JPH05343062A - Hydrogen storage alloy battery - Google Patents

Abstract

PURPOSE:To manufacture a hydrogen storage alloy battery having an excellent discharge characteristic by containing two or more phase contained particles in hydrogen storage alloy particles by a specific ratio in a negative electrode of the hydrogen storage alloy battery formed by integrating hydrogen storage alloy powder into a metallic porous body. CONSTITUTION:A hydrogen storage alloy battery is composed of a negative electrode formed by integrating hydrogen storage alloy powder (Ti-Ni type) into a metallic porous body wire gauze, expanded metal and so on), a positive electrode, a separator and electrolyte. At this time, two or more phase contained particles (Zr, V and so on) are contained in hydrogen storage alloy particles of the negative electrode by not less than 50 volume %. Thereby, since a hydrogen storage and release capacity can be heightened, the hydrogen storage alloy battery having high charge and discharge efficiency can be provided.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a hydrogen storage alloy battery using a hydrogen storage alloy as a negative electrode active material.

[0002]

2. Description of the Related Art Conventionally, nickel-cadmium batteries have been widely used as alkaline secondary batteries, but since cadmium has an adverse effect on the environment, recently, Ti-Ni, which can be expected to have a higher capacity as a substitute, has been developed. Attention has been paid to a hydrogen storage alloy battery using a hydrogen storage alloy as a negative electrode active material.

[0003]

However, the above battery does not have satisfactory characteristics in terms of discharge capacity and cycle life.

Therefore, an object of the present invention is to provide a hydrogen storage alloy battery having good discharge characteristics.

[0005]

[Means for Solving the Problems] A hydrogen storage alloy battery comprises a hydrogen storage alloy powder integrated with a metal porous body such as a wire mesh or expanded metal, compression molded, and sintered to form a sheet-shaped negative electrode. On the other hand, nickel hydroxide powder is made into a paste together with a conductive auxiliary agent, a binder, etc., and filled into a sheet of porous metal, which is then dried, aged, and thickened to form a positive electrode, and a current collector terminal is attached to the positive electrode. , Both of which are spirally wound through a separator made of a synthetic fiber non-woven fabric to form a spirally wound electrode body, which is housed in a battery case, injected with an electrolytic solution, sealed, and then activated and chemically treated. And complete as a battery.

The hydrogen storage alloy battery of the present invention will be described in detail below in the order of negative electrode preparation, positive electrode preparation, separator, electrolytic solution, and battery assembly.

1. Preparation of Negative Electrode As a hydrogen storage alloy used as a negative electrode active material, Ti-
A Ni-based hydrogen storage alloy is suitable because it has a large capacity.

[0008] This Ti-Ni system hydrogen storage alloy makes it easy to prepare a multiphase system alloy, and the existing form of the phase can be controlled quite freely depending on the composition. Usually, it is said that activation of a Ti-Ni-based hydrogen storage alloy is not easy, but it can be solved by controlling the state of such a phase.

Even in such a Ti--Ni type hydrogen storage alloy, in order to facilitate control of the phase state, Ni is used.
(Nickel) is at least 1.5 times the amount of Ti (titanium)
It is preferable to mix them in a large amount more than twice, or to add a third or more metal component. In addition, in this specification, the amount ratio of the components of the hydrogen storage alloy is based on the atomic ratio.

Examples of such third or more metal components include Zr (zirconium), V (vanadium), Cr (chromium), Fe (iron), Mn (manganese), Co (cobalt), Al ( Aluminum) and the like are preferable, and Zr and V are particularly preferable. Although these metal components may be added individually, they are more effective when used in combination.

When Zr and V are added to the Ti-Ni alloy, it is preferable that Zr be larger than V. Also Zr
When Cr and Cr are added, it is preferable to add Zr twice or more of Cr.

Further, when Zr and Fe, Co, Cr, etc. are added, it is preferable to add Fe, Co, Cr in the range of half or less of Zr, respectively.

Although Mn can be added at the same time, it is better to control the amount to be Zr or less. When Fe, Co, Cr and the like are used together, Mn is preferably larger than these metals.

