JPH04141955A - Lead storage battery - Google Patents

Abstract

PURPOSE:To improve left over-discharged characteristics by laminating Sn and Pb alternately on a surface of a collector body being mainly made of Pb and heat-treating its surface layer and forming the collector. CONSTITUTION:Sn and Pb are alternately laminated on a surface of a collector body 1 of mainly Pb and its surface layer 2 is heat-treated and the collector is formed. That is, after the surface layer 2 is formed by alternate plating of Sn and Pb on the surface of the collector body 1 made of Pb-Ca-Sn alloy, in which Pb is a main component, a plate being made using the collector, on which a Pb-Sn alloy 3 layer is formed by heat treatment, a lead storage battery is assembled and electrolyte being added by Mg<2+> is poured. In this case charging current increases when both laminating plating and Mg<2+> addition are used. Sn and Pb being laminated alternately on the surface of the collector being mainly made of Pb and the surface layer being heat-treated, destruction of the surface layer is prevented, and such collector surface as being uniform in Sn concentration can be obtained by forming the surface into Pb-Sn alloy. Thereby it is possible to obtain a lead storage battery which has improved in reliability of left over-discharged characteristics.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a lead-acid battery that has improved chargeability after being left over-discharged.

[Conventional Technique #i] Generally, if a lead-acid battery is left unused for a long period of time or left over-discharged, it will become unchargeable due to self-discharge. Therefore, in order to improve this drawback, conventional efforts have been made to treat the lattice alloy and the lattice/active material interface of lead-acid batteries. For example, self-discharge is reduced by reducing the sb content of the lattice or by using a P b -Ca-based alloy that does not contain sb.

In addition, as a measure to improve overdischarge storage performance, increasing the Sn content of the lattice alloy and adding Sn to the lattice surface
Alternatively, it is known to perform Pb-8n plating and to heat-treat the plating lattice.

[Problems to be Solved by the Invention] However, in order to improve the overdischarge performance, it is necessary to increase the Sn content of the lattice alloy or to add Sn to the surface of the lattice.
, Pb-8n plating or heat treating it has the following drawbacks. That is, an increase in the Sn content of the lattice alloy significantly increases the cost. Furthermore, in the plating process, the plating layer dissolves and collapses during chemical formation or charging, reducing the effect on overdischarge performance, or the eluted Sn precipitates as dendrites on the negative electrode plate, causing a short circuit with the positive electrode plate. Although the plating heat treatment is effective for the above-mentioned drawbacks, the Sn concentration in the depth direction of the surface of the lattice body is non-uniform, and the Sn concentration in the very surface layer of the lattice body is still high.

Therefore, this very surface Sn is easily eluted, resulting in poor adhesion to the active material. Furthermore, if the plating layer is thinned and heat treated to prevent the elution of Sn, the Sn concentration at the very surface of the lattice body will be reduced, but there is a drawback that no effect will be obtained on the overdischarge storage performance.

[Means for Solving the Problems] In order to solve the above problems, Sn and Pb are alternately laminated on the surface of a current collector body mainly composed of Pb, and the surface layer is heat-treated to provide a current collector. It is characterized by:

[Function] If a lead-acid battery is left uncharged for a long period of time, self-discharge will increase, and if left after deep discharge, it will become unchargeable. This is due to non-reactive PbS at the lattice/active material interface.
This is because an O4 film is formed and the internal resistance of the battery increases. In particular, when left overdischarged, the internal resistance of only the positive electrode plate increases significantly. At the lattice/active material interface, Pb, Pbo□,
As a result of the local cell reaction caused by H2SO4, t-Pb
This is because a film of O and Pbso is formed at the interface.

Therefore, in order to improve overdischarge storage performance, Pbso,
, t-Pbo may be suppressed from being produced, or even if t-Pbo is produced, the conductivity of the lattice/active material may be maintained.

Sn is said to have an effect on over-discharge storage performance, and although the details of this effect are unknown, it is probably <S
Since n oxidizes to become S n Oz and exists at the interface, even if a resistive film is formed, Sn○ becomes a conductor and exists at the interface, and as a result, it is completely insulated by the resistive film. This is thought to enable charging without being interrupted.

Therefore, as in the present invention, Sn and Pb are alternately laminated on the surface of a current collector mainly composed of Pb, and the surface layer is heat-treated to prevent the collapse of the surface layer and to replace the surface layer with Pb.
By forming a b-Sn alloy, it is possible to obtain a current collector surface with a uniform Sn concentration. The Sn concentration on the surface of this current collector is not high;
Sn does not elute during formation or charging. Furthermore, it has the advantage that the Sn concentration on the surface of the current collector can be freely changed by changing the thickness ratio of the Pb layer and the Sn layer of the surface layer.

[Example code] An embodiment of the present invention will be described.

As shown in Figure 1, Pb-(a-
After forming a surface layer 2 by alternately plating Sn and Pb on the surface of the current collector main body 1 made of an Sn alloy, it is heat-treated to form a Pb layer.
A lead-acid battery was assembled by creating an electrode plate using the current collector on which the b-Sn alloy layer 3 was formed, and an electrolytic solution containing Mg"u was injected. The lead-acid battery had a power of 1.2A h -2V (7) 2,67 Q constant resistance discharge for 24 hours, then leave it for one month, and check the charging performance at that time (2,45 V,
CV charging, 25°C) was measured. For comparison, as conventional products, Pb was heat-treated after lamination plating of the present invention (multilayer plating product), and one with Mg2''! added to the electrolyte (
A laminated plating + Mg additive product) was prepared and used for testing.

As a result, as shown in FIG. 2, the charging current flowed more in the laminated plated product of the present invention than in the conventional plated product, and the charging current was further increased by using the laminated plating together with Mgl'' addition.

Furthermore, it can be seen that when the product of the present invention was charged and discharged for 10 cycles before being allowed to over-discharge, there was almost no deterioration, whereas the conventional product was deteriorated.

[Effects of the Invention] As described above, according to the present invention, a lead-acid battery with improved reliability of over-discharge characteristics can be provided. The cross-sectional view and FIG. 2 are comparative diagrams showing charging characteristics after being left to over-discharge.

1 is the current collector main body, 2 is the surface layer, and 3 is the Pb-Sn alloy layer.

Claims (1)

[Claims] Sn and Pb are added to the surface of the current collector body, which is mainly composed of Pb.
1. A lead battery comprising a current collector in which the surface layers are heat-treated.