JP2006179429A - Alkaline dry battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an alkaline dry battery restrained from drying-up of electrolyte liquid of a gelatinous anode at the last period of charging, with improved strength of a cathode mixture, excellent in a preservation property by restraining self-discharge caused by nickel oxyhydroxide. <P>SOLUTION: The cathode mixture of the alkaline dry battery comprises manganese dioxide and nickel oxyhydroxide as activators, graphite as conductive agent, polyethylene as binder, the electrolyte, and at least one kind of additives selected from ZnO, Ca(OH)<SB>2</SB>, and Y<SB>2</SB>O<SB>3</SB>. the density of the cathode mixture before injecting the electrolyte liquid is 3.2 to 3.5 g/cm<SP>3</SP>, and porosity of the cathode mixture is 10 to 18%. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an alkaline battery including nickel oxyhydroxide as an active material in a positive electrode mixture and employing an inside-out structure.

In alkaline dry batteries, a hollow cylindrical pellet positive electrode mixture containing manganese dioxide is placed in close contact with the battery can in a bottomed cylindrical battery can that also serves as a positive electrode terminal, and a gel is placed in the center via a separator. It has an inside-out type structure in which a zinc negative electrode is arranged.
With the spread of digital devices in recent years, the load power of devices has increased. For this reason, the battery used for the power supply of a digital device is requested | required to have the outstanding heavy load discharge characteristic. As a method for improving the heavy load discharge characteristics, it has been proposed to mix nickel oxyhydroxide with the positive electrode mixture of the battery (for example, Patent Document 1), and this battery is put into practical use and widely spread. ing.

  Here, for the nickel oxyhydroxide used in the above alkaline dry battery, a spherical or egg-shaped nickel hydroxide used for alkaline storage battery as in Patent Document 2 is replaced with an oxidizing agent such as an aqueous sodium hypochlorite solution. It is common to use one oxidized with At this time, β-type spherical oxyhydroxide obtained by oxidizing β-type spherical nickel hydroxide having a large bulk density (tap density) and oxidizing it in order to improve the filling into the battery. Nickel is used.

By the way, conventionally, various design conditions for alkaline dry batteries using the above nickel oxyhydroxide have been studied.
For example, in Patent Document 3, regarding the blending of the active material in the positive electrode mixture, the content of manganese dioxide is set to 20 to 90% by weight and the content of nickel oxyhydroxide is set to 10 to 10% from the balance of battery characteristics, manufacturing cost, and the like. It has been proposed to be 80% by weight.
Patent Document 4 proposes that the value of the electrolytic solution amount / the positive electrode theoretical capacity is 1.0 to 1.6 cm ³ / Ah.
Usually, a mixture of these active materials and a conductive agent, a binder or the like is pressed into a hollow cylindrical shape to obtain a positive electrode mixture having a density of about 3 g / cm ³ (porosity of about 20%). A gelled negative electrode is filled through a separator and an alkaline electrolyte is injected to produce a battery. At this time, the amount of zinc (active material) in the negative electrode is as much as possible because of measures for leakage during overdischarge (a measure to prevent the positive electrode from reversing and generating hydrogen during overdischarge and the battery internal pressure to rise rapidly). It is common to design with fewer.
JP-A-57-72266 Japanese Patent Laid-Open No. 4-80513 JP 2001-15106 A International Publication No. 02 / 41422A1 Pamphlet

However, in the design of the conventional nickel oxyhydroxide-containing alkaline battery as described above, since the density of the positive electrode mixture is low (the porosity is high), the electrolyte is biased toward the positive electrode mixture side at the end of discharge, and the gelled negative electrode There was a problem that the electrolyte inside was easily depleted.
Here, the discharge reaction of the nickel oxyhydroxide-containing alkaline battery is represented by the following formulas (1) to (4). Formulas (1) and (2) show the discharge reaction in the positive electrode mixture, and formulas (3) and (4) show the discharge reaction in the gelled negative electrode.
<Positive electrode>
NiOOH + H ₂ O + e ⁻ → Ni (OH) ₂ + OH ⁻ (1)
_{MnO 2 + H 2 O + e} - → MnOOH + OH - (2)
<Negative electrode>
Zn + 2OH ⁻ → Zn (OH) ₂ + 2e ⁻ (3)
Zn + 2OH ⁻ → ZnO + H ₂ O + 2e ⁻ (4)

  While the discharge reaction of the positive electrode is a water consumption reaction for both nickel oxyhydroxide and manganese dioxide, the discharge reaction of the negative electrode includes the reaction of formula (3) that does not include the generation of water. Along with this, water decreases. Then, the concentration gradient of the alkaline electrolyte generated at this time becomes a driving force, and the electrolyte (water) in the gelled negative electrode diffuses toward the positive electrode mixture side. Therefore, generally, a phenomenon occurs in which the electrolyte in the gelled negative electrode is depleted at the end of discharge, and the capacity may not be taken out sufficiently.

