Alkaline dry battery

Abstract

This alkaline dry battery comprises a positive electrode, a negative electrode, a separator, and an electrolytic solution. The negative electrode contains zinc alloy particles as a negative electrode active material. The electrolytic solution contains a linear aliphatic secondary amine as an additive. The number of carbon atoms included in the linear aliphatic secondary amine is in the range of 3-13.

Description

Alkaline batteries Cross-reference of related applications

[0001] This disclosure claims priority rights to Japanese Patent Application No. 2024-171093, filed with the Japan Patent Office on 30 September 2024, and the entirety of the said patent application is incorporated herein by reference.

[0002] This disclosure relates to alkaline batteries.

[0003] Alkaline dry cell batteries (alkaline manganese dry cell batteries) are widely used because they have a larger battery capacity and can deliver a larger current than manganese dry cell batteries. An alkaline dry cell consists of a positive electrode, a negative electrode, a separator placed between the positive and negative electrodes, and an alkaline electrolyte. Various proposals have been made to improve the characteristics of alkaline dry cell batteries.

[0004] Patent Document 1 proposes "a method for producing a zinc-alkaline battery, characterized in that, in preparing a gel-like negative electrode by mixing and dispersing zinc alloy powder in a gel-like alkaline electrolyte, a zinc alloy containing at least one of the group consisting of indium, lead, bismuth, calcium, aluminum, and lithium, and free of mercury, is used as the active material, and an aromatic amine is included in the alkaline electrolyte."

[0005] Japanese Patent Application Publication No. 5-242895

[0006] Alkaline batteries are expected to require further improvements in reliability to withstand use under a variety of conditions.

[0007] One aspect of this disclosure relates to an alkaline dry cell comprising a positive electrode, a negative electrode, a separator, and an electrolyte, wherein the negative electrode comprises zinc alloy particles as a negative electrode active material, and the electrolyte comprises a linear aliphatic secondary amine, the number of carbon atoms in the linear aliphatic secondary amine being in the range of 3 to 13.

[0008] According to this disclosure, a highly reliable alkaline battery can be obtained.

[0009] This is a schematic partially exploded cross-sectional view showing an example of an alkaline dry cell according to the embodiments of this disclosure.

[0010] Novel features of the present invention are described in the appended claims, but the present invention, both in terms of structure and content, and in conjunction with other objects and features of the present invention, will be better understood by the following detailed description in conjunction with the drawings.

[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 other materials may be applied as long as they allow the invention of this disclosure to be carried out. 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 the given lower limit and either the given upper limit may be arbitrarily combined, as long as the lower limit does not exceed the upper limit. In the following description, when examples of components or methods are listed, unless otherwise specified, only one of the listed examples may be used, or multiple of the listed examples may be used in combination.

[0012] (Alkaline Battery) The alkaline battery according to this embodiment may be referred to as "alkaline battery (AB)" below. The alkaline battery (AB) includes a positive electrode, a negative electrode, a separator, and an electrolyte. The negative electrode contains zinc alloy particles as the negative electrode active material. The electrolyte contains a chain-like aliphatic secondary amine as an additive. The number of carbon atoms in the chain-like aliphatic secondary amine is in the range of 3 to 13. Such a chain-like aliphatic secondary amine may be referred to as "secondary amine (A)" below.

[0013] During over-discharge of alkaline batteries, excessive dissolution of the zinc alloy (negative electrode active material) in the negative electrode causes cracks to form on the surface of the zinc alloy, creating a new surface. It is believed that protons in the electrolyte come into contact with this new surface and are reduced, generating hydrogen gas.

[0014] Patent Document 1 proposes adding sulfanilic acid to a battery to suppress gas generation. However, sulfanilic acid has a primary amino group (-NH ２Because it has a ) structure, it has a strong adsorption force to the surface of zinc alloys. Also, sulfanilic acid has a bulky aromatic ring and a sulfo group in its molecule. Therefore, during over-discharge, it can suppress contact of protons in the electrolyte with the newly formed surface, but during normal discharge, it inhibits the dissolution reaction of zinc, reducing discharge performance.

