JPH0384860A - Manufacture of paste for lead storage battery - Google Patents

Abstract

PURPOSE:To resolve the problem to reduce the service life property on the contrary although the efficiency of transformation charging is improved, by selecting the mean diameter of red lead to add to lead powder whose mean particle diameter is from 4mum to 7mum, less than that of the lead powder. CONSTITUTION:By making the mean particle diameter of a red lead to add to a lead powder less than the mean particle diameter from 4mum to 7mum of the lead powder generally used, the appearent density of a paste after the kneading is made higher. As a result, not only the combining force of the active substance each other is increased, but also an early softening fall oft is prevented. And more favorably, 50wt.% or more of the total particle amount of the red lead to add is made less than the lead powder in the mean particle diameter. Consequently, the transformation charging efficiency when the red lead is added is improved, and the problem of service life reduction owing to the early softening fall off can be solved by selecting the combination of the mean particle diameter of the red lead to add and that of the lead powder.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a method for producing paste for lead-acid batteries, and in particular, to improve the efficiency of chemical charging of paste-type electrode plates and the life characteristics of lead-acid batteries. be.

(2) Conventional technology Lead-acid batteries generally consist of lead powder, water and sulfuric acid, which are partially oxidized lead, and require short fibers such as resin, fine carbon powder, organic additives, etc. A paste-type electrode in which the paste obtained by mixing is applied to a continuous porous material such as a cast grid or expanded metal, and is formed into the shape of an electrode plate as necessary and dried to form an electrode plate. Many boards are used.

This electrode plate is further combined with a separator to form an electrode plate group, and after being incorporated into a battery case, dilute sulfuric acid is added and chemically charged, or by being incorporated after chemically charging, the battery function is imparted.

Problems to be Solved by the Invention During this chemical charging stage, especially when a positive electrode plate is made of a paste made of only lead powder without the addition of red lead, chemical formation occurs due to the nonconducting layer produced in the initial stage of chemical formation. Charging efficiency decreases. Therefore, in order to avoid the loss of power and time caused by this, a technique is known in which a high-level lead oxide called red lead, ie, pb3o4, is added. However, although the addition of red lead improves the efficiency of chemical charging, on the other hand, the bonding force between the active materials is weak, so the active materials tend to soften and fall off early, reducing the lifespan. It has not been put into practical use.

Means for Solving the Problems The present invention is intended to solve the above-mentioned problems, and as a specific means, red lead is added to lead powder, water and sulfuric acid are added to this, and the mixture is kneaded to form a paste. In the process of creating the lead powder, the average particle diameter of the red lead added to the lead powder having an average particle diameter of 4 μm to 7 μm is smaller than the average particle diameter of the lead powder. More preferably, the total amount of red lead particles added to the average particle size of the lead powder is smaller than the average particle size of the lead powder by 50 times or more.

Effect: By the above-mentioned means, the efficiency of chemical charging is improved when red lead is added to lead powder, but on the other hand, it is an attempt to improve the problem that the life characteristics are deteriorated.

In other words, when kneading the paste, with the total amount of lead oxide, water and sulfuric acid kept constant, the apparent density of the paste kneaded with lead powder alone and the apparent density of the paste kneaded with lead powder added and red lead powder are the same. When comparing the apparent densities of the pastes, theoretically the paste made by adding red lead to the lead powder has a lower density. For this reason, although the initial utilization rate after chemical charging is improved, the active materials soften and fall off early due to a decrease in the bonding force between the active materials, resulting in a decrease in life characteristics.

Therefore, the present invention aims to increase the apparent density of the paste after kneading by making the average particle diameter of red lead added to lead powder smaller than the average particle diameter of commonly used lead powder, 4 μm to 7 μm. This not only increases the bonding strength between the active materials, but also prevents them from softening and falling off at an early stage, thereby improving the life characteristics. More preferably, by making 50% by weight or more of the total amount of red lead particles smaller than the average particle size of the lead powder, the effect can be further increased and a greater improvement can be achieved.

