JP2001223013A - Lead-acid battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve life property that the corrosion of positive electrode lattice body becomes the cause of the degradation in a lead-acid battery. SOLUTION: In the lattice body for lead-acid battery, compared with the mass per unit area of the upper cell in the neighborhood of the current collection ear part, lead-acid battery having the lattice body is made to have the mass per unit area of central part cell successively following the upper cell is made as the same mass or made heavier step-by-step or sequentially, and the mass per unit area of the lower cell is made lighter step-by-step or sequentially, compared with the mass per unit area of the central part cell. By this, reduction of battery performance, which is caused by the lattice body corrosion which is an important problem for the lead-acid battery is restrained, and the life property of batteries No.3, No.4 of the embodiment is improved compared with batteries No.1, No.2 of a conventional example.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lead-acid battery, and more particularly to a lead-acid battery requiring a stable battery life irrespective of environmental temperature.

[0002]

2. Description of the Related Art Lead-acid batteries are used for cycle applications in which charging and discharging are repeated, and for trickle applications and automobile applications where overcharging is the main problem. In all of these applications, corrosion of the positive electrode grid is a major cause of deterioration. One of them.

[0003] The lattice body is composed of a collecting ear part, a relatively thick shoulder bone, and a grid part occupying most of the grid part, and the grid part is formed by the grid bone and the intersection. As the corrosion progresses, the conductivity of the lattice decreases due to the change of the lead alloy into lead oxide having low conductivity, and elongation occurs at each portion. There has been a problem that the substance retention function is reduced and battery performance is reduced.

In order to prevent this, the corrosion resistance is improved by improving the composition of the lattice alloy, the lattice shape which suppresses elongation even when corroded, and the current collecting ear which is considered to have a large current density and to be easily corroded. By making the grid bone near the part thicker than the grid bones of other parts, improving the drop in voltage characteristics during efficient discharge and improving the grid body shape such as securing the grid bone cross-sectional area even when corrosion progresses It has been proposed to suppress a decrease in battery performance.

[0005]

However, in the conventional configuration, a temperature distribution occurs on the electrode plate, and local corrosion occurs. This local corrosion is remarkable when the environmental temperature is high.In the central part of the electrode plate, where heat is less likely to be radiated and the temperature rises more easily than the upper part of the electrode plate, which was conventionally considered to have a large current density and great corrosion. Corrosion was getting bigger. For this reason, the current path is cut off at the center of the electrode plate, and the battery characteristics deteriorate early even though the deterioration of the other portions is small, which is the service life of the battery.

[0006] In addition, as the performance of the equipment used increases, the batteries are required to be compact and the load is increased. In particular, many batteries are installed in a limited space especially for electric vehicles which are being developed recently. In addition to this, high rates of discharge and charging are performed, so that the temperature tends to be high, and improvement of the high temperature durability of the battery as well as the method of cooling the battery are important issues.

An object of the present invention is to solve such a conventional problem, and an object of the present invention is to provide a lead storage battery having excellent life characteristics regardless of the environmental temperature.

[0008]

Means for Solving the Problems In order to achieve the above object, the present invention relates to a grid for a lead-acid battery, in which the mass per unit area of the upper square near the current collecting ear is reduced.
Either the mass per unit area of the central square following the upper square is the same, or the weight is further increased toward the center of the lattice, and compared to the mass per unit area of the central square. Thus, the lead storage battery is provided with a lattice body configured to reduce the mass per unit area of the lower cell.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG.

The production of the electrode plate uses a method in which a cut is made in a strip-shaped sheet material obtained by rolling a lead alloy, developed, and a paste-like active material is continuously applied to the expanded lattice body 1 forming a grid. Was. For the expanding method, a reciprocating method was used in which the mold cutter moved up and down to cut the band-shaped sheet and unfolded at the same time. At this time, the overall mass of the positive electrode grid is the same, and the grid is moved from the upper part close to the current collecting ear part 2 to the lower part as shown in FIG.
Several types of lattices were prepared by dividing the lattice into parts and changing the lattice bone thickness to change the mass of each part. Here, as a conventional example, a battery having a uniform mass in each part is referred to as No. 1. No. 1, a battery in which the mass of the portion A which is the upper part of the lattice was made heavier than the other portions B and C in order to improve the current collecting function was No. 1. 2,
As an example of the present invention, a battery having a uniform mass from part A at the upper part of the lattice body to part B at the center, reducing the mass of part C at the lower part, and increasing the mass from part A to part B is described in No.
No. 3, the battery in which part B, which is the central part of the lattice body, was heavier than parts A and C was designated as No. 3. And 4. Table 1 shows the mass ratio of each part of these lattices.

[0011]

[Table 1]

The paste-like active material is prepared by adding water and sulfuric acid to a powder containing lead oxide as a main component and kneading the same, applying the same mass of active material to the lattice, aging and drying. An electrode plate was produced. After forming a group using six positive electrodes and seven negative electrodes of these electrode plates, a battery having a rating of 12 V and 30 Ah in which six cells were connected in series was produced. The thickness of the lattice bone is changed in each of the portions A, B, and C. The portions A, B, and C may be changed stepwise, or may be changed not stepwise but sequentially. This is also included in the embodiment of the present invention.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The lead-acid batteries (No. 3 and No. 4) of the present invention and the lead-acid battery (No.
1, No. 2) was evaluated by a 3CA discharge cycle life test at an environment temperature of 60 ° C. In addition, it is known that when this evaluation is performed on a conventional lead-acid battery, the service life is extended due to corrosion of the grid of the positive electrode. In this cycle life test, a process in which the battery was discharged to 8.4 V at a constant current of 3 CA and then charged by two-stage constant current charging was defined as one cycle. The two-stage constant-current charging referred to here is the first-stage current (0.2 CA) at 1
4.4V, and then the second stage charging current (0.0
5CA) for 4 hours.

