JP5995191B2 - Control valve type lead-acid battery and manufacturing method thereof - Google Patents

Description

  The present invention relates to a control valve type lead acid battery, and more particularly to a control valve type lead acid battery excellent in high rate discharge performance.

  In a control valve type lead-acid battery, an electrolytic solution is retained in a retaining liquid such as a retainer mat to eliminate a fluid electrolytic solution, and a sealed battery case equipped with a control valve is used. And the control valve type lead acid battery does not require rehydration. However, the control valve type lead-acid battery has a problem that the low-temperature high-rate discharge performance is insufficient because the supply of sulfate ions to the negative electrode active material is insufficient during high-rate discharge. The inventor examined improving the low-temperature high-rate discharge performance of the control valve type lead-acid battery by controlling the particle size of barium sulfate contained in the negative electrode active material.

  Related prior art is shown. Patent Document 1 (JPH08-236119A), Patent Document 2 (JP2003-36882A), and Patent Document 3 (JP2004-273305A) describe the average particle diameter of barium sulfate added to the negative electrode active material of a lead storage battery. Here, Patent Document 1 states that when the primary particle diameter is 1.0 μm or less, the negative electrode active material can be uniformly contracted and the charge / discharge life performance can be improved. Patent Document 2 states that, when barium sulfate having an average particle diameter of 0.5 μm or more is added to a control valve type lead storage battery, charge acceptability can be improved under use conditions with insufficient charge. Patent Document 3 states that when barium sulfate having an average particle diameter of 1 to 4 μm is added, the charge acceptability when deep discharge is frequently repeated can be improved.

JPH08-236119A JP2003-36882A JP2004-273305A

  The subject of this invention is improving the high rate discharge performance of a control valve type lead acid battery.

The present invention relates to a valve-regulated lead-acid battery having a negative electrode active material containing lead powder and barium sulfate, a positive electrode active material containing lead powder, and a liquid retaining liquid that holds an electrolytic solution.
The barium sulfate has a maximum secondary particle size of 10 μm or less , an average secondary particle size of 1.0 μm to 2.5 μm, an average primary particle size of 0.5 μm to 1.8 μm , and barium sulfate in the negative electrode active material. Content is 0.5 mass% or more, It is characterized by the above-mentioned.

  FIG. 3 shows the relationship between the maximum secondary particle size and the duration of high rate discharge. Here, the content of barium sulfate in the negative electrode active material was five types of 0.36 mass%, 0.40 mass%, 0.60 mass%, 1.00 mass%, and 1.40 mass%. When the maximum secondary particle size was increased with the same barium sulfate content, the duration of high rate discharge decreased. When the maximum secondary particle diameter was more than 10 μm, the duration of the high rate discharge did not increase even when the barium sulfate content was increased to 0.4 mass% or more. On the other hand, when the maximum secondary particle size was 10 μm or less, increasing the barium sulfate content also increased the duration of the high rate discharge and improved the high rate discharge performance.

  The maximum secondary particle diameter of barium sulfate in the negative electrode active material is measured as follows. The negative electrode plate is taken out from the fully charged lead acid battery, and sulfuric acid is removed by washing with water and drying. Next, the negative electrode plate is cut so that the cross section of the negative electrode active material appears, and barium sulfate particles are detected from the distribution of Ba atoms by EPMA (Electron Probe Micro Analysis) at five locations. The circle with the smallest diameter including the barium sulfate particles is taken as the maximum secondary particle diameter, and the maximum secondary particle diameter in five images is obtained. FIG. 4 shows how to obtain the secondary particle diameter. The diameter D of the smallest circle 4 containing the barium sulfate particles 2 is the secondary particle diameter. The barium sulfate content can be determined by, for example, ICP analysis.

In barium sulfate, secondary particles develop due to aggregation of primary particles. To produce barium sulfate with a small secondary particle size,
・ Large secondary particles are removed by sieving, cyclone, etc.
・ Suspend barium sulfate in water, etc., and destroy secondary particles by stirring, ultrasonic waves,
-Strengthen the kneading conditions during the production of the negative electrode paste, destroy the secondary particles by friction with lead powder,
Etc. are possible.

Preferably, the barium sulfate content in the negative electrode active material is preferably 0.6 mass% or more.
Further, the barium sulfate content in the negative electrode active material is preferably 2 mass% or less, more preferably 1.5 mass% or less. In the range including the upper limit and the lower limit, the barium sulfate content in the negative electrode active material is preferably 0.5 mass% or more and 2 mass% or less, more preferably 0.6 mass% or more and 1.5 mass% or less.