[0015] In the alkaline dry cell (AB) according to this disclosure, a secondary amine (A) is used as an additive to the electrolyte. The secondary amine (A) is thought to repeatedly adsorb to and desorb from the surface of the zinc alloy. The secondary amine (A) does not have a very strong adsorption force to the surface of the zinc alloy. Therefore, there is always a surface that is not covered by the secondary amine (A) and where the zinc dissolution reaction can occur. In addition, the secondary amine (A) has only flexible and mobile chain-like aliphatic groups, and the number of carbon atoms contained in the molecule is limited to the range of 3 to 13. Therefore, the zinc dissolution reaction is hardly inhibited. For these reasons, it is thought that by using a secondary amine (A), hydrogen gas generation during over-discharge can be effectively suppressed while maintaining discharge performance.

[0016] When the number of carbon atoms in the molecule of secondary amine (A) is less than 3, the effect of suppressing hydrogen gas generation during over-discharge decreases. This is thought to be because the molecular size of secondary amine (A) is small, so the surface of the zinc alloy is not sufficiently coated by secondary amine (A). When the number of carbon atoms in the molecule of secondary amine (A) exceeds 13, the discharge performance during normal discharge decreases. This is thought to be because the molecular size of secondary amine (A) is large, so the dissolution reaction of zinc is inhibited.

[0017] From the viewpoint of improving the balance between discharge performance and hydrogen gas generation suppression, the number of carbon atoms in the molecule of secondary amine (A) is preferably in the range of 6 to 11, more preferably in the range of 7 to 10, and even more preferably in the range of 8 to 10.

[0018] From the viewpoint of limiting the molecular size of the secondary amine (A) to a size suitable for balancing discharge performance and hydrogen gas generation suppression, it is preferable that the number of nitrogen atoms contained in the secondary amine (A) is 1 or 2, and the secondary amine (A) may have only one nitrogen atom.

[0019] The secondary amine (A) may be any linear aliphatic amine, and may have only a straight chain or a branched chain. In particular, the secondary amine (A) is preferably a flexible and mobile linear aliphatic secondary amine.

[0020] A preferred example of a secondary amine (A) is a secondary amine (A) having only one nitrogen atom to which two linear alkyl groups are bonded. Since linear alkyl groups have a higher density per unit molecular volume than branched alkyl groups, the surface area on which secondary amine (A) can be adsorbed on the zinc alloy surface increases, and the coverage rate increases significantly.

[0021] Examples of linear alkyl groups include methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, and n-nonyl group.

[0022] Examples of branched alkyl groups include 3-methylbutyl group, 4-methylpentyl group, 4-methylhexyl group, 5-methylhexyl group, and 2-ethylhexyl group.

[0023] Specific examples of secondary amines (A) include N-ethylmethylamine, N-ethylheptylamine, N-dodecylmethylamine, and N,N-diisopentylamine. Among these, alkaline dry cell batteries (AB) with N-ethylheptylamine added to the electrolyte offer an excellent balance between discharge performance and hydrogen gas generation suppression.

[0024] The ratio (Wa / Wz) of the mass Wa of the secondary amine (A) contained in the electrolyte to the mass Wz of the zinc alloy particles in the negative electrode is, for example, 50 ppm (50 × 10⁻¹⁶). －６) or more, 100 ppm or more, or 500 ppm or more, and may be 2500 ppm or less, 2000 ppm or less, 1500 ppm or less, 1000 ppm or less, or 800 ppm or less. The mass Wz of zinc alloy particles is the sum of the masses of all zinc alloy particles contained in the negative electrode. The mass Wa of secondary amine (A) is the sum of the masses of all secondary amine (A) in the electrolyte present in the battery housing. Note that the mass of secondary amine (A) adsorbed on zinc alloy particles is also included in the mass Wa as secondary amine (A) in the electrolyte. The ratio Wa / Wz is 100 ppm (100 × 10⁻⁶). －６ It may be between 0.50 ppm and 2000 ppm, or it may be in the range of 100 ppm to 1000 ppm (for example, the range of 500 ppm to 1000 ppm).

[0025] The alkaline battery (AB) according to this disclosure comprises a positive electrode, a negative electrode, a separator, and an electrolyte, and optionally includes other components. Components other than the secondary amine (A) may be those used in known alkaline batteries. Examples of components of the alkaline battery (AB) other than the secondary amine (A) are described below, but the components of the alkaline battery (AB) are not limited to these examples.

