JPH10106613A - Sealed lead-acid battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the discharging effect of a concentration cell on the edges of plates so as to enhance life performance during undercharging by specifying, relative to the total amount of electrolyte, the amount of electrolyte in the portion of a separator whose surface does not make contact with the plates. SOLUTION: A group of plates comprises a flat-paste positive plate 1, a negative plate 2 of the same size as the positive plate 1, and a separator 3 being greater than the positive and negative plates 1, 2 and sandwiched between the plates 1, 2. The separator 3 comprises a portion 3a whose surface makes contact with the plates and a portion 3b which does not, the surface of the portion 3b not making contact with the plates 1, 2 at three parts, i.e., the right and left sides and the upper side. An epoxy resin for reducing an impregnating electrolyte is applied to the portion 3b to impregnate the portion 3b with the resin. The amount of electrolyte in the portion 3b is less than 10% of the total amount of electrolyte present in the separator 3. Therefore, capacity degradation due to an undercharging cycle is small, and the amount of lead sulfate accumulated at the edge of the negative plate 2 also becomes smaller.

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 a separator in which an electrolytic solution mainly comprises an electrode plate and a glass mat or a porous material of an organic material or a mixed porous material of a glass fiber and an organic fiber. The present invention relates to a so-called retainer-type sealed lead-acid battery held by a battery.

[0002]

2. Description of the Related Art In recent years, a sealed lead-acid battery, which has been increasingly used for frequent discharging and charging, has been required to increase the energy density and the life performance, especially the undercharging. It is an urgent task to improve the life performance under the conditions (under the condition that the battery is likely to be almost charged). By the way, in a sealed lead-acid battery using a so-called oxygen cycle in which oxygen gas generated during charging of a battery is absorbed by a negative electrode, a method called a retainer type is currently in use. The term "retainer type" refers to a mat-shaped separator in which fine glass fibers or organic fibers inserted between a positive electrode plate and a negative electrode plate, or a mixture thereof, or an inorganic or organic porous material is used instead of these. In this method, a sulfuric acid electrolytic solution necessary for charging and discharging the battery is retained and the electrodes are separated.

[0003]

This separator is usually formed so as to protrude more than 3 mm from the size of the electrode plate so as to completely separate the two electrodes and prevent a short circuit.
It consists of a portion that comes into contact with the positive and negative electrode plates and side edges that protrude from these electrode plates. When such a sealed sealed lead-acid battery is discharged, the electrolyte retained in the portion protruding from the electrode plate has a lower utilization rate than the electrolyte retained in the portion in contact with the electrode plate, and between the two. Causes a difference in the concentration of the electrolytic solution.

[0004] When such a concentration difference occurs, a concentration cell is formed outside and inside the periphery of the electrode plate, and local charging and discharging are performed. At the periphery of the electrode plate where the discharge reaction has occurred, a larger amount of lead sulfate crystals are generated than at the center, the number of conductive paths is reduced, and the charging efficiency is reduced. When this is accumulated, the crystals of lead sulfate become coarse. Further, there is a problem that the battery capacity is reduced as soon as the undercharge cycle is continued in such a state.

The present invention has been made in view of the above problems, and an object of the present invention is to suppress the generation of lead sulfate and the decrease in the number of conductive paths due to the discharge of the peripheral portion of the electrode plate, and to reduce the lifetime. An object of the present invention is to provide a sealed lead-acid battery having excellent performance.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a hermetically sealed battery in which a positive electrode plate and a negative electrode plate are laminated via a flat separator to hold an electrolyte in an electrode group. A lead-acid battery, wherein the amount of electrolyte in a portion of the separator not in contact with the electrode plate is less than 10% of the total amount of electrolyte present in the separator. Things.

[0007]

The amount of the electrolytic solution not in contact with the electrode plate of the separator is 10% of the total amount of the electrolytic solution present in the separator.
By setting the concentration to less than that, the difference in the concentration of the electrolytic solution between the outside and the inside of the electrode plate around the periphery becomes small, and crystal formation of lead sulfate at the periphery of the electrode plate where a discharge reaction easily occurs, coarsening and the conduction path The reduction can be reduced and the life under the undercharge condition can be extended.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to the drawings. (Embodiment 1) FIG. 1 is a sectional view showing an embodiment of the present invention, and FIG. 2 is a longitudinal sectional view showing the pole group of FIG.
Is a positive electrode plate, 2 is a negative electrode plate, 3 is a separator, 4 is a battery case,
Denotes a positive electrode strap, 6 denotes a negative electrode strap, 7 denotes a positive electrode terminal, 8 denotes a negative electrode terminal, and 9 denotes a safety valve.

The positive electrode plate 1 is a flat paste-type electrode plate having a width of 108 mm and a height of 133 mm. The negative electrode plate 2 is a paste type electrode plate having the same size as the positive electrode plate 1. The separator 3 is made of a flat fine glass mat and is larger than the positive electrode plate 1 and the negative electrode plate 2 and has a width of 116.
mm and the height is 137 mm. A pole group is formed by sandwiching the separator 3 between the positive electrode plate 1 and the negative electrode plate 2. The separator 3 comprises a portion sandwiched between the plates 1 and 2, that is, a portion 3a in contact with the plates, and a portion not sandwiched between the plates 1 and 2, that is, a portion 3b not in contact with the plates. In this embodiment, the part 3 not in contact with the electrode plate
b is located at the left and right sides and at the upper three places, and an epoxy resin was impregnated and applied to these portions to reduce the amount of the impregnated electrolyte.

