JPS61245463A - Enclosed lead storage battery - Google Patents

Abstract

PURPOSE:To achieve long service life of enclosed lead storage battery through an inexpensive separator having good liquid suction performance and high tensile strength by forming the separator with compound of fibrillar synthetic fiber having water filtering factor higher than specific level, mono-filament fiber and inorganic powder. CONSTITUTION:Liquid suction separator is formed with compound of 10-30wt% of fibrillar synthetic fiber having the water filtering factor higher than 5sec/g, 10-40wt% of mono-filament fiber and 30-70wt% of inorganic powder such as diatom earth, perlite, etc. Said separator and gelatinized electrolyte are combined to produce an enclosed lead storage battery employing an inexpensive separator having good liquid suction performance and high tensile strength, resulting in a cell suitable for emergency power source in vehicle.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is applicable not only to conventional small sealed lead-acid batteries such as emergency power supplies and power supplies for portable equipment, but also to larger-sized stationary batteries, automotive batteries, etc. The purpose of this invention is to provide a sealed lead-acid battery that can also be used for electric vehicles.

The conventional liquid fixing method for sealed lead-acid batteries is the fine glass mat method, in which a liquid electrolyte is held in a fine glass mat separator made of fine glass fibers with an average fiber diameter of about 1 μm. There is a gel method that uses a gel electrolyte solution, and a combination method that uses a separator and a gel electrolyte solution to take advantage of these advantages.

In addition, as the combination method, there are a method using a fine glass mat as the separator, and a method using a separator such as a sintered PvC or a paper separator used in a so-called flowing electrolyte type lead-acid battery.

■(Account) However, among these combined methods, those using fine glass mats had the disadvantage that the fine glass mats were expensive and the field of use was limited. In those using separators used in storage batteries, the density of the separator is high and the porosity is low at about 60%, so there is a problem that the amount of electrolyte retained is small and the battery capacity is inferior. Due to the lack of active material retention, the active material has a short lifespan.

In view of the above points, the present invention has been made with the aim of providing a long-life and inexpensive sealed lead-acid battery that uses a liquid-absorbing separator and a gelled electrolyte in combination. It is.

That is, the first aspect of the present invention is characterized in that the separator contains 10 to 30% by weight of fibrillar synthetic fibers, 10 to 40% by weight of monofilamentous fibers, and 30 to 70% by weight of inorganic powder. The fibrillar synthetic fibers have a freeness of 5 seconds/g or more (hereinafter referred to as high permeability fibrillar synthetic fibers).

Further, the second invention is characterized in that the separator contains 15% by weight or less of glass fiber, 10 to 30% by weight of highly permeable fibrillar synthetic fiber, 10 to 40% by weight of monofilament fiber, and 30 to 70% by weight of highly permeable fibrillar synthetic fiber. % by weight of an inorganic powder, and the glass fibers have an average fiber diameter of 1.0 μm or less (hereinafter referred to as fine glass fibers).

Fruit 110- The present invention will be explained below with reference to one embodiment thereof.

That is, before assembly, two positive electrode plates and three negative electrode plates, which had been provided with sulfate groups in advance, were stacked with a separator having the composition shown in Table 1 interposed therebetween to obtain an electrode group. The size of this positive electrode plate and negative electrode plate is 450 as in height and 14 in width, respectively.
0m5. Thickness 4mm, height 450Il1m, width 1
It was 40m++w and 3III+ thick. After storing this electrode group in a battery container, an electrolytic solution in which 3% by weight of silicon dioxide is dispersed in dilute sulfuric acid with a specific gravity of 1.220 to 1.280 is injected in an amount of 5 to 15% more than the space volume of the electrode group. The battery was allowed to stand still to allow the electrolyte to gel. Thereafter, a top cover with a valve was attached to the battery case and the battery was charged, completing a sealed lead-acid battery according to the present invention. The separators shown in Table 1 are those with a freeness of 10 seconds/g made of polyethylene as a highly permeable fibrillar synthetic fiber, those with a fiber diameter of 8μ made of polyester as a monofilament fiber, and those made with inorganic powder. Diatomaceous earth was used as the material.

Sealed lead acid battery a according to the present invention as described above.

A conventional sealed lead-acid battery b using the same electrode plate and using a fine glass mat as a separator and a gel electrolyte, and a sintered PvC battery using the same electrode plate.
A conventional sealed lead-acid battery C using a gel electrolyte as well as the separator shown in Table 1 was tested for cycle life characteristics as follows. That is, alternate charging and discharging is performed by repeating discharging at a depth of discharge of 50% and charging at 120% relative to the discharge amount, and a capacity test with a discharge current of 5 A is inserted as appropriate during this alternate charging and discharging.
The discharge duration was measured. The results are shown in FIG. 1. The test temperature at this time was 25° C., and the final voltage of the discharge duration was 1.80V.

It can be seen from FIG. 1 that the performance of the sealed lead-acid battery a according to the present invention is extremely excellent.

The reasons for this are as follows. In other words, the polyethylene used as the highly permeable fibrillar synthetic fiber of the separator of the sealed lead-acid battery a and the polyester used as the monofilament fiber are inherently poor in hydrophilicity, so when used in combination with a gelled electrolyte, It is believed that a continuous gas movement path is formed.

