Alkaline batteries

Abstract

This alkaline dry battery comprises: a bottomed cylindrical case having a cylindrical side part and a bottom part provided with a positive electrode terminal part; a hollow cylindrical positive electrode that touches the inside of the case; a negative electrode that is filled in a hollow section of the positive electrode and that contains a negative-electrode active material containing zinc; a separator disposed between the positive electrode and the negative electrode; an alkaline electrolytic solution; and a sealing unit. The alkaline electrolytic solution is included in the positive electrode, the negative electrode, and the separator. The sealing unit is provided with a negative electrode terminal part, and covers an opening of the case. A gap between the negative electrode and the sealing unit and / or a gap between the negative electrode and the bottom part of the case is filled with an additive. The additive contains a polyethylene glycol compound having a melting point of 46°C or greater.

Description

Technical Field

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

Background Art

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

[0003] Patent Document 1 discloses that in an alkaline zinc-manganese dioxide battery containing mercury, polyethylene glycol having an average molecular weight in the range of about 190 to 7000 is included in the battery (anode gel or separator) in order to suppress the hydrogen generation reaction due to the contact between zinc and the electrolyte.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Regarding alkaline dry batteries, it is required to suppress the temperature rise during external short circuit and further improve safety.

Means for Solving the Problems

[0006] One aspect of the present disclosure relates to an alkaline dry cell comprising: a bottomed cylindrical case having a bottom portion with a positive electrode terminal and a cylindrical side portion; a hollow cylindrical positive electrode inscribed within the case; a negative electrode filled in the hollow portion of the positive electrode and containing a negative electrode active material containing zinc; 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 covering the opening of the case and having a negative electrode terminal, wherein an additive is filled in the gap between the negative electrode and the sealing unit, and / or the gap between the negative electrode and the bottom portion, and the additive contains a polyethylene glycol compound having a melting point of 46°C or higher. [Effects of the Invention]

[0007] According to this disclosure, it is possible to suppress the temperature rise when an alkaline battery is short-circuited externally.

[0008] 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, along with other objects and features of the present invention. [Brief explanation of the drawing]

[0009] [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 an alkaline battery in another embodiment of the present disclosure. [Modes for carrying out the invention]

[0010] The embodiments relating to 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.

[0011] An alkaline dry cell according to the 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 case has a bottom portion with a positive electrode terminal and cylindrical side portions. The negative electrode contains a negative electrode active material containing zinc. The sealing unit includes a negative electrode terminal. The alkaline electrolyte is contained in the positive electrode, negative electrode, and separator. An additive is filled in the gap between the negative electrode and the sealing unit, and / or the gap between the negative electrode and the bottom of the case. The additive includes a polyethylene glycol compound (hereinafter also referred to as "compound A") with a melting point of 46°C or higher. The positive electrode terminal and the negative electrode terminal may together be referred to as the "electrode terminal portion."

[0012] The melting point mentioned above refers to the value measured using a general method described in, for example, the Japanese Industrial Standard (JIS K 0064).

[0013] When the battery temperature rises due to an external short circuit, compound A begins to melt. As compound A melts, the heat generated by the external short circuit is absorbed. This suppresses the temperature rise during an external short circuit. Since the area near the electrode terminals tends to heat up easily during an external short circuit, filling the gap near the electrode terminals with compound A effectively suppresses the temperature rise during an external short circuit. The gap can be filled with the amount of compound A necessary to suppress the temperature rise during an external short circuit.

[0014] If an additive is filled in either the gap between the negative electrode and the sealing unit (the gap near the negative electrode terminal) or the gap between the negative electrode and the bottom of the case (the gap near the positive electrode terminal), a temperature rise suppression effect during an external short circuit can be obtained. From the viewpoint of obtaining a more significant temperature rise suppression effect during an external short circuit, it is desirable that the additive be filled in both the gap between the negative electrode and the sealing unit and the gap between the negative electrode and the bottom of the case.

[0015] If compound A is dispersed within the negative electrode, it will be located relatively far from the electrode terminals. As a result, the heat-absorbing effect of compound A due to its melting may not be fully effective in counteracting the heat generated at the electrode terminals during an external short circuit. Furthermore, this would be disadvantageous in terms of discharge performance.