In particular, when an alkaline battery is stored for a long period of time, zinc powder is oxidized and deteriorated by the reaction of formula (5) shown below (water consumption reaction) in a gelled negative electrode. Also by this reaction, the electrolyte solution (water) in the negative electrode decreases, so that the electrolyte solution tends to be depleted in the negative electrode at the end of discharge.
Zn + H ₂ O → ZnO + H ₂ (5)
For this reason, it is considered important to inject as much electrolyte as possible. On the other hand, if the amount of electrolyte is excessive, the air space in the battery decreases, so the battery internal pressure rises or leaks during overdischarge. It becomes difficult to suppress the occurrence of this. In other words, there is a limit to measures by increasing the amount of electrolyte.
Therefore, in order to solve the above-described conventional problems, the present invention suppresses the depletion of the alkaline electrolyte in the gel negative electrode at the end of discharge, and increases the active material utilization rate of the gel negative electrode, thereby increasing the high-capacity alkali. An object is to provide a dry battery. Moreover, it aims at providing the alkaline dry battery excellent in the storage characteristic by raising the intensity | strength of positive mix and suppressing the self-discharge by nickel oxyhydroxide.

Accordingly, the present invention provides a battery can having a hollow cylindrical positive electrode mixture, a gelled negative electrode containing zinc as an active material, a negative electrode current collector inserted into the negative electrode, the positive electrode mixture and the gelled negative electrode, Separator, and an alkaline dry battery containing an electrolytic solution comprising an alkaline aqueous solution, wherein the positive electrode mixture is manganese dioxide and nickel oxyhydroxide as an active material, graphite as a conductive agent, polyethylene powder as a binder, The electrolyte solution and at least one additive selected from the group consisting of ZnO, Ca (OH) ₂ , and Y ₂ O ₃ are included, and the density of the positive electrode mixture before injection of the electrolyte solution is 3. It is 2 to 3.5 g / cm ³ , and the porosity of the positive electrode mixture is 10 to 18%.

  As a result, the gelled negative electrode can sufficiently hold the alkaline electrolyte even at the end of discharge, and the active material utilization of the gelled negative electrode is improved, so that the capacity of the alkaline dry battery can be increased. Furthermore, the storage characteristics of an alkaline battery dry battery are improved by adding the above-mentioned binder or additive to the positive electrode mixture. The positive electrode mixture before injecting the electrolytic solution is a state containing a small amount of the electrolyte added at the time of preparing the positive electrode mixture, and a predetermined amount of electrolysis is contained in the battery can containing the positive electrode mixture. This refers to the state before the liquid is injected.

Further, the alkaline dry battery preferably satisfies the following (1) to (3).
(1) The value of the theoretical capacity of the gelled negative electrode / the theoretical capacity of the positive electrode mixture is 1.00 to 1.15.
(2) Porosity in the battery can (the volume occupied by the positive electrode mixture, gelled negative electrode, separator, alkaline electrolyte, and negative electrode current collector from the volume in the battery can relative to the volume in the battery can) The ratio of the volume of the removed void portion) is 5 to 15%.
(3) The value of the theoretical amount of the electrolytic solution amount / the gelled negative electrode is 1.0 to 1.4 cm ³ / Ah.
Here, the volume in the battery can in (2) is the volume of the portion surrounded by the battery can and the resin sealing plate disposed in the opening of the battery can. The amount of electrolyte in (3) is the total amount of electrolyte present in the battery, that is, the amount of electrolyte added to the positive electrode mixture and the gelled negative electrode during the preparation of the positive electrode mixture and the gelled negative electrode and the battery assembly. This is the total amount of electrolyte solution that is sometimes poured into the battery can.

The positive electrode mixture includes 10 to 80 parts by weight of the nickel oxyhydroxide and 85 to 15 parts by weight of the manganese dioxide with respect to 100 parts by weight of a mixture of manganese dioxide, nickel oxyhydroxide, and graphite. preferable.
The positive electrode mixture preferably contains 3 to 10 parts by weight of the graphite with respect to 100 parts by weight of a mixture of manganese dioxide, nickel oxyhydroxide, and graphite.
The positive electrode mixture preferably contains 0.1 to 1 part by weight of the polyethylene powder with respect to 100 parts by weight of a mixture of manganese dioxide, nickel oxyhydroxide, and graphite.
The positive electrode mixture preferably contains 0.1 to 3 parts by weight of the additive with respect to 100 parts by weight of a mixture of manganese dioxide, nickel oxyhydroxide, and graphite.
The volume-based average particle diameter of the manganese dioxide is preferably 30 to 50 μm, and the volume-based average particle diameter of the nickel oxyhydroxide is preferably 10 to 30 μm.

  According to the present invention, the gelled negative electrode can sufficiently hold the alkaline electrolyte even at the end of discharge, and the active material utilization of the gelled negative electrode is improved, so that the capacity of the alkaline dry battery can be increased. Moreover, since the strength of the positive electrode mixture is improved and self-discharge due to nickel oxyhydroxide is suppressed, an alkaline dry battery having excellent storage characteristics can be obtained.

