to improve sealing performance to some extent by making the thickness of the resin at the sealing portion two to three times the thickness of the electrode terminal. However, if the thickness of the heat-fusible polymer film layer of the exterior body is increased to fall within the above range, the overall thickness of the battery becomes too thick.

[0009] The present invention has been made in consideration of the above circumstances, and its purpose is to provide a battery that can improve sealing properties and suppress leakage from the terminals when an aggregate of fibrous conductors having a certain thickness or more is used as an electrode terminal, without making the thickness of the heat-sealable resin layer of the outer casing thicker than necessary.

[0010] The battery of the present invention is characterized in that a positive electrode, a negative electrode, a separator, and an electrolyte are sealed within an exterior body, the exterior body having a heat-sealable resin layer formed on the inside and a seal portion fused by the heat-sealable resin of the heat-sealable resin layer, the positive electrode and the negative electrode having terminals that lead from the inside of the exterior body to the outside via the seal portion, at least one of the positive electrode terminal and the negative electrode terminal being composed of an aggregate of fibrous conductors, and the thickness of the portion located at the seal portion being smaller than the thickness of the portion located inside the exterior body relative to the seal portion.

[0011] In this specification, "aggregate of fibrous conductors" means a sheet formed by assembling fibrous conductors without being woven like a fabric or a net, similar to a resin nonwoven fabric, and has voids and reduces in thickness when compressed.

[0012] According to the present invention, it is possible to provide a battery capable of suppressing leakage.

[0013] It is a plan view showing a schematic example of an example of a battery of the present invention. It is a cross-sectional view taken along line II in Fig. 1. It is an enlarged view of a part of Fig. 2. It is an explanatory diagram of a sample for measuring the peel strength of a seal part in an exterior body.

[0014] An example of a battery of the present invention is shown schematically in Figures 1, 2, and 3. The battery shown in Figures 1, 2, and 3 is an example of a battery equipped with a sheet-like outer casing (a sheet-like battery), with Figure 1 being a plan view thereof, Figure 2 being a cross-sectional view taken along line II in Figure 1, and Figure 3 being an enlarged view of a portion of Figure 2.

[0015] 2 , in battery 10, positive electrode 20, separator 40, negative electrode 30, and an electrolyte (not shown) are housed in sheet-like outer casing 50. Sheet-like outer casing 50 is composed of two resin sheets having heat-sealable resin layers 52 on their inner surfaces, and the outer peripheral edges of these resin sheets are sealed to form seal portions 51 fused with the heat-sealable resin of heat-sealable resin layer 52, thereby sealing the interior.

[0016] A terminal 23 of the positive electrode 20 and a terminal 33 of the negative electrode 30 protrude from the upper side of the sheet-like outer casing 50 in Fig. 1. As shown in Fig. 2, the positive electrode 20 has a positive electrode active material layer 21 and a positive electrode current collector 22, and the negative electrode 30 is composed of a metal sheet that acts as a negative electrode active material.

[0017] The positive electrode terminal 23 is formed by drawing a portion of the positive electrode current collector 22, where the positive electrode active material layer 21 is not formed, to the outside of the sheet-like outer casing 50 through the seal portion 51. Although not shown, the negative electrode terminal 33 is formed by drawing a portion of the metal sheet that constitutes the negative electrode 30 to the outside of the sheet-like outer casing 50 through the seal portion 51. These terminals 23, 33 are used as external terminals for electrically connecting the battery 10 to an applicable device.

[0018] In FIG. 2 , the sheet-like outer casing 50 (the resin film constituting it) is shown as a single-layer structure except for the portion where the heat-sealable resin layer 52 is provided. However, as described below, the resin film constituting the sheet-like outer casing can also have a multilayer structure. Also, in FIG. 2 , the negative electrode 30 is also shown as a single-layer structure. However, as described below, the negative electrode can have a multilayer structure including a current collector or contain metal particles such as zinc particles. Furthermore, in the battery 10 shown in FIG. 2 , the terminal 23 of the positive electrode 20 is composed of the same single sheet as the positive electrode current collector 22. However, the separate terminal 23 and the positive electrode current collector 22 may be connected via a lead or the like.

[0019] In the battery 10, the positive electrode terminal 23 is an aggregate of fibrous conductors, and as shown in Figures 2 and 3, the thickness (vertical length in Figures 2 and 3) of the portion located at the seal portion 51 is smaller than the thickness of the portion located inside the sheet-like outer casing 50 (left side in Figures 2 and 3) relative to the seal portion 51.

[0020] In the battery of the present invention, the positive electrode terminal is an aggregate of fibrous conductors, and the portion located at the seal portion of the outer casing is compressed to have a reduced thickness compared to before sealing, and this thickness is smaller than the thickness of the portion located inside the outer casing beyond the seal portion.

[0021] When a conductive porous body such as a punched metal or a metal mesh is used for the positive electrode terminal or the negative electrode terminal, as described in Patent Document 1, the heat-fusible resin in the sealing portion penetrates into the pores of the porous body when the exterior body is heat-sealed, which is expected to have the effect of increasing the sealing strength (mechanical strength) and airtightness (sealing ability) of the exterior body.

[0022] However, when the positive electrode terminal or the negative electrode terminal is an aggregate of fibrous conductors, as described above, the pores have a complex, bent structure, and therefore, even if the exterior body is heat-sealed, the heat-sealing resin of the seal portion cannot penetrate well into the pores of the terminals. Therefore, when the battery is wrapped in a package for distribution or incorporated into an applicable device, if a load is applied to the battery, a problem may occur in which the internal electrolyte leaks out of the exterior body through the porous terminals.

[0023] Therefore, in the battery of the present invention, when the positive electrode terminal and / or negative electrode terminal are an aggregate of fibrous conductors, the thickness of the portion located in the sealed portion of the exterior body is reduced by compression compared to before sealing, making it thinner than the thickness of the portion located inside the exterior body beyond the sealed portion. In the case of an aggregate of fibrous conductors, unlike porous bodies such as punched metal or metal mesh, the portion located in the sealed portion is compressed and thinned by applying a relatively large pressure during heat sealing of the exterior body, thereby allowing the heat-sealing resin to effectively penetrate into the voids in that portion. This prevents the movement of electrolyte within the terminal. Therefore, in the battery of the present invention, while using an aggregate of fibrous conductors for the positive electrode terminal, the heat-sealing resin present in the voids of the terminal can suppress leakage of electrolyte to the outside of the exterior body through the terminal, even when a load is applied.

[0024] The battery of the present invention can be in the form of a battery having an electrolyte solution composed of an aqueous solution with water as the solvent (alkaline battery (alkaline primary battery, alkaline secondary battery, manganese battery, air battery, etc.)), or can be in the form of a battery having a nonaqueous electrolyte using a nonaqueous solvent as the electrolyte (nonaqueous electrolyte battery (nonaqueous electrolyte primary battery, nonaqueous electrolyte secondary battery)).

[0025] <Positive electrode> The positive electrode of the battery may have a structure in which a positive electrode active material layer containing a positive electrode active material and a current collector are laminated together. In addition, when the battery is an alkaline battery or a manganese battery, the positive electrode may have a structure in which a positive electrode active material layer (positive electrode mixture layer) containing a positive electrode active material, a conductive additive, a binder, etc. is provided on one or both sides of a current collector.