[0026] (Positive Electrode) The positive electrode comprises a positive electrode active material and optionally further comprises other additives (such as binders and conductive materials). The positive electrode can be formed by pressurizing a positive electrode mixture into a cylindrical body (positive electrode pellet). The positive electrode mixture comprises, for example, a positive electrode active material, a conductive material, and an alkaline electrolyte, and optionally further comprises a binder. The positive electrode pellet may be pressurized after being placed in a battery case so as to adhere tightly to the wall of the battery case. The alkaline electrolyte used to manufacture the positive electrode may or may not contain the secondary amine (A) described above.

[0027] Manganese dioxide can be used as the positive electrode active material. A preferred example of manganese dioxide is electrolytic manganese dioxide, but natural manganese dioxide or chemical manganese dioxide may also be used. Examples of manganese dioxide crystal structures include α-type, β-type, γ-type, δ-type, ε-type, η-type, λ-type, and ramsdellite-type.

[0028] The average particle size (D50) of the manganese dioxide powder may be in the range of 25 μm to 60 μm in terms of facilitating the ensuring of the filling property of the positive electrode and the diffusibility of the electrolyte within the positive electrode. In this specification, the average particle size refers to the median diameter (D50) at which the cumulative volume becomes 50% in the volume-based particle size distribution. The median diameter can be determined, for example, using a laser diffraction / scattering type particle size distribution measuring device.

[0029] From the viewpoints of formability and suppression of the expansion of the positive electrode, the BET specific surface area of the manganese dioxide may be, for example, in the range of 20 m 2 / g to 50 m 2 / g. The BET specific surface area can be measured, for example, by using a specific surface area measuring device based on the nitrogen adsorption method.

[0030] The conductive material may be a conductive carbon material. Examples of the conductive carbon material include carbon black (such as acetylene black), graphite, etc. Examples of graphite include natural graphite, artificial graphite, etc. The conductive material may be in powder form. The average particle size (D50) of the conductive material may be in the range of 3 μm to 20 μm. The content of the conductive material in the positive electrode may be in the range of 3 parts by mass to 10 parts by mass (for example, in the range of 5 parts by mass to 9 parts by mass) with respect to 100 parts by mass of the manganese dioxide.

[0031] [[ID=:13]] In order to absorb hydrogen generated inside the battery, a silver compound may be added to the positive electrode. Examples of the silver compound include silver oxide (Ag ２ O, AgO, Ag ２ O ３ etc.), silver nickel composite oxide (AgNiO ２ ), etc.

[0032] (Negative electrode) The negative electrode contains zinc alloy particles (zinc alloy powder) as the negative electrode active material. The zinc alloy may contain at least one selected from the group consisting of indium, bismuth, and aluminum, from the viewpoint of corrosion resistance. The indium content in the zinc alloy may be in the range of, for example, 0.01% by mass to 0.1% by mass. The bismuth content in the zinc alloy may be in the range of, for example, 0.003% by mass to 0.02% by mass. The aluminum content in the zinc alloy may be in the range of, for example, 0.001% by mass to 0.03% by mass. The content of elements other than zinc in the zinc alloy may be in the range of 0.025% by mass to 0.08% by mass, from the viewpoint of corrosion resistance.

[0033] The average particle size (D50) of the zinc alloy powder may be in the range of 100 μm to 200 μm (for example, 110 μm to 160 μm) from the viewpoint of packing the negative electrode and the diffusibility of the electrolyte within the negative electrode.

[0034] The negative electrode may be a gel-type negative electrode. A gel-type negative electrode can be prepared, for example, by mixing negative electrode active material particles, a gelling agent, and an alkaline electrolyte.

[0035] As the gelling agent, known gelling agents used in the field of alkaline dry cell batteries may be used. For example, superabsorbent polymers may be used as gelling agents. Examples of gelling agents include polyacrylic acid and sodium polyacrylate. The amount of gelling agent may be in the range of 0.5 parts by mass to 2.5 parts by mass per 100 parts by mass of negative electrode active material.

[0036] To enhance the reaction efficiency of the negative electrode active material surface, additives such as surfactants may be added. Examples of surfactants include polyoxyalkylene group-containing compounds and phosphate esters. From the viewpoint of more uniformly dispersing the additives in the negative electrode, it is preferable to add the additives to the alkaline electrolyte used to prepare the negative electrode beforehand. The above-mentioned secondary amine (A) may or may not be added to the alkaline electrolyte used to prepare the negative electrode.

