JP2005310752A - Alkaline battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To sufficiently use capacity of electrolytic manganese dioxide and nickel oxyhydroxide and to improve heavy load discharge characteristics in an alkaline battery. <P>SOLUTION: This alkaline battery is constructed of a positive electrode, a negative electrode, and an alkaline electrolyte. The positive electrode is formed of a positive electrode mix containing nickel oxyhydroxide, electrolytic manganese dioxide, and a graphite conducting agent. Nickel oxyhydroxide is formed of a β structure crystal dissolving manganese as a solid solution, and a content of manganese in the total sum of nickel and manganese included in nickel oxyhydroxide is 0.5-10 mol%. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an alkaline battery as a primary battery, and more particularly, to a so-called nickel manganese battery that employs an inside-out structure that includes manganese dioxide and nickel oxyhydroxide as active materials in a positive electrode mixture.

  The alkaline battery was disposed via a separator in the positive electrode case serving also as the positive electrode terminal, a positive electrode material mixture pellet made of cylindrical manganese dioxide arranged in close contact with the inside of the positive electrode case, and a positive electrode material mixture pellet. It has an inside-out structure comprising a gelled zinc negative electrode. The positive electrode mixture of an alkaline battery is generally composed of electrolytic manganese dioxide and a graphite conductive agent.

  With the spread of digital devices in recent years, the load power of devices using alkaline batteries has gradually increased, and there is a demand for a battery with excellent heavy load discharge performance. In order to cope with this, it has been proposed that nickel oxyhydroxide is mixed into the positive electrode mixture to improve the heavy load discharge characteristics of the battery (see Patent Document 1). In recent years, such alkaline batteries have been put into practical use and widely used.

  Nickel oxyhydroxide used for alkaline batteries is generally obtained by oxidizing spherical or hen egg-shaped nickel hydroxide for alkaline storage batteries with an oxidizing agent such as an aqueous sodium hypochlorite solution (see Patent Document 2). At this time, in order to achieve high-density filling in the battery, nickel hydroxide having a large bulk density (tap density) and comprising β-type structure crystals is used as a raw material. When such a raw material is treated with an oxidizing agent, nickel oxyhydroxide comprising β-type structure crystals can be obtained.

  For the purpose of increasing the positive electrode capacity of the battery or the utilization rate thereof, nickel hydroxide for alkaline storage batteries containing cobalt, zinc and the like may be used as a raw material (see Patent Document 3). In such nickel hydroxide crystals, cobalt, zinc, and the like are dissolved, and a solid solution of nickel hydroxide is formed.

In recent years, proposals using substantially spherical nickel oxyhydroxide for alkaline batteries (see Patent Document 4), proposals using solid solution nickel oxyhydroxide containing zinc or cobalt (see Patent Document 5), Proposal for controlling BET specific surface area (see Patent Document 6), proposal for controlling the amount of impurities such as sulfate radicals contained in nickel oxyhydroxide (see Patent Document 7), average particle diameter of nickel oxyhydroxide or electrolytic manganese dioxide There are some proposals (see Patent Document 8) for controlling the above. Any of these proposals can be regarded as a slide of a well-known technique related to a positive electrode of an alkaline storage battery (secondary battery) to a primary battery application.
JP-A-57-72266 Japanese Patent Publication No. 4-80513 Japanese Examined Patent Publication No. 7-77129 JP 2002-8650 A JP 2002-203546 A JP 2003-3213 A JP 2003-123745 A JP 2003-123747 A

  When nickel oxyhydroxide is added to the basic composition composed of electrolytic manganese dioxide and graphite conductive agent, the discharge voltage of the alkaline battery often has a two-stage discharge plateau region when the negative electrode contains zinc. The first plateau occurs near the battery voltage of about 1.6V, and the second plateau occurs at the battery voltage of about 1.25V. The discharge capacity of the first plateau region is mainly attributed to a discharge reaction in which nickel near 3.0 valence contained in nickel oxyhydroxide is reduced to a low oxidation state.

  On the other hand, it can be said that the larger the discharge capacity of the first plateau region, the more advantageous the battery capacity is. However, if all the nickel oxyhydroxide is discharged in the first plateau region until the nickel oxyhydroxide is reduced to near divalent, the electron conductivity of the nickel oxyhydroxide rapidly decreases, and the electron conductivity of the entire positive electrode mixture is reduced. The nature is also reduced. As a result, the capacity of electrolytic manganese dioxide that contributes to the discharge reaction mainly in the second plateau region cannot be fully utilized.

  Considering this point, it can be said that it is better not to completely discharge nickel oxyhydroxide in the first plateau region. It is preferable that the nickel oxyhydroxide has an appropriate residual capacity up to the second plateau region. By doing so, it is considered that the positive electrode mixture can maintain relatively high electronic conductivity even during the discharge of electrolytic manganese dioxide.

  However, in most cases, nickel oxyhydroxide used for alkaline storage batteries is directly converted to alkaline batteries from the viewpoint of raw material productivity, price, and the like. Therefore, material development focusing on the specific discharge mechanism as described above has not been made. For this reason, the case where the capacity | capacitance of the electrolytic manganese dioxide with which the battery was filled and nickel oxyhydroxide cannot fully be utilized arises.

  The present invention maintains the high electron conductivity of the positive electrode mixture even during the discharge of electrolytic manganese dioxide in the second plateau region, and fully utilizes the capacity of electrolytic manganese dioxide and nickel oxyhydroxide filled in the battery. One of the purposes is to do.

  Another object of the present invention is to provide an effective means for achieving both a further improvement in the heavy load discharge characteristics and an improvement in the utilization rate of electrolytic manganese dioxide.

  That is, the present invention comprises a positive electrode, a negative electrode and an alkaline electrolyte, the positive electrode comprises a positive electrode mixture containing nickel oxyhydroxide, electrolytic manganese dioxide and a graphite conductive agent, and nickel oxyhydroxide is a solid solution of manganese. The present invention relates to an alkaline battery comprising crystals of a β-type structure and having a manganese content of 0.5 to 10 mol% in the total amount of nickel and manganese contained in nickel oxyhydroxide.

  The present invention further provides an effective means for controlling the discharge capacity of nickel oxyhydroxide obtained in the second plateau region to an appropriate amount to achieve both higher battery capacity and improved utilization of electrolytic manganese dioxide. Is one of the purposes.

  For the above purpose, the present invention comprises a positive electrode, a negative electrode and an alkaline electrolyte, and the positive electrode comprises a positive electrode mixture comprising nickel oxyhydroxide, electrolytic manganese dioxide and a graphite conductive agent. An alkaline battery having the following characteristics is provided. That is, in the present invention, a molded body made of a mixture of the nickel oxyhydroxide and the graphite conductive agent is prepared, the molded body is immersed in an aqueous solution containing 40 wt% of KOH, and the molded body is nickel oxyhydroxide. When a constant current of 5 mA per gram is applied, the potential of the compact is as follows: the first plateau region of +500 to +100 mV for the Hg / HgO electrode and the second plateau of +100 to −400 mV for the Hg / HgO electrode The discharge capacity per gram of nickel oxyhydroxide in the first plateau region is 220 to 250 mAh, and the discharge capacity per gram of nickel oxyhydroxide in the second plateau region is 10 to 25 mAh. is there.

