JPS63250049A - Sealed type lead storage battery - Google Patents

Abstract

PURPOSE:To suppress decline of battery characteristics by imparting pressure adjustment function to a case. CONSTITUTION:Electrode groups comprising positive and negative electrodes, separator and electrolyte are combined, for example those for three cells, and fixed with elastic string. A case 1 containing these groups has a raised bottom 2 with a wall structure curved inward the battery, which curves outward when internal pressure of the battery increases. A hole 3 is perforated at a part of the bottom in the case 1 and a rubber balloon 4 is fixed on the part. Furthermore, bellows 5, which are usually folded but extended by an increase in internal pressure, are mounted on the bottom 2. By the arrangement, gas generated during charging is absorbed inside the battery, not being discharged out of the battery, and decrease in water content of the electrolyte in operation and deterioration of the characteristics are suppressed.

Description

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

A. Conventional technology Sealed lead-acid batteries have a structure that suppresses the dissipation of water in the electrolyte during charging or overcharging by dissipating oxygen gas generated from the positive electrode plate during charging at the negative electrode plate. There is. Furthermore, since the case that houses the electrode plate group is made of resin molded by an injection method, it has a structure that is almost unaffected by the pressure of oxygen gas generated from the positive electrode during charging.

Problems to be Solved by the Invention In a conventionally structured battery, if the internal pressure inside the battery increases, the case will break, so a reverse valve that also serves as a safety valve is installed. This is because the case uses an injection molded product with almost no expansion. In sealed lead-acid batteries, the internal pressure of the battery increases during charging/discharging cycles or overcharging, and the check valve sometimes operates, allowing gas to be discharged from the battery. This has the disadvantage that the amount of water in the electrolyte in the battery decreases in proportion to the discharged amount, resulting in deterioration of battery characteristics.

In addition, the gas absorption capacity of the negative electrode plate increases as the pressure of oxygen gas increases, but due to the strength of the case, the internal pressure cannot be made too high, and in general, the gas absorption capacity of sealed lead-acid batteries is There is a small drawback.

Means for Solving the Problems The present invention provides a case with a pressure adjustment function. Specifically, one or a predetermined number of electrode plates consisting of positive and negative electrode plates, a separator, and an electrolyte are combined, and A predetermined pressure (electrode plate group compressive force) is applied and these are housed in a case with a pressure adjustment function. A structure in which a part of the wall of the case expands as a pressure adjustment function, such as a structure in which the bottom of the case expands, or a structure in which a part that can expand is installed in a part of the case, such as a balloon-shaped part. A structure 1 in which a structure or a part of a case is deformed by pressure, for example, a bellows-like structure is installed in a part of the case in a folded state.

Effect Due to the above structure, all gas generated during charging is absorbed within the battery without being discharged outside the battery, suppressing the decrease in moisture in the electrolyte during operation and preventing deterioration of characteristics. Can be suppressed. Compatibility with conventional batteries can be maintained by installing the pressure adjustment function in a location other than the external dimensions required for securing the battery. ! A safety valve may be installed for safety purposes, but if a dedicated charger is used, the safety valve may be removed in some cases.

In addition, because the case material does not need to have mechanical strength, especially rigidity, materials that are resistant to cracking or bursting, such as polyethylene or polypropylene, can be used as the case material, and the internal pressure of the battery can also be increased. Therefore, the gas absorption ability of the negative electrode is also improved.

Example Examples will be described below.

10 hour rate capacity consisting of ordinary positive and negative electrode plates, separators and electrolyte3. Combining 3 cells of electrode plate groups with oAh, 3
20kg/d with an elastic band covering the entire cell
The pressure was fixed at m. Note that these cells have a structure in which each cell has an independent electrolyte. These groups are stored in a case.

An example of the case is shown below.

A: As shown in Fig. 1, the bottom surface 2 of the case 1 is a curved bottom, and this wall is normally curved toward the inside of the battery, but curves toward the outside when the internal pressure of the battery increases.

B A case in which a hole 3 is made in a part of the bottom of the J, sea urchin case 1 shown in Fig. 2, and a rubber balloon 4 is fixed in this part.

C As shown in FIG. 3, a case has a structure in which a bellows 5, which is normally folded, is provided on the bottom surface 2 of the case 1, and the bellows opens when pressure increases.

The group pressure was adjusted with an elastic band, and the fixed electrode plate group was
, B, C, put it in the case, seal it and put it in the battery, B, Ci
Created. Note that safety valves are not installed in these cases.

These batteries were evaluated as follows.

■ Cycle life characteristics: Charge at a constant voltage of 2.45V/cell for 6 hours, discharge at 0.
The number of cycles until the initial capacity reached 50% was determined by repeating cycles up to 1.70 V/cell at a resistance equivalent to 250 A.

■ Overcharge life characteristics At 25°C, 0.250A discharge is performed every two weeks at a constant current of 0.05 CA, and two weeks is one cycle.
The number of cycles required to reach 50 times the initial capacity was determined.

The results are shown in FIGS. 4 and 5. FIG. 4 shows the cycle life characteristics. From this figure, it is clear that products A, B, and C of the present invention have a longer cycle life than conventionally structured batteries. Note that no significant difference was observed between products A, B, and OK of the present invention. FIG. 5 shows the results of the pan charging characteristics. From this figure, batteries A, B, and C of the present invention are conventional batteries DJ.
It can be seen that the overcharging characteristics are excellent.

Furthermore, since no breakage or explosion of the battery occurred during these tests, it is presumed that depending on the usage conditions, it may be possible to put the battery into practical use without installing a safety valve.

Effects of the Invention Since the electrode plate group has a structure that allows the electrode plate group to cope with expansion and contraction of the electrode plate group, the force that causes the outer case to break is only the pressure of the gas phase within the battery. Furthermore, since the method for changing the pressure or volume of the gas phase is easy, adjusting only the pressure of the gas phase is very effective in terms of case construction. That is, the present invention uses a case that can respond to pressure changes or volume changes in the gas phase, and this has great industrial value.

[Brief explanation of drawings]

1 to 3 are diagrams showing the cross-sectional structure of the case in the present invention, and FIG. 4 is a diagram showing cycle life characteristics. FIG. 5 is a diagram showing overcharge characteristics. 1...Case, 2...Bottom, 3...
... Hole, 4 ... Rubber balloon, 6 ... Bellows.

Claims (4)

[Claims] (1) A positive electrode plate, a negative electrode plate, a separator, and a combination of one or a predetermined number of electrode plates consisting of an electrolyte held in the separator, and a predetermined pressure applied to these electrode plate groups, which has a pressure adjustment function. A sealed lead-acid battery that is housed in a case. (2) The sealed lead-acid battery according to claim 1, wherein the wall of the storage case expands. (3) The sealed lead-acid battery according to claim 1, wherein a portion of the storage case is provided with a portion that expands under pressure. (4) The sealed lead-acid battery according to claim 1, wherein a part of the storage case is provided with a structure that deforms under pressure.