JPS61168871A - Hydrogen occlusion electrode - Google Patents

Abstract

PURPOSE:To increase electrode life by using CaCU5 structure alloy prepared by including at least one of Si, Ti, V, Fe, Co, Zn, Y, Zr, Nb, Mo, Hf, Ta, and alkaline earth metal in Mischmetal and nickel. CONSTITUTION:Mischmetal, titanium, and nickel are mixed in a composition ratio of 0.9:0.1:5 and heated, melted, and allowed, then crushed to obtain Mm0.9Ti0.1Ni5 powder having CaCu5 crystal structure. A hydrogen occlusion electrode is produced with the hydrogen occlusion alloy powder obtained. By using the hydrogen occlusion electrode as a negative electrode of alkaline stor age battery, the battery maintains high capacity for a long time. Even if at least one of Si, V, Fe, Co, Zn, Y, Zr, Nb, Mo, Hf, Ta and alkaline earth metal is used instead of titanium in the above hydrogen occlusion alloy, the alkaline storage using this hydrogen occlusion electrode keeps high capacity for a long time.

Description

Detailed description of the invention (a) Industrial application field The present invention relates to a hydrogen storage electrode used as a negative electrode of an alkaline storage battery. (-related.

(b) Conventional technology Lead-acid batteries and nickel-cadmium batteries have traditionally been commonly used storage batteries, but in recent years they have been developed to be lighter than these batteries and have the potential to have higher capacities.
The negative electrode is an electrode equipped with a hydrogen storage alloy that can reversibly absorb and release hydrogen as a negative electrode active material under low pressure. A metal-hydrogen alkaline storage battery using a positive electrode of ff1g: is attracting attention.

General C: This type of storage battery C: The hydrogen storage electrode equipped with the hydrogen storage alloy used is disclosed in Japanese Patent Publication No. 58-46827≦;
C: A method of producing a sintered porous body by sintering a mixture of an alloy powder that absorbs hydrogen and an alloy powder that does not absorb hydrogen, and using this as a hydrogen absorbing electrode, as proposed in As proposed in Part 2 of Publication No. 53-103541, hydrogen-absorbing alloy powder, acetylene black, and an electrode support are combined with an electrolyte-resistant particulate binder (
;More mutually (;Method C:
These electrodes C: One of the hydrogen storage alloys used is CMmNi5 (Mm is Mitshu metal).However, this hydrogen storage electrode equipped with MmNi5 has a hydrogen storage capacity of MmNl6, which defines the electrode capacity. The amount was small, and the cycle life due to charge/discharge C was short, so it could not be said to be fully satisfactory.

(C) Problems to be solved by the present invention The present invention uses an alloy made of MmNi5 as a base and contains other elements as a negative electrode. This is what we are trying to measure.

2) Means for Solving the Problems The hydrogen storage electrode of the present invention is based on MmNie, and the alloy cst, 'ri, V, Fe, Co, Zn, Y, Zr.
, NblMo, Hf%Ta and 7/I/.

(E) Function MmNia is used as a hydrogen storage alloy for the negative electrode, and carbon containing at least one of the above elements is used.
When an alloy having an aCua crystal structure is used, the life of the hydrogen storage electrode, which is a negative electrode, is extended and the capacity is improved.

(f) Example Commercially available Mitsushi metal and nickel in composition ratio Mm:N
1=1:5c C; mix and arc melting furnace C;
It is heated, melted, alloyed, and then crushed to form MmNie.
A powder was obtained.

In addition, the composition ratio of Mitsushi metal, titanium, and nickel is M
Mix so that m=Ti:N1-Q, 9:α1:5C,
Similarly (=heating and melting 6; therefore, after alloying, pulverization is performed, and the crystal structure is CaCua @ 6Mma ml)
The Ti rhI Ni powder was obtained by the mixing, alloying and crushing operations described in Table 1 (
Various hydrogen storage alloys as shown in 2 were obtained.