The present invention provides a battery can comprising a hollow cylindrical positive electrode mixture, a gelled negative electrode containing zinc as a negative electrode active material, a negative electrode current collector inserted into the negative electrode, the positive electrode mixture and the gelled negative electrode. The present invention relates to a separator to be isolated and an alkaline dry battery containing an electrolytic solution made of an alkaline aqueous solution.
The positive electrode mixture is manganese dioxide and nickel oxyhydroxide as a positive electrode active material, graphite as a conductive agent, polyethylene powder as a binder, the electrolytic solution, ZnO, Ca (OH) ₂ , and Y ₂ O _3. The positive electrode mixture has a density of 3.2 to 3.5 g / cm ³ before pouring of the electrolyte solution, and the porosity of the positive electrode mixture is at least one selected from the group consisting of It is characterized in that the degree is 10 to 18%.
The positive electrode mixture is, for example, a hollow granulated product obtained by stirring and mixing a mixture of nickel oxyhydroxide and manganese dioxide as a positive electrode active material, graphite and the like as a conductive agent, and a small amount of electrolyte. It can be obtained by pressure molding into a cylindrical shape. Thereafter, the positive electrode mixture is accommodated in the battery can, and a predetermined amount of electrolyte is injected into the battery can after the separator is inserted. Therefore, the positive electrode mixture before the injection of the electrolytic solution in the above means a state containing a small amount of the electrolytic solution added at the time of production.

In a conventional nickel oxyhydroxide-containing alkaline dry battery, the density of the positive electrode mixture before injection is usually about 3.0 g / cm ³ (porosity is about 20%) from the viewpoint of productivity and the like. In the present invention, the density of the positive electrode mixture before injection is increased to 3.2 to 3.5 g / cm ³ (porosity is 10 to 18%) to constitute a battery. In this case, since the volume of the voids in the positive electrode mixture is reduced, the diffusion of the electrolyte solution from the gelled negative electrode to the positive electrode mixture side is effectively suppressed, and the electrolyte solution is contained in the gelled negative electrode even at the end of discharge. Can be kept sufficiently, and a sufficient electric capacity can be taken out from the negative electrode. Further, increasing the density of the positive electrode mixture as described above is also advantageous from the viewpoint that a large amount of active material can be filled in the battery can to increase the capacity.
Considering the productivity in the actual process, the density of the positive electrode mixture is more preferably 3.2 to 3.35 g / cm ³ .

By including polyethylene powder in the positive electrode mixture, the contact between manganese dioxide and nickel oxyhydroxide in the positive electrode mixture is improved, and at the same time, the strength of the positive electrode mixture is sufficiently improved.
In addition, the positive electrode mixture contains at least one additive selected from the group consisting of ZnO (zinc oxide), Ca (OH) ₂ (calcium hydroxide), and Y ₂ O ₃ (yttrium oxide). As a result, the overvoltage of the oxygen generation reaction in the nickel oxyhydroxide is increased, and the self-discharge is alleviated.
Therefore, when the positive electrode mixture contains the binder and additive as described above, a decrease in the positive electrode capacity during storage is suppressed.

Further, the alkaline dry battery preferably satisfies the following (1) to (3).
(1) The value of the theoretical capacity of the gelled negative electrode / the theoretical capacity of the positive electrode mixture (hereinafter referred to as negative electrode theoretical capacity / positive electrode theoretical capacity) is 1.00 to 1.15.
(2) Porosity in the battery can (the volume occupied by the positive electrode mixture, gelled negative electrode, separator, alkaline electrolyte, and negative electrode current collector from the volume in the battery can relative to the volume in the battery can) The ratio of the volume of the removed void portion) is 5 to 15%.
(3) The value of the electrolytic solution amount / the theoretical capacity of the gelled negative electrode (hereinafter referred to as the electrolytic solution amount / negative electrode theoretical capacity) is 1.0 to 1.4 cm ³ / Ah.
Here, the volume in the battery can in (2) is the volume of the portion surrounded by the battery can and the resin sealing plate disposed in the opening of the battery can. The amount of electrolyte in (3) is the total amount of electrolyte present in the battery, that is, the amount of electrolyte added to the positive electrode mixture and the gelled negative electrode during the preparation of the positive electrode mixture and the gelled negative electrode and the battery assembly. This is the total amount of electrolyte solution that is sometimes poured into the battery can.

If the value of negative electrode theoretical capacity / positive electrode theoretical capacity is less than 1.00, zinc of the negative electrode active material is insufficient and sufficient capacity cannot be obtained. On the other hand, if the value of the negative electrode theoretical capacity / the positive electrode theoretical capacity exceeds 1.15, the discharge capacity is regulated by the positive electrode. It may rise and cause leakage.
If the porosity is less than 5%, gas may be generated in the battery due to overdischarge or the like, and the internal pressure of the battery can may increase rapidly. On the other hand, when the porosity is higher than 15%, the amount of the active material of the positive electrode and the negative electrode is limited, so that it is substantially difficult to increase the capacity of the battery.
When the value of the electrolytic solution amount / the negative electrode theoretical capacity is less than 1.0 cm ³ / Ah, the electrolytic solution in the gelled negative electrode tends to be exhausted at the end of discharge. On the other hand, when the value of the electrolytic solution amount / the negative electrode theoretical capacity exceeds 1.4 cm ³ / Ah, the electrolytic solution amount becomes excessive and liquid leakage tends to occur.

The positive electrode mixture includes 10 to 80 parts by weight of the nickel oxyhydroxide and 85 to 15 parts by weight of the manganese dioxide with respect to 100 parts by weight of a mixture of manganese dioxide, nickel oxyhydroxide, and graphite. preferable.
When comparing manganese dioxide and nickel oxyhydroxide, manganese dioxide is superior in terms of capacity per unit weight (mAh / g), fillability in the battery can, and material price. Regarding heavy load discharge characteristics, nickel oxyhydroxide is superior. Considering the balance of characteristics and price as a whole battery, the positive electrode mixture preferably contains nickel oxyhydroxide and manganese dioxide in the above range. More preferably, the mixing weight ratio of manganese dioxide and nickel oxyhydroxide is 30-60: 70-40.