EPMA image of negative electrode plate of Example EPMA image of comparative negative electrode plate Characteristic chart showing the effect of the maximum secondary particle size of barium sulfate on the duration of low temperature high rate discharge Diagram explaining equivalent circle diameter

  Hereinafter, an optimum embodiment of the present invention will be described. In carrying out the present invention, the embodiments can be appropriately changed in accordance with common sense of those skilled in the art and disclosure of prior art.

  Barium sulfate, carbon black, and lignin were added to lead powder produced by the ball mill method, and kneaded with sulfuric acid to obtain a negative electrode active material paste. The negative electrode active material paste was filled in a Pb—Ca-based negative electrode grid and aged. A positive electrode active material paste prepared by adding sulfuric acid to lead powder produced by the ball mill method and kneading was filled in a Pb-Ca positive electrode grid and aged. The composition of the negative electrode active material is 0 to 1.40 mass% for barium sulfate, 0.5 mass% for carbon black, 0.2 mass% for lignin, and the rest is lead powder. Lead powder may be manufactured by the Burton pot method or the like, and the degree of oxidation of lead powder such as lead content is arbitrary. Furthermore, the kind and content of additives other than barium sulfate are arbitrary, and synthetic resin fibers and the like may be included.

  As for the particle size distribution of the barium sulfate used, four types of comparative examples and three types of examples are shown, and the particle size distribution is shown in Table 1 together with low-temperature high-rate discharge performance and oil absorption. All of the barium sulfates in the comparative examples are commercially available barium sulfate, and the barium sulfates in the examples are obtained by suspending commercially available barium sulfate in water and pulverizing it with a mill equipped with a pulverizing medium. Neither the commercially available barium sulfate nor the barium sulfate of the examples has a large difference between the average primary particle size and the average secondary particle size, and the difference is the maximum secondary particle size, which is as small as 9.3 μm to 3.6 μm in the examples. In the comparative example, it is as large as 11.5 μm to 25.9 μm. In the examples, the oil absorption is 14 to 16 ml / 100 g, and in the comparative examples, 12 to 13.5 ml / 100 g. The specific surface area is larger in the examples. The average primary particle diameter of barium sulfate was measured by a laser light scattering method, and the secondary particle diameter was obtained by observing barium sulfate with an electron microscope, and the equivalent circular diameter D shown in FIG. Then, the maximum secondary particle diameter was determined, and the average secondary particle diameter was determined such that 50% of the barium sulfate mass was equal to or greater than the average secondary particle diameter by integrating from the larger particle diameter to the smaller particle diameter.

  The negative electrode plate was sandwiched from both sides by a retainer mat, and the positive electrode plate was disposed outside the negative electrode plate, and was accommodated in a battery case equipped with a control valve in a state where pressure was applied. The electrode plate was five negative plates and six positive plates. The retainer mat may be changed to any liquid retaining liquid such as a sheet or granule obtained by gelling sulfuric acid with silica or the like, or a porous rubber sheet holding sulfuric acid. Sulfuric acid is injected into the battery case and absorbed by the retainer mat, the positive electrode plate and the negative electrode plate, and it is formed with a quantity of electricity of 770% of the 5-hour rate capacity. Two lead storage batteries were prepared for each type and content of barium sulfate.

  A constant current discharge of 150 A was performed at -15 ° C. until the terminal voltage of the battery reached 1.0 V, and the discharge duration at low temperature and high rate was measured. In addition, the negative electrode plate after charging was cut, EPMA images were obtained at five locations arbitrarily selected from the cross section, and the maximum secondary particle diameter of barium sulfate was measured by the equivalent circle diameter method of FIG. The maximum secondary particle size in Table 1 is a value of barium sulfate alone, but coincided with the maximum secondary particle size obtained from the EPMA image of the cross section of the negative electrode plate. The low-temperature high-rate discharge performance represents high-rate discharge performance, which is the performance at the start-up of an automobile engine or the like. Generally, when the low-temperature high-rate discharge performance is high, the high-rate discharge performance at room temperature is also high.