[0016] Compound A, which has a melting point of 46°C or higher, exists as a solid during normal use (storage) of the battery and begins to melt when an external short circuit occurs. While compound A exists as a solid within the battery, its diffusion into the negative electrode is suppressed, and the filling of compound A does not affect the discharge performance. The melting point of compound A may also be 50°C or higher. From the viewpoint of battery safety and reliability, the melting point of compound A may be 46°C or higher (or 50°C or higher) and 90°C or lower, or 46°C or higher (or 50°C or higher) and 85°C or lower.

[0017] If the melting point of the polyethylene glycol compound is below 46°C, the polyethylene glycol compound may not melt sufficiently during an external short circuit, and the endothermic effect due to the melting of the polyethylene glycol compound may not be fully exerted to counteract the heat generated at the electrode terminals during an external short circuit.

[0018] Compound A is a polymer having an ethylene oxide skeleton and includes polyethylene glycol and its derivatives. In the derivatives of polyethylene glycol, the hydrogen atoms of the ethylene oxide (CH2CH2O) skeleton may be substituted with other substituents. Examples of the substituents include halogen atoms, methyl groups, ethyl groups, hydroxyl groups, etc.

[0019] The average molecular weight of Compound A may be 7300 or more and 100000 or less, and may also be 7300 or more and 30000 or less. In this specification, the average molecular weight of Compound A means the "number average molecular weight". The average molecular weight is determined by gel permeation chromatography (GPC).

[0020] Specific examples of the polyethylene glycol compound having a melting point of 46°C or higher include the product named "PEG6000" (melting point 56 - 61°C, average molecular weight 7300 - 9300) manufactured by Kishida Chemical Co., Ltd., the product named "PEG2000" (melting point 49 - 53°C, average molecular weight 1800 - 2200) manufactured by Kishida Chemical Co., Ltd., the product named "PEG4000" (melting point 53 - 57°C, average molecular weight 2700 - 3400) manufactured by Kishida Chemical Co., Ltd., the product named "PEG20000" (melting point 56 - 64°C, average molecular weight 18000 - 25000) manufactured by Kishida Chemical Co., Ltd., etc.

[0021] The amount of Compound A filled in a predetermined gap in the battery may be 1 mg or more and 200 mg or less, 50 mg or more and 200 mg or less, or 100 mg or more and 200 mg or less per 1 g of zinc derived from the negative electrode active material. If the amount of Compound A is within the above range, it is easy to fill Compound A in a predetermined gap in the battery, and it is easy to obtain the effect of suppressing the temperature rise during external short - circuit by Compound A.

[0022] The additive contains at least Compound A. That is, only Compound A may be filled into a predetermined gap as the additive. The additive may contain other components in addition to Compound A. The other component may be a component that enhances the binding force of solid Compound A (for example, polytetrafluoroethylene), and may be used by mixing it with powdery Compound A. The additive filled into a predetermined gap in the battery may be in the form of powder, pellet, or welded material. The pellet can be obtained, for example, by compression molding powdery Compound A or a mixture of powdery Compound A and other components. The welded material can be obtained, for example, by heating Compound A to a temperature above its melting point and welding it to the root part of a gasket or a negative electrode current collector (the part exposed in the gap between the negative electrode and the sealing unit).

[0023] Also, from the viewpoint of suppressing the diffusion of the additive into the negative electrode and suppressing the infiltration of the electrolyte into the additive, a thin film for partial shielding (for example, cellophane) may be disposed between the negative electrode and the additive.

[0024] Hereinafter, the alkaline dry battery according to the present embodiment will be described in detail with reference to the drawings. Note that the present disclosure is not limited to the following embodiments. Also, modifications can be made as appropriate without departing from the scope in which the effects of the present disclosure are achieved. Furthermore, combinations with other embodiments are also possible.

[0025] FIG. 1 is a front view of a horizontal half of an alkaline dry battery in an embodiment of the present disclosure, taken in cross section. FIG. 2 is a front view of a horizontal half of an alkaline dry battery in another embodiment of the present disclosure, taken in cross section. FIGS. 1 and 2 show examples of cylindrical batteries having an inside-out type structure. In FIG. 2, the same components as those in FIG. 1 are denoted by the same reference numerals.

