JP2007018820A - Sealed lead-acid battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sealed lead-acid battery capable of improving a cycle life characteristic of the battery by preventing softening and falling of an active material becoming a life factor of a positive electrode in a cycle use application, in a sealed lead-acid battery. <P>SOLUTION: In this sealed lead-acid battery composed by using an electrode plate formed by filling a lattice substrate formed of lead or a lead alloy with an active material, when it is assumed that each square area of the lattice substrate of the positive electrode and that of the negative electrode are S<SB>1</SB>and S<SB>2</SB>, respectively, S<SB>1</SB><S<SB>2</SB>is satisfied; and the square area S<SB>1</SB>of the lattice substrate of the positive electrode is set to 50-90% of that of the negative electrode. Preferably, the square area S<SB>1</SB>of the lattice substrate of the positive electrode is set to 50-100 mm<SP>2</SP>and the square area S<SB>2</SB>of the lattice substrate of the negative electrode is set not greater than 150 mm<SP>2</SP>. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a sealed lead-acid battery used for cycle use that repeats deep charge and discharge.

  Lead-acid batteries are manufactured using positive and negative electrode plates obtained by filling a lattice substrate made of lead or a lead alloy with an active material. Such lead-acid batteries have a long history as well as nickel-cadmium batteries, and even today they occupy the mainstream of storage batteries because of their high reliability due to their stable performance. It continues to be widely used as a power source, a moving power source used for small electronic devices and electric vehicles, or a backup stationary power source that operates in the event of a power failure of a power source such as a computer.

  In recent years, sealed lead-acid batteries that do not require replenishment of electrolyte from the viewpoint of maintenance are becoming mainstream, and such lead-acid batteries are used for cycle use including load leveling in addition to backup power supplies. The penetration rate is expanding rapidly.

  In such sealed lead-acid batteries, a calcium-based alloy material has been used for the positive electrode lattice substrate in recent years from the viewpoint of improving maintenance-free characteristics. However, when a calcium-based alloy is used as the lattice substrate material, an antimony-based battery is used. Compared to the case of using an alloy, there is an advantage that liquid reduction is small and there is no need for regular rehydration, but there is a problem that the positive electrode active material is easily softened and the cycle life is short.

  There are various types of lattice substrates such as cast lattice substrates, punched lattice substrates, and extended lattice substrates. In order to suppress softening of the positive electrode active material, (1) adhesion between the lattice substrate and the active material particles is increased. It is necessary to enhance (2) the adhesion between the active material particles.

  For this reason, it is conceivable to increase the active material holding power by making the grid of the grid substrate filled with the active material fine. However, if the grid is made fine, the number of grid bars constituting the grid increases, and the grid substrate weight increases. This increases the battery's weight efficiency.

  Therefore, it is conceivable to reduce the thickness (cross-sectional area) of the lattice beam. However, if the thickness of the lattice beam is reduced, the lattice is easily broken due to elongation due to corrosion, and at the same time, the active material is easily removed from the lattice. Cause the problem.

  Therefore, the present invention provides a sealed lead-acid battery that can improve the cycle life characteristics of the battery by preventing softening and dropping of the active material, which is the cause of the life of the positive electrode in cycle-use applications. It is for the purpose.

The present invention relates to a sealed lead-acid battery configured by using an electrode plate obtained by filling a lattice substrate made of lead or a lead alloy with an active material, wherein the grid area of the positive lattice substrate is S ₁ , the square area is taken as S _2, a S 1 _{<S 2,} is obtained as square area S ₁ of the grating substrate in the positive electrode is 50 to 90% of the square area S ₂ of the grating substrate of the negative electrode .

Greater than 90% and no effect on the softening prevention of the positive electrode active material of square area of the grating substrate squares area S ₁ of the grating substrate of the positive electrode negative electrode, also is possible to ensure the rated capacity as less than 50% and the battery This is because, when the grid bars when the grid is less than 50% are made thin so as to secure a predetermined active material filling space, the grid bars are easily corroded.

Further, if the grid area S ₁ of the positive grid substrate is larger than 100 mm ^{2, the} amount of the active material falling off increases, and even if it is smaller than 50 mm ² , the active material fall-off preventing effect is saturated. The cell area S ₁ is preferably 50 mm ² or more and 100 mm ² or less.