[0026] When the battery is an alkaline battery, usable positive electrode active materials include silver oxide (silver(I) oxide, silver(II) oxide, etc.), manganese oxides such as manganese dioxide, nickel oxyhydroxide, composite oxides of silver and cobalt, nickel or bismuth, etc. When the battery is a manganese battery, manganese oxides such as manganese dioxide are used as the positive electrode active material.

[0027] Furthermore, when the battery is a non-aqueous electrolyte battery, usable positive electrode active materials include manganese dioxide; vanadium oxide, niobium oxide, titanium oxide, sulfides such as iron disulfide; graphite fluoride; ｘ Mn ３ O ６ (0<x<2), Li ｘ MnO ２ Lithium-containing manganese oxides such as (0<x<1), Li ｘ Ti ５／３ O ４ (4 / 3≦x<7 / 3), LiMn ２ O ４ or a spinel-structured composite oxide in which some of the elements are replaced with other elements, Li １＋ｘ M １ O ２ (-0.1<x<0.1, M １ Lithium-containing composite oxides having a layered structure represented by the following: Co, Ni, Mn, Al, Mg, etc.; LiM ２ P.O. ４ (M ２ various lithium-containing composite oxides such as olivine-type compounds represented by the formula (I): Co, Ni, Mn, Fe, etc.;

[0028] The layered lithium-containing composite oxide may be LiCoO ２ Lithium cobalt oxide and LiNi １－ａ Coａ－ｂ Al ｂ O ２ (0.1≦a≦0.3, 0.01≦b≦0.2), as well as oxides containing at least Co, Ni and Mn (LiMn １／３ Ni １／３ Co １／３ O ２ , LiMn ５／１２ Ni ５／１２ Co １／６ O ２ , LiNi ３／５ Mn １／５ Co １／５ O ２ etc.) can be exemplified.

[0029] The average particle size of the positive electrode active material is preferably 0.1 μm or more, more preferably 1 μm or more, and is preferably 30 μm or less, more preferably 20 μm or less. The positive electrode active material may be primary particles or secondary particles formed by aggregation of primary particles.

[0030] The average particle diameter of the positive electrode active material and the particle size of the metal particles related to the negative electrode, which will be described later, are values ​​measured using a laser scattering particle size distribution analyzer (for example, "LA-920" manufactured by Horiba, Ltd.) by dispersing these particles in a medium that does not dissolve the particles. The average particle diameter is the particle diameter at a cumulative frequency of 50% on a volume basis (D ５０ )

[0031] The positive electrode active material layer may contain only the positive electrode active material, or may contain other components in addition to the positive electrode active material. Such components include a conductive additive, a binder, etc. That is, the positive electrode active material layer can be formed from a positive electrode mixture containing the positive electrode active material, the conductive additive, and / or the binder, etc.

[0032] Examples of the conductive additive that can be used include carbon materials such as natural graphite; carbon blacks such as acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black; and carbon fibers; as well as conductive fibers such as metal fibers; carbon fluoride; metal powders such as copper and nickel; and organic conductive materials such as polyphenylene derivatives.

[0033] In addition, the binder may be a water-insoluble resin such as an acrylic resin (such as polyacrylic ester), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), or styrene butadiene rubber (SBR), or a water-soluble resin such as polyacrylate (such as sodium polyacrylate or ammonium polyacrylate), carboxymethyl cellulose (CMC), polyvinyl alcohol (PVA), or poly-N-vinylacetamide (PNVA).

[0034] The positive electrode can be manufactured, for example, by applying a composition for forming a positive electrode active material layer (paste, slurry, etc.) in which a positive electrode active material, a conductive additive to be used as needed, a binder, etc. are dispersed in a solvent to a positive electrode current collector, drying the composition to form a positive electrode active material layer, and, if necessary, performing a pressing process such as a calendaring process.

[0035] The solvent for the positive electrode active material layer-forming composition may be water; an aqueous organic solvent such as ethanol; or a non-aqueous organic solvent such as N-methyl-2-pyrrolidone (NMP).

[0036] When a conductive additive and a binder are used together with the positive electrode active material, the proportions of these in the positive electrode mixture are preferably 80 to 98 mass % of the positive electrode active material, 1.5 to 10 mass % of the conductive additive, and 0.5 to 10 mass % of the binder.

[0037] When the battery is an air battery, the positive electrode (air electrode) may have a catalyst layer, for example, a structure in which a catalyst layer and a current collector are laminated.

[0038] The catalyst layer may contain a catalyst, a binder, and the like.

[0039] Examples of catalysts for the catalyst layer include phthalocyanine-based metal complexes; silver, platinum group metals or alloys thereof; transition metals; and Pt / IrO. ２ Platinum / metal oxides such as La １－ｘ Ca ｘ CoO ３ Perovskite oxides such as WC; carbides such as Mn ４manganese oxides such as manganese dioxide; carbon (graphite, carbon black (acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black, etc.), charcoal, activated carbon, etc.), and the like, and one or more of these may be used.

[0040] The catalyst layer preferably has a heavy metal content of 1% by mass or less. Depending on the form of the battery, it can be easily destroyed by tearing it apart by hand or the like when it is disposed of, but in the case of a positive electrode having a catalyst layer with a low heavy metal content as described above, it can be a battery with a small environmental impact even when disposed of without special treatment or the like.

[0041] The content of heavy metals in the catalyst layer referred to in this specification can be measured by X-ray fluorescence analysis. For example, the measurement can be performed using an X-ray fluorescence analyzer "ZSX100e" manufactured by Rigaku Corporation under the conditions of an excitation source of Rh 50 kV and an analysis area of ​​φ10 mm.

[0042] Therefore, it is recommended that the catalyst for the catalyst layer does not contain heavy metals, and it is more preferable to use the various carbons mentioned above.

[0043] In addition, from the viewpoint of further increasing the reactivity of the positive electrode, the specific surface area of ​​the carbon used as a catalyst is set to 200 m ２ / g or more, and ２ / g or more is more preferable, and 500m ２ / g or more is more preferable. The specific surface area of ​​carbon referred to in this specification is a value determined by the BET method in accordance with Japanese Industrial Standards (JIS) K 6217, and can be measured, for example, using a specific surface area measuring device ("Macsorb HM model-1201" manufactured by Mountech Co.) using the nitrogen adsorption method. The upper limit of the specific surface area of ​​carbon is usually 2000 mm ２ / g.

[0044] The catalyst content in the catalyst layer is preferably 20 to 70 mass %.

[0045] Examples of binders for the catalyst layer include fluororesin binders such as PVDF, PTFE, vinylidene fluoride copolymers, and tetrafluoroethylene copolymers [such as vinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), vinylidene fluoride-chlorotrifluoroethylene copolymer (PVDF-CTFE), vinylidene fluoride-tetrafluoroethylene copolymer (PVDF-TFE), and vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene copolymer (PVDF-HFP-TFE)]. Among these, tetrafluoroethylene polymer (PTFE) or copolymers are preferred, with PTFE being more preferred. The binder content in the catalyst layer is preferably 3 to 50% by mass.

[0046] In the case of a positive electrode having a catalyst layer, for example, it can be produced by mixing the catalyst, binder, etc. with water, rolling it with a roll, and bringing it into close contact with a current collector. Alternatively, it can be produced by applying a catalyst layer-forming composition (slurry, paste, etc.) prepared by dispersing the catalyst and a binder, etc. used as needed, in water or an organic solvent to the surface of the current collector, drying it, and then subjecting it to a pressing process such as calendering, as needed.

