JP3354331B2 - Non-sintered nickel hydroxide positive electrode plate and alkaline storage battery provided with the positive electrode plate - Google Patents

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 such as a nickel-cadmium storage battery and a nickel-hydrogen storage battery, and more particularly to an improvement of a nickel hydroxide positive electrode plate.

[0002]

2. Description of the Related Art Conventionally, as a nickel hydroxide positive electrode plate for an alkaline storage battery, there is known a so-called sintered electrode plate in which a substrate obtained by sintering nickel powder into a punching metal or the like is impregnated with an active material. ing. This type of electrode has a low strength when the substrate has a high porosity, and the nickel powder falls off. Therefore, the porosity of the substrate is limited to 80% for practical use. Since such a core body is required, the packing density of the active material is small, which is disadvantageous in achieving a high energy density.

Further, the pores of the sintered substrate are as small as 10 μm or less, and the method of filling the active material has a drawback that it is limited to a solution impregnation method or an electrodeposition impregnation method that requires complicated steps.

As an attempt to remedy these drawbacks, for example, a so-called non-sintered nickel hydroxide positive plate, in which a nickel hydroxide active material is directly filled into a foamed nickel having no core and having a porosity of about 95% as a paste. There is. However, this type of electrode plate is inferior in conductivity to a sintered type electrode plate, and thus has a drawback that the active material utilization rate is low.

[0005] In order to improve the utilization rate of the active material, Japanese Patent Application Laid-Open Nos.
Japanese Patent No. 234867 proposes a method of coating the surface of nickel hydroxide particles or the surface of particles mainly composed of nickel hydroxide with a cobalt compound layer.

According to this method, a high utilization rate can be obtained even with a small addition amount of a cobalt compound. However, as the charge / discharge cycle in a battery progresses, the cobalt coating on the surface becomes nickel hydroxide. Diffusion into particles. Therefore, there is a problem that the effect of improving the conductivity of the nickel hydroxide particles by the addition of cobalt cannot be maintained for a long period of time, and the battery capacity greatly decreases as the charge / discharge cycle progresses.

On the other hand, JP-A-3-192657 discloses that a cadmium compound layer is provided on the surface of nickel hydroxide particles and a cobalt compound layer is provided thereon, or a cobalt compound layer is provided on the surface of nickel hydroxide particles. A method of providing a cadmium compound layer thereon is disclosed.

However, even in these methods,
Since the diffusion of cobalt coating the surface into the nickel hydroxide particles cannot be sufficiently prevented, there has been a problem that a decrease in battery capacity increases as the charge / discharge cycle progresses.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and suppresses the diffusion of cobalt into nickel hydroxide particles, thereby exhibiting the effect of adding a cobalt compound for a long cycle. An object of the present invention is to provide a non-sintered nickel hydroxide positive electrode plate and an alkaline storage battery provided with the positive electrode plate.

[0010]

In order to solve the above-mentioned problems, a non-sintered nickel hydroxide positive electrode plate according to the present invention is characterized in that nickel or magnesium hydroxide particles are coated with zinc or magnesium. , A first compound layer mainly containing at least one compound selected from the group consisting of aluminum and indium, and a surface of the first compound layer covered with a second compound layer mainly containing a cobalt compound. Characterized in that the particles obtained are used as an active material.

The alkaline storage battery of the present invention comprises a positive electrode, a negative electrode, and an alkaline electrolyte. The active material of the positive electrode is nickel hydroxide particles or particles having nickel hydroxide as a main component. A first compound layer mainly containing at least one compound selected from the group consisting of magnesium, aluminum and indium, and a surface of the first compound layer covered with a second compound layer mainly containing a cobalt compound; It is characterized by using coated particles.

[0012]

By providing a compound layer of at least one element selected from zinc, magnesium, aluminum and indium between the nickel hydroxide particles and the cobalt compound layer, the nickel hydroxide particles or nickel hydroxide of cobalt can be mainly used. Diffusion into particles as a component can be prevented. Therefore, the effect of improving the conductivity of the surface of the nickel hydroxide particles due to the addition of cobalt can be exhibited over a long period of time, and a decrease in capacity due to the progress of the charge / discharge cycle can be prevented.

[0013]

【Example】

(Experiment 1) The relationship between the first compound layer and the battery performance was evaluated.

(Example 1) [Preparation of active material] An aqueous solution of nickel nitrate was added to a mixed solution of an aqueous solution of sodium hydroxide and aqueous ammonia, followed by stirring and mixing, followed by filtration, washing with water, and drying. Was prepared.

