JPH04137462A - Manufacture of lead storage battery plate - Google Patents

Abstract

PURPOSE:To obtain a lead storage battery having high electric capacity, not being in need of a processing vessel being exclusive for acid dipping by manufacturing a lead storage battery plate by forming an active material layer in the first energizing process and a stopping energizing process and the second energizing process. CONSTITUTION:In the first energizing process an unformed plate is energized until concentration of sulfuric acid solution becomes as much concentration as being necessary for acid dipping and the energizing is stopped. In the stopping energizing process after that, the unformed plate is left in the sulfuric acid solution under a stopping energizing condition until the acid dipping is completed. And in the last second energizing process, after the stopping energizing process the unformed plate is energized until unformed active material is formed. That is, as alpha-type lead dioxide is made by the second energizing process, a dense active material layer is formed near the boundary face of a grid body, and the left as over-discharged characteristic of a lead storage battery is improved by the effect of the acid dipping. Thereby the acid dipping can be performed without needing an exclusive processing vessel for the acid dipping, and further charging time can be shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for manufacturing an electrode plate for a lead-acid battery, and particularly to a method for chemically forming an unformed active material layer.

[Prior art] In the conventional method for manufacturing electrode plates for lead-acid batteries, after chemically forming an unformed active material layer, the electrode plate after chemical formation is immersed in dilute sulfuric acid of a predetermined concentration for a certain period of time. The called process is being performed. When this acid immersion is performed, the chemically formed active material (lead dioxide) and the lead (Pb) of the lattice body as a current collecting base react with sulfuric acid, and lead sulfate is formed at the interface between the lattice body and the active material. (P
bSO4) is generated. When this electrode plate is charged, the generated lead sulfate changes to α-type lead dioxide. Alpha-type lead dioxide has a dense structure and is relatively inert, so it inhibits the diffusion of sulfate ions into the lattice even if a lead-acid battery with acid-soaked plates is left over-discharged. be able to. Therefore, it is possible to prevent the lead in the grid from becoming lead sulfate, which is a nonconductor, and the overdischarge performance of the lead acid battery is improved.

[Problems to be Solved by the Invention] There are cases in which chemical conversion is carried out using a dedicated chemical conversion treatment tank, and there is a case in which chemical conversion is carried out using a dedicated chemical conversion treatment tank, and there is a case in which chemical conversion is carried out with the electrode plate group housed in the battery case. And acid soaking requires a lower concentration of dilute sulfuric acid than is needed to initiate the formation. Therefore, when using a dedicated chemical conversion treatment tank for chemical conversion, a dilute sulfuric acid tank containing dilute sulfuric acid for acid immersion is required outside the chemical conversion treatment tank, and lead sulfate generated during acid immersion is
Since it requires recharging in order to change to type lead dioxide, there is a problem that it requires large equipment and long processing time, and there is also the problem that it is difficult to reach the initial capacity.

In addition, in the latter case, the concentration of sulfuric acid in the container after completion of the formation is higher than the concentration of dilute sulfuric acid required for acid immersion. Therefore, if the chemically formed battery case is simply left in the battery case, the corrosion reaction will not proceed at the interface between the lattice body and the active material, and acid immersion will take a considerable amount of time. It was difficult to introduce acid immersion to improve discharge performance.

[Means for Solving the Problems] The present invention solves the above problems by introducing acid immersion during the chemical conversion process. Therefore, in the present invention, an unformed electrode plate having an unformed active material layer on a current collecting base is immersed in a sulfuric acid solution,
A method for manufacturing a lead-acid battery plate by energizing the plate to chemically form an unformed active material layer, comprising a first energizing step, a energizing stop step, and a second energizing step. do.

In the first energization step, the unformed electrode plate is energized until the concentration of the sulfuric acid solution reaches the concentration required for acid immersion, and then the energization is stopped. In the subsequent energization stop step, the unformed electrode plate is left in the sulfuric acid solution with the energization stopped for a period of time until the acid immersion is completed. In the final second energization step, after the energization stop step, the unformed electrode plate is energized until the unformed active material is chemically formed.

