JP2005071991A - Alkaline battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an alkaline battery having a superior large load discharge characteristic, and improved energy density. <P>SOLUTION: The alkaline battery comprises a positive electrode comprising a positive electrode active material, a negative electrode comprising a negative electrode active material, a separator arranged between the positive electrode and the negative electrode, and an electrolyte. The positive electrode active material contains spherical nickel oxyhydroxide comprising a crystal of a β type structure, and in a powder X-ray diffraction profile targeting Cu of the spherical nickel oxyhydroxide, a half width W of a diffraction peak P by a 001 face is ≤0.6°, a ratio H/W of a height H of the peak P with respect to the half width W is ≥10,000, and an average valence of nickel contained in the spherical nickel oxyhydroxide is ≥2.95. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an alkaline battery containing nickel oxyhydroxide as a positive electrode active material, and more particularly to an alkaline battery such as a nickel battery or a nickel manganese battery.

  Alkaline batteries, especially discharge start-type alkaline batteries and alkaline primary batteries, are arranged in a positive electrode case that also serves as a positive electrode terminal, with a cylindrical positive electrode mixture pellet in close contact with the positive electrode case, and a separator interposed in the center. And an inside-out structure in which a gelled zinc negative electrode is disposed.

  With the spread of digital devices in recent years, the load power of devices using these batteries is gradually increasing. For this reason, a battery excellent in heavy load discharge performance has been desired.

  In order to obtain an alkaline battery excellent in heavy load discharge characteristics, for example, mixing nickel oxyhydroxide with a positive electrode mixture has been proposed (see Patent Document 1). In recent years, such batteries have come into practical use.

The nickel oxyhydroxide used in the alkaline battery can be obtained, for example, by oxidizing spherical or egg-shaped nickel hydroxide with an oxidizing agent such as an aqueous sodium hypochlorite solution. In such an oxidation reaction, β-type nickel hydroxide having a large bulk density (tap density) is used as the spherical nickel hydroxide as a raw material. By oxidizing β-type nickel hydroxide, spherical nickel oxyhydroxide having a β-type main structure is produced. The spherical nickel oxyhydroxide having a β-type having a large tap density and having a main structure thus obtained can be filled in the positive electrode at a high density.
In addition, in alkaline storage batteries, spherical nickel hydroxide whose crystallinity is appropriately controlled is used in order to improve the high-temperature charging characteristics. By using such spherical nickel hydroxide as a raw material, spherical nickel oxyhydroxide having a high oxidation number, that is, high discharge capacity can be obtained.

  Due to the further enhancement of functions of recent digital devices, alkaline batteries are required to have further improved discharge characteristics. In particular, in the alkaline battery containing the above nickel oxyhydroxide, (1) to improve the heavy load discharge characteristics in order to cope with the pulse discharge unique to digital equipment, and (2) to cope with the increase in power consumption of the equipment. In addition, there is a demand for improving the capacity.

  In response to the former request, it has been proposed to use nickel oxyhydroxide coated with cobalt oxide or cobalt oxyhydroxide (see Patent Document 2 and Patent Document 3). By using such nickel oxyhydroxide, not only the heavy load discharge characteristics are improved, but also the capacity is improved.

  In response to the latter demand, studies have been made to improve the nickel oxyhydroxide material itself contained in the positive electrode mixture. For example, it has been proposed to improve the capacity by containing alkali metal ions between crystals of β-type nickel oxyhydroxide (see Patent Document 4).

  In addition, in order to increase the energy density of alkaline batteries containing nickel oxyhydroxide in the positive electrode, the conditions for chemically oxidizing nickel hydroxide are strengthened to increase the oxidation number of nickel contained in nickel oxyhydroxide. Can be considered.

  However, if the conditions for chemical oxidation are increased by simply increasing the concentration and amount of the oxidant used in the oxidation reaction or increasing the ambient temperature, the crystallites having a β-type structure become finer. As a result, the crystallinity of nickel oxyhydroxide is lowered.

