JPS635866B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a sealed type substrate obtained by impregnating a sintered substrate obtained by sintering metal powder with nitrate of an active material, and then converting it into an active material, which is then housed in a container and sealed. This relates to the manufacturing method of alkaline storage batteries, in which a sealed alkaline storage battery is repeatedly charged and discharged in an open state, nitrate ions are converted to ammonia gas, which is eliminated, and at the same time, the batteries are raised to an appropriate range and charged, sealed, and sealed. The alkaline storage battery is anode-dominated.

Conventionally, sealed alkaline storage batteries using electrode plates in which a sintered substrate is impregnated with nitrate of an active material and used as an active material, have a sintered substrate impregnated with nitrate of an active material,
Next, the electrode plates were immersed in caustic soda or an aqueous caustic potash solution to make nitrate an active material, and then charged and discharged in a chemical conversion tank.
Problems such as part of the electrode plate peeling off occurred, especially on the anode plate. In order to prevent this, if the charge/discharge cycles are reduced and the formation is shortened, nitrate ions remain in the electrode plate, and as a result,
If this was incorporated into a storage battery as is, there would be drawbacks such as a high charging voltage, increased self-discharge, and inappropriate pull-up charging.

Therefore, in order to eliminate the above-mentioned drawbacks, the present invention impregnates a sintered electrode plate with nitrate as an active material, and then places a sintered electrode plate containing the nitrate as an active material in a storage battery container.
The battery is repeatedly charged and discharged in an open state to convert nitrate ions into ammonia and eliminate them, and at the same time, the battery is pulled up to an appropriate range and charged to control the anode of the sealed alkaline storage battery.

That is, the structure is such that a sintered substrate is impregnated with nitrate as an active material, and then the cathode and anode plates with the nitrate as the active material are housed in a storage battery container either as they are or after one cycle of chemical conversion is performed via a separator. The battery container is then sufficiently chemically formed by repeatedly charging and discharging the battery container for several cycles with the battery container open, and then the storage battery container is sealed when the battery container is in an overcharged state. .

Examples of the present invention will be described below.

A strip-shaped slurry-type sintered substrate is impregnated with nitrate as an active material by a known method, and then immersed in a caustic soda aqueous solution to turn the nitrate into an active material. Cut the chemically formed plate after 1 cycle and make the electrode plate size width 50
7 anodes and 8 cathodes are laminated with a separator in between, respectively, to form an electrode plate group of 60 mm in height and 1 mm in thickness.This is placed in a container, and the container is covered with a lid having a liquid injection port. The alkaline electrolyte is injected from the inlet, and with the container open, charging and discharging are performed for two cycles to perform chemical formation.Then, the electrode group is overcharged to complete the chemical formation, and the overcharge is completed. In this state, the liquid injection port was welded and sealed to produce a sealed alkaline storage battery. This storage battery is designated as A, and the sealed alkaline storage battery that was sealed as it is after injecting the electrolyte in the above is designated as B. Charge and discharge are performed for 9 cycles under the same conditions, and in the 10th cycle, the temperature is 13 °C, and the battery is charged at 1/4.5C. Figure 1 shows the charging characteristics when charging with current up to 1.45V. As is clear from FIG. 1, the cells that have been repeatedly charged and discharged for two cycles in the open state have lower charging voltages overall, and the time it takes to reach 1.45V is longer.

That is, it can be seen that a cell that has been charged and discharged for about two cycles in an open state has a higher capacity. That is, the nitrate ions in the electrode plate were changed into ammonia gas and quickly discharged, indicating that chemical formation was sufficiently performed. Moreover, there was no peeling on this electrode plate.
Note that when converting nitrate ions into ammonia, charging and discharging may be performed in an open state where ammonia gas is discharged. From this point of view, it is the same whether the test is carried out with the cell open or in another container, but in the former case, the anode and cathode plates are close together, so even if the cell is open there will be no overcharging. Oxygen generated from the anode is sometimes absorbed by the cathode plate, creating uncharged areas on the cathode plate. Therefore, even when overcharged, the cathode plate is not fully charged, but rather is charged to a moderately higher amount than the anode plate, and the uncharged portion is also formed to a moderate degree, allowing for a balanced pull-up charge within an appropriate range at the same time. This effect is achieved. In the latter case, when the electrode plate is moved from another container into the cell, discharge of the cathode plate occurs, making it doubtful whether the cathode plate has been pulled up and charged in a balanced manner; The charge decreases and it is difficult to manage the electrode plates. Therefore, in the former case, if the battery is sealed in an overcharged state, the amount of raised charge is contained. In other words, charging and discharging with the cell in an open state not only converts nitrate ions into ammonia, but also performs proper pull-up charging at the same time, which is different from the case with other containers. It's different.

Furthermore, if the strength of the sintered substrate is low, after three cycles of charging and discharging, a part of the electrode plate will be damaged.If the electrode plate is processed in this damaged state, problems such as electrode plate peeling may occur. be. In order to prevent this, if the anodizing current is reduced or the number of cycles is reduced, there is a problem that nitrate ions cannot be removed sufficiently. In other words, by preventing the electrode plates from peeling off or weakening,
It has the disadvantage that nitrate ions cannot be removed sufficiently, resulting in a high charging voltage. Pole plates with such defects are
It is advantageous to process the electrode plate when it has sufficient strength and remove the nitrate ions after assembling it into a cell. Alternatively, rather than re-forming the long-term abandoned electrode plate (because it is re-forming because the pull-up charge is gone),
It is easier to charge and discharge the cells in an open state, and it is also advantageous in terms of pulling up and charging.

As described above, according to the present invention, since the electrode plate group is charged and discharged in the storage battery container housing the electrode plate group with the storage battery container open to perform chemical formation, there is no peeling of the electrode plate, and the formation is sufficient. Nitrate ions are also removed, making it possible to keep the charging voltage low. Moreover, since the storage battery container is sealed when the electrode plate group is in an overcharged state, various effects such as a well-balanced charging portion for pulling up the cathode plate necessary for sealing can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a characteristic diagram showing the relationship between charging time and voltage.

Claims (1)

[Claims] 1 A sintered substrate is impregnated with nitrate as an active material, and then the cathode and anode plates with the nitrate as the active material are placed in a storage battery container via a separator, either as they are or after one cycle of chemical conversion. Manufacture of a sealed alkaline storage battery characterized in that the storage battery container is repeatedly charged and discharged for several cycles to sufficiently chemically form the battery container, and then the storage battery container is sealed with the electrode group in an overcharged state. Method.