JPH0837002A - Manufacture of positive electrode plate for lead-acid battery - Google Patents

Abstract

PURPOSE:To provide a positive electrode plate for lead-acid battery which can suppress the phenomenon that an active material at the boundary between an electricity collector and an active material layer is turned in passive state or that active material is turned muddy without causing drop of the battery discharge capacity. CONSTITUTION:An electricity collector consisting of lead or lead alloy is filled with an active material paste whereto sodium sulfate is added and which exhibits an alkalinity between pH10.5-11.5 so that an electrode plate not having undergone chemical formation. This electrode plate is immersed in an electrolytic solution of pH0.5-0.7 to which sodium sulfate is added, and thus chemical formation is conducted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a positive electrode plate for a lead storage battery.

[0002]

2. Description of the Related Art When making a positive electrode plate for use in a lead-acid battery such as a sealed lead-acid battery, first, a lead powder containing lead oxide as a main component and dilute sulfuric acid are first added to a current collector composed of a lead or lead alloy lattice. An undried electrode plate is prepared by filling an active material paste prepared by kneading and. Next, the undried electrode plate is aged and dried to form an unformed electrode plate, and the unformed electrode plate is formed in an electrolytic solution containing dilute sulfuric acid to form an active material layer containing β-PbO ₂ as a main component. To do. When charging and discharging are repeated in this type of lead storage battery, discharge is preferentially generated at the interface between the current collector of the positive electrode plate and the active material layer as compared with other portions of the active material. Therefore, the active material in the vicinity of this interface hardly becomes a charge product, and so-called passivation occurs. Especially non-antimony (Sb alloy such as Pb-Ca-Sn alloy)
When the current collector is formed by using the b) type alloy, the passivation of the active material becomes remarkable. Further, when charging and discharging are repeated, particles of the active material (β-PbO ₂ ) become finer, the binding force between the active material particles decreases, and the active material softens and falls off, causing a mud phenomenon. Therefore, there is a problem that the capacity of the battery decreases. Therefore, a compound that makes the liquid alkalinity is added to the electrolytic solution forming the unformed electrode plate to adjust the pH of the electrolytic solution, and α-poor reactivity is formed in the vicinity of the interface between the current collector and the active material layer. generates a PbO _2, also by generating active beta-PbO ₂ reaction to distant parts from the interface, it has been proposed to suppress the passivation and slurried (JP 4-723
No. 51). Since α-PbO ₂ is more inactive than β-PbO _2, it is less likely to cause a discharge reaction, and passivation and mudification of the interface between the current collector and the active material layer can be suppressed.

[0003]

However, even when the lead-acid battery is manufactured in this manner, the passivation of the active material and the mudification of the active material at the interface between the current collector and the active material layer are prevented. There was a limit to suppressing both. Further, in order to suppress this, it is conceivable to increase the amount of α-PbO ₂ in the active material, but if the amount of α-PbO ₂ becomes too large, the high rate discharge performance of the battery deteriorates.

An object of the present invention is to prevent the passivation of the active material and the mudification of the active material at the interface between the current collector and the active material layer without reducing the discharge capacity of the battery. It is to provide a method for manufacturing a positive electrode plate for a storage battery.

[0005]

According to the present invention, a current collector made of lead or a lead alloy is filled with an active material paste to form an unformed electrode plate, and a compound that makes the unformed electrode plate alkaline is liquid. A method for producing a positive electrode plate for a lead storage battery by immersing it in an electrolytic solution containing a compound to form a positive electrode plate, and a liquid having an alkaline property as an active material paste, pH 10.5 to 1
Using an active material paste of 1.5, the pH of the electrolytic solution was 0.
An electrolytic solution of 5 to 0.7 is used.

It is preferable to use a neutral salt of an alkali metal as the compound which makes the liquid alkaline. The use of a neutral salt of an alkali metal has an advantage that the safety is higher than that when a hydroxide such as NaOH is used. The neutral salt of alkali metal referred to here is sodium sulfate (Na ₂
It is a neutral salt containing an alkali metal (Na etc.) such as SO ₄ ).

As the active material paste, an active material paste having a pH of 10.5 to 11.5 obtained by adding a neutral salt of an alkali metal may be used.

It is preferable to use sodium sulfate as the neutral salt of the alkali metal. Since sodium sulfate is inexpensive, the positive electrode plate for lead acid battery can be manufactured at low cost.