As a practical alloy composition, at least Ti-Ni-V, Ti-Ni-Zr, Ti-N is used.
i-Cr, Ti-Ni-Fe, Ti-Ni-Mn, Ti
-Ni-Co, Ti-Ni-V-Cr, Ti-Ni-V
-Fe, Ti-Ni-V-Mn, Ti-Ni-VC
o, Ti-Ni-Zr-Cr, Ti-Ni-Zr-F
e, Ti-Ni-Zr-Mn, Ti-Ni-Zr-Co
Alloys containing as an element are mentioned.

In order to make the alloy phase three or more polyphases, it is preferable to make the composition of at least three elements, preferably four elements, five elements or more multielements based on the above main composition. ..

In alloying, when selecting the above elements, the discharge capacity, the characteristics at low temperature, the characteristics at high temperature, the number of charge / discharge cycles, the suppression of battery internal pressure, the workability of the negative electrode, the durability, and the PCT curve are preferable. Pattern, ease of current collection, moderate negative electrode surface area, rapid charging characteristics, preferable particle size of alloy particles, suppression of invasion of nitrogen or carbon, rolling characteristics to give desired packing density, hydrogen content as discharge reserve It is recommended to select the most preferable combination according to various purposes such as expansion of the permissible amount, control of the existence ratio of the second phase or less, control of the sintering progress rate, and the like.

In any case, by mixing such elements, at least three different phases as an alloy can appear.

By using multiple phases as described above, the discharge characteristics can be improved. That is, when the hydrogen storage alloy particles in the negative electrode are composed of such a multiphase alloy in an amount of 50% by volume or more, very excellent characteristics are exhibited, and the effect is particularly remarkable when three or more phases are present.

The proportion of the second and lower phases is preferably 10 to 40% by volume in the multiphase alloy portion. At this time, the hydrogen storage alloy has a particle size of 10 to 75 μm.
By using one of these, a negative electrode having good characteristics can be constructed.

A trace amount of carbon and nitrogen impurities in the hydrogen storage alloy may lead to the production of methane and nitrogen gas in the battery, which may cause an increase in internal pressure and impair the long-term reliability of the battery. Even if it is the most, it is preferable to limit it to 0.02% by weight or less in the alloy.

In particular, in the case of a Ti--Ni type hydrogen storage alloy, when a carbon crucible is used in the melting process, a large amount of carbon will invade, so the selection of the melting method is important. It is desirable to use equipment designed to reduce arc melting or carbon contamination.

Since nitrogen enters from the air in the step of pulverizing the hydrogen storage alloy, it is preferable to pulverize in a nitrogen-free atmosphere.

The hydrogen storage alloy powder preferably has a BET surface area of 2 m ² / g or more, particularly 3 to 5 m ² / g. By using such a hydrogen storage alloy having a large surface area, a highly reactive negative electrode can be obtained, and a battery having a large discharge capacity can be obtained.

The hydrogen-absorbing alloy powder thus produced is composed of wire mesh, expanded metal, punching metal,
It is integrated with a metal porous body such as a metal fiber.

The metal porous body has a base material thickness of 0.12.
~ 0.17mm, mesh size SW 1.1 ~ 1.5m
m, LW is 1.5 to 2.5 mm, basis weight is 0.03 to 0.0
A nickel expanded metal of 5 g / cm ² is particularly preferably used.

In the sheet-shaped negative electrode thus integrated, roll rolling is performed so that the packing density of the hydrogen storage alloy (portion excluding the metal porous body) is 5.2 to 5.7 g / cm ³ . Is preferred.

With such a packing density, a battery having favorable characteristics in which the load characteristics of the battery and the internal pressure during charging are appropriately balanced can be obtained.

At this time, the porosity excluding the current collector of the negative electrode is 1
It is 5 to 26% by volume, and the distribution of pores is 1 to 20 μm and is 40% or more.

After rolling the negative electrode, the negative electrode was placed in an atmosphere of an inert gas such as argon containing hydrogen in an amount of about 5% by volume or less.
It is heated to 00 ° C. or higher for sintering, cooled to near room temperature, and then taken out from the sintering furnace.

When a small amount of hydrogen of about 5% by volume or less is contained in the inert gas atmosphere during sintering, the surface of the negative electrode is prevented from being oxidized by a very small amount of oxygen in the sintering furnace, and the discharge reserve is provided. Hydrogen may be included in the negative electrode in advance. As a result, hydrogen corresponding to the PCT characteristics is contained in the negative electrode at the end of sintering.

The negative electrode thus obtained has a thickness of 0.
2 to 0.4 mm sheet, 0.07 to 0.2 g / c
Those having a filling amount of m ² are desirable.