[0010] The electrode group having the above configuration is housed in the battery case 4,
The positive electrode plates 1 and the negative electrode plates 2 are connected by straps 5 and 6, and a positive electrode terminal 7 and a negative electrode terminal 8 stand from the straps 5 and 6, respectively. The electrode group contains a dilute sulfuric acid electrolyte having a specific gravity of 1.32 d.
The value is set as far as possible without the electrolyte flowing inside.
A sealed lead-acid battery A having such a nominal capacity of 35 Ah / 3HR was manufactured.

(Embodiment 2) In Embodiment 1, the portion 3b of the separator 3 not in contact with the pole plates 1 and 2, that is, one half from the outside of the left and right sides and the upper three portions is removed. Then, a battery B in which an epoxy resin was impregnated and applied to reduce the amount of the impregnated electrolytic solution was produced.

(Comparative Embodiment 1) Similarly, in the first embodiment, an epoxy-based resin was used to reduce the amount of the impregnated electrolyte in a quarter of the outside of the portion 3b of the separator 3 not in contact with the plates 1 and 2. Battery C coated with resin was prepared.

(Comparative Embodiment 2) Further, in Embodiment 1, no treatment is applied to the portion 3b of the separator 3 not in contact with the plates 1 and 2, and the separator 3 is in the same state as the portion 3a in contact with the plates 1 and 2. Battery D was prepared.

The plates 1, 2 of the separator 3 of each battery
As a result of examining the amount of the electrolyte contained in the portion 3b not in contact with the battery, the amount of the battery A with respect to the total amount of the electrolyte present in the separator was determined.
1%, battery B 5%, battery C 10%, battery D 12
%Met.

Next, the batteries A to D were subjected to an undercharge test. What is an undercharge cycle test? 25
(1) to (4) shown below are repeated at room temperature. (1) Discharge until the rated capacity reaches 80% of the rated capacity at a 3-hour rate current. (2) Leave for 6 hours. (3) The battery is charged with a current of 0.01 C (C indicates the value of the rated capacity) until the voltage becomes 2.4 V / cell. (4) Leave for 6 hours.

A 3 HR capacity test was performed every 10 cycles of the undercharge test, and then 115% of each capacity was charged at a current of 0.05 C. What is the 3HR capacity test?
1.65V cut-off voltage at 1 / 3C current at 25 ° C battery temperature
/ Discharge to the cell.

FIG. 1 shows the results of the capacity test every 50 cycles during the undercharge test. The discharge time in FIG. 1 is represented by setting the initial value of the battery A to 100. In addition, the amount of lead sulfate was examined for the active material 1 cm at the periphery of the negative electrode plate after 100 cycles of each battery. Table 1 shows the results.

[0018]

[Table 1]

From FIG. 1 and Table 1, it can be seen that the batteries A and B of the present invention have less capacity deterioration due to the under-charge cycle than the comparative battery C and the conventional battery D, and lead sulfate accumulated on the periphery of the negative electrode plate. The amount was also found to be small.

In this embodiment, epoxy resin is impregnated and applied to the portion 3b of the separator 3 which is not in contact with the electrode plate in order to reduce the amount of the electrolytic solution. However, another acid resistant resin is welded. Or may be impregnated. Examples of applicable acid resistant resins include thermoplastic resins (polyethylene, polystyrene, polypropylene, polyester, etc.) and thermosetting resins (phenol, formaldehyde, etc.).

When the material of the separator is an organic fiber of a thermoplastic resin or a mat-like porous body obtained by blending these with a glass fiber, the portion 3b may be melted by heat. All of the above methods reduce the porosity of the separator. However, while maintaining the porosity, a thin coating of a fluorine-containing resin such as a Teflon resin, a silicon resin, or the like is imparted with water repellency, thereby providing an electrolytic solution. Even if the liquid is not contained, the same effect as that of the embodiment can be obtained. Since the present invention is only to reduce the amount of the electrolytic solution impregnated in a portion of the separator as a so-called retainer that is not in contact with the electrode plate, the shape of the peripheral portion of the separator is not limited.

[0022]

As described above in detail, in the sealed lead-acid battery according to the present invention, the amount of the electrolyte not in contact with the electrode plate of the separator is reduced by the total amount of the electrolyte present in the separator. Since the amount is less than 10% of the amount, the influence of the discharge by the concentration cell at the peripheral portion of the electrode plate is reduced, and excellent life performance can be realized under the condition of undercharge.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view showing the pole group of FIG.

FIG. 3 is a graph showing capacity characteristics of batteries A to D in an undercharge test.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Positive electrode plate 2 Negative electrode plate 3 Separator 3a Portion which contacts an electrode plate 3b Portion which does not contact an electrode plate

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yasuhide Nakayama 6-6 Josai-cho, Takatsuki-shi, Osaka Inside Yuasa Corporation

Claims (1)

[Claims] 1. A sealed lead-acid battery in which an electrolyte is held in a group of electrodes formed by laminating a positive electrode plate and a negative electrode plate via a plate-like separator, wherein the separator is in contact with the electrode plate. A sealed lead-acid battery characterized in that the amount of electrolyte present in the unexposed portion is less than 10% of the total amount of electrolyte present in the separator.