JPH0648623B2 - Hydrogen storage electrode - Google Patents

Description

TECHNICAL FIELD The present invention relates to a hydrogen storage electrode used as a negative electrode of a storage battery, and more particularly to a hydrogen storage electrode improved to maintain a high capacity for a long period of time.

(B) Conventional technology Lead-acid batteries and nickel-cadmium batteries have been commonly used in the past, but in recent years they are lighter in weight and have a higher capacity than those batteries. An electrode having a hydrogen storage alloy capable of reversibly storing and releasing hydrogen, which is an active material, was used as a negative electrode, and an electrode having a positive electrode active material made of metal oxide such as nickel hydroxide was used as a positive electrode. Metal-hydrogen alkaline storage batteries are receiving attention.

In general, a hydrogen storage electrode provided with a hydrogen storage alloy used in this type of storage battery is a mixture of an alloy powder that stores hydrogen and an alloy powder that does not store hydrogen, as proposed in Japanese Patent Publication No. 58-46827. A method of producing a sintered porous body by sintering and using it as a hydrogen storage electrode, or an alloy powder storing hydrogen and acetylene black and an electrode as proposed in JP-A-53-103541. It is manufactured by a method of forming a hydrogen storage electrode by bonding the support and a support with each other by an electrolytic solution resistant particulate binder, and one of the hydrogen storage alloys used for these electrodes is titanium-manganese binary. There are system alloys. However, the hydrogen storage electrode provided with this titanium-manganese binary alloy cannot obtain a sufficient capacity because the hydrogen storage amount is small, and the cycle life is not satisfactory.

(C) Problems to be Solved by the Invention In the hydrogen storage electrode of the present invention, an alloy containing a titanium-manganese alloy as a base and containing other elements is used for the negative electrode to increase the hydrogen storage capacity of the negative electrode. It is intended to improve the cycle life.

(D) Means for Solving the Problems The hydrogen storage electrode of the present invention is represented by TiMnx and x is 1.
Titanium or manganese of a titanium-manganese alloy satisfying 5 ≦ x ≦ 2 is replaced with Al, Si, Zn, Y, Nb, Hf, Ta.
At least one kind of element selected from the group consisting of TiNx and an alloy formed by substituting 0.4 atom or less per molecule of TiMnx.

(E) Operation The base titanium-manganese alloy is represented by TiMnx and x is 1.5 ≦ x ≦ 2, and titanium or manganese of this alloy is Al, Si, Zn, Y, Nb,
At least one alloy selected from Hf and Ta, Ti
When an alloy in which 0.4 atom or less per Mnx molecule is substituted is used as the hydrogen storage material of the negative electrode, the life of the hydrogen storage electrode which is the negative electrode is extended and the capacity is increased.

(F) Example Commercially available titanium, manganese, and aluminum in composition ratio,
Ti: Mn: Al = 1: 1.8: 0.2 are mixed, put in an arc melting furnace, heated, melted and alloyed to form TiMn.
1.8Al0.2 powder was obtained, and the operations of mixing, alloying and crushing were performed to obtain various hydrogen storage alloy powders having different compositions.

80% by weight of the various hydrogen-absorbing alloy powders thus obtained, 10% by weight of acetylene black as a conductive material, and 10% by weight of fluororesin powder as a binder were uniformly mixed with a mixer and the fluororesin was made into fibers to obtain The kneaded product thus obtained was wrapped in a nickel wire mesh and pressure-molded at 3 ton / cm ² , whereby a hydrogen storage electrode having an outer surface covered with the nickel wire mesh was produced. The alloy powder used for these hydrogen storage electrodes is about 1.5 g each.

Next, the theoretical capacity of each of the hydrogen storage electrodes is 600 mA.
Various sealed nickel-hydrogen alkaline storage batteries were prepared by using an aqueous solution of potassium hydroxide in combination with a sintered nickel positive electrode of H, and batteries A to A as shown in Table 1 depending on the type of hydrogen storage alloy used for the negative electrode. I. For comparison, batteries using titanium-manganese binary alloys having different compositions as the hydrogen storage material of the negative electrode were prepared, and the batteries J to M are shown in Table 1 depending on the type of the hydrogen storage material used.
After charging these batteries with 0.1C current for 16 hours, discharge them with 0.2C current and stop charging when the battery voltage reaches 1.0V. Repeat charging and discharging under the cycle condition to measure the battery characteristics. 1) to (M) are shown in Table 1, and the cycle characteristics of the batteries (A) to (K) are shown in FIG. 1 with the initial capacity of each battery being 100.

