JP2969888B2 - Lead storage battery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a lead storage battery having improved chargeability after being left in overdischarge.

[Prior Art] In general, when a lead storage battery is left for a long time or left after overdischarge, it becomes unable to be charged due to self-discharge. Therefore, in order to improve this drawback, a method of treating a lattice alloy or a lattice / active material interface of a lead-acid battery has been devised.
For example, the self-discharge is reduced by reducing the content of Sb in the lattice or using a Pb-Ca-based alloy that is an alloy containing no Sb.

In addition, as a measure for improving the overdischarge standing performance, it is known to increase the Sn content of the grid alloy, to perform Sn or Pb-Sn plating on the grid body surface, and to further heat-treat the plated grid. Have been.

[Problems to be Solved by the Invention] However, in order to improve the overdischarge leaving performance, the Sn content of the lattice alloy is increased, or Sn, P
The b-Sn plating or heat treatment thereof has the following disadvantages. That is, an increase in the Sn content of the lattice alloy significantly increases the cost. Further, in the plating treatment, the plating layer is eluted and collapsed during formation or charging, and the effect on the over-discharge standing performance is reduced, or the eluted Sn is dendrite deposited on the negative electrode plate and short-circuited with the positive electrode plate.
Although the heat treatment of plating is effective for the above-mentioned disadvantage, the Sn concentration in the depth direction of the lattice body surface is not uniform, and the Sn concentration in the very surface layer of the lattice body is still high. Therefore, Sn on the very surface is easily eluted, and the adhesion to the active material is deteriorated. Also, to prevent the elution of Sn, make the plating layer thinner,
When the heat treatment is performed, although the Sn concentration on the very surface of the lattice decreases, there is a disadvantage that the effect is not obtained on the overdischarge leaving performance.

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

[Operation] If a lead storage battery is left for a long time without being charged, self-discharge increases, and if left after deep discharge, charging becomes impossible. This is a non-reactive PbSO at the lattice / active material interface
_{This is because four} films are formed and the internal resistance of the battery is increased.
In particular, in the case of overdischarge, the internal resistance of only the positive electrode plate is significantly increased. This is because the lattice / active material interface at Pb, PbO _2, H ₂ SO result local cell reaction occurs by _4, t-PbO and PbSO ₄ film is formed on the interface. Therefore, in order to improve the overdischarge leaving performance, it is necessary to suppress the generation of PbSO ₄ , t-PbO,
Even if it is generated, the conductivity between the lattice and the active material may be maintained.

It is said that Sn has an effect on overdischarge leaving performance, and details of the effect are unknown, but it is probably Sn
Is oxidized to SnO ₂ and exists at the interface, so even if a resistive film is formed, SnO ₂ becomes a conductor and exists at the interface as a result, and as a result, it is not completely insulated by the resistive film, It is thought that charging is possible.

Therefore, as in the present invention, Sn and Pb are alternately stacked on the surface of the current collector mainly composed of Pb, and the surface layer is heat-treated to prevent the collapse of the surface layer and to reduce the surface layer to Pb. −Sn
Alloying can provide a current collector surface with a uniform Sn concentration. The Sn concentration on the surface of the current collector is not high, and Sn does not elute during formation or charging. Furthermore, the Pb layer of the surface layer and Sn
The advantage is that the Sn concentration on the current collector surface can be freely changed by changing the thickness ratio of the layers.

Example An example of the present invention will be described.

As shown in FIG. 1, Sn and Pb are alternately plated on the surface of a current collector body 1 made of a Pb-Ca-Sn alloy mainly composed of Pb to form a surface layer 2, and then heat-treated to form Pb. An electrode plate was prepared using the current collector on which the -Sn alloy layer 3 was formed, a lead storage battery was assembled, and an electrolytic solution to which Mg2 ⁺ was added was injected. A lead-acid battery of 1.2 Ah-2 V was used, and a 2.67 Ω constant-resistance discharge was performed for 24 hours. Then, the battery was allowed to stand for one month, and the charging performance (2.45 V, CV charge, 25 ° C.) was measured. For comparison, as a conventional product, the surface of a current collector made of a Pb-Ca-Sn alloy was
Heat-treated by plating (plated product), heat-treated after multi-layer plating of the present invention (multi-layered product) and Mg ²⁺ added to electrolyte (multi-layered + Mg ²⁺ added product) Was prepared and subjected to a test.

As a result, as shown in FIG. 2, the charging current of the multilayer plated product of the present invention was higher than that of the conventional plated product, and the charging current was further increased by using the multilayer plating and the addition of Mg ²⁺ . .

In addition, it can be seen that when 10 cycles of charge / discharge were performed before being left in over-discharge, the product of the present invention hardly deteriorated, but the conventional product had deteriorated.

[Effects of the Invention] As described above, according to the present invention, a lead-acid battery with improved reliability of overdischarge standing characteristics can be supplied, and its industrial value is very large.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view showing a current collector according to one embodiment of the present invention, and FIG. 2 is a comparative diagram showing charging characteristics after overdischarge. 1 is a current collector main body, 2 is a surface layer, 3 is a Pb-Sn alloy layer.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H01M 4/66

Claims (1)

(57) [Claims] 1. A lead battery comprising Sn and Pb alternately laminated on the surface of a current collector body mainly composed of Pb, and the surface layer is provided with a heat-treated current collector.