Alkaline batteries

Abstract

An alkaline battery according to the present invention is provided with: a closed-bottom cylindrical case; a hollow cylindrical positive electrode in contact with the inside of the case; a negative electrode which fills the hollow interior of the positive electrode and includes a negative electrode active substance including zinc; a separator disposed between the positive electrode and the negative electrode; an alkaline electrolyte; and a sealing unit. The alkaline electrolyte is contained in the positive electrode, the negative electrode, and the separator. The sealing unit is provided with a negative electrode collector body which covers the opening in the case and is partially inserted into the negative electrode. An additive fills the space between the negative electrode and the sealing unit. The additive includes a wax component having a melting point between 60°C and 110°C, inclusive. The wax component includes at least one selected from the group consisting of an aliphatic hydrocarbon compound and an ester compound.

Description

Technical Field

[0001] The present disclosure relates to an alkaline dry battery.

Background Art

[0002] Alkaline dry batteries (alkaline manganese dry batteries) are widely used because they have a larger capacity than manganese dry batteries and can discharge a large current.

[0003] In Patent Document 1, a positive electrode mixture and a gel-like negative electrode mixture are accommodated in a bottomed cylindrical positive electrode can via a separator, and in an alkaline battery in which a hole in the central portion of the bottom of the separator is closed with a separator material, the separator material is a thermoplastic resin that melts and softens in the temperature rise process due to heat generation caused by a short circuit outside the battery to release the closure of the hole, and an internal short circuit path connecting between the gel-like negative electrode mixture and the bottom of the positive electrode can can be formed as the thermoplastic resin melts and softens. An alkaline battery has been proposed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

Means for Solving the Problems

[0006] One aspect of the present disclosure relates to an alkaline dry cell comprising: a bottomed cylindrical case; a hollow cylindrical positive electrode inscribed within the case; a negative electrode filled in the hollow portion of the positive electrode and containing a zinc-containing negative electrode active material; a separator disposed between the positive electrode and the negative electrode; an alkaline electrolyte contained in the positive electrode, the negative electrode and the separator; and a sealing unit comprising a negative electrode current collector covering the opening of the case and partially inserted into the negative electrode, wherein an additive is filled in the gap between the negative electrode and the sealing unit, the additive includes a wax component having a melting point of 60°C or higher and 110°C or lower, and the wax component includes at least one selected from the group consisting of aliphatic hydrocarbon compounds and ester compounds.

[0007] Another aspect of the present disclosure relates to an alkaline dry cell comprising a bottomed cylindrical case, a hollow cylindrical positive electrode inscribed within the case, a negative electrode filled in the hollow portion of the positive electrode and containing a zinc-containing negative electrode active material, a separator disposed between the positive electrode and the negative electrode, an alkaline electrolyte contained in the positive electrode, the negative electrode and the separator, and a sealing unit comprising a negative electrode current collector covering the opening of the case and partly inserted into the negative electrode, wherein an additive is filled in the gap between the negative electrode and the sealing unit, the additive includes a wax component having an endothermic onset temperature of 50°C or higher and 85°C or lower in differential scanning calorimetry, and the wax component includes at least one selected from the group consisting of aliphatic hydrocarbon compounds and ester compounds. [Effects of the Invention]

[0008] According to this disclosure, it is possible to suppress the temperature rise of an alkaline battery when it is short-circuited externally.

[0009] While novel features of the present invention are described in the appended claims, the present invention, both in terms of its structure and content, will be better understood by the following detailed description in conjunction with the drawings, in conjunction with other objects and features of the present invention. [Brief explanation of the drawing]

[0010] [Figure 1]This is a front view showing a cross-section of a part of an alkaline dry cell in one embodiment of the present disclosure. [Figure 2] This is a front view showing a cross-section of a portion of the alkaline battery of Comparative Example 2. [Modes for carrying out the invention]

[0011] The embodiments of this disclosure will be described below with examples, but this disclosure is not limited to the examples described below. In the following description, specific numerical values ​​and materials may be given as examples, but other numerical values ​​and materials may be applied as long as the effects of this disclosure are obtained. In this specification, the description "numerical value A to numerical value B" includes numerical value A and numerical value B, and can be read as "greater than or equal to numerical value A and less than or equal to numerical value B". In the following description, when lower and upper limits of numerical values ​​relating to specific physical properties or conditions are given as examples, either of the given lower limits and either of the given upper limits can be arbitrarily combined, as long as the lower limit is not greater than or equal to the upper limit. When multiple materials are given as examples, one of them may be selected and used alone, or two or more may be used in combination.

