JP2007035496A - Chemical formation method of lead-acid storage battery container - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a chemical formation method of a lead storage battery container with production efficiency improved by preventing or restraining stratification of electrolyte solution and unevenness of a cathode active material. <P>SOLUTION: In chemical formation of the lead-acid storage battery container, charging is made until a charged electricity volume reaches 60 to 80% to a theoretical capacity of the cathode active material, and then current density is increased to generate gas and stir the electrolyte solution, so that a current density to be increased is to be 40 to 60 mA/cm<SP>2</SP>per unit area of a cathode plate, a charging electricity volume is to be 5 to 15% to a theoretical capacity of the cathode active material. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a battery case forming method for a lead storage battery in which production efficiency is improved by preventing or suppressing stratification of an electrolytic solution and non-uniformity of a positive electrode active material.

In lead-acid batteries, lead powder containing lead and lead monoxide as the main components is kneaded with water and dilute sulfuric acid to make a paste-like active material, and then the paste-like active material is filled in a current collector such as a lead alloy and held. The purpose of this work is to fill the active plate with the paste-like active material and hold it, for the purpose of growing the crystal of the active material, increasing the strength of the paste, increasing the chemical bonding force between the lattice surface and the active material, and removing moisture. After aging and drying, an electrode plate group is formed by alternately laminating unformed positive and negative electrode plates produced through an aging drying process with a separator interposed therebetween, and this electrode plate group is stored in a battery case. It is manufactured by heat-welding with a lid provided with a liquid injection port, injecting dilute sulfuric acid, which is an electrolytic solution, into this lead storage battery, energizing it, and forming a battery case.

In normal battery case formation, charging is performed at a relatively low current density, for example, about 10 mA / cm ² per unit area of the positive electrode plate in consideration of prevention of falling off of the filled and held pasty active material and formation efficiency. ing. When charging is performed at such a relatively low current density, the active material does not invert until the charged electric charge is close to 100% of the theoretical capacity of the positive electrode active material, and gas generation is small because the polarization is small. However, when the amount of charged electricity exceeds 100% of the theoretical capacity, polarization increases, gas starts to be generated vigorously, and the temperature rise also increases. In such a state, the chemical conversion efficiency decreases rapidly. Therefore, a general method is to suppress gas generation as much as possible by temporarily reducing the current after stopping or discharging and reducing the chemical conversion efficiency.

The dilute sulfuric acid injected at the time of battery cell formation reacts with the unformed positive and negative electrode active materials to produce lead sulfate, so that the concentration of the diluted dilute sulfuric acid decreases and the specific gravity decreases. When the battery case is formed from this state, sulfuric acid is discharged from the inside of the electrode plate. Since this sulfuric acid content is sufficiently higher than the surrounding dilute sulfuric acid, it sinks to the lower part of the battery and causes a phenomenon called stratification in which the sulfuric acid concentration differs between the upper and lower parts inside the battery case. As the amount of electricity charged relative to the theoretical capacity of the positive electrode active material is close to 100%, the generation of gas is small, so that stirring of sulfuric acid is difficult, and as the formation proceeds, the difference in sulfuric acid concentration between the upper and lower sides increases. If sulfuric acid having a high concentration is present around the bipolar plate, it is difficult for the lead sulfate dissolution reaction to proceed, resulting in a decrease in chemical conversion efficiency. If the sulfuric acid concentration difference between the upper part and the lower part in the battery is thus made, the chemical composition efficiency is different between the upper part and the lower part of the electrode plate, so that the composition of the electrode plate after the conversion becomes non-uniform. Particularly in the positive electrode, this difference is remarkable because the conversion efficiency is lower than that of the negative electrode. A battery composed of such a non-uniform electrode plate has a problem in that the self-discharge is large and the storage characteristics are remarkably inferior, and the initial performance is also low due to the presence of many undeveloped components.