[0009]

[Function] When an unformed electrode plate is prepared by using an active material paste having a pH of 10.5-11.5, the solubility of lead, lead monoxide, and lead hydroxide in the current collector and the active material in the paste solution is increased. Get higher As a result, the dissolved lead, lead monoxide, and lead hydroxide from the current collector increase the binding force at the interface between the current collector and the active material layer, and lead, monoxide, dissolved from the active material, Lead hydroxide increases the mutual binding force of the active material particles. In addition, when the active material paste having a pH of 10.5 to 11.5 is used as described above, the active material layer has a structure in which the electrolytic solution easily diffuses inside during formation. Therefore, even if the amount of α-PbO ₂ in the active material increases, it is possible to suppress deterioration of the high rate discharge characteristics of the battery. When the pH exceeds 11.5 and the alkalinity of the active material paste becomes high, the α-PbO ₂ layer at the interface between the current collector and the active material layer becomes too thick, and this α-PbO ₂ layer becomes After the formation of cracks, peeling easily occurs at the interface between the current collector and the active material layer.

Then, the unformed electrode plate was adjusted to pH 0.5 to 0.
When immersed in the electrolytic solution of No. 7 and formed to form α-PbO ₂ strongly bound to the current collector near the interface with the current collector, a skeleton of α-PbO ₂ is formed in the active material layer. . If the pH is lower than 0.5, the skeleton of α-PbO ₂ cannot be sufficiently formed. Further, when the pH of the electrolytic solution exceeds 0.7, the amount of α-PbO ₂ which is inactive in charge and discharge increases, and the discharge capacity of the battery decreases. Therefore, according to the present invention, a positive electrode plate capable of suppressing passivation of the active material and mudification of the active material at the interface between the current collector and the active material layer without reducing the discharge capacity of the lead storage battery. Obtainable.

[0011]

EXAMPLES Each positive electrode plate used in the tests including this example was manufactured as follows. First, of a mixture of 75.4% by weight of lead powder containing lead monoxide (PbO) as a main component, 10% by weight of water, and 12.4% by weight of dilute sulfuric acid having a specific gravity of 1.26 (20 ° C.). In addition, a predetermined amount (the amount shown in the column of the active material paste A in Table 1 below) of sodium sulfate (Na ₂ S
A neutral salt of O ₄ ) was added and further kneaded to prepare various active material pastes having different pHs. Then, 26 g of each of these active material pastes was filled in a current collector composed of a lattice of a non-antimony (Sb) -based alloy composed of a Pb-Ca-Sn alloy to prepare a undried electrode plate. Next, the undried electrode plate is left for 40 hours in an atmosphere having a temperature of 40 ° C. and a humidity of 98% to be matured, and then left in an atmosphere having a temperature of 50 ° C. for 16 hours to be dried to prepare an unformed electrode plate. .

Next, a predetermined amount (amount shown in the column of electrolyte B of Table 1) of neutral salt of sodium sulfate (Na ₂ SO ₄ ) is added to dilute sulfuric acid to add 1.05 of specific gravity having different pH. (2
Various electrolytic solutions of 0 ° C.) were prepared. Then, the unformed electrode plate is dipped in 14 ml of electrolyte solution for 1 g of the positive electrode active material,
At a temperature of 40 ° C., 250% of the theoretical amount of electricity was applied for 20 hours to conduct the formation. After the formation, each electrode plate was washed with water and dried to complete various positive electrode plates used in the test.

Next, two positive electrode plates were combined with three known paste type negative electrode plates and a separator mainly composed of glass fibers to prepare a sealed lead acid battery of 4Ah-2V. The electrolytic solution used was dilute sulfuric acid having a specific gravity of 1.32 (20 ° C.). A high rate discharge test and a cycle life test were performed using each battery. The high rate discharge test was conducted at a temperature of 25 ° C for each battery at 12
The discharge duration was measured by discharging with a current of A (3 CA) to a final voltage of 1.3 V. Table 1 shows the measurement results.

[0014]

[Table 1] From this table, Examples 1 to 6 and Comparative Examples 1, 2, 5, 7, 9,
It can be seen that the batteries using the positive electrode plates 11 to 13 have a discharge duration of 12 minutes or more and high high rate discharge performance.
The high rate discharge performance of the batteries using the positive electrode plates of Comparative Examples 3, 4, 6, 8, 10, and 14 is low because α-PbO ₂ is contained in the active material.
It was because there were many.

