JPH097585A - Nickel hydride battery and manufacture thereof - Google Patents

Abstract

PURPOSE: To suppress increasing an internal pressure of a battery by providing a rich layer of containing a transition metal element with large ratio in a surface part as compared with an internal part of a hydrogen absorbing alloy grain, so that electrode reaction can be efficiently performed from the initial period of charge/discharge. CONSTITUTION: A hydrogen absorbing alloy having a composition of MmNi3.8 Al0.3 Co0.7 Mn0.2 is measured, input to a crucible and melted by a high frequency melting furnace under an inactive atmosphere, to prepare an ingot. This alloy ingot is crushed into a grain of suitable size by mechanical crushing or hydride crushing, to obtain a hydrogen absorbing alloy grain. As a first process, the alloy grain is immersed in an acetic acid-sodium acetate buffer solution adjusted to 60 deg.C pH3.6, stirred and dried after washing by water. In this state, electron beam analysis is performed, to produce a rich layer 2 in a surface part of the alloy grain. In the rich layer 2, having large containing ratio of a transition metal element of Ni or the like as compared with bulk 1, electrode reaction can be efficiently performed, to suppress increasing an internal pressure by accumulating hydrogen gas.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a long-life and high-performance nickel hydride battery and a method for manufacturing the battery.

[0002]

2. Description of the Related Art Nickel hydride batteries using a hydrogen storage alloy capable of electrochemically storing and releasing hydrogen as a negative electrode active material have higher energy density and lower pollution than conventional nickel cadmium batteries. Being sex,
Expected as a power source for portable devices and electric vehicles,
In recent years, research and development have been actively conducted.

By the way, in the nickel hydride battery, the negative electrode capacity is set to be larger than the positive electrode capacity, so that the oxygen gas generated in the positive electrode during overcharge is combined with hydrogen in the negative electrode to become water. And, by this, the sealing is established. By the way, until the oxygen gas generated in the positive electrode is consumed in the negative electrode and becomes water, the oxygen gas accumulates inside the battery and the internal pressure of the battery rises. If the consumption of oxygen gas in the negative electrode is slow, the internal pressure of the battery rises significantly, the internal pressure exceeds the safety valve operating pressure, and oxygen gas is released to the outside of the battery. When oxygen gas is released to the outside of the battery, the amount of the electrolytic solution decreases, which causes an increase in internal resistance and shortens the battery life.

Further, in general, since the difference between the charging potential of the hydrogen storage electrode (that is, the hydrogen storage potential) and the hydrogen generation potential is small, hydrogen gas is a side reaction until the hydrogen storage alloy is charged to a predetermined capacity. Occurs. Therefore, at the end of charging, hydrogen gas is present inside the battery in addition to oxygen gas. Hydrogen gas, unlike oxygen gas,
Since it is not absorbed by the counter electrode, the amount of gas generated is directly linked to an increase in internal pressure. That is, when hydrogen gas is generated, the increase in internal pressure becomes large. The increase in the internal pressure shortens the battery life as described above.

Further, in order to manufacture an electrode using a hydrogen storage alloy, it is necessary to once form an alloy ingot into particles and form it into a required shape. In this forming step, the surface of the alloy particles is firm. An oxide film is easy to form. Since the initial capacity of the hydrogen storage electrode formed with the oxide film is considerably lower than the expected capacity, "activation" is required at the initial stage of charge / discharge. The activation means that the oxide film is destroyed to obtain a desired discharge capacity by performing charge / discharge for several cycles in the initial stage of charge / discharge.
In a battery using a hydrogen storage electrode having such characteristics, the electrode efficiency is naturally poor at the initial stage of charge / discharge, that is, the hydrogen gas storage / release efficiency is poor, and hydrogen gas accumulates inside the battery, causing internal pressure A rise occurs. The increase in the internal pressure shortens the battery life as described above.

As described above, the conventional nickel hydride battery has a problem that the battery life is shortened due to the increase in the internal pressure.