In addition, silica-based inorganic powders such as perlite and diatomaceous earth,
Its particle size is larger than that of silicon dioxide used to gel dilute sulfuric acid, thus preventing the silica skeleton structure formed by silicon dioxide from becoming too dense as it gels.
Gives favorable results to battery performance. This is because if this skeletal structure becomes too dense, it will be difficult to secure a passage for gas movement, and it will also be difficult for the electrolyte to move, which will adversely affect the capacity and life performance of the battery.

Although the present invention was applied to a paste-type sealed lead-acid battery in the first embodiment, the present invention is not limited thereto, and can also be applied to a clad-type sealed lead-acid battery.

Based on Example 1, the conditions for the separator used in the present invention include small pore diameter and high tensile strength.

As an experiment to show the size of this pore diameter, there is a method in which a separator is stood vertically, the liquid is sucked up from below, and the time required to suck up the liquid to a certain height is measured. In other words, in this experiment, it was recognized that the longer the suction time was, the smaller the pore diameter of the separator was.

Taking all these points into consideration, the conditions for the separator according to the present invention are listed as follows: a''-c.

a. Stand the separator vertically, 1.30d from the bottom
The liquid absorption property required to suck up 90 IIm of dilute sulfuric acid is 600 seconds or more.

b, tensile strength is 0. Must be 25Kg/15++n or more.

C0 maximum pore diameter is 30μ or less.

Here, several separators were tested under the above conditions, and the results shown in Table 2 were obtained. Table 2 also shows the price of separator raw materials as an index with the conventional so-called fine glass matte separator N set as 100.

The fine glass fibers used in Table 2 all have an average fiber diameter of 0.6 μm.

From Table 2, the following can be said. That is, it is generally known that when fibrillar synthetic fibers are used, the strength of the separator can be improved because the branched fibers cause more intertwining between the fibers than when monofilament fibers are used. However, as can be seen by comparing separators B, E, and ■, in which the composition ratio of the mixture is the same but the freeness of the fibrillar synthetic fibers is changed, any fibrillar synthetic fiber can be used. isn't it. That is, as the freeness decreases, the tensile strength decreases, so the freeness of this fibrillar synthetic fiber must be at least 5 seconds/g.

Furthermore, separator J in which the mixing ratio of fibrillar synthetic fibers is less than 10% by weight does not have sufficient tensile strength, and conversely, when the mixing ratio exceeds 30% by weight, the resulting separator has a high density. Therefore, it is expensive and undesirable. In the examples, polyethylene was used as the fibrillar synthetic fiber, but it is not limited to this, and the same effect can be expected even if acrylic or the like is used.

Separator C with different mixing ratios of inorganic powder
, E, and L, the mixing ratio of inorganic powder must be at least 30% by weight in order to improve the liquid absorption properties. However, if this mixing ratio exceeds 70% by weight, it becomes impossible to fix the inorganic powder between the fibers in the papermaking process, and the strength becomes extremely weak, making it difficult to put it into practical use.

The mixing ratio of monofilament fibers is 10 to 4, depending on the mixing ratio of fibrillar synthetic fibers and inorganic powder.
It is appropriate to set it to 0% by weight. Further, the number of types of monofilament fibers does not need to be one, and two or more types may be mixed as in separator A.

As the amount of fine glass fibers increases, the liquid absorption properties tend to deteriorate and the price also increases, so it is desirable to keep the amount as small as possible. From this point of view, it is appropriate to mix at a ratio of 15% by weight or less.

Similarly, good results can be obtained with fine glass fibers if the average fiber diameter is 1.0μ or less, but if the average fiber diameter is 2.
If it exceeds 0μ, the characteristics of the separator will deteriorate, which is undesirable.

Kohada ■Tachiki Like this, 15% by weight or less of fine glass fibers, 10-3
The separator formed from a mixture of 0% by weight of highly permeable fibrillar synthetic fibers, 10-40% by weight of monofilamentary fibers, and 30-70% by weight of inorganic powder has good liquid absorption properties and high tensile strength. It is strong, inexpensive, and easy to process.

As described in Example 1, by applying such a separator to a sealed lead-acid battery using a gelled electrolyte, an excellent battery can be provided.

In other words, the present invention has extremely great industrial value.

[Brief explanation of the drawing]

FIG. 1 shows a sealed lead-acid battery a in an embodiment of the present invention.
FIG. 2 is a graph showing cycle life characteristics when sealed lead-acid batteries A and C not according to the present invention were tested.

Claims (1)

[Scope of Claims] 1) A sealed lead-acid battery using a liquid-absorbing separator and a gelled electrolyte in combination, in which the separator is composed of 10 to 30% by weight of fibrillar synthetic fibers and 10 to 40% by weight of monofilament-like synthetic fibers. 1. A sealed lead-acid battery formed from a mixture of fibers and 30 to 70% by weight of inorganic powder, wherein the fibrillar synthetic fibers have a freeness of 5 seconds/g or more. 2) In a sealed lead-acid battery that uses a liquid-absorbing separator and a gelled electrolyte in combination, the separator comprises 15% by weight or less of glass fiber, 10-30% by weight of fibrillar synthetic fiber, and 10-40% by weight.
of monofilamentary fibers and 30 to 70% by weight of an inorganic powder, and the glass fibers are
．． A sealed lead-acid battery having an average fiber diameter of 0μ or less and a fibrillar synthetic fiber having a freeness of 5 seconds/g or more.