In β-nickel oxyhydroxide having low crystallinity, there are many crystallite interfaces which are a kind of defect. In addition, such nickel oxyhydroxide locally contains crystals of γ-type structure which are inactive and do not contribute to the discharge reaction. Therefore, even if the apparent average valence of nickel is high, a sufficient discharge capacity cannot be obtained. Thus, simply increasing the average valence of nickel contained in nickel oxyhydroxide cannot increase the energy density of the alkaline battery.
JP-A-57-72266 JP 2002-338252 A JP 2003-17079 A JP 2001-325594 A

  Therefore, an object of the present invention is to provide an alkaline battery having excellent heavy load discharge characteristics and improved energy density by optimizing the physical properties of nickel oxyhydroxide.

  The present invention relates to a positive electrode made of a positive electrode active material, a negative electrode made of a negative electrode active material, a separator disposed between the positive electrode and the negative electrode, and an alkaline battery made of an electrolytic solution. The positive electrode active material includes spherical nickel oxyhydroxide composed of crystals having a β-type structure. Here, in the powder X-ray diffraction profile targeting Cu of spherical nickel oxyhydroxide, the half-value width W of the diffraction peak P by the (001) plane is 0.6 ° or less. The ratio of the height H of the peak P to the half width W: H / W is 10000 or more. The average valence of nickel contained in the spherical nickel oxyhydroxide is 2.95 or more. The half-value width of the diffraction peak is defined by the difference of 2θ in the peak that takes half the extreme value of the diffraction peak height. The peak height is usually expressed in counts / second (cps).

  In the alkaline battery, the average valence of nickel contained in the spherical nickel oxyhydroxide is preferably 3 or more.

  In the alkaline battery, the spherical nickel oxyhydroxide carries a cobalt oxide, and the average valence of cobalt contained in the cobalt oxide is preferably larger than 3.

  In the alkaline battery, the amount of cobalt oxide supported on the spherical nickel oxyhydroxide is preferably 0.5 to 15 parts by weight per 100 parts by weight of the spherical nickel oxyhydroxide.

  In the alkaline battery, the positive electrode preferably further contains, as an additive, at least one selected from the group consisting of zinc oxide, calcium oxide, yttrium oxide, and titanium oxide.

In the alkaline battery, the positive electrode preferably contains 0.1 to 10 parts by weight of the additive per 100 parts by weight of spherical nickel oxyhydroxide.

  According to the present invention, it is possible to provide an alkaline battery having excellent heavy load discharge characteristics and improved energy density.

An example of the alkaline battery of the present invention will be described with reference to FIG.
The alkaline battery in FIG. 1 includes a positive electrode mixture 2, a gelled negative electrode 3, a separator 4 disposed between the positive electrode mixture 2 and the gelled negative electrode 3, and a power generation element including an electrolyte (not shown), It consists of a positive electrode case 1 containing a power generation element.

  The positive electrode case 1 also serves as a positive electrode terminal and has a bottomed cylindrical shape having a recess at the center of the bottom. A hollow cylindrical positive electrode mixture 2 is disposed inside the positive electrode case 1 so as to be in contact with the positive electrode case 1. A graphite coating film 10 is formed between the positive electrode case 1 and the positive electrode mixture 2.

  A gelled negative electrode 3 is disposed inside the positive electrode mixture 2 with a separator 4 interposed therebetween. The gelled negative electrode 3 and the positive electrode case 1 are insulated by an insulating cap 9.

  A negative electrode current collector 6 is inserted into the gelled negative electrode 3. The negative electrode current collector 6 is integrated with a sealing plate 5 and a bottom plate 7 that also serves as a negative electrode terminal. The opening of the positive electrode case 1 is sealed by caulking the opening end of the positive electrode case 1 to the peripheral edge of the bottom plate 7 via the sealing plate 5. The outer surface of the positive electrode case 1 is covered with an exterior label 8.