[0012] An alkaline dry cell according to an embodiment of this disclosure comprises a bottomed cylindrical case, a hollow cylindrical positive electrode inscribed within the case, a negative electrode filled in the hollow portion of the positive electrode, a separator disposed between the positive electrode and the negative electrode, an alkaline electrolyte, and a sealing unit covering the opening of the case. The negative electrode contains a negative electrode active material containing zinc. The alkaline electrolyte is contained in the positive electrode, the negative electrode, and the separator. The sealing unit comprises a negative electrode current collector, a portion of which is inserted into the negative electrode. An additive is filled in the gap between the negative electrode and the sealing unit. The additive includes a wax component having a melting point of 60°C or higher and 110°C or lower (or a wax component having an endothermic onset temperature of 50°C or higher and 85°C or lower in differential scanning calorimetry). The wax component includes at least one selected from the group consisting of aliphatic hydrocarbon compounds and ester compounds.

[0013] The melting point mentioned above refers to the value measured by general methods described in standards such as the Japanese Industrial Standard (JIS K 0064). If necessary, the melting point may also be measured by thermogravimetric differential thermal analysis (TG / DTA).

[0014] When the battery temperature rises due to an external short circuit, the wax component begins to melt. As the wax component melts, the heat generated by the external short circuit is absorbed, thereby suppressing the temperature rise during the external short circuit. A portion of the negative electrode current collector is exposed in the gap between the negative electrode and the sealing unit. Since the negative electrode current collector is prone to overheating during an external short circuit, filling this gap with an additive allows the heat-absorbing effect associated with the melting of the wax component to be efficiently exerted on the negative electrode current collector, sufficiently suppressing the rise in battery temperature. It is desirable that the additive be filled in this gap in direct contact with the negative electrode current collector.

[0015] The gap can be filled with the amount of wax component necessary to suppress the temperature rise during an external short circuit. Since the additive is filled in the gap between the negative electrode and the sealing unit, there is almost no effect on the discharge performance due to the filling of the additive.

[0016] Wax components with a melting point of 60°C or higher and 110°C or lower (or wax components with an endothermic onset temperature of 50°C or higher and 85°C or lower in differential scanning calorimetry) exist as solids during normal battery use (storage) and begin to melt when an external short circuit occurs. While the wax components exist as solids within the battery, their diffusion into the negative electrode is suppressed, and the filling of wax components does not affect discharge performance. The melting point of the wax components may also be 65°C or higher (or 70°C or higher) and 100°C or lower.

[0017] If the melting point of the wax component is below 60°C or above 110°C, the wax component may not melt sufficiently during an external short circuit, and the heat-absorbing effect due to the melting of the wax component may not be fully exerted against the heat generated by the negative electrode current collector during an external short circuit. Also, if the melting point of the wax component is below 60°C, the wax component may diffuse into the negative electrode during normal battery use, affecting the discharge performance.

[0018] The endothermic start temperature T in the differential scanning calorimetry (DSC) of the above wax component A is preferably 50°C or higher and 85°C or lower, and more preferably 55°C or higher and 85°C or lower. In this case, the endothermic effect due to the melting of the wax component is efficiently exerted against the heat generation of the negative electrode current collector during an external short circuit, and the temperature rise during an external short circuit is easily suppressed.

[0019] The peak temperature of the maximum endothermic peak in the DSC of the above wax component is, for example, 65°C or higher and 90°C or lower. The above peak temperature is obtained from the DSC curve described later.

