JPS6290861A - Cadmium anode for alkaline storage battery - Google Patents

Abstract

PURPOSE:To suppress the generation of hydrogen by applying paste, which is composed mainly of one kind of cadmium oxide or cadmium hydroxide or metallic cadmium and includes antimony oxide or antimony hydroxide, to a conductive core body. CONSTITUTION:Antimony oxide such as antimony trioxide or tetraoxide or the like, or antimony hydroxide reacts with alkali, thereby producing highly- reductive antimonite such as potassium antimonite. Therefore, the antimonite is produced in a cadmium anode, to which active material paste including these materials as mentioned above is applied, by the injection of alkali electrolytic solution at the time of fabricating a battery. And cadimium hydroxide or cadmium oxide in the negative electrode is reduced. As a result, the conductive matrix of metallic cadmium can be formed in the anode in the battery and the highly active metallic cadmium can be prevented to oxidize in the air at the time of making the anode.

Description

[Detailed Description of the Invention] @) Paste-type cadmium P8bi for alkaline storage batteries, which is made by coating a conductive core with a conductive core. This invention relates to a cadmium cathode for alkaline storage batteries.

tc"l Prior Art 4 Alkaline 4-ton Ikegawa cadmium 44, which has an active material held in a core, is disclosed in Japanese Patent Application Laid-Open No. 132534/1983. This cadmium cathode is as shown in the above publication. After applying a paste containing a conductive core made of a porous base material such as a nickel wire wire mesh, cadmium oxide powder, gold-14 cadmium powder as a pre-charge amount, and a binder, it is dried and placed in an alkaline solution. It is manufactured without chemical conversion treatment.

However, although this unformed paste-type cadmium 14 electrode is pre-applied with metallic cadmium on the pre-charging surface, it may be oxidized by air before the battery is assembled, and the surface of the cadmium may become non-18 character. , - Because no conductive matrix is formed within the electrode, when rapidly charged at a large current of $ ah for 3 hours at room temperature, or for 10 hours J
Even with the following small current, when charging at a low temperature of around 0°C or lower, the magnetic conductivity inside the cathode is not sufficient, so batteries using this paste type cathode will have a high charge pressure. Hydrogen gas generation from the bottle becomes noticeable. This causes the internal gas pressure of the battery to become abnormally high, and in some cases, the full valve may operate, resulting in a problem that the battery usage conditions must be restricted.

Therefore, a reducing agent is mixed uniformly into the unformed cadmium cathode strip to reduce the cadmium oxide or cadmium hydroxide in the cathode to metallic cadmium, and the gold and lithium produced by this reduction are It is also thought that cadmium forms a conductive matrix within the cathode, but in this case the reduction occurs before battery assembly, and the metal cadmium produced by reduction is highly active, so it reacts with oxygen in the air and forms a cage. Because of the inconvenience of oxidation before assembly, sufficient effects could not be obtained.

r''1) Problems to be Solved by the Invention The present invention seeks to provide a cadmium cathode for alkaline storage batteries that suppresses hydrogen gas generation during low-temperature overcharging and rapid charging.

B)) Means for Solving the Problems The cadmium cathode for alkaline storage batteries of the present invention is mainly composed of at least one selected from cadmium oxide, cadmium saturated with water, or metal cadmium, and contains antimony oxide or antimony hydroxide. The paste is placed on a conductive core.

(Small) Action Antimony oxides and antimony hydroxides, such as antimony trioxide and antimony tetroxide, react with alkalis to form highly reducing antimonite salts such as potassium antimonite. Therefore, in the case of cadmium Yinran, which is made by applying an active material paste containing antimony oxide or antimony hydroxide to the magnetic conductive core, the alkali and antimony react with each other when the alkaline electrolyte is injected at the time of leaving the pond, resulting in reducing properties. Antimonite is produced, and the resulting antimonite salt reduces the cadmium hydroxide or cadmium oxide in the negative to form a conductive matrix of metallic cadmium in the @ electrode in the can.