[0047] Furthermore, a porous carbon sheet, which will be described later as an example of a positive electrode current collector, can also be used as the catalyst layer. The porous carbon sheet can also serve as both the catalyst layer and the positive electrode current collector.

[0048] For the current collector of a positive electrode having a positive electrode active material layer or a positive electrode having a catalyst layer, for example, a mesh, foil, expanded metal, or punched metal made of a metal such as titanium, nickel, stainless steel, or copper; a carbon mesh or sheet; or the like can be used.

[0049] A porous carbon sheet can also be used for the positive electrode current collector. Examples of the porous carbon sheet that can be preferably used include nonwoven fabrics made of fibrous carbon, such as carbon paper, carbon cloth, and carbon felt. These sheets may have a single-layer structure, a multilayer structure in which carbon papers, carbon cloths, or carbon felts are laminated together, or a multilayer structure in which two or more of carbon paper, carbon cloth, and carbon felt are laminated together. A porous sheet made of expanded graphite can also be used as the porous carbon sheet.

[0050] The fiber diameter of the fibrous carbon constituting the sheet is preferably 2 to 30 μm, taking into consideration electrical conductivity and the like.

[0051] The thickness of the porous carbon sheet is preferably 500 μm or less from the viewpoint of increasing the energy density of the battery, and the lower limit of the thickness of the porous carbon sheet is usually 50 μm, taking into consideration ease of handling and availability, and ensuring sufficient battery reaction and current collection function at the positive electrode.

[0052] The porosity of the porous carbon sheet is preferably 50% or more, more preferably 70% or more, and is preferably 95% or less, more preferably 85% or less, from the viewpoint of being able to favorably hold the positive electrode active material layer and ensuring sufficient strength.

[0053] The porous carbon sheet may be selected from commercially available products that satisfy the above physical property values.

[0054] When a current collector having pores (voids) is used, the components of the positive electrode active material layer and the components of the catalyst layer may be held in the pores of the current collector, thereby integrating the positive electrode active material layer and the catalyst layer with the current collector.

[0055] The thickness of the positive electrode current collector made of a material other than a porous carbon sheet is preferably 10 μm or more and 300 μm or less.

[0056] When a sheet-like outer casing is used as the outer casing of a battery, a carbon paste can be applied to the surface that will become the inner surface and used as a positive electrode current collector. The thickness of the carbon paste layer is preferably 50 to 200 μm.

[0057] The positive electrode is provided with a terminal for connecting to an external device. As described above, the positive electrode terminal may be formed by attaching a terminal made of a different material to a part of the positive electrode current collector. However, it is preferable to use a part of the sheet constituting the positive electrode current collector as the positive electrode terminal. That is, when cutting the positive electrode current collector, it is possible to form a shape having a main body portion that holds the positive electrode active material layer and the catalyst layer, and a terminal, and to manufacture a positive electrode by holding the positive electrode active material layer and the catalyst layer only on the main body portion.

[0058] The positive electrode terminal can be made of a foil (plate), wire, or porous material made of a metal such as titanium, nickel, stainless steel, or copper, or a conductor such as carbon. Examples of porous materials made of a conductor include expanded metal, punched metal, and aggregates of fibrous conductors. Examples of aggregates of fibrous conductors include the porous carbon sheet mentioned above as an example of a material that can be used for the positive electrode current collector. However, if an aggregate of fibrous conductors is not used for the negative electrode terminal, an aggregate of fibrous conductors is used for the positive electrode terminal.

[0059] The thickness of the positive electrode terminal (the thickness of the portion located inside the exterior body relative to the seal portion after the exterior body is sealed; i.e., the thickness before being compressed by sealing the exterior body) is preferably 50 μm or more, more preferably 120 μm or more, and preferably 500 μm or less, if it is an aggregate of fibrous conductors, and is preferably 20 μm or more and 500 μm or less if it is made of a metal or carbon foil (plate). Furthermore, if the positive electrode terminal is made of a metal or carbon wire, its diameter is preferably 50 μm or more and 1500 μm or less.

[0060] When the positive electrode terminal is an aggregate of fibrous conductors, the thickness of the portion located in the sealed portion is reduced compared to the thickness before sealing and is smaller than the thickness of the portion located inside the exterior body relative to the sealed portion. However, from the viewpoint of better suppressing battery leakage, the thickness (μm) of the portion located in the sealed portion (or the thickness after compression due to sealing of the exterior body; the same applies hereinafter) is preferably 97% or less, and more preferably 95% or less, of the thickness (μm) of the portion located inside the exterior body relative to the sealed portion (or the thickness of the exterior body before sealing; the same applies hereinafter). Furthermore, the thickness (μm) of the portion located in the sealed portion is preferably 70% or more of the thickness (μm) of the portion located inside the exterior body relative to the sealed portion.

[0061] The thicknesses of the positive electrode terminal at each location and the negative electrode terminal at each location described below are values ​​measured by cutting the predetermined locations where the terminals are located and observing the cross section of the cut portion with a digital microscope. In the examples described below, cutting was performed with a ceramic blade using a cell tab cutting jig.

[0062] When the positive electrode terminal is an aggregate of fibrous conductors, the heat-sealing resin is present in at least some of the voids at the location where the seal is located. However, from the viewpoint of better suppressing battery leakage, it is more preferable that the heat-sealing resin is present in the entire voids at the location where the seal is located. The presence of the heat-sealing resin in the voids at the location where the seal is located on the positive electrode terminal can be confirmed by observing the cross section of the location where the seal is located on the positive electrode terminal with a microscope or a scanning electron microscope (SEM) (in the examples described below, confirmation was performed with a microscope).

[0063] <Negative electrode> When the battery is an alkaline battery (primary battery or secondary battery), manganese battery, or air battery, the negative electrode can be one containing, as an active material, at least one metal selected from the group consisting of zinc, aluminum, magnesium, and alloys thereof.

[0064] Specific examples of such negative electrodes that are preferably used include metal sheets made of the above-mentioned materials (zinc foil, zinc alloy foil, magnesium foil, magnesium alloy foil, aluminum foil, and aluminum alloy foil). The thickness of the metal sheet is preferably 5 to 1000 μm.

[0065] Metal particles made of the above materials (zinc particles, zinc alloy particles, magnesium particles, magnesium alloy particles, aluminum particles, aluminum alloy particles) can also be used.

[0066] Examples of alloying components of the zinc alloy include indium, bismuth, and aluminum, and one or more of these elements may be contained.

[0067] The contents of the alloy components in the zinc alloy are, for example, as follows: The indium content is, for example, 0.005% or more and 0.1% or less by mass. The bismuth content is, for example, 0.002% or more and 0.5% or less by mass. The aluminum content is, for example, 0.0001% or more and 0.15% or less by mass.

[0068] Zinc foil and zinc alloy foil include electrolytic foil and rolled foil, but electrolytic foil is preferred because electrolytic foil is less likely to generate gas due to reaction with the electrolyte in the battery, and electrolytic zinc alloy foil containing bismuth is more preferred. The preferred range of bismuth content in the electrolytic zinc alloy foil is 0.02% or more and 0.5% or less by mass.

[0069] Furthermore, examples of alloying components of magnesium alloys include calcium, manganese, zinc, and aluminum, and one or more of these elements may be contained.

