JPS5836834B2 - Manufacturing method for sealed storage batteries - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a sealed storage battery, and provides a battery with good performance such as high rate discharge characteristics and life characteristics by a relatively simple method.

Conventionally, in this type of battery, the cathode is usually sealed with a larger charging capacity and discharging capacity than the anode.

This is to suppress the generation of hydrogen gas by leaving an uncharged portion on the cathode during overcharging, and to absorb oxygen gas generated from the anode to prevent an increase in internal gas pressure. This is to cope with the problem that when charging and discharging are repeated over a period of time, reaction substances generated at the cathode during discharging grow into stable crystals, making it difficult to react during charging and deteriorating the capacity.

This adjustment of the capacity of the anode and cathode is generally performed in a chemical formation process before sealing, and one method is to chemically form the anode and cathode after impregnation to adjust their capacity, and then stack them. There are some things that need to be sealed.

Another method is to stack the impregnated anode and cathode with a separator interposed therebetween, chemically form the anode and cathode to adjust the capacity, and then seal the anode and cathode.

However, in the former case, the charged active material in the cathode is easily oxidized by oxygen gas in the air during the period from oxidation to sealing, making it difficult to adjust the capacity.To prevent this, work must be done in an atmosphere free of oxygen gas. It was necessary to carry out the processes from chemical formation to assembly quickly.

However, even in the cathodes obtained in this manner, it was not possible to prevent variations in the respective capacities.

In the latter case, although capacity adjustment is relatively simple, the process becomes complicated and the cost of the battery inevitably increases significantly.

The present invention aims to eliminate the above drawbacks, and includes a step of bringing one cathode plate into a fully discharged state, a step of bringing the other cathode plate into a charged state, and electrically connecting each of the cathode plates. This method is characterized by the step of stacking a cathode in contact with a fully discharged anode having a smaller capacity than the cathode with a separator in between, and storing the stack in a container.

Hereinafter, an embodiment will be described in which the present invention is applied to a wound plate in which nickel is used as an anode active material and cadmium is used as a cathode active material.

A porous substrate obtained by sintering nickel powder is impregnated with a solution of nickel nitrate or cadmium chloride, and then subjected to negative electrolysis or neutralization in an alkaline solution to obtain hydroxide.

Next, the substrate is washed with water to remove the alkali content in the substrate, and then dried.

This process is repeated 7 to 8 times to fill the substrate with a predetermined amount of active material.

The anode and cathode thus obtained are subjected to chemical formation for the purpose of activating the active material, removing impurities, and adjusting the capacity.

The anode is subjected to one charging/discharging cycle with a current of 0.1 to 0.2 C to bring it into a fully discharged state, and then washed with water and dried.

The cathode is divided into two parts, and one of the cathode plates is charged and discharged for one cycle with a current of 0.1 to 0.2C in the same way as the anode, and after being completely discharged, it is washed with water and dried.

The other cathode plate is charged with a current of 0.1 to 0.2 C, or charged and discharged several times, and then charged to a charged state, and then washed with water and dried.

However, when the metal cadmium in the cathode plate in a charged state is washed with water and dried in the normal way, it is about 10% when washed with water and 60% when dried.
~70φ reacts with oxygen gas and water and becomes cadmium hydroxide.

That is, in the drying process, if the temperature of metal cadmium, which is easily oxidized even in the atmosphere, is carried out in an atmosphere containing sufficient oxygen gas and moisture, the drying time will be shortened, but oxidation will be accelerated.

Furthermore, even if the temperature is lowered, the drying time becomes longer and oxidation occurs to the same extent.

Therefore, it was found that if drying is carried out in a vacuum, the drying time will be shortened and oxidation will hardly proceed because the drying is carried out in the absence of oxygen gas.

The vacuum-dried cathode plate in a charged state※※ is stored in an atmosphere with low humidity or an atmosphere without oxygen gas.

Subsequently, the cathode plate in the discharged state and the cathode plate in the charged state are brought into electrical contact, and the anode in the discharged state is wound together with a separator interposed therebetween and housed in a metal container.

The battery thus obtained and the conventional battery have a nominal capacity of 1200 mAH, and the average discharge capacity when discharging at each current is the initial capacity and 2 of the normal charge and discharge.
Table 1 shows a comparison of the capacities at the 0th cycle.

Sample 1 is a battery in which the anode and cathode of a conventional battery have been chemically formed to adjust the capacity, and then rolled up and sealed. No. 3 is a battery manufactured by the method described above according to the present invention.

Next, Table 2 shows the capacity ratio of each capacity to the initial capacity of 0.20 discharge in the same sample as a percentage based on Table 1.

As is clear from the above results, it can be seen that the battery manufactured by the method of the present invention has good high rate discharge characteristics and good life characteristics.

The reason why the battery manufactured by the method according to the present invention has better characteristics than the battery manufactured by the method shown in Sample 1 is that while the capacity adjustment of the battery shown in Sample 1 is difficult and there are many variations. This seems to be because the capacity of the battery according to the present invention is reliably adjusted.Furthermore, the battery manufactured by the method shown in Sample 2 has the same characteristics as the battery according to the present invention, but The disadvantage is that the process is complicated and the cost is high.

Although an example in which the electrode plates are divided in the middle of the manufacturing process is shown as an embodiment of the present invention, it does not deviate from the gist of the present invention even if the electrode plates are divided from the beginning. The present invention provides a battery with good high rate discharge characteristics and long life characteristics using a relatively simple manufacturing method.

Claims (1)

[Claims] 1 A step of bringing one cathode plate into a fully discharged state, a step of bringing the other cathode plate into a charged state, and a cathode with a smaller capacity than the cathode in which each of the cathode plates is brought into electrical contact with the cathode, and a complete discharge with a smaller capacity than the cathode. 1. A method for manufacturing a sealed storage battery, comprising the steps of stacking a positive electrode and an anode with a separator interposed therebetween and storing the same in a metal container.