On the other hand, the hydrogen storage alloy is composed of a rare earth element that does not store hydrogen and a transition metal element that stores hydrogen, and is designed to easily store and release hydrogen. However, the rare earth element is likely to elute in the alkaline electrolyte and precipitate as a rare earth hydroxide on the surface of the hydrogen storage alloy. Since rare earth hydroxide has low conductivity,
It has reduced the activity of the hydrogen storage alloy and thus deteriorated the battery performance.

Further, since the surface of the hydrogen storage alloy is directly exposed to oxygen gas, an oxide film is formed on the surface of the hydrogen storage alloy, and the oxide film interferes with the hydrogen storage / release. , The electrode efficiency was poor.

As described above, the conventional nickel hydride battery has a problem that the battery performance is deteriorated due to the formation of the rare earth hydroxide or the oxide film.

[0010]

SUMMARY OF THE INVENTION The present invention is capable of suppressing an increase in internal pressure, and
Providing a nickel hydride battery that can suppress the formation of rare earth hydroxides and oxide films, thereby providing a long life and high performance, and a method of manufacturing such a nickel hydride battery with only simple steps The purpose is to provide.

[0011]

The nickel hydride battery of the present invention comprises a positive electrode using nickel hydroxide as a main active material and a hydrogen storage alloy containing at least one transition metal element as a main active material. In the nickel hydride battery composed of the negative electrode used, the separator, and the alkaline electrolyte, the hydrogen storage alloy particles contained a large proportion of the transition metal element in the surface portion thereof as compared with the inner portion. It is a rich layer, and the negative electrode contains the above-mentioned hydrogen storage alloy particles along with IIa group elements, IVa group elements, Va group elements, and VI
One or more elements arbitrarily selected from the group a element, the group VIII element, the group IIb element, In, Sn, and Sb are contained in the state of a simple substance or a compound.
Examples of the transition metal element contained in the hydrogen storage alloy include elements belonging to Group VIIa, Group VIII, and Group Ib of the periodic table.

The method for producing a nickel hydride battery of the present invention comprises: a positive electrode using nickel hydroxide as a main active material;
A hydrogen storage alloy containing one or more transition metals, a negative electrode using a main active material, a separator, a nickel hydride battery composed of an alkaline electrolyte, in a method for producing, hydrogen storage alloy particles, A first treatment step of removing the oxide film from the surface of the particles and subjecting the rare earth elements to elution from the surface portion of the particles, together with the hydrogen storage alloy particles, IIa group element, IVa group element of the periodic table, V
Group a elements, Group VIa elements, Group VIII elements, Group IIb elements, I
Second, one or more elements arbitrarily selected from n, Sn, and Sb are contained in the negative electrode in the state of a simple substance or a compound.
And a second processing step for performing processing.

[0013]

According to the nickel hydride battery of the first aspect, since the hydrogen storage alloy particles have the rich layer formed by removing the rare earth element, activation at the initial stage of charge and discharge is unnecessary. Moreover, the rich layer itself functions as a charge transfer reaction field. Therefore, the electrode reaction can be efficiently performed from the beginning of charge / discharge. Therefore, the problem that hydrogen gas is stored in the battery and the internal pressure of the battery rises due to the fact that hydrogen is not occluded and released in the early stage of charge and discharge is solved.

Further, since the negative electrode contains the above hydrogen-absorbing alloy and a simple substance or a compound of a predetermined element selected arbitrarily, the following action is achieved.

That is, the contained element is an IVa group element,
If it is any one of Va group element, VIa group element, VIII group element, In, Sn, and Sb, the element functions as a catalyst for reducing oxygen to hydroxide ion, so that the hydrogen storage electrode The consumption rate of oxygen gas in is improved. Therefore, the problem that the oxygen gas is stored in the battery and the internal pressure of the battery rises is solved. Further, these elements prevent the rare earth element from eluting from the hydrogen storage alloy particles into the alkaline electrolyte, and also prevent the surface of the hydrogen storage alloy from being oxidized. Therefore, the problem that the hydrogen storage electrode becomes inactive due to the adhesion of the rare earth hydroxide or oxide film on the surface of the hydrogen storage alloy particles is solved.