2. Production of Positive Electrode The positive electrode to be combined with the negative electrode produced as described above is preferably one produced as described below.

That is, a nickel porous sheet is used as a substrate, and nickel hydroxide powder as an active material, a conductive auxiliary agent, a binder, a thickener and water are mixed to form a paste. It is finished as a positive electrode through the step of filling the voids.

From the viewpoint of increasing the discharge capacity, it is desired that the substrate retain as much nickel hydroxide powder as possible.

Therefore, the substrate has a porosity of 90 to 98.
It is preferable to use a volume% fibrous porous nickel sheet.

Such a fibrous nickel porous material sheet is produced by a method in which the surface of a chemical fiber nonwoven fabric is nickel-plated, and the chemical fibers inside are thermally decomposed and removed in a reducing atmosphere. The obtained product has a high porosity of 90% by volume or more and a packing density of 550 mAh /
It is preferable because it increases to cc or more.

In order to improve the packing density of the nickel hydroxide powder in such a fibrous nickel porous body sheet, it is preferable to use a chemical fiber nonwoven fabric having a low fiber density as a raw material for the porous body sheet. It is conceivable that in this case, the relative distance between the nickel hydroxide powder held between the nickel fibers of the substrate and the substrate becomes large, which may lead to a decrease in the active material utilization rate during charge / discharge, and thus requires caution. ..

The nickel hydroxide powder as the active material preferably has an average particle size of 3 to 25 μm. In the pore distribution curve of nickel hydroxide, the main peaks near 6Å and 5, 8, 10
Although a sub-peak near Å appears, empirically, if the height ratio of sub-peak / main peak is 0.05 or more, the packing density becomes high and the battery has excellent load characteristics.

Further, when zinc is contained in the particles of nickel hydroxide powder in an amount of 0.5 to 10% by weight, swelling of the positive electrode due to charge and discharge cycles is suppressed and charging efficiency at high temperatures is improved, resulting in good characteristics. Batteries can be obtained.

When cobalt is further contained in the particles of the nickel hydroxide powder, the amount of zinc added is preferably 0.05 to 30 times.

The nickel hydroxide powder itself as the active material is
Since it is inferior in conductivity, it is preferable to add metal nickel powder separately as a conduction aid. As the metallic nickel powder, one having an average particle diameter of 0.5 to 3 μm is suitable.

This metallic nickel powder assists the conduction between the nickel hydroxide powder and the nickel fibers of the fibrous nickel porous body sheet of the substrate.

Furthermore, it is preferable to use a metal powder other than nickel as a sub-conductivity aid. This is because metallic nickel changes into nickel hydroxide as the charge / discharge cycle continues, and the electrical conductivity decreases, so that the metallic nickel does not serve as a conductive additive. Therefore, it is, of course, necessary that the auxiliary conduction aid does not have such a concern.

As such an auxiliary conduction aid, for example, cobalt powder or the like can be used, and in terms of size, those having an average particle diameter of 0.5 to 3 μm are preferable.

It is preferable to add 5 to 20 parts by weight of these conductive auxiliary agent powders to 100 parts by weight of nickel hydroxide. When nickel powder and metal powder other than nickel such as cobalt are used in combination, The atomic ratio of (nickel powder / metal powder other than nickel such as cobalt) is preferably in the range of 3 or less.

That is, when the atomic ratio is 3 or less, the utilization factor of the active material is further improved and the discharge capacity density is increased.

The conductive auxiliary agent powder and the nickel hydroxide powder are
It is preferable to dry-mix in advance and then add a sodium salt of carboxymethyl cellulose (CMC) aqueous solution and polytetrafluoroethylene (PTFE) dispersion to form a positive electrode active material paste.

By doing so, the dispersibility is improved as compared with the case where the above powder is directly added and mixed in the aqueous solution of the sodium salt of carboxymethyl cellulose, and a higher utilization rate than before can be obtained.

The polytetrafluoroethylene used is preferably fibrillated. Such fibrillation of polytetrafluoroethylene can be achieved by thoroughly mixing the positive electrode active material paste.

When fibrillated polytetrafluoroethylene is used, the thickness when used as a positive electrode is 0.9 mm.
Even if the thickness is as thin as the following, even when the positive electrode is wound with a curvature of about 1.5 mm or less, there is an advantage that the positive electrode active material can be prevented from falling off.

