Alkaline battery and method for manufacturing alkaline battery

Abstract

An alkaline battery (1) in which a positive electrode (5), a negative electrode (7), a separator (6), and an electrolyte solution are accommodated in a container (8). And the electrolyte is a potassium hydroxide aqueous solution with the concentration of 40-50%. The negative electrode is configured from a gel-like negative electrode mixture containing a negative electrode active material and an aqueous alkaline solution. The alkaline aqueous solution contains potassium hydroxide and sodium hydroxide in a molar ratio ranging from 89: 11 to 96: 4. The positive electrode is composed of a positive electrode mixture containing a positive electrode active material containing silver oxide and manganese dioxide, and the blending ratio of manganese dioxide in the positive electrode mixture is 25-50 mass%.

Description

Technical Field

[0001] The present invention relates to an alkaline battery and a method for manufacturing the alkaline battery.

[0002] This application claims priority based on Japanese Patent Application No. 2022-182350 filed in Japan on November 15, 2022, and the contents are cited herein. Background Art

[0003] Silver oxide batteries, which use silver oxide as their positive electrode active material, are compact and have high capacity. These characteristics are being utilized in applications such as watches and calculators, and are now being used in medical devices. Silver oxide batteries undergo improvements based on various factors, such as cost and electrical properties, when being applied to new applications.

[0004] For example, Patent Document 1 below discloses a silver oxide battery for medical equipment used for a short period of time under heavy load conditions. Specifically, with the goal of improving heavy load characteristics, a technique for regulating the particle size of the negative electrode zinc (the proportion of particles passing 330 mesh) is disclosed. Furthermore, a technique for regulating the resistance of the separator (5 to 30 mΩ·(2.54 cm)) is also disclosed. 2 ), the closed-circuit voltage characteristics after 1 minute and 10 minutes under specified conditions can be obtained.

[0005] Furthermore, it is disclosed that the heavy-load characteristics can be improved by making the negative electrode non-gel to maintain a high ion transfer speed, and the battery capacity can be increased by increasing the proportion of zinc-based particles in the negative electrode.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Laid-Open No. 2006-252899. Summary of the Invention

[0009] Problems to be solved by the invention

[0010] As the positive electrode active material for alkaline batteries, it is considered to use manganese dioxide, a material cheaper than silver oxide, in combination with silver oxide. In this case, research is underway to reduce costs and facilitate application in new applications. To achieve the same electrical properties as the aforementioned silver oxide battery in such alkaline batteries, the efficiency of the electrode discharge reaction must be improved.

[0011] In addition, by adding silver oxide (7.143 g / cm 3 ) Small manganese dioxide (5.02g / cm 3), making it difficult to increase particle density. Therefore, in this case, the battery height tends to increase. However, solving this problem does not increase the amount of positive electrode that can be used, and there is also the problem of not being able to fully obtain the discharge capacity.

[0012] An object of the present invention is to provide an alkaline battery that has excellent discharge characteristics and can be reduced in cost.

[0013] Means of solving problems

[0014] (1) The alkaline battery according to the present invention is an alkaline battery comprising a positive electrode, a negative electrode, a separator, and an electrolyte contained in a container. The electrolyte is a potassium hydroxide aqueous solution having a concentration of 40 to 50%. The negative electrode is composed of a gel-like negative electrode mixture containing a negative electrode active material and an alkaline aqueous solution. The alkaline aqueous solution contains potassium hydroxide and sodium hydroxide in a molar ratio ranging from 89:11 to 96:4. The positive electrode is composed of a positive electrode mixture having a positive electrode active material containing silver oxide and manganese dioxide. The blending ratio of manganese dioxide in the positive electrode mixture is 50% by mass or less.

[0015] In this case, manganese dioxide is added at a preferred ratio of 50% by mass or less relative to the positive electrode mixture to achieve cost reduction, and a 40-50% concentration of potassium hydroxide aqueous solution is provided as the electrolyte. Furthermore, by setting the molar ratio of potassium hydroxide to sodium hydroxide in the gelled negative electrode as the electrolyte to a preferred ratio of 89:11 to 96:4, an alkaline battery with excellent discharge characteristics even under heavy load conditions can be provided.