On the other hand, when the contained element is one of the IIa group element and the IIb group element, the element is
To shift the hydrogen generation potential of the hydrogen storage alloy to base,
The charging potential of the hydrogen storage electrode, that is, the potential difference from the hydrogen storage potential increases. Therefore, hydrogen generation, which is a side reaction during charging, is suppressed. Therefore, the problem that hydrogen gas is stored in the battery and the internal pressure of the battery rises is solved.
By the way, the hydrogen storage potential depends on the plateau pressure of the hydrogen storage alloy, and its equilibrium potential is expressed by the following equation (I). E _eq (H ₂ O / H) -E _eq = -0.9324-0.0291log P (H ₂ ) ... (I) As can be seen from the formula (I), hydrogen storage of a hydrogen storage alloy that is normally used. The potential does not increase dramatically based on the plateau pressure. Therefore, in order to increase the potential difference between the hydrogen storage potential and the hydrogen generation potential, it is necessary to shift the hydrogen generation potential to the base. The hydrogen evolution potential of a substance is
Since it depends on the hydrogen generation overvoltage of the surface substance, by coating the surface of the hydrogen storage alloy with a substance having a high hydrogen generation overvoltage, the hydrogen generation potential of the hydrogen storage alloy can be shifted to the base.

According to the method of manufacturing the nickel hydride battery of the second aspect, since both the first treatment step and the second treatment step are simple, the hydrogen storage electrode, and thus the nickel hydride battery, can be manufactured by a simple operation. Is obtained.

In the method for manufacturing a nickel hydride battery according to claim 3, when the hydrogen storage alloy particles are immersed in an aqueous solution having a pH of 2 to 6, the oxide film formed on the surface of the alloy is removed and the alloy is formed. Al, rare earth elements, etc. elute from the surface, and the surface portion of the alloy becomes a rich layer. When the acid is stronger than pH 2, N which is the main component of the alloy
Since i is eroded, the mass of the alloy is reduced and the electrode characteristics are deteriorated. Further, it becomes difficult to control the thickness of the rich layer, a thick rich layer is formed, and the composition of the rich layer changes abruptly from the composition of the internal portion, and the rich layer peels off as the cycle progresses. When the acid is weaker than pH 6, removal of the oxide film and elution of Al, rare earth elements, and the like are less likely to occur, and a rich layer is less likely to be formed. pH
Since the range of 2 to 6 includes the Al corrosion region,
Elution of Al easily occurs and a rich layer is easily formed.

In the method for manufacturing a nickel hydride battery according to claim 4, when the hydrogen storage alloy particles are immersed in an alkaline aqueous solution, the rare earth element is surely eluted from the surface of the alloy and the surface portion of the alloy becomes a rich layer. . Moreover, since the hydrogen storage alloy particles are once treated with alkali, further progress of corrosion due to the alkaline electrolyte after battery assembly is suppressed.

According to the method for manufacturing a nickel hydride battery of the fifth or sixth aspect, the reactivity is improved by the high temperature, the rich layer is easily formed, and the processing time is shortened.

According to the method for producing a nickel hydride battery of claim 7, it becomes easy to set the pH within the range of 2 to 6, and the fluctuation of the pH becomes small.

According to the method for manufacturing a nickel hydride battery of claim 8 or 9, the rare earth element is selectively eluted and the rich layer is easily formed.

According to the method for producing a nickel hydride battery according to any one of claims 10 to 13, in the negative electrode, the selected element is physically mixed with the hydrogen storage alloy particles or is attached to the surface of the hydrogen storage alloy particles. It will be included in the state.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. (Example 1) a hydrogen storage alloy was weighed with a composition of _{MmNi 3.8 Al 0.3 Co 0.7 Mn 0.2} , was placed in a crucible, the induction furnace is dissolved under an inert atmosphere to prepare a hydrogen-absorbing alloy ingot. The alloy ingot was crushed into particles having an appropriate particle size by mechanical crushing or hydrogenation crushing to obtain hydrogen storage alloy particles. Note that Mm is a misch metal, which is a composite of one or more rare earth elements of La, Ce, Pr, and Nd.

Next, the alloy particles were subjected to the first treatment. That is, the alloy particles were treated with acetic acid adjusted to 60 ° C. and pH 3.6.
It was immersed in a sodium acetate buffer solution, stirred, washed with water, and dried.

