JPH01143150A - Manufacture of electrode plate for lead storage battery - Google Patents

Abstract

PURPOSE:To improve the performance stored after being overcharged by heat- treating at 170$ or above a current collector formed with an Sn layer or a Pb-Sn layer on the surface by dip brazing. CONSTITUTION:A Pb-Ca alloy current collector is immersed in a fused Sn or Pb-Sn alloy bath, an Sn or Pb-Sn alloy layer is formed on the surface, then it is heat-treated at 170 deg. or above for the preset time. As a result, Sn is diffused in a current collector alloy matrix to prevent the collapse of the alloy layer, and an Sn-rich current collector which is effective for the overdischarge shelf performance can be obtained. The diffusion of Sn into the current collector alloy depends on the heat treatment temperature, the collapse of the current collector surface alloy layer can be suppressed as the diffusion of Sn proceeds toward the inside of the alloy layer. The performance stored after being discharged can be thereby improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for manufacturing a lead-acid battery with improved charging performance after being left over-discharged.

BACKGROUND OF THE INVENTION Generally, if a lead-acid battery is left unused for a long period of time or left over-discharged, it will self-discharge and become unchargeable. Therefore,
Conventionally, in order to improve this drawback, improvements have been made to the lattice alloy of lead-acid batteries and the treatment of the lattice-active material interface. Ca-based alloys are used to reduce self-discharge.

In addition, as measures to improve the overdischarge storage performance, it is known to increase the Sn content of the lattice alloy and to plate the surface of the lattice with Sn or Pb-Sn.

Problems to be Solved by the Invention However, in order to improve the overdischarge performance, the Sn content of the lattice alloy may be increased, or the Sn content on the lattice surface may be increased.
, Pb-Sn alloy plating has the following disadvantages. That is, as the Sn content of the lattice alloy increases, the price becomes very high.

In addition, during plating treatment, the plating layer elutes and collapses during chemical formation or charging, reducing the effect on overdischarge storage performance, and the eluted Sn deposits dendrites on the cathode plate, causing short-circuiting with the anode plate. This problematic drawback also applies to forming an alloy layer on the surface of a current collector by dipping.

Means for Solving the Problems The present invention eliminates the above-mentioned drawbacks by heat-treating a current collector whose surface is coated with SnN or Pb-5nJi by dipping at 170"C or higher.

action Charging performance after over-discharging is improved.

If the lead-acid battery of the example is left uncharged for a long period of time, self-discharge will increase, and if left uncharged, it will become unchargeable. This makes Pb non-reactive at the lattice-active material interface.
This is because a film is formed and the internal resistance of the battery increases. In particular, when left over-discharged, the internal resistance of only the anode plate increases significantly. This is PbSPbO at the lattice-active material interface.
! , H, SO, as a result of the local cell reaction, Pb
This is because SO4 is formed at the interface. Therefore, in order to improve the overdischarge storage performance, the generation of Pb5Oa may be suppressed, or even if Pb5Oa is generated, the conductivity at the lattice-active material interface may be maintained.

Conventionally, Sn is said to have an effect on overdischarge storage performance, and although the details of this effect are unknown, it is probably (
It is thought that Sn oxidizes to become Snug and exists at the lattice interface, and even if a resistive film is formed, SnO□ becomes a conductor and exists at the interface to enable charging.

From the above, it is considered that Sn acts effectively in practice if it exists on the surface of the current collector, and the doubuke method is considered to be very effective from this point of view. However, the treatment of soaking in water causes the film to collapse during chemical formation or charging, which poses many practical problems. Therefore, by heat-treating the soaked current collector, Sn is diffused into the current collector alloy matrix to prevent collapse of the alloy layer and to obtain a Sn-rich current collector that is effective against over-discharging. be able to.

Diffusion of Sn into the current collector alloy depends on the heat treatment temperature.

It is considered that the more the diffusion of Sn progresses inside the alloy layer, the more the collapse of the alloy layer on the surface of the current collector can be suppressed.

Therefore, in order to confirm the effect, an alloy plate heat-treated for 16 hours at different temperatures was oxidized at a constant current in a sulfuric acid solution, and the time until the alloy layer collapsed due to dipping was measured.

The results are shown in FIG. As the heat treatment temperature increases, the collapse time increases.Although heat treatment has an effect in the region of 170'C or less, a treatment time of 100 hours or more is required to have the same effect as that of heat treatment at 170'C or more. Heat treatment has a great effect on the collapse of the alloy layer due to soaking, as shown in the temperature above 0, which is not effective and cannot be used for practical purposes at temperatures below 120"C.

Next, an example will be described.

In order to examine the effect of post-heat-treated electrode plates on charging performance after over-discharging and leaving them, a 4Ah-2V battery was prepared using the above-mentioned electrode plates, and after the initial charge, 24 hours of constant resistance discharge were carried out in an open circuit state. It was left for 7 days. After being left standing, the battery was charged at a constant voltage of 2.45V, and the charging current was measured for 10 seconds, 30 seconds, and 60 seconds. The results are shown in FIG. Heat-treated product A has about twice as much current flowing as conventional product B, and untreated product C
is about 1.6 times. However, before over-discharge 10
When cycle charging and discharging are repeated (Figure 3) Untreated product C
is degraded to almost the same level as conventional product B, but heat-treated product A has almost no degradation.

Effects of the Invention As described above, the present invention has great industrial value, such as being able to have a great effect on over-discharge storage performance.

[Brief explanation of the drawing]

FIG. 1 is a curve diagram showing the relationship between treatment temperature and disintegration time when a soaked alloy plate is subjected to constant current oxidation, and t indicates the disintegration time of an untreated plate. FIGS. 2 and 3 are chargeability comparison curve charts after the initial charge and after 7 days of over-discharging after 10 cycles of charging and discharging.

Claims (1)

[Claims] A Pb-Ca alloy current collector that does not contain Sb is immersed in a molten Sn or Pb-Sn alloy bath to coat the surface with Sn or Pb-
A method for producing an electrode plate for a lead-acid battery, which comprises heat-treating the Sn alloy layer at 170° C. or higher for a predetermined period of time after forming the Sn alloy layer.