[0020] The above endothermic start temperature T A is obtained as follows. Using a differential scanning calorimeter, a DSC curve of the wax component is obtained. The measurement conditions are, for example, measurement temperature range: 0°C to 150°C, heating rate: 10°C / min, measurement atmosphere: nitrogen. For the differential scanning calorimeter, for example, the "DSC-60 Plus series" manufactured by Shimadzu Corporation is used. In the DSC curve, the temperature at point A where the heat flow (mW) starts to decrease from the low-temperature baseline B and heads towards the endothermic peak P is taken as the endothermic start temperature T A and determined as such. Note that the vertical and horizontal axes of the graph showing the DSC curve are heat flow (mW) and temperature (°C), respectively. When multiple endothermic peaks appear, the above endothermic peak P refers to the endothermic peak that appears on the lowest temperature side.

[0021] The wax component contains at least one selected from the group consisting of aliphatic hydrocarbon compounds and ester compounds. For the component analysis of the wax component, for example, gas chromatography-mass spectrometry (GC-MS), proton nuclear magnetic resonance spectroscopy ( 1 1H-NMR), etc. are used.

[0022] Aliphatic hydrocarbon compounds include linear saturated aliphatic hydrocarbon compounds, branched saturated aliphatic hydrocarbon compounds, and alicyclic saturated aliphatic hydrocarbon compounds. The number of carbon atoms in aliphatic hydrocarbon compounds is, for example, 20 to 60. Aliphatic hydrocarbon compounds may be used individually or in combination of two or more types.

[0023] Ester compounds include fatty acid ester compounds and hydroxy acid ester compounds. Fatty acid ester compounds include condensation reaction products of higher fatty acids and higher alcohols. The number of carbon atoms in higher fatty acids is, for example, 6 to 40. The number of carbon atoms in higher alcohols is, for example, 10 to 30. Hydroxy acid ester compounds include condensation reaction products of hydroxy acids and higher alcohols. The number of carbon atoms in hydroxy acids is, for example, 6 to 40. The number of carbon atoms in higher alcohols is, for example, 10 to 30. Ester compounds may be used individually or in combination of two or more.

[0024] The wax component may include hydrocarbon (petroleum-based) waxes. Examples of hydrocarbon waxes include paraffin wax and microcrystalline wax. Paraffin wax contains linear saturated aliphatic hydrocarbon compounds. The number of carbon atoms in the hydrocarbon compounds contained in paraffin wax is, for example, 20 to 50. Microcrystalline wax contains branched saturated aliphatic hydrocarbon compounds and cyclic saturated aliphatic hydrocarbon compounds. The number of carbon atoms in the hydrocarbon compounds contained in microcrystalline wax is, for example, 30 to 60. Hydrocarbon waxes may be used individually or in combination of two or more types.

[0025] The wax component may include ester waxes. Ester waxes may contain at least an ester compound, and may also contain an aliphatic hydrocarbon compound (e.g., a linear aliphatic hydrocarbon compound) in addition to the ester compound. Examples of ester waxes include plant-based waxes such as carnauba wax, animal-based waxes such as privet wax, mineral waxes such as bleached montane wax, and hydrogenated oils (synthetic waxes) such as hydrogenated castor oil (hydrogenated castor oil) (melting point approximately 90°C). Ester waxes may be used individually or in combination of two or more types.

[0026] The wax components may further include other components besides aliphatic hydrocarbon compounds and ester compounds. Examples of other components include free fatty acids, free alcohols, and hydrocarbons.

[0027] The amount of wax component filled into the battery may be 10 mg to 200 mg or 50 mg to 200 mg per gram of zinc derived from the negative electrode active material. If the amount of wax component is within the above range, it is easier to fill the predetermined gaps in the battery with the wax component, and the effect of suppressing temperature rise during external short circuits due to the wax component is easily obtained.