As is clear from Table 1, among the batteries (J) to (M) using the titanium-manganese binary alloy as the hydrogen storage material of the negative electrode, the discharge capacities of the batteries (J) and (K) are different from each other. Even if the same titanium-manganese binary alloy, which is larger than batteries (L) and (M), and whose composition is in the range of Mn1.5 to 2 with respect to Ti1, is used as the hydrogen storage material of the negative electrode, the discharge capacity is increased. I know that I can do it. In addition, the batteries (A) to (I) have a larger discharge capacity than the batteries (J) and (K), and the titanium-manganese binary alloy titanium or manganese is Al, Si, Zn, Y, N.
Further effects can be obtained by using the alloy prepared by partially substituting b, Hf, and Ta as the hydrogen storage material of the negative electrode. Regarding the cycle characteristics, as is clear from FIG. 1, the batteries (A) to (I) are superior to the batteries (J) and (K), and the titanium-manganese binary alloy titanium or manganese is added to the above various types. By partially substituting the element, the cycle characteristics as well as the discharge capacity are improved. The batteries (A), (B), (C), and (G) are used for discharge capacity, and batteries are used for cycle characteristics.
The effects are markedly shown in (D), (E) and (I).

Further, Table 2 shows that a titanium-manganese binary alloy composed of TiMn2 was used as a base, and an alloy produced by changing the amount of substituting elements was similarly used as a hydrogen storage material of the negative electrode to assemble a battery, and the discharge capacity of this battery was In comparison with the hydrogen storage alloy of the negative electrode, the amount of the element to be replaced is 0.4 atom or less per molecule of the base titanium-manganese binary alloy, and the discharge capacity is larger than that of the base TiMn2. On the other hand, when the number of atoms becomes 0.6, it decreases on the contrary. This is presumably because when the amount of the element to be replaced exceeds 0.4 atom per molecule of the titanium-manganese binary alloy, segregation of the replacing element occurs in the alloy and the alloy composition is not uniform.

As described above, titanium or manganese of a titanium-manganese alloy represented by TiMnx in which x is 1.5 or more and 2.0 or less is an element composed of Al, Si, Zn, Y, Nb, Hf, and Ta, and 0.4 atom or less per molecule of TiMnx. When the substituted alloy is used as the hydrogen storage material of the negative electrode, the discharge capacity and the cycle life are improved, but the same effect can be obtained even if two or more elements are substituted. The following is an example in which a titanium-manganese binary alloy is used as a base and an alloy substituted with two kinds of elements is used as a hydrogen storage material.

In the same operation as above, Ti0.8Ta0.2Mn1.8Al0.2, T
iMn1.6Al0.2Zn0.2 and Ti0.8Ta0.1Hf0.1M
Alloy powders made of n2 were prepared, and batteries were assembled using these alloys as the hydrogen storage material of the negative electrode, and the discharge capacity and cycle characteristics were measured. The batteries thus produced were made to correspond to the type of hydrogen storage alloy used for the negative electrode, and as batteries N, O and P shown in Table 3, their discharge capacities are simultaneously shown in Table 3 and their cycle characteristics are shown. It is shown in FIG. 2 together with the battery (K).

(G) Effect of the Invention The hydrogen storage electrode of the present invention is represented by TiMnx and x is 1.
Titanium or manganese of a titanium-manganese alloy satisfying 5 ≦ x ≦ 2 is replaced with Al, Si, Zn, Y, Nb, Hf, Ta.
To provide a storage battery having excellent performance, since it is provided with an alloy formed by substituting 0.4 atom or less per molecule of TiMnx with at least one element selected from the following, and it brings about improvement in discharge capacity and cycle characteristics. And its industrial value is extremely high.

[Brief description of drawings]

1 and 2 are cycle characteristic diagrams of a battery provided with the hydrogen storage electrode of the present invention and a comparative battery.

Claims (1)

[Claims] 1. A titanium-manganese alloy of titanium-manganese represented by TiMnx, wherein x is 1.5 ≦ x ≦ 2,
At least one element selected from Al, Si, zn, Y, Nb, Hf, and Ta, and 0.4 per molecule of TiMnx.
A hydrogen storage electrode comprising an alloy formed by substituting atoms or less.