  According to the present invention, nickel oxyhydroxide does not completely discharge in the first plateau region, but has a suitable residual capacity up to the second plateau region. By doing so, the electron conductivity of the positive electrode mixture is maintained high even during the discharge of electrolytic manganese dioxide in the second plateau region. Therefore, the capacity of electrolytic manganese dioxide and nickel oxyhydroxide filled in the battery can be fully utilized.

  According to the present invention, not only can the capacities of electrolytic manganese dioxide and nickel oxyhydroxide be fully utilized, but also the heavy load discharge characteristics of the battery can be greatly enhanced.

  According to the present invention, by controlling the discharge capacity of the nickel oxyhydroxide obtained in the second plateau region to an appropriate amount, the discharge capacity of the first plateau region is sufficiently secured, and the current collection from the electrolytic manganese dioxide is performed. The sex can be enhanced sufficiently.

  The alkaline battery of the present invention comprises a positive electrode, a negative electrode and an alkaline electrolyte, and the positive electrode comprises a positive electrode mixture containing nickel oxyhydroxide, electrolytic manganese dioxide and a graphite conductive agent.

  When electrolytic manganese dioxide and nickel oxyhydroxide are compared, electrolytic manganese dioxide is superior in terms of capacity per unit weight (mAh / g), ease of filling in the case, material price, and the like. On the other hand, nickel oxyhydroxide is superior in terms of discharge voltage and heavy load discharge characteristics.

  Therefore, in consideration of the balance of battery characteristics and price, the content of nickel oxyhydroxide and electrolytic manganese dioxide in the total amount of nickel oxyhydroxide and electrolytic manganese dioxide contained in the positive electrode mixture is 10 to 80 wt%, respectively. And preferably 20 to 90 wt%. Further, from the viewpoint of obtaining a battery particularly excellent in the property balance, the contents of nickel oxyhydroxide and electrolytic manganese dioxide are more preferably 30 to 60 wt% and 40 to 70 wt%, respectively.

  The volume energy density of the active material in the positive electrode mixture is preferably higher. On the other hand, in order to ensure sufficient heavy load discharge characteristics, it is necessary to include a conductive agent made of graphite in the positive electrode mixture. From such a viewpoint, the content of the graphite conductive agent in the total amount of nickel oxyhydroxide, electrolytic manganese dioxide, and graphite conductive agent contained in the positive electrode mixture is preferably 3 to 10 wt%, and 5 to 8 wt%. % Is more preferable. When the content is less than 3 wt%, the electron conductivity of the whole positive electrode mixture may become insufficient regardless of the remaining capacity. On the other hand, if the content exceeds 10 wt%, the proportion of the active material in the positive electrode mixture may be too small, and the volume energy density of the active material may be insufficient.

  The nickel oxyhydroxide used for the positive electrode of the alkaline battery of the present invention is mixed with a graphite conductive agent, the mixture is molded, the resulting molded body is immersed in an aqueous solution containing 40 wt% KOH, and oxywater is added to the molded body. When a constant current of 5 mA per 1 g of nickel oxide is applied, the potential of the compact has a first plateau region that is a high potential region and a second plateau region that is a low potential region.

  The potential of the molded body is divided into, for example, a first plateau region of +500 to +100 mV with respect to the Hg / HgO electrode and a second plateau region of +100 to −400 mV with respect to the Hg / HgO electrode.

  It is desirable that the discharge capacity per gram of nickel oxyhydroxide in the first plateau region be regulated to 220 to 250 mAh / g. Further, it is desirable that the discharge capacity per gram of nickel oxyhydroxide in the second plateau region is regulated to 10 to 25 mAh.

  The discharge capacity of the first plateau region is mainly attributed to a discharge reaction in which nickel near 3.0 valence contained in nickel oxyhydroxide is reduced to a low oxidation state where the electron conductivity is reduced. Assuming that all of nickel oxyhydroxide has been reduced from about 3.0 to 2.1, the discharge capacity per gram of nickel oxyhydroxide obtained in the first plateau region is 260 mAh / The upper limit is about g.

  If the nickel oxyhydroxide has good electron conductivity and proton diffusivity, the discharge capacity per gram of nickel oxyhydroxide obtained in the first plateau region may actually exceed 250 mAh. In such a case, the nickel oxyhydroxide is completely discharged in the first plateau region, and the second plateau region has almost no capacity. Therefore, in the second plateau region where the electrolytic reaction of electrolytic manganese dioxide occurs, the decrease in the electron conductivity of the positive electrode mixture becomes remarkable, and the capacity cannot be taken out sufficiently.

  On the other hand, when the average valence of nickel in the nickel oxyhydroxide is low, or when the amount of Mn or the like dissolved in the nickel oxyhydroxide is excessive, the nickel oxyhydroxide obtained in the first plateau region The discharge capacity per gram may be less than 220 mAh. In that case, the discharge capacity of nickel oxyhydroxide is insufficient, and a high-capacity battery cannot be obtained.

  When nickel oxide or the like in a highly oxidized state is locally formed in nickel oxyhydroxide, it is assumed that the nickel oxide or the like in the highly oxidized state contributes to the discharge reaction in the second plateau region.

  Nickel oxyhydroxide containing a predetermined amount of nickel oxide or the like in a highly oxidized state as described above can suppress a decrease in electron conductivity even in the second plateau region. Therefore, a decrease in the electronic conductivity of the positive electrode mixture in the second plateau region is suppressed. As a result, the current collecting performance from electrolytic manganese dioxide is enhanced, and the capacity of the alkaline battery can be increased.

  However, when the discharge capacity per gram of nickel oxyhydroxide obtained in the second plateau region exceeds 25 mAh, the discharge capacity in the first plateau region relatively decreases to less than 220 mAh / g. On the other hand, when the discharge capacity per gram of nickel oxyhydroxide obtained in the second plateau region is less than 10 mAh, the amount of nickel oxide that contributes to the discharge reaction in the second plateau region is small. The effect of increasing becomes smaller.

  Nickel oxyhydroxide having desirable electrical characteristics as described above can be obtained relatively easily by dissolving a small amount of manganese in nickel oxyhydroxide. When manganese is dissolved in nickel oxyhydroxide, the heavy load discharge characteristics of the battery can be greatly improved. In particular, nickel oxyhydroxide composed of crystals having a β-type structure is excellent in that it has the above-described desirable electrical characteristics and has a small volume change during discharge.