[0016] (2) In the alkaline battery described in (1), the electrolyte may be a potassium hydroxide aqueous solution having a concentration of 44 to 50%.

[0017] When the electrolyte is a potassium hydroxide aqueous solution having a concentration of 44 to 50%, an alkaline battery having excellent discharge characteristics even under heavy load conditions can be reliably provided.

[0018] (3) In the alkaline battery according to (1) or (2), the blending ratio of manganese dioxide in the positive electrode mixture may be 25 to 44% by mass.

[0019] By setting the blending ratio of manganese dioxide to 25-44% by mass, the amount of expensive silver oxide used can be reduced, reliably achieving cost reduction. Furthermore, an alkaline battery having excellent discharge characteristics even under heavy load conditions can be provided.

[0020] (4) In the alkaline battery described in any one of (1) to (3), the resistance of the separator may be 250 mΩ·cm 2 the following.

[0021] By making the resistance of the separator 250 mΩ·cm 2 Hereinafter, an alkaline battery having excellent discharge characteristics even under heavy load conditions can be reliably obtained.

[0022] (5) In the alkaline battery according to any one of (1) to (4), the container may include a positive electrode can, a negative electrode can, and a gasket for sealing the positive electrode can and the negative electrode can.

[0023] In this case, a button-shaped alkaline battery comprising the positive electrode, negative electrode, separator, and electrolyte solution contained within a container consisting of a positive electrode can and a negative electrode can can be provided. This alkaline battery is low-cost and has excellent discharge characteristics even under heavy load conditions.

[0024] (6) The method for manufacturing an alkaline battery involved in the present invention is a method for manufacturing an alkaline battery in which a positive electrode, a negative electrode, a separator and an electrolyte are accommodated in a container, characterized in that: a negative electrode composed of a gel-like negative electrode mixture, the negative electrode mixture containing a mixed aqueous solution obtained by mixing a potassium hydroxide aqueous solution having a concentration of 45% and a sodium hydroxide aqueous solution having a concentration of 27% in a manner to achieve a mass ratio of 88:12 to 95:5 and a negative electrode active material; a positive electrode composed of a positive electrode mixture having a positive electrode active material containing silver oxide and manganese dioxide, wherein the mixing ratio of manganese dioxide in the positive electrode mixture is 50% by mass or less; and an electrolyte composed of a potassium hydroxide aqueous solution having a concentration of 40 to 50%; the positive electrode, the negative electrode, the separator and the electrolyte are accommodated in the container.

[0025] In this case, manganese dioxide is added to the positive electrode mixture at a preferred ratio of 50% by mass or less to achieve low costs, while a 40-50% concentration of potassium hydroxide aqueous solution is used as the electrolyte. Furthermore, the negative electrode electrolyte is a mixture of potassium hydroxide aqueous solution and sodium hydroxide aqueous solution at a mass ratio of 88:12 to 95:5. This allows the molar ratio of potassium hydroxide to sodium hydroxide in the negative electrode mixture to be adjusted to a preferred ratio of 89:11 to 96:4, enabling the manufacture of alkaline batteries with excellent discharge characteristics even under heavy load conditions.

[0026] Furthermore, by setting the amount of potassium hydroxide added to the negative electrode mixture to 95% by mass or less, the handling properties of the negative electrode mixture can be improved.

[0027] (7) In the alkaline battery described in (6), a potassium hydroxide aqueous solution having a concentration of 44 to 50% may be used as the electrolyte.

[0028] Since a potassium hydroxide aqueous solution with a concentration of 44 to 50% is used as the electrolyte, an alkaline battery with excellent discharge characteristics even under heavy load conditions can be reliably manufactured.

[0029] (8) In the alkaline battery described in (6) or (7), a positive electrode in which the blending ratio of the manganese dioxide is 25 to 44% by mass may be used as the positive electrode.

[0030] By setting the blending ratio of manganese dioxide to 25-44% by mass, the amount of expensive silver oxide used can be reduced, reliably achieving cost reduction. Furthermore, an alkaline battery with excellent discharge characteristics even under heavy load conditions can be produced.