As the positive electrode, a fibrous porous nickel sheet was filled with a positive electrode active material paste containing not only nickel powder as a main conductive auxiliary agent but also metallic cobalt powder as a secondary conductive auxiliary agent by impregnation or coating. After that, by performing a process of heating after immersion in an alkali, achievement of improvement in utilization rate and swelling of the positive electrode due to charge / discharge cycles can be prevented.
It is possible to keep it below 5%.

In the heating step after immersion in alkali, since the metallic cobalt is once dissolved and the surface of all the positive electrode constituents is covered with the dissolved material, cobalt oxyhydroxide having relatively excellent conductivity is charged on the positive electrode surface by charging and discharging. Can be formed. As a result, the discharge capacity density of the battery increases.

As the alkali aqueous solution for dipping in alkali, for example, potassium hydroxide aqueous solution, sodium hydroxide aqueous solution, lithium hydroxide aqueous solution and the like are suitable, and the alkali concentration thereof is preferably about 5 to 40% by weight.

The heating temperature is preferably 40 to 100 ° C. The reaction for 0.1 hour or more is effective for forming the cobalt oxyhydroxide film, and 20 hours or less is sufficient for growing the film.

By doing so, 50% by weight or more of the metallic cobalt added to the paste is changed to cobalt oxide or cobalt hydroxide before the battery is assembled, and the conductive film of the cobalt compound is sufficiently formed. That is, the utilization rate at the time of discharge can be improved.

The paste-type positive electrode after the above treatment has a color tone of brown to black and a specific resistance in the thickness direction of 25 Ω.
cm or less (at the time of applying a pressure of 1 kg / cm ² : SUS plates having a diameter of 37 mm are pressed against both surfaces of the positive electrode and the resistance therebetween is measured by an ohmmeter), and an aqueous potassium hydroxide solution having a concentration of 30% by weight (however, 17 g The equilibrium potential is 0 V or more with respect to the mercury / mercuric oxide reference electrode when immersed in 1 / l of lithium hydroxide).

The battery using the above-mentioned paste type positive electrode has a high utilization rate of 90% or more of the filling capacity from the first charging / discharging, and the discharge capacity after chemical conversion treatment is 110 AA batteries.
It becomes as large as 0 mAh or more.

A portion without an active material provided in a portion approximately 20 mm from one end of the long side of the sheet-shaped positive electrode thus produced (the portion without the active material has a width of 4 mm and is approximately 0. A nickel ribbon having a thickness of 0.1 mm, a width of 3 mm and a length of 50 mm is attached as a current collecting terminal to (previously compressed to a thickness of 2 mm).

Various methods can be adopted for attaching the current collector terminal, but welding, particularly spot welding is preferable, and the value obtained by dividing the welding diameter at the spot welding by the positive electrode area is 0.000.
Good terminal connection can be achieved when the total area of the spot portion is 15 to 0.00063 / mm and is 0.4 mm ² or more.

When such conditions are selected, the welding strength of the positive electrode is sufficient, the positional accuracy during spot welding is easily controlled, the total welding area is sufficiently obtained, and the electric resistance is reduced (1 kHz). The impedance of the battery during measurement can be suppressed to 40 mΩ or less in the case of AA battery), and good discharge characteristics can be obtained.

Further, spot welding is preferably started from a position where the upper end is closer to the upper end within 5% of the positive electrode height from the positive electrode upper end. This is because bending is performed when the current collecting terminal is connected to the sealing plate of the sealing lid at the time of battery assembly, but it is suitable for preventing a short circuit at that time.

3. Separator A non-woven fabric made of synthetic fiber such as polyamide or polypropylene is preferably used as the separator.

This is because the eluate from the separator into the electrolytic solution has a great influence on the self-discharge characteristics and the like, so that it is preferable to use a material having a small amount of such eluate into the electrolytic solution. is there.

In particular, when a nitrogen compound is eluted, self-discharge tends to occur, and therefore it is necessary to use a nitrogen compound that is less eluted. From this point, the concentration is 30% by weight.
Aqueous potassium hydroxide solution (however,
After the separator (area = 1075 cm ² ) was stored in 100 ml of an electrolytic solution consisting of 7 g / l) at 45 ° C for 3 days, the electrolytic solution showed substantially no Nessler reaction, or mercury / mercuric oxide. When cyclic voltammetry is performed using platinum electrodes as the reference electrode for both the working electrode and the counter electrode, good cell characteristics are exhibited when the oxidation peak near -0.3 V is below a certain value as shown below.