Examples Examples of the present invention will be described below. First, from lower oxides of lead, the average particle diameter is 3 μm, 4 μm, 5 μm, 6 μm,
Different pieces of red lead of 7 μm were fired and added to lead powder having an average particle size of 5 μm as a representative example, with the amount of red lead kept constant at 40% by weight. Next, these and the lead powder alone were kneaded with water and sulfuric acid according to a conventional method to form a paste, which was applied to a grid and after aging and drying, a positive electrode plate was obtained. Batteries with a 5-hour rate capacity of 28 Ah were created using these batteries, and batteries with red lead added were subjected to chemical conversion at 110% of the theoretical chemical conversion electricity, and those containing only lead powder were chemically converted at 200% of the theoretical chemical conversion electricity. .

Thereafter, as a charge/discharge cycle test, discharging was performed at a 5 hour rate current until the terminal voltage of the battery reached 10.5V.
FIG. 1 shows the results of a cycle test in which charging was performed at 130% of the discharge capacity, and the number of cycles at which the discharge capacity decreased to 50% of the 5-hour rate capacity was determined. In the figure, A is lead powder only, B is lead powder with an average particle size of 3 μm added, and C is
is added with red lead with an average particle size of 4 μm, D is added with red lead with an average particle size of 5 μm, and E is added with red lead with an average particle size of 6 μm.
m and F indicate those to which red lead with an average particle size of 7 μm was added, respectively.

As is clear from the figure, red lead with an average particle size that is the same as or larger than the lead powder particle size is added, and E and F show high capacity at the beginning of the cycle, but the cycle is repeated. Accordingly, the capacity decrease becomes larger and the number of cycles is shorter than in A. However, for B and C to which red lead having an average particle diameter smaller than the average particle diameter of lead powder was added, the number of cycles was equal to or greater than that of A, and a remarkable effect can be seen.

Next, the results obtained in Fig. 1 were analyzed in more detail, and in the case where the average particle size of the red lead added was 4 μm, the first test was performed using a skewer containing a particle amount of red lead smaller than the average particle size of the lead powder. Figure 2 shows the results of a cycle test similar to that shown in the figure. From this, even if the average particle size of the red lead used is smaller than the average particle size of the lead powder, the degree of influence will differ depending on the content of particles smaller than the average particle type of the lead powder in the total amount of red lead particles. It can be seen that a greater effect can be obtained when 50% or more of the total particle amount of red lead is smaller than the average particle diameter of lead powder.

This effect is more pronounced when the amount of red lead added is in the range of 10% by weight or more and 40% by weight or less.

Effects of the Invention As described above, according to the present invention, the efficiency of chemical conversion charging when red lead is added is improved; This problem can be solved by selecting a combination of the average particle size and the average particle size of the lead powder, and its industrial value is extremely large.

[Brief explanation of drawings]

Figure 1 shows the results of a charge/discharge cycle test based on the average particle type of red lead added to lead powder, and Figure 2 shows the results of a charge/discharge cycle test based on the average particle size of red lead added to lead powder, and Figure 2 shows the results of a charge/discharge cycle test based on the average particle size of red lead added to the lead powder. FIG. 3 is a diagram showing the relationship between the content of particles smaller than the average particle diameter of lead powder and a charge/discharge cycle test. A: Only lead powder, with red added, with red added, with red added, with red added, with red added.

Claims (2)

[Claims] (1) In the process of adding red lead to lead powder and kneading it with water and sulfuric acid to create a paste, the average amount of red lead added to lead powder with an average particle size of 4 μm to 7 μm A method for producing a paste for a lead-acid battery, characterized in that a paste having a particle diameter smaller than the average particle diameter of the lead powder is used. (2) Claim 1, characterized in that 50% by weight or more of the total amount of red lead particles is smaller than the average particle diameter of lead powder.
A method for producing a paste for lead-acid batteries as described in Section 1.