Button alkaline battery

Abstract

The present invention provides an alkaline button cell that has excellent load characteristics and high reliability.　An alkaline button cell which is obtained by having a positive electrode that has a positive electrode mixture layer containing silver oxide and a conductive assistant, a negative electrode that contains zinc particles, and an alkaline electrolyte solution contained in a battery container that is composed of an outer package can, a cover plate and a resin gasket, wherein: carbon black and graphite particles are contained as the conductive assistant in the positive electrode mixture layer; and the water content in the battery container is set to 0.63-1 g per 1 g of the zinc particles in the negative electrode.

Description

[Technical field]

[0001] The present invention relates to a button-type alkaline battery which has excellent load characteristics and high reliability. [Background technology]

[0002] 2. Description of the Related Art Alkaline batteries (silver oxide batteries) having a positive electrode containing silver oxide and an alkaline electrolyte are widely used as primary batteries.

[0003] Various studies have been conducted to improve the characteristics of this type of battery. For example, Patent Document 1 discloses a flat silver oxide battery in which the amount of water in the battery system is set to 0.42 to 0.55 g per 1 g of zinc particles or zinc alloy particles in the negative electrode in order to make the discharge reaction proceed more smoothly and improve the load characteristics.

[0004] Patent Document 2 also describes a method for improving the load characteristics of a battery by increasing the conductivity in the positive electrode mixture without impairing the capacity of the battery, by setting the content of a conductive assistant in the positive electrode mixture to 3 to 7 mass % and setting the density of a molded body of the positive electrode mixture to 5.0 to 7.0 g / cm. 3 A flat silver oxide battery is disclosed.

[0005] In the flat silver oxide battery described in Patent Documents 1 and 2, the internal resistance of the battery is reduced, and therefore the load characteristics can be improved to a certain extent. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2010-218711 A [Patent Document 2] JP 2010-218710 A Summary of the Invention [Problem to be solved by the invention]

[0007] On the other hand, in medical applications and the like, there is a demand for even higher output from batteries, and the development of button-type alkaline batteries that can meet this demand is also underway. For example, attempts have been made to further increase the amount of electrolyte and to further increase the content of conductive additives in the positive electrode mixture.

[0008] However, if the amount of water in the battery is increased beyond the range described in Patent Document 1, leakage of the electrolyte is likely to occur. In particular, when the amount of zinc particles filled inside the sealing plate is increased during assembly of the battery to reduce voids in the battery container in order to increase the discharge capacity, the leakage problem is more likely to occur.

[0009] Furthermore, even if the content of the conductive additive in the positive electrode mixture, such as graphite, is increased beyond the range described in Patent Document 2, it is not necessarily possible to improve the load characteristics. Instead, the load characteristics decrease as the proportion of the positive electrode active material decreases. For this reason, further investigation is required to realize high output of the battery.

[0010] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a button-type alkaline battery which has excellent load characteristics and high reliability. [Means for solving the problem]

[0011] The button-type alkaline battery of the present invention comprises a positive electrode having a positive electrode mixture layer containing silver oxide and a conductive assistant, a negative electrode containing zinc particles, and an alkaline electrolyte housed in a battery container formed of an outer can, a sealing plate, and a resin gasket, the positive electrode mixture layer containing carbon black and graphite particles as the conductive assistant, and the amount of water in the battery container is 0.63 to 1 g per 1 g of zinc particles in the negative electrode. Effect of the Invention

[0012] According to the present invention, it is possible to provide a button-type alkaline battery that has excellent load characteristics and high reliability. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a longitudinal sectional view illustrating a schematic diagram of an example of a button alkaline battery of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] FIG. 1 is a longitudinal cross-sectional view showing a schematic example of a button alkaline battery of the present invention. In the button alkaline battery 1 shown in FIG. 1, a sealing plate 3 containing a negative electrode 5 is fitted into the opening of an outer can 2 containing a positive electrode 4 and a separator 6 via a ring-shaped resin gasket 7 having an L-shaped cross section, and the open end of the outer can 2 is tightened inward, so that the resin gasket 7 abuts against the sealing plate 3, sealing the opening of the outer can 2 and forming a sealed structure inside the battery. That is, in the button alkaline battery 1 shown in FIG. 1, power generating elements including a positive electrode 4, a negative electrode 5, and a separator 6 are loaded into the space (sealed space) in the battery container consisting of the outer can 2, the sealing plate 3, and the resin gasket 7, and further an alkaline electrolyte (not shown) is contained. The outer can 2 also serves as a positive electrode terminal, and the sealing plate 3 also serves as a negative electrode terminal.