[0031] (9) In the alkaline battery described in any one of (6) to (8), a battery having a resistance of 250 mΩ·cm can be used. 2 The following separators were used as the separators.

[0032] By using a resistance of 250 mΩ·cm 2 The following separators can reliably produce alkaline batteries with excellent discharge characteristics even under heavy load conditions.

[0033] Effects of the Invention

[0034] According to the present invention, manganese dioxide and silver oxide can be blended at an optimal ratio to achieve cost reduction, while the electrolyte can be an aqueous potassium hydroxide solution having an optimal concentration. Furthermore, by adjusting the molar ratio of potassium hydroxide to sodium hydroxide contained in the negative electrode to an optimal ratio, an alkaline battery with excellent discharge characteristics can be provided.

[0035] By adjusting the manganese dioxide blending ratio to a more preferred range and the molar ratio of potassium hydroxide to sodium hydroxide to a more preferred ratio, an alkaline battery with improved discharge characteristics can be provided. Furthermore, by adjusting the separator resistance to a low range, an alkaline battery with further improved discharge characteristics can be provided.

[0036] According to the manufacturing method of the present invention, a potassium hydroxide aqueous solution and a sodium hydroxide aqueous solution of a specific concentration are mixed at a specific mass ratio and prepared together with a negative electrode active material to form a negative electrode. A positive electrode containing a positive electrode active material obtained by blending silver oxide and manganese dioxide at a specific ratio is prepared, and an electrolyte solution of a specific concentration is used. Thus, an alkaline battery having excellent discharge characteristics can be provided while achieving low cost.

[0037] By adjusting the manganese dioxide blending ratio to a more preferred range and the molar ratio of potassium hydroxide to sodium hydroxide to a more preferred ratio, an alkaline battery with improved discharge characteristics can be produced. Furthermore, by adjusting the separator resistance to a low range, an alkaline battery with further improved discharge characteristics can be produced. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] [ Figure 1] is a perspective view of the alkaline battery involved in the first embodiment.

[0039] [ Figure 2 ] is a graph showing the relationship between the molar ratio of potassium hydroxide to sodium hydroxide and the discharge capacity in the negative electrode of the alkaline battery manufactured in the example.

[0040] [ Figure 3 ] is a graph showing the relationship between the resistance and discharge capacity of the separator of the alkaline battery manufactured in the example.

[0041] [ Figure 4 ] is a graph showing the relationship between the potassium hydroxide concentration in the electrolyte of the alkaline battery manufactured in the example and the discharge capacity.

[0042] [ Figure 5 ] is a graph showing the relationship between the manganese dioxide ratio and the discharge capacity of the alkaline batteries manufactured in Examples. DETAILED DESCRIPTION

[0043] Hereinafter, an embodiment in which the present invention is applied to a button-type alkaline battery will be described with reference to the drawings.

[0044] <First embodiment>

[0045] Figure 1 1 is a cross-sectional view showing a button-type alkaline battery according to the first embodiment of the present invention. Figure 1 As shown, the battery 1 of this embodiment is a battery containing a positive electrode mixture and a negative electrode mixture (described later) and an electrolyte solution in a flat metal container. The metal can includes a positive electrode can 2 and a negative electrode can 3 .

[0046] The positive electrode can 2 is made of, for example, stainless steel (SUS) or stainless steel plated with nickel. It is formed into, for example, a flat cylindrical shape (a shallow cup shape). It houses the positive electrode mixture 5 and serves as a positive electrode current collector.

[0047] The negative electrode can 3 is formed of a clad material having, for example, a three-layer structure comprising an outer surface layer made of nickel, a metal layer made of stainless steel (SUS), and a current collector layer made of copper. The negative electrode can 3 is formed, for example, into a flat cylindrical shape (a shallow cup shape). The negative electrode can 3 has a circular opening 3a formed in a folded manner. An annular gasket 4, for example, made of nylon, is attached to the opening 3a.