Regarding the alloy particles after the first treatment, X
Surface analysis by line photoelectron spectroscopy (XPS), high-magnification surface observation by transmission electron microscope (TEM), elemental analysis, and electron diffraction revealed that the alloy particles had the cross-sectional structure shown in FIG. It was That is, the rich layer 2 was formed on the surface portion of the alloy particles by the first treatment. 1 is the internal part or bulk. FIG. 2 shows the alloy composition ratio of the portion corresponding to FIG. Bulk 1 is MmNi
_3.8 A portion having the composition of Al _0.3 Co _0.7 Mn _0.2 , that is, the initial composition. The rich layer 2 had a thickness of 50 to 300 nm. The thickness of the rich layer 2 is controlled by the immersion time in the first treatment. As is clear from FIG. 2, in the rich layer 2, the content ratio of transition metal elements such as Ni, Co, and Mn is larger than that of the bulk 1 mainly due to the elution of Al and rare earth elements in Mm. ing.
Further, the pore size distribution of the alloy particles after the first treatment was measured. FIG. 3 shows the measurement result of the pore size distribution measured from the adsorption side. As is clear from FIG. 3, the surface of the alloy particles had a structure having many fine holes with a diameter of several tens of liters. Moreover, the surface area is about 400 m ² / g according to the measurement result of the specific surface area.
Was calculated and showed a considerably large value. Further, the alloy particles were visually diffusely reflected and exhibited a black color.

Next, the second treatment was performed. That is, 5 w of cobalt monoxide (CoO) powder was added to the alloy particles after the first treatment.
The mixture was mixed at t%, a thickener was further added to form a paste, and the paste was filled in a porous nickel metal substrate. Then, after drying, it was pressed to obtain a hydrogen storage electrode as a negative electrode. A 2 wt% aqueous solution of methyl cellulose was used as the thickener, and 27 wt% of this was added. A substrate having a porosity of about 95% was used.

On the other hand, a known paste type nickel electrode was prepared as a positive electrode. That is, 5 wt% of cobalt monoxide powder was mixed with nickel hydroxide powder, and a thickener was further added to form a paste, which was filled in a porous nickel metal substrate,
After drying, it was pressed to obtain a nickel electrode.

The thus obtained hydrogen storage electrode, nickel electrode, separator made of hydrophilic polypropylene, and K
A sealed AA size nickel hydride battery was produced using an electrolytic solution composed of an OH + LiOH aqueous solution.

CoO contained in the hydrogen storage electrode
It is considered that the powder is dissolved and deposited during charge / discharge, and adheres to the surface of the hydrogen storage alloy particles.

Example 2 Up to the first treatment, the same process as in Example 1 was performed. A nickel hydride battery was prepared in the same manner as in Example 1 except that chromium oxide (III) (Cr ₂ O ₃ ) powder was used in place of the cobalt monoxide powder in the second treatment.

(Embodiment 3) Up to the first treatment, the same process as in Embodiment 1 was performed. Next, a thickener was added to the alloy particles after the first treatment to form a paste, which was filled in a porous nickel metal substrate, dried, and pressed to obtain a hydrogen storage electrode. On the other hand, the same nickel electrode as in Example 1 was produced. Also, K
A small amount of tungstic acid (H ₂ WO ₄ ) powder was mixed into an electrolytic solution composed of an OH + LiOH aqueous solution. Next, a nickel hydride battery was produced using the hydrogen storage electrode, the nickel electrode, the separator, and the above electrolytic solution. Then, by leaving this battery at a constant temperature of 20 ° C. for 3 days, tungsten was deposited on the surface of the hydrogen storage electrode.

Example 4 In the second treatment, 1 w of titanium oxide (TiO ₂ ) powder was used instead of cobalt monoxide powder.
A nickel hydride battery was prepared in the same manner as in Example 1 except that the t% was mixed.

(Embodiment 5) In the second treatment, tantalum oxide (Ta ₂ O ₅ ) powder was used instead of cobalt monoxide powder.
A nickel hydride battery was prepared in the same manner as in Example 1 except that the wt% mixture was used.