  Even when a metal other than manganese is dissolved in nickel oxyhydroxide, a highly oxidized nickel oxide that contributes to the discharge reaction can be formed in the second plateau region. Examples of metals other than manganese include zinc, cobalt, aluminum, and chromium. However, the effect of enhancing the heavy load discharge characteristics of the battery becomes extremely remarkable when manganese is dissolved in nickel oxyhydroxide.

  In a preferred embodiment of the present invention, the nickel oxyhydroxide is composed of a β-type structure crystal in which manganese is dissolved. In such nickel oxyhydroxide particles, a highly oxidized nickel oxide that contributes to discharge is locally formed in the second plateau region having a low potential. That is, a part of the nickel oxyhydroxide composed of β-type crystals in which manganese is solid-dissolved contributes to the discharge in the low potential second plateau region. Therefore, even when the electrolytic manganese dioxide is discharged in the second plateau region, the electron conductivity of the positive electrode mixture is maintained high, and the capacity of the electrolytic manganese dioxide can be fully utilized. Furthermore, when manganese is dissolved in nickel oxyhydroxide, the heavy load discharge characteristics of the battery can be greatly improved.

  Nickel oxyhydroxide composed of β-type crystals in which manganese is dissolved is obtained, for example, by oxidizing nickel hydroxide in which manganese is dissolved in an oxidizing agent. The raw material nickel hydroxide is also preferably made of crystals having a β-type structure.

  In another preferred embodiment of the present invention, the nickel oxyhydroxide is composed of crystals in which a metal other than manganese is dissolved. Even in such nickel oxyhydroxide particles, a highly oxidized nickel oxide that contributes to discharge is locally formed in the second plateau region at a low potential. The nickel oxyhydroxide in which a metal other than manganese is solid-solved is also preferably composed of a β-type crystal.

  Nickel oxyhydroxide composed of crystals in which a metal other than manganese is dissolved is obtained, for example, by oxidizing nickel hydroxide in which a metal other than manganese is dissolved in an oxidizing agent. Also in this case, it is preferable to use nickel hydroxide made of crystals having a β-type structure as a raw material.

The particle shape of the raw material nickel hydroxide is not particularly limited, but is preferably spherical or egg-shaped. The tap density of nickel hydroxide is preferably 2.0 to 2.3 g / cm ³ , for example.

The BET specific surface area of the raw material nickel hydroxide is preferably 5 to ²⁰ m ² / g, for example.

  The sulfate radical concentration contained in the raw material nickel hydroxide is preferably 0.2 to 0.5% by weight, for example.

The volume-based average particle diameter (D ₅₀ ) of the raw material nickel hydroxide is preferably 10 to 20 μm.

  The raw material nickel hydroxide can be prepared, for example, in a reaction vessel equipped with a stirring blade. For example, pure water is added to the reaction vessel as a reaction phase in which nickel hydroxide grows. It is preferable to add a small amount of a reducing agent to the reaction phase, and it is preferable to perform bubbling with nitrogen gas.

  It is preferable to use manganese sulfate or a sulfate of a metal other than manganese and nickel sulfate as a starting material for the raw material nickel hydroxide. However, nickel nitrate or the like can be used instead of nickel sulfate, and manganese nitrate or the like can be used instead of manganese sulfate. Also, nitrates of metals other than manganese can be used instead of sulfates of metals other than manganese.

  Hereinafter, the preparation process of the nickel oxyhydroxide which consists of a crystal | crystallization of (beta) -type structure which solid-solved manganese is illustrated. The following method can also be applied to a process for preparing nickel oxyhydroxide comprising crystals in which a metal other than manganese is dissolved, if another metal salt is used instead of the manganese (II) sulfate aqueous solution.

  The preparation process of the raw material nickel hydroxide is performed by, for example, supplying a nickel (II) sulfate aqueous solution, a manganese (II) sulfate aqueous solution, a sodium hydroxide aqueous solution and aqueous ammonia to the reaction tank to maintain a constant pH of the reaction phase. While continuing the stirring. In this step, nickel hydroxide nuclei are precipitated in the reaction phase to grow nuclei. Subsequently, the obtained particles are heated in an aqueous sodium hydroxide solution different from the above to remove sulfate radicals. Thereafter, if the particles are washed with water and dried, raw material nickel hydroxide composed of crystals having a β-type structure is obtained.

  The step of preparing nickel oxyhydroxide includes, for example, a step of adding raw material nickel hydroxide into an aqueous sodium hydroxide solution as a reaction phase, adding a sufficient amount of oxidizing agent to the reaction phase, and stirring. In this step, the raw material nickel hydroxide is oxidized to obtain nickel oxyhydroxide.

  As an oxidizing agent for converting raw material nickel hydroxide into nickel oxyhydroxide, an aqueous sodium hypochlorite solution, an aqueous potassium peroxodisulfate solution, a hydrogen peroxide solution, or the like can be used.

The particle shape of the nickel oxyhydroxide depends on the raw material nickel hydroxide, but is preferably spherical or egg-shaped. The tap density of nickel oxyhydroxide is preferably, for example, 2.1 to 2.4 g / cm ³ .

The BET specific surface area of nickel oxyhydroxide is preferably, for example, 10 to 20 m ² / g.

  The sulfate radical concentration contained in nickel oxyhydroxide is preferably, for example, 0.1 to 0.3% by weight.

The volume-based average particle diameter (D ₅₀ ) of nickel oxyhydroxide is preferably 10 to 20 μm.

  The content of manganese in the total amount of nickel and manganese contained in nickel oxyhydroxide is, for example, 0.5 to 10 mol%, and preferably 2 to 7 mol%. When the manganese content is less than 0.5 mol%, the discharge capacity of the second plateau region is too small. When the manganese content exceeds 10 mol%, the discharge capacity of the second plateau region becomes excessive, and the discharge capacity of the first plateau region is too high. Run short.

  The content of metal M in the total amount of nickel and metal other than manganese (hereinafter, metal M) contained in nickel oxyhydroxide is, for example, 0.5 to 10 mol%, and 2 to 5 mol%. preferable. When the metal M content is less than 0.5 mol%, the discharge capacity of the second plateau region may be too small. When the content exceeds 10 mol%, the discharge capacity of the second plateau region becomes excessive, and the first plateau region becomes excessive. The discharge capacity of the area may be insufficient.

The positive electrode mixture preferably further contains at least one rare earth metal oxide selected from the group consisting of Y ₂ O ₃ , Er ₂ O ₃ , Tm ₂ O ₃ , Yb ₂ O ₃ and Lu ₂ O _3. . These rare earth metal oxides are slightly dissolved in the alkaline electrolyte to form hydroxides and reprecipitate. As a result, a film containing a rare earth metal is formed on the surface of the nickel oxyhydroxide particles. This film has a role of increasing the oxygen generation overvoltage of the positive electrode.

  Nickel oxyhydroxide comprising β-type crystals in which manganese is solid-solved has a noble equilibrium potential. For this reason, the open circuit voltage of the battery is kept relatively high, and the self-discharge rate tends to increase. Therefore, adding a small amount of rare earth metal oxide to the positive electrode mixture leads to a significant improvement in the storage characteristics of the battery.