[0048] The negative electrode can 3 is fitted into the circular opening 2f of the positive electrode can 2 from the side where the gasket 4 is attached. The opening 2f of the positive electrode can 2 is then caulked toward the gasket 4 to seal it. This forms a disc-shaped (button-shaped or coin-shaped) container (housing) 8. A sealed space 8S is formed within container 8. The gasket 4 insulates and seals the positive electrode can 2 and the negative electrode can 3.

[0049] The sealed space 8S contains a positive electrode mixture 5, a separator 6, a negative electrode mixture 7, and an electrolyte solution (not shown). The positive electrode mixture 5 is placed on the positive electrode can 2 side, and the negative electrode mixture 7 is placed on the negative electrode can 3 side via the separator 6.

[0050] The positive electrode mixture 5 contains a positive electrode active material, a conductive agent, an electrolyte, a binder, additives, and the like.

[0051] The positive electrode active material is preferably a substance that can be used as a positive electrode active material when zinc or a zinc alloy is used as the negative electrode active material. For example, a mixture of silver oxide powder (Ag2O powder) and manganese dioxide powder (MnO2 powder) can be used as the positive electrode active material. Silver nickelate (AgNiO2) can also be added to the positive electrode active material.

[0052] As the conductive additive, for example, graphite can be used, and as the additive, for example, a hydrogen storage alloy (LaNi5) can be used.

[0053] When the positive electrode active material is a mixture of silver oxide powder and manganese dioxide powder, the positive electrode mixture preferably contains 50% by mass or less of manganese dioxide. The manganese dioxide content in the positive electrode mixture is preferably 25 to 50% by mass, and more preferably 25 to 44% by mass.

[0054] By setting the manganese dioxide content within the above range, the amount of silver oxide used can be reduced, leading to lower costs. Furthermore, the discharge characteristics can be improved, and in particular, a decrease in capacity at the end of discharge can be prevented during high current discharge.

[0055] As an example, manganese dioxide having physical properties of a MnO2 content of 91.0% or more, a content of particles having a particle size of 75 μm or less of 80.0% or more, and an alkaline potential of 220 mV or more can be used.

[0056] In this specification, when the upper and lower limits of component contents are expressed using "to", unless otherwise specified, the range includes both upper and lower limits. Therefore, 25-50% by mass means 25% to 50% by mass.

[0057] The negative electrode mixture 7 preferably contains, for example, a negative electrode active material, a thickener, an electrolyte (alkaline aqueous solution), and additives such as zinc oxide. Zinc oxide (ZnO) acts as a conductivity stabilizer. Additives may include a viscoelasticity modifier, resin powder, and the like.

[0058] As the negative electrode active material, zinc (Zn) powder or zinc alloy powder can be used, for example. As the thickener, polyacrylic acid, carboxymethyl cellulose, or a mixture of polyacrylic acid and carboxymethyl cellulose is preferred. The use of polyacrylic acid or carboxymethyl cellulose can improve the negative electrode mixture 7's affinity for the electrolyte and its ability to retain liquid.

[0059] The electrolyte contained in the negative electrode mixture 7 is preferably an alkaline aqueous solution, particularly a mixed aqueous solution of potassium hydroxide (KOH) and sodium hydroxide (NaOH). When the negative electrode mixture 7 is in the form of a gel, the mixture preferably contains potassium hydroxide and sodium hydroxide in a molar ratio of 89:11 to 96:4, and more preferably in a molar ratio of 89.70:10.30 to 95.76:4.24.

[0060] The negative electrode mixture 7, when combined with the electrolyte solution (30-50% KOH aqueous solution) described below, not only exhibits excellent conductivity but also maintains the electrolyte around the negative electrode active material (Zn) until the end of discharge. This improves the utilization efficiency of the active material, resulting in an alkaline battery with excellent discharge characteristics.

[0061] The alkaline aqueous solution used in the negative electrode mixture 7 is, for example, a 45% potassium hydroxide aqueous solution and a 27% sodium hydroxide aqueous solution. The weight ratio of the potassium hydroxide aqueous solution to the sodium hydroxide aqueous solution can be in the range of 88:12 to 95:5, for example, 91:9.

