JPH06228699A - Hydrogen storage alloy - Google Patents

Abstract

PURPOSE:To produce a hydrogen storage alloy remarkably improved in the amt. of hydrogen to be occluded, plateau properties, response characteristics to the change of hydrogen pressure or the like, in a hydrogen storage alloy constituted of Ti, V and Ni, by prescribing each content of Ti, V and Ni. CONSTITUTION:In a hydrogen storage alloy expressed by the general formula: TixVyNiz, the compsn. (x) of Ti, the compsn. (y) of V and the compsn. (z) of Ni are limited to the range surrounded by the A point in th figure: Ti5V90Ni5, the B point: Ti5V75Ni20, the C point: Ti30V50Ni30 and the D point: Ti30V65Ni5 (namely, by atom, 5%<=x<=30%, 50%<=y<=90% and 5%<=z<=20%). Moreover, the range surrounded by the E point: Ti25V65Ni10, the F point: Ti15V75Ni10, the G point: Ti15V67.5Ni17.5 and the H point: Ti25V57.5Ni17.5 (namely, 15%<=x<=25%, 57.5%<=y<=75% and 10%<=z<=17.5%) is preferably regulated. In this way, the hydrogen storage alloy used for the hydrogen occlusion electrode of an alkali secondary battery or the like can be obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydrogen storage alloy used for a hydrogen storage electrode of an alkaline secondary battery.

[0002]

2. Description of the Related Art As conventional hydrogen storage alloys, for example,
The one described in JP-A-61-45563 is known. In this publication, a TiVNi-based hydrogen storage alloy used as an active material for a hydrogen storage electrode of a secondary battery, C
A TiVNi-based hydrogen storage alloy and a TiVZrNi hydrogen storage alloy further containing at least one of r, Zr, and Al, and a method for manufacturing a hydrogen storage electrode using such three types of hydrogen storage alloys are described. There is. According to the publication, the hydrogen storage electrode manufactured by using the three types of hydrogen storage alloys described above has a large hydrogen storage capacity,
It has advantages such as long cycle life and good discharge performance.

[0003]

DISCLOSURE OF THE INVENTION The present invention is disclosed in Japanese Patent Laid-Open No.
Of the three types of hydrogen storage alloys described in Japanese Patent Publication No. 45563/1994, which has a larger hydrogen storage capacity, shows better plateau characteristics, and is easily activated against hydrogen, and an alkaline secondary battery. An object is to provide a hydrogen storage alloy having good discharge characteristics when used as a negative electrode.

Here, the plateau characteristic means the hydrogen storage amount per unit amount of the hydrogen storage alloy, which is measured at a constant temperature.
The logarithm of hydrogen pressure, respectively, in the hydrogen storage amount-hydrogen pressure-temperature curve obtained by plotting on the horizontal axis and the vertical axis, when the hydrogen storage alloy is hydrogenated, or hydrogen from the hydrogenated hydrogen storage alloy Is the degree to which the portion corresponding to when the is dissociated is parallel to the horizontal axis, and the degree of hydrogen storage amount or hydrogen release amount with respect to a constant change in hydrogen pressure.

[0005]

The inventors of the present invention have
The discharge characteristics, plateau characteristics, easiness of hydrogenation and reactivity to hydrogen of iVN i-based hydrogen storage alloy, and its Ti,
The relationship with the composition of V and Ni was examined. As a result, T
If the composition of i, V and Ni is regulated within a predetermined range, TiVNi-based hydrogen storage alloy satisfying all of discharge characteristics, hydrogen storage capacity, plateau characteristics, easiness of hydrogenation and reactivity to hydrogen at the same time. The present invention has been completed by finding that the above can be obtained.

That is, the hydrogen storage alloy of the present invention is a hydrogen storage alloy represented by the general formula: Ti _x V _y Ni _{z, in} which the composition x of Ti, the composition y of V, and the composition z of Ni are: In atomic percent, A in the ternary composition diagram shown in FIG.
Point: Ti ₅ V ₉₀ Ni ₅ , Point B: Ti ₅ V ₇₅ Ni ₂₀ , C
It is characterized by being in a range surrounded by points: Ti ₃₀ V ₅₀ Ni ₂₀ and points D: Ti ₃₀ V ₆₅ Ni ₅ .

Hereinafter, the hydrogen of the present invention will be described with reference to FIG.
Storage alloy Ti_xV_yNi_zTi composition x, V composition y
And the reason why the composition z of Ni is limited as described above.
This will be described below. T than the AB line in the ternary composition diagram shown in FIG.
When the composition of i is small, for example, the composition x of Ti is 5
Child less than Ti_xV_yNi_zAlloy is the reaction rate with hydrogen
Is slow, that is, the reactivity to hydrogen is poor. As well
In addition, the composition of Ni is
When it is small, for example, the composition z of Ni is less than 5 atomic%.
Ti_xV_yNi_zAlloys have a slow reaction rate with hydrogen,
That is, this alloy has poor reactivity to hydrogen and
When used as the negative electrode of an alkaline secondary battery, the negative electrode is discharged.
The electric capacity is small and the charge / discharge characteristics are poor. Also shown in FIG.
If the Ni composition is higher than the BC line in the ternary composition diagram,
For example, Ti whose composition z of Ni exceeds 20 atomic%_xV_yN
i_zThe alloy is difficult to activate for hydrogen,
It cannot be activated at a temperature of about ℃. Also, FIG.
When the composition of Ti is larger than that of DC line in the ternary composition diagram shown in
In this case, for example, Ti with a composition x of Ti exceeding 30 atomic%
_xV_yNi_zAlloy, hydrogen storage capacity per unit amount of alloy
And its hydrogen storage capacity-hydrogen pressure-temperature curve
The plateau has a large inclination and is inferior in plateau characteristics
It cannot be converted.

