JPH04363872A - Sealed lead-acid battery - Google Patents

Abstract

PURPOSE:To reduce the weight, extend the life and reduce the cost of a sealed lead-acid battery by using an expanded grating as a positive electrode, charging and disposing a silica fine powder in the clearance with a negative electrode plate and around the electrodes, and impregnating and holding a sulfuric acid electrolyte therein. CONSTITUTION:A general Pb-Ca alloy sheet containing 0.7-1.5wt.% of Sb, 0.02-0.12wt.% of Ca, and 0-1.0wt.% of Sn is expanded to form an expanded grating, and a positive electrode active material is charged therein to form a positive electrode plate 1. The Pb alloy for a negative electrode grating is a general Pb-Ca alloy containing 0.05-0.12wt.% of Ca and 0-0.15wt.% of Sn, and the grating is formed by expanding the allay sheet. Small projections 3 are dispersively arranged on a separator 3. The positive and negative electrode plates and the separator are laminated to form an electrode plate group, which is inserted in a battery jar, and a silica fine powder 8 is charged therein. The powder 8 is fixed by a foamed resin plate 9. The battery jar is sealed by a lid 12, and a necessary amount of a sulfuric acid electrolyte is impregnated in and held by the fine powder and the positive and negative electrode plates. According to this constitution, no deformation is caused even if the expanded grating is used in the positive electrode, and a light-weighted, long-lived, and inexpensive sealed Pb storage battery can be provided.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvements in sealed lead-acid batteries.

0002

[Conventional technology and its issues] Currently, lead-acid batteries are used for automobiles,
It is widely used in all fields including industrial use. Light weight, no maintenance (sealing), and cost reduction are latent demands from the market.

[0003] In order to reduce the weight, for example, the grid is made lighter. Casting methods and expanding methods are generally widely used to manufacture grid bodies for paste-type electrode plates.

[0004] Casting involves pouring molten lead into a mold and solidifying it to create a lattice, so relatively thick lattices are easy to manufacture, but thin lattices are difficult to manufacture, resulting in poor productivity and low weight. It has the disadvantage of being difficult to change.

[0005] The expanding method is a method in which a part of a continuous lead alloy sheet is expanded into a mesh shape to create a lattice.
Weight reduction is possible by using a thin sheet. Also,
This is a manufacturing method with extremely high productivity and low cost, as grid formation and active material filling can be performed continuously.

[0006] However, since the expanded lattice has a structure in which sheets are expanded, it has a fatal flaw in that it has low mechanical strength and is easily deformed. The positive electrode of a lead-acid battery is susceptible to deformation of the lattice due to corrosion of the lattice and expansion and contraction of the active material due to charging and discharging. Therefore, when a life test is performed using an expanded lattice for the positive electrode of a lead-acid battery, the life may end prematurely due to dropout of the active material or short circuit due to deformation of the lattice. On the other hand, since the negative electrode is placed at a reducing potential, it does not undergo corrosion like the positive electrode, and is less likely to deform. For these reasons, the expanded lattice is generally not used for the positive electrode, which is easily deformed, but is often used only for the negative electrode.

[0007] In order to use the expanded lattice for the positive electrode,
Some proposals have been made, such as pasting metal foil made of lead-antimony alloy or lead-tin alloy onto a lead alloy sheet, but this basically does not prevent deformation, and batteries using expanded lattice as the positive electrode have short lifespans. The drawback of limited lifespan has not yet been resolved.

On the other hand, two types of sealing means are currently in practical use: a retainer type and a gel type. In both cases, oxygen gas generated during battery charging is absorbed by the negative electrode, thereby eliminating the loss of electrolyte.

In the retainer type, a mat-like separator (glass separator) made of fine glass fiber is inserted between the positive electrode plate and the negative electrode plate, and this holds the sulfuric acid electrolyte necessary for discharge and isolates the two electrodes. In recent years, it has become widely used as a backup power source for portable equipment and computers, taking advantage of its characteristics such as no maintenance, no leakage, and no positioning.

However, on the other hand, there are many factors that increase the manufacturing cost of the battery, such as the high cost of the glass separator and the need to press the electrode plate group strongly and increase the strength of the battery case. They have drawbacks such as inferior low rate discharge performance compared to certain batteries (hereinafter referred to as liquid batteries), which is an obstacle to the widespread use of this type of sealed battery.

On the other hand, although the gel type is cheaper than the retainer type, it has the disadvantage that its battery performance is inferior to the liquid type and retainer type. In both the retainer type and gel type, when an expanded lattice is used for the positive electrode, the lifespan is short due to the reasons mentioned above.