Each of the thus obtained hydrogen-absorbing alloy powders (weight%), acetylene black (1011%) as a conductive material, and fluororesin powder (binder) (10% by weight) were uniformly mixed in a mixer using a mixer.
: When mixed, the C difluororesin is made into fibers. The obtained kneaded product was then wrapped in a nickel wire mesh and pressure-molded at 3 tons/- to produce various circular hydrogen storage electrodes with a diameter of 2 square meters and a thickness of tzm, the outer surface of which was covered with a nickel wire mesh.

The above-mentioned hydrogen storage electrode whose outer surface is covered with a nickel wire mesh is used during charging (C); when the hydrogen storage alloy in the electrode absorbs hydrogen (C); when hydrogen gas is generated and the electrode expands; This suppresses mechanical C: and suppresses the deterioration of the mechanical strength of the electrode due to the expansion zone of this polarization. do.

In addition, the alloy powder used for these hydrogen storage electrode C devices is approximately 152
It is.

Next, the above hydrogen storage electrode was combined with a sintered nickel positive electrode having a theoretical capacity of 600 mAH, and a sealed nickel-hydrogen alkaline storage battery was produced using electrolyte C: an aqueous potassium hydroxide solution. These batteries were charged with an α1C current for 16 hours, discharged with an α2C current, and then charged and discharged repeatedly under cycle conditions in which the discharge was stopped when the battery voltage reached toVc, and the discharge capacity was measured for each C2 capacity for 1110 cycles. The cycle life was measured by terminating the cycle when the capacity fell below 50% of the initial capacity. The results are shown in Table 1-2 in correspondence with negative electrode C; hydrogen storage alloy C used;

Table 1 From Table 1, MmN16%: As pace, Tl, Y, Z
It can be seen that the hydrogen storage electrode equipped with an alloy containing hydrogen, Nb, Mo, Hf, and Tai has a significantly improved cycle life compared to a hydrogen storage electrode equipped with MmNie as a hydrogen storage material.

Also, is it the same as MmNlst-pace and contains the former? :Nine batteries were prepared using variously modified alloys as negative electrode C devices, and the discharge capacities of the four batteries were measured. This result is 1kI
J! Table 12 (: shows.

Table 2 From Table 2, MmNi sg base x and 1. te s　l,V.

Hydrogen storage electrodes equipped with alloys containing Fe, Co, Zn, and alkaline earth metals such as Mg%Ca, Sr%Bm have increased discharge capacity compared to hydrogen storage electrode C equipped with MmNi5 as a hydrogen storage material. I understand that.

Further, as shown in 1 below, when an alloy containing two or more types of elements using MmNia as a pace is used, the cycle life and discharge capacity are also improved. Therefore, it is possible to contain two or more types of elements as appropriate depending on the purpose.

Same as above (;shiteMmagTiaxZraINit
An alloy powder consisting of 8s i (L2) was prepared, and a battery was assembled using this metal-containing material as the negative electrode C; and the cycle life and discharge capacity were measured. The results are shown in Table 5.

Table 5 (G) Effects of the Invention The hydrogen storage electrode of the present invention contains minsch metal-nickel alloys i2s1, T1, V, Fe, Co, and Zn.

Ca containing at least one element selected from Y, Zr, Nb, Mo, Hf, Ta and alkaline earth metals
It is equipped with an alloy having a Cuall crystal structure, and can provide a storage battery with improved cycle characteristics and increased discharge capacity due to increased hydrogen storage capacity. The value is extremely high.

Claims (1)

[Claims] (1) Mitsushi Metal - Nickel alloy with Si, Ti, and V
, Fe, Co, Zn, Y, Zr, Nb, Mo, Hf, T
A hydrogen storage electrode comprising an alloy having a crystal structure of CaCu_5 structure and containing at least one element selected from a and alkaline earth metals.