JPH0654681B2 - Sealed lead acid battery - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a sealed lead acid battery, and more particularly to a high performance sealed lead acid battery having excellent overcharge life performance and a constant electrode plate pitch.

[Prior Art] As a form of an anode of a storage battery, a paste type electrode plate and a clad type electrode plate have been conventionally known. In recent years, it has been attempted to hermetically seal a storage battery, and the paste-type hermetically sealed battery is made by absorbing free electrolytic solution flowing into a separator mainly composed of fine glass fibers having an average diameter of 2 μm or less between electrode plates. It is configured.

In this sealed battery, the liquid weight is smaller than that of the conventional battery, and therefore the specific gravity of the electrolyte must be increased. as a result,
Self-discharge tends to increase, and in addition, non-reducing lead sulfate is likely to be generated in the cathode active material.

In this way, even in the case of batteries with high specific gravity electrolyte, the sulfuric acid content in the battery is self-discharging, which is useless for the battery, depending on the stock period after manufacture, the transportation and storage conditions after shipment from the factory, and the period. Is consumed, and as a result, the open circuit voltage of the battery decreases. The internal resistance of the battery also gradually increases, and the discharge performance of the battery tends to decrease.

Therefore, there is a limit to increasing the specific gravity of the electrolytic solution, so the amount of the liquid should be increased as much as possible. Also, since the amount of electrolyte is kept extremely low, if the electrode plate and separator do not come in contact with each other with a certain degree of tightness, the movement of ions necessary for battery charging / discharging will not occur. You will not be able to do enough through the inside. Because of this fear, it is safer to make the pressure tighter and it becomes stronger than necessary, resulting in poor productivity in the tank container assembly.
Due to the variation in the thickness of the separator, the porosity of the separator corresponding to the local and local active material surfaces of the electrode plate is also affected, and the porosity decreases where the pressure is applied strongly. The implications of are mixed up. This causes variations in the discharge performance of the battery.

It is preferable that the separators in contact with both sides of the anode plate are uniformly provided with sufficient porosity for allowing the electrolyte solution to be required for repeated use of discharging and charging the battery.

By the way, in the case of a sealed lead-acid battery, when the battery is charged, the oxygen gas generated from the anode plate is absorbed into the cathode active material by a chemical reaction. No reaction will occur.

It is known that the oxygen gas generated from the anode through the thin film of the electrolyte solution on the surface of the cathode active material chemically reacts with the cathode active material, and it is interpreted that this chemical reaction becomes the main reaction and gas absorption progresses. It However, in the study of the present inventor, the chemical reaction between the oxygen gas and the cathode active material through the liquid film is extremely slow motion, only a small amount reacts, it cannot be the main reaction, and the main reaction is This occurs rapidly when the dry and fresh cathode active material reacts with oxygen gas, which has an appropriate amount of moisture, in an atmosphere of an appropriate temperature to react.

Also, in sealed lead-acid batteries, the electrolytic solution is limited and does not have a free electrolytic solution, so it is necessary to avoid using it in the overcharge region (which suppresses hydrogen gas generation). It has adopted the voltage charging method. Therefore, under conditions other than inappropriate temperature and charging conditions, oxygen gas having a capacity higher than the oxygen gas absorption capacity of the cathode plate is generated and accumulated, and the internal pressure of the battery rises. In this case, at the same time as the operation of the safety valve, the moisture in the electrolytic solution diffuses to the outside of the battery as much as the gas, and the amount of the electrolytic solution decreases. In addition, the capacity of the positive and negative electrode plates was lowered due to the reduced adhesion between the surface of the active material and the separator made of a fine glass fiber mat. Therefore, in a sealed lead-acid battery, the oxygen gas absorption capacity at the cathode plate becomes the dominant factor in battery life,
There is also a drawback that excellent life performance cannot be obtained.