  The electrolytic solution is used to wet the positive electrode mixture 2 and the separator 4. As this electrolytic solution, those known in the art can be used. An example is an aqueous solution containing 40% by weight of potassium hydroxide.

  As the gelled negative electrode 3, those known in the art can be used. For example, examples of such a gelled negative electrode include those made of polyacrylic acid soda as a gelling agent, an alkaline electrolyte, and zinc powder as a negative electrode active material. In addition, the alkaline electrolyte used for the gelled negative electrode may be the same as or different from the above electrolyte.

  In the present embodiment, the positive electrode mixture 2 is composed of nickel oxyhydroxide and manganese dioxide.

Next, nickel oxyhydroxide, which is a positive electrode active material, will be described.
In the present invention, the spherical nickel oxyhydroxide used as the positive electrode active material consists of crystals having a β-type structure. In the powder X-ray diffraction profile of the spherical nickel oxyhydroxide, the half width of the diffraction peak due to the (001) plane is 0.6 ° or less, and the peak height of the diffraction peak due to the (001) plane with respect to the half width is The ratio ((peak height) / (half width)) is 10,000 or more.

  Spherical nickel oxyhydroxide with high crystallinity such that the half-value width is 0.6 ° or less and (peak height) / (half-value width) is 10,000 or more facilitates the reduction reaction of the nickel species during discharge. Proceed to. That is, by having the above characteristic values, the utilization rate of nickel oxyhydroxide as the positive electrode active material is improved. Furthermore, it is possible to improve the heavy load discharge characteristics of a battery containing such nickel oxyhydroxide.

  On the other hand, when the half width is larger than 0.6 °, many defects are included in the nickel oxyhydroxide, and a locally inactive structure (γ-type structure) exists. In such a case, it is difficult to obtain a sufficient discharge capacity.

  Also, when (peak height) / (half width) is smaller than 10,000, it is difficult to obtain a sufficient discharge capacity as in the case where the half width is larger than 0.6 °.

  Furthermore, the average oxidation number (hereinafter also referred to as average valence) of nickel contained in the spherical nickel oxyhydroxide is 2.95 or more. The average valence is preferably 3 or more and 3.05 or less.

  When nickel contained in nickel oxyhydroxide has an average valence of 2.95 or more, a battery having a sufficiently high capacity enough to meet the valence can be obtained. On the other hand, if the average valence is less than 2.95, the capacity becomes insufficient.

  As described above, in the spherical nickel oxyhydroxide used in the present invention, the average valence of nickel is high, and the nickel reduction reaction is performed smoothly. By using such spherical nickel oxyhydroxide, the energy density of the alkaline battery can be improved, and the heavy load discharge characteristics can be improved.

The average particle diameter of the spherical nickel oxyhydroxide is preferably in the range of 8 to 20 μm, and the tap density (500 times) is preferably in the range of 2.2 to 2.4 g / cm ³ . When the average particle diameter and the tap density are in such ranges, the packing density of the spherical nickel oxyhydroxide can be increased.

  The spherical nickel oxyhydroxide may carry a cobalt oxide having an average cobalt valence greater than 3.0. Moreover, it is preferable that the average valence of cobalt is 3.1 or more and 3.6 or less.

A cobalt oxide having an average valence of cobalt greater than 3 has very high electronic conductivity. For this reason, when the spherical nickel oxyhydroxide carries the cobalt oxide, the current collecting property of the spherical nickel oxyhydroxide can be improved. By using such nickel oxyhydroxide carrying a cobalt oxide as the positive electrode active material, it is possible to obtain a battery having a higher capacity (high utilization factor) and excellent heavy load discharge characteristics. Further, cobalt oxide having a valence of 3.1 or higher has high chemical stability during battery storage. For this reason, it becomes possible to obtain a battery having high reliability even after storage at a high temperature.
On the other hand, a cobalt oxide having an average valence of cobalt exceeding 3.6 is difficult to produce.

