JP3266918B2 - Sealed lead-acid battery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art At present, two types of sealed lead storage batteries, a retainer type and a gel type, have been put into practical use. In each case, the oxygen gas generated during the charging of the battery is absorbed by the negative electrode, so that the electrolyte is not reduced and the hermetic sealing is achieved.

[0003] In the retainer type, a mat-like separator (glass separator) made of fine glass fiber is inserted between a positive electrode plate and a negative electrode plate, thereby holding a sulfuric acid electrolyte necessary for discharge and isolating both electrodes. In recent years, it has been widely used as a backup power supply for portable devices and computers, taking advantage of features such as maintenance-free, liquid-free, and position-free.

However, on the other hand, there are many factors that increase the production cost of the battery, such as the fact that the glass separator is expensive and the strength of the battery container must be increased due to the need to strongly press the electrode plate group. Such batteries have drawbacks such as inferior low-rate discharge performance as compared with certain batteries (hereinafter, referred to as liquid batteries), which hinders the spread of such sealed batteries.

On the other hand, the gel type is less expensive than the retainer type, but has a drawback that the battery performance is inferior to the liquid type or the retainer type.

In order to solve these drawbacks, a sealed lead-acid battery has been proposed which is neither a retainer type using fine glass fibers nor a gel type using a gel electrolyte. That is, a powder having a high porosity and a large specific surface area, such as silica powder, is used as an electrolyte holding material, and the powder is filled in the gap between the positive electrode plate and the negative electrode plate and around the electrode plate group. It is a sealed lead-acid battery of the configuration.
Silica powder is an inexpensive material that is mass-produced and sold, and has excellent acid resistance and electrolyte retention ability, so it is an excellent powder for use as an electrolyte retention material in this type of sealed lead-acid battery. It can be said that it is a material.

However, problems have been clarified with the progress of experiments on sealed lead-acid batteries using silica powder. If the electrodes are not sufficiently separated, the active material particles penetrate through the gaps between the silica powders, and cause a short circuit, particularly in a battery having a narrow gap between the electrodes, such as for an automobile. In order to prevent this, it is necessary to use an isolator between both electrode plates.

When the granulated silica powder is used as the electrolyte holder, the separator must be used as described above. In addition, the gap holder must be used together to keep the distance between the two electrode plates constant. Must. Hitherto, a method of using a sheet-shaped separator and an interelectrode holder together, and a method of using a separator having a linear rib in a vertical direction have been proposed.
However, in these methods, the space of the electrode plate is divided into several blocks by the inter-electrode holders or ribs located in the vertical direction, so that it is difficult to fill the inside of the battery with the granulated silica powder. The obtained silica granulated powder became uneven. After filling the silica granulated powder and injecting the electrolytic solution, it is conceivable that the lateral movement of the electrolytic solution is hindered and affects the battery performance.

Also, there has been proposed an isolator having a convex portion formed of resin or the like on one or both surfaces. By using this, the above-mentioned problem can be solved. However, since a process of forming a convex portion with a resin or the like on the separator is required, the manufacturing cost is greatly increased. Furthermore, since the convex portion is a hindrance to the battery reaction, an increase in the number of convex portions may have an adverse effect such as a decrease in discharge capacity.

[0010]

According to the present invention, there is provided a sealed lead-acid battery comprising an electrode plate formed by embossing a separator provided with a convex portion on one or both surfaces between a positive electrode plate and a negative electrode plate. And the silica powder filled between and around the electrode plates is fixed, and the sulfuric acid electrolyte is held by the silica powder, the separator and the positive and negative electrode plates.

[0011]

FIG. 1 is a schematic view showing a sealed lead-acid battery according to the present invention. The positive electrode plate 1 is an antimony-free lead alloy or a lead alloy lattice containing a small amount of antimony filled with a positive electrode active material. As an antimony-free lead alloy,
A general lead-calcium alloy containing 0.02-0.12% by weight of calcium, 0-1.0% by weight of tin and a trace amount of aluminum can be used.