The conditions of the above cyclic voltammetry are as follows. With a scan speed of 10 mV / sec,
Scanning from −0.95V to + 0.65V was repeated three times, and after holding at −0.95V for 30 minutes, the next −
The oxidation peak near 0.3 V is 100 μA / cm ² or less,
It is preferably 20 μA / cm ² or less. The total amount of nitrogen in the separator is preferably 500 ppm or less, more preferably 200 ppm or less.

4. Electrolyte Solution An aqueous solution of potassium hydroxide or sodium hydroxide is preferably used as the electrolyte solution. The concentration of potassium hydroxide or sodium hydroxide in the electrolytic solution is 25 to 35% by weight.
Is preferred.

At this time, potassium hydroxide and sodium hydroxide may be used alone or as a mixture of both.

Lithium hydroxide was added to the electrolyte solution 1
When 20 g or less is added to the liter, the charge and discharge characteristics of the positive electrode are improved.

5. Assembly of Battery The positive electrode and the negative electrode obtained as described above are spirally wound via a separator so that the outermost periphery becomes the negative electrode, and the spirally wound electrode body is formed and then inserted into the battery case. Next, after injecting the electrolytic solution, the opening of the battery case is sealed with the sealing lid, thereby completing the battery assembly.

How to determine the dimensions of the positive electrode and the negative electrode depends not only on the shape design but also on the performance of the battery directly as a matter of the filling amount of the positive electrode and the negative electrode.

That is, the size of each sheet of the positive electrode and the negative electrode is determined as the filling amount of each when actually manufacturing the battery.

The filling amount is determined so that the equilibrium hydrogen pressure at 60 ° C. becomes 5 atm or less when the negative electrode in the portion facing the positive electrode is fully charged when the filling amount of the positive electrode active material is 100%. To be done. This is to prevent the internal pressure from unnecessarily rising and the reliability such as the battery life from being deteriorated when performing rapid charging of about 1 CA.

Further, if the entire surface of the positive electrode faces the negative electrode having a predetermined thickness during winding, the internal pressure can be suppressed to be low. The thickness ratio of the positive electrode / negative electrode is preferably 1 to 2.

When the thickness of one surface of the positive electrode faces the negative electrode and the back surface of the negative electrode facing the positive electrode faces the positive electrode, the negative electrode in that portion is charged deeper than a predetermined amount, and the internal pressure increases remarkably. Be careful because it may happen.

The discharge reserve can also be secured by adjusting the irreversible rate at the time of initial charging of the positive electrode.

After the battery is assembled, it is generally stabilized by performing activation treatment and chemical conversion treatment. The activation process is T
In the case of a battery using an i-Ni-based hydrogen storage alloy as a negative electrode active material, the battery is usually stored at 45 to 80 ° C for 12 to 120 hours.

By undergoing such an activation treatment,
The battery has a negative electrode surface area of about 1.5 when measured by the BET method.
Since it becomes m ² / g or more, the overall characteristics of the battery can be secured.

The chemical conversion treatment is performed by repeating charging and discharging several times. Especially when the battery is charged for the first and second times, the battery capacity is 2
If overcharging is performed up to about 5 times, a predetermined capacity can be obtained early. Further, it is also effective to leave the electrolyte solution stable by leaving it at 0 to 40 ° C. for 2 days or more before storage at high temperature.

In addition to the above, after the normal discharge at the time of the chemical conversion treatment, a process of applying a voltage of -0.2 V to +0.5 V between the terminals of the battery for about 1 hour is performed, or a force of -0.2 V is applied.
By combining the treatment of discharging with a constant current of about 0.01 CA up to the vicinity of V, the low temperature characteristics are further improved. This is probably because the oxide layer on the surface of the negative electrode was removed by the treatment.

During the chemical conversion treatment, the positive electrode in the wound state swells by 5 to 10% particularly in the thickness direction, and in the subsequent charge and discharge, the total swelling is 25% compared to that before the charge and discharge.
Less than the following.