FIG. 2 shows the relationship between the 3C discharge cycle life characteristics at 50 ° C. and the battery type. From FIG. 2, as compared with the thickness of the upper lattice bone near the collecting ear, the thickness of the subsequent lattice bone is made the same at the center of the lattice body, or as it goes toward the center of the lattice body. The battery No. of the embodiment of the present invention in which the thickness of the lower lattice bone is gradually reduced as compared with the thickness of the lattice bone at the center of the lattice body is further increased. 3, No. 4
Is the battery No. of the conventional example. 1 and No. It can be seen that the discharge capacity is larger than that of No. 2 and the life characteristics are excellent.

The battery No. Sample No. 1 was disassembled, the active material and the corroded layer were removed from the electrode plate, and the weight was measured to determine the amount of corrosion of the squares A, B, and C. At this time, the corrosion amount was determined according to the following equation.

(Amount of corrosion) = ((initial weight) − (weight after decomposition)) / (initial weight) × 100 As a result, B (52% corrosion)> A (45% corrosion)> C
The corrosion progressed in the order of (42% corrosion), and it was confirmed that the corrosion progressed toward the center of the electrode plate as shown in FIG.

From the above results, in the lead-acid battery, the thickness of the lattice bone of the positive electrode lattice body is compared with the thickness T of the upper lattice bone near the current collecting ear, and the thickness of the subsequent lattice bone is sequentially determined. As it goes to the center of the grid, it is possible to suppress the deterioration of the battery performance due to the corrosion of the positive grid which is remarkable at high temperature use by increasing the thickness or making it even thicker, and improve the life characteristics. Understand what you can do.

In the above embodiment, the thickness of the lattice bone is changed as a means for changing the mass per unit area of the lattice body as described in the second aspect of the present invention.
The same effect can be obtained by means for changing the mass per unit area by changing the grid area by the lattice bone as shown in the invention according to claim 3.

Further, in the present embodiment, the grid body is of the reciprocating expand type, but the band-shaped sheet is cut by a mold formed by a plurality of overlapping disk-shaped cutters, and a predetermined width is formed in another step. The same effect can be obtained for a lattice body using a rotary expanding method that expands to the size. In addition, the same effect can be obtained when a cast grid is used, and the present invention does not limit the grid body manufacturing method.

Further, although the present invention is effective in a vented lead storage battery, a sealed lead storage battery which has an exothermic reaction such as an oxygen absorption cycle at the time of charging, or has a small amount of electrolyte and easily rises in temperature due to a small heat capacity. Then, the effect is more remarkable.

[0021]

As is apparent from the above description, according to the present invention, in the grid body for a lead-acid battery, compared to the thickness of the upper grid bone in the vicinity of the current collecting ear, the size of the subsequent grid bone is reduced. Use at high temperature by making the thickness the same at the center or making it wider as it goes to the center, and making the lower lattice bone thinner than the lattice bone at the center of the lattice It is possible to suppress the deterioration of the battery performance due to the positive electrode grid corrosion, which is sometimes remarkable, to improve the life characteristics, and to realize an excellent lead storage battery.

[Brief description of the drawings]

FIG. 1 is a side view of a lattice body for explaining an embodiment of the present invention and a conventional example.

FIG. 2 is a comparison diagram of life characteristics showing the discharge capacity and the number of cycles between the battery of the embodiment of the present invention and the battery of the conventional example.

FIG. 3 is a diagram showing the amount of corrosion of each part of a lattice body after a life test in a conventional battery.

[Description of Signs] 1 Expanded lattice body 2 Current collecting ear

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Nobuyuki Takami 1006 Kadoma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. F-term (reference) 5H017 AA01 CC10 EE01 HH01 HH03 HH04

Claims (5)

[Claims] In the lead-acid battery grid, the mass per unit area of the central cell following the upper cell is compared with the mass per unit area of the upper cell near the collecting ear. The same weight, or even heavier, and, compared to the mass per unit area of the central square, the lattice unit configured to reduce the weight per unit area of the lower square Lead-acid battery characterized by the following. 2. In the grid for a lead storage battery, the thickness of the central grid bone following the upper grid bone is made equal to the thickness of the upper grid bone near the current collecting ear. 2. The lead according to claim 1, further comprising a lattice body configured to be thicker or thinner than the central lattice bone and to have a smaller thickness of the lower lattice bone. Storage battery. 3. A grid area for a lead storage battery, wherein a grid area of a central grid bone following a grid of the upper grid bone is compared with a grid area of an upper grid bone near a current collecting ear. A grid body having the same grid area or a smaller grid area, and having a grid area formed by the lower grid bone larger than the grid area formed by the central grid bone is provided. The lead-acid battery according to claim 1, wherein 4. The lead-acid battery according to claim 1, wherein the expanded grid body processed from a strip-shaped sheet material made of lead or a lead alloy is a grid body. 5. The lead-acid battery according to claim 1, wherein the battery is a sealed battery.