JPH05242882A - Lead-acid battery - Google Patents

Abstract

PURPOSE:To provide a lead-acid battery having structure capable of improving an overcharging characteristic. CONSTITUTION:A primary particle active material layer 3 consisting of primary particles 2 of an active material is formed in the periphery in contact with a current collector 1 of a positive electrode plate. A secondary particle active material layer 5 consisting of secondary particles 4 where the primary particles 2 of active materials are collected in high density is formed around the primary particle active material layer 3. Between the active materials constituting the primary particle active material layer 3 and the secondary particle active material layer 5, fine pores each having a diameter of 0.1mum or less exist in 0.03ml/g or more and fine pores each having a diameter of 0.5mum or more exist in 0.06ml/g or more as a whole.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a lead storage battery.

[0002]

2. Description of the Related Art Lead batteries are used as a backup power source for equipment in an emergency such as a power failure.
Normally, a lead storage battery is always in a charged state at a constant voltage, but a constant current may continue to flow due to a failure of a charger, and the lead storage battery is left in an overcharged state for a long time. If charge and discharge are repeated in a state where such overcharge occurs, the lead storage battery will reach the end of its life at an early stage. On the other hand, when the current value during charging with a constant voltage is large, the lead-acid battery has a shorter life than that when the current value is small, and the risk of heat runaway increases.

[0003]

The decrease in battery life due to repeated overcharging is mainly due to the positive electrode plate. In the positive electrode plate, the surface of the current collector gradually becomes PbO during overcharge.
Change to ₂ and volume expansion occurs. In addition, the active material is easily separated from the current collector due to the movement of oxygen gas generated in the positive electrode plate during overcharge. Then, sulfuric acid, which is an electrolytic solution, enters the current collector where the active material is peeled off, so that PbO ₂ is generated on the surface of the current collector at the time of discharge, and the discharge performance is deteriorated. Repeated overcharging thus shortens battery life.

On the other hand, the decrease in life during constant voltage charging is also caused by the positive electrode plate, so that the volume expansion of the current collector occurs in the same process as when overcharging, the active material peels off, and the battery capacity decreases.

In order to solve this problem, it is considered that many active material particles having small pores are present to suppress the diffusion of sulfuric acid toward the current collector side, but the diffusion of sulfuric acid is not good. The discharge capacity decreases.

An object of the present invention is to provide a lead storage battery having a structure capable of improving overcharge characteristics.

[0007]

The means of the present invention for achieving the above object will be described below.

According to a first aspect of the present invention, in a lead acid battery having a positive electrode plate using a lead alloy as a current collector, primary particles of an active material are formed in the periphery of the positive electrode plate in contact with the current collector.
A secondary particle active material layer is provided, and a secondary particle active material layer composed of secondary particles in which primary particles of the active material are densely aggregated is provided outside the primary particle active material layer. To do.

According to a second aspect of the invention, in the first aspect, between the active material particles constituting the primary particle active material layer and the secondary particle active material layer, a diameter of 0.1 μm or less is provided as a whole. It is characterized in that pores are present in an amount of 0.03 ml / g or more, and pores having a diameter of 0.5 μm or more are present in an amount of 0.06 ml / g or more.

[0010]

When the secondary particle active material layer is present on the surface of the electrode plate as described in claim 1, pores having a large diameter are formed on the surface of the electrode plate, and sulfuric acid as an electrolytic solution reaches the inside of the electrode plate. Diffusion is facilitated and discharge performance is improved. Since the specific surface area of the active material is reduced when the active material layer is formed by the secondary particles formed by aggregating the primary particles, the primary particles are charged with a constant current, rather than being present alone. Over voltage rises,
When charged at a constant voltage, the current value becomes small. And 2
When the secondary particles are present in the portion in contact with the current collector, the contact area between the current collector and the active material is reduced, the active material is easily separated from the current collector, and the large pore diameter facilitates the diffusion of sulfuric acid. Since the sulfuric acid is likely to come into contact with the current collector and the capacity is reduced, it is better to allow the secondary particles to exist on the electrode plate surface side.

Further, when a primary particle active material layer composed of primary particles of the active material is provided on the surface side of the current collector, the contact area between the current collector and the active material is increased, and the active material is removed from the current collector. Hard to peel off. Further, according to the primary particle active material layer, the pore diameter between the active material particles becomes small, the sulfuric acid becomes difficult to diffuse, and PbO ₂ becomes difficult to be generated on the surface of the current collector at the time of discharge, which results in a decrease in discharge performance. It can prevent the deterioration.

According to a second aspect, in the primary particle active material layer in contact with the current collector, 0.1 μ of the pores between the active material particles is used.
If the number of small pores of m or less is increased, the diffusion of gas generated during charging becomes worse, the gas is likely to accumulate in the electrode plate, and the reaction area decreases. The current value during voltage charging becomes smaller.

[0013]

EXAMPLES Examples of the present invention will be described in detail below in comparison with conventional examples and comparative examples.