For the reasons described above, the hydrogen absorption of the present invention is
Kura alloy Ti_xV_yNi_zTi composition x, V composition y
The composition z of Ni and Ni is indicated by point A in the ternary composition diagram shown in FIG.
Ti _FiveV₉₀Ni_Five, Point B: Ti_FiveV₇₅Ni₂₀, C point: T
i₃₀V₅₀Ni₂₀And point D: Ti₃₀V₆₅Ni_FiveSurrounded by
Limited to the range. That is, the hydrogen storage alloy T of the present invention
i_xV_yNi_zIn atomic percent of Ti
The composition x is 5% ≦ x ≦ 30%, and the V composition y is 50% ≦ y.
≤ 90% and Ni composition z limited to 5% ≤ z ≤ 20%
did.

Preferably, the composition x of Ti, the composition y of V, and the composition z of Ni are represented by E point: Ti ₂₅ V ₆₅ Ni ₁₀ , F point: Ti ₁₅ V in the ternary composition diagram shown in FIG. ₇₅ Ni ₁₀ , G
Point: Ti ₁₅ V _67.5 Ni _17.5 and H point: Ti ₂₅ V _57.5 N
It is better to limit to the range surrounded by i _17.5 . That is,
In the hydrogen storage alloy Ti _x V _y Ni _z of the present invention, the composition x of Ti is 15% ≦ x ≦ 25% in atomic percent.
In addition, it is preferable to limit the composition y of V to 57.5% ≦ y ≦ 75% and the composition z of Ni to 10% ≦ z ≦ 17.5%.
Ti composition x, the composition z of composition y and Ni and V, by limiting to such a range, the hydrogen storage alloy Ti _x V _y Ni _z of the present invention has a larger hydrogen storage capacity, and, It exhibits a better plateau characteristic and facilitates activation for hydrogen. Hereinafter, unless otherwise specified, the% notation relating to the composition means atomic%.

The hydrogen storage alloy of the present invention is made of Ti, V, Ni.
In addition to the above, other additional elements may be included. The additive element is added for the following purposes.
That is, in order to improve the hydrogen storage / release characteristics of the hydrogen storage alloy of the present invention such as adjusting the dissociation pressure of hydrogen and improving the plateau characteristic, the hydrogen storage alloy of the present invention is further treated with an alkali 2
When used as a negative electrode of a secondary battery, an additive element is added to improve the durability of the negative electrode during charging / discharging or high-rate discharging and to improve the conductivity of the negative electrode. . In addition, the additive element also plays a role as a binder that prevents the shape of the negative electrode from changing when charging / discharging and hydrogen storage / release are repeatedly performed.

In order to achieve the above-mentioned object, the hydrogen storage alloy of the present invention contains M in addition to Ti, V and Ni.
g, Al, Si, Ge, Cr, Mn, Fe, Co, C
u, Sr, Y, Zr, Nb, Mo, Pd, Ir, Ag,
At least one element of Hf, Ta, W, Pb, Bi and lanthanoid may be further included in a content of 8 atomic percent or less based on the total amount.

For example, in order to adjust the hydrogen dissociation pressure of the hydrogen storage alloy of the present invention to a low level, an additive element such as Y, Zr, Nb, Hf, or a lanthanoid having an atomic radius larger than Ti, V, or Ni is added. Is preferred. Further, in order to adjust the dissociation pressure of hydrogen of the hydrogen storage alloy of the present invention to be high, it is preferable to use an element having a relatively small atomic radius such as Mn, Fe, Co and Cu as an additional element.

In addition, the hydrogen storage alloy of the present invention is treated with alkali 2
When used as the negative electrode of a secondary battery, elements such as Cr, Al and Si that form stable oxides contribute to the improvement of the durability of the negative electrode during charge / discharge and high rate discharge. ,
It is preferable to use such an element as an additional element. Also, Pd
By using an element having a catalytic action for dissociating hydrogen molecules into atomic form, such as Ir or Ir, as an additive element of the hydrogen storage alloy of the present invention, the reaction rate of this hydrogen storage alloy with hydrogen can be accelerated. Furthermore, when the hydrogen storage alloy of the present invention is used in the negative electrode of an alkaline secondary battery, the conductivity of the negative electrode can be improved by using A that has spreadability and high conductivity.
It is preferable to use elements such as g and Cu as additional elements. A
When g or Cu is added, the conductivity of the obtained negative electrode is increased, the durability against electrode reaction is improved, and the obtained negative electrode is less likely to collapse.

Incidentally, Cr, Al, Si, Pd, Ir, A
When additional elements such as g and Cu are precipitated in the parent phase of the hydrogen storage alloy of the present invention, the above effects can be remarkably obtained. Thus, in order to precipitate the additional element in the matrix of the hydrogen storage alloy of the present invention, for example, the hydrogen storage alloy of the present invention excluding the additional element is previously melted, and the molten hydrogen storage alloy of the present invention is annealed by annealing. After the homogenization treatment, the additional element to be precipitated is dissolved in the mother phase of the hydrogen storage alloy of the present invention. Then, the annealing conditions after the melting of this additional element may be appropriately controlled.

The hydrogen storage alloy of the present invention is shown in FIG.
It can be manufactured according to the flow chart shown in FIG.
First, each constituent element is weighed and dissolved by an appropriate method. After this, if necessary, a homogenization treatment by annealing is performed. Then, the obtained hydrogen storage alloy of the present invention is pulverized into a powder having a predetermined particle size. After melting or annealing,
The obtained hydrogen storage alloy of the present invention may be subjected to hydrogenation and coarse pulverization and then pulverized to a powder having a predetermined particle size. When hydrogenation is carried out in this manner, a large number of cracks are generated in the hydrogen storage alloy of the present invention, and therefore it is necessary to subject the hydrogen storage alloy of the present invention to dehydrogenation as described below. However, the hydrogen storage alloy of the present invention can be easily pulverized into a powder having a predetermined particle size. Further, after carrying out hydrogenation and coarse pulverization, the obtained hydrogen storage alloy of the present invention having a coarse grain size may be dehydrogenated and then pulverized to a powder shape having a predetermined grain size. Furthermore, after carrying out hydrogenation and coarse pulverization, the obtained hydrogen storage alloy of the present invention having a coarse grain size may be pulverized to a powder form having a predetermined grain size and then subjected to dehydrogenation.