At this time, the addition amounts of the aqueous nickel nitrate solution, the aqueous sodium hydroxide solution and the aqueous ammonia were adjusted so that the PH value of the whole mixed solution was maintained at about 11.

After immersing the nickel hydroxide particles in an aqueous solution of zinc nitrate, the particles are immersed in an aqueous solution of sodium hydroxide to coat the surface of the nickel hydroxide particles with a first compound layer containing a zinc compound as a main component. Furthermore, after immersing the particles in an aqueous solution of cobalt nitrate, immersing the particles in an aqueous solution of sodium hydroxide to deposit a second compound layer mainly containing a cobalt compound on the first compound layer mainly containing the zinc compound, Thereafter, washing with water, drying was carried out to give the present invention the active material powder is referred to as a _1.

The total surface layer amount was 10% by weight based on the nickel hydroxide particles, and the zinc compound amount was 20% by weight based on the cobalt compound amount.

[Preparation of non-sintered nickel hydroxide positive electrode plate]
80% by weight of the active material powder a ₁ and methyl cellulose (1
And the weight% content) aqueous solution of 20 wt% and kneaded a slurry, filling the foamed nickel, dried, and rolled to prepare a non-sintered nickel hydroxide positive electrode plate A _1.

[0019] The positive electrode plate A ₁ [Fabrication of Battery], using the alkaline electrolyte to a known sintered cadmium negative electrode plate and an aqueous solution of potassium hydroxide having a large enough electrochemical capacity for the positive electrode plate and the main Thus, an AA-size nickel-cadmium storage battery (A ₁ ) having a nominal capacity of 1000 mAh was manufactured.

Example 2 In the preparation of the active material of Example 1, the nickel hydroxide particles were immersed in an aqueous solution of magnesium nitrate instead of the aqueous solution of zinc nitrate.
Except that the surface of the nickel hydroxide particles was coated with the first compound layer containing a magnesium compound as a main component, the active material powder a _{2 of} the present invention, the positive electrode plate A _{2 of} the present invention, the battery of the present invention ( to produce a a _2).

Example 3 In the preparation of the active material of Example 1, nickel hydroxide particles were immersed in an aqueous solution of aluminum nitrate instead of an aqueous solution of zinc nitrate.
Except that the surface of the nickel hydroxide particles was coated with the first compound layer containing an aluminum compound as a main component, the active material powder a _{3 of} the present invention, the positive electrode plate A _{3 of} the present invention, the battery of the present invention ( to produce a a _3).

Example 4 In the preparation of the active material of Example 1, the nickel hydroxide particles were immersed in an aqueous solution of indium nitrate instead of an aqueous solution of zinc nitrate to form a first compound layer mainly containing an indium compound. In the same manner as in Example 1 except that the surface of the nickel hydroxide particles was coated with the above, an active material powder a _{4 of} the present invention, a positive electrode plate A _{4 of} the present invention, and a battery (A ₄ ) of the present invention were produced.

Comparative Example 1 In the preparation of the active material of Example 1, the nickel hydroxide particles were immersed in an aqueous solution of cadmium nitrate instead of an aqueous solution of zinc nitrate to form a first compound layer mainly composed of a cadmium compound. Comparative Active Material Powder x, Comparative Positive Electrode Plate X, and Comparative Battery (X) were prepared in the same manner as in Example 1 except that the surface of the nickel hydroxide particles was coated with.

(Comparative Example 2) On the surface of nickel hydroxide particles,
Comparative active material powder y having only a cobalt compound layer was prepared. A comparative positive electrode plate Y and a comparative battery (Y) were produced in the same manner as in Example 1 except that this active material powder was used.

[Measurement of Cycle Characteristics of Batteries] Each of the batteries was charged at a current of 100 mA for 16 hours,
The cycle of discharging until the current A reaches 1.0 V was repeated, and the battery capacity was measured. The result is shown in FIG. The horizontal axis in FIG. 1 indicates the number of cycles, and the vertical axis indicates the battery capacity.

The battery capacity of each battery was indicated by an index when the discharge capacity at the first cycle was 100.

As is clear from FIG. 1, the capacity of the comparative battery (Y) using the material having only the cobalt compound layer formed on the surface of the nickel hydroxide particles as the active material has the greatest reduction in charge-discharge cycle.

This is because cobalt added to the surface of the active material diffuses into the nickel hydroxide particles.