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

The negative electrode plate 2 is manufactured by filling a grid using an antimony-free lead alloy with a normal negative electrode paste obtained by adding a shrinkproofing agent such as lignin or barium sulfate. The lead alloy of the negative electrode grid is composed of 0.05 to 0.12% by weight of calcium,
Common lead-calcium based alloys containing .about.0.5% by weight and traces of aluminum can be used. As the negative electrode grid, any of a cast grid, an expanded grid obtained by expanding a lead alloy sheet, and a punched grid can be used.

Reference numeral 3 denotes an isolator inserted between the positive electrode plate and the negative electrode plate and provided with projections 4 intermittently on both surfaces by embossing. Any separator can be used as long as it is thin and porous and has a low electric resistance. However, an insulator having a too small pore diameter is not preferable because the gas hardly permeates. In a sealed lead-acid battery using a powder as an electrolyte holder, since the powder must be uniformly filled between the positive and negative electrodes, such a projection is provided because the interval between the electrodes needs to be kept constant. It is.

FIG. 2 shows an outline of embossing. By continuously passing the belt-like sheet 15 for a separator wound in a roll between the rollers 16 having the protrusions, the protrusions can be easily formed. The separator shown in FIG. 3 is obtained by wet-making inorganic powder, inorganic fiber and organic fiber together with a small amount of binder to form a sheet, and forming hemispherical projections at regular intervals on both surfaces by embossing. It is cut.

The positive electrode plate, the negative electrode plate, and the separator provided with the projections are stacked, and the positive electrode plate and the negative electrode plate are separately welded to form an electrode plate group. In the case of using a conventional glass separator, it is very difficult to insert the electrode group into the battery case because the electrode group must be strongly pressed, but in the present invention, it is not necessary to press the electrode group, so the insertion is easy. It is. After inserting the electrode plate group into the battery case, the silica fine powder 8 is filled.

In this embodiment, the silica fine powder has a primary particle diameter of 10 to 40 millimicrons and a specific surface area of 100 to 15
0 m ² / g hydrous silicon dioxide (SiO ₂ / nH ₂ O) is a powder in which fine particles are agglomerated to form secondary particles of 50 to 200 μm, and have a repose angle of 25 to 30 degrees. Good powder was used. Since the powder is excellent in fluidity as described above, the filling of the powder into the battery container is performed at a gravitational acceleration of 2 to 4 G,
If a vibration having an amplitude of 1 to 2 mm is applied, dense filling can be performed in a short time.

This powder is very inexpensive because it is industrially mass-produced and can be easily obtained. The powder is preferably filled so that the positive electrode strap 6 and the negative electrode strap 7 of the electrode group are just filled.

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 a high fluidity, if the powder 8 is not fixed with the foamed resin plate 9, the powder particles easily move and a cavity is formed in the powder layer. This is particularly likely to occur when a sulfuric acid electrolyte is injected into an uncharged battery or when gassing occurs during initial charging. When a cavity is formed in the powder layer, the electrolytic solution is not held in that portion, so that the active material does not work and the target battery performance cannot be obtained. The fixation of the powder bed is very important. After accommodating the electrode plate group and filling the powder, the powder layer is fixed by the above-described method, and then the battery case 5 and the battery case lid 12 are bonded or welded to complete the uncharged battery.

Reference numeral 13 denotes an exhaust valve integrated with the battery case lid 12, and reference numeral 14 denotes an exhaust valve that opens when the internal pressure of the battery increases and closes when the internal pressure of the battery decreases. The exhaust valve 14 may be any commonly used valve such as a cap valve, a ring valve, and a plate valve. The exhaust valve may be installed after the sulfuric acid electrolyte is injected into the uncharged battery, or may be installed after the first charge. However, when installing after charging the battery, it must be installed immediately after charging is completed.