  Further, the amount of cobalt oxide supported on the spherical nickel oxyhydroxide is preferably 0.5 to 15 parts by weight and preferably 1 to 5 parts by weight per 100 parts by weight of the spherical nickel oxyhydroxide. Further preferred. By making the loading amount within the above range, the effect of the spherical nickel oxyhydroxide supporting the cobalt oxide can be sufficiently exhibited. That is, it is possible to sufficiently improve the utilization rate of spherical nickel oxyhydroxide and reduce the discharge polarization during heavy load discharge. Furthermore, if the supported amount is in the above range, even if the volume of nickel oxyhydroxide is increased by supporting cobalt oxide, the utilization rate of nickel oxyhydroxide is increased more than the increase in volume. For this reason, the volume energy density of nickel oxyhydroxide can be enlarged. Therefore, by using such nickel oxyhydroxide, it is possible to make the alkaline battery particularly excellent in high capacity and heavy load discharge characteristics.

  Moreover, it is preferable that the positive electrode of the said alkaline battery contains at least 1 sort (s) selected from the group which consists of zinc oxide, calcium oxide, yttrium oxide, and titanium oxide as an additive. These additives can increase the oxygen generation overvoltage of nickel oxyhydroxide. For this reason, the self-decomposition reaction of nickel oxyhydroxide can be suppressed. Therefore, when the positive electrode contains the additive as described above, it is possible to suppress a decrease in capacity and a leakage phenomenon when the battery is stored for a long time at a high temperature. That is, by adding such an additive to the positive electrode, the reliability of the alkaline battery can be significantly improved.

  The addition amount of the additive is preferably 0.1 to 10 parts by weight, more preferably 0.5 to 3 parts by weight, per 100 parts by weight of spherical nickel oxyhydroxide. When the additive amount is in the above range, it is possible to sufficiently suppress the self-decomposition reaction of the spherical nickel oxyhydroxide while minimizing the decrease in the filling amount of the positive electrode active material. That is, it becomes possible to suppress the self-decomposition reaction of nickel oxyhydroxide without reducing the battery capacity.

  Considering the balance of battery characteristics and price, the contents of nickel oxyhydroxide and manganese dioxide in the total amount of nickel oxyhydroxide and manganese dioxide contained in the positive electrode mixture are 10 to 80% by weight and 20 to 20%, respectively. It is preferably 90% by weight. Further, from the viewpoint of obtaining a battery having an excellent balance of characteristics, the contents of nickel oxyhydroxide and manganese dioxide are preferably 30 to 60% by weight and 40 to 70% by weight, respectively. This is due to the following reason. When comparing manganese dioxide and nickel oxyhydroxide, 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.

  The average valence of nickel contained in the nickel oxyhydroxide particles can be determined, for example, by the following weight method (dimethylglyoxime method) and oxidation-reduction titration of nickel oxyhydroxide particles.

This will be specifically described below.
(1) Measurement of metal weight ratio by weight method (dimethylglyoxime method) etc. Nickel oxyhydroxide particles are added to a nitric acid aqueous solution and heated to dissolve the nickel oxyhydroxide particles.

A tartaric acid aqueous solution and ion-exchanged water are added to the resulting solution to adjust its volume, and then aqueous ammonia and acetic acid are added to this solution to keep the pH of the solution weakly acidic (pH = 4-6). .
At this time, the solution may contain ions that may cause measurement errors. For example, when ions that can cause measurement errors are cobalt ions, potassium bromate is added to oxidize the cobalt ions to a trivalent state. Thereby, formation of a complex of cobalt ions and dimethylglyoxime can be prevented.

  Next, while heating and stirring this solution, an ethanol solution of dimethylglyoxime is added to precipitate nickel ions as a dimethylglyoxime complex compound.

  Subsequently, suction filtration is performed, and the generated precipitate is collected. The collected precipitate is dried in an atmosphere of 110 ° C., and then the weight of the precipitate is measured.