The positive electrode mixture preferably contains 3 to 10 parts by weight of the graphite with respect to 100 parts by weight of a mixture of manganese dioxide, nickel oxyhydroxide, and graphite.
When the content of graphite is 3 parts by weight or more, the volume energy density of the active material in the positive electrode mixture is sufficiently increased, and the heavy load discharge characteristics are improved. When the content of graphite exceeds 10 parts by weight, the amount of the positive electrode active material is relatively reduced, so that it is difficult to increase the capacity of the battery. On the other hand, if the graphite content is less than 3 parts by weight, the above-described effects of graphite cannot be obtained sufficiently. More preferably, it contains 5 to 8 parts by weight of graphite with respect to 100 parts by weight of the mixture.

  The positive electrode mixture preferably contains 0.1 to 1 part by weight of polyethylene powder with respect to 100 parts by weight of a mixture of manganese dioxide, nickel oxyhydroxide, and graphite. When the content of the polyethylene powder is less than 0.1 parts by weight, the discharge performance after storage of the battery is greatly deteriorated. On the other hand, when the content of the polyethylene powder exceeds 1 part by weight, the internal resistance of the battery is increased and the initial discharge performance is lowered. More preferably, the positive electrode mixture includes 0.2 to 0.5 parts by weight of polyethylene powder with respect to 100 parts by weight of the mixture.

The positive electrode mixture contains at least one additive selected from the group consisting of ZnO, Ca (OH) ₂ , and Y ₂ O _{3 with} respect to 100 parts by weight of a mixture of manganese dioxide, nickel oxyhydroxide, and graphite. It is preferable to contain 0.1-3 weight part.
If the content of the additive is less than 0.1 parts by weight, the effect of suppressing the self-discharge reaction of nickel oxyhydroxide is slight, and the discharge performance after storage of the battery is greatly reduced. On the other hand, when the content of the additive exceeds 3 parts by weight, the amount of the positive electrode active material is relatively small, and it is difficult to increase the capacity of the battery. More preferably, the positive electrode mixture includes 0.2 to 2 parts by weight of the additive with respect to 100 parts by weight of the mixture.

The volume-based average particle diameter of the manganese dioxide is preferably 30 to 50 μm, and the volume-based average particle diameter of the nickel oxyhydroxide is preferably 10 to 30 μm.
The particle diameter of manganese dioxide can be controlled, for example, by adjusting the pulverization conditions of manganese dioxide peeled from the electrode in the electrodeposition process. Generally, when the particle size is too small, the discharge capacity is reduced, and when the particle size is too large, the high-load discharge characteristics are deteriorated. Moreover, the one with a larger particle diameter is easier to make a positive electrode mixture pellet. Considering these points, the volume-based average particle size of manganese dioxide is preferably 30 to 50 μm.

  The particle diameter of nickel oxyhydroxide can be adjusted, for example, by adjusting the pH in the synthesis tank, the residence time of the particles, the reaction temperature, etc., when nickel hydroxide as a base material is synthesized by a reaction crystallization method. It is possible to control. Even when a product having a large particle size is intentionally produced, the average particle size (volume basis) often remains at about 30 μm. In the present invention, it is preferable to use nickel oxyhydroxide obtained from nickel hydroxide having a large particle size from the viewpoint of increasing the density of the positive electrode mixture (improving moldability). Considering these points, the volume-based average particle diameter of nickel oxyhydroxide is preferably 10 to 30 μm.

Examples of the present invention will be described in detail below.
Example 1
(1) Preparation of positive electrode mixture In a reaction vessel equipped with a stirring blade, pure water and a small amount of hydrazine (reducing agent) are added, and bubbling with nitrogen gas is performed, and a nickel (II) sulfate aqueous solution with a predetermined concentration and sulfuric acid are added. Manganese (II) aqueous solution, sodium hydroxide aqueous solution, and aqueous ammonia were supplied by a pump. And nickel hydroxide was deposited and grown by continuing sufficient stirring, adjusting pH in a tank. At this time, the content of manganese in nickel hydroxide was adjusted to 5 mol% with respect to the total amount of metal ions.
Subsequently, the obtained particles were heated in an aqueous sodium hydroxide solution different from the above to remove sulfate radicals, then washed with water and vacuum dried to obtain powdered nickel hydroxide (composition: Ni _{0). .95} Mn _0.05 (OH) ₂ ) was obtained. This nickel hydroxide was confirmed to have a β-type crystal structure by using a powder X-ray diffraction measurement apparatus (RINT 2500, manufactured by Rigaku Corporation).

