JP3183073B2 - Active material for nickel electrode and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to alkaline batteries such as nickel-cadmium batteries, and more particularly to alkaline batteries such as nickel-cadmium batteries.
The present invention relates to a nickel electrode for an alkaline battery and a nickel active material.

[0002]

2. Description of the Related Art In recent years, the integration of various electronic devices into integrated circuits has progressed, and the size and weight of electronic devices have been rapidly reduced. For this reason, the portability of the electronic device has been improved, and the power supply unit for supplying power to the electronic device has been increasingly wired. At present, a nickel-alkali battery using a nickel electrode as a positive electrode has been used as a power supply for supplying power at the time of dressing because of its excellent characteristics. However, as electronic devices become smaller and lighter, the proportion of the battery, which is a power supply unit, to the constituent weight and volume of the electronic device is increasing. Therefore, in order to further reduce the size and weight of electronic devices, increasing the capacity of batteries has become an important issue. For this reason, the nickel-alkali battery electrode has come to use a nickel electrode which is formed by filling a concave portion of a nickel porous body with various active materials, drying, and then press-molding the electrode. No. 49-127145). However, even the nickel-alkali batteries manufactured in this manner have not sufficiently responded to the demand for higher capacity in the market, and nickel-alkali batteries with higher capacities have been demanded.

It is said that the deterioration of the life of the nickel electrode constituting the nickel-alkali battery is mainly caused by the swelling of the nickel electrode and the formation of partial protrusions (blisters). Further, it is generally considered that the swelling of the nickel electrode is caused by a change in volume of the nickel hydroxide active material in the nickel electrode. The nickel hydroxide active material is manufactured in the form of a powder as described in, for example, Japanese Patent Application Laid-Open No. 5-254847, so as to fill the concave portions of the porous body as described above. When a nickel-alkali battery repeats normal charge and discharge, nickel hydroxide in a nickel electrode changes from β-Ni (OH) ₂ to β-Ni
OOH, and conversely, β-NiOOH
To β-Ni (OH) ₂ .

When only the above reaction is repeated,
A change in volume of the nickel electrode is unlikely to occur. However, while the nickel-alkali battery repeats charging and discharging, a locally uneven current density may be generated inside the nickel electrode, thereby causing a higher oxide γ-NiOOH. Comes out. γ-Ni
When a nickel alkaline battery discharges, a part of OOH changes to β-Ni (OH) ₂ , but most of it changes to very low density α-Ni (OH) ₂ . Then, when γ-NiOOH is generated, the density of the nickel electrode becomes low due to repetition of charging and discharging, and the density cannot be restored. This phenomenon is
The more the charge and discharge repeat, the worse it gets,
As a result, the electrodes swell. In order to reduce the swelling of the nickel electrode generated as described above,
A method is disclosed in which a buffer space capable of absorbing swelling is provided in a nickel electrode so that swelling of the nickel hydroxide active material does not directly lead to swelling of the nickel electrode. However, in this case, as a result, the packing density of the nickel hydroxide active material was reduced, and consequently, the capacity of the nickel electrode was reduced.

On the other hand, attempts have been made to control the production of γ-NiOOH itself, and it has been found that the addition of Cd is effective for this purpose. More recently, Cd
In addition, it has been reported that the same effect can be obtained by adding Zn or Mg. (Battery Handbook, Maruzen Co., Ltd., published on August 20, 1990, p. 233) Since the crystal lattice of nickel hydroxide is distorted by these added elements, H ⁺ It is said that the mobility in the nickel hydroxide lattice is improved and the generation of γ-NiOOH is suppressed. In order for Zn to exhibit such a swelling suppressing effect, as described in JP-B 2-30061, 3% by weight or more (3 to 10% by weight) of zinc is solidified in nickel hydroxide crystals. Must be in molten state. However, a swelling suppressing element such as Zn only suppresses swelling of the electrode, and does not directly participate in the battery reaction. Therefore, when such a swelling-inhibiting element is added, the amount of addition is relatively large, so that the nickel quality directly involved in the battery reaction in nickel hydroxide is reduced, and the capacity of the nickel electrode is reduced. In other words, as the nickel grade of the nickel hydroxide active material approaches 63.3% by weight of the theoretical grade, the capacity of the nickel electrode becomes:
However, the addition of the swelling-inhibiting element does not bring it close to the theoretical grade. That is, as long as the swelling of the nickel electrode can be suppressed, the smaller the addition amount of the swelling suppressing element such as Zn, the better. The addition of zinc and yttrium to nickel hydroxide is disclosed in Japanese Patent Application Laid-Open No. 5-28992, but the nickel hydroxide contains 1 to 7% of zinc and yttrium, and the capacity and swelling of the nickel electrode are increased. Suppression is not associated.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a nickel
Energy density is reduced by suppressing the production of γ-NiOOH, which is said to be a factor that hinders the life of a nickel electrode used in an alkaline battery, and by increasing the nickel grade compared to a conventional nickel hydroxide active material. It is an object of the present invention to provide an active material for a nickel electrode, which has a higher level, a method for producing the same, and a nickel electrode using the same.