By the way, in the lead storage battery in which the electrode plate group is immersed in the electrolytic solution, heat generation during charging mainly occurs due to a reaction in which oxygen gas and hydrogen gas are generated by electrolysis of water in which the electrode plate is completely charged. However, a sealed lead that uses a mechanism in which the oxygen gas generated from the anode plate and the cathode plate react during charging with an electrolyte containing dilute sulfuric acid as the main component and substantially no free electrolyte. In the storage battery, the oxygen gas generated from the positive and negative electrodes generates a large amount of heat when reacting with the cathode plate.
This reaction is unlikely to occur in the cathode plate completely covered with the electrolytic solution and often occurs in the semi-dried portion, so that the temperature rise tends to be locally large on the outer surface of the end cathode plate of the electrode plate group. For this reason, there is also a drawback that the synthetic resin plate or the synthetic resin battery case abutting on the electrode plate group may be deformed or damaged as a dimension adjustment.

As described above, in the conventional sealed lead-acid battery, the electrode plate intervals are likely to be uneven. Moreover, the amount of the electrolytic solution tends to be insufficient or uneven due to the pressure.

Since the oxygen absorption capacity of the cathode plate governs battery life,
Life is short. In particular, it is difficult to keep the surface of the cathode plate dry.

The battery case may be deformed and damaged due to the heat generated in the battery.

There is a drawback, and the solution is desired.

With regard to the problems (1) to (4), it has been proposed that a specific porous plate be provided outside the cathode plate to improve the oxygen absorption capacity of the cathode plate and prolong the battery life (JP-A-63-63). 155259). However, there is a complaint that the cathode plate area for the non-hole portion of the perforated plate is not utilized.

With regard to the above, it is proposed that a liquid absorber having a small pore size is provided outside the electrode plate group to absorb heat and prevent deformation or damage of the battery case. (JP-A-63-152
162). However, it is difficult to make the surface of the cathode plate dry by this method.

[Problems to be Solved by the Invention] As described above, a sealed lead-acid battery capable of simultaneously solving the above-mentioned problems (1) to (3) has not been provided yet, and improvement thereof is strongly desired.

The present invention has been made in view of the above-mentioned conventional circumstances, and can simultaneously solve the above-mentioned problems (1), that is, the electrode plate pitch is constant, withstands pressure, and is excellent in overcharge life performance. It is an object of the present invention to provide a high performance sealed lead acid battery in which the surface of the plate is in a dry state to enhance the gas absorption capacity and there is no problem of deformation of the battery case due to heat generation.

[Means for Solving the Problems] The sealed lead-acid battery of the present invention is a positive electrode plate which is alternately arranged,
The present invention relates to a sealed lead storage battery in which a separator and a cathode plate are provided in a battery case, and the electrode plates at both ends of an electrode plate group including the anode plate and the cathode plate are cathode plates.

In the present invention, the anode plate is mainly composed of glass fibers having an average diameter of 2 μm or less, and is covered with a separator containing ribs made of an acid-resistant thermoplastic resin. This solves the above problem.

Further, in the present invention, the outer surface of the cathode plate at both ends of the electrode plate group is covered with a sheet obtained by bonding glass fibers having an average of 13 to 25 μm with an organic binder.

The sheets on both sides of the anode plate are designed so that when the battery discharges at various rates, they will be able to exert their full potential, and to make the active material on the outside dry and to absorb oxygen easily. Is. The arrangement of thick fibers having a thickness of 13 to 25 μm is sparse, and the above-mentioned problem is solved because the entire area of the cathode plate works effectively, and this problem is also solved because this layer serves as a heat insulating layer.

Hereinafter, the present invention will be described in more detail with reference to the drawings.

FIG. 1 is a schematic sectional view showing a sealed lead acid battery according to an embodiment of the present invention, and FIG. 2 is a perspective view showing an example of a separator used in the sealed lead acid battery of the present invention.

As shown in the figure, the sealed lead-acid battery 1 of the present invention is provided with an anode plate 3 and a cathode plate 4 and a separator 5 arranged alternately in a battery case 2. The electrode plates at both ends of an electrode plate group consisting of the anode plate 3 and the cathode plate 4 (in FIG. 1, an electrode plate group consisting of two anode plates 3A, 3B and three cathode plates 4A, 4B, 4C) are The cathode plates 4A and 4C are used. Anode plate 3A, 3B
Are mainly composed of glass fibers each having a diameter of 2 μm or less, and are covered with separators 5A and 5B containing ribs made of an acid-resistant thermoplastic resin. The outer surfaces of the cathode plates 4A and 4C at both ends of the electrode plate group are covered with sheets 6A and 6B formed by bonding glass fibers having a diameter of 13 to 25 μm with an organic binder.

