JPS62211872A - Sealed lead-acid battery - Google Patents

Abstract

PURPOSE:To prevent short circuit caused by decrease in electrolyte concentration in a battery which was allowed to stand after overdischarged, by forming a sealed lead-acid battery so that a theoretical capacity ratio of an electrolyte to a negative active material is a specified value or less. CONSTITUTION:In a sealed lead-acid battery in which most of the electrolyte is retained in a positive plate, a negative plate, and a porous separator, a theoretical capacity ratio of the electrolyte to a negative active material is specified to 0.75 or less, that is, the capacity of the electrolyte is reduced than that of the active material. when the battery was allowed to stand after overdischarged, SO4<2-> ions in the electrolyte react with the active material to produce PbSO4, and discharge is advanced, however, by reducing the capacity of the electrolyte, or the number of SO4<2-> ions, the advance of the discharge is prevented. Therefore, the dissolution of lead as Pb<2+> is retarded and short circuit caused by deposition of lead in charge can be prevented.

Description

[Detailed description of the invention] Industrial applications The present invention relates to improvements in sealed lead-acid batteries.

Conventional technology and its problems The most commonly used sealing method for lead-acid batteries is
This method allows the negative electrode to absorb oxygen gas generated from the positive electrode during charging. In this case, since the solubility of oxygen gas in dilute tin is very low, the above-mentioned sealing reaction will not occur if a sufficient amount of electrolyte exists between the electrodes.

Therefore, a structure (retainer type) in which only the separator is impregnated with electrolyte has been devised to reduce the leakage of electrolyte between the electrodes and facilitate the permeation of oxygen gas.

In such a battery, the electrolyte level is small, so when the battery is left to over-discharge, the electrolyte level becomes very low. In this case, the lower the sulfuric acid ratio I, the higher the solubility of lead 1iiIE acid, which is a discharge product, is eluted into the electrolytic solution and precipitated by charging. In the worst case, it may pass through the separator and come into contact with the opposite electrode, resulting in a short circuit.

Means for Solving the Problems The present invention is based on the theoretical capacity ratio of the electrolyte and the negative electrode active material (electrolyte volume f
By setting fi/negative electrode active material volume ff1) to 0.75 or less, that is, by configuring the element with a smaller electrolyte capacity than the active material capacity, the above-mentioned drawbacks can be eliminated. The present invention provides a sealed lead-acid battery that is not easily short-circuited even if left over-discharged.

Action When left to overdischarge, the 8042- ions in the electrolyte react with the active material to form Pb SOa, and the discharge progresses, but in the battery of the present invention, the electrolyte volume ffi, that is, the 804'-ion Since the number is small, discharge will not occur beyond a certain level. At that time, the resistance of the electrolyte increases and the terminal voltage shows a very small 1r1, but the discharge of the electrode plate itself has not progressed deeply, and the positive electrode plate remains at a noble potential and the negative electrode plate remains at a base potential. ing. Therefore, lead becomes F)b2+ and is less likely to dissolve. As a result, it is possible to prevent precipitation from occurring due to charging.

Example An embodiment according to the present invention will be described below.

A closed type battery with a structure in which most of the electrolyte is held in the positive and negative electrode plates and separators K) M? In a pond, the theoretical capacity ratio of the electrolyte and the negative electrode active material (electrolyte capacity/negative active material capacity) is X, and the theoretical capacity ratio of the positive and negative electrode active materials (positive electrode active material capacity/negative electrode active material volume ff1) is Y, 0.3<X
Batteries in the range <1.2.1.0<Y<1.8 were manufactured. For these batteries, after full charge, 10
ill that continued to short circuit for 3 weeks due to resistance of Ω/cell 2,45
V/t/L/T: 24 hours charging 1L, 0
．． A test was conducted in which a charging and discharging pattern was repeated in which discharge was performed until the voltage reached 5AF 1.7V/l. The results are shown in FIG. For batteries with X>0.8, a short circuit occurred after 1.2 cycles, but for batteries with X≦0.15, no short circuit occurred even after 5 cycles.

Effects of the Invention As described above, the sealed lead-acid battery of the present invention can prevent the occurrence of short circuits due to a decrease in the degree of electrolyte when left over-discharged, which is of great importance in the industrial field.

[Brief explanation of drawings]

Figure 1 shows the theoretical capacity ratio of the electrolyte and negative electrode active material (7! solution volume / negative electrode active material volume) and the theoretical capacity ratio of positive and negative active materials (positive electrode active material volume ffi / negative electrode active material volume). Material volume F!i)
This shows the relationship between the number of cycles in which yr118 occurred, and the number in O is y! The number of im cycles is shown, and the others indicate cases in which no short circuit occurred for 5 cycles or more.

Claims (1)

[Claims] 1. In a battery with a structure in which most of the electrolyte is absorbed and retained in the positive electrode plate, negative electrode plate, and porous separator, the theoretical capacity ratio of the electrolyte and the negative electrode active material (electrolyte capacity/negative electrode active material capacity) A sealed lead-acid battery with a value of 0.75 or less.