JP6825270B2 - Manufacturing method of positive electrode plate for lead-acid battery - Google Patents

Description

The present invention relates to a method for manufacturing a positive electrode plate for a lead storage battery.

Generally, a positive electrode plate for a lead storage battery is manufactured as follows. First, a paste-like active material is prepared by kneading lead powder containing lead oxide as a main component, dilute sulfuric acid, water, and various additives such as cut fiber, and then a collection of lead or a lead alloy. The electric body is filled with the paste-like active material to prepare an undried electrode plate. Next, a large number of undried plates are suspended and loaded on a frame and placed in a high-temperature and high-humidity atmosphere for a predetermined time (for example, 20 hours or more) for aging (aging step). After that, a drying process is performed to manufacture a positive electrode plate for an unchemical lead-acid battery.

In the aging step, metallic lead in the paste-like active material is oxidized by mediating water to generate lead oxide, lead hydroxide, lead carbonate, etc., and tribasic lead sulfate and tetrabasic lead sulfate. To increase the binding force between active material particles. Then, the metallic lead on the surface of the current collector is oxidized to lead oxide, lead hydroxide, lead carbonate, etc., and the product is combined with the product in the active material to be between the current collector and the active material. Also enhances the adhesion of. At this time, if the crystal growth of the tetrabasic lead sulfate is promoted, the shrinkage of the active material due to drying can be reduced, so that the adhesion between the current collector and the active material can be further enhanced. Therefore, as the aging progresses, the amount of metallic lead in the active material decreases, and at the end of the aging process, it is generally about 6% by mass or less.

On the other hand, by aging, the water content in the positive electrode active material also decreases, and at the end of the aging step, it is generally 4% by mass or less. However, a sharp decrease in the water content in the positive electrode active material in the aging step may cause peeling or cracking of the positive electrode plate after aging and drying. To solve such a problem, for example, Patent Document 1 discloses a technique for increasing the water content in the positive electrode active material by adding water to the electrode plate during the aging process.

Japanese Unexamined Patent Publication No. 9-097604

However, in the technique described in Patent Document 1, since water is added intermittently, the water content in the active material repeatedly rises and falls, and the reaction in the current collector and the active material during aging varies. May occur. In this case, the life of the lead storage battery using the obtained positive electrode plate may be shortened.

Therefore, an object of the present invention is to provide a method for manufacturing a positive electrode plate for a lead storage battery, which can improve the life of the lead storage battery.

The present invention is a method for manufacturing a positive electrode plate for a lead storage battery, which comprises an aging step of aging a current collector filled with a positive electrode active material, wherein the water content in the positive electrode active material at the start of the aging process is 8 mass. % Or more, and in the aging step, a method for producing a positive electrode plate for a lead storage battery, which maintains the water content in the positive electrode active material at 7% by mass or more for 12 hours or more.

In this production method, the water content in the positive electrode active material at the start of the aging step is 8% by mass or more, and in the aging step, the water content in the positive electrode active material is 7% by mass or more. By maintaining for a predetermined time from the above, the reaction in the current collector and the active material can be homogenized, and the rapid metallic lead generated when the water content in the positive electrode active material is in the vicinity of 6 to 7% by mass. The oxidation reaction can occur later in the aging process. Therefore, the metallic lead of the active material and the current collector can be sufficiently converted into lead oxide, lead hydroxide, lead carbonate, etc., and the crystal growth of tetrabasic lead sulfate can be promoted. Therefore, a positive electrode plate capable of strengthening the bond between the active materials and between the current collector and the active material and, as a result, improving the life of the lead storage battery can be obtained.

This manufacturing method further includes a step of storing the current collector filled with the positive electrode active material in a state of being covered with a water evaporation suppressing means for suppressing the evaporation of water from the positive electrode active material before the aging process. You may.

In this production method, in the aging step, the current collector filled with the positive electrode active material may be aged in a state of being covered with a water evaporation suppressing means for suppressing the evaporation of water from the positive electrode active material.