[0028] The additive contains at least a wax component. That is, only the wax component may be used as an additive to fill a predetermined gap. The additive may also contain other components besides the wax component. The other components may be components that enhance the binding strength of the solid wax component (e.g., polytetrafluoroethylene), or they may be used in mixture with the powdered wax component. The additive that is filled into a predetermined gap in the battery may be a powder, a pellet, or a weld to the negative electrode current collector and / or gasket. Pellets can be obtained, for example, by pressure molding a powdered wax component or a mixture of a powdered wax component and other components. Welds to the negative electrode current collector and / or gasket can be obtained, for example, by heating the wax component above its melting point and welding it to a predetermined location on the gasket and / or negative electrode current collector (the part exposed in the gap between the negative electrode and the sealing unit). By welding the additive to the part of the gasket that is exposed in the gap between the negative electrode and the sealing unit, the additive can be placed close to the negative electrode current collector.

[0029] Furthermore, from the viewpoint of suppressing the diffusion of the additive into the negative electrode and suppressing the seepage of the electrolyte into the additive, a thin film for partial shielding (e.g., cellophane) may be placed between the negative electrode and the additive.

[0030] The alkaline dry cell according to this embodiment will be described in detail below with reference to the drawings. However, this disclosure is not limited to the following embodiments. Modifications can be made as appropriate without departing from the scope of achieving the effects of this disclosure. Furthermore, combinations with other embodiments are also possible.

[0031] Figure 1 is a front cross-sectional view of the lateral half of an alkaline battery in one embodiment of the present disclosure. Figure 1 shows an example of a cylindrical battery having an inside-out structure.

[0032] As shown in Figure 1, the alkaline dry cell comprises a power generation element including a hollow cylindrical positive electrode 2, a gel-like negative electrode 3 disposed within the hollow portion of the positive electrode 2, a separator 4 disposed between them, and an alkaline electrolyte (not shown). The power generation element is housed in a bottomed cylindrical metal case 1. A protrusion 1a (positive electrode terminal portion) is provided at the bottom of the case 1. For example, nickel-plated steel sheet is used for the case 1. The positive electrode 2 is disposed in contact with the inner wall of the case 1. To improve the adhesion between the positive electrode 2 and the case 1, it is preferable that the inner surface of the case 1 is coated with a carbon film.

[0033] The bottomed cylindrical separator 4 is composed of a cylindrical separator 4a and a bottom paper 4b. Separator 4a is positioned along the inner surface of the hollow portion of the positive electrode 2, separating the positive electrode 2 from the negative electrode 3. Therefore, the separator positioned between the positive and negative electrodes refers to the cylindrical separator 4a. The bottom paper 4b is positioned at the bottom of the hollow portion of the positive electrode 2, separating the negative electrode 3 from the case 1.

[0034] The opening of case 1 is sealed by a sealing unit 9. The sealing unit 9 comprises a resin gasket 5, a negative electrode terminal plate 7 (negative electrode terminal portion), and a negative electrode current collector 6. The negative electrode current collector 6 is inserted into the negative electrode 3. The material of the negative electrode current collector 6 is, for example, an alloy containing copper and zinc, such as brass. The negative electrode current collector 6 may be plated, such as with tin plating, if necessary. The negative electrode current collector 6 has a nail-like shape with a head and a body. The body of the negative electrode current collector 6 is inserted into a through hole provided in the central cylindrical portion of the gasket 5, and the head of the negative electrode current collector 6 is welded to the flat portion in the center of the negative electrode terminal plate 7.

[0035] The open end of case 1 is crimped to the flange portion of the peripheral edge of the negative electrode terminal plate 7 via the outer peripheral edge of the gasket 5. The outer surface of case 1 is covered with an outer label 8.