Highly active metal cadmium conductor 1! Alkaline storage 1i with cadmium negative with matrix! yttt
can be obtained, and gold + t4 with high activity can be obtained as before.
This eliminates the inconvenience that cadmium oxidizes in the air during cathode production.

(Example [Example 1] 900 g of cadmium oxide and 100 g of metal cadmium as active materials, 6 g of human a-beef a pill cellulose as a binder, and 10 g of nylon fiber a as a reinforcing material.
, 300ac of 5% sodium phosphate aqueous solution, and oxidation 1
20g of silane and antimony oxide (SbzOs)2
A conductive core made of a nickel-plated punched steel plate with a thickness of 0.08U (the paste was applied and dried to form a cathode of the present invention) was Created.

[Example 2] A cathode f8) of the present invention was produced under the same conditions except that 7-gum oxidation laminate added to prevent the generation of cadmium dendrites from the composition of the negative Th tA+.

[Comparative Example 1] 1. 4 FCI was prepared under the same conditions except that anti-seven oxide was removed from the composition of i*m).

[Comparative Example 2] The shade f! In) except that antimony oxide was removed from the composition of In), In 14 (Dl) was produced under the same conditions.

Each of these 1 poles is 3QssX40- (theoretical capacity is approximately 80
After cutting to 0 mAH), a lead plate was attached to the test magnetic pole, and the test magnetic pole was immersed in a caustic potassium aqueous solution with a ratio of 27.

In this test at 0°C, a charging current of QjC is passed between the electrode and the counter electrode, and at this time, the hydrogen generated from the test is The amount of hydrogen collected and generated in the bucket was measured. Table 1 shows the amount of hydrogen generated at 0°C (accumulation).
This is the side of the charging site.

Table 1 Table ←No added antimony oxide@m tel and p)
Even if it spins, is hydrogen gas being generated from the beginning of charging?

In the cathode 41i of the present invention @A having a composition in which antimony oxide was added, and in the present invention cathode iH+ having a composition in which antimony oxide was added to the cathode (1)), no hydrogen gas generation was observed at the initial stage of charging, and Even during subsequent charging, hydrogen gas generation is kept low. It is known that the addition of O binding and antimony oxide to the cathode has a great effect on suppressing the generation of hydrogen gas.

0 is when p'4 h is immersed in an alkaline aqueous solution, the antimony oxide uniformly added to the cathode dissolves in the alkali to become a strongly reducing antimonite, and the reducing action of this antimonite salt This is thought to be because the dredged cadmium in the cathode turns into metal cadmium with good magnetic conductivity and forms a conductive matrix, and unlike the cathode fcl and p), which does not have a conductive 4E matrix, the charging reaction progresses and becomes destructive. (This is because the overvoltage of the cathode increases and hydrogen gas is easily generated.) It is thought that the charging reaction progresses evenly in the cathode of the present invention, suppressing the generation of hydrogen gas.

Next, the -3 poles β) to +D+ were each combined with a sintered nickel positive electrode via a nylon-free cloth as a separator, and an aqueous caustic potassium solution with a ratio fi + of 26 was added as an electrolyte to give a nominal volume of 1!1200 mAH. We prototyped a sealed nickel-cadmium battery. The batteries thus prepared were designated as batteries ^) to (D
1 of these ponds at room temperature. Charged with IC1J flow for 18 hours, then battery magnetic pressure reached 1. After discharging at a current of 1C until it reaches Ov, it is discharged at a current of 0.10 at a current of 1
An over-magnetization test was carried out for 1 week, and after the over-charge test, the partial pressure of the crushed hydrogen inside the battery was measured. This @Higashi is shown in the second table number.