Example 6 In the second treatment, calcium hydroxide (Ca (O) was used instead of the cobalt monoxide powder.
A nickel hydride battery was prepared in the same manner as in Example 1 except that H) ₂ ) powder was mixed in an amount of 1 wt%.

Example 7 In the second treatment, magnesium hydroxide (Mg (OH)) was used instead of the cobalt monoxide powder.
₂ ) A nickel hydride battery was prepared in the same manner as in Example 1 except that 1 wt% of the powder was mixed.

(Embodiment 8) In the second treatment, 3 wt% of antimony (Sb) powder was used instead of cobalt monoxide powder.
A nickel hydride battery was prepared in the same manner as in Example 1 except for mixing.

Example 9 In the second treatment, zinc oxide (ZnO) powder was mixed instead of the cobalt monoxide powder,
A nickel hydride battery was produced in the same manner as in Example 1 except for the above.

Comparative Example 1 A nickel hydride battery was manufactured in the same manner as in Example 1 except that the first treatment was not performed, the cobalt monoxide powder was not mixed in the second treatment.

(Comparative Example 2) The first treatment was performed in the same manner, and the cobalt monoxide powder was not mixed in the second treatment,
A nickel hydride battery was produced in the same manner as in Example 1 except for the above.

Comparative Example 3 A nickel hydride battery was produced in the same manner as in Example 4 except that the first treatment was not performed.

Comparative Example 4 A nickel hydride battery was produced in the same manner as in Example 5 except that the first treatment was not performed.

Comparative Example 5 A nickel hydride battery was produced in the same manner as in Example 6 except that the first treatment was not performed.

Comparative Example 6 A nickel hydride battery was produced in the same manner as in Example 7 except that the first treatment was not performed.

(Test 1) For each battery of Example 1 and Comparative Example 1, the voltage and the battery internal pressure at the time of 1.0 C × 200% charge were determined. FIG. 4 shows the result. As is clear from FIG. 4, in the battery of Example 1, the rise in battery internal pressure during overcharge was suppressed.

(Test 2) For each of the batteries of Example 2 and Comparative Example 2, the change in discharge utilization rate with the progress of charging / discharging was determined. The discharge utilization rate (%) is the value obtained by dividing the actual discharge capacity by the theoretical capacity when the theoretical capacity of the hydrogen storage alloy is 280 mAh per gram, and multiplied by 100. FIG. 5 shows the result. As is clear from FIG.
In the battery of Comparative Example 2, the capacity gradually decreased as the cycle was repeated. However, in the battery of Example 2,
It retains sufficient capacity even after many cycles. That is, the battery of Example 2 has excellent capacity characteristics.

(Test 3) For each of the batteries of Example 3 and Comparative Example 2, the change in discharge utilization rate was determined in the same manner as in Test 2.
FIG. 6 shows the result. As is apparent from FIG. 6, the capacity of the battery of Comparative Example 2 gradually decreased as the cycle was repeated, but the capacity of the battery of Example 3 was maintained even after the cycle was repeated many times. There is. That is, the battery of Example 3 has excellent capacity characteristics.

(Test 4) For each of the batteries of Examples 4, 5, 6, 7 and Comparative Examples 1, 3, 4, 5, 6, the initial change in discharge capacity was determined. The test condition is that after charging at a temperature of 20 ° C. for 15 hours with a current equivalent to 0.1 C of battery capacity,
It was decided to discharge the battery voltage to 1 V with a current equivalent to 0.2 C. FIG. 7 shows the result.