[0036] In the alkaline battery according to this embodiment, an additive 10 containing a wax component is filled into the gap between the gel-like negative electrode 3 and the sealing unit 9 (the gap formed by the negative electrode 3, the portion of the negative electrode current collector 6 exposed from the negative electrode 3, and the gasket 5). As a result, the heat-absorbing effect of the wax component contained in the additive 10 when it melts is efficiently exerted against the heat generated by the negative electrode current collector 6 during an external short circuit. To ensure that the positive electrode 2 and the negative electrode 3 are securely isolated, the end of the separator 4a on the opening side of the case 1 is positioned to protrude from the end faces on the opening side of the case 1 at the positive electrode 2 and the negative electrode 3, and extends to a position where it normally contacts the sealing unit 9 (gasket 5) which is located at the opening of the case 1. More specifically, the gap between the negative electrode 3 and the sealing unit 9 can be described as the space surrounded by the negative electrode 3, the sealing unit 9 (negative electrode current collector 6 and gasket 5), and the separator 4a.

[0037] The additive 10 can be filled as a ring-shaped pellet containing a wax component. In this case, the body of the negative electrode current collector 6 is placed in the hollow part of the pellet. This allows the additive 10 to be stably positioned in the gap. Furthermore, from the viewpoint of suppressing the diffusion of the additive into the negative electrode and suppressing the seepage of the electrolyte in the negative electrode into the additive, it is preferable to fill the additive 10 as a pellet. Since the separator 4a adjacent to the additive 10 holds the electrolyte, the electrolyte in the separator 4a is less likely to seep into the additive 10.

[0038] From the viewpoint of suppressing the diffusion of the additive into the negative electrode and suppressing the seepage of the electrolyte into the additive, a thin film for partial shielding (e.g., cellophane) may be placed between the gel-like negative electrode 3 and the additive 10.

[0039] Positive electrode 2 contains manganese dioxide, which is the positive electrode active material, and an electrolyte. Electrolytic manganese dioxide is preferred as the manganese dioxide. Manganese dioxide is used in powder form. From the viewpoint of ensuring good packing of the positive electrode and diffusion of the electrolyte within the positive electrode, the average particle size of manganese dioxide is, for example, 20 μm or more and 60 μm or less. From the viewpoint of moldability and suppression of positive electrode expansion, the BET specific surface area of ​​manganese dioxide is, for example, 20 m². 2 / g or more, 50m 2It may also be in a range of less than / g.

[0040] In this specification, the average particle size is the median diameter (D50) in the volume-based particle size distribution. The average particle size can be determined, for example, using a laser diffraction and / or scattering particle size distribution analyzer. The BET specific surface area is the surface area measured and calculated using the BET equation, which is the theoretical formula for multilayer adsorption. The BET specific surface area can be measured, for example, using a specific surface area analyzer based on the nitrogen adsorption method.

[0041] Positive electrode 2 may contain a conductive agent in addition to manganese dioxide and electrolyte. Examples of conductive agents include carbon black such as acetylene black, and conductive carbon materials such as graphite. Natural graphite and artificial graphite can be used as graphite. The conductive agent may be in fibrous form, but is preferably in powder form. The average particle size of the conductive agent can be selected from a range of, for example, 5 nm or more and 50 μm or less. If the conductive agent is carbon black, the average particle size is preferably 5 nm or more and 40 nm or less, and if it is graphite, it is preferably 3 μm or more and 50 μm or less. The content of the conductive agent in the positive electrode mixture is, for example, 3 parts by mass or more and 10 parts by mass or less, preferably 4 parts by mass or more and 8 parts by mass or less, per 100 parts by mass of manganese dioxide.

[0042] Positive electrode 2 is obtained, for example, by pressure molding a positive electrode mixture containing a positive electrode active material, a conductive agent, and an electrolyte into pellets. The positive electrode mixture may first be made into flakes or granules, classified as necessary, and then pressure molded into pellets. After the pellets are placed in a case, they may be subjected to secondary pressure using a predetermined device to ensure they adhere tightly to the inner wall of the case. The average density of manganese dioxide in the positive electrode pellets is, for example, 2.78 g / cm³. 3 More than 3.08g / cm 3 The following applies: The positive electrode (positive electrode mixture) may contain other components (e.g., polytetrafluoroethylene) as needed.