Next, the results of the capacity test of the sealed lead-acid battery according to the present invention will be described. The battery used for the test was a 12 V automotive sealed lead-acid battery with a nominal capacity of 25 Ah.

Battery No. Reference numeral 1 denotes a battery of the present invention in which an embossed separator is used and silica fine powder is filled. This separator is made by wet-making inorganic powder, inorganic fiber and organic fiber together with a small amount of binder to form a sheet, and cylindrical protrusions of about 2 mm in diameter and about 0.6 mm in height are formed on both sides at regular intervals. It is a thing. The convex portion was formed by continuously passing a belt-like sheet for a separator wound into a roll between rollers having the convex portion. Here, projections having a diameter of about 2 mm and a height of 0.6 mm were provided on both sides of a synthetic separator having a thickness of 0.25 mm so as to be about 0.7% of the area of the separator.

Battery No. Reference numeral 2 denotes a battery filled with silica fine powder using a separator subjected to spot rib processing. The spot rib process is a process in which a resin protrusion is provided on a separator. The projections were formed by intermittently applying a hot melt resin to the strip-shaped sheet for the separator wound in a roll shape using a hot melt gun in a dotted or linear manner. Since the voids of the separator are blocked at the portion where the protrusions are provided on the separator and ion conductivity is lost, it is not preferable in terms of battery performance to increase the area occupied by the protrusions. In this embodiment, the thickness is 0.25.
A protrusion having a diameter of about 2 mm and a height of 1.2 mm was provided on one side of a synthetic separator having a thickness of about 2 mm so as to be about 0.7% of the area of the separator.

In each of the batteries, the positive electrode had a thickness of 1.6 mm.
Was used in a conventional method using a lead-calcium-tin-aluminum alloy.

As the negative electrode grid, an expanded grid made of a lead sheet made of a lead-calcium-tin alloy having a thickness of 0.6 mm was used for all batteries.

As the positive and negative electrode active materials, ordinary ones were used, and a battery case was formed. The specific gravity of the electrolytic solution after formation of the battery case is 1.30.
And Next, the results of the capacity test are shown in Table 2.

[0027]

[Table 2]

The discharge capacity at 25 ° C. and 5 A was the same as that of Battery No. 2 is 2
3Ah, the battery No. 1 was as large as 26 Ah. -15 ° C, 150A discharge capacity was the same for Battery No. Battery No. 2 was 7.4 Ah while Battery No. 2 was 7.4 Ah. 1
Was as large as 7.7 Ah.

Battery No. It is probable that the capacity of the separator No. 2 was small because the separators provided with resin protrusions blocked the pores of the separator by the resin, lost ion conductivity and made it difficult for a discharge reaction to occur. On the other hand, battery No. In the case of using the separator having been subjected to the embossing process of No. 1, it is considered that the capacity was large because the ionic conductivity was not lost even at the projections.

Further, since embossing can be performed at a very low cost as compared with spot rib processing or the like, a sealed lead-acid battery filled with silica fine powder using an embossed separator can be manufactured at low cost.

[0031]

As is clear from the above embodiment, the cost is lower than that of a conventional sealed lead-acid battery.
Its industrial value is enormous.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a sealed lead-acid battery of the present invention.

FIG. 2 is a view schematically showing an embossing method.

FIG. 3 is a diagram of an embossed separator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Positive electrode plate 2 Negative electrode plate 3 Embossed separator 4 Projection 5 Battery case 8 Fine silica powder 9 Foamed resin plate 12 Battery case lid

Claims (1)

(57) [Claims] 1. A sealed lead-acid battery in which oxygen gas generated during charging of a battery is absorbed by a negative electrode, wherein a separator provided with a convex portion on one or both surfaces by embossing is interposed between the positive and negative electrode plates. While storing the electrode group in the battery case,
Fixing the silica powder filled around the electrode plates and the electrode plate
And a sulfuric acid electrolytic solution held by the silica powder , the separator and the positive and negative electrode plates.