[0037] For the negative electrode, in order to improve corrosion resistance, a compound containing a metal with a high hydrogen overvoltage such as indium or bismuth may be appropriately added.

[0038] (Negative electrode current collector) An alkaline dry battery (AB) may include a negative electrode current collector inserted into the negative electrode. The material of the negative electrode current collector may be a metal (a single metal or an alloy). The material of the negative electrode current collector preferably contains copper and may be an alloy containing copper and zinc (for example, brass). The negative electrode current collector may be subjected to a plating treatment such as tin plating as required.

[0039] (Separator) The separator prevents a short circuit between the positive electrode and the negative electrode. A porous sheet having insulating properties can be used as the separator. For example, a non-woven fabric mainly composed of fibers or a microporous film made of resin can be used as the separator. Examples of the fiber material include cellulose, rayon, polyvinyl alcohol, etc. The non-woven fabric may be formed by co-papering cellulose fibers and polyvinyl alcohol fibers, or may be formed by co-papering rayon fibers and polyvinyl alcohol fibers. Examples of the material of the microporous film include resins such as cellophane and polyolefin. The thickness of the separator may be in the range of 200 μm to 300 μm. The separator may be formed by stacking a plurality of porous sheets. Also, the separator may be formed by winding a single porous sheet two or more times (for example, twice).

[0040] (Electrolyte) As the electrolyte (alkaline electrolyte), for example, an alkaline aqueous solution containing potassium hydroxide is used. The concentration of potassium hydroxide in the alkaline electrolyte is preferably in the range of 30 to 50% by mass (for example, in the range of 30 to 40% by mass). The alkaline electrolyte may contain lithium hydroxide (LiOH), sodium hydroxide (NaOH), cesium hydroxide (CsOH), rubidium hydroxide (RbOH), etc.

[0041] As described above, a secondary amine (A) is added to the electrolytic solution. The secondary amine (A) can be added to the electrolytic solution by dissolving it in the electrolytic solution. The electrolytic solution may contain additives (such as surfactants) other than the secondary amine (A). By using a surfactant, the dispersibility of the negative electrode active material particles can be enhanced. As the surfactant, those exemplified for the negative electrode can be used. The content of the surfactant in the alkaline electrolytic solution is usually in the range of 0 to 0.5% by mass (for example, in the range of 0 to 0.2% by mass).

[0042] (Battery housing) The battery housing is composed of a battery case, a negative electrode terminal plate that seals the opening of the battery case, and a gasket. The battery case has a bottomed cylindrical shape. The negative electrode terminal plate has a generally disc-shaped shape. For the metal case, for example, a nickel-plated steel sheet is used. In order to reduce the contact resistance between the positive electrode and the battery case, the inner surface of the battery case may be coated with a carbon film. The negative electrode terminal plate can be formed of the same material as the metal case, for example, a nickel-plated steel sheet. The negative electrode terminal plate functions as a negative electrode terminal. The battery case functions as a positive electrode terminal.

[0043] Examples of the gasket material include polyamide, polyethylene, polypropylene, polyphenyl ether, polyphenylene ether, etc. From the viewpoint of corrosion resistance to the alkaline electrolytic solution, the gasket material is preferably polyamide-6,6, polyamide-6,10, polyamide-6,12, and polypropylene.

[0044] (Manufacturing method of alkaline dry battery (AB)) The manufacturing method of the alkaline dry battery (AB) is not particularly limited. Except for adding the secondary amine (A) to the electrolytic solution, the alkaline dry battery (AB) may be manufactured by a known method. For example, the alkaline dry battery (AB) may be manufactured according to the procedure described in the examples below.

[0045] Hereinafter, an example of an embodiment relating to this disclosure will be specifically described with reference to the drawings. The components of the alkaline battery described below can be the components described above. Furthermore, the components of the alkaline battery described below can be modified based on the above description. In addition, the matters described below may be applied to the above embodiment.

[0046] (Embodiment 1) Figure 1 shows a partially exploded cross-sectional view of the alkaline battery 10 according to Embodiment 1. The alkaline battery 10 is a cylindrical battery having an inside-out structure. The alkaline battery 10 includes a battery case 1 and a positive electrode 2, a negative electrode (gel-like negative electrode) 3, a separator 4, a sealing unit 9, and an electrolyte, which are arranged inside the battery case 1. The electrolyte contains the secondary amine (A) described above.