[0062] Based on the above relationship, potassium hydroxide and sodium hydroxide are contained in the negative electrode mixture 7 at a molar ratio of 89:11 to 96:4, more specifically, 89.70:10.30 to 95.76:4.24.

[0063] By setting the input ratio of the potassium hydroxide aqueous solution to 88-95% by mass, the target battery electrical characteristics (discharge capacity) can be obtained. In addition, by setting the input ratio of the potassium hydroxide aqueous solution to 95% by mass or less, the operability of the negative electrode mixture can be kept in a good state. Therefore, when manufacturing alkaline batteries, the handling of the negative electrode mixture can be facilitated. In order to obtain such battery electrical characteristics and the operability of the negative electrode mixture, the concentration and input ratio of the alkaline aqueous solution can be appropriately adjusted so as to achieve the molar ratio of potassium hydroxide to sodium hydroxide in the above-mentioned negative electrode mixture 7.

[0064] It should be noted that, unless otherwise specified, the concentration of the alkaline aqueous solution in this specification is expressed as a mass fraction (mass percentage concentration).

[0065] The viscoelasticity adjusting material is added as needed to adjust the viscoelasticity of the negative electrode mixture 7 to a level that allows for good handling and improves productivity. Resin powders that do not react with strongly alkaline electrolytes can be used as the viscoelasticity adjusting material. For example, polytetrafluoroethylene, polypropylene, polyamide, polyethylene powder, acrylic resin, etc. can be used as the viscoelasticity adjusting material.

[0066] It should be noted that the state of not reacting with the electrolyte means a state of not chemically reacting with the electrolyte and not absorbing the electrolyte.

[0067] The separator 6 is interposed between the positive electrode mixture 5 and the negative electrode mixture 7. As the separator 6, for example, an insulating film having a large ion permeability and high mechanical strength can be used.

[0068] As the separator 6, a material that can be used as a battery separator can be used, preferably having a strength of 250 mΩ·cm 2 The following resistance material. The diaphragm 6 is made of glass paper, graft film, etc. These materials can be used in combination, or a necessary number of films or sheets made of the same material can be overlapped and used. 2 The following resistive materials form the separator 6 and can be combined with the electrolyte solution described below to form an alkaline battery having excellent conductivity.

[0069] In this embodiment, the electrolyte filled into container 8 can be, for example, a potassium hydroxide aqueous solution having a concentration of 40-50%. The concentration of the potassium hydroxide aqueous solution is preferably 44-50%, more preferably 45-50%. When the concentration of the electrolyte is within this range, sufficient conductivity is achieved. While higher potassium hydroxide concentrations improve conductivity, a concentration exceeding 50% may deteriorate conductivity, potentially preventing sufficient discharge capacity.

[0070] (Method for manufacturing alkaline batteries)

[0071] To manufacture the alkaline battery 1, first prepare the positive electrode mixture 5 and the negative electrode mixture 7. Next, after injecting the electrolyte into the positive electrode can 2, the positive electrode mixture 5 is placed inside the positive electrode can 2. Next, after inserting the separator 6 and the gasket 4 into the positive electrode can 2, the electrolyte is injected. Then, after arranging the negative electrode mixture 7, the negative electrode can 3 is inserted. Finally, the opening 2f of the positive electrode can 2 is caulked and the shell 8 is sealed. In this way, a Figure 1 The alkaline battery 1 is shown.

[0072] To explain in more detail, to manufacture the alkaline battery 1, a granular positive electrode mixture 5 is filled into the positive electrode can 2. Next, a separator 6 is placed on the positive electrode mixture 5, and a gasket 4 is pressed into the positive electrode can 2. Then, a gel-like negative electrode mixture 7 is placed on the separator 6, and after the electrolyte is filled, the negative electrode can 3 is placed on top of the separator 6. Furthermore, the opening 2f of the positive electrode can 2 is caulked, and the shell 8 is sealed. In this way, a battery can be obtained. Figure 1 The alkaline battery 1 is shown.

[0073] When placing the gelled negative electrode mixture 7 on the separator 6, a mixture of potassium hydroxide and sodium hydroxide at a molar ratio of 89:11 to 96:4 is used as an electrolyte, thereby making it easy to handle. Therefore, the necessary amount of negative electrode mixture 7 can be placed without any problems.