[0007]

According to the present invention, a nickel alloy is used.
An active material of a nickel electrode constituting an alkaline battery is composed of nickel hydroxide as a main component, zinc, and 0.1 to 1% by weight.
Lanthanoid element and / or yttrium and / or scandium. 0.5% by weight of zinc
It is preferably at least 3% by weight. In this case, it is preferable that zinc, a lanthanoid element, yttrium, and scandium are simultaneously added to nickel hydroxide by stirring granulation or the like, and the total amount is less than 3% by weight. It is desirable that these elements are in a solid solution state in the nickel hydroxide crystal. In addition, the average particle size of the active material for a nickel electrode is 5-10.
It is preferably 0 μm.

[0008] The nickel electrode of the present invention comprises nickel hydroxide, zinc,
It is filled with an active material for a nickel electrode composed of 0.1 to 1% by weight of a lanthanoid element and / or yttrium and / or scandium. Zinc is 0.
It is preferably at least 5% by weight and less than 3% by weight. It is preferable that zinc and a lanthanoid element, yttrium, and scandium are added at the same time, the total amount is less than 3% by weight, and the solid solution is in a solid solution state in the nickel hydroxide crystal. In this case, as the porous alkali-resistant metal substrate, a sponge-like nickel porous body obtained by subjecting a resin sponge to nickel plating, roasting and refining the same is preferred.

[0009]

According to the present invention, the nickel electrode active material used for the nickel electrode constituting the nickel-alkali battery is:
This is a nickel hydroxide active material containing nickel hydroxide as a main component and zinc and 0.1 to 1% by weight of a lanthanoid element, yttrium and scandium added simultaneously to stirring granulation or the like. Zinc is preferably 0.5 to 3% by weight, and the total amount of zinc, lanthanoid element, yttrium, and scandium is preferably less than 3% by weight. Zinc, a lanthanoid element, yttrium, and scandium contained in the nickel hydroxide crystal give distortion to the nickel hydroxide crystal. In particular, by adding a lanthanoid element or yttrium together with zinc as compared with the case where only zinc is added, crystal distortion is further imparted, and a similar effect of suppressing swelling can be obtained with a lower added element amount. For this purpose, these elements are desirably stirred and granulated, and more preferably in a solid solution state.

The lanthanoid element and yttrium are usually trivalent, and when replaced with the nickel element in the nickel hydroxide crystal, become a donor and emit electrons to improve the conductivity of the nickel hydroxide active material. Is also conceivable. Due to such an effect, the degree of freedom of the action of protons and electrons in the crystal is increased, and as a result, the production of γ-NiOOH is suppressed, and the same effect can be obtained with a smaller amount of element than the conventional nickel electrode to which only zinc is added. An effect of suppressing swelling is obtained. In the case of a nickel hydroxide active material to which only zinc is added, addition of 3% by weight or more is required to suppress swelling, and the nickel grade in the nickel hydroxide active material is 5%.
7 to 58% by weight. However, in the present invention, since 0.5% by weight of zinc and 0.5% by weight of a lanthanoid element or yttrium also exert a swelling suppressing effect, the nickel grade in the nickel hydroxide active material is 60 to 62% by weight. %, And the nickel grade is increased by 3 to 5% by weight, as compared with the conventional alloy containing only zinc. The increase in the nickel grade in the nickel hydroxide active material means that the amount of the electrochemical reaction in the nickel hydroxide active material per unit weight increases.