The nickel weight ratio contained in the predetermined amount of nickel oxyhydroxide particles is calculated by the following equation.
Nickel weight ratio = [weight of precipitate (g) × 0.2032] / [weight of nickel oxyhydroxide particles (g)]

In addition, content of additional metals, such as cobalt and zinc with little content, is calculated | required as follows.
First, nickel oxyhydroxide particles are dissolved in a nitric acid solution. By using the obtained solution for ICP emission analysis, the content of the additive metal can be obtained with high accuracy.

(2) Measurement of average nickel valence by oxidation-reduction titration Potassium iodide and sulfuric acid are added to nickel oxyhydroxide particles, and stirring is sufficiently continued to completely dissolve the nickel oxyhydroxide particles. In this process, nickel ions having a higher valence than divalent oxidize potassium iodide to iodine and are reduced to divalent.

  Subsequently, the produced iodine is titrated with a 0.1 mol / L sodium thiosulfate aqueous solution. The titration at this time reflects the amount of electrons received from iodide ions before the nickel ions and cobalt ions are reduced to divalent. That is, this titration reflects the amount of nickel and cobalt whose valence is greater than two.

  Therefore, by using the value of the metal weight ratio obtained in (1) above and assuming that the cobalt in the nickel oxyhydroxide is 3.5 valent, the average valence of nickel contained in the nickel oxyhydroxide is Desired.

  Hereinafter, the present invention will be described in detail based on examples.

(Preparation of nickel oxyhydroxide solid solution)
An aqueous ammonia solution of nickel sulfate (an aqueous solution in which Ni ²⁺ is present as an ammine complex), an aqueous ammonia solution of cobalt sulfate, an aqueous ammonia solution of zinc sulfate, and an aqueous sodium hydroxide solution were supplied by a pump to a reaction vessel equipped with a stirring blade. At this time, the supply amount of each solution was adjusted so that the reaction solution in the reaction tank had a predetermined pH.

  The reaction solution in the reaction vessel was sufficiently stirred with a stirring blade to precipitate spherical nickel hydroxide (β-type) particles. Furthermore, nickel hydroxide particles were grown by continuing stirring. The obtained spherical nickel hydroxide had cobalt and zinc dissolved in the crystal.

  Next, the obtained particles were placed in a sodium hydroxide aqueous solution housed in another reaction vessel, and heated therein to remove sulfate radicals. Thereafter, the particles were washed with water and dried to obtain spherical nickel hydroxide solid solution particles. Here, the amount of cobalt contained in the solid solution particles (in terms of metal) was 1% by weight of the entire solid solution particles. Further, the amount of zinc (in metal conversion) was set to 3% by weight of the entire solid solution particles.

The average particle size of the obtained spherical nickel hydroxide solid solution particles was measured using a laser diffraction particle size distribution meter. As a result, the volume-based average particle diameter of the solid solution particles was 9 μm. The BET specific surface area of the solid solution particles was 5.0 m ² / g.

The crystal structure of the nickel hydroxide solid solution particles thus produced was measured by a powder X-ray diffraction method. Here, the measurement conditions were as follows.
[Measurement equipment] Rigaku Co., Ltd., powder X-ray diffractometer "RINT1400"
[Anti-cathode] Cu
[Filter] Ni
[Tube voltage] 40 kV
[Tube current] 100mA
[Sampling angle] 0.02 °
[Scanning speed] 3.0 ° / min [Diverging slit] 1/2 °
[Scattering slit] 1/2 °

  The diffraction peak by the (001) plane of the obtained nickel hydroxide solid solution particles was observed around 2θ = 19 °. The half width of this diffraction peak was 0.55 °, and the peak height was 5800 cps under the above measurement conditions. The ratio of the peak height to the full width at half maximum ([peak height] / [full width at half maximum]), which is a measure of crystallinity, was 10540. From these values, it was found that a nickel hydroxide solid solution having relatively high crystallinity was obtained.

  Subsequently, the obtained spherical nickel hydroxide solid solution particles were subjected to a chemical oxidation treatment to obtain spherical nickel oxyhydroxide.