Further, the surface of the nickel hydroxide particles is coated with a first compound layer mainly containing a cadmium compound, and the first compound layer is coated with a second compound layer mainly containing a cobalt compound. Battery (X) used as a battery
As for the battery of the present invention (A ₁ ), although the decrease in capacity with the progress of the charge / discharge cycle is smaller than that of the comparative battery (Y),
(A ₄ ), the decrease in the battery capacity is large. This is, rather than coating the surface of the nickel hydroxide particles with a layer mainly containing a cadmium compound, zinc, magnesium,
At least one selected from aluminum and indium
It is better to coat with a layer mainly composed of compounds of the various elements
It is considered that this is because the effect of preventing cobalt added to the active material surface from diffusing into the nickel hydroxide particles is more exhibited.

(Experiment 2) The relationship between the ratio of the first compound layer to the second compound layer covering the nickel hydroxide particles and the battery performance was evaluated.

[Preparation of Active Material] In the same manner as in Example 1, the total surface layer amount was fixed at 10% by weight with respect to the nickel hydroxide particles, and the zinc compound relative to the cobalt compound amount (second compound layer) was used. Amount (first compound layer) 0.3, 0.5,
To prepare an active material powder was varied 10,30,50,70 wt%, referred to respectively _{a 5, a 6, a 7} , a 8, a 9, a 10.

[Preparation of non-sintered nickel hydroxide positive electrode plate]
80% by weight of each of the active material powders and 20% by weight of an aqueous solution of methylcellulose (containing 1% by weight) are kneaded to form a slurry. did.

A positive plate using each of the above-mentioned active material powders a _{5 to} a ₁₀ was prepared as A ₅ , A ₆ , A ₇ , A ₈ , A
_9, referred to as the A _10.

[Preparation of Battery] Each of the positive plates A _{5 to} A _5
10 and a known sintered cadmium negative electrode plate having a sufficiently large electrochemical capacity with respect to this positive electrode plate and an alkaline electrolyte mainly composed of an aqueous solution of potassium hydroxide. A cadmium storage battery is manufactured, and each (A ₅ )
(A ₆ ), (A ₇ ), (A ₈ ), (A ₉ ) and (A ₁₀ ). Also, as a comparison, a battery (Y) using the active material powder y
Was prepared.

[Measurement of Cycle Characteristics of Battery] Experiment 1
The cycle characteristics of the battery were measured in the same manner as described above, and the results are shown in FIG. The horizontal axis in FIG. 2 indicates the number of cycles, and the vertical axis indicates the battery capacity.

The battery capacity of each battery was indicated by an index with the discharge capacity at the first cycle being 100.

FIG. 2 shows that the battery (A) provided with the active material in which the amount of the zinc compound relative to the amount of the cobalt compound was 0.3% by weight.
₅ ) The batteries (A ₆ ) to which the amount of the zinc compound is 0.5% by weight or more with respect to the amount of the cobalt compound are smaller than those of the comparative battery (Y), although the decrease in the battery capacity with the progress of the charge and discharge cycle is smaller.
Compared with (A ₁₀ ), the decrease in battery capacity increases with the progress of the charge / discharge cycle.

This shows that it is preferable to use an active material in which the amount of the zinc compound is 0.5% by weight or more based on the amount of the cobalt compound.

[Measurement of Active Material Utilization Rate] FIG.
Shows the result of calculating the utilization of the active material powder a ₅ ~a _10, y from the battery capacity cycle. The horizontal axis in FIG. 3 shows the ratio of the zinc compound amount to the cobalt compound amount, and the vertical axis shows the utilization.

The utilization rate is indicated by an index with the active material powder y being 100.

FIG. 3 shows that when the amount of the zinc compound exceeds 50% by weight with respect to the amount of the cobalt compound, the utilization factor decreases. Therefore, the amount is preferably 50% by weight or less.

From the above results, it is found that the range of the zinc compound amount (first compound layer) is preferably 0.5% by weight or more and 50% by weight or less with respect to the cobalt compound amount (second compound layer).

(Experiment 3) The relationship between the total surface layer amount for nickel hydroxide particles and the battery characteristics was evaluated.

[Preparation of Active Material] In the same manner as in Example 1, the amount of zinc compound (first compound layer) was fixed at 20% by weight based on the amount of cobalt compound (second compound layer), and the total surface layer amount was fixed. With respect to the nickel hydroxide particles
The active materials were changed to 0, 25, and 30% by weight, respectively.

[Preparation of non-sintered nickel hydroxide positive electrode plate]
80% by weight of each of the active material powders and 20% by weight of an aqueous solution of methylcellulose (containing 1% by weight) are kneaded to form a slurry. did.