[0012] From the above, in order to develop a battery that satisfies the requirements of being lightweight, sealed, and low cost, it is most important to have a structure that allows the use of an expanded lattice for the positive electrode and a low-cost sealing method. This had become an issue.

[0013]

[Means for Solving the Problems] Even when an expanded lattice is used as a positive electrode, the above-mentioned problems can be solved by developing a sealing method that can prevent deformation of the expanded lattice. Therefore, by filling the area around the electrode plate with a fine powder such as silica that has a liquid-retaining property, it compresses the electrode plate and prevents it from deforming.Furthermore, by having this fine powder hold the electrolyte, it is possible to create a hermetic seal. The battery structure is characterized by the fact that it is thin.

[0014]

EXAMPLES The present invention will be explained below based on examples. FIG. 1 is a schematic diagram showing a sealed lead-acid battery according to the present invention. The positive electrode plate 1 is a positive electrode plate in which an expanded lattice prepared by expanding a sheet of an antimony-free lead alloy or a lead alloy containing a small amount of antimony is filled with a positive electrode active material. Antimony-free lead alloys include calcium 0.02~
A common lead-calcium alloy containing 0.12% by weight and 0-1.0% by weight of tin can be used.

Since the silica fine powder used as the electrolyte holder in the present invention has the property of adsorbing antimony, it is possible to use a lead-antimony alloy for the lead sheet. Lead-
When an antimony-based alloy is used, the antimony content is 0.7 to 2.0% by weight, particularly 0.7 to 2.0% by weight.
1.5% by weight is preferred.

The negative electrode plate 2 is manufactured by filling a lattice made of antimony-free lead alloy with an ordinary negative electrode paste containing an antishrink agent such as lignin or barium sulfate. The lead alloy of the negative electrode grid contains 0.05 to 0.12% by weight of calcium and 0% of tin.
Common lead-calcium based alloys containing ~0.5% by weight can be used. The negative electrode grid may be a cast one, an expanded grid made of a lead alloy sheet, or a punched grid.

3 is a synthetic separator inserted between the positive electrode plate and the negative electrode plate. Although any separator can be used as long as it is thin, porous, and has low electrical resistance, separators with too small pore diameters are not preferred because they are difficult for gas to pass through.

Note that protrusions 4 are provided on one or both sides of the separator 3. In a sealed lead-acid battery that uses powder as an electrolyte holder, the powder must be uniformly filled between the positive and negative electrode plates, so these protrusions are provided to maintain a constant spacing between the electrode plates. be.

These protrusions can be easily formed by applying hot melt resin intermittently in dots or lines using a hot melt gun to a rolled separator band-like sheet. Since the pores of the separator are blocked and ion conductivity is lost in the portion where the projections are provided, increasing the area occupied by the projections is not preferable in terms of battery performance. The total area of the protrusions on the separator should be kept to at most 1% or less.

For this reason, in order to maintain a constant distance between the positive and negative electrode plates, it is preferable to provide small projections in a dispersed manner. In this example, protrusions with a diameter of about 2 mm and a height of 1.2 mm were provided on one side of a synthetic separator with a thickness of 0.25 mm so that the protrusions accounted for about 0.7% of the area of the separator.

The above-described positive electrode plate, negative electrode plate, and separator provided with protrusions are stacked, and the positive and negative electrode plates are separately welded to form an electrode plate group, which is inserted into the battery case 5. With conventional glass separators, it is very difficult to insert the battery into the battery case because the electrode plates must be strongly pressed, but with the present invention, there is no need to press the electrode plates, so insertion is easy. It is.

After inserting the electrode plate group into the battery case, fine silica powder 8 is filled. In this example, the silica fine powder has a primary particle diameter of 10 to 40 millimicrons and a specific surface area of 100 to 1.
50 m2 /g of hydrated silicon dioxide (SiO2 /nH2
O) A powder in which fine particles aggregate to form secondary particles of 50 to 200 microns, and the angle of repose is 25 to 30.
A powder with good fluidity was used.

[0023] Since the powder has excellent fluidity, filling the battery container with the powder is carried out at a gravitational acceleration of 2 to 4 G and an amplitude of 1 to 2.
By applying vibration of mm, dense filling can be achieved in a short time. Also,
This powder is industrially mass-produced, so it is very inexpensive and easily available. It is preferable to fill the powder to such an extent that the positive electrode strap 6 and negative electrode strap 7 of the electrode plate group are just buried.

[0024] Next, a foamed resin plate 9 having open cells was inserted above the powder to fix the powder layer. Since the powder used in the present invention has high fluidity, if the powder 8 is not fixed with the foamed resin plate 9, the powder particles will easily move and create cavities in the powder layer. This is particularly likely to occur when pouring sulfuric acid electrolyte into an uncharged battery or during gassing during initial charging. If a cavity is created in the powder layer, the electrolyte will not be retained in that part, so the active material will no longer work and the desired battery performance will not be achieved. Fixation of the powder bed is very important. After the electrode plate group is housed and filled with powder, the powder layer is fixed by the method described above, and then the battery case 5 and the battery case cover 12 are bonded or welded to complete an uncharged battery.