As is clear from FIG. 7, in the battery of Comparative Example 1, the discharge capacity in the first cycle was small, and the discharge capacity gradually increased as the cycle was repeated. Also,
The batteries of Comparative Examples 3, 4, 5, and 6 have smaller discharge capacities in the first cycle than the batteries of Comparative Example 1, and the increase in discharge capacity is small even if the cycle is repeated. By the way, the change of the discharge capacity in the initial stage of charge / discharge depends on the activation rate of the hydrogen storage electrode. Is a negative electrode capacity regulation. Comparative Examples 1, 3, 4,
In the batteries 5 and 6, since the rich layer is not formed,
Activation is slow. In the batteries of Comparative Examples 3, 4, 5, and 6, the coating film made of Ti, Ta, Ca, or Mg further covers the alloy surface at the time of injecting the electrolytic solution before the start of charge / discharge,
It is thought that activation is slow. On the other hand, in the batteries of Examples 4, 5, 6, and 7, Comparative Examples 1, 3, 4,
Since the discharge capacity is larger from the first cycle as compared with the batteries Nos. 5 and 6, the activation is considered to be faster. Since the rich layer is formed, a sufficient capacity can be obtained from the early stage of charge / discharge, and the coating film made of Ti, Ta, Ca, or Mg covers the alloy surface at the time of injecting the electrolytic solution before the cycle starts. However, it is considered that this did not adversely affect the activation of the alloy. That is, in the batteries of Examples 4, 5, 6 and 7, the electrode efficiency was good from the beginning of charge and discharge, that is, the occlusion and release of hydrogen gas was good, and the increase in internal pressure due to storage of hydrogen gas was suppressed. Therefore, the battery life is extended.

(Test 5) For each of the batteries of Examples 4, 5, 6, 7 and Comparative Examples 1, 3, 4, 5, 6, the change in discharge capacity and the change in battery internal pressure at the end of charging were determined. The test conditions were to charge at a temperature of 20 ° C. for 5 hours with a current equivalent to 0.3 C of the battery capacity, and then discharge with a current equivalent to 0.2 C until the battery voltage reached 1V. FIG. 8 shows the result.

As is apparent from FIG. 8, Examples 4, 5,
Compared with the batteries of Comparative Examples 1, 3, 4, 5, and 6, the batteries of Nos. 6 and 7 have significantly improved charge / discharge cycle characteristics including capacity characteristics and internal pressure characteristics. This is considered due to the following reasons. That is, in the battery of Comparative Example 1, acicular rare earth hydroxide was deposited on the surface of the negative electrode as the charge / discharge cycle proceeded,
Since the negative electrode capacity decreases, the battery capacity decreases and the battery internal pressure increases, whereas in the batteries of Examples 4, 5, 6, and 7, a film of Ti, Ta, Ca, or Mg is formed on the negative electrode surface. Therefore, it is considered that the precipitation of the rare earth hydroxide on the surface of the negative electrode is suppressed, the negative electrode capacity is maintained, and the decrease in battery capacity and the increase in battery internal pressure do not occur. In the batteries of Comparative Examples 3, 4, 5, and 6, Ti, T
Since the film of a, Ca, or Mg hinders activation of the alloy in the early stage of charge / discharge, the internal pressure of the battery rises,
It does not have good performance. That is, Examples 4, 5, 6, 7
The battery of (1) has a long life because the increase in internal pressure is suppressed, and the battery performance is also improved.

(Test 6) For each battery of Example 8 and Comparative Example 1, the voltage and the battery internal pressure at the time of 1.0 C × 150% charge were determined. 9 and 10 show the results. 9 relates to the battery of Example 8 and FIG. 10 relates to the battery of Comparative Example 1. As is clear from FIGS. 9 and 10, in the battery of Example 8, the oxygen partial pressure and the hydrogen partial pressure at the time of overcharge are suppressed, and the increase in the battery internal pressure is suppressed.

(Test 7) For each battery of Example 9 and Comparative Example 1, the voltage and the battery internal pressure at the time of 1.0 C × 150% charge were determined. FIG. 11 shows the result. As is clear from FIG. 11, in the battery of Example 9, the rise in battery internal pressure during overcharge is suppressed.

(Other Examples) (1) In each of the above examples, the first treatment is carried out using an acetic acid-sodium acetate buffer solution, but an alkaline aqueous solution having the same composition as the alkaline electrolyte used is used. You may do it. According to this, the rare earth element is surely eluted from the surface of the hydrogen storage alloy particles. Moreover, since the hydrogen storage alloy particles are once treated with alkali, further progress of corrosion due to the alkaline electrolyte after battery assembly is suppressed. And also by this, the obtained battery is
Similar to each of the examples, the effects of suppressing an increase in internal pressure and improving battery performance were achieved. Furthermore, in this case, when the temperature of the alkaline aqueous solution was set to 80 to 110 ° C., the reactivity was improved, the rich layer was easily generated, and the treatment time was shortened.