[0043] The negative electrode 3 has a gel-like form. That is, in addition to the negative electrode active material and electrolyte, the negative electrode 3 usually contains a gelling agent. The negative electrode active material contains zinc or a zinc alloy. From the viewpoint of corrosion resistance, the zinc alloy preferably contains at least one selected from the group consisting of indium, bismuth, and aluminum.

[0044] The negative electrode active material is usually used in powder form. From the viewpoint of packing the negative electrode and the diffusibility of the alkaline electrolyte within the negative electrode, the average particle size of the negative electrode active material powder is, for example, 80 μm or more and 200 μm or less, preferably 100 μm or more and 150 μm or less. The content of the negative electrode active material powder in the negative electrode is, for example, 170 parts by mass or more and 220 parts by mass or less per 100 parts by mass of electrolyte.

[0045] As the gelling agent, any known gelling agent used in the field of alkaline dry cell batteries can be used without particular limitation, for example, an absorbent polymer can be used. Examples of such gelling agents include polyacrylic acid and sodium polyacrylate. The amount of gelling agent added is, for example, 0.5 parts by mass or more and 2 parts by mass or less per 100 parts by mass of negative electrode active material.

[0046] For separator 4, for example, nonwoven fabric or microporous membrane can be used. Examples of separator materials include cellulose and polyvinyl alcohol. For nonwoven fabric, for example, one mainly composed of fibers of these materials can be used. For microporous membrane, cellophane can be used. The thickness of the separator is, for example, 80 μm or more and 300 μm or less. The separator may also be constructed by layering multiple sheets (nonwoven fabric, etc.) so that the thickness falls within the above range.

[0047] In Figure 1, the bottomed cylindrical separator 4 is composed of a cylindrical separator 4a and a bottom paper 4b, but it is not limited to this. A single bottomed cylindrical separator may be used, and separators of known shapes used in the field of alkaline dry cell batteries can be used.

[0048] For example, an aqueous potassium hydroxide solution is used as the electrolyte. The concentration of potassium hydroxide in the electrolyte is, for example, 30% by mass or more and 50% by mass or less. The electrolyte may also contain zinc oxide. The concentration of zinc oxide in the electrolyte is, for example, 1% by mass or more and 5% by mass or less.

[0049] [Examples] The present disclosure will be described below in detail based on examples and comparative examples, but the present disclosure is not limited to the following examples.

[0050] Examples 1-12 The cylindrical alkaline battery (LR6) shown in Figure 1 was fabricated using the following procedure. (Fabrication of the positive electrode) A mixture was obtained by adding graphite powder (average particle size 8 μm), a conductive agent, to electrolytic manganese dioxide powder (average particle size 35 μm), which was the positive electrode active material. The mass ratio of electrolytic manganese dioxide powder to graphite powder was 92.4:7.6. 1.5 parts by mass of electrolyte was added to 100 parts by mass of the mixture, and after thorough stirring, it was compressed into flakes to obtain a positive electrode mixture. An alkaline aqueous solution containing potassium hydroxide (concentration 35% by mass) and zinc oxide (concentration 2% by mass) was used as the electrolyte.

[0051] Flake-shaped positive electrode mixture was crushed into granules, which were then classified using a 10-100 mesh sieve. The resulting granules were then pressure-molded into a predetermined hollow cylindrical shape to produce two positive electrode pellets.

[0052] (Fabrication of the negative electrode) A gel-like negative electrode 3 was obtained by mixing the negative electrode active material, electrolyte, and gelling agent. The negative electrode active material used was a zinc alloy powder (average particle size 130 μm) containing 0.02 mass% indium, 0.01 mass% bismuth, and 0.005 mass% aluminum. The same electrolyte used in the preparation of the positive electrode was used. A mixture of crosslinked branched polyacrylic acid and highly crosslinked chain sodium polyacrylate was used as the gelling agent. The mass ratio of the negative electrode active material, electrolyte, and gelling agent was 100:50:1.