  The content of the rare earth metal oxide in the total of nickel oxyhydroxide, electrolytic manganese dioxide, graphite conductive agent and rare earth metal oxide is preferably 0.1 to 2 wt%, and 0.5 to 1.5 wt% More preferably.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to a following example.

(Preparation of raw material nickel hydroxide)
While adding pure water and a small amount of hydrazine as a reducing agent to a reaction vessel equipped with a stirring blade, and bubbling with nitrogen gas in the vessel, a nickel (II) sulfate aqueous solution, a manganese (II) sulfate aqueous solution of a predetermined concentration, Sodium hydroxide aqueous solution and aqueous ammonia were quantitatively supplied by a pump. Meanwhile, stirring in the tank was continued to maintain the pH constant. After that, nickel hydroxide nuclei were precipitated and nuclei were grown by sufficiently continuing the stirring in the tank. Subsequently, the obtained particles were heated in a sodium hydroxide aqueous solution different from the above to remove sulfate radicals. Thereafter, the particles were washed with water and vacuum-dried to obtain raw material nickel hydroxide a (composition: Ni _0.95 Mn _0.05 (OH) ₂ ).

Next, nickel hydroxide b (composition: Ni _0.95 Zn _0.05 (composition) was carried out in the same manner as above except that an aqueous solution of zinc (II) sulfate was used instead of the aqueous solution of manganese (II) sulfate. OH) ₂ ) was obtained.

  Furthermore, the same operation as described above was performed except that manganese (II) sulfate or zinc sulfate (II) aqueous solution was not used, and nickel hydroxide c containing no metal other than nickel was obtained.

It was confirmed by powder X-ray diffraction measurement that the obtained raw material nickel hydroxides a to c were each composed of a β-type crystal. The raw material nickel hydroxides a to c all had the following physical properties.
Volume-based average particle diameter: about 20 μm
Tap density (number of tapping: 300 times): about 2.2 g / cm ³
BET specific surface area: about 10 m ² / g

(Preparation of nickel oxyhydroxide)
200 g of nickel hydroxide a was put in 1 L of a 0.1 mol / L sodium hydroxide aqueous solution, and a sufficient amount of an oxidizing agent sodium hypochlorite aqueous solution (effective chlorine concentration: 10 wt%) was added and stirred. Converted to nickel oxide. The obtained particles were sufficiently washed with water and then vacuum-dried at 60 ° C. for 24 hours to obtain nickel oxyhydroxide A.

  The same operations as described above were performed on the raw material nickel hydroxides b and c to obtain nickel oxyhydroxides B and C, respectively.

It was confirmed by powder X-ray diffraction measurement that the obtained nickel oxyhydroxides A to C were each made of a crystal having a β-type structure. Moreover, all of the nickel oxyhydroxides A to C had the following physical properties.
Volume-based average particle diameter: about 20 μm
Tap density (number of tapping: 300 times): about 2.3 g / cm ³
BET specific surface area: about 12 m ² / g

(Preparation of positive electrode mixture pellets)
Electrolytic manganese dioxide, nickel oxyhydroxide A, and graphite were blended at a weight ratio of 50: 45: 5 and mixed to obtain a positive electrode mixture powder. After adding 1 part by weight of the alkaline electrolyte per 100 parts by weight of the positive electrode mixture powder, the positive electrode mixture powder was stirred with a mixer, mixed until uniform, and sized to a constant particle size. In addition, 40 weight% aqueous solution of potassium hydroxide was used for alkaline electrolyte. The obtained granular material was press-molded into a hollow cylindrical shape to obtain a positive electrode material mixture pellet A.

  Moreover, the same operation as described above was performed using nickel oxyhydroxides B and C to obtain positive electrode mixture pellets B and C, respectively.

(Production of nickel manganese battery)
AA size nickel manganese batteries A1, B1, and C1 were respectively produced using the positive electrode mixture pellets A, B, and C described above. FIG. 1 is a front view showing a cross section of a part of the nickel manganese battery produced here.

  For the positive electrode case 1 that also serves as the positive electrode terminal, a can-shaped case made of a nickel-plated steel plate was used. A graphite coating film 2 was formed on the inner surface of the positive electrode case 1. A plurality of short cylindrical positive electrode mixture pellets 3 were inserted into the positive electrode case 1. Next, the positive electrode material mixture pellet 3 was re-pressurized in the positive electrode case 1 and adhered to the inner surface of the positive electrode case 1. A separator 4 was inserted into the hollow of the positive electrode mixture pellet 3 and brought into contact with the hollow inner surface. An insulating cap 5 was disposed at the bottom of the hollow can-like case.

  Next, an alkaline electrolyte was injected into the positive electrode case 1 to wet the positive electrode mixture pellet 3 and the separator 4. After injecting the electrolyte, the gelled negative electrode 6 was filled inside the separator 4. The gelled negative electrode 6 was made of sodium polyacrylate as a gelling agent, an alkaline electrolyte, and zinc powder as a negative electrode active material. A 40% by weight aqueous solution of potassium hydroxide was used as the alkaline electrolyte.

  On the other hand, a resin sealing plate 7 having a short cylindrical center part and a thin outer peripheral part and having an inner groove at the peripheral edge of the outer peripheral part was prepared. In the inner groove at the peripheral edge of the sealing plate 7, the peripheral edge of the bottom plate 8 serving also as the negative electrode terminal was fitted. An insulating washer 9 was interposed between the sealing plate 7 and the bottom plate 8. A nail-like negative electrode current collector 10 was inserted into the hollow at the center of the sealing plate 7.

  The negative electrode current collector 10 previously integrated with the sealing plate 7, the bottom plate 8 and the insulating washer 9 as described above was inserted into the gelled negative electrode 6. Next, the opening end of the positive electrode case 1 was caulked to the peripheral edge of the bottom plate 8 via the peripheral edge of the sealing plate 7, and the opening of the positive electrode case 1 was sealed. Finally, the outer surface of the positive electrode case 1 was covered with an exterior label 11 to complete a nickel manganese battery.

(Production of model cell)
In order to obtain knowledge about the electrical characteristics of nickel oxyhydroxide alone, a model cell having a structure similar to that of the above nickel manganese battery was produced.
Nickel oxyhydroxide A and graphite were blended at a weight ratio of 92: 8 and mixed to obtain a model mixture powder. After adding 1 part by weight of the alkaline electrolyte per 100 parts by weight of the model mixture powder, the model mixture powder was stirred with a mixer, mixed until uniform, and sized to a constant particle size. In addition, 40 weight% aqueous solution of potassium hydroxide was used for alkaline electrolyte. The obtained granular material was press-molded into a hollow cylindrical shape to obtain a model mixture pellet A.