[0070] The contents of the alloy components in the magnesium alloy are, for example, as follows: The calcium content is, for example, 1% or more and 3% or less by mass; The manganese content is, for example, 0.1% or more and 0.5% or less by mass; The zinc content is, for example, 0.4% or more and 1% or less by mass; and The aluminum content is, for example, 8% or more and 10% or less by mass.

[0071] Furthermore, examples of alloying components of the aluminum alloy include zinc, tin, gallium, silicon, iron, magnesium, and manganese, and one or more of these elements may be contained.

[0072] The contents of each alloy component in the aluminum alloy are, for example, as follows: The zinc content is, for example, 0.5% or more and 10% or less by mass. The tin content is, for example, 0.04% or more and 1.0% or less by mass. The gallium content is, for example, 0.003% or more and 1.0% or less by mass. The silicon content is, for example, 0.05% or less by mass. The iron content is, for example, 0.1% or less by mass. The magnesium content is, for example, 0.1% or more and 2.0% or less by mass. The manganese content is, for example, 0.01% or more and 0.5% or less by mass.

[0073] In the case of a negative electrode containing metal particles, the metal particles may be of one type alone or two or more types.

[0074] In consideration of reducing the environmental load when discarding batteries, it is preferable that the metal material used for the negative electrode contains small amounts of mercury, cadmium, lead, and chromium, and more preferably the specific contents are, on a mass basis, mercury: 0.1% or less, cadmium: 0.01% or less, lead: 0.1% or less, and chromium: 0.1% or less.

[0075] Regarding the particle size of the zinc particles and zinc alloy particles, for example, the proportion of particles having a particle size of 75 μm or less among all particles is preferably 50 mass% or less, more preferably 30 mass% or less, and the proportion of particles having a particle size of 100 to 200 μm is 50 mass% or more, more preferably 90 mass% or more.

[0076] Regarding the particle size of the magnesium particles, magnesium alloy particles, aluminum particles, and aluminum alloy particles, for example, the proportion of particles having a particle size of 30 μm or less among all particles is preferably 50 mass% or less, more preferably 30 mass% or less, and the proportion of particles having a particle size of 50 to 200 μm is 50 mass% or more, more preferably 90 mass% or more.

[0077] In the case of a negative electrode containing the above-mentioned metal particles, a gelling agent (such as sodium polyacrylate or carboxymethyl cellulose) or a binder may be added as needed to form the mixture, and a negative electrode mixture (such as a gelled negative electrode) can be used by adding an electrolytic solution to this. The amount of gelling agent in the negative electrode is preferably 0.5 to 1.5 mass %, and the amount of binder is preferably 0.5 to 3 mass %.

[0078] The electrolyte for the negative electrode containing metal particles can be the same as that injected into the battery.

[0079] The content of metal particles in the negative electrode is, for example, preferably 60% by mass or more, more preferably 65% ​​by mass or more, and is preferably 95% by mass or less, more preferably 90% by mass or less.

[0080] The negative electrode containing metal particles preferably contains an indium compound, which can more effectively prevent hydrogen gas generation due to a corrosion reaction between the metal particles and the electrolyte.

[0081] Examples of the indium compound include indium oxide and indium hydroxide.

[0082] The amount of the indium compound used in the negative electrode is preferably 0.003 to 1 in terms of mass ratio to 100 metal particles.

[0083] Furthermore, a current collector may be used as needed for the negative electrode containing a metal material. Examples of the current collector for the negative electrode containing a metal material include a mesh, foil, expanded metal, and punched metal made of metal such as nickel, copper, and stainless steel; and a carbon sheet or mesh. Furthermore, the same porous carbon sheet as the specific example of the positive electrode current collector shown above can also be used for the negative electrode current collector.

[0084] The thickness of the negative electrode current collector made of a porous carbon sheet is preferably 50 to 500 μm, and the thickness of the negative electrode current collector made of a material other than a porous carbon sheet is preferably 10 to 300 μm.

[0085] When a sheet-like outer casing is used as the outer casing of a battery, the negative electrode current collector can be used by applying a carbon paste to the surface that is to become the inner surface of the sheet-like outer casing, as in the case of the positive electrode. The thickness of the carbon paste layer is preferably 50 to 200 μm.

[0086] When the battery is a nonaqueous electrolyte battery (primary battery or secondary battery), the negative electrode may have a structure in which a negative electrode mixture layer containing a negative electrode active material and a binder is formed on one or both sides of a current collector, a structure in which a metal foil serving as the negative electrode active material is used as is, or a structure in which a metal foil serving as the negative electrode active material and a current collector are laminated.

[0087] When the battery is a non-aqueous electrolyte primary battery, examples of the negative electrode active material include metallic lithium and lithium alloys (lithium-aluminum alloys).

[0088] When the battery is a non-aqueous electrolyte secondary battery, examples of the negative electrode active material include metallic lithium, lithium alloys (lithium-aluminum alloys), and carbon materials such as graphite, pyrolytic carbons, cokes, glassy carbon, fired bodies of organic polymer compounds, mesophase carbon microbeads, carbon fiber, and activated carbon; alloys containing elements capable of alloying with lithium, such as Si and Sn; and oxides of Si and Sn.

[0089] In the case of a negative electrode having a negative electrode mixture layer, the binder may be the same as the various binders exemplified above as the binder for the positive electrode active material layer. In addition, the negative electrode mixture layer may contain a conductive additive, and in this case, the conductive additive may be the same as the various conductive additives exemplified above as the conductive additive for the positive electrode active material layer.

[0090] In the case of a negative electrode having a negative electrode mixture layer and a current collector, for example, a negative electrode active material and a binder, and further, if necessary, a conductive additive, etc., are dispersed in water or an organic solvent such as NMP to prepare a negative electrode mixture-containing composition (slurry, paste, etc.) (the binder may be dissolved in the solvent), which is then applied to a current collector, dried, and, if necessary, subjected to a pressing treatment such as a calendaring treatment, thereby producing the negative electrode.

[0091] The composition of the negative electrode mixture layer is, for example, preferably such that the content of the negative electrode active material is 70 to 99 mass % and the content of the binder is 1 to 30 mass %. Furthermore, when a conductive additive is used, the content of the conductive additive in the negative electrode mixture layer is preferably 1 to 20 mass %. Furthermore, the thickness of the negative electrode mixture layer is preferably 1 to 100 μm per side of the current collector.

[0092] For the current collector of the negative electrode having the negative electrode mixture layer, for example, a foil made of copper, stainless steel, nickel, titanium, or an alloy thereof can be used, but usually, a copper foil having a thickness of 5 to 30 μm is preferably used.

[0093] The negative electrode terminal can be a foil (plate), wire, or porous body made of a conductor such as a metal, such as copper, stainless steel, nickel, titanium, or an alloy thereof, or carbon. Examples of porous bodies made of a conductor include expanded metal, punched metal, and aggregates of fibrous conductors. Examples of aggregates of fibrous conductors include the porous carbon sheet mentioned above as an example of a material that can be used for the positive electrode current collector. However, if an aggregate of fibrous conductors is not used for the positive electrode terminal, an aggregate of fibrous conductors is used for the negative electrode terminal.

[0094] The negative electrode terminal can also be formed by providing a portion of the negative electrode current collector where the negative electrode mixture layer is not provided. Furthermore, when the negative electrode is made of a metal sheet, the metal sheet can be cut into a shape having a main body that functions as the negative electrode active material and a terminal, thereby forming a negative electrode having a main body and a terminal from a single metal sheet.

