JPH01175175A - Sealed type lead-acid battery - Google Patents

Abstract

PURPOSE:To improve the life and safety by impregnating a gelatinous electrolytic solution made of inorganic oxide into synthetic fibers with the water absorption property and arranging it between a positive electrode plate and a negative electrode plate. CONSTITUTION:A solution dispersed with silica grains in 'Lanseal(R)' F or a solution mixed with 'Snowtex(R)' and dilute sulfuric acid with the specific gravity of 1.320, for example, is impregnated into synthetic fibers made of acrylonitrile polymer with the absorption property and gelatinized, the synthetic fibers 1 holding a gelatinous electrolytic solution and a linter separator 2 are arranged and assembled between a positive electrode plate 3 and a negative electrode plate 4. When the linter separator 2 is concurrently used, a short circuit between the electrode plates due to the dendrite liable to occur in a gel battery can be prevented, furthermore the fluidization of the gel electrolytic solution 5 due to the shrinkage or thioxotropy of a gel electrolyte is improved, and the life and safety can be improved.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a sealed lead acid battery.

Conventional technology Previously, this type of lead-acid battery had a porous separator such as a glass mat interposed between the anode and cathode plates to limit and absorb the electrolyte to eliminate excess liquid; Some are gelled and fixed using silica sol or water glass. These devices do not have a flowing electrolyte, and the cathode active material absorbs the gas generated from the anode plate and reduces it to water, so there is no gas leakage during charging, making it possible to seal the battery.

Problems to be Solved by the Invention However, in particular, the gel electrolyte has the following problems: (1) The gel electrolyte shrinks over time, causing a separation phenomenon in which the retained electrolyte is separated.

(2) There is thixotropy, where the gel becomes a sol due to vibration or impact and exhibits fluidity.

(3) Gel electrolytes tend to generate dendrites. These disadvantages pose problems as a sealed lead-acid battery.

In other words, if (1) is used for a long period of time, the liquid in the gel electrolyte will decrease and the capacity will decrease. In order to prevent this, it has been considered that a compound having a high water absorption ability in or around a pH neutral region is placed around the gel electrolyte layer to prevent water evaporation. However, in this case, the water coming out to the surface of the gel electrolyte layer is retained by a compound with high absorption ability, so water inevitably collects on the surface of the electrolyte and the amount of water in the electrolyte decreases. As a result, the specific gravity of the electrolyte becomes unevenly distributed,
This is not very good for battery performance. Moreover, the liquid that comes out as a separating liquid on the surface of the gel electrolyte naturally contains not only water but also sulfuric acid. Therefore, the PH region is quite shifted, and unless the PH is near the neutral region, P has no absorption power.
H-dependent compounds cannot hold liquid very well.

In addition, in (2), there is a risk that the gel electrolyte may flow due to vibration or the like and come out of the safety valve, which may cause a failure of the safety valve. In (3), the dendrites cause a short circuit between the electrode plates.

Gel electrolytes have such problems.

Means for Solving the Problems The present invention solves the above problems, improves the gel electrolyte, and improves the performance of this type of sealed battery. In other words, it is characterized by a water-absorbent synthetic fiber that holds a gel electrolyte and is placed between the electrode plates, and this synthetic fiber is mixed with or laminated with glass fiber, a super absorbent resin, or both. You may do so.

Operation The present invention has the above-mentioned characteristics, thereby making it possible to improve the shrinkage of the gel electrolyte and prevent the fluidization of the gel due to vibration or the like.

Example An embodiment of the present invention will be described.

Figure 1 shows a solution in which silica particles are dispersed in a synthetic fiber 1 made of an absorbent acrylonitrile polymer (for example, "Lanseal F", a trade name manufactured by Nippon Exlan ■) (for example, manufactured by Nissan Chemical ■). Product name: “Snowtex”)
and dilute sulfuric acid (specific gravity 1.320) to form a gel, and the synthetic fiber 1 holding the gel electrolyte and the linter separator 2 are placed between the anode plate 3 and the cathode plate 4. It is in assembled condition.

FIG. 2 shows a conventional gel battery, in which only a solution of a solution containing dispersed silica particles and a mixed solution of dilute sulfuric acid is injected between an anode plate 3 and a cathode plate 4 to form a gel and assembled. Note that 6 is a safety valve and 7 is a battery case.

These two types of sealed lead-acid batteries (the inventive product and the conventional product)
Regarding the case of using a trickle of t'2.27V in °C,
Figure 3 shows the change in weight loss rate of the battery over time. It can be seen that the weight loss of the product of the present invention is smaller than that of the conventional product. Weight loss may occur because moisture evaporates from the gel electrolyte and permeates through the battery case, or because the liquid that comes out of the gel electrolyte or from the electrode plate with a separating liquid may be released from gas or diffused during charging. This is thought to be because it leaves as fog. Therefore, unlike conventional products, if only the gel electrolyte is used, the separating liquid etc. will evaporate and the product will shrink quickly, resulting in a large weight loss. However, in the product of the present invention, which holds the gel with water-absorbing synthetic fibers, the water-absorbing synthetic fibers hold the releasing liquid, so weight loss is reduced, and it is thought that shrinkage of the gel is also suppressed. .

Furthermore, since there are water-absorbing synthetic fibers throughout the gel, uneven distribution of liquid does not occur.

On the other hand, these two types of sealed lead-acid batteries were subjected to a vibration test under the conditions of a frequency of 20H2, an amplitude of 3cIn, and an acceleration of 3G. As a result, in the conventional product, the gel electrolyte turned into a sol and exhibited fluidity, but in the product of the present invention, the gel electrolyte was retained by the synthetic fibers and did not exhibit fluidity. Furthermore, since there is no gel around the electrode group, the weight is light, weight energy is dominant, and gas absorption reactions are facilitated.

Furthermore, when a linter separator 2 is used in combination as shown in FIG. 1, it is possible to further prevent short circuits between electrode plates caused by dendrites, which tend to occur in gel batteries.

It is further preferable to add glass fiber to the water-absorbing synthetic fiber 1 to increase mechanical strength and improve workability. It is also desirable to mix a super absorbent resin into these fibers to improve the ability to retain water and electrolyte in the gel electrolyte.

However, if the amount of super absorbent resin is large, the gel electrolyte will shrink more easily and the internal resistance will increase, so the usage environment
It is necessary to limit the amount depending on conditions etc.

PbO, which is the anode active material, is a strong oxidizing agent, and O, which is generated during charging, is very active, so organic substances are likely to react and change, so the part in contact with the anode plate is made of glass. It is also possible to arrange a mat or the like made of fibers and attach the water-absorbing synthetic fibers 1 thereto so that the gel electrolyte is held in a double layer of fibers.

Effects of the Invention As described above, the sealed lead-acid battery of the present invention improves the shrinkage of gel electrolyte and the fluidization caused by indexability, which are disadvantages of gel electrolyte, and improves lifespan and safety. It has great industrial value.

[Brief explanation of the drawing]

Fig. 1 is a schematic cross-sectional view showing an embodiment of the present invention, Fig. 2 is a cross-sectional view schematically showing a conventional sealed lead-acid battery, and Fig. 3 is a comparative curve diagram showing changes in battery weight loss rate over time. be. 1 is a synthetic fiber, 2 is a linter separator, 3 is an anode plate,
4 is the cathode plate, 5 is the gel electrolyte, 6 is the safety valve, and 7 is the battery case.

Claims (1)

[Claims] 1. A sealed lead-acid battery, characterized in that a water-absorbing synthetic fiber holds a gel electrolyte made of an inorganic oxide and is placed between an anode plate and a cathode plate.