  A model cell A2 similar to the AA alkaline battery shown in FIG. 1 was assembled by performing the same operation as described above except that the model mixture pellet A was used. The amount of nickel oxyhydroxide (NiOOH) contained in the model cell was 9.0 g, and the model cell was filled with a sufficient amount of gelled negative electrode.

  In addition, the same operation as described above was performed using nickel oxyhydroxides B and C to produce model mixture pellets B and C, respectively, and then model cells B2 and C2 were assembled.

  Nickel leads for collecting current were welded to the positive electrode terminal and the negative electrode terminal of each model cell. Next, a hole was made in the end portion of the positive electrode case and immersed in a beaker filled with a 40 wt% aqueous solution of potassium hydroxide. In the beaker, an Hg / HgO electrode was immersed as a reference electrode. Thus, preparation was made to measure the potentials of the positive electrode and the negative electrode of the model cell with respect to the Hg / HgO electrode, respectively. All model cells are regulated by positive electrode capacity. According to the measuring apparatus including the model cell, it is possible to observe the discharge characteristics of the positive electrode basically composed of nickel oxyhydroxide alone that does not contain electrolytic manganese dioxide.

(Evaluation of nickel manganese battery)
<Low load discharge characteristics>
The initial nickel manganese batteries A1 to C1 were each continuously discharged at 20 ° C. with a constant current of 45 mA (low load), and the discharge capacity until the battery voltage reached 0.9 V was measured. The discharge curve at this time is shown in FIG.

<High load discharge characteristics>
The initial nickel manganese batteries A1 to C1 were each continuously discharged at a constant power of 1 W at 20 ° C., and the discharge time until the battery voltage reached a final voltage of 0.9 V was measured.

  The discharge capacity in the low load discharge and the discharge time in the heavy load discharge obtained for the nickel manganese battery C1 are each set as a reference value 100, and the results obtained for each battery are shown in Table 1 as relative values to the nickel manganese battery C1.

  From Table 1, the nickel manganese battery A1 using nickel oxyhydroxide (nickel oxyhydroxide A) composed of β-type structure crystals in which manganese is solid-dissolved has excellent characteristics in both low load discharge and high load discharge. It can be seen that

In the discharge curve of FIG. 2, the voltage range near 1.6V is a region where the discharge reaction of nickel oxyhydroxide proceeds mainly, and the voltage range near 1.2V is mainly the discharge reaction of electrolytic manganese dioxide. It is an area that progresses.
As apparent from FIG. 2, the capacity difference between the batteries caused by the low load discharge is lower than the region where the discharge reaction of nickel oxyhydroxide mainly proceeds, and the discharge reaction of electrolytic manganese dioxide mainly proceeds. This is noticeable in the voltage side region.

(Model cell evaluation)
In order to further consider the evaluation results of the nickel manganese battery, the above-described model cells A2 to C2 were each continuously discharged at a constant current of 45 mA at 20 ° C. (that is, a constant current of 5 mA per 1 g of nickel oxyhydroxide). FIG. 3 shows a potential curve showing the relationship between the positive electrode potential with respect to the Hg / HgO electrode and the discharge capacity per gram of nickel oxyhydroxide obtained at that time.

  In FIG. 3, two-stage plateaus are observed in the positive electrode potential curves of model cell A2 using nickel oxyhydroxide A and model cell B2 using nickel oxyhydroxide B, respectively. The first plateau is observed in the +500 to +100 mV region with respect to the Hg / HgO electrode. The second plateau is observed in the region of +100 to −400 mV with respect to the Hg / HgO electrode.

  However, the capacity of the first plateau region of the model cell B2 is considerably smaller than the capacity of the first plateau region of the model cell A2. Conversely, the capacity of the second plateau region of the model cell B2 is larger than the capacity of the second plateau region of the model cell A2.

  On the other hand, in the potential curve of the positive electrode of model cell C2 using nickel oxyhydroxide C, the capacity of the first plateau region is the largest, but the second plateau region is not recognized.

  Considering the evaluation result of such a positive electrode made of nickel oxyhydroxide alone, the behavior during low load discharge (FIG. 2) obtained by the evaluation of the nickel manganese battery can be understood as follows.

  As shown in FIG. 3, the nickel oxyhydroxide C is completely discharged to near the valence of 2 only in the first plateau region. Therefore, the electronic conductivity of nickel oxyhydroxide C rapidly decreases in the second plateau region of +100 to −400 mV with respect to the Hg / HgO electrode. Similarly, in the nickel manganese battery C1, the electronic conductivity of the whole positive electrode mixture is reduced in the second plateau region. As a result, it is difficult to sufficiently extract the capacity from the electrolytic manganese dioxide that mainly discharges in the second plateau region.

  On the other hand, the discharge capacity of the first plateau region of nickel oxyhydroxide B is considerably reduced as shown in FIG. Therefore, in the nickel manganese battery B1, the discharge capacity in the first plateau region is insufficient, and eventually a high capacity battery cannot be obtained.

  However, the discharge capacity of the first plateau region of nickel oxyhydroxide A is relatively large, and the second plateau region also has an appropriate amount of remaining capacity. Therefore, the nickel manganese battery A1 does not have a short discharge capacity in the first plateau region, and the positive electrode mixture can maintain high electron conductivity even in the second plateau region. Therefore, a sufficient capacity can be taken out from the electrolytic manganese dioxide in the second plateau region.

  For the above reasons, the nickel manganese battery A1 is considered to have given the highest discharge capacity. Thus, according to the present invention, the capacity of the alkaline battery can be increased efficiently.

  As described above, in the first plateau region, a normal nickel oxyhydroxide discharge capacity is obtained, and in the second plateau region, a highly oxidized nickel oxide locally formed by solid solution of different elements. It is thought that the discharge capacity by etc. is obtained.

  In particular, nickel oxyhydroxide in which manganese was dissolved as a different element had specificity and gave a preferable potential curve similar to that of the model cell A2 within a wide manganese content range of 0.5 to 10 mol%.

  In Table 1, extremely excellent heavy load discharge characteristics are obtained in the nickel manganese battery A1 using the nickel oxyhydroxide A in which manganese is dissolved. This is because when manganese is dissolved in nickel oxyhydroxide crystals, compared with the case where another element such as zinc is dissolved, a high oxidation state locally formed in nickel oxyhydroxide. This is thought to be due to the excellent proton diffusibility and electronic conductivity of the nickel oxide. Thus, from the viewpoint of improving the heavy load discharge characteristics, nickel oxyhydroxide in which manganese is dissolved is most excellent.

