JP2002117858A - Alkaline storage battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an alkaline storage battery having high charging efficiency in high temperature and excellent cycle characteristics. SOLUTION: The alkaline storage battery has a non-sintering type positive electrode which makes nickel hydroxide of which the particle surfaces are covered by cobalt hydroxide particles of plate shape having thickness in the range of 0.025 to 0.3 μm, as an active material, has a negative electrode, which makes the hydrogen storage alloy as the active material, separator, and electrolytic liquid. The above non-sintering type positive electrode or the negative electrode is made to contain a magnesium compound. It is desirable that a content amount of the magnesium compound in the above positive electrode is 0.003 to 0.6% by the weight of magnesium to the weight of nickel hydroxide. Moreover, it is desirable that a content amount of the magnesium compound in the negative electrode is 0.003 to 0.6% by the weight of magnesium to the weight of the hydrogen storage alloy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alkaline storage battery using a positive electrode containing specific nickel hydroxide as an active material.

[0002]

2. Description of the Related Art As a positive electrode for an alkaline storage battery, a sintered nickel electrode in which nickel powder is impregnated into pores of a sintered substrate and filled with an active material, and a nickel hydroxide as an active material are used as a binder. And a non-sintered nickel electrode in which a paste is formed by dispersing in water or a solvent together with a thickener and the like, and the paste is filled in a conductive porous substrate serving as a current collector.

[0003] The former sintered nickel electrode has an excellent utilization rate of the active material because of the high conductivity of the sintered substrate, but it is difficult to increase the porosity of the sintered substrate. It is not possible to increase the filling amount of nickel, it is difficult to achieve a high capacity, and since the bonding force between nickel particles is weak, the active material tends to fall off when using a sintered substrate with high porosity. There was a problem.

Therefore, the latter non-sintered nickel electrode has been proposed as a positive electrode for a hydride secondary battery. In this non-sintered nickel electrode, the packing density of nickel hydroxide as an active material is increased. Although it has the advantage of being easy and easy to manufacture electrodes, since the distance between the active material nickel hydroxide and the base material is long,
There is a problem that the conductivity is reduced and the utilization rate of the active material is reduced.

[0005] Therefore, in the non-sintered nickel electrode, metal cobalt or a cobalt compound such as cobalt monoxide or cobalt hydroxide is added to the electrode in order to increase the utilization rate of the active material and achieve a high capacity. It has been proposed to add as These cobalt-based conductive additives are oxidized during charging in an alkaline electrolyte to form higher-order cobalt oxides such as cobalt oxyhydroxide, forming a conductive network that electrically connects the nickel hydroxide particles. It is known to

However, since the cobalt-based conductive additive is difficult to be uniformly dispersed in the electrode and tends to be unevenly distributed, the network of the cobalt oxide formed therefrom tends to be non-uniform, and it is difficult to secure good conductivity. Further, in order to form a network over the entire electrode, if the amount of the cobalt-based conductive additive is increased, the amount of nickel hydroxide to be filled will decrease. Therefore, recently, in order to form a uniform network without lowering the filling amount of nickel hydroxide, the surface is preliminarily treated with water instead of or together with the above-mentioned cobalt-based conductive auxiliary. It has been proposed to use nickel hydroxide particles coated with cobalt oxide, etc.
-23467, JP-A-62-234868, JP-A-4-4698, and the like.

[0007]

SUMMARY OF THE INVENTION In order to improve the utilization rate of the positive electrode, the present inventors studied nickel hydroxide particles having cobalt hydroxide particles deposited on the particle surface and studied the shape of the cobalt hydroxide particles. And the thickness is set to 0.
When nickel hydroxide, which is in the range of 025 to 0.3 μm and whose particle surface is coated with plate-like cobalt hydroxide particles whose crystal growth has progressed to some extent, is used as the active material, the utilization rate of the positive electrode is greatly improved. I found that I can do it. Particularly, the thickness of the cobalt hydroxide particles is 0.03 to 0.1.
It was also found that when the particle size was μm, the coverage of the nickel hydroxide on the particle surface was improved, and a higher utilization rate was obtained.

