JPS5831705B2 - Mitsupeishiki alkaline chikudenchi - Google Patents

Description

[Detailed description of the invention] The present invention relates to a sealed alkaline storage battery.

A typical example of this type of battery is the nickel-cadmium battery, in which the capacity of the cathode (cadmium hydroxide) is made smaller than the capacity of the anode (nickel hydroxide) in order to seal it. Even in a fully charged state, unreduced substances remain at the cathode, and the gas generated is only oxygen gas from the anode, and this oxygen gas is dissipated at the cathode.

For example, in batteries based on systems such as silver-zinc, nickel-zinc, and nickel-iron, materials that have high energy density, are relatively inexpensive, and are non-polluting are used as cathode active materials, so they are suitable for use as batteries. Although this is very advantageous, on the other hand, these cathode active materials react with the alkaline electrolyte (self-discharge) during storage and generate hydrogen gas.

Therefore, if the battery of the above system is sealed, even if the cathode capacity is made smaller than the anode capacity, hydrogen gas will be generated while the battery is left unused, and the internal pressure of the battery will rise, destroying the battery container or destroying it. Even if it does not reach this level, the safety valve will operate frequently, and as a result, the alkaline electrolyte becomes atomized and scatters outside, reducing the amount of liquid and deteriorating battery performance.Also, since alkaline electrolyte is corrosive, There is a risk of damaging the inside of the device in which the battery is installed.Furthermore, due to the frequent activation of the safety valve, hydrogen gas may be released to the outside of the battery and accumulate inside the device, causing a risk of ignition and explosion when the device switch is opened or closed.

As a method to solve this problem, a method has been proposed in which the hydrogen gas generated inside the battery is dissipated within the battery using a catalyst electrode, but the catalyst used is palladium, platinum, silver, etc. Since it is a precious metal, there was still a problem in terms of cost.

The object of the present invention is to make it possible to seal this type of battery, that is, a battery using a cathode active material that self-discharges and generates hydrogen gas when the battery is left unused, using an inexpensive hydrogen gas dissipating electrode. be.

Now, in the field of chemistry, particularly in the field of organic chemistry, nickel or a compound thereof (for example, 1-Raney nickel) has been effectively used as a hydrogenation catalyst.

Therefore, the present inventor investigated whether the above-mentioned nickel or its compound could be used for ion dissociation of hydrogen gas in a battery, that is, for the disappearance of hydrogen gas, and found that the porous electrode made of nickel or its compound could be used for the hydrogen standard electrode. It has been found that hydrogen gas can be eliminated at a potential of -0.3V to -0.8V.

Therefore, if the potential of the porous electrode can be continuously maintained within the above-mentioned range in a sealed state, it is possible to prevent the internal pressure of the battery from increasing due to the accumulation of hydrogen gas.

However, the potential of an electrode made of nickel or its compound is generally N100H+H20+e, =Nl(OH)2+
It shows the equilibrium potential of OH, which is approximately +0.5 V with respect to a hydrogen standard electrode in a basic electrolyte.

In other words, even if an electrode made of nickel or its compound is incorporated into a battery using a basic electrolyte using the normal method, it is possible to maintain the potential within the range of -0.3V to -0, SV based on electrochemical theory. It is impossible.

Focusing on this point, the present inventors contained a substance (for example, cobalt) in the porous electrode that has a potential of 10.73 V with respect to a hydrogen standard electrode in an alkaline electrolyte to reduce the potential of the porous electrode to -0. , 3V to -0.8V to eliminate hydrogen gas and seal this type of battery.

Next, one embodiment of the present invention will be described.

Dissolve CoSO4・7H20 in water to obtain a Co concentration of 50g/
Make a solution of metal C and use this as the electrolyte.

C on a Ni sintered plate made by sintering Ni powder with the plate as a counter electrode.
o is electrodeposited to form a hydrogen gas dissipation electrode.

The temperature of the electrolyte is 20 to 25°C, and the pH is 6 to 7.

Next, the amount of Co electrodeposited was examined, and it was confirmed that hydrogen gas was absorbed smoothly with the amount of electrodeposited when a current of 2 A was applied for 1 hour to a Ni sintered plate with an apparent surface area of 100 crit.

However, when current is applied in reverse for 30 minutes by two people, the amount of Co electrodeposited is small, so the potential of the Ni sintered plate becomes unstable and cannot be maintained at a potential suitable for hydrogen gas absorption.

Furthermore, when current is applied by two people for two hours, the surface of the Ni sintered plate is covered with a large amount of metal Co, which weakens the catalytic action of Ni and impairs hydrogen gas absorption.

From the above results, the amount of Co electrodeposited is 100% of the porous electrode surface area.
The optimum amount of electrodeposition is obtained when current is applied by two people for about 1 hour with respect to d.

Figure 1 is a schematic cross-sectional view of a sealed nickel-zinc battery using the hydrogen gas dissipation electrode described above, and 1 is an electrode group consisting of an anode using nickel hydroxide as an active material and a cathode using zinc as an active material. , 2 is hydrogen gas dissipation electrode, 3 and 4 are positive and
It is a negative terminal.

Note that the hydrogen gas dissipation electrode 2 is placed at the three-phase interface, and the amount of electrolyte is regulated.

Figure 2 is a characteristic diagram showing the relationship between the storage period after sealing and the battery internal pressure of a sealed nickel-zinc battery.The battery of the present invention has an extremely low battery internal pressure compared to conventional batteries that do not have a hydrogen gas dissipation electrode. It can be seen that it is retained.

Although it is not yet clear why hydrogen gas can be efficiently dissipated by regulating the potential of a porous electrode made of nickel or its compound to a potential of 10.3 V to O.S.V. relative to a hydrogen standard electrode. It is presumed that this is because nickel becomes active for ion dissociation of hydrogen gas in the above potential range.

As mentioned above, the present invention provides a battery in which a substance that generates hydrogen by reacting with an alkaline electrolyte, such as zinc or iron, is used as a cathode active material, in which an alkaline electrolyte is added to a hydrogen gas dissipating electrode made of nickel or a compound thereof. By regulating the hydrogen gas dissipation electrode to a potential of 10.3V to 10.8V, the internal battery can be kept safe while the battery is left unused. It is a device that continuously dissipates the hydrogen gas generated during hydrogen gas dissipation, and it is possible to seal this type of battery at low cost without using the expensive precious metals conventionally used as catalysts for hydrogen gas dissipation. Its industrial value is extremely high.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of the battery of the present invention, and FIG. 2 is a characteristic comparison diagram showing the relationship between battery internal pressure and storage period for the battery of the present invention and a conventional battery. 1...Main electrode group, 2...Hydrogen gas dissipation electrode, 3゜4...Positive/cathode terminal.

Claims (1)

[Claims] 1.Equipped with an anode made of silver or nickel as an active material, a cathode having a larger capacity than the anode and made of zinc or iron as an active material, and a hydrogen gas dissipation electrode made of nickel or a nickel compound, The electrode contains cobalt and has a voltage of 10.3 V to -0 compared to a standard hydrogen electrode.
, a sealed alkaline storage battery characterized by being regulated to a potential of 8V.