Here, as the hydrogenation method, the hydrogen storage alloy of the present invention is charged into a evacuated container, heated, and hydrogen is introduced into the container containing the heated hydrogen storage alloy of the present invention, and then the temperature is changed. And a method of lowering the temperature after heating the hydrogen storage alloy of the present invention in a hydrogen atmosphere. Particularly, in the latter method, if the pressure in the hydrogenation device is detected by a hydrogen pressure detection means or the like, the hydrogen storage alloy of the present invention is hydrogenated without opening the inside of the hydrogenation device to the atmosphere. Since it can be determined whether or not the manufacturing process is reduced, it is very effective.

When an element such as a lanthanoid having a very high oxygen activity is added to the hydrogen storage alloy of the present invention, hydrogenation and coarse pulverization are carried out, and then the hydrogen storage alloy of the present invention having a coarse particle size is obtained. It is necessary to dehydrogenate the alloy and to subsequently pulverize the dehydrogenated hydrogen storage alloy of the present invention in an inert gas atmosphere without exposing the dehydrogenated hydrogen storage alloy of the present invention to the air. is there. However, after undergoing hydrogenation and coarse crushing as described above, the hydrogen storage alloy of the present invention is often exposed to the air and crushed, and can be used without further dehydrogenation. it can. Further, depending on the application, the hydrogen storage alloy of the present invention may be used after being further classified.

[0018]

The hydrogen storage alloy Ti of the present invention_xV_yNi_z
Of Ti composition x, V composition y and Ni composition z
Point A of the ternary composition diagram shown in Fig. 1: Ti_FiveV₉₀Ni_Five, B
Point: Ti _FiveV₇₅Ni₂₀, C point: Ti₃₀V₅₀Ni₂₀and
Point D: Ti₃₀V₆₅Ni_FiveBe limited to the range enclosed by
According to the hydrogen storage alloy of the present invention,
-Total characteristics, easiness of hydrogenation and reactivity to hydrogen
Will be satisfied at the same time. Specifically,
The hydrogen storage alloy is described in JP-A-61-45563.
From a conventional hydrogen storage alloy composed of similar constituents
Also has a larger hydrogen storage capacity. Further, the hydrogen of the present invention
Hydrogen storage capacity of storage alloy-hydrogen pressure-temperature curve and conventional hydrogen
The hydrogen storage alloy of the present invention when compared with that of the storage alloy
Indicates a better plateau characteristic. That is, the present invention
The hydrogen storage alloy of is a large amount for small changes in hydrogen pressure.
It absorbs or releases hydrogen and responds to changes in hydrogen pressure.
The properties are better than those of conventional hydrogen storage alloys.

In addition, by limiting the constituents of the hydrogen storage alloy of the present invention to the ranges described above, the hydrogen storage alloy of the present invention can be activated for hydrogen at a temperature of 200 ° C. or lower in vacuum. It will be possible. Moreover, since the hydrogen storage alloy of the present invention does not contain a precious metal or a rare earth metal as a main constituent, it can be manufactured at a low manufacturing cost. That is, LaNi ₅ , Mm (Misch metal)
The hydrogen storage alloy of the present invention is cheaper than Ni ₅ and alloys having a composition containing these as the main components. Furthermore, since the hydrogen storage alloy of the present invention contains a large amount of Ti or V having a relatively small atomic weight, the hydrogen storage amount of the hydrogen storage alloy of the present invention per unit weight or discharge for a predetermined discharge current. The capacity is significantly improved.

[0020]

EXAMPLES The hydrogen storage alloy of the present invention will be specifically described below with reference to examples. Example 1 Ti _21.9 V _65.8 Ni _{12.3 in} atomic percent
A hydrogen storage alloy of Example 1 having the following composition was manufactured as follows. That is, the hydrogen storage alloy of Example 1 was
In the ternary composition diagram shown in FIG. 1, it has the composition indicated by the circle marked with # 1.

First, Ti, V and Ni are respectively
2.0470 g, 6.5437 g, and 1.4093 g were weighed. These constituents were melted by arc melting to obtain 10.000 g of alloy. Further, this alloy was annealed in vacuum at 900 ° C. for 48 hours to carry out a homogenization treatment. Then, the homogenized alloy was held at 500 ° C. for 30 minutes in a hydrogen atmosphere having a pressure of 5 MPa to obtain a hydride. Finally, this hydride was pulverized into powder having a particle size of 120 mesh or less to obtain the hydrogen storage alloy of Example 1.

The obtained hydrogen storage alloy of Example 1 was heated in vacuum at 500 ° C. for 240 minutes to be dehydrogenated to produce the hydrogen storage alloy of Example 1. Then, the dehydrogenated hydrogen storage alloy of Example 1 was analyzed by a powder X-ray diffraction analysis method. As a result, in the X-ray diffraction chart, the strongest line at the position of 0.214 nm was determined to be the surface spacing. The second strongest line at the position of 0.151 nm,
Appeared. Therefore, it was found that the hydrogen storage alloy of Example 1 was an alloy having a phase mainly composed of a body-centered cubic lattice.

Further, the hydrogen storage / release characteristics of the hydrogenated hydrogen storage alloy of Example 1 were evaluated using a Sibelts apparatus. As a result of evaluation using this Sibelts apparatus, the hydrogenated hydrogen storage alloy of Example 1 has a hydrogen storage / release characteristic represented by a hydrogen storage amount-hydrogen pressure-temperature curve as shown in FIG. understood. That is, the hydrogen storage alloy of Example 1, which was hydrogenated at about 40 ° C. and about normal pressure, can absorb and release hydrogen, and exhibits good plateau characteristics. Further, it is also found that the hydrogen storage amount of about 1% per unit weight of the hydrogenated hydrogen storage alloy of Example 1 can be effectively used.