Next, 200 g of the above nickel hydroxide was put into 1 L of a 0.1 mol / L sodium hydroxide aqueous solution, and a sufficient amount of an aqueous sodium hypochlorite solution (effective chlorine concentration: 10% by weight) was further added as an oxidant and stirred. Then, nickel hydroxide was oxidized to obtain powdered nickel oxyhydroxide. The obtained nickel oxyhydroxide powder was sufficiently washed with water and then vacuum-dried at 60 ° C. for 24 hours. The nickel oxyhydroxide had a β-type crystal structure, and had a volume-based average particle size of 20 μm, a tap density of 2.35 g / cm ³ , and a BET specific surface area of 12 m ² / g. The tap density indicates the bulk density of the sample powder when the container containing the sample powder is tapped 300 times. For X-ray diffraction measurement, a powder X-ray diffraction device (RINT 2500, manufactured by Rigaku Corporation) was used, and for measuring the average particle size, a particle size distribution measuring device (manufactured by Nikkiso Co., Ltd., Microtrac FRA) was used. Used, tap density KYT-3000 manufactured by Seishin Co., Ltd. was used for measuring the tap density, and ASAP2010 manufactured by Shimadzu Corporation was used for measuring the BET specific surface area.
Then, the nickel oxyhydroxide, manganese dioxide (volume basis average particle size: 40 μm) and graphite obtained above were mixed at a weight ratio of 50: 45: 5, and 100 parts by weight of this mixture was mixed with polyethylene powder 0 After mixing 3 parts by weight, 1 part by weight of ZnO powder, and 1 part by weight of a 40% by weight aqueous potassium hydroxide solution as an electrolyte, the mixture was uniformly stirred and mixed with a mixer to adjust the particle size to a constant particle size. And the predetermined amount of the obtained granulated material was press-molded into a hollow cylindrical shape to obtain a positive electrode mixture.

(2) Assembly of alkaline battery An alkaline battery can was prepared by the following procedure using the positive electrode mixture obtained above. Here, FIG. 1 is a front view of a part of the alkaline dry battery of the present invention. A plurality of positive electrode mixtures 73 obtained as described above are inserted into a battery can 71 also serving as a positive electrode terminal, which is made of a nickel-plated steel plate and has a graphite coating film 72 formed on the inner surface thereof. The inside of the battery can 71 was brought into close contact with the inside by repressurization.

  And after inserting the separator 74 and the insulating cap 75 in the hollow inner surface of the positive electrode mixture 73 and the bottom inner surface of the battery can 71, the electrolyte solution was injected for the purpose of wetting the separator 74 and the positive electrode mixture 73. . A 40 wt% aqueous potassium hydroxide solution was used as the electrolytic solution. After the injection, the gelled negative electrode 76 was filled inside the separator 74. As the gelled negative electrode 76, a material comprising sodium polyacrylate as a gelling agent, 40% by weight potassium hydroxide aqueous solution as an electrolytic solution, and zinc powder as a negative electrode active material was used.

  Subsequently, the negative electrode current collector 70 was inserted into the center of the gelled negative electrode 76. The negative electrode current collector 70 is integrally assembled with a resin sealing plate 77, a bottom plate 78 also serving as a negative electrode terminal, and an insulating washer 79. And the opening part of the battery can 71 was sealed by caulking the opening edge part of the battery can 1 to the peripheral part of the bottom plate 78 via the peripheral edge part of the sealing board 77. FIG. Next, the outer surface of the battery can 71 was covered with an exterior label 711. Thus, an AA alkaline battery was completed.

And the positive pressure mixture A1-A7 of the density (porosity) as shown in Table 1 was produced by changing the pressure at the time of the pressure molding of a positive electrode mixture variously in the above.
In addition, the density of the positive electrode mixture shown in Table 1 is a value when 1 part by weight of the electrolytic solution added at the time of granulation is included. The density of the positive electrode mixture was measured in advance by measuring the weight of the positive electrode mixture pellets before being stored in the battery can, and the weight (g) of the positive electrode mixture after re-pressurization in the battery can (cm ³ ).
Moreover, the true density of each material of the positive electrode mixture was obtained using a density measuring device (Accumpic 1330 manufactured by Micromeritic), and the true material volume corresponding to the weight of the positive electrode mixture was calculated. Then, using this true material volume, the value calculated from the formula (volume of positive electrode mixture−true material volume) / volume of positive electrode mixture × 100 was defined as the porosity of the positive electrode mixture.
And alkaline dry batteries A1-A7 were each produced by said method using these positive electrode mixtures.

[Battery evaluation]
The batteries A1 to A7 obtained above were each continuously discharged at a constant current of 250 mA in a 20 ° C. environment, and the discharge capacity until the battery voltage reached 0.9 V was measured. The obtained results are shown in Table 2. The discharge capacity in Table 2 was expressed as an index with the discharge capacity of the battery A1 as 100.

From Table 2, the discharge capacity of the batteries A3 to A6 in which the density of the positive electrode mixture before pouring the electrolyte into the battery can is 3.2 to 3.5 g / cm ³ (10 to 18% as the porosity). Was found to improve. In the batteries A1 and A2, the electrolyte solution (water) in the gelled negative electrode diffuses toward the positive electrode mixture side at the end of discharge, and the electrolyte solution in the negative electrode is depleted, whereas in the batteries A3 to A6, the positive electrode mixture Because the porosity is small, the diffusion of the electrolyte from the gelled negative electrode to the positive electrode mixture is suppressed, and a sufficient amount of alkaline electrolyte is retained in the gelled negative electrode even at the end of discharge, so that the negative electrode capacity can be sufficiently drawn out. It is guessed. In Battery A7, since the porosity of the positive electrode mixture was too small, the electrolytic solution in the positive electrode mixture was insufficient, and the battery capacity was reduced.