The positive electrode plate was manufactured as follows.
First, PbO and Pb were added to the current collector made of Pb-Ca alloy.
A paste consisting of O ₄ is filled and then aged. Next, seven kinds of positive electrode plates were produced by changing the particle size of the active material and the chemical conversion conditions.

The types of the positive electrode plates produced are A, B, C, D,
E, F, and G, A and G are conventional products, B and C are products of the present invention,
D, E and F are comparative products.

A model diagram of these positive electrode plates is shown in FIG.
(B), FIG.2 (a) (b), and FIG.3 (a) (b) are shown.
1 (a), 2 (a) and 3 (a) show positive electrode plates B and C of the present invention, positive electrode plates A and G of conventional products, and positive electrode plates D, E and F of comparative products. 3 is a model diagram of the current collector 1 and its surroundings. In the positive electrode plate of the present invention shown in FIG. 1 (a), a primary particle active material layer 3 composed of primary particles 2 of the active material is provided in the periphery in contact with the current collector 1. Even in the conventional positive electrode plate shown in FIG. 2A, the active material
A primary particle active material layer 3 composed of secondary particles 2 is provided. However, the particle size of the primary particles 2 in this case is as shown in FIG.
In the case of, it is larger than the particle size of the primary particles 2. In the positive electrode plate F of the comparative product shown in FIG. 3A, the secondary particle active material layer 5 including the secondary particles 4 formed by the aggregation of the primary particles 2 is provided around the contact with the current collector 1. There is.

1 (b), 2 (b) and 3 (b),
The positive electrode plates B and C of the present invention, the positive electrode plates A and G of the conventional product,
It is a model view of the positive electrode plates D, E, and F of the comparative product on the surface side of the electrode plate. In the positive electrode plates B and C of the product of the present invention shown in FIG. 1B, the secondary particle activity consisting of the secondary particles 4 formed by stacking the primary particle active material layer 3 and gathering the primary particles 2 on the outer side. A material layer 5 is provided. In the conventional positive electrode plates A and G shown in FIG. 2 (b), the primary particle active material layer 3 composed of the primary particles 2 of the active material is again provided outside the primary particle active material layer 3. There is. ◎ Comparative positive electrode plate D shown in FIG.
In E and F, the secondary particle active material layer 5 composed of the secondary particles 4 formed by accumulating the primary particles 2 on the outer side of the secondary particle active material layer 5 is provided again. That is, in the conventional positive electrode plates A and G shown in FIG. 2B, the secondary particle active material layer 5 has an amorphous shape, while in the positive electrode plates A and G shown in FIGS. Two of positive electrode plates B, C of the invention product and positive electrode plates D, E, F of the comparative product
In the secondary particle active material layer 5, primary particles 2 smaller than the conventional product are formed of large secondary particles 4 densely aggregated. In this case, the average particle size of each active material of each positive electrode plate is as follows.

The average particle size of the active material primary particles in the conventional positive electrode plates A and G is 0.2 μm to 0.3 μm. The average particle size of the active material primary particles in the positive electrode plates B and C of the present invention is 0.1 μm to 0.1 μm. 0.2 μm The average particle diameter of the active material primary particles in the positive electrode plates D, E, and F of the comparative product is 0.1 μm to 0.2 μm, and the average particle diameter of the active material secondary particles in the positive electrode plates B and C of the present invention is 2 μm to The average particle diameter of the secondary particles of the active material in the positive electrode plates D, E, and F of the comparative product is 2.5 μm to 3.5 μm.

These positive electrode plates A, B, C, D, E, F, G
Comparing the magnitudes of the liquid gravities at the time of formation of C, C> (B,
D)> (A, E, F, G), and the magnitude of the energizing current is in the order of (D, G)>A> F. For B, C, E, the applied amount is the theoretical amount of electricity of the positive electrode plate. A current of the same magnitude as D and G was passed until it reached 60%, and then a current of the same magnitude as F. The amount of electricity applied at the end of formation is all 300%. The magnitude of the liquid temperature is in the order of F>D>A> G, and B,
Regarding C and E, the same temperature as A was maintained until the amount of applied electricity reached 60%, and then the temperature was gradually raised to the same temperature as F.

The positive electrode plates A, B, produced as described above,
Using C, D, E, F and G, a sealed lead acid battery of 30Ah-2V type was produced and provided for the test.

First, FIG. 4 shows the results of testing the sealed lead-acid batteries having the positive electrode plates of the conventional product A, the invention product B and the comparative product F by the overcharge cycle. The test conditions are at 25 ℃
Overcharged with a constant current of 0.1 CA, and once every 10 days 0.17
It was decided to confirm the capacity with a constant current of CA. as a result,
As shown in FIG. 4, the product B of the present invention has a longer life than the conventional product A, but the life of the comparative product F in which the secondary particles 4 are present around the current collector 1 is shorter.