By using the nickel electrode active material of the present invention, 4 to 6% more electricity can be taken out per unit weight than can be taken out from the conventional nickel hydroxide active material, and the electric capacity of the nickel electrode can be obtained. To increase the capacity of the battery. In the case of the present invention, the amount of the lanthanoid element, yttrium or scandium added to the nickel hydroxide active material is 0.05 to 1% by weight, and the concentration of zinc added is 0.5 to 3% by weight. Is preferred. This is because when the lanthanoid element or yttrium added to the nickel hydroxide active material is 0.1% by weight or less, the effect of suppressing the swelling of the nickel electrode is not sufficiently exerted. Is desirably 0.5% by weight or more of zinc. Conversely, if the amount of zinc exceeds 3% by weight, the nickel grade in the nickel hydroxide active material is only zinc while the swelling suppressing effect is not improved at all. The addition of lanthanoid elements, yttrium, and scandium causes the lanthanoid element, yttrium, and scandium to be distorted because the addition of lanthanoid elements, yttrium, and scandium exceeds 1% by weight. This is because the density of the nickel oxide active material particles is reduced, and the electric capacity of the nickel electrode is reduced.

When the lanthanoid element, yttrium, scandium, and zinc are in a solid solution state in the nickel hydroxide crystal, it is possible to avoid a decrease in the density of the nickel hydroxide particles due to their deflection, and to effectively reduce the crystal distortion. Can be generated. The nickel electrode active material has a more preferable result when the average particle diameter is 5 to 100 μm. Average particle size is 5μ
If it is smaller than m or larger than 100 μm, the filling properties of the porous substrate carrying the active material into the recesses will be poor. That is, it is smaller than the concave portion of the porous substrate and drops, or larger than the concave portion and cannot be filled. Further, in the present invention, in the concave portion of the porous alkali-resistant metal substrate, 0.1 to 1% by weight of a lanthanoid element, yttrium, scandium and zinc in a total amount of 3 to 1% by weight, mainly containing nickel hydroxide.
The present invention provides a nickel electrode filled with an active material for a nickel electrode added in less than% by weight, thereby enabling the electric capacity of a battery to be increased.

In the case of the present invention, the porous alkali-resistant metal plate is a sponge-like nickel porous body obtained by subjecting a resin sponge to nickel plating, roasting and refining the sponge. Increase electric capacity. In the present invention, the average space diameter of the porous alkali-resistant metal substrate constituting the nickel electrode may be 100 μm to 100 μm.
By filling the space (concave portion) with particles of the nickel hydroxide active material together with cobalt or nickel powder, the capacity of the nickel battery can be further increased. However, the reason has not been elucidated. In the present invention,
The lanthanoid element added to the nickel hydroxide active material means an element included in the lanthanoid series that starts with lanthanum and ends with ruthenium in the periodic table of the elements. When the lanthanoid element, yttrium, and scandium are added simultaneously with zinc to the nickel hydroxide active material, good results are shown even when one or more of these elements coexist. It is.

[0014]

Embodiments of the present invention will be described in detail below. (Example 1) An aqueous solution prepared by adding lanthanum nitrate and zinc sulfate to a nickel sulfate solution was prepared, and ammonia water was added dropwise to this solution to form an ammine complex ion of nickel. By vigorously stirring while dropping the solution, the complex ions were decomposed, and the nickel hydroxide particles in which zinc and lanthanum were made into a solid solution were gradually deposited. The above-mentioned nickel hydroxide particles in which zinc and lanthanum are made into a solid solution are washed with water to remove anions and sodium ions adhering to the surface thereof, and then the amount of zinc added is reduced to 2 using a stirring granulator. Nickel hydroxide particles having an average particle size of 5 μm, which was 0.0% by weight, the amount of lanthanum added was 0.5% by weight, and the Ni grade was 60.2%, were granulated. The tap density of the nickel hydroxide particles was 2.0 g / ml.

