JPH0945364A - Sealed lead-acid battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a high efficiency discharge characteristic of a saled lead- acid battery, and improve a cycle service life characteristic. SOLUTION: When being inserted into a battery jar, the ratio C of a thickess of a separator in a drying condition pressurized under pressure of 20kg/dm<2> to a layering directional dimension of a plate which can be possessed by the separator and an average hole diameter D of the separator in a pressurizing condition are constituted so as to respectively fall within a range of (1.15<=C<=1.5) and (1<=D/C<=3).

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, and more particularly to the relationship between the average pore size of a separator and the compression ratio of the separator.

[0002]

2. Description of the Related Art In a sealed lead-acid battery, a positive electrode plate, a negative electrode plate and a plurality of separators are superposed on each other, and the electrode plate group is inserted into a battery case under a group pressure. It is configured by injecting an electrolytic solution into a battery case. BACKGROUND ART Conventionally, a glass fiber mat having good hydrophilicity has been used as a separator of a sealed lead acid battery. This separator is designed not only to hold the electrolytic solution inside the battery cell but also to distribute the electrolytic solution evenly over the entire upper and lower sides of the separator.

Generally, the discharge capacity of a sealed lead-acid battery is governed by the amount of electrolytic solution retained inside the cell chamber, and increases as the amount of electrolytic solution retained in the positive and negative electrode active materials and the separator increases. .

[0004]

However, the gravity of the electrolytic solution held in the separator of the sealed lead-acid battery causes a bias in the upper and lower parts of the separator. Furthermore, using a separator having a relatively large average pore diameter, and repeating the charge and discharge by holding a large amount of this electrolyte, the specific gravity difference generated in the electrolyte held in the separator is promoted, so-called electrolysis The stratification of the liquid becomes noticeable.

At this time, deep charging and discharging are repeated in the electrode plate portion contacting the lower portion of the separator holding the electrolytic solution having a high specific gravity, so that the active material is softened. This softened active material is likely to fall off the electrode plate, resulting in a reduction in the capacity of the lead storage battery and deterioration of the discharge characteristics. In the sealed lead-acid battery having such a difference in specific gravity of the electrolytic solution, the battery life is significantly deteriorated as the charging / discharging cycle progresses.

On the other hand, in order to improve the high rate discharge capability, it is necessary to maintain the group pressure of the electrode plate group in a high state. However, as the group pressure increases, the expansion force toward the outside of the battery case increases, and the battery container swells. Due to the expansion of the battery case, the commercial value of the sealed lead-acid battery is greatly reduced.

The present invention solves the above problems and provides a sealed lead-acid battery which can improve the high rate discharge characteristics of the battery and also the cycle life characteristics thereof.

[0008]

Means for Solving the Problems In order to solve the above problems, the present invention relates to a sealed lead acid battery in which an electrode plate group composed of a positive electrode plate, a negative electrode plate and a separator is inserted into a battery case in a dry state. When the electrode group is inserted into the battery case with, the size in the stacking direction of the electrode plates that can be occupied by the separator (A ) To the ratio (B / A) of the thickness (B) of the separator in the dry state pressurized with a pressure of 20 kg / dm ² (hereinafter referred to as the separator compression ratio (C)), and the separator in the above state. It is intended to focus on the relationship with the average pore diameter (D) of the above, and the electrode plate group configured such that these values are in the ranges of 1.15 ≦ C ≦ 1.5 and 1 ≦ D / C ≦ 3, respectively. It is characterized by being used.

[0009]

By increasing the compression ratio of the separator, that is, by increasing the contact area between the electrolytic solution and the fibers that form the separator, the holding capacity of the electrolytic solution is increased and the specific gravity of the electrolytic solution generated in the vertical direction of the separator is increased. The difference can be suppressed. At the same time, the repulsive force of the separator is also increased, which makes it possible to delay the softening of the positive electrode active material and prevent it from falling off. Furthermore, a sealed lead-acid battery excellent in high rate discharge performance can be obtained by adjusting the average pore diameter of the separator and the decrease of internal resistance due to the improvement of the adhesion between the electrode plate and the separator.

[0010]

An embodiment of the present invention will be described below.

Nominal voltage and capacity of 12V38AH (20H) with various compression ratios and average pore diameters of the separator.
R) A corresponding sealed lead-acid battery was prepared. As shown in (Table 1), the separator made of glass fibers has a compression ratio (C) of 1.10 to 1.50, and the separator has an average pore diameter (D) of 1.10 to 1.10 when no compression force is applied. 4.5
Battery A-Battery O which were variously changed in the range of 5
Ten types were prepared for each of the five types.

