JPH04345757A - Manufacture of closed type lead battery - Google Patents

Abstract

PURPOSE:To reduce self-discharge quantity during the long time leaving of a battery and improve a capacity restoring property by making supplemental charge after battery voltage is over-discharged to 0.5 V/cell or less after finishing initial charge or battery jar formation. CONSTITUTION:Batteries of 6V 2.0Ah are made by forming a positive plate, using 1% Pb-CaO-8% SnO to which Sn is added as a positive electrode grid alloy, together with a negative plate in a plate condition, then putting a plate group, composed of separators consisting of the positive plate, the negative plate, and glass fiber, in a battery jar to be sealed, and making a battery, initially charged by injecting dilute sulfuric acid as an electrolyte, three-cell- series constitution. This battery is over-discharged to a battery voltage of 0.5V/ cell or less, and then is supplementally charged.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a sealed lead-acid battery, and more particularly to a method of manufacturing a sealed lead-acid battery with an improved charging method.

0002

BACKGROUND OF THE INVENTION Lead-acid batteries have a higher energy density and are more economical than other batteries. In particular, the demand for sealed lead-acid batteries for use in small electronic devices such as video tape recorders has increased recently, and their performance has been significantly improved.

[0003] Many proposals have been made regarding sealed lead-acid batteries. As a typical example, the amount of electrolyte is set to be equal to or less than the pore volume of the electrode plate group consisting of the positive electrode plate, negative electrode plate, and separator, so-called free liquid (
A method is adopted in which the oxygen gas generated from the positive electrode plate is absorbed by the negative electrode plate at the end of charging to suppress the decrease in the electrolyte amount.

[0004] Sealed lead-acid batteries are used in a wide variety of applications because they do not have free electrolyte, so they do not leak when laid down or upside down, and do not require water replenishment. .

[0005] Charging of such a sealed lead-acid battery is carried out by first charging after injecting an electrolyte into the electrode plates when chemically formed positive and negative electrode plates are used, or by performing an initial charge after injecting electrolyte into the electrode plates, or when using non-formed electrode plates. A common method is to perform battery cell formation after injecting an electrolyte.

[0006] After this initial charging or formation of the container, the battery is discharged a certain amount, and a capacity test is performed to measure the discharge voltage, and an auxiliary charge is performed to charge the discharged amount for the capacity test, and then the product is shipped.

[0007]

[Problems to be Solved by the Invention] However, in sealed lead-acid batteries shipped in such a state, a large amount of unstable lead dioxide (mainly α-PbO2) is present in the positive electrode plate, and most of it is In the initial stage of storage, the battery decomposes and forms coarse lead sulfate crystals that are difficult to charge, resulting in a large amount of self-discharge and a large capacity drop.

These coarse lead sulfate crystals become stable lead dioxide (β-PbO2) if they are recharged in the presence of a sufficient low-density (low-concentration) electrolyte, and even if they are left unattended again, lead dioxide remains. However, in sealed lead-acid batteries, which limit the amount of electrolyte with a high-density electrolyte, it is difficult to charge, especially in the commonly used constant-voltage charging method. Since the charging current is limited by the state of charge of the negative plate, which has less self-discharge compared to the negative plate, the positive plate becomes undercharged, and unless it is charged for a long time or overcharged with a constant current, it will There was a problem that the battery capacity did not recover.

[0009] The present invention solves the above problems.
An object of the present invention is to provide a method for manufacturing a sealed lead-acid battery that reduces self-discharge during long-term storage and improves capacity recovery.

0010

[Means for Solving the Problems] In order to solve the above problems, the method for manufacturing a sealed lead-acid battery of the present invention includes overdischarging until the battery voltage reaches 0.5 V/cell or less after initial charging or completion of battery cell formation. After that, you will need to re-charge the battery.

[0011]

[Function] In the method for manufacturing a sealed lead-acid battery of the present invention,
By over-discharging a sealed lead-acid battery after initial charging or after completion of battery cell formation, unstable lead dioxide (mainly α
-PbO2) is completely discharged and then re-charged, the unstable lead dioxide in the positive electrode plate is changed to stable lead dioxide (β-PbO2).

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS A method of manufacturing a sealed lead-acid battery according to an embodiment of the present invention will be described below with reference to the drawings.

[0013] The sealed lead-acid battery used in the test had a positive electrode plate using Pb-Ca0.1%-Sn0.8% to which Sn was added to improve charge acceptance after overdischarge as the positive electrode grid alloy. After chemical formation in the plate state along with the negative electrode plate, the electrode group consisting of one positive electrode plate, one negative electrode plate, and a separator made of glass fiber is placed in a battery container and sealed, and diluted sulfuric acid as an electrolyte is injected for initial charging. A 6V2.0Ah battery was created and used by configuring three cells in series.

