JP3525519B2 - Hydrogen storage alloy electrode - Google Patents

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 electrode which is used in an electrochemical cell using hydrogen as an active material and is particularly applied as a reversible hydrogen electrode of a cell.

[0002]

2. Description of the Related Art In recent years, the applications of batteries are remarkably widespread, and primary batteries such as manganese batteries, lithium batteries, and alkaline batteries that can only be discharged, lead-acid batteries that can be repeatedly charged and discharged, and nickel batteries. There are secondary batteries such as cadmium storage batteries and silver oxide storage batteries. In addition to these, the active material is stored inside the batteries in such primary and secondary batteries, while fuel (reducing agent in a broad sense) is used. Fuel cells and the like have also been developed, in which oxygen and an oxidant in a broad sense are continuously supplied to generate electricity, and products are continuously taken out of the system.

A nickel-hydrogen secondary battery using a hydrogen storage alloy as a negative electrode of a secondary battery using hydrogen as an active material and nickel as an anode has also been developed.

[0004]

Even when a hydrogen storage alloy is used as the negative electrode of a secondary battery that uses hydrogen as an active material, it is possible to achieve excellent charging / discharging as with other secondary batteries and fuel cells. The challenge is to have characteristics.

[0005] The present invention was made in view of such conventional problems, in the case of using a hydrogen storage alloy as the negative electrode of the secondary battery, even more charge-discharge characteristics of the batteries of this An object is to provide a hydrogen storage alloy electrode that can be improved.

[0006]

In the hydrogen storage alloy electrode according to the present invention, the apparent density of the hydrogen storage alloy powder as the active material is 25% or more of the true density, as described in claim 1. It is characterized by being configured.

In the embodiment of the hydrogen storage alloy electrode according to the present invention, as described in claim 2,
The apparent density of the hydrogen-absorbing alloy powder as the active material can be 30% or more of the true density, and as described in claim 3, the hydrogen-absorbing alloy powder is a hydrogen-absorbing alloy containing hydrogen. It is possible to apply to crushed and crushed products.

In the present invention, the hydrogen storage alloy constituting the hydrogen storage alloy electrode includes Ti, Zr, V, Nb and T.
Some include elements that form metal hydrides such as a, La, and Pd. For example, TiNi-based, LaNi-based, La
There are a large number of Fe-based, ZrNi-based, ZrFe-based, etc., and it is possible to use binary, ternary, multi-component, etc. hydrogen storage alloys. The apparent density of the occlusion alloy powder is 25% or more of the true density, more preferably 30% or more.

[0009]

When a large amount of water is contained in the hydrogen storage alloy powder, the fluidity of the powder deteriorates, so that the apparent density of the hydrogen storage alloy powder decreases. Then, when such a hydrogen storage alloy powder having a low apparent density is used for a hydrogen storage alloy electrode, the amount of hydrogen storage alloy per unit volume is decreased due to poor filling, and the internal resistance is also increased, Although the charge / discharge characteristics of the battery are deteriorated, in the hydrogen storage alloy electrode according to the present invention, as described in claim 1, hydrogen storage alloy powder having an apparent density of 25% or more of the true density. That is, since the hydrogen storage alloy powder having an apparent density of 25% or more of the true density due to the small content of water etc. is used, the fluidity of the powder becomes good, When such a hydrogen storage alloy powder having a high apparent density is used for the electrode, the filling becomes good, the amount of hydrogen storage alloy per unit volume increases, and the internal resistance also decreases. Discharge characteristics become more that further improved.

And, as described in claim 2,
When the apparent density of the hydrogen storage alloy powder is 30% or more of the true density, the charge / discharge characteristics of the battery are further improved.

Further, as described in claim 3,
Even if the hydrogen storage alloy powder is obtained by pulverizing the hydrogen storage alloy by the hydrogenation pulverization method, the charge / discharge characteristics of the battery are further improved.

[0012]

EXAMPLES Zr: 32.2 atom%, V: 6.8 atom%,
Ni: 37.3 atom%, Mn: 20.3 atom%, Cr:
It has a composition of 3.4 atomic% and a true density of about 7.7 g / cm.
^The hydrogen storage alloy which is No. ³ is 150μ by the hydrogenation pulverization method.
Milled to m or less.

Then, the hydrogen storage alloy powder is vacuumed to a degree of 3
After drying at 100 ° C. for 1 hour in × 10 ⁻⁵ Torr, a part of the powder was taken out and mixed while spraying water onto the powder by spraying, and the apparent density shown in Table 1 was measured while measuring the apparent density. I adjusted it so that.

Next, each hydrogen storage alloy powder adjusted to the apparent density shown in Table 1 was rolled together with the Ni expanded metal to integrate the Ni expanded metal and the hydrogen storage alloy powder, and 900 ° C. in an Ar atmosphere. And sintered for 30 minutes.

Subsequently, the sintered hydrogen storage alloy electrode integrated with Ni expanded metal was used as a negative electrode, and a positive electrode made of nickel hydroxide was combined to form a secondary battery. 17mA per 1g of storage alloy
The discharge capacity of the negative electrode was measured by charging / discharging at the current value of.
The results are also shown in Table 1.

[0016]

[Table 1]

As shown in Table 1, when the apparent density of the hydrogen storage alloy powder is 25% or more of the true density, the discharge capacity of the negative electrode is about 370 mAh / g or more, and the secondary battery having good charge / discharge characteristics. It was possible to

[0018]

According to the hydrogen storage alloy electrode of the present invention, as described in claim 1, the hydrogen storage alloy powder as an active material has an apparent density of 25% or more of the true density. Therefore, it is possible to further improve the charge / discharge characteristics of the battery using such a hydrogen storage alloy electrode, and as described in claim 2, the apparent density of the hydrogen storage alloy powder. Is 30% or more of the true density, it is possible to further improve the charge / discharge characteristics of the battery. As described in claim 3, the hydrogen storage alloy powder is Even if the hydrogen storage alloy is hydrogenated and pulverized, the remarkably excellent effect that the charging / discharging characteristics of the battery can be further improved is brought about.

Claims (3)

(57) [Claims] 1. A hydrogen storage alloy electrode, wherein the apparent density of the hydrogen storage alloy powder as an active material is 25% or more of the true density. 2. The hydrogen storage alloy electrode according to claim 1, wherein the hydrogen storage alloy powder as the active material has an apparent density of 30% or more of the true density. 3. The hydrogen storage alloy electrode according to claim 1, wherein the hydrogen storage alloy powder is obtained by hydrogenating and pulverizing a hydrogen storage alloy.