JPH09139229A - Lead-acid battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To uniform the voltage characteristic and improve the life by increasing the filling density of positive electrode active material successively from low temperature part toward high temperature part. SOLUTION: Cells each formed of a positive electrode plate 1 consisting of antimony-free casted grid, a negative electrode plate 2 and a separator 3 consisting of fine glass fiber are connected in series within a PP resin battery jar 4 to constitute a sealed lead-acid battery. The filling density of positive electrode active material is increased for every cell successively from the cell having a positive electrode terminal toward the cell having the negative electrode plate while keeping electrolyte quantity constant. This change ratio is set to a ratio necessary to cancel the discharge capacity difference resulted from the temperature difference generated in each cell. Thus, the filling density of the positive electrode active material is increased every cell from low temperature part toward high temperature part, whereby the voltage characteristic in discharge is uniformed to improve the life performance of the battery.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an improvement of a lead storage battery.

[0002]

2. Description of the Related Art As a lead storage battery, it is common to use a single cell 2V battery or a 6V series connected 12V battery in series or in parallel. For example,
In recent years, 12V batteries have been used in sealed lead-acid batteries for electric vehicles.
A system for connecting four in series is being studied.
This 12V battery is a so-called s with 6 cells arranged in a line.
side-to-side type or c arranged in 2 × 3 columns
The combination type is the mainstream. Particularly, in an electric vehicle, these 12V batteries are mounted in a plurality of rows or stacked vertically depending on the shape of the vehicle body.

By the way, charging and discharging of this lead-acid battery is caused by a positive and negative electrode active material and an electrolytic solution (dilute sulfuric acid), and their weight ratio, volume ratio and composition are designed so as to be uniform at each site inside the cell. Has been done.

[0004]

However, in lead-acid batteries used in combination in series or in parallel, a plurality of lead-acid batteries are used.
When heat is generated internally by the discharge reaction, it is quickly cooled in the part with good heat dissipation, but in the part with poor heat dissipation, heat cannot be efficiently dissipated to the outside of the battery, so inside the cell or inside the 12V battery or between 12V batteries A temperature difference is generated.

In such a high temperature portion, the discharge capacity increases as compared with the low temperature portion due to the improvement of the utilization rate of the positive electrode active material.

Therefore, when constant power discharge is performed in a state where there is a temperature difference between the cells of a large number of batteries connected in series, the discharge current value and the discharge end voltage are determined by the total voltage of the whole group battery. In the cell of the low temperature part, which has a small discharge capacity, the cell is discharged to a region lower than the original cutoff voltage, and in some cases, it is poled to generate a large amount of gas and raise the temperature.

On the other hand, the repetition of this reversal not only deteriorates the charge / discharge performance of the cell, but also increases the internal resistance due to the dry-up of the electrolytic solution.

Therefore, an object of the present invention is to provide a lead-acid battery with a temperature difference in each cell and each battery when in use,
It is to make the voltage characteristics of each cell and each battery uniform during discharge, and to improve the life performance of a lead storage battery composed of a plurality of cells or a group battery or an assembled battery composed of a plurality of lead storage batteries.

[0009]

A lead-acid battery according to the first invention is a lead-acid battery which produces a temperature difference during charging and discharging,
As the battery is located from the low temperature part to the high temperature part,
The positive electrode active material has a high packing density.

The group battery or assembled battery according to the second invention is a group battery or assembled battery that causes a temperature difference during charging and discharging, and the battery is positive electrode active for each battery as it is located from the low temperature portion to the high temperature portion. It is characterized by a high packing density of the substance.

A third invention is the lead storage battery according to the first invention or the group battery or assembled battery according to the second invention, wherein the battery is arranged from the low temperature part to the high temperature part and It is characterized in that the packing density is large for each cell.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION A preferred embodiment of the present invention will be described in detail below.

FIG. 1 is a partial sectional view showing a 12V, 60Ah 6-cell sealed lead-acid battery according to the present invention.

In the figure, 1 is a positive electrode plate made of an antimony-free cast grid, 2 is a negative electrode plate made of an antimony-free cast grid, 3 is a separator made of fine glass fiber, 4 is a battery case made of PP resin, Reference numeral 5 is a lid, and 6 is a partition.

Each cell was composed of 10 positive electrode plates and 11 negative electrode plates, and the same negative electrode plate 2 was used.

With respect to the positive electrode plate 1, when the cell having the positive electrode terminal is the first cell and the cell having the negative electrode terminal is the sixth cell, the densities of the positive electrode active materials are 3. to 6 in order from the first cell to the sixth cell. 8, 3.9, 4.0, 4.0, 3.9,
And 3.8 g / cm ^3, standard density 3.9 g / cm ³
On the other hand, 0.97: 1: in order from the first cell to the sixth cell.
It was manufactured to have a ratio of 1.03: 1.03: 1: 0.97.