According to the present invention, it is possible to provide a method for manufacturing a positive electrode plate for a lead storage battery, which can improve the life of the lead storage battery.

Hereinafter, embodiments of the present invention will be described in detail.

In one embodiment, a method for manufacturing a positive electrode plate for a lead storage battery (hereinafter, also simply referred to as a “positive electrode plate”) includes a current collector manufacturing step for manufacturing a current collector and a positive electrode active material manufacturing step for manufacturing a positive electrode active material. , A filling step of filling the current collector with the positive electrode active material, a aging step of aging the current collector (also called an undried positive electrode plate) filled with the positive electrode active material, and drying the undried positive electrode plate after aging. It has a drying process.

In the current collector manufacturing step, for example, a grid-shaped current collector is manufactured. The current collector can be obtained by molding lead or a lead alloy by a book mold (gravity casting) method, a continuous casting method, an expanding method, a punching method, or the like.

In the positive electrode active material manufacturing step, for example, lead powder, lead tan, dilute sulfuric acid, water and additives are mixed to obtain a paste-like positive electrode active material. The additive is added for the purpose of increasing the strength of the active material, and may be PET (polyethylene terephthalate), acrylic fiber, or the like.

In the filling step, for example, the paste-like positive electrode active material obtained as described above is filled between the lattices of the grid-like current collector made of lead or a lead alloy obtained as described above. As a result, a current collector (undried positive electrode plate) filled with the positive electrode active material can be obtained.

In the aging step, the undried positive electrode plate is aged. The temperature in the aging step may be, for example, 60 to 90 ° C, 60 to 70 ° C, 70 to 80 ° C, or 80 to 90 ° C. The relative humidity in the aging step may be, for example, 70-100%, 70-80%, 80-90%, or 90-100%. The aging time in the aging step may be, for example, 20 to 50 hours, 20 to 30 hours, 30 to 40 hours, or 40 to 50 hours.

The aging step may include a first step of aging under the above conditions and a second step of aging under conditions different from the first step.

In the aging step, the water content in the positive electrode active material at the start of aging is set to 8% by mass or more. The water content in the positive electrode active material at the start of aging is preferably 9.0% by mass or more, more preferably 9.3% by mass or more, still more preferably 9.4, from the viewpoint of further improving the life of the lead storage battery. It is mass% or more. The water content in the positive electrode active material at the start of aging may be, for example, 15% by mass or less. The water content in the positive electrode active material is measured using, for example, an infrared moisture meter (for example, product name FD-720 manufactured by Kett Chemical Laboratory Co., Ltd.).

In the aging step, the water content in the positive electrode active material is maintained at 7% by mass or more for 12 hours or more from the start of aging. The time for maintaining the water content in the positive electrode active material at 7% by mass or more is preferably 13 hours or more, more preferably 14 hours or more, still more preferably 15 hours or more, from the viewpoint of further improving the life of the lead storage battery. Especially preferably, it is 16 hours or more. The time for maintaining the water content in the positive electrode active material at 7% by mass or more may be, for example, 30 hours or less.

In all or part of the aging step, the undried positive electrode plate may be aged in a state of being covered with a moisture evaporation suppressing means. In this case, it becomes easy to maintain the water content in the positive electrode active material at 7% by mass or more. The water evaporation suppressing means is not particularly limited as long as it can suppress the evaporation of water from the positive electrode active material. The water evaporation suppressing means may be, for example, a sheet or cloth formed of a water-repellent material such as polyester, nylon, or a fluorine-containing compound. These sheets and cloths may be formed in a bag shape capable of accommodating, for example, an undried positive electrode plate.

In the drying step following the aging step, the undried positive electrode plate after aging is dried. Drying is carried out, for example, in an environment at a temperature of 55 to 65 ° C. for 92 to 192 hours. As a result, a (unconverted) positive electrode plate is obtained.

In one aspect, the method for manufacturing a positive electrode plate is a storage in which a current collector (undried positive electrode plate) filled with a positive electrode active material is stored in a state of being covered with a moisture evaporation suppressing means between a filling step and an aging step. Further steps may be provided. The water evaporation suppressing means used in the storage step is the same as described above. The water evaporation suppressing means used in the storage step and the water evaporation suppressing means used in the aging step may be the same or different from each other.

