JP2000357532A - Manufacturing method of lead storage battery - Google Patents

Abstract

(57) [Problem] To provide a lead storage battery having excellent high-rate discharge characteristics and cycle life characteristics while using a thin electrode plate. SOLUTION: Using a water-soluble silicone as a binder, a positive / negative thin electrode plate in which an active material is coated on a core material is formed into a group of electrodes via a separator, and heat treatment is performed in this state to perform aging. This is a manufacturing method that is a process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a lead storage battery,
In particular, the present invention relates to a method for manufacturing a sealed lead-acid battery having excellent cycle life characteristics and high-rate discharge characteristics.

[0002]

2. Description of the Related Art At present, paste type electrode plates are most widely used in lead-acid batteries as an industrial production method with high productivity. The paste type electrode plate is a paste obtained by adding water and dilute sulfuric acid to a mixed powder of lead and lead oxide (hereinafter referred to as “lead powder”) in the voids of a current collector made of a cast or expanded lattice made of lead or a lead alloy. After filling, aged and dried to produce an unformed electrode plate. In this paste filling step, if necessary, the electrode plate immediately after filling is immersed in dilute sulfuric acid to generate lead sulfate on the surface of the electrode plate, thereby strengthening the electrode plate, followed by aging to complete the electrode plate. The unformed electrode plate thus formed is converted into a single electrode plate or a state assembled in a battery and then formed in a dilute sulfuric acid electrolytic solution to convert the positive electrode and the negative electrode into lead dioxide and spongy lead, respectively. The electrode plate or battery is completed.

[0003] The main component of the lead powder for a lead storage battery is lead monoxide, and it also contains 15 to 35% of metallic lead. A paste obtained by kneading lead powder with dilute sulfuric acid becomes basic lead sulfate due to lead monoxide in which excess lead sulfate is present, and maintains an appropriate hardness and shear elasticity. During the aging and drying, the intra-lattice paste is hardened by the oxidation of metallic lead and the crystal growth of basic lead sulfate, which partially evaporates moisture and causes a cementation phenomenon in which powder particles are bound to each other. This paste-type electrode plate is excellent in productivity and cost performance, and can be said to be an extremely effective industrial electrode plate manufacturing method.

In recent years, for various electric tools, for starting an engine,
As a high power source for electric vehicles, etc., a cylindrical hermetic seal consisting of a group of electrode plates in which a thin positive / negative electrode plate in which active material is thinly and uniformly applied to both sides of a non-perforated lead sheet is spirally wound through a separator Lead-acid batteries have been proposed in U.S. Pat. Nos. 5,050,586, 5,047,300 and 5,198,313. Such a thin electrode plate aims to improve characteristics in high-rate discharge by increasing the current collecting area and shortening the diffusion distance of sulfuric acid.

[0005]

In the case of such a thin electrode plate, the paste described above cannot be applied thinly and uniformly because of its high viscosity. Therefore, a method has been adopted in which a low-viscosity slurry kneaded only with water is thinly applied to both surfaces of a lead sheet without using sulfuric acid at all as a powder material containing lead powder as a main component. The positive and negative electrode plates produced as described above are spirally grouped together with the separator, inserted into a battery case, and subjected to battery formation in dilute sulfuric acid as it is.
The aging step as described above is an important step that affects the discharge characteristics of the battery.However, since the thin electrode plate as described above uses a slurry that does not contain sulfuric acid, it is similar to an electrode plate using a conventional paste. Aging treatment cannot be performed. Therefore, at present, the discharge capacity is reduced and the cycle is deteriorated.

In order to solve such a problem, a thin electrode plate is immersed in dilute sulfuric acid, sulfuric acid is contained in the active material layer, and then the lead powder is reacted with sulfuric acid while controlling the temperature and humidity. Aging process is conceivable. However, in this method, the active material layer falls off from the core material due to the volume expansion of the particles due to the reaction between lead powder and sulfuric acid. Further, although the above-described lead powder cementation reaction occurs, it is impossible to form the cured electrode plates in a spiral group because the active material layer is cracked or falls off.

[0007] In order to prevent such active material layer from cracking or falling off, N containing polyvinylidene fluoride as a binder is added.
A technique for preparing an active material slurry by using -methylpyrrolidone as a kneading liquid has been proposed in JP-A-10-261432. However, in this method, since an organic solvent is used in the electrode plate manufacturing process, the process is complicated.

The present invention suppresses the fall of the active material from the core material without using the above-mentioned organic solvent as a kneading liquid of the active material slurry, and achieves both improvement of the high rate discharge characteristics and improvement of the cycle life characteristics. The object is to provide a high-performance lead-acid battery.

[0009]

In order to achieve the above-mentioned object, a first aspect of the present invention is to provide a powdery material containing a mixture of lead and lead oxide or lead-tin as a water-soluble silicon-based polymer. A paste kneaded with water and water is applied to a core material made of a conductive sheet to form a positive electrode plate, and the electrode plate group including the positive electrode plate and the negative electrode plate and the separator is immersed in dilute sulfuric acid. The heat treatment is performed on the group.