Using the hydrogen storage alloy of Example 1 crushed into powder having a particle size of 120 mesh or less as described above,
A negative electrode for an alkaline secondary battery was manufactured according to the flowchart shown in FIG. First, the surface of the hydrogen storage alloy of Example 1 was washed with acid. Next, the surface of the hydrogen storage alloy powder of Example 1 that had been washed with acid was subjected to electroless copper plating, washed, and then dried. Then, the copper-plated hydrogen storage alloy of Example 1 was mixed with a predetermined amount of an organic binder. Further, the obtained mixture was pressed into a shape of an electrode by cold pressing. Finally, the pressed electrode was overlaid with a nickel mesh and hot pressed. As described above, a negative electrode with a nickel mesh for an alkaline secondary battery was manufactured.

Then, as shown in FIG. 5, the obtained nickel mesh-attached negative electrode 1 was placed in a casing 4 to form a positive electrode 2.
The glass filters 3 were opposed to each other. This positive electrode 2 is
It was composed of a foamed nickel plate and a nickel hydroxide powder filled in the small holes of the foamed nickel plate, which were sintered. Further, a mercury / mercuric oxide reference electrode 7 and a Luggin capillary 5 connected to a salt bridge 6 were arranged in the vicinity of the negative electrode 1 with a nickel mesh, and an electrolyte 8 such as potassium hydroxide was injected into the casing 4 as an electrolyte. As described above,
An alkaline secondary battery for evaluation was manufactured.

The discharge capacity per unit weight of the obtained alkaline secondary battery for evaluation was measured with a discharge current of 100 mA / g and a cut-off voltage of -0.7 V. As a result, the hydrogen storage alloy of Example 1 was used. Negative electrode with nickel mesh 1
The alkaline secondary battery for evaluation having No. 1 showed a discharge capacity-potential curve as shown in FIG. 6, and had a high discharge capacity per unit weight of 408 mAh / g. (Modification of Example 1) Ti _21.9 V in atomic percent
_{65.8 To} the hydrogen storage alloy of Example 1 having a composition of Ni _12.3 , each element of Y, Zr, Nb, La, Hf, Mn, Fe, Co and Cu was added by 5% with respect to the total amount. Nine kinds of hydrogen storage alloys, which are modified examples of Example 1, were manufactured.
Then, the dissociation pressure of hydrogen at 40 ° C. of these nine types of hydrogen storage alloys was measured.

As a result of this hydrogen dissociation pressure measurement, the hydrogen storage alloy of Example 1 showed a hydrogen dissociation pressure of 0.033 MPa. On the other hand, Y, Zr, Nb, Hf and La
5 types of hydrogen storage alloys, which are modified examples of Example 1 added with 0.005 MPa, 0.015 MPa, and
It showed reduced hydrogen dissociation pressures of 0.02 MPa, 0.005 MPa and 0.01 MPa. In addition, Mn, Fe,
The four types of hydrogen storage alloys, which are modified examples of Example 1 with Co and Cu added, are 0.11 MPa and 0.6, respectively.
It showed increased hydrogen dissociation pressures of MPa, 0.40 MPa, 0.50 MPa. That is, in order to adjust the hydrogen dissociation pressure of the hydrogen storage alloy of Example 1 to a lower level, Y, Zr,
In order to adjust the dissociation pressure of hydrogen in the hydrogen storage alloy of Example 1 to be high by adding an element having a relatively large atomic radius such as Nb, Hf and La, the atomic radius of Mn, Fe, Co and Cu should be adjusted. It has been proved that it is sufficient to add a relatively small element. (Example 2) Ti, V and Ni were respectively set to 2.22.
02 g, 7.0965 g, 0.6833 g, except that the same procedure as in the hydrogen storage alloy of Example 1 was followed except that Ti _23.5 V _70.6 Ni _{5.9 in} atomic percent was used.
A hydrogen storage alloy of Example 2 having the following composition was manufactured. That is, the hydrogen storage alloy of Example 2 has the composition indicated by the circle marked with # 2 in the ternary composition diagram shown in FIG.

Then, using the hydrogen storage alloy of Example 2, the same nickel mesh negative electrode 1 for an alkaline secondary battery as that produced by using the hydrogen storage alloy of Example 1 was used.
Was manufactured. Further, using the obtained nickel mesh-attached negative electrode 1, an alkaline secondary battery for evaluation as shown in FIG. 5 was manufactured. Similarly to the above, as a result of measurement at a discharge current of 100 mA / g, the alkaline secondary battery for evaluation having the negative electrode 1 with the nickel mesh made of the hydrogen storage alloy of Example 2 was discharged at a high unit weight of 180 mAh / g. It had a capacity. (Example 3) Ti, V and Ni were 2.07 respectively.
92 g, 6.6465 g, and 1.2743 g are only weighed, except that the hydrogen storage alloy of Example 1 is otherwise subjected to the same method as described above, but Ti _22.2 V _66.7 Ni _{11.1 in} atomic percent is used.
A hydrogen storage alloy of Example 3 having the following composition was manufactured. That is, the hydrogen storage alloy of Example 3 has the composition indicated by the circle marked with # 3 in the ternary composition diagram shown in FIG.

Then, using the hydrogen storage alloy of Example 3, the same nickel mesh negative electrode 1 for an alkaline secondary battery as that manufactured by using the hydrogen storage alloy of Example 1 was used.
Was manufactured. Further, using the obtained nickel mesh-attached negative electrode 1, an alkaline secondary battery for evaluation as shown in FIG. 5 was manufactured. Similarly to the above, as a result of measurement at a discharge current of 100 mA / g, the alkaline secondary battery for evaluation having the negative electrode 1 with the nickel mesh made of the hydrogen storage alloy of Example 3 was discharged at a high unit weight of 360 mAh / g. It had a capacity. Furthermore, the hydrogen storage alloy of Example 3 had a large hydrogen storage capacity similar to that of the hydrogen storage alloy of Example 1, exhibited good reactivity with hydrogen, and exhibited good plateau characteristics. (Example 4) Ti, V, and Ni were respectively set to 1.95.
15 g, 6.2487 g, 1.7998 g are different, except that the hydrogen storage alloy of Example 1 is otherwise treated in the same manner as atomic percentage Ti _21.0 V _63.2 Ni _15.8.
A hydrogen storage alloy of Example 4 having the following composition was manufactured. That is, the hydrogen storage alloy of Example 4 has a composition indicated by a circle with # 4 in the ternary composition diagram shown in FIG.