[0012]

[Table 1]

At this time, all the lead-acid batteries were prepared so that the positive and negative electrode plates had the same thickness, the cell chamber dimensions of the battery case and the amount of electrolyte were the same. Further, the separator compression ratio was adjusted within the above range by changing the thickness of the separator. On the other hand, as a conventional product, the compression ratio (C) and the average pore diameter (D) of the separator are 1.20 and 10.0, respectively.
And the ratio of the average pore size to the separator compression ratio (D
/ C) was set to 8.33, and the other structure was the same as that of this example to prepare a sealed lead-acid battery.

For these batteries A to O and conventional products, the environmental temperature was 25 ° C. and the discharge current was 1.0 CA (24
A), an initial capacity test was performed with a discharge end voltage of 9.6V. The result of this initial capacity test is shown in FIG.

From FIG. 1, the batteries A, B and C having the compression ratio of the separator of 1.10 have a smaller initial capacity than the other batteries having the compression ratio of 1.15 or more. In addition, these batteries not only have a small initial capacity, but also have poor adhesion between the separator and the electrode plate, resulting in a high internal resistance, which makes it impossible to obtain good high rate discharge characteristics.

On the other hand, the initial capacities of the batteries D, G, J, and M in which the ratio (D / C) of the average pore diameter to the compression ratio of the separator is 1 or less have almost the same compression ratio,
The above ratio is 1 or more, which is smaller than that of other batteries having almost the same capacity as conventional products. This is because the area of the pores of the separator in the state where the group pressure is applied is small, and the amount of the electrolytic solution held in the separator and capable of participating in the charge / discharge reaction is small.

Then, using these batteries, under a temperature environment of 25 ° C., a charging voltage of 14.7 V and a charging current of 0.
After charging for 12 hours under the condition of 4 CA (9.6 A),
Similar to the initial capacity test, a cycle life test was performed in which discharge was performed at a constant current equivalent to 1.0 CA (24 A) until the discharge end voltage reached 9.6 V. The life was defined when the discharge capacity decreased to 70% of the initial capacity. The results of this test are shown in FIG.

From FIG. 2, it can be seen that the batteries C, F, I, L, O having a (D / C) of 3 or more and the conventional products have a life of approximately 1/2 of the cycle number of other batteries having a small ratio. Has reached. After the test, these batteries were disassembled and analyzed, and it was found that the cause of deterioration of these batteries was due to stratification of the electrolytic solution.

On the other hand, when the compression ratio of the separator exceeds 1.5, the group pressure of the electrode plate group becomes high, which deteriorates the workability in constructing the battery and also causes the damage to the battery case. sell.

From the above results, in order to provide a sealed lead acid battery having an excellent cycle life without reducing the discharge capacity, the compression ratio (C) of the separator and the ratio of the average pore diameter to the compression ratio (D) of the separator (D). ) Need to form electrode plate groups in the ranges of 1.15 ≦ C ≦ 1.5 and 1 ≦ D / C ≦ 3, respectively.

[0021]

As described above, according to the present invention, the softening of the positive electrode active material, which is the main cause of the deterioration of the charge / discharge cycle, can be delayed, and at the same time, the positive electrode active material can be prevented from falling off and the cycle life characteristics can be improved. Can be greatly improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between a compression ratio of a separator and an initial capacity.

FIG. 2 is a diagram showing a relationship between a compression ratio of a separator and a life cycle number of a storage battery.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor ▲ Taka ▼ Ichitaro Ki, 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (1)

[Claims] 1. A positive electrode plate, a negative electrode plate and a separator.
The sealed lead-acid battery, which is made by inserting the assembled electrode plate into the battery case
The separator plate when it is dry and inserted into the battery case.
For the dimension (A) in the stacking direction of the electrode plates that the data can occupy
20 kg / dm ²Separation in the dry state pressurized with the pressure of
Separator pressure, which is the ratio (B / A) of the thickness (B) of the data
The reduction ratio (C) is in the range of 1.15 ≦ C ≦ 1.5, and
Separating the average pore diameter (D) of the separator in the above state
The ratio (D / C) to the rater compression ratio is 1 ≦ D / C ≦
Closed type characterized by using electrode plates in the range of 3
Lead acid battery.