[0074] In the alkaline battery 1 of this embodiment, manganese dioxide is blended at a preferred ratio of 50% by mass or less relative to the positive electrode mixture, reducing the amount of expensive silver oxide used. This reduces costs. Furthermore, a 40-50% potassium hydroxide aqueous solution is used as the electrolyte, and the molar ratio of potassium hydroxide to sodium hydroxide in the gelled negative electrode is preferably 89:11 to 96:4. Consequently, even under heavy load conditions, capacity reduction is prevented until the end of discharge, providing an alkaline battery 1 with excellent discharge characteristics.

[0075] While this embodiment has been described with respect to an alkaline battery 1 having a container 8 composed of a metal positive electrode can 2 and a negative electrode can 3, the present invention is not limited thereto. The container is not limited to metal; for example, the positive electrode container and the negative electrode container may be formed of a laminated film of metal foil and a resin layer.

[0076] That is, the structure of the container is not particularly limited, and any container that can be used for general batteries can be used.

[0077] Example

[0078] Trial production Figure 1 The button-shaped battery with the internal structure shown here was used in the tests described below. The dimensions of the button-shaped battery are 11.6 mm in diameter and 5.4 mm in height. The positive electrode can is made of stainless steel, and the negative electrode can is formed with a three-layer cladding material consisting of nickel, stainless steel, and copper.

[0079] As will be described later, inside the container consisting of the positive electrode can and the negative electrode can, Figure 1 As shown, the positive electrode mixture, separator, negative electrode mixture, and electrolyte were housed. After a gasket was attached, the positive electrode can was caulked and sealed, thereby producing a prototype alkaline battery.

[0080] (Production of positive electrode)

[0081] A granular positive electrode is produced by pressing 794.0 mg of a positive electrode mixture formed by mixing 65.0 mass% of silver oxide (Ag2O) as an active material, 31.0 mass% of manganese dioxide (MnO2) containing an acrylic polymer as a binder, 3.0 mass% of graphite as a conductive aid and 1.0 mass% of a hydrogen storage alloy (LaNi5).

[0082] When preparing the granular positive electrode, six other positive electrode particles were prepared with the manganese dioxide content changed to 0, 25, 39, 42, 49, and 59 mass %, and used to prepare trial alkaline batteries.

[0083] (Fabrication of negative electrode)

[0084] A gelled negative electrode mixture was prepared by mixing 58.4% by mass of zinc (Zn) powder as an active material, 0.5% by mass of polyacrylic acid and 2.8% by mass of carboxymethyl cellulose as thickeners, and 38.3% by mass of a negative electrode mixture electrolyte.

[0085] For the negative electrode mixture electrolyte, five different solutions were prepared using a 45% aqueous potassium hydroxide solution and a 27% aqueous sodium hydroxide solution in the following mixing ratios, resulting in a molar ratio of potassium hydroxide to sodium hydroxide in the negative electrode mixture ranging from 83:17 to 96:4. Prototype alkaline batteries were produced using these electrolyte solutions at each mixing ratio. The five mixing ratios were as follows: 83, 90, 92, 93, and 96% molar ratio of sodium hydroxide.

[0086] (Assembly process)

[0087] 30.2 μL of a 30-50% potassium hydroxide aqueous solution was injected into a positive electrode can with an outer diameter of 11.6 mm as the electrolyte. Next, the granular positive electrode mixture was placed on the inner bottom surface of the can, and two sheets of cellophane and grafted membrane laminated separators were stacked. A nylon gasket was then inserted into the can. Prototype alkaline batteries were then produced using the potassium hydroxide aqueous solution with the four compositions described below as the electrolyte.

[0088] Next, the negative electrode mixture is placed on the separator by scraping, the negative electrode can is inserted, and the positive electrode can is caulked to seal it.

[0089] Through the above process, a button-shaped prototype alkaline battery with a diameter of 11.6 mm and a height of 5.4 mm (so-called 44 size) was produced. 2 separator, and produced several trial alkaline batteries.