[0095] The thickness of the negative electrode terminal (the thickness of the portion located inside the exterior packaging body relative to the seal portion after the exterior packaging body has been sealed; i.e., the thickness before being compressed by sealing the exterior packaging body) is preferably 50 μm or more, more preferably 120 μm or more, and preferably 500 μm or less, if it is an aggregate of fibrous conductors, and is preferably 20 μm or more and 500 μm or less if it is made of a metal or carbon foil (plate). Furthermore, if the negative electrode terminal is made of a metal or carbon wire, its diameter is preferably 50 μm or more and 1500 μm or less.

[0096] When the negative electrode terminal is an aggregate of fibrous conductors, the thickness of the portion located in the sealed portion is reduced compared to the thickness before sealing and is smaller than the thickness of the portion located inside the exterior body relative to the sealed portion. However, from the viewpoint of better suppressing battery leakage, the thickness (μm) of the portion located in the sealed portion (or the thickness after compression by sealing the exterior body; the same applies hereinafter) is preferably 97% or less, and more preferably 95% or less, of the thickness (μm) of the portion located inside the exterior body relative to the sealed portion (or the thickness of the exterior body before sealing; the same applies hereinafter). Furthermore, the thickness (μm) of the portion located in the sealed portion is preferably 70% or more of the thickness (μm) of the portion located inside the exterior body relative to the sealed portion.

[0097] When the negative electrode terminal is an aggregate of fibrous conductors, the heat-sealing resin is present in at least some of the voids at the location where the seal portion is located. However, from the viewpoint of better suppressing battery leakage, it is more preferable that the heat-sealing resin is present in the entire voids at the location where the seal portion is located. The presence of the heat-sealing resin in the voids at the location where the seal portion of the negative electrode terminal is located can be confirmed by observing a cross section of the location where the seal portion of the negative electrode terminal is located using a microscope or SEM.

[0098] <Separator> In a battery, a separator is interposed between the positive electrode and the negative electrode. When the battery is an alkaline battery, a manganese battery, or an air battery, the separator can be made of a nonwoven fabric mainly composed of vinylon and rayon, a vinylon-rayon nonwoven fabric (vinylon-rayon mixed paper), a polyamide nonwoven fabric, a polyolefin-rayon nonwoven fabric, vinylon paper, vinylon-linter pulp paper, or vinylon-mercerized pulp paper. Microporous films can also be used, specifically microporous polyolefin films (such as microporous polyethylene films and microporous polypropylene films), and their surfaces may be hydrophilized to improve wettability with aqueous electrolytes (aqueous electrolyte solutions). Furthermore, the separator can be made by stacking the microporous film, a cellophane film, and a liquid-absorbing layer (electrolyte retention layer) such as vinylon-rayon mixed paper.

[0099] When the battery is a non-aqueous electrolyte battery, the separator may be a microporous polyolefin film (such as a microporous polyethylene film or a microporous polypropylene film).

[0100] The thickness of the separator is preferably, for example, 10 to 500 μm, and in the case of a microporous film, it is preferably 10 to 50 μm, and in the case of a nonwoven fabric, it is preferably 20 to 500 μm.

[0101] <Electrolyte> When the battery is an alkaline battery, an alkaline electrolyte is used as the electrolyte. Examples of alkaline electrolytes that can be used include an alkaline aqueous solution of an alkali metal hydroxide such as potassium hydroxide, sodium hydroxide, or lithium hydroxide, and an alkaline electrolyte to which zinc oxide has been added. The concentration of the alkali metal hydroxide in the alkaline electrolyte is preferably 28 to 38 mass % in the case of potassium hydroxide, for example, and if zinc oxide is used, the concentration is preferably 1.0 to 4.0 mass %.

[0102] When the battery is a manganese battery or an air battery, examples of the electrolyte salts to be dissolved in the aqueous solution used as the electrolyte include chlorides such as sodium chloride, potassium chloride, magnesium chloride, calcium chloride, ammonium chloride, and zinc chloride; hydroxides of alkali metals and alkaline earth metals (sodium hydroxide, potassium hydroxide, magnesium hydroxide, etc.), acetates (sodium acetate, potassium acetate, magnesium acetate, etc.), nitrates (sodium nitrate, potassium nitrate, magnesium nitrate, etc.), sulfates (sodium sulfate, potassium sulfate, magnesium sulfate, etc.), phosphates (sodium phosphate, potassium phosphate, lithium phosphate, etc.), and the like. Examples of suitable electrolyte salts include sodium phosphate, magnesium phosphate, borates (sodium borate, potassium borate, magnesium borate, etc.), citrates (sodium citrate, potassium citrate, magnesium citrate, etc.), glutamates (sodium glutamate, potassium glutamate, magnesium glutamate, etc.); alkali metal bicarbonates (sodium bicarbonate, potassium bicarbonate, etc.); alkali metal percarbonates (sodium percarbonate, potassium percarbonate, etc.); halogen-containing compounds such as fluorides; and polycarboxylic acids. The electrolyte may contain one or more of these electrolyte salts. Among these, it is preferable to use an aqueous solution of zinc chloride as the electrolyte, and the concentration of zinc chloride is preferably 10 to 40% by mass.

[0103] Furthermore, when a metal sheet such as zinc foil or zinc alloy foil is used for the negative electrode, corrosion from the aqueous electrolyte can cause the negative electrode to break, leading to problems such as insufficient capacity. However, by incorporating a thickener into the aqueous electrolyte, preferably in a gel form (gel electrolyte), such problems can be prevented. Examples of thickeners that can be incorporated into the electrolyte include cellulose derivatives such as carboxymethyl cellulose (CMC) and carboxyethyl cellulose (CEC); polyalkylene glycols such as polyethylene glycol (PEG) (preferably with a molecular weight of 1,000 or more, more preferably 10,000 or more); polyvinylpyrrolidone; polyvinyl acetate; starch; guar gum; xanthan gum; sodium alginate; hyaluronic acid; gelatin; polyacrylic acid; and various other synthetic or natural polymers. Furthermore, when using thickeners among the above examples that contain a functional group (such as -COOH or -COONa) consisting of a carboxyl group or a salt thereof in the molecule, it is also preferable to incorporate a polyvalent metal salt that acts as a gelation promoter into the electrolyte. The blending amount of the thickener in the electrolyte is preferably 0.1 to 5% by mass. When a gelation accelerator is used, the ratio of the gelation accelerator is preferably 1 to 30% by mass when the ratio of the thickener is 100% by mass.

[0104] When the battery is a non-aqueous electrolyte battery, a solution (non-aqueous electrolyte) in which a lithium salt is dissolved in a non-aqueous solvent is used as the electrolyte. In this case, the lithium salt is LiClO ４ , LiPF ６ , LiBF ４ , LiAsF ６ , LiSbF ６ Inorganic lithium salts such as LiCF ３ SO ３ , LiCF ３ CO ２ , Li ２ C ２ F ４ (SO ３ ) ２ , LiN(CF ３ SO ２ ) ２ , LiC(CF ３SO ２ ) ３ , LiC ｎ F ２ｎ＋１ SO ３ (n≧2), LiN(R ｆ OSO ２ ) ２ [Here, R ｆ is a fluoroalkyl group]; and the like.