Although not shown, the battery case of this battery has a frame made of polyethylene (PE) surrounding the electrode plate group,
Both sides of the electrode plate group are held down by a current collector plate made by laminating polyethylene film (hereinafter abbreviated as PE film) and tin plate, and the frame body and the PE film side of the current collector plate are sealed by heat welding, instead of conventional styrene. , acrylonitrile, and butadiene copolymer resin batteries (hereinafter referred to as ABS resin batteries), the water permeability is 1/10 or less, and the electrolyte solution hardly decreases during long-term storage.

Next, the initially charged battery was charged with an initial discharge current of 0.5A using a 12Ω resistor, and the final discharge voltage was 0.05.
Batteries for evaluation were prepared by discharging the batteries until they reached seven specified values between V/cell and 1.7 V/cell, and supplementary charging at 130% of the discharge amount.

[0016] The battery that has been overdischarged in this way is
After storing it at ℃ for 6 months, the remaining capacity rate (%) with the initial capacity as 100 and the recovered capacity rate (%) with the initial capacity after constant voltage charging at 2.45V/cell as 100 were measured. Changes in characteristics were compared.

As shown in Figure 2, batteries that are left for a long period after being subjected to normal discharge (end-of-discharge voltage 1.5 to 1.7 V/cell) without over-discharging show a large capacity drop and large capacity variations after being left unused. , and capacity recovery is also poor.

Even after charging, coarse lead sulfate crystals remained on the surface of the positive electrode plate of this battery.

However, below the flat region (hereinafter referred to as plateau) of the discharge pressure characteristics as shown in FIG. 1 (0.5 V/cell)
Batteries that are over-discharged until the end-of-discharge voltage decreases have less capacity loss and variation after long-term storage, as shown in A in Figure 2, and improved capacity recovery, as shown in B in Figure 2. , the effect is small in overdischarge where the end-of-discharge voltage is 1.0 V/cell or more, and the end-of-discharge voltage is at least 1.0 V.
It is desirable to overdischarge to a voltage of 0.5V/cell or less, preferably 0.5V/cell or less. This indicates that the plateau in the discharge pressure characteristics is thought to be due to a reaction in which α-PbO2 is discharged and becomes PbSO4, and it is assumed that this PbSO4 is changed to stable β-PbO2 by supplementary charging after overdischarge. Ru. Although this test only describes batteries using chemically formed plates, it was confirmed that similar effects were obtained with batteries formed using chemically formed containers, and there was no deterioration in characteristics such as cycle life and trickle life. There is.

[0020] Such overdischarge can be carried out continuously after a normal capacity test, so it can be easily carried out during the manufacturing process.

[0021]

[Effects of the Invention] As is clear from the above description of the embodiments,
A battery manufactured by the method for manufacturing a sealed lead-acid battery of the present invention has less capacity loss and less variation even when left for a long period of time, and has excellent capacity recovery.

The reason for this can be considered as follows. The positive electrode active material lead dioxide produced after initial charging or cell formation contains a lot of α-PbO2, which is unstable and easily decomposed.
- When PbO2 gradually decomposes in a high-density electrolyte, coarse and inactive lead sulfate crystals are formed, and PbO2 remains active even after charging.
Since it is difficult to return to 2, the remaining capacity and recovery capacity decrease after being left unused for a long period of time. Therefore, before leaving it for a long period of time, over-discharge is performed to discharge all α-PbO2 into fine, active lead sulfate that is easily charged, and then supplementary charging is performed to stabilize β-PbO2.
By converting to PbO2, the amount of self-discharge during long-term storage is reduced. This is thought to improve the recovery capacity rate because coarse lead sulfate crystals that are difficult to charge are not generated. Note that if the positive electrode lattice alloy does not contain Sn, a film of nonconducting lead sulfate will form on the lattice surface during overdischarge, resulting in poor charge acceptance. , Sn must be contained.

As described above, the battery manufactured by the method for manufacturing a sealed lead-acid battery of the present invention has reliability in capacity recovery even after being left unused for a long period of time by performing supplementary charging after initial charging and over-discharging. Therefore, its industrial value is extremely high.

[Brief explanation of the drawing]

FIG. 1 is a graph showing voltage characteristics during overdischarge in the manufacturing method of a sealed lead-acid battery according to an embodiment of the present invention.

[Figure 2] Figure 1
When the overdischarge shown in is
A graph showing the remaining capacity rate and recovered capacity rate when a battery is left for a long period of time after supplementary charging at a value specified in seven levels within the cell range.

Claims (2)

[Claims] Claim 1: An electrolytic solution is held in a positive electrode plate, a negative electrode plate, and a separator, and the amount of electrolytic solution is limited to such an extent that there is no free solution,
A method for manufacturing a sealed lead-acid battery in which the positive electrode grid alloy does not contain antimony but contains tin, and the battery is over-discharged after initial charging or completion of battery cell formation, and then supplementary charging is performed. 2. The method for manufacturing a sealed lead-acid battery according to claim 1, wherein supplementary charging is performed after over-discharging until the battery voltage reaches 0.5 V/cell or less.