Therefore, for example, in order to increase the formation current, in a battery case formation method for a lead storage battery using a corrosion-resistant lead alloy for the positive grid, a current not exceeding the gas generation potential is applied for 10 minutes or more before the battery formation. In order to suppress the non-uniformity of the sulfuric acid concentration that occurs during the charging of the electrolytic solution (Patent Document 1) and the electrolyte solution, after injecting the pole group into the battery case, the inside of the battery case is first depressurized to lower the concentration A method of injecting dilute sulfuric acid and then injecting high-concentration dilute sulfuric acid under atmospheric pressure and then forming a battery case, wherein the low-concentration dilute sulfuric acid has a volume of dilute sulfuric acid before the volume is injected. 60% to 90% and 35% by weight or more of the total sulfuric acid to which sulfuric acid is injected, and the high-concentration dilute sulfuric acid has a sulfuric acid concentration not exceeding 60% by weight (PTL 2). ) Is done.

JP 2004-356080 A JP 2002-352849 A

However, in the method of Patent Document 1 described above, it is possible to shorten the battery case formation time, but the current density during formation is about 20 mA / cm ² per unit area of the positive electrode plate, and is fixed at this value. Even if it forms, it cannot prevent or suppress the stratification of electrolyte solution and the nonuniformity of a positive electrode active material. Further, in the method of Patent Document 2, it is possible to prevent or suppress stratification of the electrolyte solution and non-uniformity of the positive electrode active material at the time of pouring, but it is completely considered to eliminate the non-uniformity caused by the chemical formation. However, this cannot be prevented or suppressed by chemical conversion at a conventional current density. Therefore, the methods of Patent Documents 1 and 2 require further improvement to meet the current market demand.

Under such circumstances, there is a demand for a battery case forming method for a lead-acid battery that improves production efficiency by preventing or suppressing stratification of the electrolyte and non-uniformity of the positive electrode active material.

The present invention is characterized in that, in the battery case formation of a lead storage battery, the amount of electricity charged with respect to the theoretical capacity of the positive electrode active material is charged to 60 to 80%, and then the current density is increased to generate gas and stir the electrolyte. It is what.

Further, the current density to be increased is 40 to 60 mA / cm ² per unit area of the positive electrode plate.

Moreover, the amount of charge when charging at a current density of 40 to 60 mA / cm ² is 5 to 15% of the theoretical capacity of the positive electrode active material.

  In the present invention, the amount of electricity charged to the theoretical capacity of the positive electrode active material is charged to 60 to 80%, and then the current density is increased to generate gas and stir the electrolytic solution, thereby stratifying the electrolytic solution and the positive electrode. Non-uniformization of the active material can be prevented or suppressed. When the amount of charged electricity is less than 60%, if gas is generated in this state, the active material may peel off because the chemical bonding force between the lattice and the active material interface and between the active materials is weak. Moreover, since sufficient lead sulfate remains in the active material, even if the electrolyte is once stirred by gas generation, the stratification phenomenon occurs again and the effect is weak. When the amount of charged electricity is larger than 80%, a considerable stratification phenomenon has already occurred in the storage battery, so the formation efficiency is lowered and the effect is small.

Also, the current density is set to 40 to 60 mA / cm ² because the lead storage battery has relatively good charging efficiency in the range of 60 to 80% of the charge electricity amount, and it is difficult for gas generation due to polarization to occur. ^{If the} current density is less than ² , the amount of gas generated is relatively small, and the effect of eliminating stratification is relatively small. On the other hand, if the current density is greater than 60 mA / cm ² , an excessive amount of gas is generated. Further, peeling or cracking between the lattice / active material interface and the active materials may occur, and the battery performance may be deteriorated.

In addition, by setting the amount of charge to be charged at a current density of 40 to 60 mA / cm ² to 5 to 15% of the theoretical capacity of the positive electrode active material, the battery performance is particularly deteriorated due to the temperature rise inside the storage battery during charging. It is possible to suppress and stir the electrolyte, and if the amount of charged electricity is less than 5%, it is not sufficient to stir the electrolyte, and the expected effect is small. On the other hand, if it is larger than 15%, it is sufficient for stirring the electrolytic solution, but the temperature rise inside the storage battery becomes large. The degree of temperature rise inside the storage battery is such that the greater the charging current and the longer the charging time, the greater the amount of heat generated by the temperature, and the temperature inside the storage battery rises rapidly. If the high temperature state continues during the formation of the battery case, there arises a problem that the battery performance is lowered.

