JPS5920970A - Method for manufacturing lead storage battery - Google Patents

Abstract

PURPOSE:To prevent dilute sulfuric acid from splashing out of the battery case during the formation process within the battery case and thereby to easily control environmental pollution, by carrying out the formation for the electrode assembly arranged in a sealed battery case provided with a check valve which is adapted to be open when the pressure within the case exceeds a predetermined pressure value. CONSTITUTION:Paste-type anode plates and cathode plates which are not yet formed are arranged into an electrode assembly in such a way that 2 anode plates and 3 cathode plates are piled alternately via a glass mat separator, which remarkably soaks up liquid, inserted in between. And thus obtained electrode assembly is put in a plastic battery case to form an unit cell. Then, 12ml of sulfuric acid whose specific gravity being 1.20 is poured into each unit cell, and then each unit cell is provided with a rubber check valve which is adapted to be open when the internal pressure becomes higher than the atmosphere by 1/4 atmospheric pressure. Thereafter, the forming within the battery case is carried out with 100mA of electric current applied thereto for 90hr. Since the battery case is sealed from the atmosphere during the forming process, the metallic lead serving as the active material for the cathode, which is brought into a chemically active state during the formation, is prevented from being oxided by the air that would be drawn from the atmosphere into the battery and thus, an effective formation can be carried out.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for manufacturing lead-acid batteries, particularly sealed lead-acid batteries.

Conventional Structures and Problems Traditionally, lead-acid battery manufacturing methods include methods in which the electrode plates are chemically formed in a separate location before being incorporated into the battery case, and then incorporated into the case, and methods in which the electrode plates are formed without chemical conversion A method is known in which chemical conversion is performed after the battery is incorporated into a battery case. Here, so-called battery cell formation, in which chemical formation is carried out after the unformed electrode plates are assembled into a battery case, is not easy to carry out in cases where the electrolyte contains a large amount of dilute sulfuric acid, such as in lead-acid batteries for automobiles. However, if the amount of free-flowing dilute sulfuric acid is so small that it is virtually non-existent when the battery is completed, it is not possible to use exactly the same method as when the amount of dilute sulfuric acid is large.

For lead-acid batteries, the amount of dilute sulfuric acid is reduced to such an extent that there is virtually no flowing part when the battery is completed.The dense gas absorption method basically uses the cathode to absorb oxygen gas generated from the anode during overcharging. The feature is that almost no gas escapes to the outside of the battery. With this cathode gas absorption method, the cathode can always absorb oxygen gas, so if outside air can freely enter the battery, oxygen gas in the air will be continuously absorbed and the cathode will absorb oxygen gas. Therefore, if you want to reduce the amount of flowing electrolyte to the point where there is virtually no flowing electrolyte at the end of battery formation, it is necessary to perform so-called battery formation in which the inside and outside of the battery are open. It cannot be implemented as is.

OBJECTS OF THE INVENTION The present invention provides a manufacturing method that enables battery cell formation in such sealed lead-acid batteries. In a type of lead-acid battery in which almost all of the dilute sulfuric acid is retained in absorbed form in the positive and negative plates and separators, with virtually no free-flowing dilute sulfuric acid present, the plates are This device is characterized by being built into a sealed battery case that is equipped with a check valve that opens only when the pressure exceeds the pressure.

Description of examples Examples of the present invention will be described in detail below.

Using unformed paste type anode plates and cathode plates, two anode plates and three cathode plates are stacked alternately with a highly liquid-absorbing glass mat separator interposed in between to form an electrode plate group. The board group is assembled into a plastic battery case to form a single cell, and the nominal voltage of 3 single cells is 6 V, and the nominal capacity is i1.
．． A 2Ah (20HR capacity) battery is constructed.

Each cell was injected with 212me of dilute sulfuric acid with a specific gravity of 1.20, and a rubber tube was placed in each cell that opened when the pressure inside the cell reached 174 atm or more compared to atmospheric pressure. Install a check valve.

Next, in order to compare with this example, in the battery of the example,
A battery case was formed in the same manner as in the example using a battery configured without a rubber check valve.

After completion of chemical formation, the battery of this comparative example was fitted with a rubber check valve to seal the battery to prevent outside air from being drawn into the battery.

The batteries of the Examples and Comparative Examples described above are 6QlfiA.
When the battery was discharged at a current of 1,70 V until the cell voltage reached 1,70 V, the discharge duration was 21 hours for the example battery and 19 hours for the comparative example battery.

As is clear from the discharge results, the Example showed superior results compared to the Comparative Example.

This is because, in the battery of this example, outside air is sucked into the battery at a time when there is virtually no dilute sulfuric acid flowing freely inside the battery during or after battery formation, causing chemical damage. Compared to the case where metallic lead, which is the active material of the cathode in an active state, is not oxidized, in the battery of the comparative example, it flows freely into the battery during and after the formation of the battery. This is because when the dilute sulfuric acid is virtually no longer present, it is inhaled into the outside air battery and partially oxidizes the metallic lead, which is the active material of the cathode, which is in a chemically active state. It seems likely that this is not the case.

Another feature of the present invention is that since the battery case is sealed with a check valve made of com, the droplets of dilute sulfuric acid generated inside the battery during the formation of the battery case are actually exposed to the outside of the battery. Almost no waste is emitted. Therefore, the present invention has the advantage that the amount of dilute sulfuric acid held in each unit cell is stabilized at the end of battery formation, and environmental protection during battery formation is facilitated.

Another advantage of the present invention is that when stain tank chemical conversion is performed using the method of the present invention, water is decomposed by the chemical formation and flows out of the battery until the free flowing dilute sulfuric acid inside the battery is exhausted. Although it is smoothly discharged and removed, once the moisture in the battery decreases and free-flowing dilute sulfuric acid is virtually no longer present, the oxygen gas absorption reaction at the cathode proceeds efficiently, causing the oxygen gas generated from the anode to proceed efficiently. Oxygen gas is immediately absorbed by the cathode, suppressing the generation of hydrogen gas from the cathode, and making it difficult for further decomposition and reduction of water to occur.

Effects of the Invention As described above, the present invention enables efficient cell formation of sealed lead-acid batteries in which substantially no free electrolyte exists.

Claims (1)

[Claims] The unformed anode plate, cathode plate, and separator are placed in a sealed battery case equipped with a check valve that opens when the pressure exceeds a predetermined level, and a dilute sulfuric acid electrolyte is injected. A method for producing a lead-acid battery, characterized by removing free electrolyte from the inside of the battery case by performing chemical formation.