Example 2
In this example, the capacity balance between the positive electrode and the negative electrode (negative electrode theoretical capacity / value of positive electrode theoretical capacity) was examined. The positive electrode mixture used was the positive electrode mixture A4 of Example 1, and the gelled negative electrode was the same as in Example 1. Then, the filling amount of the positive electrode mixture A is constant, and the negative electrode theoretical capacity / positive electrode theoretical capacity value and the porosity are set to the values shown in Table 3, and the gel negative electrode filling amount and the battery can are poured. Alkaline dry batteries B1 to B6 were assembled in the same manner as in Example 1 except that the amount of electrolyte to be liquefied was adjusted. In addition, the porosity was calculated | required by calculating the volume of each component and space using three-dimensional CAD.
For these batteries, the discharge capacity was measured in the same manner as in Example 1.
Further, 20 cells of the battery B1 were prepared, connected in series via a 10Ω resistor, and left in a 20 ° C. atmosphere for 1 week to discharge the battery. And the occurrence rate (leakage rate) of the leak in the battery at the time of overdischarge was calculated | required. For the batteries B2 to B6, the leakage rate was determined in the same manner as for B1.

The porosity is the ratio of the volume of the void portion excluding the volume occupied by the positive electrode mixture, the gelled negative electrode, the separator, the alkaline electrolyte, and the negative electrode current collector from the volume in the battery can relative to the volume in the battery can. It is. In this embodiment, as shown in FIG. 1, since a part of the negative electrode current collector 70 is inserted into a hole provided in the center of the sealing plate 77, the volume in the battery can is the same as that of the battery can 71. The volume of the portion surrounded by the sealing plate 77 including the hole into which the negative electrode current collector 70 was inserted was used. The volume occupied by the negative electrode current collector was the volume occupied by the portion excluding the portion inserted into the hole of the sealing plate 77 from the entire negative electrode current collector 70.
These measurement results are shown in Table 3. The discharge capacity in Table 3 was expressed as an index with the discharge capacity of the battery B4 as 100.

From Table 3, when the value of the negative electrode theoretical capacity / the positive electrode theoretical capacity is less than 1.00, the amount of the negative electrode active material is too small to obtain sufficient discharge performance, and the value of the negative electrode theoretical capacity / the positive electrode theoretical capacity is 1. It was found that liquid leakage occurred during overdischarge when it increased to 20. Here, the leakage generated in the battery B6 is due to the large amount of the negative electrode active material, so that the battery capacity is restricted to the positive electrode, the positive electrode is reversed during overdischarge, hydrogen is generated, and the internal pressure of the battery is rapidly increased. It is guessed.
From the above results, it was found that the capacity balance (negative electrode theoretical capacity / positive electrode theoretical capacity) of the positive electrode and the negative electrode is preferably 1.00 to 1.15 in the present invention.

Example 3
In this example, the porosity in the battery can was examined. The positive electrode mixture was the positive electrode mixture A4 of Example 1, and the gelled negative electrode was the same as that of Example 1. With the positive electrode mixture C filling amount being constant, the ratio of the porosity, the amount of electrolytic solution / the negative electrode theoretical capacity, and the negative electrode theoretical capacity / the positive electrode theoretical capacity are the values shown in Table 4, Alkaline dry batteries C1 to C7 were assembled by the same method as in Example 1 except that the filling amount and the amount of the electrolyte solution poured into the battery can were adjusted.
For these batteries, the discharge capacity and the liquid leakage rate were measured in the same manner as in Example 2.
These measurement results are shown in Table 4. The discharge capacity in Table 4 was expressed as an index with the discharge capacity of the battery C4 as 100.

When the porosity is less than 5.0% (the amount of electrolytic solution / theoretical capacity of negative electrode exceeds 1.4 cm ³ / Ah), the battery internal pressure at the time of overdischarge increases significantly and leakage occurs. When the porosity exceeds 15% (the value of the amount of electrolytic solution / theoretical capacity of negative electrode is less than 1.0 cm ³ / Ah), the amount of the electrolytic solution is too small to obtain sufficient discharge performance.
From the above results, it was found that the porosity is preferably 5 to 15%, and the value of the electrolytic solution amount / the negative electrode theoretical capacity is preferably 1.0 to 1.4 cm ³ / Ah.

Example 4
In this example, the mixing ratio of manganese dioxide and nickel oxyhydroxide in the positive electrode mixture was examined. Positive electrode mixtures D1 to D10 were obtained in the same manner as in Example 1 except that manganese dioxide, nickel oxyhydroxide, and graphite were mixed in the ratio shown in Table 5. At this time, the density of the positive electrode mixture was about 3.3 g / cm ³ and the porosity was 15 to 16%.
With respect to these positive electrode mixtures D1 to D10, the negative electrode theoretical capacity / positive electrode theoretical capacity value was 1.10, the porosity was 10%, and the electrolyte amount / negative electrode theoretical capacity value was about 1.2 cm ³ / Ah. The alkaline dry batteries D1 to D10 were assembled in the same manner as in Example 1 except that the amount of the gelled negative electrode and the amount of the electrolyte injected into the battery can were adjusted.