As in the present invention, the amount of charge with respect to the theoretical capacity of the positive electrode active material is charged to 60 to 80%, and then the current density is increased to generate gas and stir the electrolyte, thereby temporarily polarizing. The gas is generated by increasing, and the electrolyte solution (sulfuric acid) can be stirred at a relatively early stage. By preventing upper and lower stratification, the local reduction in chemical formation efficiency is suppressed and the electrode plate has a uniform composition. Can be manufactured, and a battery having good storage characteristics and initial performance can be obtained. In addition, since the charging time for forming the battery case can be shortened, the production efficiency can be increased.

The electrode plate is made of a Pb-Ca-based or Pb-Ca-Sn-based lead alloy made of a paste-like active material obtained by kneading lead powder containing lead and lead monoxide as main components with water and dilute sulfuric acid. For the purpose of growing the active material crystals, increasing the strength of the paste, increasing the chemical bonding force between the lattice surface and the active material, removing moisture, etc. It is produced through the aging drying process. The unformed positive and negative electrode plates prepared in this way are alternately stacked with separators interposed therebetween to form an electrode plate group, the electrode plate group is housed in a battery case, and a lid provided with a liquid inlet and a heat After fusing and injecting dilute sulfuric acid, which is an electrolytic solution, into the battery case from the injection port, the storage battery is manufactured by charging and discharging in the chemical conversion step.

Four unformed positive electrode plates filled with 63.5 g of active material on a positive electrode grid substrate (height 108 mm, width 102 mm), and non-formed material filled with 53.0 g of active material on a negative electrode lattice substrate (height 109 mm, width 102 mm) Five negative electrode plates were alternately stacked via separators, and the positive electrode plates and the negative electrode plates were welded with straps to produce an electrode plate group. Then, the electrode plate group is housed in a battery case, a lid is applied to the battery case, and diluted sulfuric acid having a specific gravity of 1.28 is injected from a liquid injection port provided on the battery case cover, and a theoretical capacity of 58 Ah (rated capacity of 27 Ah) A 2V cell lead-acid battery was prepared. Thereafter, a battery case was formed in a 40 ° C. water tank. In addition, the specific gravity of the dilute sulfuric acid in the lead storage battery is set to a desired liquid specific gravity at the end of the formation of the battery case.

The energization conditions of the battery case formation are 20% to 100% of the theoretical capacity of the positive electrode active material as shown in Table 1 at a current density of 10 mA / cm ² per unit area of the positive electrode plate as the first charge (Invention 1). 2, after charging to the amount of charge in Comparative Examples 1 to 3), the amount of charge is 10% of the theoretical capacity of the cathode active material at a current density of 40 mA / cm ² per unit area of the cathode plate. Charging was performed, and charging was performed again at a current density of 10 mA / cm ² until the total amount of charge in the first charge was 120% of the theoretical capacity of the positive electrode active material.

Next, each charged lead-acid battery is discharged at a current density of 10 mA / cm ² per unit area of the positive electrode plate for an amount of electricity of 10% with respect to the theoretical capacity of the positive electrode active material. At a current density of 10 mA / cm ² per unit area, 100% of charge electricity was charged with respect to the theoretical capacity of the positive electrode active material, and the formation was completed. After the formation of the battery case, each 2V cell lead storage battery was disassembled, the positive electrode plate was taken out, washed and dried, and the amount of lead sulfate was measured on the upper and lower portions of the positive electrode plate. Table 2 shows the results of the content of lead sulfate per unit weight of the upper and lower unit weights of each 2V cell lead-acid battery. In addition, the measurement of the content rate of the amount of lead sulfate was calculated by composition analysis.