In the invention of claim 2, in the first energization step of the invention of claim 1, the unformed active material is energized until 10 to 20% of the theoretical amount of electricity is applied, and the energization stop time in the energization stop step is 20 hours or more.

[Operation] The first energization step reduces the concentration of the sulfuric acid solution to the concentration required for acid immersion. During formation, conversion of the unformed active material layer into an active material progresses from the periphery of the lattice body serving as a current collecting base. Therefore, at the time when the first energization step is completed, lead dioxide conversion has progressed near the interface between the unformed active material layer of the positive electrode plate and the lattice body. Note that the area away from the lattice body (the surface area of the electrode plate) has not yet been converted into an active material, and the unformed active material layer reacts with the sulfuric acid content in the electrolyte.
Sulfate formation progresses in a part of the unformed active material layer, and the specific gravity of the sulfuric acid solution decreases. In the present invention, in the first energization process, when the specific gravity of the sulfuric acid solution falls within the concentration range required for acid immersion, the energization is stopped and the electrode plate is left in the sulfuric acid solution until the acid immersion is completed. (Electrification stop step), acid immersion is performed in the middle of the chemical conversion step. In this energization stop step, acid immersion is performed. During acid immersion, the unformed active material on the surface side of the electrode plate reacts with sulfuric acid in the electrolyte to become lead sulfate, causing volumetric expansion of the active material layer. After the energization stop step, a second energization step is performed to restart the chemical formation.
Lead dioxide is produced at the anode, and lead is produced at the anode, both of which cause volumetric contraction.

When contraction occurs after expansion, sufficient pores (porosity) necessary for discharge are obtained in the active material layer, and the discharge capacity increases.

The lead dioxide generated near the interface with the grid body during the first energization process becomes lead sulfate through acid immersion during the energization stop process, and this lead sulfate becomes α-type lead dioxide during the second energization process. Therefore, a dense active material layer is formed near the interface with the lattice body, and the overdischarge performance of the lead-acid battery is improved due to the effect of acid immersion described above. As described above, according to the first aspect of the invention, an electrode plate for obtaining a lead-acid battery with a high capacity can be manufactured without requiring a treatment bath exclusively for acid immersion. Moreover, since the acid immersion treatment is performed during the chemical conversion treatment, the lead sulfate formed by the acid immersion can be converted into lead dioxide by the charging for the chemical conversion, which is different from the conventional charging for the chemical formation after the acid immersion. There is no need to perform separate recharging, and the charging time can be shortened.

Further, as in the invention of claim 2, in the first energization step, the unformed active material is energized until 10 to 20% of the theoretical amount of electricity is applied, and the energization stop time in the energization stop step is 2.
When the time is 0 hours or more, a lead-acid battery with even higher over-discharge storage performance and higher discharge capacity can be obtained.

[Example] An embodiment of the present invention will be described in detail with reference to the drawings.

In the example, first, an active material paste is applied to a grid of an appropriate shape and dried to produce an unformed electrode plate having an unformed active material layer. Then, the unformed electrode plate is immersed in a chemical conversion tank containing a sulfuric acid solution until the unformed active material layer is charged with 10 to 20% of the theoretical amount of electricity, that is, 10 to 20% of the unformed active material layer. The concentration of the sulfuric acid solution in the chemical conversion treatment tank is reduced to the concentration required for acid immersion by applying electricity until % is converted into an active material. Next, the energization is stopped, and the electrode plate is immersed in this chemical conversion treatment bath for 20 hours or more to perform the energization stopping step. Thereafter, power supply to the electrode plate is restarted, and the unformed active material layer is chemically formed.

(Example 1) A 2Ah-12V type sealed lead-acid battery was manufactured using a lead-acid battery plate manufactured by the method of the present invention and a plate whose energization time and energization-stop time were made different from those of the present invention. After manufacturing, various tests were conducted to investigate the overdischarge characteristics of a battery using the electrode plate manufactured by the manufacturing method of the present invention.

The test was conducted as follows.

