JPH0690935B2 - Sealed lead acid battery - Google Patents

Description

TECHNICAL FIELD The present invention relates to an improvement of a sealed lead-acid battery in which an electrolyte solution is made non-fluid and oxygen gas generated from a positive electrode plate is reacted with a negative electrode plate.

[Problems to be Solved by Conventional Techniques and Inventions] Sealed lead-acid batteries are made into a gel form by using silica fine powder or impregnated in a mat made of glass fiber etc. The oxygen gas generated by the fluidization and the positive electrode plate moves to the negative electrode plate and reacts with the negative electrode plate. On the other hand, in lead-acid batteries, sulfuric acid in the upper part of the electrolytic solution is consumed by discharging, and sulfuric acid is released from the electrode plate to the electrolytic solution by charging and settles down.Therefore, when the charging / discharging cycle is repeated, the upper part of the electrolytic solution has low specific gravity and the lower part is A stratification phenomenon called high specific gravity occurs. In a general lead-acid battery using a liquid electrolyte, this stratification can be easily eliminated by gassing during overcharge or bubbling by feeding gas into the electrolyte. However, in the sealed lead-acid battery that is the subject of the present invention, since the electrolyte is non-fluidized, stratification is unlikely to occur, but if stratification that gradually progresses is formed, it is difficult to stir the electrolyte. In addition, there is a problem that it is difficult to eliminate stratification and the accompanying decrease in capacity and sulfation under the electrode plate.

[Means for Solving Problems] The present invention solves the above problems of a sealed lead acid battery in which an electrolyte is made non-fluidic, and its gist is to provide means for partially cooling or heating the battery. The lower part or bottom part of the battery case is kept at a lower temperature than the other parts, so that the partial pressure of water vapor of the electrolytic solution impregnated in the lower part of the electrode plate group is increased by the water vapor of the electrolytic solution impregnated in the upper part of the electrode plate group. It should be smaller than the partial pressure.

[Operation] Considering the case where a part of the closed space contains dilute sulfuric acid, the gas phase contains water vapor depending on the concentration of dilute sulfuric acid, that is, the specific gravity. Table 1 shows the equilibrium water vapor pressures (mmHg) at various temperatures for the specific gravities of dilute sulfuric acid of 1.32, 1.26 and 1.20 (all values at 20 ° C.) and water. The higher the specific gravity of water vapor pressure,
Further, the lower the temperature is, the lower the temperature is, but the influence is larger in the temperature than in the specific gravity.

Therefore, if the lower part or the bottom part in the battery case is made to have a lower temperature than the other parts, a phase change occurs in which the water vapor evaporated in the high temperature part is condensed into water in the lower part or the bottom part,
The lower part of the electrolytic solution is diluted and the upper part is concentrated to easily eliminate the stratification phenomenon.

There are various means for making the temperature of the lower part or bottom of the battery case lower than that of other parts.

(A) A cooler using a coolant such as cooling water is installed at the bottom or bottom of the battery case.

(B) A cooler made of a coolant such as cooling water is placed in contact with the bottom or bottom of the battery case.

(C) The lower part of the battery has a low temperature atmosphere. For example, the lower part of the battery is immersed in cooling water, only the lower part is cooled by forced ventilation, or the battery is placed on a low temperature metal plate.

(D) Warm the upper part or lid of the battery case.

(E) The lower part or the bottom part, or the upper part or the lid of the battery case is cooled or heated by using a Peltier effect, that is, an element that causes a temperature difference due to energization. The lower part or the bottom part of the battery case may be cooled and the upper part or the lid may be heated.

Since the purpose of cooling or heating is to eliminate the stratification of the electrolytic solution, it may be performed only when stratification occurs. Therefore, when the battery is left unattended or when only float charging is performed, it is not necessary to generate water in the lower portion of the electrolytic solution by cooling or heating.

It should be noted that cooling for simply lowering the overall temperature, rather than cooling for causing a temperature difference, is often performed in large lead-acid batteries using a flowing electrolyte. But in this case,
When the temperature of the upper electrolyte is lower than that of the lower electrolyte, convection is generated in the electrolyte due to the difference in specific gravity due to the temperature difference, and the cooling efficiency is increased, so that the upper portion of the battery is generally cooled.

Further, for cooling in the assembled battery, ribs are provided on the outer wall of the battery case, and a low-temperature fluid is passed between the batteries along the outer wall from the lower side to the upper side to cool the battery from the side portion. There is an example (Jpn. App. No. 48-76478), but this is not a method for causing a temperature difference between the upper and lower sides, but a very general method for cooling the entire battery.

Further, in a liquid battery, an example in which a cooling and heating conduit is provided in the electrolytic solution at the bottom and sides of the cell (Jitsuko 38-14924)
No.), but this is one of the means for controlling the temperature of the battery, that is, merely cooling or heating the entire battery, and of course is not cooling for causing a temperature difference between parts.

None of the above examples produce a temperature difference between parts and generate water at the bottom or bottom due to a phase change.

[Example] Hereinafter, the sealed lead-acid battery of the present invention will be described with reference to an example shown in the drawings. In the figure, 1 is a positive electrode plate, 2 is a negative electrode plate, 3
Is a separator, and the separator 3 is composed of a mat made of fine fibers such as glass or hydrophilic plastic or a microporous plate, and is impregnated with and holds the electrolytic solution. 4 is a battery case
Is a cooler, and the cooler 5 is arranged at the bottom of the battery case 4. 6 is an exhaust part having a valve function, 7 is a positive electrode terminal, and 8 is a negative electrode terminal. The electrolytic solution is impregnated and held in the positive electrode plate 1, the negative electrode plate 2 and the separator 3 and is substantially non-fluidized.

In the embodiment of the present invention having such a structure, stratification of the electrolytic solution is caused by the charge / discharge cycle, and the specific gravity of the upper part of the electrode plate group is 1.2.
Assuming that the temperature is 0, the lower part is 1.32, and the temperature of the electrolyte is 45 ° C, the steam pressure in the upper part is 56 mmHg, that in the lower part is 39 mmHg, and the steam in the lower part is condensed into water. The driving force for phase change is 56-39 = 17 mmHg. When the lower part is cooled to 25 ° C. by the cooler 5 from such a state, the water vapor pressure is 56 mmHg in the upper part, but 13 mmHg in the lower part.
Since the water vapor pressure of −13 = 43 mmHg is the driving force, stratification is
43/17 ≒ 2.5, that is, it is resolved at a speed of about 2.5 times.

[Effects of the Invention] As described above, the present invention solves the problems of stratification of the electrolyte solution by the charge / discharge cycle of the sealed lead-acid battery in which the electrolyte solution is non-fluidized, and the accompanying capacity reduction and sulfation at the lower part of the electrode plate. It has been solved and is extremely effective in stabilizing the battery performance and prolonging its life.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view of an essential part showing a schematic structure of an embodiment of a sealed lead-acid battery of the present invention. 1 ... Positive electrode plate, 2 ... Negative electrode plate, 3 ... Separator, 4 ...
… Battery case, 5… Cooler, 6… Exhaust section

Claims (1)

[Claims] 1. An electrolytic solution in which a lower portion or a bottom portion of a battery case is impregnated in a lower portion of an electrode plate group by providing a means for partially cooling or heating a storage battery. The sealed lead-acid battery in which the electrolytic solution is made non-fluidized is characterized in that the partial pressure of water vapor is set to be smaller than the partial pressure of steam of the electrolytic solution impregnated in the upper part of the electrode plate group.