On the other hand, a porous alkali-resistant metal substrate is nickel-plated on a resin sponge, and is roasted.
The sponge-like nickel porous body obtained by refining was used. 50 parts by weight of the above nickel hydroxide particles, 45 parts by weight of nickel powder,
A nickel electrode was prepared by filling 5 parts by weight of the cobalt powder and a paste containing carboxymethyl cellulose as a thickener, drying and compressing. The nickel electrode is used as a positive electrode, and a cadmium electrode having an excess capacity as compared with the positive electrode is provided as a negative electrode. A glass bipolar electrode partitioned by a glass filter is used, and a concentration of 30% by weight is used. An open model cell was assembled using an aqueous solution of potassium hydroxide as an electrolyte.

After performing a charging process in which a current equivalent to 0.1 C is applied to the model cell for 12 hours,
The battery was discharged to 1.0 V at a current corresponding to C. Thereafter, the battery is charged for 5 hours at a current equivalent to 1C, and charged at a current equivalent to 1C for 1.0 hour.
Discharged to V. After discharging, the thickness of the electrode is measured, the swelling amount of the electrode is determined by comparing the thickness with the electrode thickness before charging, and the discharge capacity is measured. And the utilization factor as a nickel electrode active material was calculated. Hereinafter, the expansion rate presented as a series of measured values is indicated by a value (× 100) obtained by dividing the thickness of the electrode after charging by the thickness of the electrode before charging. The swelling ratio of the nickel electrode measured in Example 1 was 10
3%, and the utilization rate of the nickel electrode active material was 8%.
It was calculated to be 6%.

(Example 2) The amount of zinc added was 1.0% by weight.
An open model cell was assembled in the same manner as in Example 1 except that nickel hydroxide particles (average particle size: 12 μm) having a Ni grade of 61.0% were used, and charging and discharging were performed in the same manner as in Example 1. As a result, the tap density of the nickel hydroxide particles was 2.01 g / ml, the utilization rate of the active material was 86%, and the swelling rate of the nickel electrode was 105%.

Example 3 The amount of zinc added was 0.5% by weight.
Then, an open model cell was assembled in the same manner as in Example 1 except that nickel hydroxide having a nickel grade of 61.0% (average particle size: 20 μm) was used, and charge and discharge were performed in the same manner as in Example 1. As a result of repeated measurements, the tap density of nickel hydroxide was 2.01 g / ml, the utilization rate of the active material was 84%, and the swelling rate of the electrode was 110%.

Example 4 The procedure of Example 1 was repeated, except that the amount of lanthanum added was 0.1% by weight, and nickel hydroxide having a Ni grade of 60.1% (average particle size 8 μm) was used. As a result of assembling an open model cell and measuring while repeating charging and discharging in the same manner as in Example 1, the tap density of nickel hydroxide was 2.00 g / ml, the utilization rate of the active material was 86%, and the electrode The swelling ratio was 112%.

(Example 5) The amount of lanthanum added was 0.1% by weight, the amount of zinc added was 0.5% by weight, and the Ni grade was 6%.
An open system model cell was assembled in the same manner as in Example 1 except that 1.5% of nickel hydroxide (average particle size: 9 μm) was used, and the results were measured while repeating charging and discharging as in Example 1. The tap density of nickel hydroxide is 2.0
5 g / ml, the utilization rate of the active material was 83%, and the swelling rate of the electrode was 120%.

Example 6 Nickel hydroxide to which 0.5% by weight of cerium was added instead of lanthanum (average particle size of 7%)
An open model cell was assembled in the same manner as in Example 1 except that μm) was used, and measurement was performed while repeating charging and discharging in the same manner as in Example 1. As a result, the tap density of nickel hydroxide was 2.00 g / ml and the utilization rate of the active material is 8
6%, and the swelling ratio of the electrode was 104%.

Example 7 In place of lanthanum, 0.5% by weight of praseodymium was added, and Ni grade was 60.1%.
% Of nickel hydroxide (average particle size: 11 μm), an open model cell was assembled in the same manner as in Example 1, and the measurement was performed while repeating charge and discharge in the same manner as in Example 1. Nickel tap density is 2.00g
/ Ml, the utilization rate of the active material was 86%, and the swelling rate of the electrode was 105%.

