JPH04206475A - Sealed alkali-zinc storage battery - Google Patents

Abstract

PURPOSE:To prevent the reduction of an electrolyte and an increase of the battery internal pressure due to the generation of hydrogen gas by using a material with a hydrogen ionization capability for part of an electrode or its lead section. CONSTITUTION:The capacity of a negative electrode 1 is made larger than the capacity of a positive electrode 2, and a material 12 with a hydrogen ionization capability is used for part of the positive electrode 2 and/or its lead section 4. Palladium belonging to the platinum group is used for the material 12 with the hydrogen ionization capability, it is carried by carbon, and part of it is kept in contact with an electrolyte. The hydrogen gas generated by the negative electrode 12 is absorbed by the material 12 with the hydrogen ionization capability used for part of the positive electrode 1 and/or its lead section. The material 12 with the hydrogen ionization capability is kept in contact with the electrolyte, and hydrogen ions are returned into the electrolyte. Even if water is decomposed to generate hydrogen gas, the reduction of the electrolyte is suppressed, and an increase of the battery internal pressure is suppressed.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a sealed alkaline zinc storage battery that uses zinc as the negative electrode active material.Prior art Alkaline storage batteries that use zinc as the active material have During overcharging, hydrogen gas is generated due to decomposition of water in the electrolyte during self-discharge of zinc.

At this time, hydrogen gas is not absorbed and accumulates inside the battery can.
This causes an increase in battery internal pressure and a decrease in electrolyte, reducing battery life and charging characteristics.

The following preventive measures can be taken to prevent this problem.

The first method is to absorb hydrogen gas using a hydrogen storage alloy.

The second method is to absorb hydrogen gas using a hydrogen storage alloy, and then react the hydrogen gas with oxygen gas generated from the positive electrode on a gas-phase reaction catalyst to return it to water. The third method is to suppress hydrogen gas generation by adding mercury to the zinc electrode.

Problems to be Solved by the Invention However, the first method cannot solve the problem of electrolyte reduction, and the second method uses water generated at the contact surface between the hydrogen storage material and the gas phase reaction catalyst to There is a problem that the absorption surface and the reaction surface are covered, and the hydrogen recycling reaction is inhibited, so that a sufficient effect cannot be obtained.Furthermore, the third method has the problem of pollution due to the use of mercury.

As described above, in a sealed alkaline zinc storage battery, hydrogen gas generation causes a decrease in the electrolyte and an increase in the internal pressure of the battery, which deteriorates the cycle life of the battery.

The present invention aims to solve the above problems and provide a battery with a long life.

Means for Solving the Problems The sealed alkaline zinc storage battery according to the present invention is characterized in that a material having hydrogen ionization ability is disposed on a portion of the electrode exposed to the gas phase within the battery or on its lead portion.

Hydrogen gas generated from the negative electrode is absorbed by a material having hydrogen ionization ability provided to a portion of the working electrode and/or its lead portion. Here, since the material having hydrogen ionization ability is in contact with the electrolyte, the hydrogen ions return to the electrolyte. Therefore, even if water decomposes and hydrogen gas is generated, a decrease in electrolyte solution can be suppressed, and at the same time, an increase in battery internal pressure can be suppressed.

At this time, water repellency is imparted to the material having hydrogen ionization ability in order to improve absorption of hydrogen gas.

Further, when a hydrogen storage alloy is used as a material having hydrogen ionization ability, it is coated with one or more of nickel, copper, and an element belonging to the platinum group to prevent oxidation. Therefore, the effect can be maintained for a long time.

Example Example A An embodiment of the present invention will be described with reference to the drawings.

As shown in Fig. 1, a separator 3 is arranged between a negative electrode 1 containing zinc and zinc oxide as living materials and a positive electrode 2 containing nickel hydroxide as an active material to form a spiral electrode body. This was inserted into battery case 7 to produce a cylindrical alkaline zinc storage battery (battery A of the present invention).

At this time, the capacity of the negative electrode 1 is made larger than the capacity of the positive electrode 2,
A part of the positive electrode and/or its lead portion 4 was provided with a material 12 having hydrogen ionization ability. The material with hydrogen ionization ability is palladium in the platinum group.
This was supported on carbon, and a portion of it was in contact with the electrolyte. In the figure, 5 is a negative electrode lead, 6 is a sealing plate, 8 is an insulating tube, 9 is a bottom insulating plate, 10 is a safety valve,
11 indicates an insulating packing.

Here, the material having hydrogen ionization ability was fixed to the lead portion of the electrode via a thin film of synthetic resin having a binder on both sides.

Examples B-G Batteries of the present invention B-G were prepared in the same manner as in Example A, except that materials having hydrogen ionization ability as shown in Table 1 were used.
was created. Here, a fluorine compound was sprayed onto each of the batteries C, D, and G in order to impart water repellency to the material having hydrogen ionization ability.

Table 1: 1. 1 Hydrogen 91' conversion ability...'''
Material I A I Balanoum supported on carbon was created.

As a comparative example, a comparative battery was prepared in the same manner as in Example A above, except that a material having hydrogen ionization ability was not applied to a part of the positive electrode and the lead portion.

Next, using these batteries, charge/discharge cycles, battery internal pressure, and battery weight were measured.

This charge/discharge cycle condition is to charge at a current value of 1/4C for 5 hours, and discharge at a current value of 1/4C until the battery voltage reaches 1.2V, and the discharge capacity is 60% of the initial capacity.
It is indicated by the number of cycles when it reaches 0%.