[0047] The battery case 1 is a bottomed cylindrical case and functions as the positive electrode terminal. The positive electrode 2 has a cylindrical shape with a hollow section in the center. The positive electrode 2 is positioned in contact with the inner wall of the battery case 1. In the example shown in Figure 1, the positive electrode 2 is formed by stacking two cylindrical positive electrode pellets.

[0048] The separator 4 is composed of a cylindrical portion 4a and a bottom portion 4b that closes one end of the cylindrical portion. The cylindrical portion 4a is positioned along the inner surface of the hollow portion of the positive electrode 2 and separates the positive electrode 2 from the negative electrode 3. The bottom portion 4b is positioned at the bottom of the hollow portion of the positive electrode 2 and separates the negative electrode 3 from the battery case 1.

[0049] The opening of the battery case 1 is sealed by a sealing unit 9. The sealing unit 9 includes a gasket 5, a negative electrode current collector 6, and a negative electrode terminal plate 7. The negative electrode terminal plate 7 functions as a negative electrode terminal. The negative electrode current collector 6 has a nail shape with a head and a body. The negative electrode current collector 6 may be made of, for example, brass. The surface of the negative electrode current collector 6 may be plated, such as tin plating. The body of the negative electrode current collector 6 is inserted into a through hole provided in the center of the gasket 5 and is also inserted into the negative electrode 3. The head of the negative electrode current collector 6 is welded to the central flat portion of the negative electrode terminal plate 7.

[0050] The open end of the battery case 1 is crimped to the periphery (flange) of the negative electrode terminal plate 7 via the periphery of the gasket 5. Most of the outer surface of the battery case 1 is covered by the outer label 8. The battery case 1, gasket 5, and negative electrode terminal plate 7 constitute the battery housing. The positive electrode 2, negative electrode 3, separator 4, and electrolyte (not shown) are arranged inside the battery case 1. The gasket 5 in Figure 1 has an annular thin-walled portion 5a.

[0051] (Note) The following technologies are disclosed by the above description. (Technology 1) An alkaline dry cell comprising a positive electrode, a negative electrode, a separator, and an electrolyte, wherein the negative electrode comprises zinc alloy particles as a negative electrode active material, the electrolyte comprises a linear aliphatic secondary amine as an additive, and the number of carbon atoms in the linear aliphatic secondary amine is in the range of 3 to 13. (Technology 2) The alkaline dry cell according to Technology 1, wherein the number of nitrogen atoms in the linear aliphatic secondary amine is 1 or 2. (Technology 3) The alkaline dry cell according to Technology 1 or 2, wherein the linear aliphatic secondary amine has only one nitrogen atom, and two linear alkyl groups are bonded to the nitrogen atom. (Technology 4) The alkaline dry cell according to any one of Technology 1 to 3, wherein the linear aliphatic secondary amine comprises N-ethylheptylamine. (Technical 5) An alkaline dry cell according to any one of Technical 1 to 4, wherein the ratio (Wa / Wz) of the mass Wa of the chain-like aliphatic secondary amine contained in the electrolyte to the mass Wz of the zinc alloy particles is 100 ppm to 2000 ppm.

[0052] The alkaline dry cell of this disclosure will be described in more detail by reference to examples.

[0053] (Experiment 1) In Experiment 1, several alkaline dry cell batteries with different electrolytes were prepared and evaluated.

[0054] Batteries A1 to A9 were manufactured using the following procedures (1) to (4). (1) Preparation of the electrolyte (alkaline electrolyte) An alkaline aqueous solution containing potassium hydroxide (33% by mass), zinc oxide (2% by mass), and secondary amine (A) was prepared as the alkaline electrolyte. Compounds 1 to 4 below were used as secondary amine (A). The ratio of the mass Wa of secondary amine (A) contained in the electrolyte to the mass Wz of the negative electrode active material (zinc alloy particles) in the negative electrode (Wa / Wz) was set to the values ​​shown in Table 1.

[0055] (Compound 1) N-ethylheptylamine

[0056] (Compound 2) N-ethylmethylamine

[0057] (Compound 3) N-dodecylmethylamine

[0058] (Compound 4) N,N-diisopentylamine

[0059] (2) Preparation of the positive electrode A mixture was obtained by mixing manganese dioxide (positive electrode active material) and graphite (conductive material). These were mixed in a mass ratio of manganese dioxide:graphite = 100:6. For the manganese dioxide, electrolytic manganese dioxide powder (average particle size: 40 μm) was used. For the graphite, graphite powder (average particle size (D50): 8 μm) was used.