Furthermore, if the grid area S ₂ of the negative grid substrate is larger than 160 mm ² , the rate of occurrence of frame dropping after the grid substrate is filled with the active material paste increases, so it is preferable to keep it within 150 mm ² .

  Although it does not specifically limit as a positive electrode grating | lattice concerning this invention, It is preferable to set it as the alloy composition shown below. This is because when the grid area of the grid is reduced, the space for filling the active material inevitably disappears. To compensate for this, it is necessary to make the grid bars constituting the substrate thinner. However, if the grid bar is thinned, the life of the grid bar tends to be reached early due to corrosion of the grid bar. Therefore, a high corrosion resistance alloy is used. As a result, the strength can be maintained even when the lattice bar becomes thin. Specifically, as the material for the positive electrode lattice substrate, calcium is 0.02 wt% or more and less than 0.05 wt%, tin is 0.4 wt% or more and 4.0 wt% or less, and aluminum is 0.04 wt%. It is preferable to use a lead-based alloy for a lead-acid battery that is not more than wt%, barium is not less than 0.002 wt% and not more than 0.014 wt%, and the balance is lead and inevitable components.

  As materials for the positive electrode lattice substrate, calcium is 0.02 wt% or more and less than 0.05 wt%, tin is 0.4 wt% or more and 4.0 wt% or less, and aluminum is 0.04 wt% or less. Barium is 0.002 wt% or more and 0.014 wt% or less, 0.005 wt% or more and 0.07 wt% or less of silver, 0.01 wt% or more and 0.10 wt% or less of bismuth , At least one selected from 0.001% to 0.05% by weight of thallium, and / or 0.01% to 0.1% by weight of copper, potassium, lithium, magnesium, sodium It is preferable to use a lead-based alloy for a lead storage battery in which at least one selected from phosphorus, antimony, selenium, and tellurium, with the balance being lead and inevitable components.

  According to the present invention, in a sealed lead-acid battery, it is possible to improve the cycle life characteristics of the battery by preventing softening and falling off of the active material, which is a life factor of the positive electrode in cycle use applications.

  The sealed lead-acid battery is manufactured as follows. First, prepare a positive grid substrate and a negative grid, and fill each grid of these grid substrates with an active material kneaded into a paste containing a predetermined amount of water and dilute sulfuric acid. Each positive and negative electrode plate is created.

  Next, these positive and negative electrode plates are laminated mainly via a retainer mat made of glass fiber to form an electrode plate group composed of, for example, three positive electrode plates / four negative electrode plates. The electrode plate group is incorporated in the battery case so as to have a predetermined group pressure.

  Next, the same polarity ear group of the electrode plate group is strap-welded by a conventional method, and at the same time, a terminal is formed. Thereafter, a lid is put on the opening of the battery case and bonded, and a predetermined amount of electrolyte is injected into the battery case and sealed. Thereafter, the battery case is formed to form a sealed lead-acid battery.

  With such a technique, the sealed lead-acid batteries (Examples 1 to 9) of the present invention and the sealed lead-acid batteries of Comparative Examples (Comparative Examples 1 to 3) as shown in Table 1 below were manufactured.

In the sealed lead-acid batteries of Examples 1 to 9 of the present invention, the grid area S ₁ of the positive grid substrate is smaller than the grid area S ₂ of the negative grid substrate (S ₁ <S ₂ ), and the positive grid substrate square area S ₁ is a lead storage battery is in the 50-90% range squares area S ₂ of the grating substrate of the negative electrode.

The sealed lead-acid batteries of Comparative Examples 1 and 2 are lead-acid batteries in which the grid area S ₁ of the positive grid substrate is larger than or the same as the grid area S ₂ of the negative grid substrate (S ₁ ≧ S ₂ ). In the sealed lead-acid battery, the grid area S ₁ of the positive grid substrate is smaller than the grid area S ₂ of the negative grid substrate (S ₁ <S ₂ ), but the grid area S ₁ of the positive grid substrate is the negative grid. in 40% of the square area _{S 2} of the substrate, a lead-acid battery is out of the range of 50-90%.

  In each of the sealed lead-acid batteries, the positive electrode grid and the negative electrode grid are each made of a calcium-based alloy, and the electrode plate group is incorporated in the battery case so as to have a group pressure of 20 kPa in the battery case, and is sealed with 2 V and a rated capacity of 7 Ah. It is assembled as a lead-acid battery. Usually, the electrode plate group is incorporated so as to have a group pressure exceeding 20 kPa. However, in order to make it easy to confirm the adhesion between the positive electrode lattice substrate and the active material, the active electrode of the positive electrode lattice substrate is intentionally used. Incorporation was performed at a group pressure close to a low pressure at which softening of the material (softening of the positive electrode) easily occurred.

  Next, two levels of each of the sealed lead-acid batteries manufactured in this way are placed in a constant temperature bath at 25 ° C. and discharged; 0.25 C × 2 hours (DOD 50%), charged; 0.25 C (90%) + 0 A cycle test consisting of .15C (15%) and a charge amount of 105% was conducted, a capacity test was conducted at 0.1C every 100 cycles, and the point in time when 70% of the rated capacity was cut off was defined as the life (average of two). . The results are shown in Table 1.

  In addition to the above cycle test, the amount of the active material falling off the positive grid substrate used for each lead storage battery was measured, and the results are shown in Table 1. This measurement is a measurement of the ratio of the amount of dropout to the total amount of active material when the active material filled in the positive electrode lattice substrate is dropped and dried 10 times from a height of 30 cm after aging and drying. The density of the active material filled in the positive electrode grid substrate is 4.2 g / cc.

Those of Comparative Example 1, square area S ₁ of the grating substrate in the positive electrode is larger than the square area S ₂ of the grating substrate of the negative electrode, those of Comparative Example 2, the grating substrate squares area S ₁ of the grating substrate of the positive electrode negative electrode of which it is the same as the square area S _2, as is apparent from such Table 1 with lead-acid batteries, many falling amount of the active material of the grating substrate in the positive electrode, a short cycle life.

On the other hand, in Examples 1 to 9, the grid area S ₁ of the positive grid substrate is smaller than the grid area S ₂ of the negative grid substrate, and the grid area S ₁ of the positive grid substrate is the negative grid substrate. It is in within 50-90% of the range of square area _{S 2.} In such a lead storage battery, it can be seen that, compared with Comparative Examples 1 and 2, the amount of the active material falling off the positive grid substrate is small and the cycle life is long.

In the comparative example 3, the grid area S ₁ of the positive grid substrate is smaller than the grid area S ₂ of the negative grid substrate, but the grid area S ₁ of the positive grid substrate is the grid area S ₂ of the negative grid substrate. Of 40%, out of the range of 50 to 90%.

In this case, too small squares area S ₁ of the grating substrate in the positive electrode is not expected rated capacity is obtained, it is impossible to manufacture a lead-acid battery rated. In this case, if the lattice beam is made narrow in order to obtain the same active material filling space as that of other levels, the problem of corrosion of the thin lattice beam will occur.

  By the way, if the grid of the negative grid substrate is too large, a so-called drop-off phenomenon is likely to occur. This drop-off is when the active material in the grid substrate is filled with the active material and the active material before entering the preheating drying furnace is relatively soft, and the active material of a part of the grid substrate is exactly the same as the grid. A phenomenon that falls off.

According to experiments, when the area of the grids of the negative grid substrate is 160 mm ² or more, the rate of occurrence of this frame drop increases. This experiment was performed by calculating the ratio of the number of grid substrates in which a frame drop occurred per 100 negative grid substrates. The grid substrate in which the frame drop occurs when the grid area of the grid substrate is 160 mm ^2. The ratio was as high as 4.5%. Therefore, it is preferable that the area of the grid of the negative grid substrate is 150 mm ² or less.

Claims (3)

In a sealed lead-acid battery configured using an electrode plate formed by filling a grid substrate made of lead or a lead alloy with an active material, the grid area of the positive grid substrate is S ₁ , and the grid area of the negative grid substrate is S ₂ , S ₁ <S ₂ , and the grid area S ₁ of the positive grid substrate is 50 to 90% of the grid area S ₂ of the negative grid substrate. ^2. The sealed lead-acid battery according to claim 1, wherein the grid area S ₁ of the grid substrate of the positive electrode is 50 mm ² or more and 100 mm ² or less. Sealed lead acid battery according to claim 1 or 2, characterized in that square area S ₂ of the grating substrate of the negative electrode is 150 mm ² or less.