[0026] 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.

[0027] 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.

[0028] 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. A portion of 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.

[0029] The open end of case 1 is crimped to the flange portion of the peripheral edge of the negative terminal plate 7 via the outer edge of the gasket 5. The outer surface of case 1 is covered with an outer label 8.

[0030] In the alkaline battery according to this embodiment, an additive 10 containing compound A 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 negative electrode current collector 6 (the portion exposed from the negative electrode 3), and the gasket 5). 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.

[0031] Because the additive 10 is filled in the gap near the negative electrode terminal plate 7, the heat-absorbing effect of compound A contained in the additive 20 during melting is efficiently exerted against the heat generated near the negative electrode terminal plate 7 during an external short circuit. The additive 10 can be filled as a ring-shaped pellet containing compound A. 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 placed 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 does not easily seep into the additive 10.

[0032] Furthermore, as shown in Figure 2, the gap between the gel-like negative electrode 3 and the bottom of the case 1 (the void formed by the convex portion 1a, which is the positive electrode terminal) may be filled with an additive 20 containing compound A. By filling the additive 20 adjacent to the bottom of the case 1, the endothermic effect of compound A contained in the additive 20 during melting is efficiently exerted against the heat generated near the bottom of the case 1 during an external short circuit. The additive 20 may be in powder or pellet form. Since the bottom paper 4b is interposed between the additive 20 and the negative electrode 3, the diffusion of the additive to the negative electrode is suppressed. Since the bottom paper 4 adjacent to the additive 20 holds the electrolyte, the electrolyte does not easily seep into the additive 20.

[0033] Additive 20 shown in Figure 2 may be packed together with additive 10 shown in Figure 1. 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 and / or between the gel-like negative electrode 3 and the additive 20 (at the position of the bottom paper 4b).

[0034] 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 2 It may also be in a range of less than / g.

[0035] In this specification, the average particle size is the 50% cumulative value (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.

[0036] 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, artificial graphite, etc., 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] [Examples] The present disclosure will be described in detail below based on examples and comparative examples, but the present disclosure is not limited to the following examples.

[0045] Examples 1-4 A cylindrical alkaline battery (LR6) of AA size, as shown in Figure 1, was fabricated using the following procedure.

[0046] (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.

[0047] Flake-shaped positive electrode mixture was crushed into granules, which were then classified using a sieve with a mesh size of 10 to 100. The resulting granules were then pressure-molded into a predetermined hollow cylindrical shape to produce two positive electrode pellets.

[0048] (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.

[0049] (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.

[0050] 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 polyethylene glycol compound were used. The polyethylene glycol compound used was "PEG6000," a product of Kishida Chemical Co., Ltd. The amount of polyethylene glycol compound filled (amount per 1g of zinc derived from the negative electrode active material) was as shown in Table 1.

[0051] 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.

[0052] 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.

[0053] 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 opening 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 with the additive filled in the gap between the negative electrode and the sealing unit. In Table 1, A1 to A4 are the batteries of Examples 1 to 4.

[0054] Examples 5-6 Instead of filling with additive 10, powdered polyethylene glycol compound was filled as additive 20 into the recess at the bottom of the case. Except as described above, batteries A5 to A6 (shown in Figure 2) of Examples 5 to 6 were prepared in the same manner as batteries A1 and A3 of Examples 1 and 3, respectively.

[0055] Example 7 In addition to additive 10, powdered polyethylene glycol compound was filled into the recess at the bottom of the case as additive 20. Except as described above, battery A7 of Example 7 (a battery in which additive 20 shown in Figure 2 was filled into the battery shown in Figure 1) was prepared in the same manner as battery A2 of Example 2. The same polyethylene glycol compound used for additive 20 as for additive 10 was used. The amount of polyethylene glycol compound filled for additive 20 was as shown in Table 1.

[0056] Example 8 The additive 10 was filled by heating the polyethylene glycol compound to 70°C and welding it to the base of the negative electrode current collector (the part of the negative electrode current collector that is exposed in the gap between the sealing unit and the negative electrode). Except as described above, battery A8 of Example 8 (the battery shown in Figure 1) was manufactured in the same manner as battery A3 of Example 3.