[0060] An electrolyte was added to the above mixture, and after thorough stirring, it was compressed into flakes to obtain a positive electrode mixture. The mass ratio of the mixture to the electrolyte was 100:1.5. The same electrolyte as the alkaline electrolyte prepared in (1) above was used, except that secondary amine (A) was not added.

[0061] Next, the flake-shaped positive electrode mixture was crushed into granules, which were then classified using a sieve with a mesh size of 10 to 100 to obtain granules. The obtained granules were then pressure-molded into a hollow cylindrical shape (height 10.8 mm) to obtain positive electrode pellets. Four of these positive electrode pellets were prepared.

[0062] (3) Preparation of the negative electrode A negative electrode was prepared by mixing the negative electrode active material, electrolyte, and gelling agent. The same electrolyte as the alkaline electrolyte prepared in (1) above was used, except that secondary amine (A) was not added. The negative electrode active material was zinc alloy particles (average particle size: 130 μm) containing 0.02 mass% indium, 0.01 mass% bismuth, and 0.005 mass% aluminum. The gelling agent was a mixture of crosslinked branched polyacrylic acid and highly crosslinked chain sodium polyacrylate. The mass ratio of the negative electrode active material, electrolyte, and gelling agent in the gel negative electrode was negative electrode active material:electrolyte:gelling agent = 100:50:1.

[0063] (4) Assembly of Battery A1 An alkaline dry cell was assembled using the above components in the following manner. The procedure for assembling the battery will be explained with reference to Figure 1. First, a bottomed cylindrical case made of nickel-plated steel sheet was coated with a coating agent (product name: Bunny Height) manufactured by Nippon Graphite Co., Ltd. to form a carbon film with a thickness of approximately 10 μm, thereby obtaining the battery case 1. Next, four positive electrode pellets were inserted vertically into the battery case 1, and then pressurized to form a positive electrode 2 that was in close contact with the inner wall of the battery case 1. Next, a separator 4 was placed inside the positive electrode 2. The separator 4 was made of a nonwoven fabric sheet mainly composed of rayon fibers and polyvinyl alcohol fibers. Next, the alkaline electrolyte prepared in (1) above was injected into the inside of the separator 4 and impregnated into the separator 4. This was left for a predetermined time to allow the alkaline electrolyte to permeate from the separator 4 to the positive electrode 2. After that, a gel-like negative electrode 3 was filled into the inside of the separator 4.

[0064] The negative electrode current collector 6 was formed by press-forming a general brass into a nail shape and then applying tin plating to the surface. 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. Subsequently, the body of the negative electrode current collector 6 was press-fitted into the through-hole in the center of the gasket 5, which is mainly composed of polyamide-6,12. In this way, a sealing unit 9 consisting of the gasket 5, the negative electrode current collector 6, and the negative electrode terminal plate 7 was manufactured.

[0065] Next, the sealing unit 9 was placed in the opening of the battery case 1. At this time, the body of the negative electrode current collector 6 was inserted into the negative electrode 3. Next, the opening end of the battery case 1 was crimped to the periphery of the negative electrode terminal plate 7 so as to sandwich the gasket 5, thereby sealing the opening of the battery case 1. In this way, the positive electrode 2, negative electrode 3, separator 4, and alkaline electrolyte were placed inside the battery housing.

[0066] Next, the outer surface of the battery case 1 was covered with the outer label 8. Batteries A1 to A9 (alkaline dry cell batteries) were manufactured in this manner.

[0067] (Batteries C1-C5) Batteries C1-C5 were manufactured using the same method and conditions as battery A1, except that the additives added to the electrolyte were changed to compounds 5-8 listed below, and the ratio of the mass Wa of the additives contained in the electrolyte to the mass Wz of the negative electrode active material (zinc alloy particles) in the negative electrode (ratio W / Wz) was changed as shown in Table 1. In the manufacture of battery C1, no additives were added to the electrolyte.