[0015] In the button alkaline battery 1 shown in FIG. 1, the peripheral edge of the positive electrode 4 is disposed between the inner bottom surface of the exterior can 2 and the bottom surface of the gasket 7.

[0016] The configuration of the button alkaline battery of the present invention will be described in detail below.

[0017] <Negative electrode> The negative electrode according to the present invention contains zinc particles, and the zinc in the particles acts as an active material. In order to suppress hydrogen gas generation from the negative electrode in the battery, it is desirable for the zinc particles to contain one or more elements such as indium, bismuth, aluminum, and magnesium.

[0018] The content of the above elements in the zinc particles is preferably 0.03 mass % or more for indium, 0.02 mass % or more for bismuth, 0.0005 mass % or more for aluminum, and 0.0002 mass % or more for magnesium.

[0019] On the other hand, if the content of the above elements in the zinc particles is too high, problems such as a deterioration in the battery discharge characteristics and an increase in the amount of hydrogen gas generated are likely to occur, so the content of each element is preferably 0.07 mass% or less for indium, preferably 0.06 mass% or less for bismuth, preferably 0.01 mass% or less for aluminum, and preferably 0.003 mass% or less for magnesium.

[0020] From the viewpoint of environmental load, the zinc particles used are generally those that do not contain harmful elements such as mercury and lead.

[0021] Regarding the particle size of the zinc particles, for example, the ratio of particles having a particle size of 75 μm or less in the whole powder is preferably 25 mass% or less, more preferably 20 mass% or less, and particularly preferably 10 mass% or less. Also, the ratio of particles having a particle size of more than 75 μm and 150 μm or less is preferably 50 mass% or more, more preferably 70 mass% or more, and particularly preferably 90 mass% or more.

[0022] The particle size of zinc particles can be determined based on the percentage of particles that pass through a sieve with 75 μm openings (200 mesh sieve), the percentage of particles that do not pass through a 75 μm sieve but pass through a 150 μm sieve (100 mesh sieve), and the percentage of particles that do not pass through a 150 μm sieve (the sum of these percentages equals 100% by mass).

[0023] The negative electrode is formed using a mixture of the zinc particles and an alkaline electrolyte, and the mixture for the negative electrode may further contain a gelling agent such as sodium polyacrylate or carboxymethyl cellulose, if necessary.

[0024] <Water content in battery container> In the button alkaline battery of the present invention, from the viewpoint of reducing the factors inhibiting the battery reaction, reducing the internal resistance of the battery, and improving the load characteristics, the composition of the electrolyte and the amount of electrolyte are adjusted so that the amount of water in the battery container, i.e., the mass of water contained in the total electrolyte in the battery system, including the electrolyte contained in the components such as the negative electrode, positive electrode, and separator, is 0.63 g or more per 1 g of zinc particles in the negative electrode. To further improve the load characteristics, the amount of water in the battery container is preferably 0.7 g or more, more preferably 0.8 g or more, per 1 g of zinc particles in the negative electrode.

[0025] On the other hand, if the amount of moisture in the battery container is too high, the battery is more likely to leak during storage. In addition, when the electrolyte is poured into the container or when the container is sealed during battery assembly, the electrolyte may overflow outside the container, resulting in assembly defects. Therefore, the amount of moisture in the battery container must be kept to 1 g or less per 1 g of zinc particles in the negative electrode, preferably 0.95 g or less, and more preferably 0.9 g or less.

[0026] Here, when the amount of moisture held by components such as the positive electrode active material, the negative electrode active material, the binder, the separator, for example, the amount of adsorbed moisture, is negligible, the amount of moisture in the electrolyte used to assemble the battery may be used as the amount of moisture in the battery container.

[0027] In addition, when determining the amount of moisture in the battery container after the battery is assembled, for example, the disassembled battery is dried in a vacuum at 110°C for 12 hours to evaporate the moisture in the battery container, and the amount of moisture can be calculated from the difference in the mass of the battery before and after drying. The amount of moisture in the battery container shown in the examples below is a value determined by calculating the amount of moisture in the electrolyte by the former method.

