JPH02174072A - Lead-acid battery - Google Patents

Abstract

PURPOSE:To extract a stable capacity over a long period by making a positive electrode plate and a negative electrode plate thinner in thickness at the upper section in the installation direction of a storage battery than at the lower section. CONSTITUTION:A positive electrode plate 1 and a negative electrode plate 2 are made thinner in thickness at the upper section in the installation direction of a battery than at the lower section into a structure with a trapezoidal longitudinal section, and positive electrode plates 1, negative electrode plates 2 and separators 3 with uniform thickness are combined and inserted into a battery jar 4 to form a storage battery. The quantity of the electrolyte held in the separator 3 is proportional to the apparent volume of the separator 3 if the material and characteristic are the same, the separator 3 is made thicker in thickness by the quantity that the positive electrode plate 1 and the negative electrode plate 2 are made thinner in thickness, and the apparent volume is increased. The electrolyte holding strength is sharply increased, and the movement of the electrolyte can be blocked.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is particularly applicable to equipment in which it is important to reduce the maintenance of storage batteries, or to oxidizing gas (containing dilute sulfuric acid) generated from storage batteries.
This relates to lead-acid batteries suitable for use in equipment and locations where acid fog (hereinafter referred to as acid fog) may cause injury.

Conventional technology Lead-acid batteries have been used for a variety of purposes as a relatively inexpensive power source, but due to their characteristics, not everyone can use them easily. There are many reasons for this, but one reason is that dilute sulfuric acid is used as the electrolyte, and the electrolyte may flow out when the battery is damaged, and even under normal usage conditions, dilute sulfuric acid may Containing acid mist may be generated and contaminate surrounding equipment or the environment.

Conventionally, in order to remove acid mist generated from storage batteries, methods have been widely used, such as using a catalyst to cause the oxygen gas and hydrogen gas generated during charging to react and return the mixture as water into the storage battery.

Furthermore, recently, there has been an increase in the number of methods for sealing storage batteries by taking advantage of the following characteristics of lead-acid batteries. That is, when a lead-acid battery is charged, oxygen gas is first generated from the anode, and then hydrogen gas begins to be generated from the cathode after a while. Therefore, by appropriately selecting the charging conditions, it is possible to charge the storage battery in a region where almost only oxygen gas is generated. The oxygen gas generated at this time reacts with metal lead, which is a reactant of the cathode plate (oxygen gas absorption reaction), and is consumed, thereby preventing a rise in pressure inside the cell.

Taking advantage of the above-mentioned characteristics, many sealed type or sealed type lead-acid batteries have recently been manufactured.

Sealed lead-acid batteries are equipped with a cell internal pressure prevention mechanism that uses oxygen gas absorption reactions, and are made of porous materials such as fine glass fibers to reduce the amount of electrolyte and prevent the electrolyte from flowing. It has a structure that absorbs and retains this.

Sealed lead-acid batteries with this type of structure do not generate harmful acid mist, and even if the battery is tipped over, the electrolyte (dilute sulfuric acid) does not flow out, so it has recently been widely used as a power source for electronic devices. It has become possible to do so.

Problems to be Solved by the Invention As mentioned above, in a sealed lead-acid battery, most of the electrolyte is contained in the electrolyte holder and then the separator. ), the performance of the storage battery is largely determined by the separator.

However, since conventional sealed storage batteries have a series of separators, the electrolyte held in the upper part gradually moves to the lower part due to repeated charging and discharging or due to gravity over time. As a result, the amount of electrolyte in the upper part of the separator is significantly reduced. Furthermore, since the sulfuric acid content in the electrolytic solution has a higher specific gravity than water, which is another component of the electrolytic solution, it tends to collect at the lower part of the separator, and as a result, the sulfuric acid concentration increases in the lower part and decreases in the upper part.

When such a phenomenon occurs, there is a shortage of electrolyte necessary for the battery reaction in the upper part of the electrode plate, and the electrical resistance of the separator portion increases, resulting in a significant decrease in battery capacity and shortening of battery life. In addition, although there is sufficient electrolyte in the lower part, there is a problem that the electrolyte concentration gradually increases due to repeated charging and discharging, which accelerates corrosion of the lattice and deactivation of the active material. Ta.