(Production of raw material nickel hydroxide)
The following raw material nickel hydroxide was obtained in the same manner as in Example 1 except that the ratio between the supply amount of the nickel (II) sulfate aqueous solution and the supply amount of the manganese (II) sulfate aqueous solution was changed.
Raw material nickel hydroxide d (composition: Ni _0.97 Mn _0.03 (OH) ₂ )
Raw material nickel hydroxide e (composition: Ni _0.94 Mn _0.06 (OH) ₂ )
Raw material nickel hydroxide f (composition: Ni _0.91 Mn _0.09 (OH) ₂ )

Next, the same operation as described above was performed except that a zinc (II) sulfate aqueous solution was used instead of the manganese (II) sulfate aqueous solution, and the following raw material nickel hydroxide was obtained.
Raw material nickel hydroxide g (composition: Ni _0.97 Zn _0.03 (OH) ₂ )
Raw material nickel hydroxide h (composition: Ni _0.94 Zn _0.06 (OH) ₂ )
Raw material nickel hydroxide i (composition: Ni _0.91 Zn _0.09 (OH) ₂ )

Further, the same raw material nickel hydroxide was obtained as described above, except that a zinc (II) sulfate aqueous solution and a cobalt sulfate aqueous solution were used in combination instead of the manganese sulfate (II) aqueous solution. .
Raw material nickel hydroxide j (composition: Ni _0.96 Zn _0.03 Co _0.01 (OH) ₂ )
Raw material nickel hydroxide k (composition: Ni _0.93 Zn _0.06 Co _0.01 (OH) ₂ )
Raw material nickel hydroxide l (composition: Ni _0.90 Zn _0.09 Co _0.01 (OH) ₂ )

It was confirmed by powder X-ray diffraction measurement that the obtained raw material nickel hydroxides d to l were each composed of crystals having a β-type structure. In addition, nickel hydroxides d to l all had the following physical properties.
Volume-based average particle diameter: about 20 μm
Tap density (number of tapping: 300 times): about 2.2 g / cm ³
BET specific surface area: about 10 m ² / g

(Preparation of nickel oxyhydroxide)
The raw material nickel hydroxides d to l were oxidized in the same manner as in Example 1 and converted to nickel oxyhydroxides D to L.
It was confirmed by powder X-ray diffraction measurement that the obtained nickel oxyhydroxides D to L were each made of a crystal having a β-type structure. Moreover, all the nickel oxyhydroxides D to L had the following physical properties.
Volume-based average particle diameter: about 20 μm
Tap density (number of tapping: 300 times): about 2.3 g / cm ³
BET specific surface area: about 12 m ² / g

(Preparation of positive electrode mixture pellets)
Except having used nickel oxyhydroxide D-L, operation similar to Example 1 was performed and the positive electrode mixture pellets D-L were obtained, respectively.

(Production of nickel manganese battery)
Except having used said positive electrode mixture pellets D-L, operation similar to Example 1 was performed and the AA size nickel manganese battery D1-L1 was produced, respectively.

(Production of model cell)
In order to obtain knowledge about the electrical characteristics of nickel oxyhydroxide alone, a model cell similar to that in Example 1 was produced. That is, nickel oxyhydroxide and graphite were blended at a weight ratio of 92: 8, and the same operation as in Example 1 was performed to obtain model mixture pellets D to L. And the model cells D2-L2 similar to Example 1 were assembled using the model mixture pellets D-L. Further, similarly to Example 1, a measuring apparatus including a model cell for observing the discharge characteristics of the positive electrode was assembled.

(Model cell evaluation)
The above model cells D2 to L2 were each continuously discharged at 20 ° C. with a constant current of 45 mA (that is, a constant current of 5 mA per 1 g of nickel oxyhydroxide). Table 2 collectively shows the discharge capacities obtained in the first plateau region of +500 to +100 mV and the second plateau region of +100 to −400 mV with respect to the Hg / HgO electrode.

  Note that a two-stage plateau was clearly observed in the positive electrode potential curves of the model cells D2 to L2. Further, when the content of the dissimilar metal contained in the nickel oxyhydroxide is increased, the discharge capacity of the first plateau region on the high potential side tends to decrease and the discharge capacity of the second plateau region on the low potential side tends to increase. .

(Evaluation of nickel manganese battery)
<Low load discharge characteristics>
The initial nickel manganese batteries D1 to L1 were each continuously discharged at 20 ° C. with a constant current of 45 mA, and the discharge capacity until the battery voltage reached 0.9V was measured.

<High load discharge characteristics>
The initial nickel manganese batteries D1 to L1 were each continuously discharged at a constant power of 1 W at 20 ° C., and the discharge time until the battery voltage reached a final voltage of 0.9 V was measured.

  The discharge capacity in the low load discharge and the discharge time in the heavy load discharge obtained for the nickel manganese battery C1 of Example 1 are set as reference values 100, respectively, and the results obtained for each battery are expressed as relative values with respect to the nickel manganese battery C1. 3 shows.

  In Table 2, the positive electrodes of the model cells D2, E2, F2, G2, and J2 all have a discharge capacity of 220 mAh / g or more in the first plateau region, and a discharge capacity of 10 to 25 mAh / g in the second plateau region. Have Table 3 shows that the discharge capacity at low load discharge is improved by 3 to 8% in the nickel manganese batteries D1, E1, F1, G1 and J1 over the nickel manganese battery C1.

  Such improvement in low-load discharge characteristics is based on the fact that nickel oxyhydroxides D, E, F, G, and J have a discharge capacity of an appropriate size in the first plateau region. Second, since nickel oxyhydroxides D, E, F, G, and J also have a suitable residual capacity in the second plateau region, the electron conductivity of the positive electrode mixture is maintained during the discharge of electrolytic manganese dioxide. It is based on the improved utilization of electrolytic manganese dioxide.

  On the other hand, the positive electrodes of the model cells H2, I2, K2, and L2 all have insufficient discharge capacity in the first plateau region, and as a result, no increase in battery capacity has been achieved.

  Further, the heavy load discharge characteristics are remarkably improved in nickel manganese batteries D1, E1 and F1 using nickel oxyhydroxides D, E and F in which manganese is dissolved. The reason for this difference is that nickel oxide in a highly oxidized state produced by dissolving manganese in solid crystals of nickel oxyhydroxide is a highly oxidized state produced by a dissimilar metal such as Zn or Co. This is presumably because the proton diffusibility and electron conductivity are superior to those of nickel oxide.

  Except that the content of manganese in the total of nickel and manganese contained in nickel oxyhydroxide was changed as shown in Table 4 in the following manner, the same operation as in Example 1 was performed, respectively. Positive electrode mixture pellets M1 to M7 were obtained.

(Preparation of raw material nickel hydroxide)
The following raw material nickel hydroxide was obtained in the same manner as in Example 1 except that the ratio between the supply amount of the nickel (II) sulfate aqueous solution and the supply amount of the manganese (II) sulfate aqueous solution was changed.