[0105] In addition, non-aqueous solvents for non-aqueous electrolytes include cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, and vinylene carbonate; chain carbonates such as dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate; chain esters such as methyl propionate; cyclic esters such as γ-butyrolactone; chain ethers such as dimethoxyethane, diethyl ether, 1,3-dioxolane, diglyme, triglyme, and tetraglyme; cyclic ethers such as dioxane, tetrahydrofuran, and 2-methyltetrahydrofuran; nitriles such as acetonitrile, propionitrile, and methoxypropionitrile; sulfites such as ethylene glycol sulfite; and the like. These may be used alone or in combination of two or more. In order to obtain a battery with better characteristics, it is desirable to use a combination that can obtain high conductivity, such as a mixed solvent of ethylene carbonate and a chain carbonate. Furthermore, for the purpose of improving properties such as safety, charge / discharge cycle properties, and high-temperature storage properties, additives such as vinylene carbonates, 1,3-propane sultone, diphenyl disulfide, cyclohexylbenzene, biphenyl, fluorobenzene, and t-butylbenzene may be added to these nonaqueous electrolyte solutions as appropriate.

[0106] The concentration of the lithium salt in the non-aqueous electrolyte is preferably 0.5 to 1.5 mol / L, and more preferably 0.9 to 1.25 mol / L.

[0107] The aqueous electrolyte solution or the non-aqueous electrolyte solution may be made into a gel (gel electrolyte) by using a gelling agent such as a known polymer.

[0108] <Battery Shape, etc.> There are no particular limitations on the shape of the battery, as long as it has an exterior body with a sealed structure formed by a seal part that utilizes fusion of a heat-sealable resin. However, if the battery is a sheet-like battery having a sheet-like exterior body made of a resin film, it can be used well as a power source for medical and health-related devices, such as patches that can be worn on the body, particularly patches that are worn on the surface of the skin to measure body conditions such as body temperature, pulse rate, and sweat rate.

[0109] The sheet-like outer packaging body is made of a resin film, and examples of such a resin film include nylon film (such as nylon 66 film) and polyester film (such as polyethylene terephthalate (PET) film).

[0110] The sheet-like outer packaging is typically sealed by heat-sealing the edges of the upper and lower resin films of the sheet-like outer packaging. A heat-sealing resin is used to facilitate this heat-sealing process. In this case, a heat-sealing resin layer is laminated onto the resin film exemplified above and used for the sheet-like outer packaging. Examples of heat-sealing resins that make up the heat-sealing resin layer include modified polyolefins (e.g., modified polyolefin ionomers), polyethylene and its copolymers, and polypropylene and its copolymers. The heat-sealing resin layer may be formed on the entire surface of one side of the resin film that makes up the sheet-like outer packaging, or may be formed only in the area intended to become the sealing portion. The thickness of the heat-sealing resin layer is preferably 20 to 200 μm.

[0111] A metal layer may be laminated on the resin film. The metal layer may be made of an aluminum film (aluminum foil, including aluminum alloy foil), a stainless steel film (stainless steel foil), or the like. The thickness of the metal layer is preferably 10 to 150 μm.

[0112] Furthermore, the resin film constituting the sheet-like outer packaging body may be a film having a configuration in which the above-mentioned heat-sealable resin layer and the above-mentioned metal layer are laminated together.

[0113] It is also preferable that the resin film constituting the sheet-like exterior body has an electrically insulating water vapor barrier layer. In this case, the electrically insulating resin film may have a single-layer structure in which it itself also serves as a water vapor barrier layer, or a multilayer structure in which it has multiple electrically insulating resin film layers, at least one of which serves as a water vapor barrier layer, or a multilayer structure in which an electrically insulating water vapor barrier layer is provided on the surface of a base layer made of a resin film.

[0114] Among such resin films, those in which a water vapor barrier layer made of at least an inorganic oxide is formed on the surface of a base layer made of a resin film are preferably used.

[0115] Examples of inorganic oxides constituting the water vapor barrier layer include aluminum oxide and silicon oxide. Note that a water vapor barrier layer made of silicon oxide tends to have a higher function of suppressing the permeation of moisture in the electrolyte solution in the battery than a water vapor barrier layer made of aluminum oxide. Therefore, it is more preferable to use silicon oxide as the inorganic oxide constituting the water vapor barrier layer.

[0116] The water vapor barrier layer made of an inorganic oxide can be formed on the surface of the substrate layer by, for example, a vapor deposition method. The thickness of the water vapor barrier layer is preferably 10 to 300 nm.

[0117] Examples of the substrate layer of the resin film having a water vapor barrier layer include the above-mentioned nylon film and polyester film, as well as polyolefin film, polyimide film, polycarbonate film, etc. The thickness of the substrate layer is preferably 5 to 100 μm.

[0118] In the case of a resin film having a water vapor barrier layer and a substrate layer, a protective layer for protecting the water vapor barrier layer may be formed on the surface of the water vapor barrier layer (the surface opposite to the substrate layer).

[0119] Furthermore, in the case of a resin film having a water vapor barrier layer and a substrate layer, the above-mentioned heat-sealable resin layer may be further laminated thereon.

[0120] The overall thickness of the resin film is preferably 10 μm or more from the viewpoint of providing sufficient strength to the battery, and is preferably 200 μm or less from the viewpoint of preventing an increase in the battery thickness and a decrease in energy density.

[0121] The water vapor permeability of the resin film constituting the sheet-like outer packaging body is 10 g / m ２ It is preferable that the resin film does not transmit water vapor as much as possible, that is, the water vapor transmission rate is preferably as low as possible, and is preferably 0 g / m ２ ・It may be 24 hours.

[0122] The water vapor permeability of the resin film referred to in this specification is a value measured in accordance with Japanese Industrial Standards (JIS) K 7129 (2008).

[0123] In addition, when the battery is an air battery, it is preferable that the resin film constituting the sheet-like outer casing has a certain degree of oxygen permeability. Air batteries discharge by supplying air (oxygen) to the positive electrode, so air holes for introducing oxygen into the battery are formed in the sheet-like outer casing. However, if the resin film constituting the sheet-like outer casing has oxygen permeability, oxygen can be introduced into the battery through the outer casing from locations other than the air holes in the sheet-like outer casing. This allows oxygen to be supplied more uniformly throughout the positive electrode, improving the battery's discharge characteristics and extending its discharge time. It is also possible to realize a sheet-like air battery that does not have air holes in the sheet-like outer casing.

[0124] When the battery is an air battery, the specific oxygen permeability of the resin film constituting the sheet-like outer casing is 0.02 cm ３ / m ２ ・24h ・MPa or more is preferable, 0.2 cm ３ / m ２ However, if the battery is an air battery, if the resin film constituting the sheet-like outer casing is permeable to too much oxygen, self-discharge may occur and the capacity may be lost. Therefore, the oxygen permeability of the resin film is set to 100 cm３ / m ２ ・24h ・MPa or less is preferable, 50 cm ３ / m ２ It is more preferable that the pressure is 24h·MPa or less.

[0125] On the other hand, when the battery is a battery other than an air battery, there is no particular restriction on the oxygen permeability of the resin film constituting the sheet-like outer casing. However, from the viewpoint of improving the storage stability of the battery, it is preferable that the resin film does not allow much oxygen to permeate. The oxygen permeability of the specific resin film is 10 cm ３ / m ２ It is preferable that the pressure is 24h·MPa or less.