In FIG. 1, the separator 5 covering the anode plate 4 is
For example, as shown in FIG. 2, ribs 8 made of acid-resistant thermoplastic resin are built in a separator body 7 mainly composed of glass fibers having an average diameter of 2 μm or less.

The separator 5 shown in FIG. 2 is provided with two ribs 8 in a direction orthogonal to the thickness direction of the separator body 7 and in the length direction (vertical direction in the drawing). There is no particular limitation on the number, and it may be three or four or more.

Usually, it is preferable to provide two or three ribs at symmetrical positions. Also, there is no particular limitation on the arrangement direction,
It is preferable to set it at a substantially central position in the thickness direction of the separator body and in an upright direction of the battery (length direction of the separator). Of course, the ribs can be provided in an oblique direction that intersects the width direction or the length direction of the separator. Also,
The ribs do not have to be arranged linearly, and may be curved as long as they are in the plane of the separator.

On the other hand, the glass fibers constituting the separator body 7 are mainly glass fibers having an average diameter of 2 μm or less, preferably 1 μm or less.

Such a separator 5 can be manufactured as follows, for example, using the apparatus shown in FIG.

That is, the glass fiber 20 or the glass fiber 20 mixed with organic fiber as required is fed from the papermaking tank 21 to the papermaking net 22.
As shown in FIG. 3, in the process of supplying and papermaking to the above, hot melt resin 24 is melted from the nozzle 23 in a strip shape at predetermined intervals in the width direction and is supplied in parallel to the press roll 25. Embedded in the paper making mat 26. After the papermaking, it is dried by, for example, a drum dryer.

In the present invention, the thickness of the separator is 0.5 to 3.5 m.
m, rib thickness is 50 to 95% of separator thickness
The volume ratio is preferably about 1 to 5%.

The acid-resistant thermoplastic resin forming the ribs has a viscosity of 1300 to 10 at a melting temperature of 150 to 200 ° C.
A hot melt resin having a Shore hardness of 70 degrees or more, preferably 85 degrees or more at a room temperature of 000 centipoise is preferable. As a preferable example of such a hot melt resin,
Mention may be made of a mixture of ethylene vinyl acetate copolymer resin (“Topco H-017” manufactured by Toyo Ink) and several kinds of attack polypropylene resin.

With hot melt, the diameter of the discharge nozzle can be increased or decreased to easily create ribs with the required diameter.

On the other hand, the sheets 6A and 6B covering the outer surfaces of the cathode plates 4A and 4C at both ends of the electrode plate group are formed by adhering glass fibers having an average diameter of 13 to 25 μm with an organic binder.

The glass fiber constituting the sheet 6 may be a glass fiber manufactured by a wet method having an average diameter of 18 μm to 22 μm and a fiber length of 6 mm to 25 mm, or a dry mat obtained by a felt spreading method. Examples of the organic binder used include acrylic binder and corn starch. The amount of these organic binders used is preferably 10 to 25% by weight of the glass fiber weight.

In the present invention, the sheet 6 has a density of 0.12.
It is preferably about 0.18 g / cm ³ .

Such a sheet is usually preferably a glass mat having a thickness of about 0.3 to 3.5 mm.

In FIG. 1, the total number of the electrode plates is five, but in the actual battery, the number of positive plates + 1 the number of negative plates is provided.

[Operation] In the sealed lead-acid battery of the present invention, since the separator enclosing the anode plate is mainly composed of thin glass fibers having an average diameter of 2 μm or less, the liquid absorption rate and the liquid retention amount are high, and the battery performance is improved. Is effective for. Moreover, since the ribs are built in, the pressure resistance is high, the separator thickness can be kept constant, and therefore the electrode plate spacing can be kept constant.

Further, the sheet covering the outer side cotton of the cathode plate at both ends of the electrode plate group is formed by adhering glass fibers having an average diameter of 13 to 25 μm with an organic binder and has a very low liquid retention rate and porosity. Because it is a high sheet, it does not cover the entire outer surface of the cathode plate, and the cathode plate surface that this sheet is in contact with is not likely to get wet with the electrolyte, and it is in a dry state in some places, so the cathode plate surface can be used The conversion rate can be increased. Therefore, the oxygen absorption capacity of the cathode plate is improved, and the battery life is extended.

