JPS59184456A - Formation of sealed lead storage battery - Google Patents

Abstract

PURPOSE:To improve the overcharge resistant performance of a sealed lead storage battery, in which unformed positive and negative plates are subjected to formation in a container, by carrying out the formation in two stages. CONSTITUTION:The first formation in which a positive plate influencing the overcharge performance is principally formed and the second formation in which the amount and the concentration of electrolyte is adjusted to given levels during and at the end are separately carried out. In the first formation, it is preferred that a small amount of dilute sulfuric acid with a low concentration is used as electrolyte to be poured. It has been found that a good result is obtained by adjusting the formation efficiency (content of lead oxide in an active material) to over 50%. In the second formation, oxygen gas is not absorbed by the negative electrode in the early stage, and formation of the positive and the negative plates is completed by adding electrolyte consisting of dilute sulfuric acid with a higher concentration than that poured in the first formation so that given amount and concentration of electrolyte is achieved at the end of the formation. As a result, the overcharge resistant performance is improved, a high formation efficiency of the positive plate is achieved, and a high capacity is obtained in the early stage.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for chemically forming a sealed lead-acid battery in a container in which the amount of electrolyte is limited and there is no free electrolyte. Structure and its problems Sealed lead-acid batteries prevent electrolyte loss by absorbing oxygen gas generated from the positive electrode into the negative electrode during charging.
−Therefore, a gas layer (oxygen) is added to the negative electrode so that it can absorb oxygen.
and the liquid layer (electrolyte) must be in contact at the same time. In this state, the negative electrode is charging and discharging at the same time, so it is impossible to chemically form the unformed electrode plate. Therefore, in sealed lead-acid batteries, a chemical conversion process is generally performed outside the battery case to change the positive electrode active material to lead dioxide and the negative electrode active material to lead, respectively, before battery assembly.

However, chemical conversion outside the battery case requires immediate drying treatment to prevent oxidative deterioration of the active material, and requires charging for activation after battery assembly, making the battery manufacturing process complicated and costly. It was high.

As a way to solve these problems, it has been proposed to chemically form the electrode plates inside the battery container.In other words, a group of electrode plates consisting of an unformed positive electrode plate, a negative electrode plate, and a glass mat separator that can hold and absorb electrolyte is placed inside the battery container. At the same time, it is charged by adding electrolyte solution in an amount that does not cause the negative electrode to absorb oxygen gas. After the negative electrode has completed its formation, the formation of the positive electrode is completed by further charging, and at the same time, the electrolyte is applied to increase the oxygen gas absorption capacity of the negative electrode.

As a result, immediate drying treatment and charging after battery assembly, which are required when chemical conversion is performed outside the battery case, are no longer necessary. Although this was a great advantage in terms of mass production, batteries made using this manufacturing method were susceptible to overcharging due to the formation of a passive film at the interface between the positive electrode lattice and the positive electrode active material. It was found that the capacity decreases early.

OBJECTS OF THE INVENTION The object of the present invention is to improve the overcharge resistance of a sealed lead-acid battery in which both the positive and negative electrodes are chemically formed in the battery case using unformed plates, by improving the chemical formation method.

Structure of the Invention The present invention comprises a tenth chemical formation step in which the positive electrode plate, which affects overcharge performance, is mainly chemically formed, and a second chemical formation step in which the negative electrode plate is formed and a predetermined electrolyte amount and concentration are achieved at the end of the formation. It is characterized by separating the electrolyte, reducing the amount of electrolyte in the first chemical conversion step, and preferably performing the entire chemical conversion in a small amount of low-concentration dilute sulfuric acid.1. It has been found that sealed lead-acid batteries subjected to chemical formation have poor overcharging resistance, and their capacity decreases due to an overcharged electricity amount of 15 to 20 times the battery capacity (10 hour rate). It has been found that this is due to deterioration of the positive electrode plate, and occurs because the adhesion between the positive electrode grid and the positive electrode active material decreases. The reason for this is that in order to obtain a predetermined amount and concentration of electrolyte at the end of chemical formation, a high concentration dilute sulfuric acid electrolyte is added to the entire chemical formation. If such chemical formation is performed, the adhesion between the positive electrode lattice and the active material decreases, and when a portion around the positive electrode lattice is discharged, a passive film is formed and deposits occur, making it impossible to discharge.

Therefore, in the first chemical formation step, the amount of electrolyte injected is preferably a small amount, and dilute sulfuric acid with a low concentration is preferable. It was found that it is effective to increase the ratio to 50% or more. In addition, the electrolyte in the first chemical formation process reacts with the positive and negative electrode plates to form lead sulfate after injection, so if the amount of liquid is small and the concentration is low, the electrolyte during formation will be almost neutral. As the lead becomes closer to the lead, the solubility of lead increases and becomes sulfur/yon, which tends to cause internal short circuits. However, these can be prevented by adding a neutral salt consisting of sulfuric acid or magnesium sulfate to the electrolytic solution at 0.1 to 5% by weight. If it is less than .1% by weight, there is no effect, and if it is more than 5% by weight, the discharge capacity decreases, which is not preferable.