[0126] The oxygen permeability of the resin film referred to in this specification is a value measured in accordance with JIS K 7126-2 method.

[0127] When the battery is an air battery, a water-repellent film is usually disposed between the positive electrode and the exterior body. The water-repellent film is a film that is water-repellent but air-permeable. Specific examples of such water-repellent films include films made of resins such as fluororesins such as PTFE; and polyolefins such as polypropylene and polyethylene. The thickness of the water-repellent film is preferably 50 to 250 μm.

[0128] Furthermore, when the battery is an air battery, an air diffusion membrane may be disposed between the exterior body and the water-repellent film to supply air taken into the exterior body to the positive electrode. The air diffusion membrane may be a nonwoven fabric made of a resin such as cellulose, polyvinyl alcohol, polypropylene, or nylon. The thickness of the air diffusion membrane is preferably 100 to 250 μm.

[0129] When the battery is a sheet-type battery, there is no particular limitation on its thickness (the length of a in FIG. 2 ), and it can be changed appropriately depending on the application of the battery. One of the advantages of a sheet-type battery is that it can be made thin, and from this perspective, it is preferable that the thickness is, for example, 1 mm or less. When the battery is a sheet-type air battery, it is particularly easy to provide such a thin battery.

[0130] There is no particular lower limit to the thickness of the sheet-type battery, but it is usually preferable to set it to 0.2 mm or more in order to ensure a certain capacity.

[0131] When the positive electrode terminal and / or the negative electrode terminal are an aggregate of fibrous conductors, the thickness can be reduced from that before sealing, and the thickness of the portion located at the sealed portion of the outer casing can be made smaller than the thickness of the portion located inside the sealed portion of the outer casing by adjusting the pressure conditions and temperature conditions when heat-sealing the outer casing.

[0132] By heat-sealing the positive electrode terminal and / or negative electrode terminal so that the thickness of the portion located in the seal portion of the exterior body is reduced from the thickness before sealing and is smaller than the thickness of the portion located inside the exterior body relative to the seal portion, the seal portion is formed with the heat-sealing resin of the seal portion penetrating into the voids at the portion of the positive electrode terminal and / or negative electrode terminal composed of an aggregate of fibrous conductors where the seal portion is located. Therefore, the heat-sealing resin is present in the voids at the portion of the seal portion of the positive electrode terminal and / or negative electrode terminal, which allows the peel strength of the seal portion of the exterior body (the seal portion where the positive electrode terminal and negative electrode terminal composed of an aggregate of fibrous conductors are located) to be increased to 3.0 N / 3 mm or more (even 5.0 N / 3 mm or more), thereby improving the sealing performance of the seal portion. The upper limit of the peel strength of the seal portion is not particularly limited, but is typically about 8 N / 3 mm.

[0133] FIG. 4 shows a diagram illustrating a sample for measuring the peel strength of the seal portion. Here, a sample including a positive electrode terminal composed of an aggregate of fibrous conductors is described. FIG. 4 is a plan view of a battery 10. The sample 100 for measuring the peel strength of the seal portion is formed by cutting the battery 10 at the dotted line shown in the figure, from the upper end of the positive electrode terminal 23 to the lower end of the exterior body 50. The width of the sample 100 (the horizontal length in the figure) is 3 mm. When the negative electrode terminal is composed of an aggregate of fibrous conductors, the sample for measuring the peel strength of the seal portion is also prepared in the same manner as for the positive electrode terminal.

[0134] The peel strength of the seal portion referred to in this specification is a value determined as follows. The battery 10 is cut along the dotted line in FIG. 4 to prepare the sample 100. Using a tensile tester with two jigs, one above the other, that sandwich the measurement sample, the two films constituting the exterior body of the sample 100 are opened at the lower holding position 100a in the figure. One of the films is sandwiched between the lower jig of the tensile tester at the holding position 100a, and the other is sandwiched between the upper jig of the tensile tester at the holding position 100a. Then, with the lower jig fixed, the upper jig is moved upward at a speed of 1 cm / sec, pulling the two films constituting the exterior body of the sample 100 in the opening direction. The maximum force required to peel the terminal and the exterior body (film) at the seal portion 100b of the sample 100 at this time is defined as the peel strength of the seal portion.

[0135] The present invention will be described in detail below based on examples, but the present invention is not limited to these examples.

[0136] Example 1 <Positive electrode> DBP oil absorption amount 495 cm ３ / 100g, specific surface area 1270m ２ A catalyst layer-forming composition was prepared by mixing 10 parts by mass of carbon (Ketjenblack EC600JD (Lion Specialty Chemicals)) with a molecular weight of 1.0 g / g, 1.0 part by mass of a phthalocyanine air catalyst, 2.5 parts by mass of an acrylic dispersant, 7.5 parts by mass of polytetrafluoroethylene, and 500 parts by mass of ethanol.

[0137] A porous carbon paper (thickness: 0.25 mm, porosity: 75%) was used as a current collector, and the catalyst layer-forming composition was applied in an amount of 10 mg / cm after drying. ２ The resulting solution was applied in stripes to the surface of the substrate so that the thickness of the stripe was 15 mm, and then dried to obtain a current collector having a portion where the catalyst layer was formed and a portion where the catalyst layer was not formed. This current collector was then punched out to have a shape with a catalyst layer size of 15 mm x 15 mm and a terminal portion with a size of 8 mm x 15 mm where the catalyst layer was not formed at one end, thereby producing a positive electrode (air electrode) with an overall thickness of 0.27 mm.

[0138] <Negative Electrode> A zinc alloy foil (thickness: 0.05 mm, electrolytic zinc foil) containing 0.05% In, 0.07% Bi, and 0.001% Al as additive elements was punched out into a shape having a 15 mm × 15 mm portion that would function as an active material and a 5 mm × 15 mm portion at one end that would serve as a terminal, to prepare a negative electrode.

[0139] <Electrolyte> An electrolyte solution (pH measured at 25°C using a HORIBA, Ltd. "LAQUA Twin Compact pH Meter" at 25°C was 4.3, and the pH values ​​measured using the same method for the electrolyte solutions of the sheet-type air batteries of all Examples and Comparative Examples described below) was prepared by adding glycerin to a 25% by mass aqueous solution of ammonium chloride in an amount that was 10% by mass relative to the total amount of water. The concentrations of perchlorate ions and heavy metal ions excluding iron ions in the electrolyte solution were each less than 100 ppm. The same was true for the electrolyte solutions of the sheet-type air batteries of all Examples and Comparative Examples described below.

[0140] <Separator> The separator used was a single graft film (thickness: 25 μm) made of a graft copolymer having a structure in which acrylic acid was graft copolymerized onto a polyethylene main chain, with nonwoven fabrics (thickness: 100 μm) placed on both sides (total thickness: 225 μm).

[0141] <Water-repellent film> A microporous film made of polyethylene and having a thickness of 50 μm was used as the water-repellent film.

[0142] <Assembly of Battery> Two laminate films (total thickness 132 μm) measuring 25 mm × 30 mm each having a base layer having a silica vapor deposition layer or the like on one side of a PET film and a heat-sealable resin layer having a thickness of 100 μm were prepared and used as exterior bodies.