The temperature in the storage step may be, for example, 0 to 45 ° C, 0 to 15 ° C, 15 to 30 ° C, or 30 to 45 ° C. The relative humidity in the storage step may be, for example, 10-100%, 10-40%, 40-70%, or 70-100%. The storage time in the storage step may be, for example, more than 0 hours and 6 hours or less, more than 0 hours and 2 hours or less, 2 to 4 hours, or 4 to 6 hours.

The positive electrode plate obtained as described above is used as a positive electrode plate for a lead storage battery. The lead-acid battery includes, for example, a plurality of the positive electrode plates, a plurality of negative electrode plates, a plurality of separators, a hollow electric tank, and a lid for sealing the electric tank. The positive electrode plate and the negative electrode plate are arranged alternately, and a separator is provided between each positive electrode plate and the negative electrode plate. A group of electrode plates composed of a positive electrode plate, a negative electrode plate, and a separator laminated in this way is housed in an electric tank. The lid is provided with, for example, a control valve for controlling the pressure in the battery case, a positive electrode terminal for connecting the positive electrode plate to the outside, and a negative electrode terminal for connecting the negative electrode plate to the outside.

In this lead-acid battery, since the above-mentioned positive electrode plate in which the active materials and the current collector and the active material are firmly bonded is used, an excellent life (particularly, a cycle life) can be obtained. Examples of the use of the lead-acid battery of the present embodiment include main power supply use (Cycle Use), backup power supply use (Trickle Use), and the like, and in particular, main power supply use (cycle use (cycle use)). Cycle Use)) is preferable.

Hereinafter, the present invention will be described in more detail based on Examples, but the present invention is not limited to the following Examples.

Common to Examples 1 and 2 and Comparative Examples 1 and 2, cut fibers are added to a paste mixed at a ratio of 10 parts by mass of lead powder, 1 part by mass of dilute sulfuric acid (specific gravity 1.260), and 1 part by mass of water. A paste-like positive electrode active material was obtained by adding and kneading. The amount of paste-like positive electrode active material per positive electrode plate is 258 g in a current collector of a single plate (height 144 mm, width 145. mm, thickness 3.75 mm) cast using a lead-calcium alloy. Was filled with a paste-like positive electrode active material.

Then, in Example 1, during the storage step before the aging step and during the aging step, the current collector filled with the paste-like positive electrode active material was covered with a water-repellent cloth made of polyester to protect it from the wind. The conditions of the storage process and the aging process are as follows.
Storage process: Temperature 25 ° C., relative humidity 60% for 1 hour Aging process: Temperature 80 ° C., relative humidity 98%, and temperature 65 ° C., relative humidity 70% for 21 hours or more each, lead-acid battery A positive electrode plate for use was manufactured.

In Example 2, the same as in Example 1 except that the current collector filled with the paste-like positive electrode active material was covered with a water-repellent cloth made of polyester to protect it from the wind only during the storage step before the aging step. A positive electrode plate for a lead storage battery was manufactured.

In Comparative Example 1, a positive electrode plate for a lead storage battery was manufactured in the same manner as in Example 1 except that the current collector filled with the paste-like positive electrode active material was windshielded with a windshield tent only during the storage process before the aging process.

In Comparative Example 2, a positive electrode plate for a lead storage battery was manufactured in the same manner as in Example 1 except that the windshield was not provided in either the storage step or the aging step.

The water content W in the positive electrode active material at the start of aging in each Example and Comparative Example was measured at 130 ° C. for 10 minutes using an infrared moisture meter (manufactured by Kett Chemical Laboratory Co., Ltd., product name FD-720). Then, it was calculated from the following formula.
W (mass%) = (M1-M2) / M1 × 100
In the formula, M1 represents the mass of the positive electrode active material before the measurement (at the start of the aging process), and M2 represents the mass of the positive electrode active material after the measurement (after 10 minutes have passed at 130 ° C.).