As shown in Table 2, the present invention 1 and 2 (charged electricity amount is 60 and 80%, respectively) are compared with Comparative Examples 1 to 3 (charged electricity amount is 20, 40 and 100%, respectively). It can be seen that the difference in composition is small and uniform formation is achieved. In Comparative Examples 1 to 3, it can be seen that the amount of lead sulfate in the lower portion of the positive electrode plate was large, and a relatively high concentration of sulfuric acid was distributed due to the stratification phenomenon.

Next, a 5-hour rate discharge capacity test was conducted under the conditions of a discharge current of 5.4 A and a final voltage of 1.75 V using the same lead storage battery of each 2 V cell. In addition, in order to see the difference in self-discharge during standing using the same lead storage battery of each 2V cell, first, as a low temperature high rate discharge test, a condition of a discharge current of 150 A and a final voltage of 1.0 V in an atmosphere of −15 ° C. Measured duration and voltage at 5 seconds, and left in a 40 ° C atmosphere for 4 weeks after full charge, and then conducted a low-temperature, high-rate discharge test again under the same conditions. The degree of storage was measured to confirm the storage characteristics. Table 3 shows the 5 hour rate discharge capacity and storage characteristics of each 2V cell lead-acid battery. The result is shown as the voltage storage rate.

As shown in Table 3, it can be seen that the present inventions 1 and 2 have better initial discharge characteristics than those of Comparative Examples 1 to 3, and further have better storage characteristics during standing. This result shows that the uniformity of the electrode plate composition and the battery performance are strongly related. As a reason why the performance of Comparative Examples 1 to 3 was inferior, Comparative Example 3 caused irreversible compositional non-uniformity by stratification with high-concentration sulfuric acid discharged from the electrode plate as the battery cell formation progressed. The effect is weak. In addition, when the amount of charge electricity is relatively shallow as in Comparative Examples 1 and 2, since the chemical bond between the active material and the lattice or the active material is still weak, the current is large enough to generate gas in such a state. When charged at a density, cracks and peeling of the active material occur, which is considered to have adversely affected. From these results, it is preferable to increase the current density and generate gas when the amount of charge is charged to 60 to 80%.

Next, in order to obtain a preferable range of the current density to be increased after charging up to 60 to 80% after starting the battery formation, a 2V cell lead-acid battery is produced in the same manner as in Example 1, Battery formation was performed in a 40 ° C. water bath. The energization conditions for the battery case formation are as follows. After charging to the charge capacity of 60% of the theoretical capacity of the positive electrode active material at a current density of 10 mA / cm ² per effective unit area of the positive electrode plate as the first charge, As shown in Table 4, charging for 10% of the charge electricity amount with respect to the theoretical capacity of the positive electrode active material at a current density of 30 to 70 mA / cm ² (present inventions 1 and 3 to 6) per effective unit area of the positive electrode plate. Thereafter, charging was performed again at a current density of 10 mA / cm ² until the total charge amount of the first charge became 120% of the theoretical capacity of the positive electrode active material. Thereafter, as in Example 1, the discharge was carried out for 10% of the electric capacity with respect to the theoretical capacity of the positive electrode active material at a current density of 10 mA / cm ² , and then the current density per unit area of the positive electrode plate was 10 mA / cm as the second charge. The amount of electricity charged for 100% of the theoretical capacity of the positive electrode active material was charged at cm ² to complete the formation. After completion of battery case formation, after completion of battery case formation, the lead storage battery of each 2V cell was disassembled in the same manner as in Example 1, the positive plate was taken out, washed and dried, and the amount of lead sulfate in the upper and lower portions of the positive plate was set. Measurements were made. The results are shown in Table 5.

As shown in Table 5, the present invention 1, 4 and 5 (current density, respectively 40,50,60mA / cm ²⁾ is compared with the present invention 3,6 (current density, respectively 30,70mA / cm ²⁾ positive It can be seen that the difference in composition between the top and bottom of the plate is small, and the formation is more uniform.

Next, a 5-hour rate discharge capacity test and storage characteristics were confirmed using the same lead storage battery of each 2V cell. The test was performed under the same conditions as in Example 1. Table 6 shows the results of discharge capacity and storage characteristics of each 2V cell lead-acid battery.