[0057] Example 9 The gap between the negative electrode and the sealing unit was filled with additive 10, product name "PEG2000" manufactured by Kishida Chemical Co., Ltd. Except as described above, battery A9 of Example 9 (shown in Figure 1) was prepared in the same manner as battery A3 of Example 3.

[0058] Example 10 The gap between the negative electrode and the sealing unit was filled with additive 10, product name "PEG20000" manufactured by Kishida Chemical Co., Ltd. Except as described above, battery A10 of Example 10 (shown in Figure 1) was prepared in the same manner as battery A3 of Example 3.

[0059] Comparative Example 1 Comparative Example 1's battery X1 was prepared in the same manner as battery A1 of Example 1, except that the gap between the negative electrode and the sealing unit was not filled with an additive (polyethylene glycol compound).

[0060] Comparative Example 2 The amount of polyethylene glycol compound used was as shown in Table 1. The polyethylene glycol compound used was "PEG600" (melting point: 18-22°C, average molecular weight: 570-630), manufactured by Kishida Chemical Co., Ltd. Except as described above, battery X2 of Comparative Example 2 was prepared in the same manner as battery A5 of Example 5.

[0061] Comparative Example 3 The amount of polyethylene glycol compound used was as shown in Table 1. The polyethylene glycol compound used was "PEG1000" (melting point: 35-39°C, average molecular weight: 950-1050) manufactured by Kishida Chemical Co., Ltd. Except as described above, battery X3 of Comparative Example 3 was prepared in the same manner as battery A5 of Example 5.

[0062] Comparative Example 4 The gap between the negative electrode and the sealing unit was not filled with an additive (polyethylene glycol compound). In the preparation of the negative electrode, an additive (polyethylene glycol compound) was added to the gel-like negative electrode and dispersed the additive within the negative electrode. Except as described above, battery X4 of Comparative Example 4 was prepared in the same manner as battery A2 of Example 2.

[0063] [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.

[0064] The evaluation results are shown in Table 1. Note that the filling amount in Table 1 represents the amount (mg) of polyethylene glycol compound filled per gram of zinc derived from the negative electrode active material contained in the negative electrode.

[0065] [Table 1]

[0066] In batteries A1 to A10, which were filled with polyethylene glycol compounds having a melting point of 46°C or higher in predetermined gaps, the temperature rise during external short circuits was suppressed more than in batteries X1 to X4. In batteries A1 to A10, a predetermined amount of polyethylene glycol compound was filled in the gaps near the electrode terminals, and the endothermic effect of the compound upon melting was efficiently exerted against the heat generated at the electrode terminals during external short circuits.

[0067] In battery X1, the battery temperature rose during an external short circuit because no additive was filled. In batteries X2 and X3, the rise in battery temperature during an external short circuit could not be suppressed because a polyethylene glycol compound with a melting point of less than 46°C was filled. In battery X4, the polyethylene glycol compound was dispersed inside the negative electrode, so the compound was located away from the electrode terminals, and the endothermic effect of the compound when it melted was not sufficiently exerted against the heat generated at the electrode terminals during an external short circuit, thus failing to suppress the rise in battery temperature. Battery X4 is also at a disadvantage in terms of discharge performance. [Industrial applicability]

[0068] 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.

[0069] 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]

[0070] 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, 20: Additives

Claims

1. A bottomed cylindrical case having a bottom portion with a positive terminal and a cylindrical side portion, 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, A sealing unit that covers the opening of the aforementioned case and includes a negative terminal portion, It is equipped with, The gap between the negative electrode and the sealing unit, and / or the gap between the negative electrode and the bottom, is filled with an additive. The aforementioned additive is an alkaline dry cell containing a polyethylene glycol compound with a melting point of 46°C or higher.

2. The alkaline dry cell according to claim 1, wherein the average molecular weight of the polyethylene glycol compound is 7,300 or more and 100,000 or less.

3. The alkaline dry cell according to claim 1 or 2, wherein the polyethylene glycol compound is contained in an amount of 1 mg to 200 mg per gram of zinc derived from the negative electrode active material.

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