(2) The second process may be performed as follows. That is, a simple substance or compound of the selected element is applied in a powder state or a paste state to the surface of the negative electrode filled with the hydrogen storage alloy particles. According to this, the selected element is contained in a state of being physically mixed with the hydrogen storage alloy particles. Also by this, the obtained battery exhibited the effects of suppressing the increase in internal pressure and improving the battery performance, as in each of the examples.

By immersing the negative electrode filled with the hydrogen storage alloy particles in a solution containing a simple substance or a compound of the selected element, the element is attached to the surface of the negative electrode. According to this, the selected element is contained in a state of being attached to the surface of the hydrogen storage alloy particles. Also by this, the obtained battery exhibited the effects of suppressing the increase in internal pressure and improving the battery performance, as in each of the examples.

[0057]

According to the nickel hydride battery of claim 1, since the hydrogen storage alloy particles have a rich layer, the electrode reaction can be efficiently carried out from the beginning of charge and discharge, and the hydrogen gas is used as the battery. It is possible to suppress an increase in internal pressure of the battery due to the storage inside.

Further, since the negative electrode contains the above hydrogen-absorbing alloy and a simple substance or a compound of a predetermined element selected arbitrarily, the following effects can be obtained. That is, the contained elements are IVa group element, Va group element, VIa group element, VI
When it is one of the group II elements, In, Sn, and Sb, the oxygen gas consumption rate at the hydrogen storage electrode can be improved, and the increase in the internal pressure of the battery due to the storage of oxygen gas in the battery can be suppressed. it can. Further, it is possible to prevent the rare earth hydroxide or oxide film from adhering to the surface of the hydrogen storage alloy particles, and to prevent the hydrogen storage electrode from becoming inactive. On the other hand, when the contained element is one of the IIa group element and the IIb group element, hydrogen generation, which is a side reaction during charging, can be suppressed, and hydrogen gas is stored in the battery. An increase in internal pressure of the battery can be suppressed.

According to the method for producing a nickel hydride battery of the second aspect, the hydrogen storage electrode and eventually the nickel hydride battery can be obtained by a simple operation.

According to the method for manufacturing a nickel hydride battery of the third aspect, the rich layer can be satisfactorily obtained.

According to the manufacturing method of the nickel hydride battery of the fourth aspect, the rich layer can be satisfactorily obtained, and further the progress of corrosion due to the alkaline electrolyte after the battery is assembled can be suppressed.

According to the method for producing a nickel hydride battery of claim 5 or 6, the rich layer can be efficiently formed,
Processing time can be reduced.

According to the method for producing a nickel hydride battery of the seventh aspect, the pH can be easily set within the range of 2 to 6, and the fluctuation of the pH can be reduced.

According to the method for producing a nickel hydride battery of claim 8 or 9, the rare earth element can be selectively eluted and the rich layer can be satisfactorily obtained.

According to the method for manufacturing a nickel hydride battery of the tenth to thirteenth aspects, the selected element can be favorably contained in the negative electrode.

[Brief description of drawings]

FIG. 1 is a partial sectional view of a hydrogen storage alloy after a first treatment of Example 1.

FIG. 2 is a diagram showing an alloy composition ratio of a portion corresponding to FIG.

FIG. 3 is a diagram showing a pore size distribution of the hydrogen storage alloy after the first treatment of Example 1.

FIG. 4 is a diagram showing the results of test 1.

FIG. 5 is a diagram showing the results of test 2.

FIG. 6 is a diagram showing the results of test 3.

FIG. 7 is a diagram showing the results of test 4.

FIG. 8 is a diagram showing the results of test 5.

FIG. 9 is a diagram showing the results of test 6.

FIG. 10 is a diagram showing the results of test 6.

FIG. 11 is a diagram showing the results of test 7.