Table 2 Batteries [Al to fD+ are all charged and charged at room temperature before entering the 0°C overcharging test, and a conductive matrix of gold rA cadmium is formed to the extent that it fits on the cathode. Despite this possibility, the difference in the hydrogen partial pressure of the &I14 cell was hidden, and the battery using the cathode of the present invention^) and G
The hydrogen partial pressure of BI is lower (suppressed) compared to batteries C) and p), which indicates that it is more effective in suppressing hydrogen gas generation.The reason for this is also 1c+ and (1)).
Since the 4-pole used for
In ii, the current is unrestricted or divided.

If the relative filling progresses and the wide part of the unfinished part becomes shallower, and if the depot invasion is carried out at 0℃ overfilling, then at the time of the cut-off filling (
In the charged part, charging does not progress smoothly (at the interface of the remaining part), the overvoltage gradually increases and hydrogen gas is generated. On the other hand, in 4 Ponds IAI and tel, 8 times negative f5I oxidized antimony is added, and this fecalized antimony dissolves in the positive potassium aqueous solution that is the electrolyte to become potassium antimonite and reduce cadmium oxide. ,
This is because a conductive matrix of gold and cadmium is uniformly formed in the cathode, which allows smooth charging to proceed between the four electrodes, suppressing the rise in overvoltage, and thereby suppressing hydrogen gas generation. Conceivable.

Next, other non-inventive examples will be shown below and compared with comparative examples.

[Example 3] A suspension prepared by mixing 5 parts of acetylene black, 7 parts of polyvinyl alcohol, and 100 parts of water by weight was applied to the surface of the cathode (Al) prepared in Example 1. L
, and then dried to produce a cathode of the present invention (El) having a carbon powder layer on the surface of the old R layer.

[Comparative Example 3] A negative itF+ was prepared by forming a carbon powder layer on the surface of the cathode fcl prepared in Comparative Example 1 in the same manner as in Example 3.

Using these cathode orientations and (Fl, hidden IA+ and difference), sealed nickel-cadmium 4
A prototype pond was made, the code of the cathode used was G, and then it was transferred to the battery) ρ++E+tF+, and after charging and discharging once under the same conditions as above, an OC overcharging angle test was performed, and after the overcharging test ζ The total pressure and hydrogen partial pressure inside the four ponds were measured. The results are shown in Table 3.T0The remainder after subtracting the hydrogen partial pressure from the total pressure is the steep partial pressure.

6th table cathode surface (this battery fEl and (Fl) are equipped with a cathode on which a carbon powder layer is formed. i) Gold and cadmium are easily formed near the cathode surface, and the gold 1rI4 cadmium formed near the cathode surface is likely to come into contact with oxygen gas generated from the anode during charging, so oxygen reacts with 7 and quenches the oxygen. af, the accumulation of oxygen gas and hydrogen gas decreases from d/semi+E) compared to ゛filling ratio^), and battery fFl from 4 cells). In addition, if the carbon powder layer is electrically connected to the 4iI core in advance, it is effective because cadmium is generated on the cathode surface early during charging and the oxygen absorption capacity is improved. It is sometimes possible to electrically connect the four-layer core and the carbon powder layer by mixing carbon fibers into the paste.
When the electrical connection is made by forming a matrix of cadmium as in the case of the present invention, it is advantageous that the active pore filling uncertainty can be increased compared to the case where carbon 4a is mixed.

(g) Effects of the invention Cadmium for alkaline storage batteries of the invention 1. The if electrode is mainly composed of at least one selected from cadmium oxide, cadmium hydroxide, or metal cadmium, and is formed by applying a paste containing antimony oxide or antimony hydroxide to a conductive core.

4 by said antimony oxide or antimony hydroxide
Ikeuchi I can form a conductive matrix of metallic cadmium in the cathode, which suppresses oxidation of the metallic cadmium in the cathode when it comes into contact with air during magnetic pole manufacture, and suppresses hydrogen gas generation. We can provide alkaline storage batteries with

Claims (1)

[Claims] (1) A cadmium cathode for an alkaline storage battery, which is mainly composed of at least one selected from cadmium oxide, cadmium hydroxide, or metal cadmium, and is made by applying a paste containing antimony oxide or antimony hydroxide to a conductive core.