This density ratio is approximately equivalent to the ratio required to offset the difference in discharge capacity due to the temperature difference between cells in the charge / discharge cycle life test described below.

That is, when the density of the positive electrode active material is the same in each cell, the first in the following charge / discharge cycle life test is performed.
The discharge capacity ratio from cell to sixth cell is approximately 0.98: 1:
Since it corresponds to 1.02: 1.02: 1: 0.98, the discharge characteristics of each cell during the charge / discharge cycle life test can be made uniform by adjusting the density of the above positive electrode active material.

Since the weight of the positive electrode active material is constant,
The electrode plate thickness changes as the active material density increases and decreases.
All other elements were the same in each cell.

This battery was designated as Product A of the present invention, and for comparison, the densities of the positive electrode active materials were 3.85, 3.9, 3.95, 3.95, 3. 9,
Density of the present invention product B and positive electrode active material was 3.85 g / cm ³ were subjected to a charge-discharge cycle life test shown below using the conventional products all cells 3.9 g / cm ^3.

(Life test conditions) Discharge: Charging up to a final voltage of 8.4 V with an SFUDS79 pattern ... Charging up to 14.5 V at 30 A, and then charging at 6 A until the amount of electricity charged is 120% of the amount of electricity discharged Temperature ... 30 In a constant temperature bath at ℃ (capacity test condition) The following capacity test is performed every 50 times of the charge / discharge cycle. Discharge: Charged at a final voltage of 9.9V at 20A ... Charged at 14.5V at 30A, then charged at 6A until the amount of electricity charged is 120% of the amount of electricity discharged Temperature ... In a constant temperature bath at 30 ° C 2 shows. When the life is defined as the time when the number of SFUDS79 pattern discharges is halved, the battery A according to the present invention is
Has a life performance of about 1.7 times that of the conventional product, and Battery B has a life performance of about 1.5 times.

In this embodiment, the 12V sealed lead-acid batteries were individually tested, but the open-type lead-acid battery or the group battery of two or more batteries may be tested at the temperature during the test. Similar effects were observed when a difference was made. Here, the active material packing density of the positive electrode plate was changed for each cell, but the packing density may be changed for each electrode plate in each cell, or both for each cell and each electrode plate. Good.
Furthermore, in the case of the group battery, the active material density may be changed not only for each cell but also for each battery, or both may be combined. These combinations are free within the scope of the present invention, in which the positive electrode active material packing density is higher in the high temperature portion than in the low temperature portion.

In addition, each cell may be one for each cell, or may be one for every two cells or a plurality of cells. This may be set similarly for each electrode plate and each battery.

On the contrary, when a temperature difference occurs during the test even in a single-cell 2V battery, the reaction distribution is made uniform by the method according to the present invention, that is, by each electrode plate, so that the electrode plates connected in parallel are connected. The effect that the deterioration of the positive electrode active material of (1) progresses uniformly was also recognized.

Needless to say, the positive electrode active material of the present application means a positive electrode paste containing a binder.

[0026]

The lead-acid battery according to the first aspect of the present invention is a lead-acid battery that causes a temperature difference during charging and discharging, and the battery has a higher packing density of the positive electrode active material as it is located from the low temperature portion to the high temperature portion. Characterize.

The group battery or assembled battery according to the second invention is a group battery or assembled battery that causes a temperature difference during charging and discharging, and the battery is positive electrode active for each battery as it is located from the low temperature portion to the high temperature portion. It is characterized by a high packing density of the substance.

A third invention is the lead-acid battery according to the first invention or the group battery or assembled battery according to the second invention, wherein the battery is arranged from the low temperature part to the high temperature part and It is characterized in that the packing density is large for each cell.

As a result, when the lead storage battery is used, each cell,
Since the difference in discharge capacity caused by the temperature difference in each battery can be canceled out, the voltage characteristics during discharge of each cell and each battery are made uniform,
Therefore, it is possible to improve the life performance of a lead storage battery including a plurality of cells or a group battery or an assembled battery including a plurality of lead storage batteries. Its industrial value is enormous.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view of a lead storage battery according to the present invention.

FIG. 2 is a diagram showing a charge / discharge cycle life test result of a lead storage battery according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Positive electrode plate 2 Negative electrode plate 3 Fine glass fiber separator 4 Battery case 5 Lid 6 Partition 7 Positive electrode terminal

Claims (3)

[Claims] 1. A lead-acid battery which produces a temperature difference during charging and discharging, wherein the battery is located from a low temperature part to a high temperature part,
A lead storage battery having a high packing density of a positive electrode active material. 2. A group battery or assembled battery that causes a temperature difference during charging and discharging, wherein the battery is located from a low temperature portion to a high temperature portion,
A group battery or an assembled battery, wherein the packing density of the positive electrode active material is high for each battery. 3. The lead acid battery according to claim 1, or the group battery according to claim 2, wherein the battery has a higher packing density of the positive electrode active material in each cell as the battery is located from the low temperature portion to the high temperature portion. Batteries.