  First, the nickel hydroxide solid solution particles were put into a 0.5 mol / L sodium hydroxide aqueous solution. Next, an aqueous solution containing sodium hypochlorite as an oxidizing agent (effective chlorine concentration: 5% by weight) was added. The mixture was stirred to convert the nickel hydroxide solid solution particles into nickel oxyhydroxide solid solution particles. At this time, the addition amount x of the oxidizing agent, the reaction atmosphere temperature y, and the oxidation treatment time (stirring time) z were changed as shown in Table 1.

In addition, the addition amount of an oxidizing agent is represented by the equivalent unit by making into 1 equivalent the quantity which can increase the oxidation number of all the nickel contained in nickel hydroxide one theoretically.
Further, the oxidation treatment time (stirring time) is represented by setting the shortest treatment time (4 hours) as 1, and the actual treatment time as a multiple thereof.

  The obtained particles were sufficiently washed with water and then vacuum dried at 60 ° C. to obtain spherical nickel oxyhydroxide solid solution particles 1 to 27. These spherical nickel oxyhydroxides had an average particle size of about 10 μm.

  Next, in order to confirm the crystal structure of the obtained spherical nickel oxyhydroxide solid solution particles 1 to 27, powder X-ray diffraction measurement was performed under the same conditions as those for the nickel hydroxide solid solution particles.

As an example, the diffraction profile of the nickel oxyhydroxide solid solution particle 2 is shown in FIG.
Similar to β-type nickel hydroxide, a strong peak derived from the (001) plane (crystal plane perpendicular to the c-axis) was observed near 2θ = 19 °.

  Further, in the X-ray diffraction profile of β-type nickel hydroxide, the diffraction peak due to the crystal planes ((100) plane and (101) plane) related to the ion periodic arrangement in the a-axis direction is 2θ = 30 to 40 °. It is known to appear in However, this peak becomes broad with the oxidation of nickel hydroxide. In the diffraction profile of FIG. 2, this peak could not be clearly grasped.

  Therefore, the obtained nickel oxyhydroxide basically has a crystal structure of β-type nickel oxyhydroxide having no interlayer elongation.

  Next, FIG. 3 shows an enlarged view of the low angle region of the diffraction profile (A) of the nickel oxyhydroxide solid solution particle 2 and the diffraction profile (B) of the nickel oxyhydroxide solid solution particle 26.

  The half width of the diffraction peak on the (001) plane of nickel oxyhydroxide and its peak height were changed by the difference in the oxidation conditions. In the solid solution particle 26, compared to the solid solution particle 2, the peak half-value width of the diffraction peak due to the (001) plane increased, and the peak intensity decreased. From this result, it was found that the crystallinity of the solid solution particles 26 was lower than that of the solid solution particles 2.

  Further, in the solid solution particles 26 with lowered crystallinity, a diffraction peak that appears to be derived from inert γ-type nickel oxyhydroxide appears around 2θ = 10 °, and the peak intensity tends to increase. The inactive γ-type nickel oxyhydroxide refers to a material in which the layer interval is greatly extended more than the layer interval in the case of a normal γ-type structure.

  Approximate half-value width of diffraction peak by (001) plane, peak height of diffraction peak by (001) plane, and crystallinity obtained by powder X-ray diffraction measurement of nickel oxyhydroxide solid solution particles 1-27. Table 2 shows the ratio of the peak height to the full width at half maximum ([peak height] / [half width]).

Moreover, the average valence of nickel contained in the nickel oxyhydroxide solid solution particles 1 to 27 was determined as described above.
The results thus obtained are also shown in Table 2.

  When the addition amount x of the oxidizing agent and the reaction atmosphere temperature y were the same, the average valence of nickel increased as the oxidation treatment time z increased. Further, as the oxidation treatment time z increased, the half width of the diffraction peak due to the (001) plane decreased and the peak height increased. That is, it was found that the crystallinity is improved.

