JPH01302661A - Lead acid battery and its manufacture - Google Patents

Abstract

PURPOSE:To enhance the rising characteristic of a lead acid battery equipped with a higher capacity when it is left in overdischarged condition for a certain period of time and also the restoring characteristic after self-discharging, by using an electrode plate, whose X-ray diffraction peak ratio of alpha-PbO2 to beta-PbO2 is specified, to the active substance of a surface layer and central layer. CONSTITUTION:After a lattice is filled with paste, it is immersed in sulfuric acid solution to turn its surface layer into PbSO4, and upon usual heat formation, this is subjected to chemical formation in neutral sulfate solution followed by specified processes to use an electrode plate, whose active substance in the surface layer has an X-ray diffraction peak ratio of alpha-PbO2 to beta-PbO2 is alpha/beta<=0.5 while that in the central layer is alpha/beta>0.5. In this type of electrode plate, the active substance on both surfaces has an increased porosity and is rich with beta-PbO2 to cause increase in the capacity, while the active substance in the central layer is rich with alpha-PbO2 and does not commit so much to electrochemical reaction, so that no PbSO4 or PbO are produced in the neighborhood of the lattice. This enhance the rising characteristic in charging after the battery turned into high capacity is left in overdischarged condition or after it is self- discharged.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention improves the self-discharge and charge recovery characteristics of high-capacity lead-acid batteries after being left overdischarged.

Conventional technology Conventionally, in order to improve the charge recovery characteristics of lead-acid batteries after being left for self-discharge or over-discharge, the electrode sheet metal was left in low-concentration sulfuric acid after chemical formation, or the battery was left at high temperature to improve the lattice recovery characteristics. α-PbO2, which is inert and conductive to charge/discharge reactions, was generated nearby.

That is, even in the discharge reaction, pbso, which is a high-resistance material, is not generated in the vicinity of the lattice, and during charging, a charging current flows to the active material through α-PbO2.

Furthermore, after impregnating the unformed positive electrode plate with a neutral sulfuric acid solution, it is chemically formed in an electrolytic solution mainly composed of dilute sulfuric acid, and in the early stage of chemical formation, the neutral electrolyte in the active material and the active material near the lattice are combined. The reaction produces .alpha.-PbO2, and then the sulfuric acid in the electrolyte diffuses to form highly reactive .beta.-PbO2 inside and on the surface of the electrode plate.

Therefore, this also provides the same effect as above.

Problems to be Solved by the Invention In general, positive electrode plates left over-discharged or self-discharged have the drawback of poor charging start-up properties due to the formation of a high-resistance material PBSO, a film, and a lower oxide PbO on the lattice interface. be. Therefore, by the method of the prior art described above, α-PbO2
However, since the generation is very small and partial, and sufficient evidence cannot be obtained, it cannot be said that the charging start-up performance is sufficiently good.

In addition, conventional methods require additional steps after chemical formation, which increases work time and costs, and when a battery is made to have a high capacity, the discharge generally progresses to the inside and stops charging.
However, it has the disadvantage that the performance is even worse.

Means to Solve All Problems The present invention has been made to solve the above problems.
After filling the grid with the paste, it is immersed in a sulfuric acid solution to convert the surface layer to PbSO4, then the continuous cable is aged, and then it is chemically formed in a neutral sulfate aqueous solution and undergoes the prescribed steps, etc. So, the active materials on the surface layer of the electrode plate are α-pbo and β-
The X-ray diffraction peak ratio of pbo is α/β-025'tl'
The present invention is unique in providing a lead-acid battery using electrode plates in which the active material in the center layer is fjXl'iα/#) 0.5.

Effects of the present invention: By having the above image, the following effects occur. After the grid is completely filled with paste, it is immediately immersed in sulfuric acid solution, and the following reaction occurs.

Pbo+H2So, -+pbso, + H, Oi: (
D Time t7) Reaction B Proceed inward from the electrode plate tf i and advance to 1/3 or more from the electrode plate surface. Next, normal aging is performed, followed by chemical formation in a neutral sulfate aqueous solution, and 1/3 of the active material (in this case, pbso4) is absorbed into the interior from the electrode surface to become active in electrochemical reactions. β-Pbo2
becomes.

Moreover, since this part is converted to Pb1)04 in the unformed electrode plate state, the active material expands in volume (after forming -1, Pbo2)
porosity increases. In addition, the remaining internal active material (pbo here) at the center 7r- has poor electrochemical reaction.
A highly conductive (χ-pbo) layer is formed.

These are the results obtained using these methods! The electrode plate is made of α-PbO active material with a thickness of 1/3 from the surface of the electrode plate to the inside.

(2θ-285°) and β-PbO, (2θ-254°)
The X-ray diffraction peak ratio of α/l is 0.5, and the remaining L/
:3 active material had α/'β) 0.5. In addition, α
The peak ratios of -PbQ and β-pbo are simply shown as the respective active material amount ratios.

Generally, the discharge reaction proceeds from the surface to the inside, and the active material utilization rate is about 20 to 40 inches. However, in the discharge reaction distribution, the reaction ends when the thickness (force) is increased inward from the electrode surface.Therefore, the thickness l inward from the electrode surface
If less than /3 β-pbo is produced in the surface layer, the discharge capacity will decrease.