[Preparation of Battery] Each of the above positive electrode plates, a known sintered cadmium negative electrode plate having a sufficiently large electrochemical capacity for the positive electrode plate, and an alkaline electrolyte mainly composed of a potassium hydroxide aqueous solution were used. , Each with a nominal capacity of 1000 mAh
AA size nickel-cadmium storage battery was manufactured.

[Measurement of Active Material Utilization] FIG. 4 shows the result of calculating the utilization of each active material powder from the battery capacity at the 10th cycle. The horizontal axis of FIG. 4 indicates the ratio of the total surface layer amount to the nickel hydroxide particles, and the vertical axis indicates the utilization.

As is clear from FIG. 4, the effect of improving the utilization factor appears when the total surface layer amount is 3% by weight or more with respect to the nickel hydroxide particles, and when the total surface layer amount exceeds 25% by weight, the ratio of nickel hydroxide decreases. Since the accompanying reduction in utilization is observed, the total surface layer amount is suitably 3 to 25% by weight.

In Experiments 2 and 3, a zinc compound layer was used as the first compound layer. However, a similar effect can be obtained in a magnesium compound layer, an aluminum compound layer, an indium compound layer, or a mixed compound layer thereof. Can be

In the present embodiment, nickel hydroxide particles containing no zinc, cobalt, cadmium, magnesium, aluminum, etc. were used. The same effect can be obtained when using particles mainly composed of nickel hydroxide in which seeds are dissolved in the particles.

In this embodiment, the surface of the nickel hydroxide particles is composed of two layers such as a zinc compound layer and a cobalt compound layer. However, the present invention is not limited to this. For example, a zinc compound layer-a magnesium compound layer- Similar effects can be expected for three or more layers such as a cobalt compound layer.

[0052]

As is apparent from the above, the surface of the nickel hydroxide particles is coated with a first compound layer containing at least one compound selected from the group consisting of zinc, magnesium, aluminum and indium as a main component, By coating the surface of the first compound layer with a second compound layer containing a cobalt compound as a main component, it has a high capacity and suppresses the diffusion of cobalt added to the surface into the nickel hydroxide particles, thereby providing a long-term treatment. Since the effect of adding cobalt can be exerted over a cycle, an alkaline storage battery having excellent cycle characteristics can be provided.

[Brief description of the drawings]

FIG. 1 is a cycle characteristic diagram of a battery.

FIG. 2 is a cycle characteristic diagram of a battery.

FIG. 3 is a graph showing the relationship between the weight ratio of a zinc compound to a cobalt compound and utilization.

FIG. 4 is a graph showing the relationship between the weight ratio of the entire surface layer to nickel hydroxide particles and the utilization.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-242886 (JP, A) JP-A-3-78965 (JP, A) JP-A-50-136645 (JP, A) 77273 (JP, A) JP-A-3-274666 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01M 4/32 H01M 4/52 H01M 10/30

Claims (6)

(57) [Claims] 1. A surface of a nickel hydroxide particle or a particle mainly containing nickel hydroxide as a first compound layer mainly containing at least one compound selected from the group consisting of zinc, magnesium, aluminum and indium. A non-sintered nickel hydroxide positive electrode plate, characterized in that particles coated and coated on the surface of the first compound layer with a second compound layer containing a cobalt compound as a main component are used as an active material. 2. The non-sintering method according to claim 1, wherein the weight of the first compound layer is 0.5% by weight or more and 50% by weight or less based on the weight of the second compound layer. Nickel hydroxide positive electrode plate. 3. The total weight of the first compound layer and the second compound layer is not less than 3% by weight and not more than 25% by weight based on the nickel hydroxide particles or particles containing nickel hydroxide as a main component. 2. The non-sintered nickel hydroxide positive electrode plate according to claim 1, wherein: 4. An alkaline storage battery provided with a positive electrode, a negative electrode, and an alkaline electrolyte, wherein, as an active material of the positive electrode, nickel hydroxide particles or particles containing nickel hydroxide as a main component are made of zinc, magnesium, aluminum, or indium. Particles coated with a first compound layer containing at least one compound selected from the group consisting of a main component and the surface of the first compound layer coated with a second compound layer containing a cobalt compound as a main component are used. An alkaline storage battery characterized by the following. 5. The alkaline storage battery according to claim 4, wherein the weight of the first compound layer is 0.5% by weight or more and 50% by weight or less based on the weight of the second compound layer. 6. The total weight of the first compound layer and the second compound layer is not less than 3% by weight and not more than 25% by weight based on the nickel hydroxide particles or particles containing nickel hydroxide as a main component. The alkaline storage battery according to claim 4, characterized in that: