JPH07320727A - Positive electrode plate for sealed lead-acid battery - Google Patents

Abstract

PURPOSE:To provide a positive electrode plate for a sealed lead-acid battery capable of enhancing capability to be charged after overdischarged and left. CONSTITUTION:An expanded grid or a punched grid formed from a sheet made of lead or a lead alloy is used as a positive current collector. The amount of an active material is limited to 0.4-0.8 gr per cm<2> of the surface area of the positive current collector.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a positive electrode plate for a sealed lead acid battery.

[0002]

2. Description of the Related Art In a conventional positive electrode plate of a sealed lead-acid battery, a positive electrode current collector is filled with a paste composed of lead oxide, water and dilute sulfuric acid, and then subjected to aging and chemical conversion steps to form a positive electrode current collector. The active material is integrated to improve adhesion. Further, in the sealed lead acid battery, in order to reduce the weight and improve the manufacturability of the electrode plate, one using an expanded grid or a punched grid made of a processed product of a sheet made of lead or a lead alloy as a positive electrode current collector is preferable. is there.

[0003]

However, in a positive electrode plate using an expanded grid or a punched grid as the positive electrode current collector, the surface of the current collector is different from that produced by casting, and therefore the current collector surface is smooth. Since the surface area of the current collector is small and the volume of the current collector is also small, there is a problem that the contact area with the active material is also small. A sealed lead-acid battery using such a positive electrode plate has low charge acceptability (current value at the beginning of charging) when it is charged after being left over-discharged, and it takes time to charge, and the capacity after recovery charging is also high. There is a problem that it becomes lower than that before leaving.

An object of the present invention is to provide a positive electrode plate for a sealed lead-acid battery which can improve charge acceptance after being left over-discharged.

[0005]

DISCLOSURE OF THE INVENTION The object of the present invention is to improve a positive electrode plate for a sealed lead-acid battery using an expanded grid or a punched grid made of a processed product of a sheet made of lead or a lead alloy as a positive electrode current collector. There is.

In the present invention, the amount of the active material per 1 cm ² of the surface area of the positive electrode current collector is 0.4 g or more and 0.8 g or less.

[0007]

In this way, the contact area between the current collector and the active material is increased by increasing the amount of the active material per 1 cm ² of the surface area of the positive electrode current collector. Further, the thickness of the lead sulfate layer in the vicinity of the current collector is reduced when the battery is left for over-discharge, so that the conductivity during charging is increased and the charge acceptability is improved.

[0008]

EXAMPLES An example of the present invention will be described in detail below.

As the positive electrode current collector, expanded grids having different surface areas in contact with the active material shown in Table 1 (different amounts of active material due to different volumes) are used, and the positive electrode plate has the same positive electrode volume ( 40 mm × 60 mm × 3 mm) was produced. A sealed lead-acid battery (2V-4Ah) was produced by using two positive electrode plates, three negative electrode plates, a retainer, and an electrolytic solution. However,
The same one is used except for the positive electrode plate.

[0010]

[Table 1] A 0.5 Ω resistor was connected to these batteries for 24 hours to allow them to be over-discharged and then left open for 1 month (in 25 ± 2 ° C).
After that, the current value and the constant current arrival time at the 10th second when the constant voltage charging under the charging condition of 2.45 V / cell, 0.3 CA cut and 8 h was performed are shown in FIG.

From this, the positive electrode current collector (expanded grid)
It can be seen that when the amount of the active material per 1 cm ² of the surface area is 0.8 g or less, the charge acceptance is equivalent to that of the cast grid. Table 2 shows the recovery capacity after recovery charging. However, the capacity before leaving it to over discharge is 100.

From this, the positive electrode current collector (expanded grid)
It can be seen that the capacity is almost recovered by setting the amount of the active material per 1 cm ² of the surface area of 0.8 g or less. This is because when the amount of the active material is 0.8 g or more, the constant current arrival time becomes long and the charging rate decreases.

[0013]

[Table 2] Moreover, the initial capacity test result of each battery is shown in FIG. Discharge conditions are 1CA (4A) constant current, final voltage 1.3V /
It is a cell. From this, it is understood that the amount of the active material per 1 cm ² of the surface area of the positive electrode current collector is 0.4 g or more in order to satisfy the capacity. This is because the plate volume is the same,
The reason for increasing the lattice surface area is that the lattice volume also increases and the amount of active material decreases.

Similar results are obtained when a punched grid is used for the positive electrode current collector.

[0015]

As described above, in the positive electrode plate for a sealed lead storage battery according to the present invention, the amount of the active material per 1 cm ² of the surface area of the positive electrode current collector is 0.4 g or more and 0.8 g or less. The amount of the active material per 1 cm ^{2 of the} body surface area increases, and the contact area between the current collector and the active material increases. For this reason, the thickness of the lead sulfate layer in the vicinity of the current collector is reduced when the battery is left for over-discharge, and as a result, the conductivity during charging is increased, and the charge acceptability can be improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between an amount of an active material per 1 cm ² of surface area of a positive electrode current collector, a current value at 10 seconds of charging, and a constant current arrival time.

FIG. 2 is a diagram showing the amount of active material per 1 cm ² of surface area of a positive electrode current collector and the initial capacity of a battery.

Claims (1)

[Claims] 1. A positive electrode plate for a sealed lead-acid battery using an expanded grid or a punched grid made of a processed product of a sheet made of lead or a lead alloy as a positive electrode current collector, wherein the surface area of the positive electrode current collector is 1 cm ² 0.4 active material
A positive electrode plate for a sealed lead acid battery, which is characterized in that it is not less than g and not more than 0.8 g.