The second chemical conversion step is performed continuously after the tenth chemical conversion step. In the first chemical formation step, the positive electrode formation progress is 50%
As described above, the negative electrode plate absorbs all the oxygen gas generated from the positive electrode due to the low electrolyte state, and the conversion progress rate stops at around 60%. Therefore, in the second chemical formation step, the amount of the electrolyte is lower than that injected in the tenth chemical formation step, so that oxygen gas absorption at the negative electrode is not carried out at the early stage of formation, and at the end of formation, the electrolyte has a predetermined amount and concentration. An electrolytic solution consisting of highly concentrated dilute sulfuric acid is added to complete the formation of the positive and negative electrode plates.

DESCRIPTION OF EMBODIMENTS Specification of a method for forming a battery case for a battery having a 1o hour rate capacity of 3 Ah, in which a group of electrode plates consisting of an unformed positive electrode plate, a negative electrode plate, and a glass mat separator capable of retaining and absorbing electrolytic Me is housed in a battery case. An example is given below.

(First chemical conversion step) An electrolytic solution prepared by adding 0.39 sodium sulfate to 16.5 ml of dilute sulfuric acid with a concentration of 1Q% by weight was injected into the battery cell, and a square was placed to prevent oxygen from entering the battery from the outside. Thereafter, a current of 0.3 A is applied for 26 hours to perform chemical conversion. At this time, the degree of chemical formation of the positive electrode plate was approximately 70%.

(Second chemical conversion step) After the first chemical conversion step, 9 mL of dilute sulfuric acid 1a, 46% by weight was added to the electrolytic solution in the container, and after applying a valve in the same manner as in the first chemical conversion step, A current of 0.3 A was applied for 15 hours to complete the chemical formation.

By performing this first chemical conversion step and the second chemical conversion step, the battery container formation is completed. After completion of chemical formation, the dilute sulfuric acid electrolyte was adjusted to a concentration of 41.5% by weight and a liquid volume of 27m4. This amount of electrolyte is free of loose and free electrolyte.

Next, the results of the overcharge performance of the battery (A) produced by the chemical formation method of the present invention and the battery (B) produced by the conventional chemical formation method are shown below.

The battery produced by the chemical conversion method of the present invention is as follows.
o hourly rate and a capacity of 3 Ah.

On the other hand, conventional tank chemical treatment uses dilute sulfuric acid with a concentration of 31% by weight.
After adding 11 um gold sulfate to 3 ml (l) and injecting the solution, a valve was installed to prevent oxygen from entering the battery from the outside, and the temperature was 0.
．． The battery was charged at 3-A for 4Q hours. The amount and concentration of electrolyte after charging were the same as those of the present invention. The charge qA obtained by the chemical conversion method of the present invention and the battery B obtained by the conventional chemical conversion method were set to 0.
The figure shows the change in capacity when overcharging is performed at 050 (0,154).

The capacity is 0.20 (o, e
Measurements were made based on the discharge duration until the voltage decreased to 10.5V after discharging at A). From these results, it was found that the chemical conversion method of the present invention has significantly improved overcharge resistance performance compared to the conventional chemical conversion method. It was also found that the positive electrode plate had a high degree of chemical formation and a high capacity could be obtained in the initial stage.

Effects of the Invention According to the chemical formation method of the present invention, it is possible to significantly improve the overcharging performance, which was weak in conventional chemical formation in a battery case, and it is also possible to reduce costs by simplifying the manufacturing process of sealed batteries. It is something.

BRIEF DESCRIPTION OF THE DRAWINGS The figure shows a change in capacity due to overcharging between a battery cell formed by the chemical formation method of the present invention and an electric oil B formed by the conventional chemical formation method. Name of agent: Patent attorney Toshio Nakao and one other person Constant electricity t (, qh+

Claims (1)

[Scope of Claims] (1) A method for forming a sealed lead-acid battery in which positive and negative electrode plates are isolated by a separator serving as an electrolyte absorbing and holding body, and in which the amount of electrolyte is limited to a small amount, which A first injection step of injecting a dilute sulfuric acid electrolyte of less than a predetermined concentration and liquid amount into the battery container containing the electrode plate group, and infiltrating the electrolyte into the electrode plate group;
A first chemical formation process in which a charging current is applied to form a chemical substance, and a second chemical formation process in which a preforming process is performed and a predetermined electrolyte amount and concentration are achieved at the end of the chemical formation process.
1. A method for forming an L-type lead-acid battery, comprising the steps of: (2) The method for forming a sealed lead-acid battery according to claim 1, wherein in the first forming step, the progress of forming the positive electrode plate in the electrode plate group is 160 parts or more. (3) The sealed lead-acid battery according to claim 1 or 2, wherein the amount of electrolyte injected in the first injection step is 30 to 70 g of the electrolyte at the end of chemical formation in terms of capacity ratio. (4) The electrolytic solution injected in the first injecting step has a lower concentration than the electrolytic solution injected in the second injecting step. Method for forming a sealed lead-acid battery according to any one of the above claims 0 (6) Claim 1, in which 0.1 to 6 weight of sodium sulfate or magnesium sulfate is added to the injected electrolyte in the first injecting step. ~The method for chemically forming a sealed storage battery according to any one of Items 4 to 4.