JPH02309567A - Sealed type lead storage battery - Google Patents

Abstract

PURPOSE:To improve the battery performance and the service life by forming cathode plates with a glass fiber less than a specific size, covering them with separators with built-in ribs, and covering the both ends of the electrode plate group with sheets which consist of glass fibers made in a specific size. CONSTITUTION:Both ends of an electrode plate group which consists of cathode plates 3 and anode plates 4 are formed of cathode plates 4A and 4C. A cathode plate 3 is formed of a glass fiber of the diameter less than 2mum, it is covered with a separator 5 with a builtin rib of an acid-proof thermal-plastic resin, and the outer sides of the anode plates 4A and 4C are covered with sheets 6 made by attaching glass fibers with the diameter 13-25mum with an organic binder. As a result, the separators 5 have a high liquid absorption rate and a high liquid holding amount to improve the battery performance, and the thickness of them is kept constant by the ribs and the interval between electrode plates is kept constant. Furthermore, the sheets 6 have a low liquid holding rate to improve the oxygen absorbing capacity of the anode plates, and the battery life is extended. Consequently, a storage battery of an excellent performance and a long service life can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a sealed lead-acid battery, and particularly to a high-performance sealed lead-acid battery that has excellent overcharge life performance and a constant plate pitch.

[Prior Art] Paste-type electrode plates and clad-type electrode plates have been known as types of anodes for storage batteries. In recent years, attempts have been made to seal storage batteries, and paste-type sealed batteries have a separator between the electrode plates that is mainly made of fine glass fibers with an average diameter of 2 μm or less, which absorbs any free electrolyte that flows. It is configured.

This sealed battery requires less molding than conventional batteries, so the specific gravity of the electrolyte must be increased. the result,
Self-discharge tends to increase, and in addition, non-reducible lead sulfate is more likely to be generated within the cathode active material.

In this way, even batteries with high-density electrolytes can undergo self-discharge, which is of no use to the battery due to the sulfuric acid content within the battery, depending on the inventory period after manufacture, transportation conditions and storage conditions after shipment from the factory. As a result, the open circuit voltage of the battery decreases. The battery's internal resistance also gradually increases, and the battery's discharge performance tends to decline.

Therefore, since there is a limit to increasing the specific gravity of the electrolytic solution, we want to increase the amount of the electrolyte as much as possible.Also, because the amount of electrolyte is kept extremely low, the contact between the electrode plate and the separator is under considerable pressure. If there is no contact with dust, the movement of ions necessary for charging and discharging the battery through the electrolyte will not be possible. Because of this fear, it is safer to make the pressure dust stronger than necessary, and the productivity of the assembling of the oak case deteriorates.Moreover, the pressure dust that falls on the separator may also be caused by variations in the thickness of the electrode plate and separator. Therefore, the porosity of the separator corresponding to the local active material surface of the electrode plate is also affected, and the porosity becomes smaller in areas that are subjected to strong pressure, and the electrolyte content varies. This causes variations in the discharge performance of the battery.

Preferably, the separator in contact with both surfaces of the anode plate has sufficient pores uniformly present to allow the electrolyte required for repeated use of discharging and charging the battery to enter.

By the way, in the case of sealed lead-acid batteries, when the battery is charged, oxygen gas generated from the anode plate is absorbed by the cathode active material through a chemical reaction, but if a liquid film exists on the surface of the active material, it is not practical. No such reaction occurs.

It is known that oxygen gas generated from the anode leaves behind a thin film of electrolyte on the surface of the cathode active material and undergoes a chemical reaction with the cathode active material, and this chemical reaction is interpreted to be the main reaction that causes gas absorption to proceed. . However, in the research conducted by the present inventors, the chemical reaction between oxygen gas and the cathode active material that passes through the liquid film is extremely slow motion, only a small amount of reaction occurs, and the main reaction can be the main reaction. This occurs rapidly when a dry, fresh cathode active material encounters and reacts with moderately moist oxygen gas in an atmosphere at a moderate temperature.

In addition, sealed lead-acid batteries have a limited electrolyte and do not have a free electrolyte, so it is necessary to avoid using them in the overcharge region (to suppress hydrogen gas generation), and it is mainly necessary to use a regulated battery with a limited temperature range. A voltage charging method has been adopted. Therefore, unless the temperature and charging conditions are inappropriate, oxygen gas exceeding the oxygen gas absorption capacity of the cathode plate is generated and accumulated, and the internal pressure of the battery increases. In this case, at the same time as the safety valve is activated, gas and, if necessary, water in the electrolytic solution escape to the outside of the battery, resulting in a decrease in the electrolytic solution. Furthermore, the capacity was reduced due to poor sealing between the active material surfaces of the positive and negative electrode plates and the separator made of a fine glass fiber mat. Therefore, in a sealed lead-acid battery, the ability of the cathode plate to absorb oxygen gas becomes a dominant factor in battery life, and there is also the drawback that excellent life performance cannot be obtained.