According to a second aspect of the present invention, the heat treatment is performed at 40 ° C.
This indicates that the process is performed at ~ 80 ° C. According to a third aspect of the present invention, the electrode plate group spirally winds the positive electrode plate and the negative electrode plate via a separator.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a manufacturing flow of a sealed lead-acid battery according to the present invention. A low-viscosity paste obtained by adding a water-soluble silicon-based polymer (hereinafter referred to as silicone) as a binder and water as a solvent to an active material source powder mainly containing lead powder and kneading the resulting mixture into a sheet-like current collector. After applying thinly and uniformly, remove the solvent to make the electrode plate. Next, the produced positive electrode plate and negative electrode plate are wound via a separator to form an electrode plate group. This is immersed in dilute sulfuric acid having a specific gravity of 1.20 to 1.40,
After impregnating the separator and the active material layer with sulfuric acid,
An aging step of drying in an 80 ° C. constant temperature bath for 1 to 4 hours is performed.

According to the above-mentioned production method, peeling between the current collector and the active material due to the reaction between the active material and sulfuric acid is suppressed by the pressure applied to the electrode plate group by the winding and the silicone, and good aging is achieved. Thus, a sealed lead-acid battery having excellent cycle life characteristics and high-rate discharge characteristics can be obtained.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The following embodiments of the present invention will be described with reference to the drawings. First, the preparation of the electrode plate was performed. In this example, the raw material of the positive electrode plate or the negative electrode plate was 25% by weight,
Using lead powder consisting of 75% of lead monoxide (degree of oxidation 75%)
For the negative electrode, a mixed material was prepared using, as additives, 2% barium sulfate, 1% carbon powder, and 0.5% lignin based on the lead powder. Incidentally, as an additive for the positive electrode, in addition to the above, it is possible to add a lead compound such as red lead, basic lead sulfate or lead dioxide.

A solution in which the binder silicone is made 50% with water as a solvent is added to the above raw material powder so that the silicone becomes 3% of the raw material powder, and the mixture is uniformly kneaded to form a paste. However, the concentration of the binder can be changed appropriately according to the required viscosity of the paste.

Next, the obtained paste was applied to both surfaces of a sheet-shaped core material made of a lead-tin alloy and having a thickness of about 50 μm by a doctor blade method. The coating amount at this time was based on a coating amount of 30 mAh of theoretical capacity on both sides per 1 cm ² of the core material for the positive electrode and 40 mAh for the negative electrode. These electrodes are left in a dryer adjusted to a temperature of 80 ° C. for 2 hours to remove water. The dissolved silicone is precipitated and hardened and binds between the active material raw particles and between the current collector and the raw material particles.

FIG. 2A is a sectional view of these electrode plates, and FIG. 2B is a front view thereof. The paste 1 is not applied to the entire surface of the conductive core material 2, but partially exposes the core material 2 as shown in FIG. FIG. 3 shows an axial cross section of the electrode plate group in a state where the exposed portions of the positive electrode plate and the negative electrode plate are wound in directions opposite to each other with respect to the axial direction.

Each of the positive electrode 3 and the negative electrode plate 4 has a thickness of 0.7 m.
The glass plate is wound spirally around a winding core 6 via a glass mat separator 5 of m to form a cylindrical electrode group. In this way, the portions where the paste of the positive and negative electrode cores are not applied are respectively directed in opposite directions to be exposed from the separator. This was based on the method described in Japanese Patent Publication No. 5-503604. The winding pressure applied to the electrode plate group at this time is 50 k.
g / dm ² . The used positive electrode sheet has a width of 50.
mm, length 170 mm, theoretical capacity 2.6 Ah, negative electrode sheet width 50 mm, length 220 mm, theoretical capacity 4.4 Ah
Thus, the positive electrode capacity-limited battery has a nominal capacity of 1.2 Ah.

A sulfuric acid solution having a specific gravity of 1.40 is placed in a sealable container, the entire power generation unit is immersed in a sulfuric acid aqueous solution, the liquid is sufficiently contained by vacuum impregnation, and the pressure is returned to normal pressure.
Impregnated for minutes. This was taken out and ripened by a ripening step in which it was left for 2 hours in a dryer adjusted to a temperature of 40 ° C.
The active material mixture was firmly bound by the granulation effect of aging, in addition to being physically settled by the silicone.

Next, as for the mounting of the current collector, a current collector made of lead is mounted on the exposed core material portions of the positive and negative electrodes by spot welding. As shown in FIG. 4, the current collecting plate 7 does not completely cover both ends of the power generation unit, but has a gap 8 and an external output terminal 9 for injecting an electrolyte later. The aged power generation unit is inserted into an acrylic cylindrical outer case, and both ends of the cylindrical outer case are also covered with a disk made of acrylic and having a through hole in the center. The external output terminals of the positive electrode and the negative electrode are taken out of the case through the through holes. A hole for attaching a safety valve is provided in either the positive or negative lid. The gap between both output terminals and the through hole of the lid is filled with epoxy resin.