First, a 10Ω resistor was connected to each test sealed lead-acid battery, over-discharged by constant resistance discharge for 24 hours, the resistor was removed, and the battery was left at 25° C. for 7 days.

Next, constant voltage charging was performed at 2.45 V/cell, and the charging time until the current of each sealed lead acid battery reached 100 mA was measured to examine overdischarge performance.

In Figure 1, the energization stop time in the energization stop step is 20 hours, and the amount of electricity applied in the first energization step is 0 to 40 hours.
Each lead-acid battery using electrode plates changed in the range of 0% was left under the above overdischarge conditions and then charged, and the charge amount and current applied in the first energization process were 100 m
It is a figure which showed the relationship with the charging time until it reaches A.

The horizontal axis of this figure shows the amount of charge, and the vertical axis shows the charging time. According to this figure, even if left over-discharged, the time it takes to reach 100 mA is the shortest when charging a lead-acid battery with the amount of charge applied in the first energization step being 10% or more. , it can be seen that the charging performance is good.

Figure 2 shows that each lead-acid battery using a plate was left to over-discharge, with the amount of electricity applied in the first energization step being 10%, and the energization stop time in the energization stop step being varied in the range of 0 to 100 hours. Regarding the battery, the energization stop time and current are 100mA
It is a figure which showed the relationship with the charging time until reaching. The horizontal axis of this figure shows the energization stop time, and the vertical axis shows the charging time. From this figure, it can be seen that the battery whose energization stop time is 20 hours or more has the best chargeability.

Fig. 3 shows the amount of electricity applied in the first energization step from 0 to 400, assuming that the energization stop time in the energization stop step is 20 hours.
It shows the results of measuring the discharge capacity of each lead-acid battery using electrode plates changed in a range of %. In FIG. 3, the horizontal axis shows the charge amount, and the vertical axis shows the discharge capacity ratio of each lead-acid battery when the discharge capacity of a lead-acid battery with a charge charge of 30% is 100. From this figure, it can be seen that when the amount of electricity applied in the first energization step exceeds 20%, the discharge capacity decreases rapidly, and when the amount of electricity applied exceeds 30%, the discharge capacity gradually decreases. Therefore, it can be seen that the discharge performance of the lead-acid battery improves when the amount of charge is set to 20% or less.

From Figures 1 to 3, the amount of electricity applied in the first energization step is 1.
It can be seen that lead-acid batteries with a charge ratio of 0 to 20% and a energization stop time of 20 hours or more have good charging performance and discharging performance after being left over-discharged.

(Example 2) As Example 2, an electrode plate for a lead-acid battery was manufactured by the method described below.

First, an unchemically formed active material layer is formed on a lattice body that forms a current collecting substrate to create an unformed electrode plate, and the unformed electrode plate is assembled through a separator made of fine glass fibers to form an electrode plate group. I made this, inserted it into a battery, and then poured dilute sulfuric acid into the battery. The dilute sulfuric acid injected had a specific gravity such that the specific gravity of the sulfuric acid after forming the battery was the same as that of sulfuric acid normally used in batteries.

After injecting dilute sulfuric acid, the container was chemically formed in the same manner as in Example 1 by inserting an acid immersion treatment during the chemical formation. Note that the test conditions were the same as those of Example 1.

Next, a 2Ah-12V type sealed lead-acid battery was manufactured, which was equipped with a lead-acid battery plate manufactured according to the present invention and a plate whose conduction time and de-energization time were different from those of the present invention. Tests were conducted to examine the overdischarge characteristics of batteries using electrode plates manufactured by the method of the present invention. The test method was the same as that used in Example 1.

Figure 4 shows the amount of electricity charged in the first energization process when the energization stop time in the energization stop process is 20 hours to approximately 400%.
When each lead-acid battery using electrode plates manufactured with different electrodes within the range of
It is a figure showing the relationship with the time until it reaches 0 mA. The horizontal axis of this figure shows the amount of charge, and the vertical axis shows the charging time. From this figure, when charging a lead-acid battery with a charge amount of 10% to 20% in the first energization step, 100
It can be seen that the time to reach mA is the shortest, and the charging performance is excellent even when left over-discharged.