[0028] <Alkaline electrolyte> In the button alkaline battery of the present invention, an alkaline aqueous solution is used as the electrolyte. As the electrolyte to be contained, an alkali metal hydroxide (sodium hydroxide, potassium hydroxide, lithium hydroxide, etc.) is preferably used, and potassium hydroxide is particularly preferably used. Regarding the concentration of the electrolyte, for example, in the case of an aqueous solution of potassium hydroxide, the concentration of potassium hydroxide is preferably 20 mass% or more, more preferably 28 mass% or more. On the other hand, in order to increase the ion conductivity, the concentration of potassium hydroxide is preferably 40 mass% or less, more preferably 35 mass% or less. By adjusting the concentration of the aqueous solution of potassium hydroxide to such a value, a battery with better load characteristics can be constructed.

[0029] In addition to the above-mentioned components, various known additives may be added to the electrolyte as necessary within the range that does not impair the effects of the present invention. For example, zinc oxide, tin oxide, indium oxide, etc. may be added to suppress corrosion (oxidation) of zinc particles.

[0030] <Positive electrode> The positive electrode according to the present invention is configured using a molded body (positive electrode mixture layer) produced by pressure molding a positive electrode mixture containing at least silver oxide (silver(I) oxide, silver(II) oxide, silver-nickel composite oxide, etc.) as a positive electrode active material and a conductive assistant.

[0031] The silver oxide used in the positive electrode is preferably in a granular form. Usually, silver oxide is provided in the form of a fine powder having a particle size of 0.1 to 5 μm, but when this silver oxide is granulated and used in the form of granules, the resistance is lower than when the silver oxide is used in the form of a fine powder, and therefore the load characteristics of the battery can be improved.

[0032] When silver oxide is used in the form of fine powder, it is necessary to add a larger amount of conductive assistant to reduce the resistance, which leads to a decrease in capacity. On the other hand, when granular silver oxide is used, the weighing property is improved, and the weight variation of the positive electrode is reduced. In addition, when the silver oxide is pressed, the filling property is improved and the moldability is improved, so that the resistance is reduced and the variation in the individual characteristics of the battery can be reduced. Furthermore, the amount of carbonaceous material and the like added as a conductive assistant can be reduced, and the required capacity can be secured.

[0033] When the granular silver oxide is used, the particle size is preferably 50 μm or more, more preferably 75 μm or more, and is preferably 500 μm or less, more preferably 300 μm or less. The bulk density is 1.5 g / cm 3 It is preferable that the content is 1.8 g / cm or more. 3 More preferably, it is 3.5 g / cm or more. 3 It is preferable that the density is 2.6 g / cm or less. 3 It is more preferable that the silver oxide is less than 100%. Silver oxide in this form has better fluidity than powdered silver oxide, and as mentioned above, it has improved weighing and moldability, and the resistance is reduced, improving reactivity. This leads to better load characteristics of the battery, and also reduces the variation in characteristics of individual batteries. The particle size of the granular silver oxide used here is measured using a laser diffraction / scattering type particle size distribution (particle size distribution) measuring device. The bulk density of the granular silver oxide is measured by putting a specified amount of granular silver oxide into a container and measuring it using a bulk density measuring device in accordance with the bulk density measuring method specified in JIS R 1628.

[0034] The positive electrode may contain an active material other than silver oxide, and manganese dioxide, nickel oxyhydroxide, or the like may be mixed with silver oxide.

[0035] The positive electrode according to the present invention contains carbon black and graphite particles as conductive assistants. By using these carbonaceous particles in combination, a positive electrode mixture layer having an appropriate density is formed, which makes it easier to absorb and retain the electrolyte, and even if the amount of water in the battery container is increased, the occurrence of leakage and assembly failure can be suppressed, and the conductivity of the positive electrode can be increased, thereby improving the load characteristics of the battery.