Then, the hydrogen storage alloy of Example 4 was used, and the same nickel mesh negative electrode 1 for an alkaline secondary battery as that produced using the hydrogen storage alloy of Example 1 was used.
Was manufactured. Further, using the obtained nickel mesh-attached negative electrode 1, an alkaline secondary battery for evaluation as shown in FIG. 5 was manufactured. Similarly to the above, as a result of measurement at a discharge current of 100 mA / g, the alkaline secondary battery for evaluation having the nickel mesh negative electrode 1 made of the hydrogen storage alloy of Example 4 showed a discharge per unit weight as high as 320 mAh / g. It had a capacity. Further, the hydrogen storage alloy of Example 4 had a large hydrogen storage capacity similar to that of the hydrogen storage alloy of Example 1, exhibited good reactivity with hydrogen, and exhibited good plateau characteristics. (Embodiment 5) Ti, V and Ni are respectively set to 1.84.
58 g, 5.8916 g, 2.2626 g are only weighed, except that the hydrogen storage alloy of Example 1 is otherwise subjected to the same method as Ti _20.0 V _60.0 Ni _{20.0 in} atomic percent.
A hydrogen storage alloy of Example 5 having the following composition was manufactured. That is, the hydrogen storage alloy of Example 5 has the composition indicated by the circle marked with # 5 in the ternary composition diagram shown in FIG.

Then, using the hydrogen storage alloy of Example 5, the same nickel mesh negative electrode 1 for an alkaline secondary battery as that manufactured by using the hydrogen storage alloy of Example 1 was used.
Was manufactured. Further, using the obtained nickel mesh-attached negative electrode 1, an alkaline secondary battery for evaluation as shown in FIG. 5 was manufactured. Similarly to the above, as a result of measurement at a discharge current of 100 mA / g, the alkaline secondary battery for evaluation having the negative electrode 1 with a nickel mesh made of the hydrogen storage alloy of Example 5 showed a discharge per unit weight as high as 220 mAh / g. It had a capacity. (Example 6) Ti, V, and Ni were each set to 0.93.
13 g, 7.9271 g, 1.1416 g are different, except that the hydrogen storage alloy of Example 1 is otherwise treated in the same manner as Ti _10.0 V _80.0 Ni _{10.0 in} atomic percent.
A hydrogen storage alloy of Example 6 having the following composition was manufactured. That is, the hydrogen storage alloy of Example 6 has the composition indicated by the circle with # 6 in the ternary composition diagram shown in FIG.

Then, the hydrogen storage alloy of Example 6 was used, and the same nickel mesh negative electrode 1 for an alkaline secondary battery as that produced by using the hydrogen storage alloy of Example 1 was used.
Was manufactured. Further, using the obtained nickel mesh-attached negative electrode 1, an alkaline secondary battery for evaluation as shown in FIG. 5 was manufactured. Similarly to the above, as a result of measurement with a discharge current of 100 mA / g, the alkaline secondary battery for evaluation having the negative electrode 1 with the nickel mesh made of the hydrogen storage alloy of Example 6 was discharged at a high unit weight of 280 mAh / g. It had a capacity. (Embodiment 7) Ti, V and Ni are respectively 1.88.
81 g, 7.5333 g, and 0.5786 g are different, except that the hydrogen storage alloy of Example 1 is otherwise treated in the same manner as Ti _20.0 V _75.0 Ni _5.0.
A hydrogen storage alloy of Example 7 having the following composition was manufactured. That is, the hydrogen storage alloy of Example 7 has a composition indicated by a circle with # 7 in the ternary composition diagram shown in FIG.

Then, using the hydrogen storage alloy of Example 7, the same nickel mesh negative electrode 1 for an alkaline secondary battery as that manufactured by using the hydrogen storage alloy of Example 1 was used.
Was manufactured. Further, using the obtained nickel mesh-attached negative electrode 1, an alkaline secondary battery for evaluation as shown in FIG. 5 was manufactured. Similar to the above, as a result of measurement at a discharge current of 100 mA / g, the alkaline secondary battery for evaluation having the nickel mesh negative electrode 1 made of the hydrogen storage alloy of Example 7 showed a discharge per unit weight as high as 160 mAh / g. It had a capacity. (Embodiment 8) Ti, V and Ni are respectively 2.84.
94 g, 6.5685 g, and 0.5821 g are different, except that the hydrogen storage alloy of Example 1 is otherwise treated in the same manner as Ti _30.0 V _65.0 Ni _{5.0 in} atomic percent.
A hydrogen storage alloy of Example 8 having the following composition was manufactured. That is, the hydrogen storage alloy of Example 8 has the composition indicated by the circle with # 8 in the ternary composition diagram shown in FIG.

Then, using the hydrogen storage alloy of Example 8, the same nickel mesh negative electrode 1 for an alkaline secondary battery as that manufactured by using the hydrogen storage alloy of Example 1 was used.
Was manufactured. Further, using the obtained nickel mesh-attached negative electrode 1, an alkaline secondary battery for evaluation as shown in FIG. 5 was manufactured. Similarly to the above, as a result of measurement at a discharge current of 100 mA / g, the evaluation alkaline secondary battery having the negative electrode 1 with a nickel mesh made of the hydrogen storage alloy of Example 8 showed a discharge per unit weight as high as 160 mAh / g. It had a capacity. Comparative Example 1 For comparison with the hydrogen storage alloy of the example,
Eight types of comparative hydrogen storage alloys having compositions of Ti, V, and Ni outside the scope of the claims of the present invention were manufactured as follows. First, Ti, V, and Ni are set to 1.744, respectively.
Hydrogen of Comparative Example 1 having the composition Ti _19.0 V _57.1 Ni _{23.8 in} atomic percent is the same as the hydrogen storage alloy of Example 1 except that 3 g, 5.5774 g and 2.6783 g are weighed. An occlusion alloy was produced. That is, the hydrogen storage alloy of Comparative Example 1 has a composition indicated by a cross with # C100 in the ternary composition diagram shown in FIG.