Reference numeral 13 is an exhaust plug integrated with the battery case lid 12, and 14 is an exhaust valve that opens when the internal pressure of the battery increases and closes when the pressure decreases. The exhaust valve 14 may be any commonly used valve such as a cap valve, ring valve, or plate valve. The exhaust valve may be attached after pouring sulfuric acid electrolyte into an uncharged battery, or may be attached after initial charging. However, if the battery is charged and then installed, it must be installed immediately after charging is complete.

Next, the results of a life test of the sealed lead-acid battery according to the present invention will be explained. The battery used in the test was a 12V automotive sealed lead-acid battery with a nominal capacity of 25Ah. Table 1 shows the contents of the test battery.

[0027]

[Table 1]

Battery No. As shown in Fig. 2, the expanded lattice used in 1 and 4 was made by expanding a lead sheet made of a lead-calcium-tin alloy with a thickness of 1.2 mm into a mesh shape to make the lattice thickness 1.6 mm. used. Battery No. 2
The expanded grid used in , 5 is a lead wire with a thickness of 1.2 mm.
This is a similar development of a lead sheet made of antimony alloy. Battery No. The cast grid used in 3 and 6 has a thickness of 1
．． A 6 mm piece was produced using a lead-calcium-tin alloy by a conventional method. The weight of the expanded grid was approximately 50% lighter compared to the cast grid.

For the negative electrode grid, an expanded grid having the shape shown in FIG. 2 made of a lead sheet made of a lead-calcium-tin alloy and having a thickness of 0.6 mm was used for each battery. Regular positive and negative electrode active materials were used, and dilute sulfuric acid with a specific gravity of 1.30 was used as the electrolyte. After these batteries were charged, they were subjected to a life test according to JIS D-5301, and the change in discharge capacity was examined, and the life was determined to have expired when the capacity reached 70% of the initial capacity.

Table 2 shows a comparison of battery weight and life cycle (each value of battery No. 6 was set as 100).

[0031]

[Table 2]

[0032] The battery weight is determined by the glass separator (battery No.
．． 4, 5, 6) than silica fine powder (Battery No. 1, 2).
, 3) was slightly heavier. This is because the silica fine powder is filled around the electrode plate. In addition, by changing the positive electrode grid from a cast grid to an expanded grid,
The weight of the battery has been reduced by approximately 10%. This is because the positive electrode grid accounts for a very large percentage of the total weight of the battery, about 20%. The battery weight of the batteries of the present invention (Battery Nos. 1 and 2) is as follows. It is 92% lighter than 6, which is about 10% lighter.

Battery No. Assuming that the lifespan of battery No. 6 is 100, retainer type battery No. 6 uses an expanded grid of Pb-Ca alloy as the positive electrode grid. 4 is 64, a retainer type battery No. 64 using an expanded grid of Pb-Sb alloy. 5 is 55,
It had a fairly short lifespan.

Battery No. After dismantling 4, 5, and 6,
In all batteries, the positive electrode lattice was significantly deformed, and short circuits were observed due to falling or elongation of the positive electrode active material. Especially battery no. Although the lifespan of samples 4 and 5 was short, the elongation of the positive electrode expanded lattice was extremely large. Furthermore, battery N
o. 5, the electrolyte in the battery was almost gone. This is thought to be because Sb was deposited on the electrode plates and water decomposition within the battery was promoted.

On the other hand, battery No. 1 according to the present invention uses an expanded lattice for the positive electrode lattice and uses fine silica powder for the electrolyte holder. The lifespan of batteries No. 1 and 2 is 190 and 210, although they use an expanded grid. 6
Approximately twice that of battery No. It was 3 to 4 times that of 4 and 5.

Battery No. When samples 1 and 2 were disassembled, the deformation of the positive electrode expanded lattice was small despite the long life. This is thought to be because the entire electrode plate group including the positive electrode plate was compressed by the silica fine powder around it, and as a result, deformation of the positive electrode plate was suppressed.

Battery No. Although battery No. 2 used a Pb-Sb alloy, battery No. No depletion of the electrolyte as in Example 5 was observed. This seems to be because the silica fine powder adsorbed antimony eluted from the positive electrode lattice, suppressing the precipitation of antimony onto the negative electrode plate. Battery No. 2 is battery number. The reason that the lifespan was longer than that of No. 1 is thought to be because the antimony contained in the positive electrode lattice reduced the deterioration of the positive electrode active material.