Figure 5 shows the energization stop time of each lead-acid battery using a plate in which the energization stop time in the energization stop step was varied in the range of 0 to 100 hours, with the amount of electricity applied in the first energization step being 10%. FIG. 3 is a diagram showing the relationship between the charging time and the charging time in the above experiment.

The horizontal axis of this figure shows the energization stop time, and the vertical axis shows the charging time. From this figure, it can be seen that batteries with a energization stop time of 20 hours or more have excellent chargeability even when left over-discharged.

Next, the discharge capacity of each lead-acid battery was measured using electrode plates in which the energization stop time in the energization stop step was 20 hours, and the amount of electricity applied in the first energization step was varied in the range of 0 to about 400%. . Figure 6 shows the amount of charge on the horizontal axis and the amount of charge 3 on the vertical axis.
The discharge capacity ratio of each lead-acid battery is shown when the discharge capacity of a 0% lead-acid battery is set to 100. From this figure, it can be seen that lead-acid batteries with a charge amount of 20% or less in the first energization step have good discharge performance.

As described above, it can be seen that even when the method of the present invention is used to manufacture electrode plates for lead-acid batteries through container formation, the over-discharge performance of lead-acid batteries can be improved.

[Effects of the Invention] According to the invention of claim 1, acid immersion can be performed without requiring a dedicated treatment tank for acid immersion, and the charging time can be shortened. In addition, acid immersion can also be performed by container formation, and the electrode plates for lead-acid batteries, which are necessary for producing lead-acid batteries with high overdischarge performance and high discharge capacity, can be easily manufactured.

According to the invention of claim 2, in the first energization step, the unformed active material is energized until 10 to 20% of the theoretical amount of electricity is applied, and the energization stop time in the energization stop step is 20%.
By making it more than 1 hour, it is possible to manufacture a lead acid battery plate necessary for producing a lead acid battery with high overdischarge storage performance and high discharge capacity.

[Brief explanation of drawings]

Figure 1 is a diagram showing the relationship between the amount of electricity applied in the first energization step and the overdischarge performance of a lead-acid battery using a plate manufactured with the amount of electricity applied, and Figure 2 is a diagram showing the relationship between the energization stop time in the energization stop process and the overdischarge storage performance of a lead-acid battery using a plate manufactured during the energization stop time. FIG. 4 is a diagram showing the relationship between the amount of electricity applied and the discharge capacity of a lead-acid battery using a plate manufactured with the amount of electricity applied, and FIG. 4 shows the amount of electricity applied in the first energization process and This is a diagram showing the relationship between the over-discharge and storage performance of lead-acid batteries using electrode plates manufactured with the specified charge amount by the container chemical process, and Figure 5 shows the relationship between the energization stop time in the energization stop process and the charge applied by the container chemical process. This is a diagram showing the relationship between overdischarge of a lead-acid battery using electrode plates manufactured during the energization stop time and the performance of the electrical device. It is a figure showing the relationship with the discharge capacity of a lead-acid battery using the electrode plate manufactured by chemical formation with the said charge amount. Agent: Hidetoshi Matsumoto, patent attorney. and. (1 other person) 'su ゝ fig. fig.

Claims (2)

[Claims] (1) An unformed electrode plate having an unformed active material layer on a current collecting substrate is immersed in a sulfuric acid solution, and electricity is applied to the unformed electrode plate to chemically form the unformed active material layer. A first energization step of energizing the unformed electrode plate until the concentration of the sulfuric acid solution reaches the concentration required for acid immersion and then stopping the energization, and acid immersion. a energization stopping step of leaving the unformed electrode plate in the sulfuric acid solution with the energization stopped for a period of time until the energization is completed; A method for manufacturing a lead-acid battery plate, which comprises a second energization step of energizing the plate. (2) In the first energization step, energization is performed until the unformed active material is charged with 10 to 20% of the theoretical amount of electricity, and the energization stop time in the energization stop step is 20 hours or more. The method for manufacturing a lead-acid battery electrode plate according to claim 1.