The outer diameter of the spirally wound electrode body (positive electrode + negative electrode + separator) after winding is formed smaller than the inner diameter of the battery case so that it can be easily inserted into the battery case. It expands due to injection and conversion treatment by charging and discharging as described above, and the negative electrode at the outermost periphery and the inner wall of the battery case are about 2 k
Since contact is made with a pressure of g / cm ² to enhance the current collecting effect, not only discharge by high current becomes possible but also electrode active material can be prevented from falling off.

[0082]

Example A negative electrode was prepared as follows.

As a hydrogen storage alloy, Ti is 1 in atomic ratio.
5 parts, Zr 21 parts, V 15 parts, Ni 32 parts, Cr
5 parts, Fe 4 parts, Co 5 parts, Mn 3 parts,
An alloy was prepared by mixing and arc melting. As a result of microscopic observation, five different phases were found in this alloy.

First, the storage and desorption of hydrogen was repeated twice in the ingot of the obtained alloy, and then mechanically crushed by a ball mill. The powder after pulverization was classified to have a particle size of 10 to 75 μm (average particle size of 45 μm). All operations were performed in an argon atmosphere.

Ti ₁₅ Zr ₂₁ V obtained as described above
Hydrogen storage alloy powder having a composition of ₁₅ Ni ₃₂ Cr ₅ Fe ₄ Co ₅ Mn ₃ and base material thickness 0.15 mm, mesh size SW
1.3 mm, LW 2.0 mm, basis weight 0.037 g / cm
The nickel expanded metal of ² was simultaneously supplied and compressed by a roll mill to be integrated to obtain a sheet-shaped negative electrode. At this time, the thickness of the negative electrode was 0.30 mm, and the packing density of the hydrogen storage alloy was 5.5 g / cm ³ .

Next, the above sheet-shaped negative electrode was placed in a sintering furnace, and a mixed gas of argon / hydrogen = 99/1 was flowed in an amount of 1/10 in the sintering furnace for 1 minute to replace it at room temperature. The temperature was raised to 900 ° C. in 1 hour and sintered at 900 ° C. for 15 minutes. After sintering, the temperature was lowered to 30 ° C., and then the negative electrode was taken out of the sintering furnace.

The atmosphere at the time of sintering is 20 ppm oxygen concentration.
The humidity was −55 ° C. in terms of dew point. The density of the negative electrode after sintering was the same as that before sintering, and there was no change at all.

After the completion of sintering, the amounts of carbon and nitrogen were confirmed. As a result, the alloy components contained 0.011% by weight of carbon and 0.015% by weight of nitrogen.

The amount of discharge reserve after sintering is 0.01% by weight.
Met. This sheet-shaped negative electrode is 41 mm x 111 mm
It was cut into (thickness 0.3 mm) and put into a state for use in battery assembly.

On the other hand, the positive electrode was manufactured by the following method.

As the fibrous porous nickel sheet serving as a substrate, Fiber (trade name) manufactured by Katayama Special Industrial Co., Ltd. was used. This fibrous porous nickel sheet had a thickness of 1.6 mm and a porosity of 96% by volume.

As the nickel hydroxide powder, zinc 1.9
Particles in which 5% by weight of cobalt and 5% by weight of cobalt are simultaneously dissolved,
The main peak around 6Å and 5, 8, 1 in the pore distribution curve
The height ratio of the "sub-peak / main peak" to the sub-peak near 0 was 0.2.

As the conductive auxiliary agent, nickel (Ni) powder type 255 (average particle diameter 2.2 μm) manufactured by Inco Co., Ltd.
And cobalt (Co) fine powder manufactured by MHO Co. (average particle size 1.5 μm) was used.

To 100 parts by weight of the nickel hydroxide, 11.6 parts by weight of the nickel powder and 4.4 parts by weight of the cobalt powder were added and mixed by a dry method for 1 hour.

To this mixture, 50 parts by weight of a sodium salt aqueous solution of carboxymethyl cellulose having a concentration of 2% by weight and 5 parts by weight of polytetrafluoroethylene dispersion [Polyflon D-1 (trade name) manufactured by Daikin Industries, Ltd.] Parts were added and mixed to obtain an active material paste.

The obtained active material paste was put into a beaker, and a fibrous nickel porous sheet of 50 mm × 100 mm was prepared in the active material paste (provided that a compressed portion having a width of 4 mm was provided in the short side direction in the vicinity of the center in advance. The parts were soaked with taping that they were not filled with the active material), the whole of them was placed in a desiccator, and the pressure was reduced to normal pressure. As a result, the active material paste was filled in the fibrous nickel porous body sheet.