[0036] The density of the positive electrode mixture layer is 5.2 g / cm to increase the conductivity. 3 On the other hand, in order to easily absorb and retain the electrolyte, it is preferable to set the thickness to 5.5 g / cm 3 It is preferable that:

[0037] Examples of the carbon black include furnace black, channel black, acetylene black, and thermal black. Acetylene black, which has high conductivity and few impurities, is preferably used. Carbon black is a black having a BET specific surface area of ​​85 m2 or less in order to suppress the generation of gas due to functional groups and impurities on the surface. 2 On the other hand, in order to form a good conductive network, the BET specific surface area of ​​carbon black is preferably 15 m 2 It is preferable that the molecular weight is 1 / g or more.

[0038] The graphite particles preferably have an average particle size of 1 μm or more to improve the formability of the positive electrode mixture layer, and preferably have an average particle size of 7 μm or less to improve the electrical conductivity. The ratio of carbon black to graphite particles is preferably in the range of 20:80 to 50:50 by mass.

[0039] The content of the conductive assistant in the positive electrode mixture layer is preferably 4% by mass or more in order to increase the conductivity of the positive electrode, and is preferably 8% by mass or less in order to increase the proportion of the positive electrode active material and increase the discharge capacity. The positive electrode mixture layer may contain a conductive assistant (such as carbon fiber) other than carbon black and graphite particles, but the conductive assistant contained in the positive electrode mixture layer may be only carbon black and graphite particles.

[0040] The positive electrode can be produced, for example, by pressurizing a positive electrode mixture prepared by mixing a positive electrode active material, a conductive assistant, an alkaline electrolyte, and the like into a predetermined shape.

[0041] It is possible to prevent the problem of leakage during assembly or storage of the battery by reducing the amount of active material filled in the negative or positive electrode to increase the void space in the battery container. However, since reducing the amount of active material leads to a decrease in the capacity of the battery, it is desirable to configure a battery with excellent load characteristics by keeping the amount of water in the battery container within the above range even when a certain amount of active material is filled, that is, when there is little void space in the battery container.

[0042] In the present invention, for example, when the internal volume of the sealing plate with a resin gasket attached (the volume of the voids that can be filled with zinc particles) is a (μL) and the mass of the zinc particles filled inside the sealing plate is b (mg), even if the value of b / a is 1 or more, that is, the zinc particles occupy approximately 14% or more of the internal volume of the sealing plate, it is possible to configure a battery with excellent load characteristics while preventing problems such as leakage and assembly defects that occur when the moisture content in the battery container is within the above-mentioned range.

[0043] Here, "the internal volume of the sealing plate with the resin gasket attached" means the volume of the space formed from the inner bottom surface of the sealing plate to the open end of the gasket.

[0044] Furthermore, in the present invention, the side surface of the positive electrode mixture layer is in contact with the inner surface of the outer can, that is, in the sealed state, there is substantially no gap formed between the positive electrode mixture layer and the outer can, or the gap is limited to between the bottom surface of the positive electrode mixture layer and the inner bottom surface of the outer can, and even in a case where, for example, the positive electrode mixture layer occupies 78% or more of the internal volume of the outer can side inside the battery container, it is possible to configure a battery with excellent load characteristics while preventing problems such as leakage and assembly defects that occur when the moisture content inside the battery container is within the above-mentioned range.

[0045] In order to increase the discharge capacity of the battery, the value of b / a is preferably 1.1 or more, and more preferably 1.15 or more. On the other hand, in consideration of the volume expansion of the negative electrode caused by the discharge of zinc particles and the formation of zinc oxide, in order to ensure a certain degree of void inside the sealing plate, the value of b / a is preferably 2 or less, and more preferably 1.5 or less.

[0046] In order to increase the discharge capacity of the battery, the ratio of the internal volume of the battery container on the exterior can side that is occupied by the positive electrode material mixture layer is preferably 82% or more, and more preferably 85% or more, while in order to ensure a space for accommodating a separator, etc., the ratio of the internal volume of the battery container on the exterior can side that is occupied by the positive electrode material mixture layer is preferably 97% or less, and more preferably 94% or less.

[0047] Here, "the internal volume of the battery container on the exterior can side" means the volume of the space formed within the battery container between the inner bottom surface of the exterior can and the bottom surface and opening end of the gasket.