Example 8 In place of lanthanum, 0.5% by weight of praseodymium was added, the amount of zinc added was increased to 2.5% by weight, and nickel grade was 60.1% nickel hydroxide (average particle size: 10 μm ) Was used to assemble an open model cell in the same manner as in Example 1, and the charging and discharging were repeated and measured in the same manner as in Example 1. As a result, the tap density of nickel hydroxide was 2.00 g / ml. The utilization rate of the active material was 86%, and the swelling rate of the electrode was 105%.

Example 9 The procedure of Example 1 was repeated except that 0.5% by weight of neodymium was added instead of lanthanum, and nickel hydroxide having a Ni grade of 60.1% (average particle size: 8 μm) was used. An open model cell was assembled in the same manner, and the measurement was performed while repeating charging and discharging as in Example 1. As a result, the tap density of nickel hydroxide was 2.00 g / ml, and the utilization rate of the active material was 84%. And the electrode swelling ratio is 104
%Met.

Example 10 Instead of lanthanum, 0.5
An open model cell was assembled in the same manner as in Example 1 except that nickel hydroxide (average particle size: 7 μm) to which wt% ytterbium was added, and measurement was performed while repeating charge and discharge as in Example 1. As a result, the tap density of nickel hydroxide was 2.00 g / ml, the utilization rate of the active material was 83%, and the swelling rate of the electrode was 106%.

(Example 11) Instead of lanthanum, 0.5
Weight percent yttrium, Ni grade 60.3%
An open model cell was assembled in the same manner as in Example 1 except that nickel hydroxide (average particle size: 11 μm) was used, and measurement was performed while repeating charging and discharging in the same manner as in Example 1. Has a tap density of 1.98 g /
ml, the utilization rate of the active material was 87%, and the swelling rate of the electrode was 104%.

Example 12 Instead of lanthanum, 0.1
An open type model cell was assembled in the same manner as in Example 1, except that neodymium was added in an amount of 0.8% by weight, and nickel hydroxide having a Ni grade of 60.8% (average particle size: 13 μm) was used. As a result of measurement while repeating charge and discharge, the tap density of nickel hydroxide was 2.06 g /
ml, the utilization rate of the active material was 84%, and the swelling rate of the electrode was 114%.

(Example 13) The amount of lanthanum added was 0.7
An open type model cell was assembled in the same manner as in Example 1 except that nickel hydroxide (average particle size: 7 μm) having a Ni grade of 60.1% by weight was used, and charging and charging were performed in the same manner as in Example 1. As a result of measurement while repeating discharge, the tap density of nickel hydroxide was 2.01 g / ml, the utilization rate of the active material was 83%, and the swelling rate of the electrode was 104%.

Comparative Example 1 The procedure of Example 1 was repeated except that the amount of lanthanum was 1.1% by weight and nickel hydroxide having a nickel grade of 58.7% (average particle size: 6 μm) was used. As a result of assembling an open model cell and repeating charging and discharging in the same manner as in Example 1, the tap density of nickel hydroxide was 1.85 g / ml, the utilization rate of the active material was 75%, and the electrode The swelling ratio was 104%.

Comparative Example 2 The amount of lanthanum was 0.08
Wt.%, And an open model cell was assembled in the same manner as in Example 1 except that nickel hydroxide having a nickel grade of 60.5% (average particle size: 9 μm) was used. As a result of measurement while repeating discharge, the tap density of nickel hydroxide was 2.05 g / ml, the utilization rate of the active material was 84%, and the swelling rate of the electrode was 128%.

Comparative Example 3 Without adding a lanthanoid element or yttrium, only 2.0% by weight of zinc was added.
Nickel hydroxide with Ni grade of 60.3% (average particle size 11
An open system model cell was assembled in the same manner as in Example 1 except that μm) was used, and measurement was performed while repeating charge and discharge in the same manner as in Example 1. As a result, the tap density of nickel hydroxide was 2.08 g / ml and the utilization rate of the active material is 8
6% and the swelling ratio of the electrode was 130%.