[0008] However, the nickel hydroxide also has a problem in that when it is exposed to a high-temperature atmosphere, the charging efficiency is reduced and the utilization rate is reduced. That is, since the charging potential of nickel hydroxide is close to the oxygen generation potential, a competitive reaction between oxygen generation and the charging reaction occurs at the end of charging, and the charging of nickel hydroxide is hindered. The charging efficiency in a high-temperature atmosphere is reduced, and the utilization rate is reduced. In order to improve the charging efficiency, lithium hydroxide or sodium hydroxide is added to the electrolytic solution, calcium hydroxide, calcium oxide, zinc oxide, cadmium hydroxide is added to the positive electrode, or Sr, S
c, Al, Ga, Tu, Zr, Nb, Bi, Mo, A
It has been proposed to dissolve g, Sn, Sb, V, Cr, Mn, Fe, Cu, etc. in solid solution (JP-A-10-4094).
No. 8, JP-A-10-149821). However, the addition of generally used calcium hydroxide or calcium oxide to the positive electrode has a problem in that it tends to form lumps (lumps) during the preparation of the paste, and a uniform paste cannot be obtained. The solid solution of the dissimilar metal into the metal greatly changes the physical properties, and has problems in production such as a decrease in the utilization factor and difficulty in obtaining a uniform solid solution.

At the present time, satisfactory results cannot be obtained with regard to cycle characteristics, and further improvement is demanded. This cycle characteristic is such that the electrolyte dies due to the swelling of the positive electrode and the deterioration of the negative electrode, the internal resistance increases, and its life is exhausted.However, in an alkaline storage battery using nickel hydroxide as a positive electrode active material, In addition, since the charging potential of nickel hydroxide is close to the potential for generating oxygen, a competitive reaction occurs between the generation of oxygen and the charging reaction at the end of charging, thereby preventing the charging of nickel hydroxide and increasing the number of cycles. And this phenomenon becomes remarkable. Therefore, it is necessary to improve the charging efficiency in order to improve the cycle characteristics.

The present invention solves the problems of the prior art when the above-mentioned non-sintered nickel electrode is used as a positive electrode, and provides an alkaline storage battery having high charge efficiency and excellent cycle characteristics. Aim.

[0011]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the above-mentioned problems, and as a result, have a thickness of 0.02.
Non-sintered positive electrode using nickel hydroxide whose particle surface is coated with plate-like cobalt hydroxide particles in the range of 5 to 0.3 μm as active material, negative electrode using hydrogen storage alloy as active material, separator and electrolysis In an alkaline battery having a liquid, it has been found that by including a magnesium compound in the non-sintered positive electrode or the negative electrode, an alkaline storage battery having high charge efficiency and excellent cycle characteristics can be provided.

That is, the alkaline storage battery of the present invention comprises a non-sintered nickel hydroxide having an active material of nickel hydroxide coated with plate-like cobalt hydroxide particles having a thickness in the range of 0.025 to 0.3 μm. It has a positive electrode, a negative electrode using a hydrogen storage alloy as an active material, a separator, and an electrolytic solution. The non-sintered positive electrode or the negative electrode contains a magnesium compound.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, examples of the magnesium compound contained in the non-sintered positive electrode or negative electrode include magnesium oxide and magnesium hydroxide. When the magnesium compound is contained in the non-sintered positive electrode, when the cobalt hydroxide coating the surface of the nickel hydroxide particles forms a conductive network, the magnesium compound dissolves in the electrolytic solution and the magnesium hydroxide And precipitate on the surface of the nickel hydroxide particles.

As described above, magnesium hydroxide precipitates on the surface of the nickel hydroxide particles, so that the surface of the nickel hydroxide particles is covered with the magnesium hydroxide, thereby improving the efficiency of the battery when charged at a high temperature. improves. That is, since magnesium hydroxide coats the surface of the nickel hydroxide particles, the oxygen generation overvoltage increases, delaying the generation of oxygen at the end of charging, and the nickel hydroxide is easily charged. Further, since the magnesium hydroxide covers the surface of the nickel hydroxide particles, swelling of the nickel hydroxide accompanying the charge / discharge cycle is also suppressed. In addition, since magnesium hydroxide is hydrophilic, nickel hydroxide coated with magnesium hydroxide has better electrolyte circulation, and the electrode reaction is smooth even at low temperature charge / discharge and high rate discharge. It does not progress and the utilization rate does not decrease. The dissolution and precipitation of the magnesium compound as described above to coat the surface of the nickel hydroxide particles as magnesium hydroxide may be performed in the battery, or may be performed in advance in an electrode state before assembling into the battery. Is also good. When the magnesium compound is contained in the non-sintered positive electrode, it is preferable that the magnesium compound be contained in the positive electrode mixture-containing paste during the production process of the non-sintered positive electrode.

In order to improve the charging efficiency and to keep the stability of the positive electrode mixture-containing paste within a range not lowering the content of the magnesium compound, the weight of magnesium in the magnesium compound is set to the weight of nickel hydroxide. 0.003 to 0.6% (nickel hydroxide 1
(The ratio of magnesium in the magnesium compound to 0.003 parts by weight with respect to 00 parts by weight) is preferably within a range, more preferably 0.006 to 0.5%.

Also, it has been found that when a magnesium compound is contained in the negative electrode, the efficiency when the battery is charged at a high temperature can be improved as in the case where the magnesium compound is contained in the positive electrode. When the magnesium compound is contained in the negative electrode, the magnesium compound dissolves in the electrolytic solution in the battery, precipitates as magnesium hydroxide on the positive electrode surface, and coats the surface of the positive electrode or the positive electrode active material, and has the same effect as described above. Is expressed. That is, the magnesium hydroxide dissolved and precipitated from the magnesium compound coats the surface of the nickel hydroxide particles, thereby increasing the oxygen generation overvoltage, delaying the oxygen generation at the end of charging, and making the nickel hydroxide easily charged. Also in the case where the negative electrode contains a magnesium compound, it is preferable that the magnesium compound be contained in the negative electrode mixture-containing paste during the production process of the negative electrode. in this way,
When the magnesium compound is contained in the negative electrode, similarly to the case where the magnesium compound is contained in the positive electrode, the charging efficiency when the battery is charged at a high temperature can be improved, so that the magnesium compound is one of the positive electrode and the negative electrode. Not only in the case where it is contained only in the positive electrode but also in the case where the positive electrode and the negative electrode are contained.

When the magnesium compound is contained in the negative electrode as described above, the content of the magnesium compound in the magnesium compound should be within the range not only to improve the charging efficiency but also not to decrease the stability of the negative electrode mixture-containing paste. The weight of magnesium is 0.003 to 0.6% based on the weight of the hydrogen storage alloy of the negative electrode (0.003% by weight of magnesium in the magnesium compound relative to 100 parts by weight of the hydrogen storage alloy).
０．６0.6 parts by weight).
More preferably, the content is 0.006 to 0.3%.

The present inventors have further studied the above alkaline storage battery. As a result, an alkaline storage battery using a non-sintered positive electrode containing a magnesium compound mainly contains potassium hydroxide as an electrolytic solution, It has been found that when an alkaline aqueous solution containing a sodium compound and a zinc compound such as zinc oxide is used, the charging efficiency can be further improved.

The content of the sodium hydroxide is as follows:
From the viewpoint of appropriate expression of an appropriate effect and suppression of the influence on other characteristics, the content is preferably 1 to 10% by weight, more preferably 2 to 6% by weight in the electrolytic solution. Also,
When zinc oxide is used, the content of the oxide compound in the electrolytic solution is preferably 1 to 6% by weight, more preferably 2.5 to 5.5% by weight, for the same reason as described above.

In the present invention, the positive electrode has a thickness of 0.025.
Nickel hydroxide, the surface of which is coated with plate-like cobalt hydroxide particles in the range of ~ 0.3 μm, is used as the positive electrode active material. For example, the positive electrode active material may include, as necessary, a conductive additive or a binder. Is added and mixed in the presence of water or a solvent to prepare a paste containing the positive electrode mixture (in this case, the binder is formed into a solution or dispersion previously dissolved or dispersed in water or a solvent, and then mixed with the positive electrode active material, etc.). The positive electrode mixture-containing paste thus obtained may be applied to a porous base material also serving as a current collector, filled and dried to form a positive electrode mixture layer. It is produced by pressing. However, the method for producing the positive electrode is not limited to the method described above, but may be another method. When the non-sintered positive electrode contains a magnesium compound, it is preferable that the magnesium compound be contained in the positive electrode mixture-containing paste. In producing the positive electrode, it is preferable to use, for example, a divalent cobalt compound such as cobalt oxide or cobalt hydroxide as the conductive additive. This cobalt compound is 0.5 to 6 in weight of cobalt with respect to the weight of nickel hydroxide as an active material.
% (A proportion of 0.5 to 6 parts by weight of cobalt in the cobalt compound with respect to 100 parts by weight of nickel hydroxide). By setting the use amount of the cobalt compound in this range, the conductivity can be further increased without sacrificing the filling amount of the active material, and a high-capacity non-sintered positive electrode can be obtained.

Examples of the binder include carboxymethyl cellulose, polytetrafluoroethylene, styrene-butadiene copolymer, poly-N-vinylacetamide,
A styrene-2-ethylhexyl acrylate copolymer and the like can be mentioned, and examples of the porous substrate include a metal foam, a punching metal, an expanded metal and the like.

In the present invention, the positive electrode is preferably immersed in an aqueous alkaline solution before assembling the battery to slightly oxidize the added cobalt compound and the cobalt hydroxide particles covering the surface of the nickel hydroxide particles. . As conditions for the alkali immersion treatment, the temperature is preferably 35 to 100 ° C, more preferably 50 to 90 ° C, and the immersion time is preferably 0.2 to 2.5 hours, more preferably 0.25 to 2 hours. By performing the immersion treatment in the alkaline aqueous solution, when charging is performed before assembling the battery, the formation of a higher-order conductive cobalt oxide is facilitated, and the utilization factor and high-temperature storage characteristics can be improved. .

In the present invention, the nickel hydroxide coated on the particle surface with plate-like cobalt hydroxide particles having a thickness in the range of 0.025 to 0.3 μm used as the positive electrode active material is coated with the cobalt hydroxide. In order to improve the conductivity and not to affect the amount of the active material charged when used for the positive electrode, the amount of cobalt in cobalt hydroxide relative to nickel hydroxide is 2 to 6%.
(The ratio of the amount of cobalt in cobalt hydroxide to 2 to 6 parts by weight with respect to 100 parts by weight of nickel hydroxide), and more preferably 3 to 5%. In addition, the coating amount of cobalt hydroxide with respect to nickel hydroxide can be determined by measurement by atomic absorption analysis.

In the nickel hydroxide coated on the surface with the cobalt hydroxide particles, it is preferable that the base nickel hydroxide is a solid solution of cobalt and zinc. This is because the precipitation form of cobalt hydroxide is affected by the composition, crystallinity, and pore structure of nickel hydroxide, but when using nickel hydroxide particles in which cobalt and zinc are dissolved, the particle surface This is because the dispersion of the thickness of the cobalt hydroxide particles to be coated is reduced, the coverage of nickel hydroxide on the particle surface is increased, and the utilization rate of the positive electrode is improved.

The amount of the solid solution of cobalt in nickel hydroxide is preferably 0.5 to 2% by weight (a ratio of 0.5 to 2 parts by weight of cobalt to 100 parts by weight of nickel hydroxide). The amount of zinc dissolved in nickel hydroxide is preferably 0.5 to 5% by weight (a ratio of 0.5 to 5 parts by weight of zinc to 100 parts by weight of nickel hydroxide). Further, nickel hydroxide is still more preferable as long as it has a fine pore structure, and one having a peak value of the pore radius of 0.8 nm or less is preferable. The pore radius was determined by measuring a sample of 1 g at 80 ° C. and 1 × 10 ⁻³ kPa (10 × 10 ³ kPa) by a nitrogen adsorption method (Yuasa Ionics, Auto Soap 1).
The pre-treatment of vacuum suction up to × 10 ⁻³ Torr or less was performed, and the measured pore diameter was 0.1 to 10 nm (MP + BJH).
Method), measurement time 120 minutes, relative pressure (P / P ₀ ) 0.
It is expressed as a value measured on the desorption side after adsorbing nitrogen gas to 995 or more.

In the present invention, the thickness of the cobalt hydroxide particles is set to 500 by an SEM (scanning electron microscope).
The average value is obtained by selecting 10 cobalt hydroxide particles within a square of 2 μm × 2 μm at 00 × and measuring them with a ruler on an SEM photograph.

As described above, the method of coating the surface of nickel hydroxide particles with cobalt hydroxide particles includes, for example,
A solution prepared by dispersing nickel hydroxide particles produced by a known method in an aqueous alkaline solution and dissolving a predetermined amount of a cobalt compound such as cobalt sulfate or cobalt nitrate, a complexing agent such as aqueous ammonia, and an alkali for pH adjustment. Aqueous solution,
A method of coating the surface of nickel hydroxide particles with cobalt hydroxide particles by gradually adding the reaction solution while keeping the pH and temperature constant, and gradually depositing cobalt hydroxide particles on the surface of the nickel hydroxide particles. Is mentioned.

Here, the aqueous alkali solution may be a commonly used aqueous sodium hydroxide solution,
More preferably, it is a mixed solution in which an aqueous solution of sodium hydroxide is mixed with an aqueous solution of potassium hydroxide or an aqueous solution of lithium hydroxide. This means that the thickness of the cobalt hydroxide particles can be reduced to 0.025 to 0.3 by using such a mixed solution.
This is because adjustment to the range of μm becomes easy. Further, the pH of the reaction solution is preferably 10 to 13, more preferably pH 11 or more from the viewpoint of stability of the reaction conditions, and more preferably pH 12.5 or less from the viewpoint of uniformity of precipitated cobalt hydroxide particles. It is. The temperature of the reaction solution is preferably 20 to 80 ° C, more preferably 30 ° C or higher from the viewpoint of the reaction rate and the crystallinity of the precipitated cobalt hydroxide particles, and more preferably 70 ° C or lower from the stability of the reaction conditions. It is.

When the surface of the nickel hydroxide particles is coated with the cobalt hydroxide particles, the solution of the cobalt compound is added to a solution of a zinc compound, an aluminum compound, a boron compound, a calcium compound, a magnesium compound, a yttrium compound, a ytterbium compound, or the like. A solution may be added. This is because the coexistence of these elements with cobalt makes it easier to control the thickness of the cobalt hydroxide particles, or reduces the reduction resistance of higher-order cobalt oxides generated by oxidation of the cobalt hydroxide particles. This is because it can be improved.

For the positive electrode manufactured as described above, a hydrogen storage alloy is used as an active material of the negative electrode. The hydrogen storage alloy is, for example, a rare earth-Ni-based, Laves-based, or Mg-Ni-based alloy. And V-Ti-Ni-based hydrogen storage alloys. Among them, a rare earth-Ni-based hydrogen storage alloy using misch metal is preferably used. In particular, at least Ni, Co, Mn and A
l, and for a misch metal (Mm) 1, Ni,
The proportions of Co, Mn, and Al are 3.4 to 4.3, respectively.
More favorable results are obtained with alloys in the range of 0.2-0.7, 0.1-0.5, 0.1-0.4. The conductive cobalt oxide formed on the positive electrode is reduced by hydrogen gas generated by corrosion of the hydrogen storage alloy of the negative electrode or ions eluted, but the alloy having the above composition has a relatively large capacity and little corrosion. It is particularly useful for the alkaline storage battery of the invention.

For the negative electrode, for example, a conductive additive or a binder is added to the negative electrode active material comprising the above-mentioned hydrogen storage alloy, if necessary, and mixed in the presence of water or a solvent to prepare a negative electrode mixture-containing paste. (In this case, the binder may be dissolved or dispersed in water or a solvent in advance to be in a liquid state and then mixed with a negative electrode active material or the like), and then the resultant is applied to a porous base material that also functions as a current collector. The negative electrode mixture layer is formed by applying, filling, and drying to form a negative electrode mixture layer, and is formed by pressure molding as necessary. However, the method for producing the negative electrode is not limited to the method exemplified above, and may be another method. Examples of the conductive auxiliary include carbonyl nickel, carbon, and cobalt. Examples of the binder include poly-N-vinylacetamide, styrene-2-ethylhexyl acrylate copolymer, carboxymethyl cellulose, and polytetrafluorocarbon. Ethylene, styrene-butadiene copolymer and the like are used, and as the porous substrate, for example, punched metal, expanded metal, net, metal foam, and the like are used.

In the alkaline storage battery of the present invention, for example, the above-described positive electrode and negative electrode and a separator such as nylon nonwoven fabric for separating them are charged into a battery can, and an alkaline aqueous solution is injected as an electrolytic solution. Assembled to seal the can opening.

[0033]

Next, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to only those illustrated in the embodiments. In the following, “parts” means “parts by weight”, and “%” indicating a concentration is a weight unless otherwise specified.

Example 1 2 parts of cobalt hydroxide powder and 0.005 parts of magnesium oxide were added to 100 parts of nickel hydroxide powder whose surface was coated with plate-like cobalt hydroxide particles having a thickness of 0.06 μm. 10% aqueous carboxymethyl cellulose solution, 6 parts
3 parts of a 0% polytetrafluoroethylene dispersion were added and mixed to prepare a positive electrode mixture-containing paste. The obtained positive electrode mixture-containing paste is applied and filled on a porous substrate made of a nickel foam, dried at 80 ° C. for 1 hour, and then dried at 1 ton / cm ^2.
To form a sheet. This was immersed in an alkaline aqueous solution at 80 ° C. for 0.5 hour, dried in air at 80 ° C., washed with warm water at 70 ° C. for 0.7 hour, further dried at 85 ° C. for 1 hour, and then pressed. Then, it was cut into a predetermined size to obtain a non-sintered positive electrode having a theoretical capacity of 650 mAh. The content of the magnesium oxide in the positive electrode was 0.003% by weight of magnesium with respect to the weight of nickel hydroxide.

The negative electrode was manufactured as described below. Commercially available Mm (containing La, Ce, Nd, Pr), N
i, Co, Mn, Al (all purity is 99% by weight or more)
Were heat-melted by a high-frequency melting furnace so as to have a composition of MmNi _3.9 Co _0.6 Mn _0.35 Al _0.25 to obtain a hydrogen storage alloy. The hydrogen storage alloy was mechanically pulverized to obtain a hydrogen storage alloy powder having an average particle diameter of 35 μm. To 100 parts of the hydrogen storage alloy powder, 1 part of carbonyl nickel powder, 10 parts of a 5% aqueous solution of poly-N-vinylacetamide and 1.7 parts of a 40% styrene-2-ethylhexyl acrylate copolymer dispersion were added and mixed. A paste containing the negative electrode mixture was prepared. The paste containing the negative electrode mixture was applied to a porous substrate made of a punched metal made of nickel plated with nickel, filled, dried, and pressed. Then, the sheet was cut into a predetermined size to obtain a sheet-shaped negative electrode.

The above-mentioned negative electrode and positive electrode are spirally wound through a separator made of nylon non-woven fabric to form an electrode body having a wound structure, and inserted into an electrode can. , 4% of lithium hydroxide, and 4% of zinc oxide. After injecting an electrolytic solution consisting of a mixed alkaline aqueous solution, the opening of the battery can is closed, and the AAA alkaline battery having the structure shown in FIG. A storage battery was manufactured.