[0048] There is no particular limitation on the separator for the button alkaline battery of the present invention, and examples of the separator that can be used include nonwoven fabrics mainly made of vinylon and rayon, vinylon-rayon nonwoven fabrics (vinylon-rayon mixed paper), polyamide nonwoven fabrics, polyolefin-rayon nonwoven fabrics, vinylon paper, vinylon-linter pulp paper, vinylon-mercerized pulp paper, and graft films made of graft copolymers having a structure in which acrylic acid is graft-copolymerized onto a polyethylene main chain. Also, a separator made by stacking a hydrophilically treated microporous polyolefin film (such as a microporous polyethylene film or a microporous polypropylene film), a cellophane film, and a liquid-absorbing layer such as vinylon-rayon mixed paper may be used.

[0049] For example, nickel-plated iron or stainless steel can be used for the exterior can of the button alkaline battery. For the sealing plate, iron or stainless steel can be used with a metal layer made of copper or a copper alloy such as brass formed on the inner surface. It is more preferable to further form a tin layer on the surface of the metal layer. The metal layer made of copper or a copper alloy is formed on the inner surface of the sealing plate in order to prevent the formation of a local battery with zinc and thus prevent the corrosion of zinc. However, by further forming a tin layer on the surface of the metal layer, the corrosion prevention effect can be further enhanced.

[0050] The exterior can and the sealing plate are sealed with a gasket interposed therebetween to assemble a button alkaline battery. The gasket can be made of a resin such as polypropylene or nylon that is resistant to an alkaline aqueous solution. EXAMPLES

[0051] The present invention will be described in detail below with reference to examples, although the present invention is not limited to the following examples.

[0052] Example 1 <Preparation of positive electrode> As a positive electrode active material, the average particle size is 150 μm and the bulk density is 2.4 g / cm 3Granulated silver oxide: 94.3 parts by mass, BET specific surface area: 68 m 2 / g, acetylene black particles with an average primary particle diameter of 35 nm: 1.9 parts by mass, BET specific surface area: 20 m 2 A mixture was prepared by mixing 3.8 parts by mass of graphite particles having an average particle size of 3.7 μm and 84 mg of the mixture, which was then press-molded into a disk shape to obtain a packing density of 5.35 g / cm. 3 Thus, a positive electrode mixture compact (positive electrode mixture layer) having a diameter of 6.4 mm was produced.

[0053] <Battery assembly> For the negative electrode, mercury-free zinc particles were used, with an average particle size of 120 μm, 10 mass% or less of particles with a particle size of 75 μm or less, and 90 mass% or more of particles with a particle size of 100 to 150 μm, and containing 0.05 mass% (500 ppm) In, 0.04 mass% (400 ppm) Bi, and 0.001 mass% (10 ppm) Al.

[0054] A gasket made of nylon 66 was attached to a sealing plate made of a copper-stainless steel-nickel three-layer clad plate, and 21 mg of the zinc particles were filled into the space inside. Furthermore, 12 μL of an alkaline electrolyte consisting of an aqueous solution in which potassium hydroxide and zinc oxide were dissolved at concentrations of 30.6% by mass and 4% by mass, respectively, was poured in to form a negative electrode.

[0055] The internal volume of the sealing plate with the gasket attached was 18 μL, and the ratio of the mass of the zinc particles to the internal volume of the sealing plate was 1.17.

[0056] After injecting 8 μL of the same alkaline electrolyte as above into an exterior can with an inner diameter of 6.4 mm made of SUS430, the positive electrode was placed therein, and the side and bottom of the positive electrode (positive electrode mixture layer) were brought into contact with the inner side and bottom of the exterior can, respectively. Furthermore, a laminated film (YG2152 manufactured by Yuasa Membrane Systems Co., Ltd.) in which a cellophane film with a thickness of 20 μm and a graft film with a thickness of 30 μm composed of a graft copolymer having a structure in which acrylic acid is graft-copolymerized to a polyethylene main chain were laminated, and a vinylon-rayon mixed paper with a thickness of 100 μm was placed on the positive electrode, and the electrolyte was absorbed into the positive electrode and the mixed paper, and the sealing plate and the exterior can were sealed via the gasket to prepare a button-type alkaline battery.

[0057] In addition, in the battery of Example 1, no leakage of electrolyte was observed during assembly of the battery.

[0058] The amount of water in the battery container was 0.84 g per 1 g of negative electrode zinc particles, and the ratio of the positive electrode mixture layer to the internal volume of the outer can was 88%. In addition, because the change in the internal volume of the sealing plate before and after sealing was small, the ratio b / a of the mass of the filled zinc particles to the internal volume of the sealing plate was set to 1.17.