Then, using the hydrogen storage alloy of Comparative Example 1, the same nickel mesh negative electrode 1 for an alkaline secondary battery as that manufactured by using the hydrogen storage alloy of Example 1 was used.
Was manufactured. Further, using the obtained nickel mesh-attached negative electrode 1, an alkaline secondary battery for evaluation as shown in FIG. 5 was manufactured. Similarly to the above, as a result of measurement at a discharge current of 100 mA / g, the alkaline secondary battery for evaluation having the negative electrode 1 with the nickel mesh made of the hydrogen storage alloy of Comparative Example 1 was discharged at a low unit weight of 105 mAh / g. It had a capacity. Furthermore, it was difficult to hydrogenate the hydrogen storage alloy of Comparative Example 1 at a temperature of 200 ° C. or lower. (Comparative Example 2) Ti, V, and Ni were respectively 3.14.
50 g, 5.6974 g, and 1.5770 g are different, except that the hydrogen storage alloy of Example 1 is otherwise subjected to the same method as described above, but Ti _33.3 V _56.7 Ni _{10.0 in} atomic percent is used.
A hydrogen storage alloy of Comparative Example 2 having the following composition was manufactured. That is, the hydrogen storage alloy of Comparative Example 2 has the composition indicated by the cross mark with # C200 in the ternary composition diagram shown in FIG.

Then, the hydrogen storage alloy of Comparative Example 2 was used, and the same nickel mesh negative electrode 1 for an alkaline secondary battery as that manufactured by using the hydrogen storage alloy of Example 1 was used.
Was manufactured. Further, using the obtained nickel mesh-attached negative electrode 1, an alkaline secondary battery for evaluation as shown in FIG. 5 was manufactured. Similarly to the above, as a result of measurement at a discharge current of 100 mA / g, the alkaline secondary battery for evaluation having the negative electrode 1 with the nickel mesh made of the hydrogen storage alloy of Comparative Example 2 was discharged at a low unit weight of 130 mAh / g. It had a capacity. Further, in the hydrogen storage amount-hydrogen pressure-temperature curve shown by the hydrogen storage alloy of Comparative Example 2, the slope of the plateau was large, and the plateau characteristics of the hydrogen storage alloy of Comparative Example 2 were not suitable for practical use. (Comparative Example 3) Ti, V, and Ni were each set to 0.89.
75 g, 5.2520 g, 3.8505 g are different only in the same manner as in the hydrogen storage alloy of Example 1, except that the weight is adjusted to Ti _10.0 V _55.0 Ni _35.0.
A hydrogen storage alloy of Comparative Example 3 having the following composition was manufactured. That is, the hydrogen storage alloy of Comparative Example 3 has a composition indicated by a cross mark with # C300 in the ternary composition diagram shown in FIG.

Then, using the hydrogen storage alloy of Comparative Example 3, the same nickel mesh negative electrode 1 for alkaline secondary battery as that manufactured by using the hydrogen storage alloy of Example 1 was used.
Was manufactured. Further, using the obtained nickel mesh-attached negative electrode 1, an alkaline secondary battery for evaluation as shown in FIG. 5 was manufactured. Similar to the above, as a result of measurement at a discharge current of 100 mA / g, the alkaline secondary battery for evaluation having the negative electrode 1 with the nickel mesh made of the hydrogen storage alloy of Comparative Example 3 was discharged at a low unit weight of 110 mAh / g. It had a capacity. Further, it was difficult to hydrogenate the hydrogen storage alloy of Comparative Example 3 at a temperature of 200 ° C. or lower. (Comparative Example 4) Ti, V and Ni were 3.02, respectively.
92 g, 3.0681 g, and 3.9027 g are only weighed, except that the hydrogen storage alloy of Example 1 is otherwise subjected to the same method as Ti _33.3 V _31.7 Ni _35.0 atomic percent.
A hydrogen storage alloy of Comparative Example 4 having the following composition was manufactured. That is, the hydrogen storage alloy of Comparative Example 4 has a composition indicated by a cross with # C400 in the ternary composition diagram shown in FIG.

Then, using the hydrogen storage alloy of Comparative Example 4, the same nickel mesh negative electrode 1 for alkaline secondary battery as that manufactured by using the hydrogen storage alloy of Example 1 was used.
Was manufactured. Further, using the obtained nickel mesh-attached negative electrode 1, an alkaline secondary battery for evaluation as shown in FIG. 5 was manufactured. Similarly to the above, as a result of measurement with a discharge current of 100 mA / g, the alkaline secondary battery for evaluation having the negative electrode 1 with the nickel mesh made of the hydrogen storage alloy of Comparative Example 4 showed a discharge per unit weight as low as 48 mAh / g. It had a capacity. Furthermore, the hydrogen storage alloy of Comparative Example 4 was not only difficult to hydrogenate at a temperature of 200 ° C. or lower, but also in the hydrogen storage amount-hydrogen pressure-temperature curve shown by the hydrogen storage alloy of Comparative Example 4. The inclination of the plateau was large, and the plateau characteristics of the hydrogen storage alloy of Comparative Example 4 were not suitable for practical use. (Comparative Example 5) Ti, V, and Ni were each 0.91
41 g, 6.5648 g, 2.5211 g are only weighed, otherwise the same method as in the hydrogen storage alloy of Example 1 is used, with Ti _10.0 V _67.5 Ni _{22.5 in} atomic percent.
A hydrogen storage alloy of Comparative Example 5 having the following composition was manufactured. That is, the hydrogen storage alloy of Comparative Example 5 has a composition indicated by a cross with # C500 in the ternary composition diagram shown in FIG.