[0053] (Assembly of alkaline batteries) A bottomed cylindrical case (outer diameter 13.80 mm, height 50.3 mm) made of nickel-plated steel sheet was prepared by forming a carbon film (thickness approximately 10 μm) on its inner surface to obtain case 1. Two positive electrode pellets were inserted vertically into case 1, and then pressurized to form positive electrode 2 that was in close contact with the inner wall of case 1. A bottomed cylindrical separator 4 was placed inside positive electrode 2, and then electrolyte was injected to impregnate the separator 4. The same electrolyte used for preparing the positive electrode was used. This state was left for a predetermined time to allow the electrolyte to permeate from separator 4 to positive electrode 2.

[0054] Subsequently, a predetermined amount of gel-like negative electrode 3 was filled inside the separator 4. Additive 10 was placed on top of the negative electrode 3. For additive 10, ring-shaped pellets obtained by pressure molding powdered wax components were used. Various wax components shown in Table 1 were used for the wax components. For each wax component, if it contained an aliphatic hydrocarbon compound and / or an ester compound, a circle (○) was marked in the column for that compound in Table 1. The amount of wax component filled (amount per 1g of zinc derived from the negative electrode active material) was the value shown in Table 1.

[0055] The separator 4 was constructed using a cylindrical separator 4a and a base paper 4b. The cylindrical separator 4a and the base paper 4b were made of a nonwoven fabric sheet mainly composed of rayon fibers and polyvinyl alcohol fibers in a mass ratio of 1:1. The thickness of the nonwoven fabric sheet used for the base paper 4b was 0.27 mm. The separator 4a was constructed by winding a 0.09 mm thick nonwoven fabric sheet in three layers.

[0056] The negative electrode current collector 6 was obtained by press-forming a general brass (Cu content: approximately 65 mass%, Zn content: approximately 35 mass%) into a nail shape and then plating the surface with tin. The head of the negative electrode current collector 6 was electrically welded to the negative electrode terminal plate 7 made of nickel-plated steel sheet. Then, the body of the negative electrode current collector 6 was press-fitted into the through-hole of the resin gasket 5. In this way, a sealing unit 9 consisting of the gasket 5, the negative electrode terminal plate 7, and the negative electrode current collector 6 was manufactured.

[0057] Next, the sealing unit 9 was installed in the opening of case 1. At this time, the body of the negative electrode current collector 6 was passed through the hollow part of the ring-shaped pellet (additive 10) and inserted into the negative electrode 3. The open end of case 1 was crimped to the periphery of the negative electrode terminal plate 7 via the gasket 5, sealing the opening of case 1. The outer surface of case 1 was covered with the outer label 8. In this way, an alkaline dry cell was manufactured in which the additive 10 was filled in the gap between the negative electrode 3 and the sealing unit 9. In Table 1, A1 to A12 are the batteries of Examples 1 to 12.

[0058] Comparative Example 1 Comparative Example 1's battery X1 was prepared in the same manner as battery A1 of Example 1, except that the additive 10 was not filled into the gap between the negative electrode 3 and the sealing unit 9.

[0059] Comparative Example 2 Instead of filling with additive 10, as shown in Figure 2, additive 20 was filled into the gap between the negative electrode 3 and the bottom of case 1 (the void formed by the convex portion 1a, which is the positive electrode terminal). Additive 20 used was paraffin wax, which is a wax component. The amount of wax component filled (amount per gram of zinc derived from the negative electrode active material) was 50 mg. Except as described above, battery X2 of Comparative Example 2 was prepared in the same manner as battery A1 of Example 1.

[0060] [evaluation] For each of the batteries prepared as described above, the surface temperature of the battery (near the center in the height direction of the case) was measured when an external short circuit was applied, and the highest temperature at that time was determined.

[0061] The evaluation results are shown in Table 1. Note that the filling amount in Table 1 represents the amount (mg) of wax component filled per gram of zinc derived from the negative electrode active material contained in the negative electrode.