[0059] Example 2 A button-type alkaline battery was produced in the same manner as in Example 1, except that the amount of alkaline electrolyte injected into the exterior can was changed to 4 μL.

[0060] It should be noted that no leakage of electrolyte was observed during assembly of the battery in Example 2. The amount of water in the battery container was 0.67 g per 1 g of zinc particles in the negative electrode.

[0061] Example 3 A button-type alkaline battery was produced in the same manner as in Example 1, except that the amount of alkaline electrolyte injected into the exterior can was changed to 6 μL.

[0062] It should be noted that no leakage of electrolyte was observed during assembly of the battery in Example 3. The amount of water in the battery container was 0.76 g per 1 g of zinc particles in the negative electrode.

[0063] Example 4 A button-type alkaline battery was produced in the same manner as in Example 1, except that the alkaline electrolyte was changed to a 36 mass % aqueous potassium hydroxide solution.

[0064] It should be noted that no leakage of electrolyte was observed during assembly of the battery in Example 4. The amount of water in the battery container was 0.86 g per 1 g of zinc particles in the negative electrode.

[0065] Example 5 As a positive electrode active material, the average particle size is 150 μm and the bulk density is 2.4 g / cm 3 Granulated silver oxide: 91.3 parts by mass, BET specific surface area: 68 m 2 / g, acetylene black particles with an average primary particle diameter of 35 nm: 1.9 parts by mass, BET specific surface area: 20 m 2 / g, graphite particles with an average particle size of 3.7 μm: 3.8 parts by mass, TeO 2 Powder: 3 parts by mass were mixed to prepare a mixture, and 87 mg of this mixture was pressed into a disk shape to obtain a packing density of 5.35 g / cm 3 A positive electrode mixture compact (positive electrode mixture layer) having a diameter of 6.4 mm was produced. A button-type alkaline battery was produced in the same manner as in Example 1, except that this compact was used as the positive electrode.

[0066] In addition, in the battery of Example 5, leakage of electrolyte was not confirmed during assembly of the battery. The amount of water in the battery container was 0.84g per 1g of zinc particles of the negative electrode, and the ratio of the positive electrode mixture layer to the internal volume of the outer can side was 92%. In addition, the ratio value of the mass of the filled zinc particles to the internal volume of the sealing plate: b / a was 1.17.

[0067] Comparative Example 1 A button-type alkaline battery was produced in the same manner as in Example 1, except that the amount of alkaline electrolyte injected into the exterior can was changed to 2.5 μL.

[0068] It should be noted that no leakage of electrolyte was observed during assembly of the battery in Comparative Example 1. The amount of water in the container of this battery was 0.61 g per 1 g of zinc particles in the negative electrode.

[0069] Comparative Example 2 The alkaline electrolyte to be injected into the outer can is 10 μL, and the alkaline electrolyte to be injected into the negative electrode is A button-type alkaline battery was prepared in the same manner as in Example 1, except that the solution was changed to 14.5 μL. Made.

[0070] In Comparative Example 2, leakage of electrolyte was confirmed in about 80% of the assembled batteries. The amount of water in the battery container was 1.03 g per 1 g of zinc particles in the negative electrode for the batteries that did not leak electrolyte.

[0071] Comparative Example 3 As a positive electrode active material, the average particle size is 150 μm and the bulk density is 2.4 g / cm 3 Granulated silver oxide: 94.3 parts by mass, BET specific surface area: 20 m 2 5.7 parts by mass of graphite particles having an average particle size of 3.7 μm were mixed to prepare a mixture, and 91 mg of this mixture was press-molded into a disk shape to obtain a packing density of 5.8 g / cm. 3 A positive electrode mixture compact (positive electrode mixture layer) having a diameter of 6.4 mm was produced using this compact as a positive electrode, and a button-type alkaline battery was produced in the same manner as in Example 1, except that the amount of alkaline electrolyte injected into the exterior can was 2 μL.

[0072] In Comparative Example 3, no leakage of electrolyte was observed during assembly of the battery. The amount of water in the battery container was 0.61 g per 1 g of zinc particles of the negative electrode, and the proportion of the positive electrode mixture layer in the internal volume of the outer can side was 88%. In addition, the ratio of the mass of the filled zinc particles to the internal volume of the sealing plate: b / a, was 1.17.