Raw material nickel hydroxide m1 (composition: Ni _0.999 Mn _0.001 (OH) ₂ )
Raw material nickel hydroxide m2 (composition: Ni _0.995 Mn _0.005 (OH) ₂ )
Raw material nickel hydroxide m3 (composition: Ni _0.99 Mn _0.01 (OH) ₂ )
Raw material nickel hydroxide m4 (composition: Ni _0.96 Mn _0.04 (OH) ₂ )
Raw material nickel hydroxide m5 (composition: Ni _0.93 Mn _0.07 (OH) ₂ )
Raw material nickel hydroxide m6 (composition: Ni _0.9 Mn _0.1 (OH) ₂ )
Raw material nickel hydroxide m7 (composition: Ni _0.88 Mn _0.12 (OH) ₂ )

It was confirmed by powder X-ray diffraction measurement that the obtained raw material nickel hydroxides m1 to m7 were each composed of a β-type crystal. Moreover, all of the nickel hydroxides m1 to m7 had the following physical properties.
Volume-based average particle size: 15-20 μm
Tap density (number of tapping: 300 times): 2.1 to 2.2 g / cm ³
BET specific surface area: 8-12 m ² / g

(Preparation of nickel oxyhydroxide)
The raw material nickel hydroxides m1 to m7 were oxidized in the same manner as in Example 1 and converted to nickel oxyhydroxides M1 to M7.
It was confirmed by powder X-ray diffraction measurement that the obtained nickel oxyhydroxides M1 to M7 were each made of a crystal having a β-type structure. Moreover, each of the nickel oxyhydroxides M1 to M7 had the following physical properties.
Volume-based average particle size: 15-20 μm
Tap density (number of tapping: 300 times): 2.2 to 2.3 g / cm ³
BET specific surface area: about 10 to 14 m ² / g

(Preparation of positive electrode mixture pellets)
Except having used nickel oxyhydroxide M1-M7, operation similar to Example 1 was performed and the positive electrode mixture pellets M1-M7 were obtained, respectively. Except having used the obtained positive mix pellets M1-M7, operation similar to Example 1 was performed and the AA size nickel manganese batteries M1-M7 were produced, respectively.

(Evaluation of nickel manganese battery)
<Low load discharge characteristics>
First nickel manganese batteries M1 to M7 were each continuously discharged at a constant current of 45 mA at 20 ° C., and the discharge capacity until the battery voltage reached 0.9 V was measured.

<High load discharge characteristics>
First nickel manganese batteries M1 to M7 were each continuously discharged at a constant power of 1 W at 20 ° C., and the discharge time until the battery voltage reached a final voltage of 0.9 V was measured.

  The discharge capacity in the low load discharge and the discharge time in the heavy load discharge obtained for the nickel manganese battery C1 of Example 1 are set as reference values 100, respectively, and the results obtained for each battery are expressed as relative values with respect to the nickel manganese battery C1. 4 shows.

  From Table 4, it can be seen that the effect of increasing the capacity can be obtained at the time of low load and high load discharge of the nickel manganese battery in a wide manganese content range of 0.5 to 10 mol%.

(Production of nickel manganese battery)
In preparation of the positive electrode mixture pellets, electrolytic manganese dioxide, nickel oxyhydroxide A, graphite, and oxide additive were blended in a weight ratio of 49: 45: 5: 1 and mixed to obtain a positive electrode. Except for obtaining the mixture powder, the same battery as the nickel manganese battery A1 of Example 1 was produced and evaluated. And the effect by an oxide additive was examined.

Yttrium oxide (Y ₂ O ₃ ), erbium oxide (Er ₂ O ₃ ), thulium oxide (Tm ₂ O ₃ ), ytterbium oxide (Yb ₂ O ₃ ), lutetium oxide (Lu ₂ O ₃ ) and oxide additives The batteries using zinc oxide (ZnO) were named nickel manganese batteries P, Q, R, S, T, and U, respectively. On the other hand, a battery produced by the same operation as described above except that no oxide additive was used was designated as a nickel manganese battery V.

(Evaluation of nickel manganese battery)
<Low load discharge characteristics>
The initial nickel manganese batteries P to V were each continuously discharged at 20 ° C. with a constant current of 45 mA, and the discharge capacity until the battery voltage reached 0.9 V was measured.

<Storage characteristics>
The nickel manganese batteries P to V after storage at 60 ° C. for 1 week were continuously discharged at 20 ° C. with a constant current of 45 mA, and the discharge capacity until the battery voltage reached a final voltage of 0.9 V was measured.

  The discharge capacity at low load discharge obtained for the first nickel manganese battery V is defined as a reference value 100, and the results obtained for each battery are shown in Table 5 as relative values with respect to the first nickel manganese battery V.

  From Table 5, even when a rare earth metal oxide (any one of yttrium oxide, erbium oxide, thulium oxide, ytterbium oxide, and lutetium oxide) is included in the positive electrode mixture, the discharge capacity of the first battery is determined by adding the oxide It can be seen that there is almost no difference from the nickel manganese battery V which does not use an agent.

  On the other hand, it can be seen that the capacity of the battery after storage for 1 week at 60 ° C. is very excellent in the batteries P to T using rare earth metal oxides. The rare earth metal oxide is considered to dissolve slightly in the alkaline electrolyte to form a hydroxide, and re-deposit on the surface of the nickel oxyhydroxide particles to form a coating. As a result, it is surmised that the oxygen generation overvoltage of the positive electrode is increased and the self-discharge reaction is suppressed.

  Nickel oxyhydroxide comprising β-type crystals in which manganese is solid-solved has a noble equilibrium potential. For this reason, the open circuit voltage of the battery is kept relatively high, and the self-discharge rate tends to increase. Therefore, the addition of the rare earth metal oxide to the positive electrode mixture is particularly effective in improving the storage characteristics of the battery using nickel oxyhydroxide comprising β-type crystals in which manganese is dissolved.

(Production of nickel manganese battery)
In the preparation of the positive electrode mixture pellet, the weight ratio of nickel oxyhydroxide A and electrolytic manganese dioxide was changed as shown in Table 6, and a total of 95 parts by weight of nickel oxyhydroxide A and electrolytic manganese dioxide and graphite conductive The same batteries W1 to W8 as the nickel manganese battery A1 of Example 1 were prepared and evaluated, except that 5 parts by weight of the agent was mixed to obtain a positive electrode mixture powder.

(Evaluation of nickel manganese battery)
<Low load discharge characteristics>
The initial nickel manganese batteries W1 to W8 were each continuously discharged at a constant current of 45 mA at 20 ° C., and the discharge capacity until the battery voltage reached 0.9 V was measured.

<High load discharge characteristics>
The initial nickel manganese batteries W1 to W8 were each continuously discharged at a constant power of 1 W at 20 ° C., and the discharge time until the battery voltage reached a final voltage of 0.9 V was measured.

  The discharge capacity in the low load discharge and the discharge time in the heavy load discharge obtained for the nickel manganese battery C1 of Example 1 are each set as a reference value 100, and the results obtained in each battery are expressed as relative values with respect to the nickel manganese battery C1. It is shown in FIG.

  From Table 6, considering the balance of battery characteristics, the content of nickel oxyhydroxide in the total amount of nickel oxyhydroxide and electrolytic manganese dioxide is 10 to 80 wt%, and the electrolytic manganese dioxide in the total amount It can be understood that the content of is preferably 20 to 90 wt%.