[0062] [Table 1]

[0063] With batteries A1 to A12, the temperature rise during an external short circuit was suppressed more effectively than with batteries X1 to X2.

[0064] In battery X1, the battery temperature rose during an external short circuit because no additive was filled in. In battery X2, where an additive was filled in the gap between the bottom of the case and the negative electrode, the additive was filled at a location away from the negative electrode current collector. As a result, the heat generated by the negative electrode current collector during an external short circuit was not sufficiently absorbed by the additive, and the rise in battery temperature could not be suppressed. [Industrial applicability]

[0065] The alkaline dry cell battery according to this disclosure is suitably used as a power source for, for example, portable audio devices, electronic games, lights, and the like.

[0066] Although the present invention has been described in relation to preferred embodiments at present, such disclosure should not be interpreted restrictively. Various modifications and alterations will undoubtedly become apparent to those skilled in the art in the field to which the invention pertains by reading the above disclosure. Accordingly, the appended claims should be interpreted as encompassing all modifications and alterations without departing from the true spirit and scope of the invention. [Explanation of Symbols]

[0067] 1: Case, 1a: Protrusion, 2: Positive electrode, 3: Negative electrode, 4: Bottomed cylindrical separator, 4a: Cylindrical separator, 4b: Bottom paper, 5: Gasket, 6: Negative electrode current collector, 7: Negative electrode terminal plate, 8: Outer label, 9: Sealing unit, 10: Additive

Claims

1. A cylindrical case with a bottom, A hollow cylindrical positive electrode is inscribed within the aforementioned case, The negative electrode is filled in the hollow portion of the positive electrode and contains a negative electrode active material containing zinc, A separator is disposed between the positive electrode and the negative electrode, The alkaline electrolyte contained in the positive electrode, the negative electrode, and the separator, The case comprises a sealing unit that covers the opening of the case, The sealing unit comprises a negative electrode current collector and a gasket. A portion of the negative electrode current collector is inserted into the gasket and also inserted into the negative electrode. The open end of the case of the separator extends beyond the open end face of the case at the positive and negative electrodes to a position where it contacts the gasket. A gap is formed between the negative electrode, the negative electrode current collector, the gasket, and the separator. The aforementioned gap is filled with an additive. The aforementioned additive contains a wax component having a melting point of 60°C or higher and 110°C or lower. The wax component comprises at least one selected from the group consisting of aliphatic hydrocarbon compounds and ester compounds. Alkaline batteries.

2. The aliphatic hydrocarbon compound includes a linear saturated aliphatic hydrocarbon compound. The alkaline battery according to claim 1.

3. The alkaline dry cell according to claim 1 or 2, wherein the ester compound comprises a fatty acid ester compound.

4. The endothermic onset temperature in differential scanning calorimetry of the wax component is 50°C or higher and 85°C or lower. The alkaline battery according to claim 1 or 2.

5. The wax component contains 10 mg to 200 mg per gram of zinc derived from the negative electrode active material. The alkaline battery according to claim 1 or 2.

6. A cylindrical case with a bottom, A hollow cylindrical positive electrode is inscribed within the aforementioned case, The negative electrode is filled in the hollow portion of the positive electrode and contains a negative electrode active material containing zinc, A separator is disposed between the positive electrode and the negative electrode, The alkaline electrolyte contained in the positive electrode, the negative electrode, and the separator, The case comprises a sealing unit that covers the opening of the case, The sealing unit comprises a negative electrode current collector and a gasket. A portion of the negative electrode current collector is inserted into the gasket and also inserted into the negative electrode. The open end of the case of the separator extends beyond the open end face of the case at the positive and negative electrodes to a position where it contacts the gasket. A gap is formed between the negative electrode, the negative electrode current collector, the gasket, and the separator. The aforementioned gap is filled with an additive. The additive contains a wax component whose endothermic onset temperature in differential scanning calorimetry is 50°C or higher and 85°C or lower. The wax component comprises at least one selected from the group consisting of aliphatic hydrocarbon compounds and ester compounds. Alkaline batteries.

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