JPS6065450A - Sealed lead storage battery - Google Patents

Abstract

PURPOSE:To suppress expansion of the end portions of a negative plate so as to prevent any contact between the negative plate and a positive plate by using a negative plate formed using an expanded grid as well as a mat-like separator and making the end portions of the separator touching the cut ends of the negative plate impermeable to electrolyte. CONSTITUTION:A sealed lead storage battery is consituted by using an expanded grid for a negative plate and interposing a mat-like separator 9 made of glass fiber between a positive plate and the negative plate. The surface of the belt-like end portion of the separator 9 touching the cut end of the negative plate is made impermeable to electrolyte by being coated and solidified with a denatured polypropylene resin 8. The above coating may be performed with another resin, adhesive, tape or the like instead of the resin 8. The width of the end portions of the separator 9 coated and solidified with the resin 8 is adjusted to be at least 1/4 and smaller than 1/2 of the lateral dimension of the mesh of the end portions of the expanded grid of a negative plate so that these areas have impermeability to electrolyte. By the means mentioned above, expansion of an active material existing in the end portions of the negative plate is suppressed, thereby preventing any short circuits which might be caused between a positive plate and the negative plate.

Description

[Detailed description of the invention] Industrial applications The present invention uses an expanded grating for the negative electrode plate.

The present invention also relates to an improvement in a sealed lead-acid battery equipped with a matte separator.

Conventional Structures and Their Problems In recent years, sealed lead-acid batteries have been widely used as portable power sources, emergency power sources, and the like. The feature of this battery is that the electrolyte is impregnated into a mat separator made of glass fiber9 or the electrolyte is made into a gel, which prevents the electrolyte from flowing and leaking out of the battery. This is what is happening. Recently, there has been a growing demand for smaller and lighter batteries for this type of battery, and for the purpose of reducing the weight of the electrode grid, a so-called extraction method is used to manufacture the grid by continuously machining lead alloy sheets. The band system has started to be implemented. However, in the negative electrode plate using the conventional cast lattice shown in FIG. 1, the frame 1 of the lattice surrounds the active material 2 and holds the active material, but the
In the negative electrode plate using the Exno-Kundo lattice shown in the figure, in order to continuously cut the electrode plate, the active material 2
The structure is such that the lattice 1 does not hold the edges of the lattice. This difference in structure causes the following problems.

When a lead-acid battery is used for charging and discharging cycles, the active material 2 expands at the ends of the negative electrode plate as shown in FIG. 3 due to repeated chemical reactions between metal lead and lead sulfate.

As the active material expands, it may come into contact with the positive electrode plate through the gap between the separator and the inner wall of the battery case, resulting in a short circuit.

Purpose of the Invention The present invention provides a sealed lead-acid battery that uses an expanded lattice for the negative electrode plate and is equipped with a matte separator, by suppressing the expansion of the active material at the cut end of the negative electrode plate. The purpose is to prevent contact short circuits.

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a sealed lead-acid battery that uses an expanded lattice for the negative electrode plate and is equipped with a matte separator, in which the end of the separator in contact with the cut end of the negative electrode plate is free of electrolyte. It is characterized by a transparent structure. In order to make the separator impermeable to liquids, the surface of the separator end is covered with adhesive, hot-melt resin, or tape. Further, the range of the separator through which the electrolytic solution does not permeate is preferably set to be at least Z and less than % of the horizontal dimension of the expanded lattice network from the cut end of the separator to the end of the negative electrode plate.

Description of examples Hereinafter, the present invention will be explained with reference to examples.

The following table shows the structure of a battery manufactured using a battery cell 7 having internal dimensions of width 130-2, height 80-2, and thickness 14 mm. Battery A
is an example of the present invention, and battery B is a conventional example. Since the dimensions of each component are the same, a typical configuration will be explained with reference to the schematic diagram of FIG. The battery has a structure in which one positive electrode plate 3, two negative electrode plates 4, and a cloak-type separator 5 made of glass fiber are interposed between the two negative electrode plates. In Conventional Example B, the cape-type separator 6 is used as it is, and in Power Tree Invention Battery A, the separator 9 shown in FIG. are using.

Both the positive electrode plate and the negative electrode plate use an expanded lattice, and the mesh 6 of the expanded lattice has the same dimensions of 6 squares in length and 11 squares in width.