(Production of nickel manganese battery)
In the preparation of the positive electrode mixture pellet, the weight ratio of nickel oxyhydroxide A and electrolytic manganese dioxide was changed to 50:50, and the graphite conductive agent in the total of nickel oxyhydroxide A, electrolytic manganese dioxide and graphite conductive agent The same batteries X1 to X4 as the nickel-manganese battery A1 of Example 1 were prepared and evaluated, except that the positive electrode material mixture powder was obtained by changing the content ratio of As shown in Table 7.

(Evaluation of nickel manganese battery)
<Low load discharge characteristics>
The initial nickel manganese batteries X1 to X4 were each continuously discharged at a constant current of 45 mA at 20 ° C., and the discharge capacity until the battery voltage reached 0.9 V was measured.

<High load discharge characteristics>
The initial nickel manganese batteries X1 to X4 were each continuously discharged at a constant power of 1 W at 20 ° C., and the discharge time until the battery voltage reached a final voltage of 0.9 V was measured.

  The discharge capacity in the low load discharge and the discharge time in the heavy load discharge obtained for the nickel manganese battery C1 of Example 1 are each set as a reference value 100, and the results obtained in each battery are expressed as relative values with respect to the nickel manganese battery C1. 7 shows.

  From Table 7, it can be understood that the content of the graphite conductive agent in the total amount of nickel oxyhydroxide, electrolytic manganese dioxide, and the graphite conductive agent is preferably 3 to 10 wt% in consideration of the balance of battery characteristics.

(Production of nickel manganese battery)
In the preparation of the positive electrode mixture pellets, electrolytic manganese dioxide, nickel oxyhydroxide A and graphite conductive agent are blended in a weight ratio of 49: 45: 5, and Y ₂ O ₃ is blended. except that to obtain a positive electrode mixture powder by changing the content of Y ₂ O ₃ in the total of the a and the electrolytic manganese dioxide and graphite conductive agent, and Y ₂ O ₃ as described in Table 8 of example 1 The same batteries Y1 to Y5 as the nickel manganese battery A1 were produced and evaluated.

(Evaluation of nickel manganese battery)
<Low load discharge characteristics>
The initial nickel manganese batteries Y1 to Y5 were each continuously discharged at 20 ° C. with a constant current of 45 mA, and the discharge capacity until the battery voltage reached 0.9V was measured.

<Storage characteristics>
The nickel manganese batteries Y1 to Y5 after storage at 60 ° C. for 1 week were each continuously discharged at 20 ° C. with a constant current of 45 mA, and the discharge capacity until the battery voltage reached a final voltage of 0.9 V was measured.

  The discharge capacity at low load discharge obtained for the initial nickel manganese battery V of Example 4 is defined as a reference value 100, and the results obtained for each battery are shown in Table 8 as relative values to the initial nickel manganese battery V.

From Table 8, it can be seen that even when Y ₂ O ₃ is contained at a ratio of 0.1 to ₂ wt% of the entire positive electrode mixture, the storage characteristics of almost the same level as the nickel manganese battery P of Example 4 can be obtained. Understand. Moreover, it is speculated that the same applies to other rare earth metal oxides. Although the details are not shown here, they have been actually confirmed.

In all of the above examples, the volume-based average particle size is 15 to 20 μm, the tap density (number of tapping: 300 times) is 2.2 to 2.3 g / cm ³ , and the BET specific surface area is about 10 to 14 m ^2. / G of nickel oxyhydroxide was used, but the present invention does not require these powder properties. Nickel oxyhydroxide having powder properties other than those described above can also be used in the present invention.

  Further, in the above embodiment, an alkaline battery having a so-called inside-out type structure was produced, but the present invention can also be applied to batteries having other structures such as a button type and a square type.

  As described above, according to the present invention, it is possible to efficiently increase the capacity of an alkaline battery and to expect an improvement in heavy load discharge characteristics. Therefore, the industrial value is very large. The present invention can be applied to an alkaline battery as a primary battery, and is particularly effective in a nickel manganese battery.

It is the front view which made some cross sections the nickel manganese battery which concerns on the Example of this invention. 2 is a discharge curve of nickel manganese batteries A1 to C1 according to Example 1. FIG. 3 is a potential curve of positive electrodes of model cells A2 to C2 according to Example 1;

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Positive electrode case 2 Graphite coating film 3 Positive electrode mixture pellet 4 Separator 5 Insulation cap 6 Gel-like negative electrode 7 Sealing plate 8 Bottom plate 9 Insulating washer 10 Negative electrode current collector 11 Exterior label

Claims (5)

Consisting of positive electrode, negative electrode and alkaline electrolyte,
The positive electrode comprises a positive electrode mixture containing nickel oxyhydroxide, electrolytic manganese dioxide and a graphite conductive agent,
The nickel oxyhydroxide is composed of β-type crystals in which manganese is dissolved,
The alkaline battery whose content rate of the said manganese which occupies for the total amount of nickel and the said manganese contained in the said nickel oxyhydroxide is 0.5-10 mol%. Consisting of positive electrode, negative electrode and alkaline electrolyte,
The positive electrode comprises a positive electrode mixture containing nickel oxyhydroxide, electrolytic manganese dioxide and a graphite conductive agent,
When a molded body made of a mixture of the nickel oxyhydroxide and the graphite conductive agent is immersed in an aqueous solution containing 40 wt% KOH, and a constant current of 5 mA per 1 g of the nickel oxyhydroxide is applied to the molded body The potential of the molded body has a first plateau region of +500 to +100 mV with respect to the Hg / HgO electrode and a second plateau region of +100 to −400 mV with respect to the Hg / HgO electrode,
The discharge capacity per gram of the nickel oxyhydroxide in the first plateau region is 220 to 250 mAh,
An alkaline battery having a discharge capacity per 10 g of the nickel oxyhydroxide in the second plateau region of 10 to 25 mAh.   The content ratio of the nickel oxyhydroxide in the total amount of the nickel oxyhydroxide and the electrolytic manganese dioxide contained in the positive electrode mixture is 10 to 80 wt%, and the electrolytic manganese dioxide occupies the total amount. The alkaline battery according to claim 1, wherein the content is 20 to 90 wt%.   The content of the graphite conductive agent in the total amount of the nickel oxyhydroxide, the electrolytic manganese dioxide, and the graphite conductive agent contained in the positive electrode mixture is 3 to 10 wt%. An alkaline battery according to any one of the above. The positive electrode mixture further contains at least one rare earth metal oxide selected from the group consisting of Y ₂ O ₃ , Er ₂ O ₃ , Tm ₂ O ₃ , Yb ₂ O ₃ and Lu ₂ O ₃ , The content of the rare earth metal oxide in the total of nickel oxyhydroxide, the electrolytic manganese dioxide, the graphite conductive agent, and the rare earth metal oxide is 0.1 to 2 wt%. The alkaline battery described in 1.

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