As shown in Table 6, it can be seen that the present inventions 1, 4 and 5 are particularly excellent in the initial discharge characteristics and the storage characteristics compared to the others. The third aspect of the present invention seems to be because the current density was small and gas generation was small and the stirring of the electrolyte (sulfuric acid) was slight. In the present invention 6, the duration storage rate and the 5th second voltage storage rate are not significantly different from those of the present inventions 1, 4 and 5, but the 5-hour rate discharge is lowered because the current density is large. It is considered that some peeling of the active material occurred.

In order to obtain a preferable amount of charge electricity at an increased current density, a lead-acid battery having a 2V cell was produced in the same manner as in Example 1, and a battery case was formed in a 40 ° C. water tank. The energization conditions for the battery case formation were as follows: the first charge was charged at a current density of 10 mA / cm ² per effective unit area of the positive electrode plate up to the theoretical capacity of the positive electrode active material up to 60% of charge electricity, and then the current density As shown in Table 7 at 40 mA / cm ² , the charge capacity was charged to 2.5% to 20% (Invention 1 and 7 to 10) with respect to the theoretical capacity of the positive electrode active material. Thereafter, charging was performed again at a current density of 10 mA / cm ² until the total charge amount of the first charge was 120% of the theoretical capacity of the positive electrode active material. Thereafter, discharging and second charging were performed in the same manner as in Example 1 to complete the formation. After the formation of the battery case, the lead storage battery of each 2V cell was disassembled in the same manner as in Example 1, the positive electrode plate was taken out, washed and dried, and the amount of lead sulfate in each of the upper and lower portions of the positive electrode plate was measured. The results are shown in Table 8.

As shown in Table 8, the present invention 1 and 8, 9 (charged electricity amount is 5.0, 10.0, 15.0%, respectively) are positive electrodes compared to the present invention 7 (charged electricity amount 2.5%). It can be seen that the difference in composition between the top and bottom of the plate is particularly small, and it is uniformly formed. In the invention 10 (charged electricity amount 20.0%), the storage battery temperature was very high as compared with other ones having a small difference in composition between the upper and lower sides of the positive electrode plate.

Next, a 5-hour rate discharge capacity test and a storage characteristic test were performed using the same lead storage battery of each 2V cell. The test was performed under the same conditions as in Example 1. Table 9 shows the results of discharge capacity and storage characteristics of each 2V cell lead-acid battery.

As shown in Table 9, it can be seen that the present inventions 1, 8 and 9 are particularly superior in initial discharge characteristics and storage characteristics as compared with the present inventions 7 and 10. In the invention 10, since the storage battery temperature became very high during the formation of the battery case (during charging), the characteristics were deteriorated depending on the temperature, and as a result, the characteristics were not particularly excellent.

Based on the above results, the amount of charge with respect to the theoretical capacity of the positive electrode active material is charged to 60 to 80%, and then the current density is increased to generate gas and stir the electrolyte to suppress stratification of the electrolyte. Thus, the composition can be made uniform above and below the electrode plate. Furthermore, the charging period can be shortened by increasing the charging density.
Furthermore, the current density to be increased is set to 40 to 60 mA / cm ² per unit area of the positive electrode plate, and the charge electricity amount at the increased current density is set to 5 to 15% with respect to the theoretical capacity of the positive electrode active material. It is possible to achieve more excellent effects.

Claims (3)

In a battery formation method for a lead-acid battery, the amount of charge with respect to the theoretical capacity of the positive electrode active material is charged to 60 to 80%, and then the current density is increased to generate gas and stir the electrolyte. A battery case formation method for lead-acid batteries. The battery case formation method for a lead storage battery according to claim 1, wherein the current density to be increased is 40 to 60 mA / cm ² per unit area of the positive electrode plate. 40～60MA / charged electricity quantity in the case of charging at a current density of cm ² is conductive container formation method of a lead-acid battery according to claim 2, characterized in that there 5-15% relative to the theoretical capacity of the positive electrode active material.