  In the chemical oxidation of nickel hydroxide by an oxidizing agent, the process of extracting protons and electrons from the initial nickel hydroxide involves destruction or refinement of the crystallites of nickel hydroxide. When the chemical oxidation of nickel progresses and the average valence of nickel is near trivalent, the nickel is rearranged in the c-axis direction of the crystal of nickel oxyhydroxide and the crystallinity of nickel oxyhydroxide is improved. It suggests.

  On the other hand, when the addition amount x of the oxidizing agent is as large as 1.2 to 1.4 equivalent and the reaction atmosphere temperature y is as high as 50 to 60 ° C., the crystallinity of the resulting nickel oxyhydroxide tends to decrease as a whole. there were. This is presumed that in the initial stage of the oxidation reaction, the extraction reaction of protons or electrons from nickel hydroxide occurred very vigorously, resulting in excessive refinement of crystallites. In addition, in the nickel oxyhydroxide solid solution particles having such lowered crystallinity, the generation ratio of the inactive γ species tended to increase.

Next, an alkaline battery containing such nickel oxyhydroxide 1-27 as the positive electrode active material was produced as follows.
(Preparation of positive electrode)
The obtained nickel oxyhydroxide solid solution particles, manganese dioxide, and graphite were blended at a weight ratio of 50: 50: 5. Further, 5 parts by weight of zinc oxide was added per 100 parts by weight of nickel oxyhydroxide solid solution particles. Next, 1 part by weight of the electrolytic solution per 100 parts by weight of the positive electrode active material (total of nickel oxyhydroxide solid solution particles and manganese dioxide) was added to obtain a mixture. This mixture was stirred with a mixer to obtain a granular material having a predetermined particle size. The obtained granular material was pressure-molded into a hollow cylindrical shape to obtain positive electrode mixtures 1-27.

(Preparation of negative electrode)
A gelled negative electrode was prepared by mixing sodium acrylate as a gelling agent, an alkaline electrolyte, and zinc powder as a negative electrode active material in a weight ratio of 2.5: 100: 200. As the alkaline electrolyte, a 40% by weight potassium hydroxide aqueous solution was used.

(Preparation of alkaline battery)
Using the positive electrode mixture and the gelled negative electrode obtained as described above, an AA size alkaline battery as shown in FIG. 1 was produced.

  As the positive electrode case, a case made of a nickel-plated steel plate was used. A graphite coating film was formed inside the positive electrode case.

  A plurality of the positive electrode mixtures were inserted into the positive electrode case, and then the positive electrode mixture was pressed again to adhere to the inner surface of the positive electrode case.

  Next, a separator and an insulating cap were inserted inside the positive electrode mixture. Thereafter, an electrolyte solution (40 wt% potassium hydroxide aqueous solution) was injected into the battery case to wet the separator and the positive electrode mixture.

  After injecting the electrolytic solution, the gelled negative electrode was filled inside the separator. Thereafter, a negative electrode current collector in which the sealing body and the bottom plate were integrated was inserted into the gelled negative electrode. The opening end of the positive electrode case was caulked to the bottom plate via a sealing plate to seal the opening of the positive electrode case. Finally, the outer surface of the positive electrode case was covered with an exterior label to complete the battery.

  The obtained batteries were designated as batteries 1 to 21, respectively. The batteries 2, 3, 11, 12, and 21 are the batteries of this example. The batteries other than the above are comparative batteries.

(Evaluation)
The produced alkaline batteries were each continuously discharged at 20 ° C. with a constant power of 1 W. At this time, the discharge time until the battery voltage reached a final voltage of 0.9 V was measured. The results obtained are shown in Table 3. In Table 3, the discharge time of the battery 2 is defined as 100, and the discharge time of other batteries is normalized.

  From Table 3, it can be seen that batteries 2, 3, 11, 12, and 21 maintain a longer discharge time than the comparative battery. The nickel oxyhydroxide contained in these batteries has a relatively high crystallinity compared to the nickel oxyhydroxide contained in the comparative battery. In such highly crystalline nickel oxyhydroxide, the nickel reduction reaction during discharge proceeds smoothly. For this reason, it is considered that the electric capacity is increased to the maximum even in heavy load discharge.