Next, the current value during floating charging is shown in FIG.
As a test condition, a current value was measured when constant voltage charging was performed at 2.275 V / cell at 25 ° C. As a result, 0.5 μ
Since the pores with a diameter of m or more are 0.06 ml / g or more and the pores with a diameter of 0.1 μm or less are 0.03 ml / g or more, the current value is
It has decreased to 1/5.

Next, FIG. 6 shows the initial capacity when discharged at a constant current of 0.17 CA at 25 ° C., where the capacity of the conventional product A is 100%. Among the positive electrode plates B and G containing 0.06 ml / g or more having a pore size of 0.5 μm or more, the positive electrode plate B
1B, the secondary particles 4 are formed as shown in FIG. 1B, and the active material of the electrode plate G has an irregular shape as shown in FIG. Looking at FIG. 6, the discharge capacity becomes almost constant by including 0.05 ml / g or more of the pore size of 0.5 μm or more, but 0.06 ml / g of the pore size of 0.5 μm or more.
Even if it includes the above, the electrode plate G on which the secondary particles 4 are not formed
Have inferior discharge performance.

The method for producing the positive electrode plate of the present invention is not limited to that shown in this embodiment.

[0025]

As described above, according to the lead storage battery of the present invention, the following effects can be obtained.

In the invention described in claim 1, since the secondary particle active material layer is provided on the surface side of the positive electrode plate, pores having a large diameter are formed on the surface side of the positive electrode plate, and sulfuric acid as an electrolytic solution is added. It is easy to diffuse into the electrode plate, and the discharge performance can be improved. Further, when the active material layer is formed by the secondary particles formed by aggregating the primary particles, rather than the existence of the primary particles alone, the specific surface area of the active material decreases, so that the active material layer is charged with a constant current. When it does, the overvoltage increases, and when it is charged with a constant voltage, the current value decreases.

Further, since the primary particle active material layer made of the primary particles of the active material is provided on the surface side of the current collector, the contact area between the current collector and the active material is increased and the active material is collected. It becomes difficult to peel it off. Further, according to the primary particle active material layer, the pore diameter between the active material particles becomes small, sulfuric acid becomes difficult to diffuse, and PbO ₂ is hard to be generated on the surface of the current collector during discharge,
It is possible to prevent deterioration of discharge performance.

According to the second aspect of the invention, in the primary particle active material layer in contact with the current collector, the number of small pores of 0.1 μm or less among the pores between the active material particles is increased. Diffusion of the generated gas becomes worse, gas is likely to accumulate in the electrode plate, and the reaction area is reduced. If the battery is charged in this state, the overvoltage becomes high and the current value during constant voltage charging becomes small.

Therefore, according to the lead acid battery of the present invention,
To provide a battery that can improve the characteristics in overcharging and floating charging, reduce the risk of heat escape by reducing the current value during floating charging, and that does not impair the discharge capacity. You can

[Brief description of drawings]

1A is a model diagram showing the shape of an active material around a current collector of a positive electrode plate used in the present invention, and FIG. 1B is a model showing an active material shape on the surface side of a positive electrode plate used in the present invention. It is a figure.

FIG. 2A is a model diagram showing an active material shape around a current collector of a positive electrode plate used in a conventional product, and FIG. 2B is a model showing an active material shape on a surface side of a positive electrode plate used in a conventional product. It is a figure.

3A is a model diagram showing the shape of an active material around the current collector of the positive electrode plate used in the comparative product, and FIG. 3B is a model showing the active material shape on the surface side of the positive electrode plate used in the comparative product. It is a figure.

FIG. 4 is a diagram showing test results of overcharge cycles in lead-acid batteries of the present invention product, conventional product, and comparative product.

FIG. 5 is a diagram showing current values during floating charging in the lead-acid batteries of the present invention product, the conventional product, and the comparative product.

FIG. 6 shows the initial capacity of a lead-acid battery of the present invention, the conventional product, and the comparative product when discharged at a constant current, and the initial capacity of the conventional product is 10
It is a diagram showing discharge capacity when expressed as 0%.

[Explanation of symbols]

1 ... Current collector, 2 ... Primary particle, 3 ... Primary particle active material layer, 4
... secondary particles, 5 ... secondary particle active material layer.

Claims (2)

[Claims] 1. A lead storage battery having a positive electrode plate using a lead alloy as a current collector, wherein a primary particle active material layer made of primary particles of an active material is provided around the positive electrode plate in contact with the current collector. A lead storage battery, wherein a secondary particle active material layer composed of secondary particles in which primary particles of an active material are densely aggregated is provided outside the primary particle active material layer. 2. A total of 0.1 μm is provided between the active material particles forming the primary particle active material layer and the secondary particle active material layer.
Pore with a diameter of m or less is 0.03 ml / g or more, and 0.5 μm
The lead acid battery according to claim 1, wherein pores having the above diameter are present in an amount of 0.06 ml / g or more.