[0073] Comparative Example 4 A button-type alkaline battery was produced in the same manner as in Comparative Example 3, except that the amount of alkaline electrolyte injected into the exterior can was changed to 8 μL.

[0074] In Comparative Example 4, leakage of electrolyte was confirmed in about 60% of the assembled batteries. The amount of water in the battery container was 0.84 g per 1 g of zinc particles in the negative electrode for the batteries that did not leak electrolyte.

[0075] Table 1 shows the type and content of the conductive additive in the positive electrode mixture layer, the amount of moisture in the battery container (per 1 g of zinc particles), and whether or not assembly defects (electrolyte leakage) occurred for each battery produced.

[0076] [Table 1]

[0077] The following measurements were carried out on each of the batteries of Examples 1 to 5 and Comparative Examples 1 and 3, which did not experience leakage of electrolyte during assembly.

[0078] <Battery internal resistance> The impedance at 1 kHz was measured by an AC impedance method, and the value was calculated as the internal resistance of the battery.

[0079] <Battery discharge capacity> The battery was discharged at a constant current of 0.05 mA at room temperature, and the discharge capacity until the battery voltage decreased to 1 V was determined.

[0080] <Battery load characteristics> The battery was discharged at constant currents of 20 mA and 80 mA at room temperature, and the battery voltage (closed circuit voltage) was measured 10 ms after the start of discharge to evaluate the load characteristics of the battery.

[0081] The measurement results are shown in Table 2.

[0082] [Table 2]

[0083] In the batteries of Examples 1 to 5, carbon black and graphite particles were contained as conductive assistants in the positive electrode mixture layer, so that leakage of electrolyte could be prevented even if the amount of water in the battery container was increased to the range of 0.63 to 1 g per 1 g of zinc particles in the negative electrode. Therefore, a button-type alkaline battery with excellent load characteristics and high reliability could be constructed.

[0084] In contrast, in the batteries of Comparative Example 1 and Comparative Example 3, in which the amount of water in the battery container was less than the range of the present invention, the internal resistance of the battery increased and the load characteristics deteriorated. In particular, in Comparative Example 3, in which only graphite particles were contained as the conductive assistant in the positive electrode mixture layer, the characteristics deteriorated more significantly. On the other hand, in the battery of Comparative Example 2, in which the amount of water in the battery container was more than the range of the present invention, leakage of the electrolyte was observed in some of the batteries.

[0085] In addition, batteries that contained only graphite particles as a conductive assistant in the positive electrode mixture layer were prone to electrolyte leakage during battery assembly, and in Comparative Example 4, in which the amount of water in the battery container was increased to the range of the present invention, electrolyte leakage was observed in some batteries.

[0086] The present invention can be implemented in other forms than those described above 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 description of the appended claims rather than the description of the above specification, and all modifications within the scope of the claims are included in the scope of the claims. [Industrial Applicability]

[0087] The button alkaline battery of the present invention has excellent load characteristics and reliability, and by taking advantage of these characteristics, it can be preferably used in various applications in which conventionally known button alkaline batteries are used, including medical measuring instruments in which discharge is performed under a relatively high load and high reliability is required. [Explanation of symbols]

[0088] 1 alkaline button cell battery 2 Outer can 3 Sealing plate 4 Positive electrode 5 negative electrode 6 Separator 7 Plastic gasket

Claims

1. A button-type alkaline battery in which a positive electrode having a positive electrode mixture layer containing silver oxide and a conductive assistant, a negative electrode containing zinc particles, and an alkaline electrolyte are accommodated in a battery container that is composed of an outer can, a sealing plate, and a resin gasket, The positive electrode mixture layer contains carbon black and graphite particles as the conductive assistant, and the amount of water in the battery container is 0.63 to 1 g per 1 g of zinc particles of the negative electrode.

2. 2. The button-type alkaline battery according to claim 1, wherein the ratio b / a of the internal volume a (μL) of the sealing plate with the resin gasket attached to the mass b (mg) of the zinc particles filled inside the sealing plate is 1 or greater.

3. 3. The button-type alkaline battery according to claim 1, wherein the volume of the positive electrode mixture layer occupies 78% or more of the internal volume of the battery container on the exterior can side.

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