Then, using the hydrogen storage alloy of Comparative Example 5, the same nickel mesh negative electrode 1 for an alkaline secondary battery as that manufactured by using the hydrogen storage alloy of Example 1 was used.
Was manufactured. Further, using the obtained nickel mesh-attached negative electrode 1, an alkaline secondary battery for evaluation as shown in FIG. 5 was manufactured. Similarly to the above, as a result of measurement at a discharge current of 100 mA / g, the alkaline secondary battery for evaluation having the negative electrode 1 with the nickel mesh made of the hydrogen storage alloy of Comparative Example 5 showed a discharge per unit weight as low as 80 mAh / g. It had a capacity. Furthermore, it was difficult to hydrogenate the hydrogen storage alloy of Comparative Example 5 at a temperature of 200 ° C. or lower. (Comparative Example 6) Ti, V and Ni were 3.08, respectively.
60 g, 4.3581 g, and 2.5559 g are different, except that the hydrogen storage alloy of Example 1 is otherwise subjected to the same method as described above, but Ti _33.3 V _44.2 Ni _{22.5 in} atomic percent is used.
A hydrogen storage alloy of Comparative Example 6 having the following composition was manufactured. That is, the hydrogen storage alloy of Comparative Example 6 has a composition indicated by a cross with # C600 in the ternary composition diagram shown in FIG.

Then, using the hydrogen storage alloy of Comparative Example 6, the same nickel mesh negative electrode 1 for an alkaline secondary battery as that manufactured by using the hydrogen storage alloy of Example 1 was used.
Was manufactured. Further, using the obtained nickel mesh-attached negative electrode 1, an alkaline secondary battery for evaluation as shown in FIG. 5 was manufactured. Similarly to the above, as a result of measurement with a discharge current of 100 mA / g, the alkaline secondary battery for evaluation having the negative electrode 1 with a nickel mesh made of the hydrogen storage alloy of Comparative Example 6 was discharged at a low unit weight of 140 mAh / g. It had a capacity. Furthermore, the hydrogen storage alloy of Comparative Example 6 was not only difficult to hydrogenate at a temperature of 200 ° C. or lower, but also in the hydrogen storage amount-hydrogen pressure-temperature curve shown by the hydrogen storage alloy of Comparative Example 6. The inclination of the plateau was large, and the plateau characteristics of the hydrogen storage alloy of Comparative Example 6 were not suitable for practical use. (Comparative Example 7) The same method as in the hydrogen storage alloy of Example 1 was adopted except that 2.3865 g and 7.6144 g of Ti and V, respectively, were weighed without containing Ni at all. A hydrogen storage alloy of Comparative Example 7 having a composition of Ti _25.0 V _{75.0 in} atomic percent was produced. That is,
The hydrogen storage alloy of Comparative Example 7 has a composition indicated by a cross mark with # C700 in the ternary composition diagram shown in FIG.

Then, using the hydrogen storage alloy of Comparative Example 7, the same nickel mesh negative electrode 1 for an alkaline secondary battery as that manufactured by using the hydrogen storage alloy of Example 1 was used.
Was manufactured. Further, using the obtained nickel mesh-attached negative electrode 1, an alkaline secondary battery for evaluation as shown in FIG. 5 was manufactured. As a result of measurement at a discharge current of 100 mA / g in the same manner as described above, the alkaline secondary battery for evaluation having the nickel mesh negative electrode 1 made of the hydrogen storage alloy of Comparative Example 7 did not charge or discharge at all. (Comparative Example 8) The same method as in the hydrogen storage alloy of Example 1, except that Ni was not contained at all, and that Ti and V were weighed in 3.1938 g and 6.8062 g, respectively. A hydrogen storage alloy of Comparative Example 8 having a composition of Ti _33.3 V _{66.7 in} atomic percent was produced. That is,
The hydrogen storage alloy of Comparative Example 8 has a composition indicated by a cross with # C800 in the ternary composition diagram shown in FIG.

Then, using the hydrogen storage alloy of Comparative Example 8, the same nickel mesh negative electrode 1 for an alkaline secondary battery as that manufactured by using the hydrogen storage alloy of Example 1 was used.
Was manufactured. Further, using the obtained nickel mesh-attached negative electrode 1, an alkaline secondary battery for evaluation as shown in FIG. 5 was manufactured. Similarly to the above, as a result of measurement with a discharge current of 100 mA / g, the alkaline secondary battery for evaluation having the nickel mesh negative electrode 1 made of the hydrogen storage alloy of Comparative Example 8 did not charge or discharge at all. (Evaluation) The composition of Ni within the scope of the present invention, that is,
The hydrogen storage alloys of Examples 1 to 8 containing 5 to 20% of Ni could be hydrogenated at a temperature of 200 ° C. or lower in vacuum. On the other hand, the hydrogen storage alloys of Comparative Examples 1 and 3 to 6 containing more than 20% Ni were heated to at least 300 ° C. in a vacuum, and hydrogen was introduced unless hydrogen at a pressure of 3 MPa was introduced. I couldn't make it.

On the other hand, hydrogen storage alloys containing less than 5% Ni, such as the hydrogen storage alloys of Comparative Examples 7 and 8,
It was possible to hydrogenate below 200 ° C. However, the hydrogen storage alloys of Comparative Examples 7 and 8 had a significantly slow reaction rate with respect to hydrogen. In the hydrogen storage alloys of Examples 1 to 8 having the composition of Ni within the claims of the present invention, the larger the atomic percentage of Ni, the higher the dissociation pressure of hydrogen tended to be. Regarding the hydrogen storage amount, if the atomic ratio of V to the atomic percentage of Ti is the same, the hydrogen storage amount tends to decrease as the atomic percentage of Ni increases.

For reference, in the hydrogen storage alloy containing less than 5% Ni, the smaller the atomic percentage of Ni, the smaller the hydrogen storage amount tended to be. Further, when the hydrogen storage alloys of Comparative Examples 7 and 8 containing no Ni were used as an active material of a negative electrode for an alkaline secondary battery, such an alkaline secondary battery could be completely charged and discharged. could not.

