JPH061695B2 - Hydrogen storage electrode - Google Patents

Description

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

(B) Conventional technology Lead-acid batteries and nickel-cadmium batteries have been used as the storage batteries that have been often used in the past, but in recent years they are lighter in weight and have a higher capacity than those batteries. An electrode with a hydrogen storage alloy that can reversibly store and release hydrogen as an active material is used for the negative electrode, and an electrode with a positive electrode active material made of a metal oxide such as nickel hydroxide is used for the positive electrode. The metal-hydrogen alkaline storage battery that has been used has been receiving attention.

Generally, 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 this 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 binding the support and a support with each other by an electrolytic solution-resistant particulate binder. One of the hydrogen storage alloys used for these electrodes is JP-B-56-36786. There is a titanium-nickel binary alloy as shown in Japanese Patent Publication No. 56-48561. However, the hydrogen storage electrode provided with the TiNi alloy cannot obtain a sufficient capacity because the hydrogen storage amount of TiNi which is the hydrogen storage material is small, and the cycle life is not satisfactory.

(C) Problems to be solved by the present invention The present invention aims to increase the hydrogen storage capacity and the cycle life of the negative electrode by using an alloy containing TiNi as a base and containing other elements in the negative electrode. To do.

(D) Means for Solving Problems The hydrogen storage electrode of the present invention is based on a TiNi alloy, and nickel in the alloy is partially Al, Si, V, Mn, Zn, Nb, Mo,
It is provided with an alloy in which at least one element selected from

(E) Operation If a hydrogen storage alloy for the negative electrode is a TiNi-based alloy in which nickel in the alloy is partially replaced with at least one of the above elements, the life of the negative electrode hydrogen storage electrode is extended and the capacity is increased. To do.

(F) Example Commercially available titanium and nickel were mixed in a composition ratio of Ti: Ni = 1: 1, placed in an arc melting furnace, heated, melted, alloyed, and pulverized to obtain TiNi powder. It was

In addition, titanium, nickel and aluminum have a composition ratio of 1:
0.8: 0.2, mixed in the same manner, alloyed by heating and melting, and then pulverized to obtain TiNi0.8Al0.2 powder, and the operation of mixing, alloying and pulverizing the various hydrogen. An occlusion alloy powder was obtained.

80% by weight of the various hydrogen storage alloy powders thus obtained, 10% by weight of acetylene black as a conductive material, and 10% by weight of fluororesin powder as a binder are uniformly mixed with a mixer and the fluororesin is made into fibers. The resulting kneaded product was wrapped in nickel wire netting and pressure-molded at 3 ton / cm ² , so that the outer surface was covered with nickel wire netting to obtain a diameter of 2
Various circular hydrogen storage electrodes having a cm and a thickness of 1.2 mm were prepared.
The hydrogen storage electrode having a structure in which the outer surface is covered with a nickel wire mesh mechanically causes the expansion of the electrode that occurs when the hydrogen storage alloy in the electrode absorbs hydrogen and generates hydrogen gas during charging by the nickel wire mesh. The deterioration of the mechanical strength of the electrode due to the expansion of the electrode and the accompanying drop of the hydrogen storage alloy are suppressed, and the early deterioration of the performance due to the charge / discharge cycle is suppressed. The alloy powder used for these hydrogen storage electrodes is about 1.5 g each.

Then, the above hydrogen storage electrode was combined with a sintered nickel positive electrode having a theoretical capacity of 600 mAH to prepare a sealed nickel-hydrogen alkaline storage battery using an aqueous solution of potassium hydroxide as an electrolytic solution, and an alloy powder used as a hydrogen storage material for the negative electrode. These batteries are referred to as batteries A to H, as shown in Table 1. In addition, the discharge capacity at the time of repeatedly charging and discharging these batteries for 116 hours at 0.1 C current, discharging at 0.2 C current, and stopping the discharge when the battery voltage reached 1.0 V It is also shown in Table 1 and its cycle characteristics are shown with an initial capacity of 100.

From Table 1, batteries B to H having a negative electrode having a ternary alloy produced by partially replacing nickel in the alloy with another element based on TiNi all have a negative electrode having TiNi. It can be seen that the discharge capacity is larger than that of the battery A, the effects of the batteries B and E are particularly remarkable, and the discharge capacity is remarkably improved. Regarding the cycle characteristics, as is apparent from FIG. 1, the batteries B to H are improved as compared with the battery A, and the cycle characteristics of the batteries C, F and G are remarkably improved.

As described above, when an alloy containing various elements shown in Table 1 based on TiNi is used as the hydrogen storage material of the negative electrode, the discharge capacity and cycle characteristics are improved. Also, when a quaternary or higher alloy containing TiNi as a base and containing two or more kinds of elements is used, the discharge capacity and the cycle characteristics are improved. Therefore, it is possible to appropriately contain two or more kinds of elements according to the purpose. It is possible. An example in which a quaternary alloy based on TiNi is used as a hydrogen storage material for a negative electrode will be shown below.

Similar to the above, TiNi0.8Al0.1Mn0.1, TiNi0.7Al0.2Zn
Making an alloy powder consisting of 0.1 and TiNi0.8Mn0.1Nb0.1,
A battery was assembled using these alloys for the negative electrode, and the discharge capacity and cycle characteristics were measured. The batteries thus produced are designated as batteries I to K as shown in Table 2, the discharge capacity thereof is shown in Table 2, and the cycle characteristics are shown in FIG.

(F) Effect of the Invention The hydrogen storage electrode of the present invention is an alloy obtained by partially replacing nickel of the alloy represented by TiNi with at least one element selected from Al, Si, V, Mn, Zn, Nb and Mo. Since it is used as a hydrogen storage material and brings about improvement in discharge capacity and cycle characteristics, it is possible to provide a storage battery with excellent performance, and its industrial value is extremely large.

[Brief description of drawings]

1 and 2 are cycle characteristic diagrams of a battery using the hydrogen storage electrode of the present invention as a negative electrode and a comparative battery.

Claims (1)

[Claims] 1. A hydrogen comprising an alloy obtained by partially replacing nickel of an alloy represented by TiNi with at least one element selected from Al, Si, V, Mn, Zn, Nb and Mo. Storage electrode.