Charging and discharging cycle test for the above two types of batteries A and B (Charging: 2 hours, 45V constant voltage, 6 hours charging at maximum current 4A,
The discharge was carried out at 2 A with a final voltage of 1.75 V) and the results are shown in FIG. As shown in the figure, conventional battery B could no longer be discharged at the 151st cycle due to a short circuit caused by expansion of the negative electrode active material. However, even when battery A of the present invention was repeatedly charged and discharged for 350 cycles, no short circuit occurred.

Regarding conventional battery B, after the 161st cycle life,
When battery A of the present invention was disassembled and observed after the 360th cycle, it was found that the negative electrode active material of conventional battery B had an expanded dimension of 2+iI+1 or more in the width direction and was in contact with the positive electrode plate. It was found that in the battery A of the present invention, the noise was suppressed to less than 2 screams at most. In this example, modified polypropylene resin was used to cover and fix both ends of the separator, but the same effect can be obtained by solidifying or covering the ends of the separator with other acid-resistant hot melt resins, adhesives, tapes, etc. Effects can be obtained. In principle, by coating or solidifying the ends of the separator, it is possible to create an electrolyte-impermeable structure and supply the active material at the end of the negative electrode plate with the electrolyte necessary for charge/discharge reactions. This is to control the expansion of the active material by reducing the reaction efficiency of the active material at the edge of the electrode plate.

Regarding the width of covering or solidifying both ends of the separator, 1) In addition to the parts where the separator protrudes from the negative electrode plate to the left and right, it is sufficient to suppress the expansion of the active material by simply covering less than 1 lateral dimension of the expanded lattice network. There is a risk of a short circuit due to failure to do so. On the other hand, if one or more of the horizontal dimensions of the expanded lattice network are covered, although the expansion of the active material can be suppressed, the capacity of the battery will be extremely reduced.

In other words, it has been found that the optimum l for covering or solidifying both ends of the separator is a range that is greater than or equal to Z and less than % of the horizontal dimension of the expanded lattice network at the end of the negative electrode plate from the cut end of the separator. Ta.

On the other hand, coating or solidifying both ends of the separator gives strength to the separator itself, which prevents the ends of the separator from breaking or crushing during the manufacture of the electrode plate group, and also makes it easier to position the separator. It also has the advantage of being easy to do.

Effects of the Invention As described above, according to the present invention, the following effects can be obtained in a sealed lead-acid battery that uses an expanded lattice for the negative electrode plate and is equipped with a matte separator.

(1) By suppressing the expansion of the active material at the end of the negative electrode plate, contact short circuit with the positive electrode plate can be prevented.

(2) The ends of the separator may break during the manufacture of the electrode plate group.
It has the advantage that it is less likely to be crushed, and furthermore, the position of the separator is easy to determine, and the pole configuration is easy.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of a negative plate using a conventional cast grid, Figure 2 is a schematic diagram of a negative plate using an expanded grid, and Figure 3 is a diagram showing the expansion of the active material due to charge/discharge cycles. FIG. 5 is a perspective view of a separator in an embodiment of the present invention, and FIG. 6 is a characteristic diagram showing the results of a cycle life test. 1... Lattice, 2... Active material, 3...
...Positive electrode plate, 4...Negative electrode plate, ts...
・Separator, 6...Mesh of expanded band lattice, 7...Electroconductor, 8...Resin coating for electrolyte impermeability, 9... ...Separator. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 3 Figure 5 Figure 6 Zaifuru i lol CL

Claims (3)

[Claims] (1) A sealed lead-acid battery using an expanded lattice as a negative electrode plate and equipped with a matte separator, in which the end of the separator in contact with the cut end of the negative electrode plate has an electrolyte-impermeable structure. Characteristics of sealed lead-acid batteries. (2) Claim 1 in which the ends of the separator are solidified with adhesive or resin, or the surface is covered with tape.
Sealed lead-acid batteries as described in section. (3) The area extending from the cut end of the separator to Z or more and less than % of the horizontal dimension of the expanded lattice network at the end of the negative electrode plate has an electrolyte impermeable structure.
Sealed lead-acid battery according to paragraph 2 or paragraph 2.