  Each battery obtained above was continuously discharged at a constant current of 50 mA (low load) or 1000 mA (high load) at 20 ° C., and the discharge capacity until the battery voltage reached 0.9 V was measured. These measurement results are shown in Table 5. The discharge capacity in Table 5 was expressed as an index with the discharge capacity of the battery D5 as 100 in both cases of 50 mA discharge and 1000 mA discharge.

In batteries D8 to D10, the discharge capacity during 50 mA (low load) discharge was reduced, and in batteries D1 and D2, the discharge capacity during 1000 mA (high load) discharge was reduced.
From the above results, it was found that the content of nickel oxyhydroxide is preferably 10 to 80 parts by weight and the content of manganese dioxide is preferably 85 to 15 parts by weight.

Example 5
In this example, the amount of polyethylene powder added as a binder to the positive electrode mixture was examined. According to the same method as in Example 1, except that the addition amount of polyethylene powder was changed as shown in Table 6 with respect to 100 parts by weight of a mixture of manganese dioxide, nickel oxyhydroxide, and graphite, positive electrode mixtures E1 to E6 were prepared. Obtained. Furthermore, a positive electrode mixture E7 was obtained in the same manner as in Example 1 except that polyethylene powder was not added.
With respect to these positive electrode mixtures E1 to E7, the negative electrode theoretical capacity / positive electrode theoretical capacity value was 1.10, the porosity was 10%, and the electrolyte amount / negative electrode theoretical capacity value was about 1.2 cm ³ / Ah. The alkaline dry batteries E1 to E7 were assembled in the same manner as in Example 1 except that the amount of the gelled negative electrode and the amount of the electrolyte injected into the battery can were adjusted.

  About each battery immediately after manufacture (first time) obtained above, 50 mA discharge capacity and 1000 mA discharge capacity were measured in the same manner as in Example 4. In addition, the battery after being stored in a 60 ° C. environment for one week was continuously discharged at a constant current of 1000 mA, the discharge capacity up to a final voltage of 0.9 V was measured, and after storage at 60 ° C. for the initial 1000 mA discharge capacity. The ratio of the 1000 mA discharge capacity was determined as the capacity retention rate. These measurement results are shown in Table 6. The discharge capacity in Table 6 was expressed as an index with the discharge capacity of the battery E3 as 100 in both cases of 50 mA discharge and 1000 mA discharge.

電池Ｅ１およびＥ７では容量維持率が低下し、電池Ｅ６では初度の放電性能が低下した。以上の結果から、ポリエチレン粉末の添加量は、二酸化マンガン、オキシ水酸化ニッケル、および黒鉛の混合物１００重量部に対して０．１〜１重量部であるのが好ましいことがわかった。

In the batteries E1 and E7, the capacity retention rate was lowered, and in the battery E6, the initial discharge performance was lowered. From the above results, it was found that the addition amount of the polyethylene powder is preferably 0.1 to 1 part by weight with respect to 100 parts by weight of the mixture of manganese dioxide, nickel oxyhydroxide, and graphite.

Example 6
In this example, the types and amounts of additives added to the positive electrode mixture were examined.
Instead of adding 1 part by weight of ZnO powder as an additive to 100 parts by weight of a mixture of manganese dioxide, nickel oxyhydroxide, and graphite, the addition amount and the kind of additive were variously changed as shown in Table 7. Except for the above, positive electrode mixtures F1 to F18 were obtained in the same manner as in Example 1. A positive electrode mixture F19 was obtained in the same manner as in Example 1 except that no additive was added.

With respect to these positive electrode mixtures F1 to F19, the negative electrode theoretical capacity / positive electrode theoretical capacity value was 1.10, the porosity was 10%, and the electrolyte amount / negative electrode theoretical capacity value was about 1.2 cm ³ / Ah. The alkaline dry batteries F1 to F19 were assembled in the same manner as in Example 1 except that the amount of the gelled negative electrode and the amount of the electrolyte injected into the battery can were adjusted.
Each battery obtained above was evaluated in the same manner as in Example 5. These measurement results are shown in Table 7. The discharge capacity in Table 7 was expressed as an index with the discharge capacity of the battery F3 set to 100 in both cases of 50 mA discharge and 1000 mA discharge.

For any of ZnO, Ca (OH) ₂ and Y ₂ O ₃ , the batteries F2 to F5, F8 to F11, and F14 to F17, whose addition amounts are 0.1 to 3 parts by weight, A high value was obtained for the capacity retention after storage at 60 ° C. In the batteries F1, F7, F13, and F19 in which the additive amount is less than 0.1 parts by weight, the self-discharge of nickel oxyhydroxide cannot be sufficiently suppressed, and the capacity retention rate after storage at 60 ° C. Decreased. In the batteries F6, F12, and F18 in which the additive amount was more than 3 parts by weight, the amount of the active material in the positive electrode mixture was relatively decreased, and the initial discharge performance was lowered.

Example 7
In this example, the amount of graphite added in the positive electrode mixture was examined. The same manganese dioxide and nickel oxyhydroxide as in Example 1 were mixed at a weight ratio of 1: 1. To this, 100 parts by weight of a mixture of manganese dioxide, nickel oxyhydroxide, and graphite was mixed in Table 8. Graphite was added so as to have the value shown in. This was mixed with 0.3 parts by weight of a polyethylene powder binder, 1 part by weight of ZnO powder and 1 part by weight of an electrolytic solution, and then uniformly stirred and mixed with a mixer to adjust the particle size to a constant particle size. And predetermined amount of the obtained granulated material was press-molded into a hollow cylindrical shape, and positive electrode mixtures G1 to G6 were obtained, respectively. In addition, the density of the obtained positive electrode mixture was about 3.3 g / cm ³ , and the porosity was 15 to 16%.