Comparative Example 4 Without adding a lanthanoid element or yttrium, only 3.1% by weight of zinc was added.
Nickel hydroxide with Ni grade of 57.9% (average particle size 6μ)
An open model cell was assembled in the same manner as in Example 1 except that m) was used, and the charging and discharging were repeated and measured as in Example 1. As a result, the tap density of nickel hydroxide was 2.03 g / ml, and the utilization rate of the active material is 86
%, And the swelling ratio of the electrode was 110%.

Table 1 shows the results of the above Examples and Comparative Examples.

[0034]

[Table 1] Ni tap density, such as Zn La, swelling utilization factor, average particle size (% by weight) (g / ml) (%) (%) (μm) Example 1 2.0 La 0.5 60.2 2.00 103 86 65 21.0 La 0.5 61.0 2.01 105 86 12 3 0.5 La 0.5 61.0 2.01 110 84 204 42.0 La 0.1 60.1 2.00 112 86 80.5 0.5 La 0.1 61.5 2.05 120 839 62.0 Ce 0.5 60.2 2.00 104 86 7 7 2.0 Pr 0.5 60.1 2.00 105 86 11 8 2.5 La 0.5 60.0 2.04 103 86 69 9 Nd 0.5 60.1 2.00 104 84 8 10 2.0 Ib 0.5 60.2 2.00 106 83 7 11 2.0 Y 0.5 60.3 1.98 104 87 11 12 2.0 Nd 0.1 60.8 2.06 114 84 13 13 2.0 La 0.7 60.1 2.01 104 837 Comparative Example 1 2.0 La 1.1 58.7 1.85 104 75 6 22.0 La0.08 60.5 05 128 84 9 3 2.0-60.3 2.08 130 86 11 4 3.1-57.9 2.03 110 86 6

[0035]

As described above, the active material for a nickel electrode and the nickel electrode according to the present invention are constituted as described above.
-The generation of NiOOH can be suppressed, and the energy density can be increased by increasing the nickel quality as compared with the conventional nickel hydroxide active material.

Claims (9)

(57) [Claims] 1. A nickel hydroxide active material constituting a nickel electrode of an alkaline battery comprises 0.1 to 1% by weight of a lanthanoid element, zinc, and substantially the balance of nickel hydroxide. 3% by weight of total zinc
An active material for a nickel electrode. 2. The method according to claim 1, wherein the nickel hydroxide active material constituting the nickel electrode of the alkaline battery comprises 0.1 to 1% by weight of a lanthanoid element and / or yttrium and / or scandium, and 0.5% to less than 3% by weight. Of zinc and substantially the remainder of nickel hydroxide, and the total amount of the lanthanoid element, yttrium, and scandium is 3
An active material for a nickel electrode, which is less than 10% by weight. 3. The active material for a nickel electrode according to claim 1, wherein nickel hydroxide is granulated with stirring together with a lanthanoid element and / or yttrium and / or scandium and zinc. 4. The method according to claim 1, wherein the lanthanoid element is La, Ce, Pr,
The active material for a nickel electrode according to claim 1, wherein the active material is at least one of Nd and Yb. 5. The nickel hydroxide active material has an average particle size of 5 μm.
2. A particle having a particle size of m to 100 [mu] m.
4. The active material for a nickel electrode according to any one of claims 1 to 3. 6. The method according to claim 6, wherein the concave portions of the porous alkali-resistant metal substrate are
5. A nickel electrode, wherein the nickel electrode active material according to claim 1 is filled together with nickel powder and cobalt powder. 7. The nickel electrode according to claim 5, wherein the porous alkali-resistant metal substrate is a sponge-like nickel porous body obtained by subjecting a resin sponge to nickel plating, roasting and refining the sponge. 8. The concave portion of the porous alkali-resistant metal substrate,
The nickel electrode according to claim 5, having an average diameter of 100 μm to 1000 μm. 9. A lanthanoid element and / or yttrium and a solid solution of zinc with respect to nickel hydroxide, and 0.1 to 1% by weight of the lanthanoid element and / or yttrium, and 0.5 to 3% by weight. A method for producing a nickel electrode active material for forming a particulate nickel hydroxide active material containing zinc.