Here, the battery shown in FIG. 1 will be described. First, from the relationship between reference numerals and member names,
1 is a positive electrode, 2 is a negative electrode, 3 is a separator, 4 is a wound electrode body, 5 is a battery can, 6 is an annular gasket, 7 is a battery lid, 8 is a terminal plate, 9 is a sealing plate, and 10 is a metal spring. , 11 are valve bodies, 12 is a positive electrode lead body, 13 is an insulator, and 14 is an insulator.

The positive electrode 1 is composed of the non-sintered nickel electrode as described above, and the negative electrode 2 is composed of the non-sintered hydrogen storage alloy electrode as shown in FIG.
In the figures, the substrates used in their production are not shown, but are shown as a single substrate. The separator 3 is made of a nylon non-woven fabric as described above, and the positive electrode 1 and the negative electrode 2 are overlapped with the separator 3 interposed therebetween, and are wound in a spiral shape. , And an insulator 14 is disposed on the upper part thereof. At the bottom of the battery can 5, an insulator 13 is provided prior to the insertion of the wound electrode assembly 4. Although not shown in FIG. 1, the negative electrode 2
A part of the porous substrate is exposed at the outermost periphery of the battery can, and it contacts the inner wall of the battery can 5, whereby the battery can 5 acts as a negative electrode terminal.

The annular gasket 6 is made of nylon 66, the battery lid 7 is composed of a terminal plate 8 and a sealing plate 9, and the opening of the battery can 5 is sealed with the battery lid 7 or the like. That is, the wound electrode body 4 is provided inside the battery can 5 with the insulator 13,
After inserting the insulator 14 or the like, an annular groove 5a having a bottom protruding inwardly is formed in the vicinity of the opening end of the battery can 5, and after the electrolyte is injected, the above-described groove 5a is protruded inwardly. The lower portion of the annular gasket 6 is supported by the portion, and the annular gasket 6 and the battery lid 7 are arranged in the opening of the battery can 5.
The portion from a is tightened inward to seal the opening of the battery can 5. The terminal plate 8 is provided with a gas discharge port 8a, the sealing plate 9 is provided with a gas detection port 9a, and a metal spring 10 and a valve body 11 are arranged between the terminal plate 8 and the sealing plate 9. ing. Then, the outer peripheral portion of the sealing plate 9 is bent to sandwich the outer peripheral portion of the terminal plate 8, thereby fixing the terminal plate 8 and the sealing plate 9.

This battery is a metal spring 1 under normal circumstances.
Since the valve body 11 closes the gas detection port 9a by the pressing force of 0, the inside of the battery is kept in a sealed state, but gas is generated inside the battery and the pressure inside the battery rises abnormally. , The metal spring 10 contracts to form a gap between the valve body 11 and the gas detection port 9a, and gas outside the battery passes through the gas detection port 9a and the gas discharge port 8a and is discharged to the outside of the battery. When the internal pressure of the battery is reduced by the gas release, the metal spring 10 is restored to its original state, and the pressing force of the valve body 11 causes the valve 11 to return to the original state. The detection port 9a is closed to keep the outside of the battery in a sealed structure.

The positive electrode lead body 12 is made of nickel ribbon. One end of the positive electrode lead body 12 is spot-welded to the support of the positive electrode 2, and the other end is spot-welded to the lower end of the sealing plate 9. The contact with the sealing plate 9 acts as a positive electrode terminal.

Example 2 An alkaline storage battery was produced in the same manner as in Example 1 except that the amount of magnesium oxide contained in the positive electrode was changed to 1 part. The content of the magnesium oxide in the positive electrode was 0.1% by weight of magnesium with respect to the weight of nickel hydroxide.
6%.

Example 3 A positive electrode was produced in the same manner as in Example 1 except that magnesium oxide was not contained. The negative electrode is a hydrogen storage alloy 100
The same procedure as in Example 1 was carried out except that 0.05 part of magnesium oxide was contained per part. Then, an alkaline storage battery was produced in the same manner as in Example 1, except that the positive electrode and the negative electrode were used. The content of the magnesium oxide in the negative electrode was 0.03% by weight of magnesium based on the weight of the hydrogen storage alloy.