[0090] The electrical resistance of such a separator can generally be adjusted by adjusting various conditions such as the thickness of the cellophane and graft film, and the graft ratio of the graft film (the ratio obtained by dividing the weight of the grafted chains in the graft polymerization by the weight of the substrate).

[0091] The plurality of prototype alkaline batteries described above were subjected to the following tests.

[0092] A constant current (10 mA) discharge test was conducted on each prototype alkaline battery to determine the discharge capacity at a COV of 1.0 V. The constant current (10 mA) discharge test is equivalent to a heavy load test for button-type alkaline batteries.

[0093] The following Table 1 and Figure 2 The relationship between the molar ratio of potassium hydroxide and the discharge capacity measurement results of multiple trial alkaline batteries is shown. Multiple alkaline batteries were produced by changing the mixing molar ratio of potassium hydroxide to sodium hydroxide in the negative electrode mixture electrolyte.

[0094] In the negative electrode mixture, the total molar ratio of potassium hydroxide to sodium hydroxide is 100. Therefore, the value obtained by subtracting the molar ratio of potassium hydroxide shown in Table 1 from 100 corresponds to the molar ratio of sodium hydroxide. Furthermore, two prototype alkaline batteries of each type with different molar ratios were produced for testing. Therefore, the resulting discharge capacity values ​​represent the average of the two prototype alkaline batteries.

[0095] [Table 1]

[0096]

[0097]

[0098] From Table 1 and Figure 2 The relationship shown here indicates that the electrolyte solution contained in the negative electrode mixture of an alkaline battery is preferably an alkaline aqueous solution containing potassium hydroxide and sodium hydroxide in a molar ratio of 89:11 to 96:4. Even within this range, it is found that selecting a ratio of 90:10 to 96:4 can produce an alkaline battery with particularly excellent discharge capacity.

[0099] Table 2 below and Figure 3 The discharge capacity measurement results of multiple prototype alkaline batteries using various separators with different resistances are shown. Note that the molar ratio of potassium hydroxide to sodium hydroxide in the negative electrode mixture was fixed at 93.

[0100] In the negative electrode mixture, the total molar ratio of potassium hydroxide to sodium hydroxide is 100. Therefore, the molar ratio of sodium hydroxide is 7. Furthermore, two alkaline batteries each using separators of different resistances were produced for testing. Therefore, the discharge capacity values ​​obtained are the average of the two trial alkaline batteries.

[0101] [Table 2]

[0102] <![CDATA[Resistance of diaphragm / mΩ·cm 2 > Discharge capacity / mAh 176 109 250 97 525 85

[0103] As shown in Table 2 and Figure 3 As shown, the resistance of the separator exceeds 500 mΩ·cm 2 Therefore, the resistance of the separator is preferably 500 mΩ·cm 2 As for the resistance of the diaphragm, it is known that if it is 250mΩ·cm 2 Below, the discharge capacity can be sufficiently improved.

[0104] Table 3 below and Figure 4 The results of measuring the relationship between potassium hydroxide concentration and discharge capacity in each prototype alkaline battery are shown. Note that multiple prototype alkaline batteries were produced by varying the potassium hydroxide concentration in the electrolyte solution contained in the container along with the positive and negative electrodes.

[0105] [Table 3]

[0106] KOH concentration in electrolyte / mass% Discharge capacity / mAh 30 70 44 91 45 106 50 106

[0107] As shown in Table 3 and Figure 4 As shown in Table 3, the discharge capacity value of the prototype alkaline battery with a potassium hydroxide concentration of 30% in the electrolyte was significantly reduced. On the other hand, excellent discharge capacity values ​​were obtained in the prototype alkaline battery with a potassium hydroxide concentration of 44-50%. Figure 4 As a result, it is believed that the concentration of potassium hydroxide in the electrolyte is preferably in the range of 40 to 50%. In order to reliably obtain an excellent discharge capacity, it is believed that the range of 44 to 50% is more preferable.

