JP3221154B2 - Sealed lead-acid battery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealed lead-acid battery used, for example, for portable equipment, and more particularly to an improvement in a separator thereof.

[0002]

2. Description of the Related Art A lead storage battery has a higher energy density than other secondary batteries, and is inexpensive and excellent in economy. In particular, the demand for a sealed lead-acid battery as a power supply for a small electronic device such as a VTR and a backup power supply has recently increased, and the performance thereof has been remarkably improved.

[0003] There have been many proposals for improvements in sealed lead-acid batteries. A typical example is a so-called free electrolyte (free solution) in which the amount of the electrolyte is equal to or less than the pore volume (retention volume) of the electrode plate group including the positive electrode plate, the negative electrode plate, and the separator. A method is adopted in which the anode gas is absorbed and removed by the negative electrode plate at the end of charging to prevent a decrease in the amount of the electrolytic solution.

[0004] This sealed lead-acid battery has no free liquid, and therefore has the characteristics that it does not leak even if the battery is used upside down or even if it is turned over, and does not require water refilling. Used in the direction.

[0005] Such a sealed lead-acid battery separator is mainly composed of glass fibers having an average diameter of 1 µm or less, and is stacked together with a positive electrode plate and a negative electrode plate to form an electrode plate group in order to improve the liquid retention amount. The glass fiber density after being incorporated in the battery case is generally 0.15 to 0.20 g / cm ³ , and the porosity is generally about 93 to 94%.

[0006]

In such a structure of the electrode group, the separator has a high porosity and a large liquid retention amount, so that a high initial capacity can be obtained. However, since the glass fiber density is low, the adhesion to the electrode plate is not sufficient,
When the electrolytic solution evaporates from the surface of the battery case due to trickle charging at a high temperature or left for a long period of time and the amount of the electrolytic solution decreases, the electrolytic solution particularly in the separator decreases, and the adhesion pressure between the separator and the electrode plate greatly decreases.

For this reason, the contact area between the separator and the electrode plate is reduced, and the internal resistance of the battery is increased. Therefore, there is a problem that the capacity is reduced and the life is shortened.

The present invention solves such a problem, and prevents a decrease in the adhesion between the separator and the electrode plate and stabilizes the capacity even if the amount of the electrolytic solution is reduced, thereby achieving a long life sealing. It is an object of the present invention to provide a lead-acid battery.

[0009]

In order to solve such a problem, in the sealed lead-acid battery of the present invention, the glass fiber density of the separator after the electrode group is incorporated in the battery case is set to 0.1.
21 to 0.25 g / cm ³ .

[0010]

According to the sealed storage battery of the present invention, by increasing the glass fiber density of the separator of the electrode group,
Even if there is a decrease in the electrolyte during long-term storage or during trickle charging, a decrease in the capacity can be prevented, so that the life can be significantly extended as compared with the conventional case.

[0011]

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

The sealed lead-acid battery used in this embodiment has a width of 2
5 mm, height 45 mm, thickness 3.2 mm, two positive plates, three 1.8 mm negative plates, and only glass fiber without binder having an average fiber diameter of 0.8 μm. And an electrode group formed by alternately stacking separators having a glass fiber density of 0.15 g / cm ³ when pressurized at 20 kg / dm ² . These electrode plates were assembled in an ABS battery case, sealed with a lid, charged with a specified amount of dilute sulfuric acid as an electrolytic solution, charged, and charged to a rated capacity of 12.
A sealed lead-acid battery of V2.0 Ah was prepared.

The positive electrode plate and the negative electrode plate of this battery are selected and used so that the average electrode plate thickness is within ± 0.02 mm.
As the separator, five types having different thicknesses were used, and the glass fiber density after being incorporated in the battery case was 0.15 g / cm.
³ , 0.18 g / cm ³ , 0.21 g / cm ³ , 0.2
4 g / cm ³ and 0.27 g / cm ³ , porosity 89
Adjusted to be ~ 94%.

The five types of batteries created in this way are:
After charging and measuring the initial capacity, the battery was subjected to a trickle life test in which the battery was charged at a constant voltage of 13.8 V at 40 ° C., and the capacity was measured every two months.

In the capacity test, discharge was performed at 2.0 A.
The time until the voltage dropped to 0 V was measured.

FIG. 1 shows the characteristics of the distribution of the glass fiber density and the initial capacity of the separator. Also, FIG.
The characteristics of the capacity, the initial ratio of the internal resistance, and the amount of liquid reduction when the trickle life test was performed at ℃ were shown for each glass fiber density of the separator.

When the glass fiber density of the separator increases, the porosity decreases by 2 to 3% as compared with the prior art, so that the liquid holding amount of the separator decreases, and the initial capacity decreases slightly.

The trickle life characteristic at 40 ° C. is such that the conventional separator having a glass fiber density of 0.15 to 0.20 g / cm ³ has a life of 5 to 10 months because the capacity becomes 50% or less of the initial value. However, the life of the separator having a glass fiber density of 0.21 to 0.27 g / cm ³ was extended to about 13 to 20 months. The amount of battery reduction during trickle charge is
It increases in proportion to the trickle charge period regardless of the glass fiber density of the separator. It can be seen that the internal resistance of the battery is increased by this liquid reduction, but the internal resistance of the battery having a lower glass fiber density increases rapidly with a small amount of liquid reduction, and the capacity decreases promptly.

From these results, it was found that the glass fiber density of the separator was increased from the conventional 0.15 to 0.20 g / cm ³ to 0.21 g / cm ^3.
When it is increased to 〜0.27 g / cm ³ , the initial capacity is slightly reduced, but the life in trickle charge can be extended to two to three times.

The same effect can be expected in preventing the recovery capacity from decreasing due to the decrease in the electrolyte during long-term storage.

However, when the glass fiber density of the separator is 0.27 g / cm ³ , the pressing force when the electrode group is incorporated into the battery case becomes 100 kg / dm ² or more. Is easily deformed,
Practically, the upper limit is about 0.25 g / cm ³ .

As is clear from the above description of the embodiment, according to the sealed lead-acid battery of the present invention, the initial capacity is slightly reduced as compared with the conventional battery, but the trickle life is increased.
Since the battery is extended two to three times, a battery having a long life and high reliability can be obtained.

The following can be considered as a reason for this.

When the glass fiber density of the separator is increased, the liquid holding amount of the separator is also reduced due to the decrease in the porosity, so that the initial capacity is slightly reduced. However, since the adhesion pressure between the separator and the electrode plate is improved, even if the electrolyte decreases due to trickle charging or the like (particularly, the electrolyte in the separator),
Since the decrease in the contact area between the separator and the electrode plate is small, it is considered that the increase in the internal resistance of the battery can be prevented and the life can be extended.

[0025]

As described above, according to the present invention, by improving the glass fiber density of the separator of the electrode group,
The capacity recovery after a long-term storage, the trickle life characteristic, etc. can be greatly improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing glass fiber density and initial capacity characteristics of a separator of a sealed lead-acid battery according to one embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a trickle period, a capacity, an internal resistance, and a liquid reduction amount of the battery.

Claims (1)

(57) [Claims] 1. A positive electrode plate, a negative electrode plate, and an average fiber diameter of 1 μm.
m in a sealed lead-acid battery in which an electrode group consisting of a separator substantially composed of only glass fibers of not more than m is incorporated in a battery case, the glass fiber density of the separator in the battery case is 0.21 to 0.25 g. / Cm ^3, which is a sealed lead-acid battery.