By the way, in a lead-acid battery with a group of electrode plates immersed in an electrolytic solution, heat generation during charging is mainly caused by a reaction in which oxygen gas and hydrogen gas are generated by electrolysis of water after charging of the electrode plates is completed. However, a sealed lead-acid battery that uses an electrolyte containing dilute sulfuric acid as its main component, and utilizes a mechanism in which oxygen gas generated from the anode plate reacts with the cathode plate during charging, with virtually no free electrolyte. In storage batteries, a large amount of heat is generated when oxygen gas generated from the anode plate reacts with the cathode plate.

This reaction is difficult to occur in a cathode plate that is completely covered with an electrolytic solution, but often occurs in a semi-dry area, so that the temperature rise tends to be large locally on the outer surface of the cathode plate at the end of the electrode plate group. For this reason, there is also a drawback that the synthetic resin plate or synthetic resin battery case that is brought into contact with the electrode plate group may be deformed or damaged during the five-dimensional adjustment.

As described above, in conventional sealed lead-acid batteries, (1) the electrode plate spacing is likely to be uneven. In addition, the amount of electrolyte tends to be insufficient or uneven due to the pressure.

■ Since the oxygen absorption capacity of the cathode plate governs battery life,
It has a short lifespan. In particular, it is difficult to keep the surface of the cathode plate dry.

■ The battery case may become deformed or damaged due to heat generation within the battery.

There are some shortcomings, and it was hoped that they would be resolved.

Among the problems in ■~■, regarding ■, it has been proposed to improve the oxygen absorption capacity of the cathode plate and extend the battery life by providing a specific porous plate on the outside of the cathode plate (Unexamined Japanese Patent Publication No. (Sho 63-155259). However, there is a complaint that the cathode plate area of the non-hole portion of the perforated plate is not utilized.

Regarding (2), it has been proposed that a liquid absorber with a small pore diameter be provided outside the electrode plate group to absorb heat and prevent deformation and damage of the battery case (Japanese Patent Laid-Open No. 63-1521
However, it is difficult to keep the surface of the cathode plate dry using this method.

[Problems to be Solved by the Invention] As described above, a sealed lead-acid battery that can simultaneously solve the above-mentioned problems (1) to (3) has not yet been provided, and an 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) to (3). Namely, the pitch of the electrode plates is constant, it can withstand stress, and it has excellent overcharge life performance. ,
The surface of the cathode plate is kept dry to increase its gas absorption capacity.
Moreover, it is an object of the present invention to provide a high-performance sealed lead-acid battery that does not have the problem of deformation of the battery case due to heat generation.

[Means for Solving the Problems J] The sealed lead-acid battery of the present invention includes alternately arranged anode plates,
The present invention relates to a sealed lead-acid battery in which a separator and a cathode plate are provided in a battery case, and the plates at both ends of a plate group consisting of an anode plate and a cathode plate are used as 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 having built-in ribs made of acid-resistant thermoplastic resin. This solves the problem (2) above.

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

The sheets on both sides of the anode plate are designed to allow the battery to fully demonstrate its potential when discharging at various rates, and are designed to dry out the active material on the outer surface and make it easier to absorb oxygen. It is. The arrangement of thick fibers of 13 to 25 .mu.m is mapara, and the entire area of the cathode plate is used effectively, so the above problem (2) is solved, and since this layer becomes a heat insulating layer, the above problem (2) is also solved.

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

FIG. 1 is a schematic cross-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 includes an anode plate 3 and a cathode plate 4 arranged alternately in a battery case 2, and a separator 5. The plates at both ends of the plate group consisting of the anode plate 3 and the cathode plate 4 (in FIG. 1, the plate group consists of two anode plates 3A, 3B and three cathode plates 4A, 4B, 4C) are as follows. These are cathode plates 4A and 4C. The anode plates 3A and 3B are each mainly composed of glass fibers having a diameter of 2 μm or less, and are covered with separators 5A and 5B each having a built-in rib made of an acid-resistant thermoplastic resin. Further, the outer surfaces of the cathode plates 4A and 4C at both ends of the electrode plate group are, respectively,
It is covered with sheets 6A and 8B made of glass fibers having a diameter of 13 to 25 μm bonded together with an organic binder.

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

The separator 5 shown in FIG. 2 is provided with two ribs 8 in the longitudinal direction (vertical direction in the drawing) in a direction perpendicular to the thickness direction of the separator main body. There is no particular restriction on the number of lines, and the number of lines may be three or four or more.

In normal cases, it is preferable to provide two or three ribs in symmetrical positions, and there is no particular restriction on the direction in which they are arranged.
It is preferable to place the ribs at approximately the center position in the thickness direction of the separator body, in the upright direction of the battery (the length direction of the separator). It can also be provided in Also,
The ribs do not have to be arranged in a straight line, but may be curved as long as they are within the plane of the separator.