On the other hand, in the hydrogen storage alloys of Examples 1 to 8 containing Ni of 5 to 20%, the atomic percentage of Ni was about 10 to 15%. The hydrogen storage alloy had the highest discharge capacity per unit weight. The effects on the physical properties of the hydrogen storage alloy when the composition of Ti was changed were as follows. If the ratio of the atomic percentage of Ni to the atomic percentage of V is the same, the larger the atomic percentage of Ti, the more the hydrogen storage amount tended to decrease. This decreasing tendency was remarkable when the atomic percentage of Ti was 25% or more. Furthermore, the larger the atomic percentage of Ti,
The dissociation pressure of hydrogen tended to be low. Furthermore, T
As the atomic percentage of i is larger, the plateau slope tends to be larger in the hydrogen storage amount-hydrogen pressure-temperature curve shown by the hydrogen storage alloy, and the hydrogen storage amount that can be practically used becomes smaller. , There was a risk that it would not be suitable for practical use. On the other hand, the smaller the atomic percentage of Ti, the slower the reaction rate for hydrogen.

Further, a Ti composition outside the scope of the present invention,
That is, the discharge capacity per unit weight of the hydrogen storage alloy containing Ti less than 5% or more than 30%, for example, the hydrogen storage alloys of Comparative Examples 2, 6 and 4 was not large. The effects on the physical properties of the hydrogen storage alloy when the composition of V was changed were as follows. The smaller the atomic percentage of V, the more the hydrogen storage amount tended to decrease. When a hydrogen storage alloy having a composition with a small atomic percentage of V is used as an active material of a negative electrode for an alkaline secondary battery, as a result, the discharge capacity of such an alkaline secondary battery for a given discharge current becomes small. It was not suitable for practical use.

As a whole, the hydrogen storage alloys of Examples 1 to 8 having the compositions within the claims of the present invention have a hydrogen storage amount of 1.4% by weight or more per unit weight and a temperature of 200 ° C. or less. The temperature range was 20 to 100 ° C., at which hydrogenation was possible and the hydrogen dissociation pressure was 0.1 MPa.
Thus, the hydrogen storage alloys of Examples 1 to 8 had practically suitable physical properties.

[0048]

As described above in detail, Ti composition x, V
The composition y of Ni and the composition z of Ni are shown in FIG. 1 at point A: Ti ₅ V ₉₀ Ni ₅ , point B: Ti ₅ V ₇₅ N
i ₂₀ , point C: Ti ₃₀ V ₅₀ Ni ₂₀ and point D: Ti ₃₀ V ₆₅
By limiting the range surrounded by Ni _5, the physical properties of the hydrogen storage alloy Ti _x V _y Ni _z of the present invention, for example, the hydrogen storage capacity, and response to changes in the plateau characteristics and the hydrogen pressure, the conventional hydrogen storage The physical properties of the alloy can be greatly improved.

[Brief description of drawings]

FIG. 1 is a ternary composition diagram of a hydrogen storage alloy Ti _x V _y Ni _z .

FIG. 2 is a flowchart showing an example of a method for producing a hydrogen storage alloy of the present invention.

FIG. 3 is a hydrogen storage amount-hydrogen pressure-temperature curve shown in Example 1 of the hydrogen storage alloy of the present invention.

FIG. 4 is a flowchart showing an example of a method for producing a negative electrode for an alkaline secondary battery using the hydrogen storage alloy of the present invention.

FIG. 5 is a schematic view of an alkaline secondary battery for evaluation manufactured using the hydrogen storage alloy of the present invention.

FIG. 6 is a diagram showing the relationship between the current capacity and the potential of the hydrogen storage alloy electrode of the alkaline secondary battery using the hydrogen storage alloy of Example 1 of the present invention.

[Explanation of symbols]

1: Hydrogen storage alloy electrode (negative electrode), 2: Nickel hydroxide electrode (positive electrode), 3: Glass filter, 4: Casing,
5: Luggin capillary, 6: Salt bridge, 7: Reference electrode, 8: Electrolyte

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kunio Takahashi 5-50, Hachiken-cho, Kariya city, Aichi Prefectural Institute for Imla Materials Development (72) Inventor Takahiro Mishima 5-chome, Hachiken-cho, Kariya city, Aichi prefecture Address Incorporated Imla Material Development Laboratory (72) Inventor Akito Isomura 5-50 Hachiken-cho, Kariya City, Aichi Incorporated Immura Material Development Laboratory (72) Inventor Sai Uehara 2 Fushiodai, Ikeda City, Osaka Prefecture Chome 3-12 (72) Inventor Keisuke Oguro 3-4-3 Satsukioka, Ikeda-shi, Osaka (72) Inventor Tetsuo Sakai 4-13-1, Tano, Amagasaki-shi, Hyogo Sonoda Daiya Heights 404 (72) Inventor Miyamura Hiro, 3-20-10, Shinsenri Nishimachi, Toyonaka City, Osaka Prefecture (72) Inventor Nobuhiro Kuriyama 3-13-12, Satsukioka, Ikeda City, Osaka Prefecture

Claims (3)

[Claims] 1. In a hydrogen storage alloy represented by the general formula: Ti _x V _y Ni _z , the composition x of Ti, the composition y of V, and the composition z of Ni are expressed in atomic percent as shown in FIG. Point A: Ti ₅ V ₉₀ Ni ₅ , point B: Ti ₅ V in the ternary composition diagram shown
₇₅ Ni ₂₀ , C point: Ti ₃₀ V ₅₀ Ni ₂₀ and D point: Ti ₃₀
A hydrogen storage alloy characterized by being in a range surrounded by V ₆₅ Ni ₅ . 2. A composition x of Ti, a composition y of V, and
The composition z of Ni is shown in FIG. 1 in atomic percent.
Point E of the ternary composition diagram: Ti_{twenty five}V₆₅Ni_Ten, F point: Ti₁₅V
₇₅Ni_Ten, G point: Ti₁₅V_67.5Ni_17.5And H point: T
i_{twenty five}V_57.5Ni _17.5It is in the range surrounded by.
Hydrogen storage alloy. 3. Mg, Al, Si, Ge, Cr, Mn, F
e, Co, Cu, Sr, Y, Zr, Nb, Mo, Pd,
The hydrogen storage alloy according to claim 1 or 2, further comprising at least one element selected from the group consisting of Ir, Ag, Hf, Ta, W, Pb, Bi and lanthanoid in a content of 8 atomic percent or less based on the total amount. .