In the electrode plate obtained as described above, the active material with a thickness of 1/3 or more from the electrode plate surface to the inside increases in porosity and β-p
Since it is bo, su, nochi, the capacity increases, but the active material in the inner central layer is rich in α-pbo2,
Because it does not participate much in electrochemical reactions, p
BSO and Pbo are not generated, and even in high-capacity lead-acid batteries, the charging start-up performance after over-discharging or self-discharging is improved.

Example An embodiment of the present invention will be described.

First, the lead alloy grid is completely filled with lead oxide paste (~, 1
The sample was immersed in a rnol/l sulfuric acid solution for 20 hours to cause the following reaction.

PbO+ H2So4 → PbSO44-1 (,0 At this time, the surface layer active material of 1/3 from the electrode plate surface is almost pbs
o4 was generated. Next, a complete aging process is carried out as usual, followed by a complete chemical conversion process in a 1 ml/l Na2SO4 solution.

In this way, the obtained electrode plate has the active material of the surface layer of 1/3 thickness remaining at α/β-025 inside the electrode plate surface 3L, and the active material of the center layer of 1/3 being α /β2 is 3.21.

Ta. FIG. 1 shows the charge start-up performance after overdischarging. Conventional product A in the figure is a lead-acid battery using a plate obtained by filling paste → aging → chemical formation and leaving it in sulfuric acid at a low concentration. Conventional product B is a lead-acid battery that uses paste filling → aging, then neutral This is a lead-acid battery that has been chemically formed in sulfuric acid after impregnating the electrode plates with a sulfuric acid solution.

The battery uses a 4Ah-4V type sealed lead-acid battery, 0.5
Discharge for 24 hours with 30 resistance (-1 then open circuit and leave in 250 l''C atmosphere for 1 month; limited flow at 4 co-tl ~ 1.2 A power, constant voltage charge of 4.9 V) 5. The charging current was measured when the battery was turned on.As can be seen from this, the product of the present invention has significantly improved charging start-up performance compared to the conventional products A and B.

Next, Figure 2 shows the recovery capacity ratio after self-discharge between the product of the present invention and conventional products A and B.
This is a comparison of the 5-hour rate capacity after leaving an Ah-type sealed lead-acid battery in an atmosphere of 60° C. for one month and setting the 5-hour rate capacity before discharge to 100 and after recovery charging. As described above, the product of the present invention has a much better capacity recovery property than the conventional products A and B.

Next, FIG. 3 shows the relationship between the thickness of the active material (α〃≦0.5) in the surface layer from the surface of the electrode plate to the inside after chemical formation and the battery capacity. The battery is a 4Ah-4V type sealed lead-acid battery, and the discharge conditions are ICA constant current discharge with a final voltage of 2.8.
It was discharged to ■. The ambient temperature is 25±1°C. From this, the capacitance decreases when the thickness is less than 1/3 from the surface of the electrode plate to the inside, but it shows a constant value above that.

FIG. 4 shows the capacity of the product of the present invention and conventional products A and B at each discharge current. The battery used was a 4A) I-4V type sealed lead-acid battery, the ambient temperature was 25±1° C., and the end-of-discharge voltage was 2.8V. As is clear from FIG. 4, the discharge duration of the product of the present invention is longer than that of conventional products A and B, which is particularly noticeable in high rate discharge.

FIG. 5 is a comparison diagram of the cycle life characteristics of the product of the present invention and conventional products A and B. All batteries are 4Ah-4V type sealed lead-acid batteries, and the charging conditions are 4.9V constant voltage charging at an ambient temperature of 25±1℃, a limited current of 1.2 people, and a charging time of 4 hours. be. Further, the discharge conditions are constant current discharge of 4A and discharge to a final voltage of 2.8V.

As shown in the figure, it can be seen that the product of the present invention has a high capacity and a long life compared to the conventional products A and B.

Effects of the Invention As described above, according to the present invention, even in a lead-acid battery with a high capacity, the start-up performance after over-discharging and the recovery performance after self-discharge are improved.

[Brief explanation of the drawing]

Figure 1 is a characteristic diagram comparing the performance of charged standing soil after overdischarging, Figure 2 is a characteristic diagram comparing self-discharge performance, and Figure 3 is a graph showing the active material of the electrode plate surface layer after chemical formation (α/β≦0 .5) is a curve diagram showing the relationship between thickness and battery capacity, Figure 4 is a comparative characteristic diagram of the duration of each discharge flow, and Figure 5 is a comparative characteristic diagram of cycle life.

Claims (1)

[Claims] 1. The active materials of the surface layer of the electrode plate are α-PbO_2 and β-Pb
A lead-acid battery characterized in that the X-ray diffraction peak ratio of O_2 is α/β≦0.5, and the active material in the center layer is an electrode plate in which α/β>0.5. 2. After filling the grid with the paste, it is immersed in a sulfuric acid solution to convert the surface layer of the electrode plate into PbSO_4, then subjected to normal aging, followed by chemical conversion in a neutral sulfate aqueous solution and the prescribed process. A method for manufacturing lead-acid batteries obtained through the process.