[Explanation of symbols]

 1 Rich layer 2 Bulk

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takehito Bokeuchi 6-6 Josaimachi, Takatsuki City, Osaka Prefecture Yuasa Corporation (72) Inventor Kengo Furukawa 6-6 Josaimachi, Takatsuki City, Osaka Stocks Company Yuasa Corporation (72) Inventor Yuichi Matsumura 6-6 Josaimachi, Takatsuki City, Osaka Prefecture Yuasa Corporation Co., Ltd. (72) Inventor Masahiko Oshiya 6-6 Josaimachi, Takatsuki City, Osaka Yuasa Corporation Within

Claims (13)

[Claims] 1. A positive electrode using nickel hydroxide as a main active material, a negative electrode using a hydrogen storage alloy containing at least one transition metal element as a main active material, a separator, and an alkaline electrolyte. In the configured nickel hydride battery, the hydrogen storage alloy particles have a surface layer that is a rich layer containing a larger proportion of the above transition metal element than the internal portion, and the hydrogen storage alloy particle has IIa of the periodic table together with the occlusion alloy particles
It contains a single substance or a compound of one or more elements arbitrarily selected from Group Group elements, IVa group elements, Va group elements, VIa group elements, VIII group elements, IIb group elements, In, Sn, and Sb. A nickel hydride battery characterized by the above. 2. A positive electrode using nickel hydroxide as a main active material, a negative electrode using a hydrogen storage alloy containing at least one transition metal as a main active material, a separator, and an alkaline electrolyte. And a first treatment step of subjecting the hydrogen storage alloy particles to a first treatment for removing the oxide film from the particle surfaces and eluting rare earth elements from the surface portions of the particles. , Together with the above hydrogen storage alloy particles, IIa group element of the periodic table, IV
1 arbitrarily selected from a group element, Va group element, VIa group element, VIII group element, IIb group element, In, Sn, and Sb
A method for producing a nickel hydride battery, comprising: a second treatment step of performing a second treatment in which a single substance or a compound of one or more elements is contained in the negative electrode. 3. The first treatment is to adjust the pH of the hydrogen storage alloy particles to pH.
The method for manufacturing a nickel hydride battery according to claim 2, wherein the nickel hydride battery is immersed in the aqueous solution of 2 to 6 and then washed with water and dried. 4. The nickel hydride battery according to claim 2, wherein the first treatment is to immerse the hydrogen storage alloy particles in an aqueous alkaline solution having the same composition as the alkaline electrolyte used, followed by washing with water and drying. Manufacturing method. 5. The method for producing a nickel hydride battery according to claim 3, wherein the aqueous solution is set at 20 to 90 ° C. 6. The method for producing a nickel hydride battery according to claim 4, wherein the aqueous solution is set at 80 to 110 ° C. 7. The method for producing a nickel hydride battery according to claim 3, wherein the aqueous solution is an acetic acid-acetate buffer solution. 8. The aqueous solution is an aqueous solution of an organic acid.
A method for producing the nickel hydride battery described. 9. The organic acid is formic acid, acetic acid, propionic acid,
9. The method for producing a nickel hydride battery according to claim 8, which is arbitrarily selected from butyric acid, malonic acid, oxalic acid, acrylic acid, valeric acid, glycolic acid, citric acid, succinic acid, glutaric acid, lactic acid and tartaric acid. . 10. The second treatment is a step of directly mixing the hydrogen storage alloy particles with a simple substance or a compound of the selected element, and then filling the negative electrode current collector in the form of paste.
A method for producing the nickel hydride battery described. 11. The second treatment is to form a battery using an anode prepared by filling an electrolyte containing a simple substance or a compound of a selected element and hydrogen storage alloy particles, and then depositing the element on the surface of the anode. The method for manufacturing a nickel hydride battery according to claim 2, wherein 12. The nickel according to claim 2, wherein the second treatment is to coat the surface of the negative electrode filled with hydrogen storage alloy particles with a simple substance or a compound of the selected element in a powder state or a paste state. Manufacturing method of hydride battery. 13. The second treatment is to deposit the element on the surface of the negative electrode by immersing the negative electrode filled with hydrogen storage alloy particles in a solution containing a simple substance or a compound of the selected element. Item 3. A method for manufacturing a nickel hydride battery according to Item 2.