[0068] (Compound 5) Sulfanilic acid

[0069] (Compound 6) N,N-dicyclohexylamine

[0070] (Compound 7) N,N-dimethylamine

[0071] (Compound 8) N,N-Diheptylamine

[0072] (Battery Evaluation) <Hydrogen Gas Generation During Over-Discharge> Two batteries were connected in series, and a 10Ω resistor was also connected. Battery A1 was discharged until the total voltage of the two batteries dropped to 1.2V. Next, the 10Ω resistor was replaced with a 1Ω resistor, and the two batteries A1 were maintained in series for 36 hours. After that, a hole was made in one of the two batteries A1 that had reversed polarity due to over-discharge, and the hydrogen gas accumulated inside the battery was collected and its volume (hydrogen gas generation amount) was measured. The same evaluation was performed on the other batteries.

[0073] The measurement results are shown in Table 1. The hydrogen gas generation amount V in Table 1 is a relative value when the hydrogen gas generation amount of battery C1 is set to 100.

[0074] <Discharge Performance> The batteries were connected via a switch to a device capable of discharging at a constant current, and intermittent discharge was performed by keeping the switch ON for a duty cycle of 16 minutes per day. Specifically, under conditions of 20±1℃, a cycle of 2 minutes of discharge followed by a 58-minute pause was repeated eight times, followed by a 16-hour pause cycle. The above discharge cycle was repeated until the battery voltage reached 1.1V. For five alkaline dry cell batteries (N=5), the total discharge time from the start of discharge until the battery voltage fell below 1.1V (i.e., the total period during which the switch was ON) was evaluated as the discharge duration.

[0075] The measurement results are shown in Table 1. The discharge duration T in Table 1 is a relative value when the discharge duration of battery C1 is set to 100.

[0076]

[0077] Batteries A1 to A7 are alkaline dry cell batteries (AB) according to this disclosure. Batteries C1 to C5 are comparative examples. A smaller relative value for the amount of hydrogen gas generated V during over-discharge is preferable. A larger relative value for the discharge duration T is preferable.

[0078] As shown in Table 1, in batteries A1 to A7, the amount of hydrogen gas generated is reduced while sufficient discharge performance is ensured. The larger the ratio Wa / Wz, the greater the effect of suppressing hydrogen gas generation, but discharge performance decreases slightly above 2000 ppm. Compound 1 has the greatest effect in suppressing hydrogen gas generation.

[0079] In battery C4, which uses compound 7, a secondary amine (A) with 2 carbon atoms, no significant effect in suppressing hydrogen gas generation was observed, and the discharge performance was slightly reduced. In battery C5, which uses compound 8, a secondary amine (A) with 14 carbon atoms, no significant effect in suppressing hydrogen gas generation was observed, and the discharge performance was slightly reduced. It is thought that when the number of carbon atoms in secondary amine (A) reaches 14, the hydrocarbon groups are bonded together by intermolecular forces, reducing the molecular area necessary for hydrogen gas suppression, and thus the gas generation suppression ability cannot be exhibited.

[0080] In battery C2, which uses compound 5, a primary amine, and in battery C6, which uses compound 6, an aliphatic group having a cyclic structure, an effect of suppressing hydrogen gas generation is observed, but the discharge performance is reduced.

[0081] This disclosure can be used in alkaline batteries.

[0082] 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.

[0083] 2: Positive electrode 3: Negative electrode 4: Separator 5: Gasket 6: Negative electrode current collector 7: Negative electrode terminal plate 9: Sealing unit 10: Alkaline battery

Claims

1. An alkaline dry cell comprising a positive electrode, a negative electrode, a separator, and an electrolyte, wherein the negative electrode contains zinc alloy particles as a negative electrode active material, and the electrolyte contains a chain-like aliphatic secondary amine, the number of carbon atoms in the chain-like aliphatic secondary amine is in the range of 3 to 13.

2. The alkaline dry cell according to claim 1, wherein the number of nitrogen atoms contained in the chain-like aliphatic secondary amine is 1 or 2.

3. The alkaline dry cell according to claim 1, wherein the linear aliphatic secondary amine has only one nitrogen atom, and two linear alkyl groups are bonded to the nitrogen atom.

4. The alkaline battery according to claim 1, wherein the linear aliphatic secondary amine comprises N-ethylheptylamine.

5. The alkaline dry cell according to any one of claims 1 to 4, wherein the ratio (Wa / Wz) of the mass Wa of the chain-like aliphatic secondary amine contained in the electrolyte to the mass Wz of the zinc alloy particles is 100 ppm to 2000 ppm.

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