After the fibrous nickel porous body sheet was filled with the active material paste, it was heated and dried at 85 ° C. for 1 hour. Then, it was pressed to a thickness of 0.7 mm and immersed in an alkaline aqueous solution (aqueous potassium hydroxide solution having a concentration of 30% by weight) at 80 ° C. for 30 minutes. After the immersion, it was thoroughly washed with water, and again heated and dried at 85 ° C. for 1 hour to obtain a sheet-shaped positive electrode.

The color tone of the obtained positive electrode was dark brown, and the equilibrium potential in the electrolytic solution was 50 mV with respect to the mercury / mercuric oxide reference electrode. The residual amount of metallic cobalt was 30%, and the specific resistance in the thickness direction was 24 Ω · cm.

The sheet-shaped positive electrode is 39 mm × 82 mm
3mm in width and 51mm in length as a collector terminal and lead body in the part where the taping was removed by cutting to (0.7mm thickness)
The nickel ribbon of No. 3 was spot-welded to be ready for battery assembly.

The spot welding described above was performed from the upper end of the positive electrode to 0.
Starting from the part separated by 5 mm, the test was carried out at 5 places with a diameter of 1 mm. The total area of the spot portion was 3.9 mm ² . The filling capacity (theoretical capacity) of this positive electrode was 1150 mAh.

As the separator, a grafted polypropylene non-woven fabric (No. 700 manufactured by Cymat Co., thickness 0.1
3 mm), which was cut into a length of 250 mm and a width of 43 mm and bent at the center for use.

After this separator was immersed in an electrolytic solution at 45 ° C. for 3 days, the cyclic voltammetry of the electrolytic solution was measured under the above-mentioned conditions. The peak near −0.3 V was only 15 μA / cm ² Met. Also,
The total nitrogen content in the separator was 100 ppm.

The positive electrode and the negative electrode produced as described above were spirally wound through a separator as shown below to obtain a spiral electrode body.

A pair of semi-cylindrical rods obtained by cutting a steel rod having a diameter of 3.5 mm at the center was used as a winding core. A separator that was folded in two was sandwiched between the winding cores, and the separator was rotated once around the winding core. Wrap, then sandwich the negative electrode between the separators 1
I wrapped it around. After that, the positive electrode was placed with a separator interposed therebetween and completely wound. The number of windings was about 3.5. The obtained spiral electrode body had an outer diameter of 13.2 mm and the negative electrode was exposed at the outermost periphery.

This spiral electrode body was inserted into a battery case having an inner diameter of 13.4 mm in which nickel was plated on iron, and the concentration was adjusted to 3
2 ml of a 0 wt% potassium hydroxide aqueous solution (however, lithium hydroxide was dissolved in 17 g / l) was injected, and the opening of the battery case was sealed with a sealing lid.

The obtained battery was stored at 70 ° C. for 24 hours, activated, and then charged at 0.2 A for 15 hours to give 0.2
The chemical conversion treatment was carried out by repeating charging and discharging, in which A was discharged to 0.9 V, twice. The structure of the battery thus obtained is shown in FIG.

In FIG. 1, 1 is a positive electrode, 2 is a negative electrode, 3 is a separator, 4 is a spiral electrode body, 5 is a battery case, 6 is an annular gasket, 7 is a sealing lid, 8 is a terminal plate, 9 is a sealing plate. Reference numeral 10 is a metal spring, 11 is a valve body, 12 is a positive electrode lead body, 13 is an insulator, and 14 is an insulator.

The positive electrode 1 is a paste type nickel electrode produced as described above, and nickel hydroxide (provided that it becomes nickel oxyhydroxide at the time of discharging and at the time of charging) is used as an active material.

The negative electrode 2 is the hydrogen storage alloy electrode produced as described above, and has a composition of Ti ₁₅ Zr ₂₁ as an active material.
A hydrogen storage alloy represented by V ₁₅ Ni ₃₂ Cr ₅ Fe ₄ Co ₅ Mn ₃ is used.

The separator 3 is made of a grafted polypropylene non-woven fabric, and the positive electrode 1 and the negative electrode 2 are superposed on each other via the separator 3 and spirally wound to form a spiral electrode body 4.