With respect to these positive electrode mixtures G1 to G6, the negative electrode theoretical capacity / positive electrode theoretical capacity value was 1.10, the porosity was 10%, and the electrolyte amount / negative electrode theoretical capacity value was about 1.2 cm ³ / Ah. Thus, alkaline dry batteries G1 to G6 were assembled in the same manner as in Example 1 except that the amount of gelled negative electrode and the amount of electrolyte injected into the battery can were adjusted.
About each battery obtained above, 50 mA discharge capacity and 1000 mA discharge capacity were measured by the same method as Example 4. Table 8 shows the measurement results. The discharge capacity in Table 8 was expressed as an index with the discharge capacity of the battery G3 as 100 in both cases of 50 mA discharge and 1000 mA discharge.

In the battery G1 in which the amount of graphite added is less than 3 parts by weight, the conductive network between the positive electrode active material particles in the positive electrode mixture is incomplete, and thus the discharge capacity is reduced particularly during 1000 mA (high load) discharge. In the battery G6 in which the amount of graphite added exceeds 10 parts by weight, the amount of the active material is relatively reduced, so that the discharge capacity is reduced particularly during 50 mA (low load) discharge.
From the above results, it was found that the addition amount of graphite in the positive electrode mixture is preferably 3 to 10 parts by weight with respect to 100 parts by weight of the mixture of manganese dioxide, nickel oxyhydroxide, and graphite.

In the above examples, nickel oxyhydroxide having a volume-based average particle diameter of 20 μm in which Mn is dissolved in a small amount and manganese dioxide having an average particle diameter of 40 μm are used. It is not limited to this.
In the above examples, ZnO, Ca (OH) ₂ , and Y ₂ O ₃ were added to the positive electrode mixture alone as additives, but two or more of these were added to the positive electrode mixture in combination. However, almost the same effect can be obtained.

  The alkaline dry battery of the present invention has a high capacity and is suitably used as a power source for digital devices and portable devices.

It is the front view which made a part of alkaline dry battery concerning the example of the present invention a section.

Explanation of symbols

71 Battery Can 72 Graphite Paint Film 73 Positive Electrode Mixture 74 Separator 75 Insulation Cap 76 Gel Negative Electrode 77 Resin Sealing Plate 78 Bottom Plate 79 Insulating Washer 70 Negative Electrode Current Collector 711 Exterior Label

Claims (7)

In the battery can, a hollow cylindrical positive electrode mixture, a gelled negative electrode containing zinc as an active material, a negative electrode current collector inserted into the negative electrode, a separator separating the positive electrode mixture and the gelled negative electrode, and An alkaline battery containing an electrolytic solution made of an alkaline aqueous solution,
The positive electrode mixture is made of manganese dioxide and nickel oxyhydroxide as an active material, graphite as a conductive agent, polyethylene powder as a binder, the electrolytic solution, and ZnO, Ca (OH) ₂ and Y ₂ O ₃ Including at least one selected additive,
The alkaline dry battery, wherein the density of the positive electrode mixture before injection of the electrolytic solution is 3.2 to 3.5 g / cm ³ and the porosity of the positive electrode mixture is 10 to 18%. . Furthermore, the alkaline dry battery of Claim 1 which satisfy | fills the following (1)-(3).
(1) The value of the theoretical capacity of the gelled negative electrode / the theoretical capacity of the positive electrode mixture is 1.00 to 1.15.
(2) Porosity in the battery can (the volume occupied by the positive electrode mixture, gelled negative electrode, separator, alkaline electrolyte, and negative electrode current collector from the volume in the battery can relative to the volume in the battery can) The ratio of the volume of the removed void portion) is 5 to 15%.
(3) The value of the theoretical amount of the electrolytic solution amount / the gelled negative electrode is 1.0 to 1.4 cm ³ / Ah.   The positive electrode mixture includes 10 to 80 parts by weight of the nickel oxyhydroxide and 85 to 15 parts by weight of the manganese dioxide with respect to 100 parts by weight of a mixture of manganese dioxide, nickel oxyhydroxide, and graphite. The alkaline dry battery according to 1 or 2.   3. The alkaline dry battery according to claim 1, wherein the positive electrode mixture contains 3 to 10 parts by weight of the graphite with respect to 100 parts by weight of a mixture of manganese dioxide, nickel oxyhydroxide, and graphite.   The alkaline dry battery according to claim 1 or 2, wherein the positive electrode mixture contains 0.1 to 1 part by weight of the polyethylene powder with respect to 100 parts by weight of a mixture of manganese dioxide, nickel oxyhydroxide, and graphite.   The alkaline dry battery according to claim 1 or 2, wherein the positive electrode mixture contains 0.1 to 3 parts by weight of the additive with respect to 100 parts by weight of a mixture of manganese dioxide, nickel oxyhydroxide, and graphite.   3. The alkaline dry battery according to claim 1, wherein the manganese dioxide has a volume-based average particle diameter of 30 to 50 μm and the nickel oxyhydroxide has a volume-based average particle diameter of 10 to 30 μm.

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