  Among the batteries 2, 3, 11, 12, and 21, the batteries 3, 12 and 21 containing nickel oxyhydroxide having an average valence of nickel of 3 or more have a longer discharge time than other batteries. It has become. For this reason, it is preferable that the average valence of nickel contained in the nickel oxyhydroxide solid solution particles is 3 or more.

  In the above examples, spherical nickel oxyhydroxide solid solution particles in which cobalt and zinc were dissolved in the crystal were used. In addition, the half-width of the diffraction peak due to the (001) plane, the peak height of the diffraction peak due to the (001) plane relative to the half-width, and the spherical nickel oxyhydroxide having an average valence of nickel within the above range If it is, the same effect can be acquired.

  Further, the method for producing such a highly crystalline spherical nickel oxyhydroxide is not limited to the method shown in this example.

  Such spherical nickel oxyhydroxide carries a cobalt oxide containing cobalt having an average valence greater than 3.0 (for example, a highly conductive cobalt oxide such as γ-cobalt oxyhydroxide). May be. Thereby, it is possible to further enhance the current collecting property of electrons from the nickel oxyhydroxide to further increase the energy density.

  When preparing the positive electrode mixture, the blending ratio of the spherical nickel oxyhydroxide solid solution particles, manganese dioxide, and graphite is 50: 50: 5, but is not limited to this ratio.

  Furthermore, in the said Example, 5 weight part zinc oxide was added to the positive electrode mixture from 100 viewpoints of spherical nickel oxyhydroxide from a viewpoint of storage characteristic improvement. Instead of zinc oxide such as zinc oxide, any of calcium oxide, yttrium oxide, or titanium oxide may be used. Moreover, it is preferable that the addition amount exists in the range of 0.1-10 weight part per 100 weight part of spherical nickel oxyhydroxide.

  According to the present invention, it is possible to provide an alkaline battery which is excellent in heavy load discharge characteristics and has a high energy density.

It is the front view which notched some alkaline batteries concerning one embodiment of the present invention. It is a powder X-ray-diffraction profile of the nickel oxyhydroxide solid solution particle 2 used in the Example of this invention. 2 is an enlarged view of a low angle region of a powder X-ray profile (A) of nickel oxyhydroxide solid solution particles 2 and a powder X-ray diffraction profile (B) of solid solution particles 26. FIG.

Explanation of symbols

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

Claims (6)

A positive electrode made of a positive electrode active material,
A negative electrode made of a negative electrode active material,
A separator disposed between the positive electrode and the negative electrode, and an alkaline battery comprising an electrolyte,
The positive electrode active material includes spherical nickel oxyhydroxide composed of crystals having a β-type structure,
In the powder X-ray diffraction profile targeting Cu of the spherical nickel oxyhydroxide, the half width W of the diffraction peak P by the (001) plane is 0.6 ° or less,
Ratio of the height H of the peak P to the half width W: H / W is 10000 or more,
An alkaline battery in which an average valence of nickel contained in the spherical nickel oxyhydroxide is 2.95 or more.   The alkaline battery according to claim 1, wherein an average valence of nickel contained in the spherical nickel oxyhydroxide is 3 or more.   The alkaline battery according to claim 1, wherein the spherical nickel oxyhydroxide carries a cobalt oxide, and the average valence of cobalt contained in the cobalt oxide is larger than 3. 3.   The alkaline battery according to claim 3, wherein the amount of the cobalt oxide supported on the spherical nickel oxyhydroxide is 0.5 to 15 parts by weight per 100 parts by weight of the spherical nickel oxyhydroxide.   The alkaline battery according to claim 1, wherein the positive electrode further contains, as an additive, at least one selected from the group consisting of zinc oxide, calcium oxide, yttrium oxide, and titanium oxide. The alkaline battery according to claim 5, wherein the positive electrode contains 0.1 to 10 parts by weight of the additive per 100 parts by weight of the spherical nickel oxyhydroxide.

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