In addition, the internal pressure of the battery was measured by attaching a pressure sensor to a part of the battery case.

Table 2 shows the battery test results. As can be seen from the table, the battery of the present invention has improved cycle life compared to the comparative battery.
Battery internal pressure is also low.

It can also be seen that the decrease in electrolyte solution is also suppressed.

Table 2 [These results are considered to be due to the reasons shown below.

That is, in Batteries A, B, E, and F of the present invention, hydrogen gas generated during charging or self-discharge of zinc is absorbed by a part of the positive electrode and/or a material having hydrogen ionization ability provided to the lead portion. . Furthermore, since the material having hydrogen ionization ability is in contact with the electrolyte, hydrogen ions return to the electrolyte. Therefore, it is thought that an increase in battery internal pressure and a decrease in electrolyte solution are suppressed.

Next, the present invention batteries G and H are the above-mentioned present invention battery E.

The F hydrogen storage alloy is coated with Ni, which is thought to prevent the hydrogen storage alloy from oxidizing and further improve its hydrogen absorption capacity.

In addition, the present invention batteries C, D, I, and J are the above-mentioned present invention batteries A,
Water repellency is added to B, E, and F, and it is thought that this further improves hydrogen gas absorption and suppresses increases in battery internal pressure and decreases in electrolyte solution.

In contrast, in the comparative battery, during charging, hydrogen gas generated during self-discharge of zinc is not absorbed and accumulates inside the battery, which is thought to cause an increase in battery internal pressure and a decrease in electrolyte.

Note that the present invention is not limited to the above embodiments,
Changes may be made within the scope of the gist. For example, LaNi is a material with hydrogen ionization ability.
5 and MmNi5 were used, but instead of this, a part of Ni was replaced with Mn and Al.

It is also possible to use one substituted with Co or the like.

Effects of the Invention In the sealed alkaline zinc storage battery of the present invention, a part of the electrode or its lead portion is provided with a material having hydrogen ionization ability, which absorbs hydrogen gas and returns it to the electrolyte as hydrogen ions. I can do it.

Therefore, it is possible to prevent a decrease in electrolyte solution and an increase in battery internal pressure due to hydrogen gas generation during overcharging or self-discharge of zinc, and it is possible to provide a long-life alkaline zinc storage battery.

4.Kichi simple explanation FIG. 1 is a sectional view of the battery of the present invention.

1... Negative electrode, 2... Positive electrode, 3... Separator, 4
... Positive electrode lead, 5... Negative electrode lead, 12... Material having hydrogen ionization performance.

Name of agent: Patent attorney Akira Koeji and two others 1-・-
Go to L-9 C at Engo 2-1-Seimachi j-1.
- and Y Rulito 9---Y 6---1Tojiru 7--~Nurstoshane 1+1-pu 9-Botoko Seizu Junkei 0---Q≧〒Nanna Eyebrow Procedure Amendment Form June 1997 Person who makes the indications and amendments to the Jyohi 1 case Relationship with the も case Patent application Person name Address 1006 Kadoma in bold, Kadoma City, Osaka Prefecture Name (
582) Matsushita Electric Industrial Co., Ltd. Representative Akio Tanii 4 Agent 571 Address 1006-6 Oaza Kadoma, Kadoma City, Osaka Contents of amendment (1) “Electrodeposition and -11 of zinc
is corrected to "electricity and zinc".

(2)・In the same page, page 12, line 13, “partly and (in the lead part of the same)” is changed to “partly and 2・′ or in the lead part thereof.”
Correct it to 1.

Claims (12)

[Claims] (1) A sealed battery with a zinc negative electrode and a positive electrode made of a metal oxide built into a case, in which a material having hydrogen ionization ability is arranged on the part of the electrode exposed to the gas phase inside the battery or its lead part. Features: Sealed alkaline zinc storage battery. (2) The metal oxide constituting the positive electrode is nickel oxide, manganese oxide, a mixture thereof, or nickel,
The sealed alkaline zinc storage battery according to claim 1, which is a composite oxide of two or more metals selected from manganese, copper, silver, calcium, magnesium, cobalt, and cadmium. (3) The sealed alkaline zinc storage battery according to claim 1, wherein in the sealed battery, the capacity of the zinc negative electrode is larger than the capacity of the positive electrode. (4) The sealed alkaline zinc storage battery according to claim 1, wherein a part of the material having hydrogen ionization ability is in contact with the electrolyte. (5) The sealed alkaline zinc storage battery according to claim 1, wherein the material having hydrogen ionization ability is composed of a platinum group element and a carrier that holds it. (6) The sealed alkaline zinc storage battery according to claim 5, wherein the carrier holding the platinum group element is carbon. (7) The sealed alkaline zinc storage battery according to claim 5, wherein the carrier holding the platinum group element is alumina. (8) The sealed alkaline zinc storage battery according to claim 5, wherein the material having hydrogen ionization ability is imparted with water repellency. (9) The sealed alkaline zinc storage battery according to claim 1, wherein the material having hydrogen ionization ability is a hydrogen storage alloy. (10) The sealed alkaline zinc storage battery according to claim 9, wherein the hydrogen storage alloy is coated with one or more of nickel, copper, and platinum group metals. (11) The sealed alkaline zinc storage battery according to claim 9, wherein the material mainly consisting of a hydrogen storage alloy is imparted with water repellency. (12) The sealed alkali according to claim 1, wherein the material having hydrogen ionization ability is fixed to a part of the electrode or its lead part through a thin film of synthetic resin having a binder on both sides. Zinc storage battery.