Battery No. 1 uses a cast grid as the positive electrode grid and fine silica powder as the electrolyte holder. The lifespan of 3 is 210
and battery no. A little longer than 1, battery no. It was the same as 2. However, when considering comprehensively including battery weight and cost, battery No. 1 of the present invention. 1 and 2 are better.

In the battery of the present invention, since an expanded grid is used instead of a cast grid, and silica fine powder is used instead of a glass separator, the battery manufacturing cost can be significantly reduced.

This time, a 1.2 mm thick lead sheet expanded as shown in Figure 2 was used as the positive electrode expanded lattice, but the lattice shape and the thickness of the lead sheet will vary depending on the type of battery, application, and
Various types can be used depending on the purpose.

[0041] Currently, the rotary type and reciprocating type are the mainstream methods for manufacturing expanded gratings.
In both cases, a part of a continuous lead alloy sheet is developed into a mesh shape and cut to create a grid as shown in FIG. Figure 3 shows a schematic diagram of the developed part, and the lattice shape can be roughly divided into how to make increments, increment width, X (width of squares),
It is determined by Y (vertical width of the square). By changing these, grids of various shapes can be produced.

The lattices shown in FIGS. 4 and 5 have X=Y, X<
By setting Y, H (height of the grating) is made larger than in FIG. The grid shown in FIG. 6 is designed to reduce the ohmic loss of the grid by changing the value of Y between the upper and lower parts of the grid to make the upper squares denser.

[0043] In addition, gratings have also been manufactured in which the increments at the upper and lower portions of the grating are increased to reduce ohmic loss and improve grating strength. In the lattice shown in FIG. 7, the grid has a shape close to a square by changing the way the increments are made.

Regarding the thickness of the lead sheet, in applications where weight reduction is required, such as batteries for electric vehicles, if a thin lead sheet is used, a light battery with excellent longevity can be produced at low cost. Furthermore, in applications where cost reduction is more important than weight in large-capacity batteries such as those used in industrial applications, the use of thicker lead sheets can provide a battery that satisfies the requirements. Furthermore, in the case of small sealed lead-acid batteries for home appliances, etc., there is a strong demand for weight reduction, long life, and cost reduction, making the present invention extremely effective.

As shown above, battery weight, life performance,
The battery of the present invention was excellent in all respects including battery manufacturing cost. This time, we conducted tests for automobiles, but as mentioned above, the present invention can be used for all kinds of sealed lead-acid batteries, including those for electric cars, industrial uses, and home appliances.
Even in that case, similar effects such as weight reduction, longer life, and lower cost can be obtained.

[0046] In the above examples, the test was conducted using fine silica powder, but any fine powder that is acid resistant and has a large specific surface area and porosity can provide the same effects as fine silica powder.

[0047]

Effects of the Invention As is clear from the above embodiments, the sealed lead-acid battery according to the present invention uses an expanded lattice for the positive electrode, and fills the gap between the positive electrode plate and the negative electrode plate and the periphery of the electrode plate with fine silica powder. The fine powder and the positive and negative electrode plates are impregnated with and retained in the amount of sulfuric acid electrolyte required for charging and discharging, making it lighter, longer lasting, and lower cost than conventional sealed lead-acid batteries. , its industrial value is enormous.

[Brief explanation of the drawing]

[Fig. 1] Cross-sectional view of main parts of a sealed lead-acid battery according to the present invention

[Figure 2] Diagram showing the expanded lattice used in the present invention

[
Figure 3: Schematic diagram of the expanded portion of the expanded lattice

[Figure 4] X=
Example of expanded lattice with Y

[Figure 5] Example of expanded lattice with X<Y

[Figure 6] Example of an expanded lattice with different Y values at the top and bottom of the lattice

[Figure 7] Example of an expanded lattice whose grid shape is close to square

[Explanation of symbols]

1 Positive electrode plate 2 Negative electrode plate 3 Separator 4.Protrusion 5 Battery case 6 Positive electrode strap 7 Negative electrode strap 8 Powder 9 Foamed resin board 10 Paul 11 Inter-cell connection 12 Battery case lid 13　Exhaust plug 13 Exhaust valve

Claims (1)

[Claims] Claim 1: In a sealed lead-acid battery in which oxygen gas generated during charging of the battery is absorbed by the negative electrode, an expanded lattice is used for the positive electrode, and silica or the like is used in the gap between the positive electrode plate and the negative electrode plate and around the electrode plate. 1. A sealed lead-acid battery, characterized in that fine powder is filled and arranged, and the fine powder and positive and negative electrode plates are impregnated and retained with a sulfuric acid electrolyte in an amount necessary for charging and discharging.