JPS5960965A - Manufacture of lead-acid battery - Google Patents

Abstract

PURPOSE:To increase cycle life by forming a lead sulfate layer on the interface between a substrate and an active material and by oxidizing this layer to form a dense oxide layer on the surface of the substrate, when a cathode plate is oxidized in dilute sulfuric acid solution. CONSTITUTION:When a lead-acid battery using antimony free lead alloy such as lead-calcium alloy is initially charged, after pouring dilute sulfuric acid, initial charge of the battery is continued for 10hr, then discontinued for 8hr, and continued again until the specified amount of charge is completed. When an electrode plate comprising a cathode substrate of lead or lead alloy is oxidized anodically, a lead sulfate layer is formed on the interface between the substrate and an active material, then the layer is oxidized, thereby a dense oxide layer is formed on the surface of the substrate. Therefore, penetration of electrolyte into the substrate is suppressed and local reaction caused by the substrate, lead oxide, and dilute sulfuric acid is prevented to increase cycle life and reduce self discharge.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved method for producing lead-acid batteries using antimony-free lead alloys such as lead alloys and lead-calcium-tin alloys, so-called antimony-free alloys. The purpose is to obtain a lead-acid battery with a long life and low self-discharge.

In general, from the viewpoint of suppressing gas generation and saving the effort of collecting water, the anode of a lead-acid battery using an antimony-free alloy as described above has no performance difference in shallow discharge compared to one using a lead-antimony alloy. However, in the cycle life where deep charging and discharging are repeated, there is a drawback that the performance is significantly lower than that using lead-antimono alloy.

Most commonly, the anode of a lead-acid battery is either oxidized to form a layer of lead dioxide on the substrate surface when the battery is being charged, or this layer is porous so that the electrolyte easily penetrates the oxide. The corrosion rate of the base increases as the battery charges and discharges, causing the active material to fall off and becoming one of the causes of shortening the life of the battery.

In lead-acid batteries using this type of substrate, it has been proposed to add phosphoric acid to the electrolyte or active material. However, the addition of phosphoric acid has the disadvantage that it eliminates the advantage of low self-discharge of lead-acid batteries using antimony-free alloy substrates.

The present invention aims to eliminate the above-mentioned conventional drawbacks by forming a dense oxide at the interface between the base and active material of the anode plate, thereby suppressing penetration of the electrolyte into the interior of the base. be.

That is, the present invention forms a lead sulfate layer at the interface between the substrate and the active material when oxidizing the anode plate in dilute sulfuric acid, and forms a dense oxide layer on the surface of the substrate by oxidizing the lead sulfate layer. This increases cycle life, thereby increasing cycle life.
This is based on the discovery that a lead-acid battery with low self-discharge can be obtained.

An embodiment of the present invention will be described below.

Example 1 Lead-acid batteries A, B, and C with a theoretical capacity after charging of 12 A%, each consisting of one anode plate and two cathode plates assembled using paste-type uncharged plates obtained according to a conventional method, were manufactured. Each lead acid battery A
, B, and C were injected with dilute sulfuric acid having a specific gravity of 1.210, and charged with a current of 300% of the theoretical capacity for 18 hours. At that time, lead-acid battery A was charged using the conventional method, lead-acid battery B was charged 10 hours after the start of energization, and charging was resumed 8 hours later to reach the specified amount of charge, and lead-acid battery C was charged 10 hours after energization started. After 8 hours, remove one anode plate,
The substrate was washed with running water and dried with hot air at 120° C. for 30 minutes to remove the active material from the substrate, and the oxide adhering to the substrate surface was subjected to X-ray diffraction analysis.

FIG. 1 shows the X-ray diffraction pattern of the oxide on the surface of the substrate sampled from lead-acid battery C.

The X-ray diffraction pattern is from an ASTM card, and the composition of the oxide on the substrate surface is 1 lead sulfate and 2 lead dioxide (β-P')Ox.
), 3 (a P box), and the lead sulfate content was 60 to 80% based on the weight loss rate by thermal gravity nail analysis using the same sample.

FIG. 2 shows the changes in capacity of lead-acid battery A and lead-acid battery B during their cycle life, with initial capacity set at 100. In addition, the discharge is 4
A charge/discharge cycle was repeated in a water bath at 40° C. for about 30 minutes at A and then charged at IA for 24 hours.

As is clear from the above examples, a lead-acid battery obtained by forming lead sulfate as seen from the X-ray diffraction diagram shown in FIG. 1 at the interface between the substrate and the active material and oxidizing the lead sulfate. It can be seen that the cycle life of battery B is longer than that of conventional lead acid battery A.

Example 2 The lead-acid battery A and the lead-acid battery B were left in a fully charged state at a constant temperature of 40°C for 20 days, and the low-temperature high-rate discharge capacity before being left was reduced to 0.
1. The remaining capacity ratio (C2/
CI X 100) (%) was determined. Note that the discharge conditions were -15°C and 6OA discharge.

The results are shown in Table 1.

Table 1 shows that lead-acid battery B, in which lead sulfate was formed at the interface between the substrate and the active material, had improved self-discharge compared to lead-acid battery A, which was anodized using the conventional method.

This is because the lead sulfate layer formed on the surface of the substrate is anodized, forming a lead dioxide layer with higher density than the lead dioxide layer formed by conventional methods, which allows the electrolyte to penetrate into the substrate. It is thought that this is because a local reaction involving the substrate, lead dioxide, and dilute sulfuric acid occurred.

As described above, the present invention makes it possible to obtain a high-performance S4) storage battery by a simple method, and has great industrial value.

[Brief explanation of drawings]

1st [71 is an X-ray diffraction diagram in one implementation of the present invention, 2nd
The figure is a comparative curve diagram of charge/discharge cycle characteristics of lead-acid batteries in an example of the present invention and a comparative example. 1 is lead sulfate (pbso4), 2 is lead oxide (β-P'bOf),

Claims (1)

[Claims] 1. A method for producing a lead-acid 'Fi' pond, which comprises: forming a lead sulfate layer at the interface between the base and the active material during anodization of an uncharged electrode plate made of a lead or lead alloy anode base;