[0108] Table 4 and Figure 5 The results of measuring the relationship between the manganese dioxide blending ratio and discharge capacity in each prototype alkaline battery are shown. Note that, regarding silver oxide and manganese dioxide constituting the positive electrode mixture, multiple prototype alkaline batteries were produced by varying the manganese dioxide blending ratio in the positive electrode mixture.

[0109] [Table 4]

[0110] <![CDATA[Positive electrode MnO2 ratio (mass%)]]> Discharge capacity / mAh 0 104 25 102 31 106 39 100 42 102 49 90 59 79

[0111] Table 4 and Figure 5 The alkaline battery with 0% manganese dioxide blended is an alkaline battery using a positive electrode active material composed solely of silver oxide. By replacing 50% or less of the silver oxide with manganese dioxide, an alkaline battery with minimal reduction in discharge capacity can be obtained.

[0112] It should be noted that when the blending amount of manganese dioxide is set to 44% by mass or less, more specifically within the range of 25 to 44% by mass, it can be seen that an alkaline battery with almost no reduction in discharge capacity can be provided, as compared with a prototype alkaline battery using a positive electrode active material composed solely of silver oxide.

[0113] Industrial applicability

[0114] The alkaline battery disclosed herein has excellent discharge characteristics and can be manufactured at low cost, and therefore has high industrial applicability.

[0115] Explanation of symbols

[0116] 1…battery, 2…positive electrode can, 3…negative electrode can, 4…gasket, 5…positive electrode mixture, 6…separator, 7…negative electrode mixture, 8…container (shell), 8S…sealed space.

Claims

1. An alkaline battery, comprising a positive electrode, a negative electrode, a separator and an electrolyte in a container, characterized in that: The electrolyte is a potassium hydroxide aqueous solution with a concentration of 40-50%. The negative electrode is composed of a gel-like negative electrode mixture containing a negative electrode active material and an alkaline aqueous solution. The alkaline aqueous solution contains potassium hydroxide and sodium hydroxide in a molar ratio of 89:11 to 96:

4. The positive electrode is composed of a positive electrode mixture having a positive electrode active material containing silver oxide and manganese dioxide. The blending ratio of manganese dioxide in the positive electrode mixture is 50 mass % or less.

2. The alkaline battery according to claim 1, characterized in that The electrolyte is a potassium hydroxide aqueous solution with a concentration of 44-50%.

3. The alkaline battery according to claim 1 or 2, characterized in that: The blending ratio of manganese dioxide in the positive electrode mixture is 25 to 44% by mass.

4. The alkaline battery according to any one of claims 1 to 3, characterized in that The resistance of the diaphragm is 250 mΩ·cm 2 the following.

5. The alkaline battery according to any one of claims 1 to 4, characterized in that The container has: Positive electrode tank, Negative tank, and A gasket seals the positive electrode can and the negative electrode can.

6. A method for manufacturing an alkaline battery, wherein a positive electrode, a negative electrode, a separator and an electrolyte are contained in a container, characterized in that: Prepare: A negative electrode composed of a gel-like negative electrode mixture, wherein the negative electrode mixture contains a negative electrode active material and a mixed aqueous solution of a 45% potassium hydroxide aqueous solution and a 27% sodium hydroxide aqueous solution in a mass ratio of 88:12 to 95:

5. A positive electrode, the positive electrode being composed of a positive electrode mixture having a positive electrode active material containing silver oxide and manganese dioxide, wherein the blending ratio of manganese dioxide in the positive electrode mixture is 50% by mass or less, and An electrolyte, wherein the electrolyte is composed of a potassium hydroxide aqueous solution with a concentration of 40 to 50%; The positive electrode, the negative electrode, the separator, and the electrolyte are accommodated in the container.

7. The method for manufacturing an alkaline battery according to claim 6, characterized in that: A potassium hydroxide aqueous solution with a concentration of 44-50% is used as the electrolyte.

8. The method for manufacturing an alkaline battery according to claim 6 or 7, characterized in that: As the positive electrode, a positive electrode in which the blending ratio of the manganese dioxide is 25 to 44% by mass is used.

9. The method for producing an alkaline battery according to any one of claims 6 to 8, characterized in that: The resistance used is 250mΩ·cm 2 The following separators were used as the separators.

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