Example 4 Except that the positive electrode contained 0.5 parts of magnesium oxide based on 100 parts of nickel hydroxide and the negative electrode contained 0.1 part of magnesium oxide based on 100 parts of the hydrogen storage alloy.
An alkaline storage battery was produced in the same manner as in Example 1. The content of magnesium oxide in the positive electrode was 0.3% by weight of magnesium with respect to the weight of nickel hydroxide, and the content of magnesium oxide in the negative electrode was magnesium with respect to the weight of the hydrogen storage alloy. Weight of 0.
06%.

Comparative Example 1 The same procedure as in Example 1 was carried out except that nickel hydroxide coated on the surface with plate-like cobalt hydroxide particles having a thickness of 0.01 μm was used and magnesium oxide was not contained in the positive electrode. An alkaline storage battery was produced.

Each of the alkaline storage batteries of Examples 1 to 4 and Comparative Example 1 was stored at 70 ° C. for 6 hours, and then stored at 25 ° C.
Charge at 0.1C (70mA) for 12 hours at 0.2C
(140 mA) and discharged to 1.0 V. After repeating this charge / discharge cycle until the discharge capacity became constant, the utilization rate, charge efficiency and cycle characteristics of the positive electrode were examined. Table 1 shows the results.

The utilization rate of the positive electrode was as follows.
Charge at 5C (160mA) for 6 hours, and after 1 hour of rest,
The discharge capacity at the time of discharging to 1.0 V at 0.2 C (130 mA) was measured, and was obtained as a ratio to the theoretical capacity of the positive electrode. Table 1 shows the results.

The charging efficiency is 25 ° C., 45 ° C., 55 ° C., 6
Charge at 1.degree. C. (650 mA) at a temperature of 5.degree. C. for 1.15 hours, and after 4 hours of rest, temperature at 25.degree. C., 1 C (650 mA)
The discharge capacity at the time of discharging was measured, and the ratio to the discharge capacity at a temperature of 25 ° C. was determined. Table 1 shows the results.

The cycle characteristics were as follows: 1C at a temperature of 25 ° C.
(650 mA) for 1.2 hours, and after 10 minutes of rest, discharge at a temperature of 25 ° C. and 1 C (650 mA). This charge / discharge was repeated until the discharge capacity reached 70% of the initial discharge capacity. Was examined. Table 2 shows the results.

[0050]

[Table 1]

[0051]

[Table 2]

As shown in Table 1, the alkaline storage batteries of Examples 1 to 4 were 55 times smaller than the alkaline storage batteries of Comparative Example 1.
The charging efficiency at a high temperature of ~ 65 ° C was high, and the difference became remarkable as the temperature increased.

The alkaline storage batteries of Examples 1 to 4
The number of cycles until the discharge capacity decreased to 70% of the initial discharge capacity was large, and the cycle characteristics were excellent.

[0054]

As described above, according to the present invention, it was possible to provide an alkaline storage battery having high charge efficiency at a high temperature and excellent cycle characteristics.

[Brief description of the drawings]

FIG. 1 is a sectional view schematically showing an example of an alkaline storage battery according to the present invention.

[Explanation of symbols]

 1 positive electrode 2 negative electrode 3 separator

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H028 AA05 EE05 HH01 HH05 5H050 AA07 AA08 BA14 CA03 CB16 DA02 DA03 DA09 EA12 HA01 HA04

Claims (3)

[Claims] 1. A non-sintered positive electrode and a hydrogen storage alloy using nickel hydroxide whose surface is coated with plate-like cobalt hydroxide particles having a thickness in a range of 0.025 to 0.3 μm as an active material. An alkaline storage battery comprising a negative electrode as an active material, a separator and an electrolytic solution, wherein the non-sintered positive electrode or the negative electrode contains a magnesium compound. 2. The alkaline storage battery according to claim 1, wherein the content of the magnesium compound in the positive electrode is 0.003 to 0.6% by weight of magnesium based on the weight of nickel hydroxide. 3. The alkaline storage battery according to claim 1, wherein the content of the magnesium compound in the negative electrode is 0.003 to 0.6% by weight of magnesium based on the weight of the hydrogen storage alloy.