Further, during the aging process, the positive electrode active material was sampled every hour, and the water content in the positive electrode active material was measured by the same method as described above. Table 1 shows the water content in the positive electrode active material at the start of the aging step and the time until the water content in the positive electrode active material becomes less than 7% by mass in the aging step.

Further, XRD measurement was performed on the obtained positive electrode plate (unmodified positive electrode plate), and the XRD peak intensity ratio (3BS / 4BS) of tribasic dilute lead sulfate and tetrabasic dilute lead sulfate was calculated. The results are shown in Table 1.

On the other hand, a lead storage battery was produced according to the following procedure.
First, dilute barium sulfate, vanillex N, acetylene black, and cut fiber are added to a paste mixed at a ratio of 10 parts by mass of lead powder, 1 part by mass of dilute sulfuric acid (specific gravity 1.260), and 0.47 parts by mass of water. And kneaded to obtain a paste-like negative electrode active material. Next, the amount of the paste-like negative electrode active material per negative electrode plate was 175 g in the current collector of a single plate (height 146 mm, width 147 mm, thickness 2.2 mm) cast using a lead-calcium alloy. A negative electrode plate for a lead storage battery was manufactured by filling with a paste-like negative electrode active material.
A group of electrode plates was prepared using 8 positive electrode plates, 9 negative electrode plates, and a retainer of each of the above-mentioned Examples and Comparative Examples, and 6 electrode plates were connected in series. After that, 0.2CA charging and 0.2CA discharging were repeated three times at a set temperature of 40 ° C. in the water tank, and then 0.12CA charging was performed to carry out battery chemical conversion over a total of 67 hours, and a 12V type sealed lead was used. A storage battery was manufactured.

A cycle test was carried out on the obtained lead-acid battery. The cycle test condition is that 2CA discharge and pause are repeated 5 times, and then the charge current value is stepped in the order of 0.15CA, 0.10CA, 0.05CA, 0.04CA to obtain a volume ratio of 115 to 120% of the discharge amount. The pattern was set so that the battery would be charged. When the storage battery voltage at the time of discharge became 8.75 V or less, the cycle life was determined. The results of the cycle test are shown in Table 1.

From Table 1, the water content of the positive electrode active material at the start of the aging process is 8% by mass or more, and the water content in the positive electrode active material is maintained at 7% by mass or more for 12 hours or more during the aging process. As a result, it was confirmed that the XRD peak intensity ratio (3BS / 4BS) of the tribasal dilute lead sulfate and the tetrabasic dilute lead sulfate of the denified positive electrode plate was reduced. It can be said that the smaller the XRD peak intensity ratio, the more the crystal growth of tetrabasic dilute lead sulfate is promoted, and the positive electrode active material and the current collector are firmly bonded. In this case, it was found that a lead-acid battery having an excellent cycle life characteristic and a long life can be obtained.

Claims (2)

A method for manufacturing a positive electrode plate for a lead storage battery, which comprises a aging step of aging a current collector filled with a positive electrode active material.
Prior to the aging step, a step of storing the current collector filled with the positive electrode active material in a state of being covered with a water evaporation suppressing means for suppressing the evaporation of water from the positive electrode active material is further provided .
In the aging step, the water content in the positive electrode active material at the start of aging is 8% by mass or more, and the water content in the positive electrode active material is 7% by mass or more for 12 hours or more from the start of aging. A method of manufacturing a positive electrode plate for a lead-acid battery to be maintained . A method for manufacturing a positive electrode plate for a lead storage battery, which comprises a aging step of aging a current collector filled with a positive electrode active material.
In the aging step, the current collector filled with the positive electrode active material is aged in a state of being covered with a water evaporation suppressing means for suppressing the evaporation of water from the positive electrode active material, and the positive electrode activity at the start of aging is performed. A method for producing a positive electrode plate for a lead storage battery , wherein the water content in the substance is 8% by mass or more, and the water content in the positive electrode active material is maintained at 7% by mass or more for 12 hours or more from the start of aging .