The cycle life test was conducted as follows using only the above-mentioned battery having high high rate discharge performance. After discharging each battery at a temperature of 25 ° C. with a current of 1 A (0.25 CA) to a final voltage of 1.7 V, a limiting current of 1.2 A
(0.25 CA), constant voltage constant voltage charging was performed for 8 hours at a set voltage of 2.45V. And the discharge capacity is 50 of the rated capacity.
The number of cycles of each battery up to the end of life was measured with the point at which the percentage was less than or equal to%. Table 1 shows the measurement results. From this table, the batteries using the positive electrode plates of Examples 1 to 6 have a cycle number of 300 times or more, and have high cycle life performance. These batteries have both high rate discharge performance and cycle life performance. You can see that it is expensive. When the batteries using the positive electrode plates of Comparative Examples 1, 2, 5, 7, 9, 11 to 13 having a short cycle life were disassembled, the passivation of the active material in the vicinity of the interface between the current collector and the active material layer was performed. It was observed that the active material became mud-like. This is because in the batteries using the positive electrode plates of Comparative Examples 1, 2, 5, 7, and 9 in which the pH of the active material paste was low, α in the active material after chemical conversion
This is because the amount of PbO ₂ was small. This is also because in the batteries using the positive electrode plates of Comparative Examples 11 to 13 in which the pH of the active material paste was high, the current collector and the active material layer were largely peeled off after chemical conversion. In this way, p of the active material paste
When H is high, the peeling between the current collector and the active material layer becomes large after chemical conversion. Further, it can be seen from this table that the capacity of the electrode plates of Comparative Examples 2 to 4 in which the amount of α-PbO ₂ is increased only by adjusting the pH of the chemical conversion liquid decreases.

In this embodiment, sodium sulfate (Na ₂ SO ₄ ) was used as the neutral salt, but other compounds such as K ₂ SO ₄ may be used.

The structure of some of the inventions described in the specification will be described below.

(1) A current collector made of lead or a lead alloy is filled with an active material paste to prepare an undried electrode plate, and the undried electrode plate is aged and dried to form an unformed electrode plate, In the method for producing a positive electrode plate for a lead storage battery, wherein the unformed electrode plate is formed in an electrolytic solution containing dilute sulfuric acid, an active material paste having a pH of 10.5 to 11.5 is used as the active material paste, and an alkaline solution is used as the electrolytic solution. A method for producing a positive electrode plate for a lead storage battery, which comprises adding a neutral salt of a metal to adjust the pH of the electrolytic solution to 0.5 to 0.7.

(2) A non-formed electrode plate is prepared by aging and drying a undried electrode plate in which a current collector made of lead or a lead alloy and sodium sulfate is added and an active material paste having a pH of 10.5 to 11.5 is filled. After the production, the unformed electrode plate is formed in an electrolytic solution having a pH of 0.5 to 0.7 containing sodium sulfate to produce a positive electrode plate for a lead acid battery, which is a positive electrode plate for a lead acid battery. Method.

(3) An active material paste prepared by kneading lead powder containing lead oxide as a main component, water, dilute sulfuric acid, and sodium sulfate is filled in a current collector made of a lead alloy containing no antimony. To make a undried electrode plate, and to ripen and dry the undried electrode plate to make an unformed electrode plate, and then to form the unformed electrode plate in an electrolyte solution containing dilute sulfuric acid to produce a positive electrode plate for a lead storage battery. In the method, the active material paste has a pH of 10.5 to
A positive electrode for a lead storage battery, characterized by using the active material paste of 11.5 to form the unformed electrode plate in an electrolytic solution having a pH of 0.5 to 0.7 by adding sodium sulfate to the diluted sulfuric acid. Method of manufacturing a plate.

[0021]

According to the present invention, since the active material paste having a pH of 10.5 to 11.5 is used as the active material paste and the electrolytic solution having a pH of 0.5 to 0.7 is used as the electrolytic solution, the discharge of the lead storage battery is performed. It is possible to obtain a positive electrode plate that can suppress passivation of the active material and mudification of the active material at the interface between the current collector and the active material layer without lowering the capacity.

Claims (4)

[Claims] 1. A current collector made of lead or a lead alloy is filled with an active material paste to form an unformed electrode plate, and the unformed electrode plate is immersed in an electrolyte solution containing a compound that makes the liquidity alkaline. In the method for producing a positive electrode plate for a lead storage battery by chemical conversion, the active material paste has a pH of which the liquidity is alkaline.
A method for manufacturing a positive electrode plate for a lead storage battery, which comprises using an active material paste of 10.5 to 11.5 and using an electrolytic solution of pH 0.5 to 0.7 as the electrolytic solution. 2. The method for producing a positive electrode plate for a lead storage battery according to claim 1, wherein a neutral salt of an alkali metal is used as the compound that makes the liquid property alkaline. 3. An unformed electrode plate is prepared by filling a current collector made of lead or a lead alloy with an active material paste, and the unformed electrode plate is prepared by adding a neutral salt of an alkali metal to dilute sulfuric acid to a pH of 0. 5-
A method for producing a positive electrode plate for a lead storage battery by immersing it in an electrolyte solution having a pH of 0.7 to perform formation, wherein a pH of 10.5 to 11.5 is obtained by adding a neutral salt of an alkali metal as the active material paste. A method for manufacturing a positive electrode plate for a lead storage battery, which comprises using an active material paste. 4. The method for producing a positive electrode plate for a lead storage battery according to claim 2, wherein the neutral salt of the alkali metal is sodium sulfate.