JPH0815075B2 - Method for forming sealed lead-acid battery - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a method for chemical conversion in a battery case of a sealed lead-acid battery in which the amount of electrolyte is limited and there is no free electrolyte.

2. Description of the Related Art In a sealed lead-acid battery, the negative electrode absorbs oxygen gas generated from the positive electrode during charging to prevent the electrolyte from decreasing. Therefore, the negative electrode is a gas layer (oxygen) 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 discharged at the same time as charging, and therefore the unformed electrode plate cannot be formed. for that reason,
Generally, in a sealed lead-acid battery, a chemical conversion process in which the positive electrode active material is changed to lead dioxide and the negative electrode active material is changed to lead is performed outside the battery case before the battery is assembled.

However, chemical conversion outside the battery case complicates the battery manufacturing process, such as requiring immediate drying treatment to prevent oxidative deterioration of the negative electrode active material, and further requiring charging for activation after battery assembly. The cost was high.

As a method of solving these problems, it has been proposed to form an electrode plate in a battery case.

That is, an electrode plate group consisting of an unformed positive electrode plate, a negative electrode plate, and a glass mat separator capable of holding and absorbing an electrolytic solution is housed in a battery case, and excess dilute sulfuric acid is allowed to overflow into the electrode plate group. In addition, it is a method of charging the electrolytic solution to a predetermined concentration and liquid amount when the formation is completed.

Problems that the Invention is to Solve The conventional configuration as described above can be applied to a battery that can accommodate a large amount of electrolytic solution, but cannot be applied to a battery that increases volumetric efficiency and overflows when a large amount of dilute sulfuric acid is added. Is.

The present invention makes it possible to perform battery case formation of a sealed lead-acid battery in which an excessive amount of electrolyte cannot be added by performing battery case formation by using unformed electrode plates for both the positive electrode and the negative electrode.

Means for Solving the Problem The present invention is to add a dilute sulfuric acid of a liquid amount which is less than a predetermined amount after completion of chemical conversion in a battery case accommodating an electrode plate group, and after charging, has a predetermined electrolytic liquid amount and concentration. In this way, the chemical conversion method is such that the liquid is replenished or the liquid is recharged after the liquid is replenished so as to obtain a predetermined liquid amount and concentration.

Action In such a chemical conversion method of the present invention, the following two actions are roughly performed.

(A) When the amount of liquid is relatively large Since the formation of the negative electrode plate having good charging efficiency is completed earlier than that of the positive electrode plate, the formation is completed while being surrounded by dilute sulfuric acid and absorbing less oxygen gas than the positive electrode plate. However, if the battery is charged further to form the positive electrode plate, the electrolytic solution is decomposed and reduced, and the amount of the electrolytic solution becomes less than a predetermined value, so that the capacity as a battery cannot be sufficiently obtained. In order to prevent this, it is only necessary to use a replenishing solution, which can be solved by adjusting the replenishing solution to a predetermined amount and concentration of the electrolytic solution.

(B) When the amount of liquid is small A battery with a small amount of liquid has good gas absorption, so oxygen is generated from the positive electrode plate and the negative electrode plate absorbs oxygen. Only formed in proportion. In this case, the capacity of the negative electrode plate is not sufficient because the formation of the negative electrode plate is not completed just by replenishing the liquid. However, by supplementing with more than the predetermined amount of electrolyte and charging, the negative electrode plate is surrounded by dilute sulfuric acid, oxygen gas absorption from the positive electrode plate disappears, and the discharge state is eliminated to complete the chemical conversion.

Example A specific example of a battery case formation method of a battery having a 10-hour rate capacity of 3 Ah in which an electrode plate group consisting of an unformed positive electrode plate, a negative electrode plate, and a glass mat separator that absorbs and holds an electrolytic solution is housed in a battery case is shown below. Describe. It has been confirmed that this battery discharges to the outside of the battery during charging if more than 29 ml of liquid is injected in advance.

After injecting 29 ml of dilute sulfuric acid with a concentration of 30% by weight into the battery case and opening a valve to prevent oxygen from entering the battery from outside, 40 at 0.3A
After charging for 3 hours, add 3 ml of dilute sulfuric acid having a concentration of 41.5 wt% and adjust the dilute sulfuric acid electrolyte to have a concentration of 41.5 wt% and a liquid volume of 27 ml. According to the chemical conversion method of the present invention, there are a battery (A) and a battery (B) manufactured by a chemical conversion method without replacement liquid.

Furthermore, assuming a battery with a small injection volume, add 26 ml of dilute sulfuric acid with a concentration of 28% by weight, and after opening the valve in the same manner as above, at 0.3 A
After charging for 40 hours, 4.5 ml of dilute sulfuric acid having a concentration of 41.5% by weight was added and further charged at 0.3 A for 5 hours to obtain the same predetermined concentration and liquid amount as described above. The battery (C) according to the present invention and the battery (D) which does not perform replenishing solution.

Next, the discharge capacity results of the batteries (A) and (C) by the chemical conversion method of the present invention and the batteries (B) and (D) by the conventional chemical conversion method are shown in the following table.

EFFECTS OF THE INVENTION According to the chemical conversion method of the present invention, a sealed lead-acid battery with extremely high capacity efficiency can be manufactured because it can be applied to a battery that cannot store a large amount of electrolyte, which was not possible by conventional chemical conversion in a battery case. The cost can be reduced by simplifying the process.

Claims (1)

[Claims] 1. A method for forming a sealed lead-acid battery in which positive and negative electrode plates are separated by a separator that serves as an absorber for an electrolytic solution and the amount of the electrolytic solution is limited to a small amount. In the tank, there is a liquid injection step of injecting a liquid amount that is less than a predetermined amount after completion of formation, a step of forming an electric current by flowing a charging current, and a replenishment process of making a predetermined electrolyte amount and concentration next, A method for forming a sealed lead-acid battery, in which charging is performed later to complete formation of the negative electrode plate.