JPH0546066B2 - - Google Patents

Description

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

Conventionally, sealed lead-acid batteries include a sealed lead-acid battery in which an anode plate and a cathode plate are combined via a pine-shaped retainer made of extremely thin glass fibers, and electrolyte is injected to the extent that no free liquid is present. There are gel batteries in which a gel electrolyte is injected without using a retainer. Since the manufacturing process for the latter type of gel battery is complicated, sealed lead-acid batteries have recently become the mainstream of sealed lead-acid batteries, and many types, from small to large, are being produced. . However, although this battery is a sealed type,
If the charger is used at a high temperature of 50°C or if there is an abnormality with the charger, electrolysis may occur due to evaporation or oxygen gas generated at the anode not being fully absorbed by the cathode and escaping to the outside through the safety valve. fluid decreases. When the electrolyte decreases, the adhesion between the electrode plate and the retainer deteriorates, and the diffusion of the electrolyte into the electrode plate deteriorates, resulting in a decrease in capacity.Furthermore, the electrolyte contained in the cathode plate also decreases, so the anode plate is damaged during charging. Since the absorption of oxygen gas generated in this process is promoted, overcharging current becomes easier to flow. When a large amount of current flows, the temperature rises, causing a so-called thermal runaway phenomenon in which the current increases, and the battery life becomes extremely short. Although such a phenomenon is less likely to occur in batteries for applications that do not require a long life, it is a problem especially in large batteries that require a long life.

Additionally, since the electrolyte in this battery diffuses through the contact area between the electrode plates and the retainer, it also has the disadvantage of poor diffusion and poor large current discharge characteristics, especially at low temperatures, compared to liquid lead-acid batteries. are doing.

Most of the batteries that suffer from the former drawback, that is, large batteries that generally require a long life, are either fixed to equipment or placed in a dedicated storage area.
It is rare for a single battery to be used for different purposes each time. Therefore, it is extremely unlikely that the device will be accidentally rolled over or overturned and used for a long period of time. That is, this type of battery is used for the purpose of being completely sealed and having a long life, and no particular emphasis is placed on the feature of directional freedom, which is important for sealed lead-acid batteries for other uses.

The present invention aims to provide a battery structure for such a battery that eliminates the above-mentioned drawbacks, and includes a retainer in the upper part between the electrode plates, and a glass mat used in automobile batteries, etc. in the lower part between the electrode plates. This is characterized in that a separator having an uneven portion, which is generally referred to as a separator with an embossed part or an embossed separator, is arranged, and the electrolyte level is injected to the limit of the interface between the retainer and the separator.

An embodiment of the present invention will be described.

In a battery with a 10 hour rate capacity of 50Ah that uses five anode plates 1 of 3.5mm thickness and six cathode plates 2 of 2.0mm thickness with a height of 115mm and a width of 100mm, the upper part of the electrode plate is 70mm.
Thickness is 2.0mm when a load of 20Kg/dm ² is applied.
A retainer 3 with a porosity of 88 to 90% is made of glass fibers with a diameter of 1 to 8 um made into a mat shape using a paper-making process, and a retainer 3 with a porosity of 88 to 90%, which is used in common automobile batteries, is placed in the lower 45 mm between the electrode plates. The porosity is 95 to 97%, which is made by making ~20 um of glass fiber into a pine shape using a papermaking method, and the thickness is 0.8 mm, and the porosity is 90 to 92 as specified by JISC2313.
%, a separator 4 with a total thickness of 2.0 mm on which a synthetic fiber separator with a thickness of 0.4 mm is pasted is arranged as shown in Figure 1, with the synthetic resin separator in contact with the anode plate.
I made a prototype of a 12V50Ah battery. At the same time, a battery using only the retainer 3 was manufactured as a prototype, and performance tests were conducted at the same time as the battery of the present invention.

Figures 2 to 5 show changes in liquid loss, overcharge current value, internal resistance value, and capacity, respectively, when overcharged continuously at a constant voltage of 13.8V in a constant temperature bath at 45°C. Comparing the inventive product and the conventional product, there is almost no difference in the amount of liquid reduction, but the overcharge current value and
The product of the present invention has a smaller internal resistance value and less capacity deterioration. Since the amount of liquid reduction is the same, this type of test shows that even if the contact area between the retainer and the cathode plate is about 2/3 of the entire cathode plate, it can sufficiently absorb the oxygen gas generated on the anode plate. The reason why the liquid in both cases is reduced by the same amount is thought to be that water vapor escapes to the outside through a safety valve or the like.
The product of the present invention has more electrolyte at the bottom of the battery, so even if the electrolyte decreases due to evaporation,
This is because the overcharge current does not easily flow. Similarly, the reason why the internal resistance is low is because the amount of electrolyte is large, so there is almost no effect of liquid reduction. Furthermore, the reason for the small capacity deterioration of the product of the present invention is that, similar to the reason for the low internal resistance, even if the same amount of liquid is reduced, there is a lot of electrolyte at the bottom of the battery, so there is always enough electrolyte in the retainer. This is because the diffusion of the electrolyte required for discharge is better than with conventional products. No leakage was observed in either case.

Figure 6 shows the discharge characteristics at -10°C. The product of the present invention is superior, but this is thought to be due to the fact that the electrolyte diffuses better in the portion of the automotive separator below the electrode plates than in the portion of the retainer.

As described above, even if the present invention is charged at high temperature, the overcharge current that affects the life performance is small, and capacity deterioration is small. Furthermore, it is of great industrial value in that it can provide a sealed lead-acid battery with improved discharge characteristics at low temperatures, which is one of the drawbacks of sealed lead-acid batteries.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view showing the structure of the electrode plate group in an embodiment of the present invention, and FIG. 2 is a schematic cross-sectional view showing the structure of the electrode plate group in an embodiment of the present invention.
A comparison curve diagram showing the change over time in the amount of liquid loss when charging at 13.8V, Figure 3 is a comparison curve diagram showing the change over time in the overcharge current value, and Figure 4 is also a comparison curve diagram showing the change over time in the internal resistance value. Comparative curve diagrams. Figure 5 is a comparative curve diagram showing the change in duration over time when discharging at a 1 hour rate current. Figure 6 is a comparison curve diagram showing the voltage change when discharging at a 1 hour rate current at -10°C. FIG. 1 is an anode plate, 2 is a cathode plate, 3 is a retainer, and 4 is a separator.

Claims (1)

[Claims] 1 A group of electrode plates is used, in which a pine-shaped retainer made of thin glass fiber is placed between the electrode plates, and a separator with better electrolyte diffusion is placed in the lower part between the electrode plates. A sealed lead-acid battery, characterized in that an electrolytic solution is injected only at the interface between the retainer and the separator.