Next, dilute sulfuric acid (specific gravity: 1.15) was injected through a hole provided for a safety valve, and a battery container was formed at a constant current of 0.4 C for 7 hours. Replace with 1.30 diluted sulfuric acid, attach a safety valve and seal tightly.
A cylindrical lead-acid battery having a height of 55 mm and a height of 55 mm was prepared.

For comparison, a battery manufactured as a prototype in exactly the same steps as the present example except that the aging step was not performed was used as Comparative Example 1. A battery prepared in the same process as in this example using a slurry in which the same active material raw material powder as in this example was kneaded with only water without using a binder was used as Comparative Example 2. Further, a battery prepared in the same manner as in this example except that this aging step was not performed using the same slurry as in Comparative Example 2 was used as Comparative Example 3.

FIG. 5 shows the results of discharging these batteries at a discharge rate of 2C, and FIG. 6 shows the results of discharging them at 5C. As is clear from the figure, the discharge characteristics of the present example are significantly improved as compared with Comparative Examples 1, 2 and 3. The reason is considered as follows.

Compared to Comparative Example 1, the aging step is performed in this example, and the active materials are strongly connected to each other by cementation to form a conductive network.
In particular, it seems that the characteristics at high rate discharge are excellent. Next, in Comparative Example 2, since no binder was used, stress was applied due to expansion of the active material when lead powder changed to basic lead sulfate or lead sulfate in the aging step, and the binding property with the core material was increased. It is thought that the active material was poor in binding property and no conductivity because no binder was used. Furthermore, in Comparative Example 3, since there is no binder, the binding property with the core material and the binding property between the active materials are poor, and the formation of the conductive network is considered to be inferior to that of the present example. It is.

Further, in order to evaluate the cycle life, the batteries of this embodiment and Comparative Examples 1, 2, and 3 were each discharged at 1 C until the voltage reached 1.7 V, and the batteries were discharged at a constant current and a constant voltage (1 C, 2.
The cycle characteristics were examined under the condition of charging at 35 V) for 1.5 hours. The cycle life is that the discharge capacity is 50% of the initial capacity
The point when the temperature decreased to the end point was defined as the end point. Table 1 shows the results.

[0025]

[Table 1]

Table 1 clearly shows the superiority of this embodiment. It is considered that this is also due to the conductive network between the active materials and the binding property with the core material, as described above.
Among these, the reason why the result of Comparative Example 2 is particularly bad is considered to be that the active material and the core material were detached at the stage of the aging step before the completion of the battery because there was no binder.

On the other hand, under the aging conditions, the temperature is preferably in the range of 40 ° C. to 80 ° C. Below this temperature, the cementation effect of the active material is weakened even after aging for a long time, and the active material layer becomes rather brittle, and both the discharge characteristics and the cycle characteristics deteriorate as compared with the comparative example. Further, it has been found that when the temperature is higher than this temperature, the discharge capacity is significantly deteriorated. This is probably because a large amount of tetrabasic lead sulfate is generated at a high temperature, and αPb02, which is disadvantageous to the discharge reaction during chemical formation, increases.

In the present embodiment, a battery in which the electrode plates are wound in a cylindrical shape is mainly described. However, similar results are obtained for batteries in which the cross section of the power generation unit is configured in an elliptical or oval shape. Further, even in the case of a prismatic battery in which electrode plates are stacked, it is possible to manufacture a lead storage battery having similar characteristics by creating an electrode plate in the same manner as in the present embodiment and thereafter stacking the electrode plates. it can.

[0029]

As described in detail above, according to the present invention, it is possible to obtain a lead-acid battery having excellent high-rate discharge characteristics and cycle life.

[Brief description of the drawings]

FIG. 1 is a diagram showing a manufacturing flow of a lead storage battery according to an embodiment of the present invention.

FIG. 2 is a view showing a thin electrode plate according to an embodiment of the present invention;

FIG. 3 is a sectional view of an electrode group of a cylindrical lead-acid battery according to an embodiment of the present invention.

FIG. 4 is an exploded perspective view of an electrode group and an output terminal of a cylindrical lead-acid battery according to an embodiment of the present invention.

FIG. 5 is a diagram showing discharge characteristics of one example of the present invention and a comparative example.

FIG. 6 is a diagram showing discharge characteristics of one example of the present invention and a comparative example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Active material layer 2 Sheet-shaped current collector 3 Positive electrode 4 Negative electrode 5 Separator 6 Core 7 Current collector 8 Gap 9 External output terminal

Continued on the front page F-term (reference)

Claims (3)

[Claims] 1. A paste obtained by kneading a mixture of lead and lead oxide or a powder material containing lead as a main component, a water-soluble silicon-based polymer silicone, and water on a core material made of a conductive sheet. A method for producing a lead-acid battery, comprising: forming a positive electrode plate; immersing an electrode plate group including the positive electrode plate, the negative electrode plate, and a separator in dilute sulfuric acid; and heat-treating the electrode plate group. 2. The method according to claim 1, wherein the heat treatment is performed at 40 ° C. to 80 ° C. 3. The method for producing a lead-acid battery according to claim 1, wherein the electrode plate group is formed by spirally winding a positive electrode plate and a negative electrode plate via a separator.