Further, the sheet and the electrolytic solution in the sheet can prevent thermal deformation of the battery case due to the heat insulating effect.

[Examples] Examples and comparative examples will be described below.

Example 1 The following were used as the anode plate 3, the cathode plate 4, the separator 5 and the sheet 6, and the sealed lead-acid battery (6V × 6AH) shown in FIG. 1 was assembled.

Anode plate 3 sheets / single cell width = 43 mm Thickness = 3.4 mm Length = 64 mm Cathode plate 4 sheets / single cell width = 43 mm Thickness = 2.4 mm Length = 64 mm Separator width = 53 mm Thickness = 2.0 mm Length = 144 mm Made of glass fiber with an average diameter of 0.8 μm, and as shown in FIG. 2, incorporates two ribs with a diameter of 1.85 mm (“Topco H-017” manufactured by Toyo Ink). . Density 0.14
g / cm ³ sheet Width = 53 mm Thickness = 0.5 mm Length = 62 mm A glass mat in which glass fibers having an average diameter of 19 μm are bonded with an acrylic resin of 15% by weight. With respect to the sealed lead-acid battery having a density of 0.14 g / cm ³ , variations in electrode plate intervals, overcharge life characteristics, etc. were examined, and the results are shown in Table 1 and FIG.
It is shown in FIG.

Comparative Example 1 A sealed lead acid battery was assembled in the same manner as in Example 1 except that a separator having no ribs was used and no sheet was provided.
The comparison results are shown in Table 1, FIG. 4 and FIG.

Figures 4 and 5 show the results of an overcharge test of about 60 months under normal temperature environment (in the figure, temperature indicates room temperature). This is based on the Japan Storage Battery Industry Association standard (SBA3018 overcharge life). When calculated according to the total overcharge (AH) (C ₂₀ ; 20 hour rate capacity), Example 1: 0.00025C ₂₀ × 24h / day × 30 months / month × 60 months = 10.8C ₂₀ or more Comparative Example The experimental result was summarized in the numerical value of 1: 0.00025C ₂₀ × 24 h / day × 30 months / month × 40 months = 7.2 C _{20, and} the overcharge life performance of Example 1 was remarkably improved.

As is clear from Table 1, FIG. 4 and FIG. 5, according to the present invention, variations in electrode plate spacing are reduced, the electrode plate spacing becomes almost constant, and overcharge life performance is significantly improved. Improved.

[Effects of the Invention] As described in detail above, according to the sealed lead-acid battery of the present invention,
Provided is a sealed lead acid battery having a constant electrode plate spacing and therefore excellent battery performance, and having excellent characteristics in which the overcharge life thereof is remarkably long.

[Brief description of drawings]

1 is a schematic cross-sectional view showing a sealed lead-acid battery according to an embodiment of the present invention, FIG. 2 is a perspective view showing an example of a separator used in the present invention, and FIG. 3 is a view showing a separator of the present invention. FIG. 4 is a schematic side view of a suitable apparatus, FIG. 4 is a diagram showing the result of measuring the overcharge life of Example 1, and FIG. 5 is a diagram showing the result of measuring the overcharge life of Comparative Example 1. 1 ... Sealed lead acid battery, 2 ... Battery case, 3 ... Anode plate, 4 ... Cathode plate, 5 ... Separator, 6 ... Sheet.

Claims (1)

[Claims] 1. A sealed lead in which an anode plate, separators and cathode plates arranged alternately are provided in a battery case, and the electrode plates at both ends of an electrode plate group consisting of the anode plate and the cathode plate are cathode plates. In a storage battery, the anode plate is encapsulated by a separator mainly composed of glass fibers having an average diameter of 2 μm or less and having ribs made of an acid-resistant thermoplastic resin, and glass fibers having an average diameter of 13 to 25 μm. A sealed lead acid battery, characterized in that the outer surface of the cathode plate at both ends of the electrode plate group is covered with a sheet bonded with an organic binder.