[0143] One of the laminate films for the exterior body, which was placed on the positive electrode side, had five air holes with a diameter of approximately 0.1 mm arranged like the 5s on a die, with the air holes at the four corners spaced 9.3 mm vertically and 9.3 mm horizontally (the center-to-center distance between the air holes was 9.4 mm), and the air holes at the center were formed at equal intervals inward from the air holes at the four corners.

[0144] The water-repellent film, the positive electrode, the separator, and the negative electrode were stacked in this order with the sheet-like outer casing facing downwards, and then another outer casing was placed on top of it. Next, the three peripheral edges of the two outer casings were heat-sealed to form a bag, and the electrolyte was poured into the opening, which was then heat-sealed to seal the opening, completing a sheet-like air battery. The heat sealing of the seal portion of the outer casing was performed at a temperature of 225°C and a pressure of 0.3 MPa for 2 seconds.

[0145] A number of sheet-like air batteries were fabricated in this way, and the thickness of the positive electrode terminal of some of them was examined. The thickness a at the seal portion of the exterior body was 169 μm, and the thickness b at the portion located inside the exterior body from the seal portion was 192 μm, with the ratio of thickness a to thickness b being 88%. Furthermore, when the cross section of the positive electrode terminal at the seal portion of the exterior body was observed with a microscope, it was confirmed that a heat-sealing resin was present in the gap.

[0146] Example 2 A plurality of sheet-shaped air batteries were produced in the same manner as in Example 1, except that the conditions for heat sealing of the seal portion of the exterior body were changed to a temperature of 225° C. and a pressure of 0.3 MPa for 1 second.

[0147] When the thickness of the positive electrode terminal of some of the obtained batteries was examined, it was found that the thickness a at the portion located in the sealed portion of the exterior body was 199 μm, and the thickness b at the portion located inside the sealed portion of the exterior body was 205 μm, with the ratio of thickness a to thickness b being 97%. Furthermore, when the cross section of the positive electrode terminal at the portion located in the sealed portion of the exterior body was observed with a microscope, it was confirmed that a heat-sealing resin was present in the gap.

[0148] Example 3 A plurality of sheet-shaped air batteries were produced in the same manner as in Example 1, except that the conditions for heat sealing of the seal portion of the exterior body were changed to a temperature of 225° C. and a pressure of 0.3 MPa for 4 seconds.

[0149] When the thickness of the positive electrode terminal of some of the obtained batteries was examined, it was found that the thickness a at the portion located in the sealed portion of the exterior body was 164 μm, and the thickness b at the portion located inside the sealed portion of the exterior body was 195 μm, with the ratio of thickness a to thickness b being 84%. Furthermore, when the cross section of the positive electrode terminal at the portion located in the sealed portion of the exterior body was observed with a microscope, it was confirmed that a heat-sealing resin was present in the gap.

[0150] Comparative Example 1 A plurality of sheet-like air batteries were produced in the same manner as in Example 1, except that the laminate film used for the exterior body was changed to one having a base layer having a silica vapor deposition layer or the like on one side of a PET film and a heat-sealable resin layer having a thickness of 60 μm, for a total thickness of 92 μm.

[0151] When the thickness of the positive electrode terminal of some of the obtained batteries was examined, it was found that the thickness a at the portion located in the seal portion of the outer casing was 212 μm, and the thickness b at the portion located inside the seal portion of the outer casing was 209 μm, and the ratio of thickness a to thickness b was 101%.

[0152] Comparative Example 2 A plurality of sheet-shaped air batteries were produced in the same manner as in Comparative Example 1, except that the conditions for heat sealing of the seal portion of the exterior body were changed to a temperature of 225° C. and a pressure of 0.3 MPa for 4 seconds.

[0153] The thickness of the positive electrode terminal of some of the obtained batteries was examined, and it was found that the thickness a at the portion located in the seal portion of the outer casing was 210 μm, and the thickness b at the portion located inside the seal portion of the outer casing was 201 μm, and the ratio of thickness a to thickness b was 104%.

[0154] <Leakage Confirmation Test> Five sheet-type air batteries of each of the Examples and Comparative Examples were prepared, and a 5 kg weight was placed on each of these sheet-type air batteries. They were then left in an environment of 25°C for 30 days to check for leakage, and the number of batteries that leaked was used for evaluation.

[0155] The evaluation results are shown in Table 1 together with the configuration of the positive electrode terminal (thickness a of the portion located in the seal portion of the exterior body, thickness b of the portion located further inside the exterior body, and the ratio (%) of thickness a to thickness b), and the peel strength of the seal portion determined by the method described above. In Table 1, the ratio (%) of thickness a to thickness b is represented as "a / b."

[0156]

[0157] As shown in Table 1, the batteries of Examples 1 to 3, in which the thickness a of the portion of the positive electrode terminal formed from an aggregate of fibrous conductors was smaller than the thickness b of the portion of the positive electrode terminal located inside the seal portion of the exterior body, did not exhibit leakage and exhibited excellent leakage resistance.

[0158] In contrast, in the batteries of Comparative Examples 1 and 2 in which the thickness a was greater than the thickness b, leakage was observed in most of the evaluated batteries.

[0159] The leakage confirmation test conducted on the batteries of Examples 1 and 2 and Comparative Examples 1 and 2 was conducted under the condition of increasing the internal pressure by placing a 5 kg weight on the battery, as described above, but no leakage occurred even under such harsh conditions in the batteries of Examples 1 and 2. On the other hand, the batteries of Comparative Examples 1 and 2 leaked in the leakage confirmation test, but no leakage was observed under normal battery usage conditions (for example, when a 0.5 kg weight was placed on the battery).

[0160] The present invention can be implemented in other forms without departing from the spirit of the present invention. The embodiments disclosed in this application are merely examples, and the present invention is not limited to these embodiments. The scope of the present invention shall be interpreted in accordance with the appended claims rather than the description in the above specification, and all modifications within the scope of the claims are included in the scope of the claims.

[0161] The battery of the present invention can be used in the same applications as those in which various known primary and secondary batteries are used.

[0162] REFERENCE SIGNS LIST 10 Battery 20 Positive electrode 21 Positive electrode active material layer 22 Positive electrode current collector 23 Positive electrode terminal 30 Negative electrode 33 Negative electrode terminal 40 Separator 50 Sheet-like outer casing 51 Sealing portion 52 Heat-sealable resin layer 100 Peel strength measurement sample

Claims

1. A battery in which a positive electrode, a negative electrode, a separator, and an electrolyte are sealed in a sheet-like exterior body, wherein the exterior body has a heat-sealable resin layer formed on the inside and a seal part fused by the heat-sealable resin of the heat-sealable resin layer, the positive electrode and the negative electrode have terminals that lead from the inside of the exterior body to the outside via the seal part, and at least one of the positive electrode terminal and the negative electrode terminal is made of an aggregate of fibrous conductors, and the thickness of the part located at the seal part is smaller than the thickness of the part located inside the exterior body beyond the seal part.

2. The battery according to claim 1, wherein the peel strength of the seal portion of the exterior body is 3.0 N / 3 mm or more.

3. The battery according to claim 1, wherein the thickness of the terminal at the seal portion is 97% or less of the thickness of the terminal at the portion located inside the exterior body relative to the seal portion.

4. The battery according to claim 1, wherein the thickness of the heat-sealable resin layer of the exterior body is 150 μm or less.

5. The battery according to claim 1, wherein the thickness of the terminal at a portion located inside the exterior body relative to the seal portion is 120 μm or more.

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