Means for Solving the Problem In order to solve this problem, in the storage battery according to the present invention, the thickness of the upper part of the anode plate and the cathode plate is made thinner than the lower part with respect to the battery installation direction, so that a trapezoidal vertical cross section is formed. The structure is as follows. The anode plate, the cathode plate, and a separator of uniform thickness are combined and inserted into a battery case to form a storage battery.

Effect The amount of electrolyte held in the separator is proportional to the volume of the separator if the material and properties are the same. Therefore, by taking the above-mentioned measures, the separator becomes thicker in the upper part of the electrode plate by the amount that the anode plate and the cathode plate are thinner than in the lower part, and the apparent volume increases. As a result, the electrolyte holding power increases significantly, and movement of the electrolyte can be prevented.

EXAMPLE A sectional view of a lead-acid battery according to the present invention is shown in FIG. 1 in the diagram
is an anode plate, 2 is a cathode plate, 3 is a separator, and 4 is a battery case. The anode plate has a thickness of 2 m at the top and 3 m at the bottom, and a cathode plate has a thickness of 1.5 m at the top and 2.0+a at the bottom.

The separator 3 is made of many fine fibers of glass or synthetic resin, and the fiber diameter is usually 0.1~
A 10 micron one is used. A small amount of binder is sometimes used to help the fibers tangle with each other and prevent them from losing their shape. Additionally, the surface of the fibers is treated with a surfactant to improve leakage of the electrolyte.

In this embodiment, the thickness of the separator is 2.5 mm when a pressure of 20 kg/dm2 is applied.

The number of electrode plates per cell is 4 anode plates.

5 cathode plates and 8 separators, with a width of 34.2
It is inserted into a nn cell to create a storage battery with a 20 hour rate capacity of 52Ah.

In order to clarify the effects of the present invention, a conventional storage battery (a battery consisting of an anode plate with a thickness of 2.5 mm, a cathode plate with a thickness of 1.75 m+n, and a separator thickness of 2.5 mm) was used as a comparative battery. The following tests were conducted. The initial capacity of each storage battery is 52 Ah.

The storage battery according to this example and the comparative storage battery were placed at an ambient temperature of 25±2° C. and discharged at 2.6 A corresponding to a 20 hour rate current until the battery voltage reached 10.2V.

Thereafter, 120% of the amount of electricity discharged is charged with the current to 5.2. This discharging and charging cycle is repeated further, and the storage battery capacity reaches 50% of the rated capacity.
It ended when the following was reached.

The results of this test are shown in FIG.

As can be seen from the figure, the comparative storage battery had a capacity of 50% or less at the 150th cycle, but the storage battery of this example had a capacity of 47Ah at the 150th cycle.
It takes 325 cycles for the capacity to decrease to 50% or less.

In addition, the storage battery of this example and the comparative storage battery were heated at 25±2°C.
The battery was left in an atmosphere for 6 months, then supplementary charged at 5.2A for 3 hours, and the capacity was measured. The results are summarized in Figure 3. The results show that the storage battery according to the present invention has a much larger capacity than the comparative storage battery.

Effects of the Invention As described above, in the lead-acid battery of the present invention, the decrease in battery capacity during use or storage is significantly less than in conventional lead-acid batteries, and it is possible to obtain stable capacity over a long period of time. becomes.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a lead-acid battery according to an embodiment of the present invention;
Fig. 2 is a life characteristic diagram comparing the lead-acid battery according to this embodiment and a conventional lead-acid battery, and Fig. 3 is an explanatory diagram comparing the capacity of the lead-acid battery according to this embodiment and a conventional lead-acid battery after being left unused. be. 1... Anode plate, 2... Cathode plate, 3...
...Separator. Name of agent: Patent attorney Shigetaka Awano and 1 other person 1-Inchal electrode plate 2-・Electrode plate 3゛°゛Seha 0 Lake Figure 2 Mitsuka ν glare! number,

Claims (1)

[Claims] A sealed lead-acid battery comprising an anode plate, a cathode plate, and an electrolyte holder that is interposed between the two electrode plates and holds an electrolyte mainly composed of dilute sulfuric acid so that it does not flow, the anode plate and the cathode. The board is a lead-acid battery that is characterized by the thickness of the upper electrode plate being thinner than the lower part in the direction of battery installation.