The spiral electrode body 4 is housed in a battery case 5, and an insulator 14 is arranged on the spiral electrode body 4.

Further, the battery case 5 of the spiral electrode body 4 described above.
Prior to being housed inside, the insulator 1 is attached to the bottom of the battery case 5.
3 is arranged so that contact between the battery case 5 and the positive electrode 1 can be prevented.

The annular gasket 6 is made of nylon 66, the sealing lid 7 is composed of the terminal plate 8 and the sealing plate 9, and the opening of the battery case 5 is sealed by the sealing lid 7 and the annular gasket 6. There is.

The terminal plate 8 is provided with a gas discharge hole 8a,
The sealing plate 9 is provided with a gas detection hole 9a, and this terminal plate 8
And the sealing plate 9, the outer peripheral portion of the sealing plate 9 is bent and the terminal plate 8
It is fixed by sandwiching the outer peripheral part of the.

A metal spring 10 and a valve body 11 are provided inside the sealing lid 7 composed of the terminal plate 8 and the sealing plate 9.
And are housed.

The battery case 5 is made of cold-rolled steel and has a surface plated with nickel. After the spiral electrode body 4 and the like are inserted into the battery case 5, a part of the vicinity of the opening end is internally covered over the entire circumference. The inward projection 5a is formed by projecting inward, and the lower part of the annular gasket 6 is supported by the inward projection 5a.

That is, the annular gasket 6 and the sealing lid 7 are arranged in the opening of the battery case 5, the lower part of the annular gasket 6 is supported by the inward projection 5a, and the open end of the battery case 5 is inwardly moved. The opening of the battery case 5 is sealed by bending the annular gasket 6 against the sealing lid 7.

The positive electrode 1 is connected to the lower portion of the sealing plate 9 by the positive electrode lead body 12, so that the terminal plate 8 of the sealing lid 7 also serves as the positive electrode terminal, and the negative electrode 2 has its outer peripheral portion inside the battery case 5. It is pressed against the peripheral surface, and as a result, the battery case 5 also serves as a negative electrode terminal.

Then, as described above, this battery has a concentration of 3
A 0 wt% potassium hydroxide aqueous solution (however, lithium hydroxide is dissolved in 17 g / l) is injected as an electrolytic solution.

In this battery, under normal circumstances, the valve body 11 closes the gas detection hole 9a by the pressing force of the metal spring 10, so that the inside of the battery is kept in a hermetically sealed state. Occurs and the battery internal pressure rises,
The metal spring 10 contracts to form a gap between the valve body 11 and the gas detection hole 9a, and the gas inside the battery passes through the gas detection hole 9a and the gas discharge hole 8a and is discharged to the outside of the battery, causing the battery to burst. It is configured to prevent.

The characteristics of the above battery are that the standard capacity (1 V at a final voltage of 0.2 A discharge) is 1100 mAh and 1 A at room temperature.
The discharge capacity was 1000 mAh, and the discharge capacity at 0.5 A at 0 ° C. was 950 mAh.

The battery has a sufficiently low internal pressure of about 7 atmospheres when charged at 1 A for 1.5 hours, has a cycle life of 500 times or more, and has a capacity after storage at 20 ° C. for 30 days. The retention rate was as high as 80%, the cycle characteristics were excellent, and the self-discharge was small and the storage stability was excellent.

[0123]

As described above, according to the present invention, the battery characteristics could be improved, such as enhancing the hydrogen absorption / desorption capacity of the hydrogen storage alloy of the negative electrode and enhancing the charge / discharge efficiency.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an embodiment of a hydrogen storage alloy battery of the present invention.

[Explanation of symbols]

 1 Positive electrode 2 Negative electrode 3 Separator 4 Spiral electrode body 5 Battery case 6 Annular gasket 7 Sealing lid 8 Terminal plate 8a Gas discharge hole 9 Sealing plate 9a Gas detection hole 10 Metal spring 11 Valve body 12 Positive electrode lead body 13 Insulator 14 Insulator

Claims (1)

[Claims] 1. A hydrogen storage alloy battery having a negative electrode in which a hydrogen storage alloy powder is integrated with a metal porous body, a positive electrode, a separator, and an electrolytic solution, wherein two phases are included in the hydrogen storage alloy particles of the negative electrode. A hydrogen storage alloy battery, characterized in that particles containing the above phases are contained in an amount of 50% by volume or more.