  1 shows an EPMA image of the negative electrode active material of Example 4 in Table 1, and FIG. 2 shows an EPMA image of the negative electrode active material of Comparative Example 7. The scale on the right side of the figure shows the concentration of Ba atoms, and dark particles with this value of 60% or more are secondary particles of barium sulfate. A bright region having a Ba concentration of 42 to 46% is bordered by a white line at the boundary of the barium sulfate particles, and a particle having a dark inside and a white outline is barium sulfate. For example, secondary particles of barium sulfate having a particle diameter exceeding 10 μm are seen in the lower left of FIG. 2, but no secondary particles of barium sulfate exceeding 10 μm are seen in FIG.

  Fig. 3 shows the duration of low-temperature, high-rate discharge. When the maximum secondary particle size is increased, the duration decreases, and when the maximum secondary particle size exceeds 10 µm, the duration is increased even if the barium sulfate content is increased. It turns out that it does not increase. On the other hand, when the maximum secondary particle diameter is 10 μm or less, the duration increases as the barium sulfate content increases, so that it can be seen that the low-temperature high-rate discharge performance can be improved. The results are shown in Table 1 together with the particle size distribution of barium sulfate.

  In Comparative Example 2 (maximum secondary particle diameter of barium sulfate 11.5 μm, content 0.40 mass%), a discharge duration of 116% was obtained. In Comparative Example, even if the barium sulfate content was increased to 1.40 mass%, The duration did not exceed 116%. Moreover, even when barium sulfate having a maximum secondary particle size of 10 μm or less was added, the results were not significantly different from the comparative examples up to a content of 0.40 mass%. However, when 0.60 mass% or more of barium sulfate having a maximum secondary particle size of 10 μm or less was contained, the discharge duration was 119% or more. For example, when the barium sulfate content is 1.40 mass%, it is 110% or less in the comparative example and 120% or more in the example.

  From FIG. 3 and Table 1, it can be seen that the low temperature high rate discharge performance is improved by setting the maximum secondary particle diameter of barium sulfate to 10 μm or less. In the examples, the maximum particle size was 9.3 μm, so the maximum secondary particle size is preferably 9.3 μm or less. The lower limit of the maximum secondary particle size is not important, but since barium sulfate having an average secondary particle size of less than 2.0 μm is used, the maximum secondary particle size is preferably 2.0 μm or more, and particularly preferably 3.0 μm or more. Further, the oil absorption of barium sulfate is preferably 14 ml / 100 g or more, particularly preferably 14 to 16 ml / 100 g. In addition, since the barium sulfate content in the negative electrode active material is good in a range centered on 0.6 to 1.4 mass%, 0.5 mass% or more, preferably 0.6 mass% or more, and preferably 2.0 mass% or less, Especially preferably, it is 1.5 mass% or less. The average primary particle size of barium sulfate is, for example, 0.5 μm to 1.8 μm, preferably 0.5 μm to 1.6 μm, and the average secondary particle size is, for example, 1.0 μm to 2.5 μm, preferably 1.0 μm to 2.2 μm. To do.

  In the examples, the high rate discharge performance can be improved by setting the maximum secondary particle diameter of barium sulfate to 10 μm or less and the barium sulfate content to 0.5 mass% or more.

2 Barium sulfate particles 4 The smallest circle

Claims (2)

In a valve-regulated lead-acid battery having a negative electrode active material containing lead powder and barium sulfate, a positive electrode active material containing lead powder, and a liquid retaining liquid that holds an electrolytic solution,
The barium sulfate has a maximum secondary particle size of 10 μm or less, an average secondary particle size of 1.0 μm to 2.5 μm, an average primary particle size of 0.5 μm to 1.8 μm, and barium sulfate in the negative electrode active material. A control valve type lead-acid battery, characterized in that the content is 0.5 mass% or more. A negative valve active material paste containing lead powder and barium sulfate is filled into a negative electrode grid, a positive electrode active material paste containing lead powder is filled into a positive electrode grid, and the electrolyte is held in a liquid retaining liquid. In the manufacturing method,
While making the barium sulfate content in the negative electrode active material 0.5 mass% or more,
By removing large secondary particles from barium sulfate or destroying secondary particles of barium sulfate, the distribution of the particle size of barium sulfate is 10 μm or less at the maximum secondary particle size and 1.0 μm as the average secondary particle size. A method for manufacturing a control valve type lead-acid battery, comprising performing a step of 2.5 μm or less and an average primary particle size of 0.5 μm or more and 1.8 μm or less.