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

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

That is, glass fibers or glass fibers 20 mixed with organic fibers as necessary are transferred from a papermaking tank 21 to a papermaking net 22.
As shown in FIG. 3, hot-melt resin 24 flows out from a nozzle 23 in the form of a band at predetermined intervals in the width direction and is fed in parallel to a presser roll 25, as shown in FIG. and embed it in the papermaking mat 26. After papermaking, it is dried using, for example, a drum dryer.

In the present invention, the thickness of the separator is 0.5 to 3.5 m.
m, the thickness of the rib is 50-95% of the thickness of the separator
It is preferable that the volume ratio is about 1 to 5%.

In addition, the acid-resistant thermoplastic resin forming the ribs has a viscosity of 1300 to 10 at a melting temperature of 150 to 200°C.
000 centivoise and a Shore hardness of at least 70 degrees, preferably at least 85 degrees, at room temperature is preferred. Preferred examples of such hot melt resins include:
Examples include mixtures of several types of ethylene vinyl acetate copolymer resin (Toyo Ink "Topco H-01") and attack polypropylene resin.

With hot melt, ribs with the required diameter can be easily created by increasing or decreasing the diameter of the discharge nozzle.

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 made by bonding glass fibers with an average diameter of 13 to 25 μm with an organic binder.

The glass fibers constituting this sheet 6 may be those manufactured by a wet process with an average diameter of 18 .mu.m to 22 .mu.m and a fiber length of 6 to 25 mm, or a dry mat obtained by a felted cotton method. Furthermore, examples of the organic binder that can be used include acrylic binders, cornstarch, and the like. The amount of these organic binders used is
It is preferable that it is 10 to 25% by weight of the weight of a.

Further, in the present invention, this sheet 6 has a density of 0, 1
2-0. It is preferably about 18 g/cm'.

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 electrode plates is five, but in an actual battery, the number of partition plates plus one negative plate is provided.

[Function] In the sealed lead-acid battery of the present invention, since the separator enclosing the anode plate is mainly made of thin glass fiber with an average diameter of 2 μm or less, the liquid absorption rate and liquid holding capacity are high, and the battery performance is improved. It is effective for Furthermore, since the ribs are built-in, the pressure resistance is high, and the thickness of the separator can be kept constant, so the gap between the electrode plates can be kept constant.

In addition, the sheet covering the outer surface of the cathode plates at both ends of the electrode plate group is made by bonding glass fibers with an average diameter of 13 to 25 μm with an organic binder, and has a very low liquid retention rate and a low porosity. Because it is a high sheet, it does not cover the entire outer surface of the cathode plate, and the surface of the cathode plate in contact with this sheet is rarely wet with electrolyte, and is dry in places, so the surface of the #electrode plate is Utilization rate can be increased. Therefore, the oxygen absorption capacity of the cathode plate is improved and the battery life is extended.

Furthermore, thermal deformation of the battery case etc. is also prevented due to the heat insulating effect of this sheet and the electrolyte in the sheet.

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

Example 1 The following materials were used as the anode plate 3, cathode plate 4, separator 5, and sheet 6, and a sealed lead-acid battery (6
VX6A)I) was assembled.

5 pieces / single cell width m43 mm Thickness = 3.4 mm Length m64 mm 4 cathode plates / single cell width m43 mm Thickness = 2.4 mm Length m64 mm Separator width = 53 mm Thickness = 2. 0 mm Length w 144 mm Made of glass fiber with an average diameter of 0.8 μm, as shown in Figure 2, it has two built-in ribs (Toyo Ink Group "Topco H-017J") with a diameter of 1.85 mm.Density 0.1
4g/crn' Sheet width m 53mm Thickness xo, 5mm Length w 62mm Glass mat made of glass fibers with an average diameter of 19μm treated with 15% by weight acrylic resin, density 0.14g/crn
'The obtained sealed lead-acid battery was examined for variations in electrode spacing, overcharge life characteristics, etc., and the results are shown in Table 1, FIG. 4, and FIG. 5.

Comparative Example 1 A sealed lead-acid battery was assembled in the same manner as in Example 1, except that a separator without ribs was used and no sheet was provided. Regarding the obtained sealed lead-acid battery,
The comparison results are shown in Table 1, FIG. 4, and FIG. 5.

Table 1 *1: Difference between maximum interval and minimum interval *2: Sealed reaction efficiency from JIS C8702-1988 commentary This storage battery has a structure that does not allow water replenishment, and the decrease in electrolyte is one of the causes of shortened life. Therefore, it was specified to confirm the reliability of storage batteries.

It is generally believed that the life of this storage battery will end if the water decreases by 2 g/A-h or more per cell due to depletion of the electrolyte. When the sealing reaction efficiency is 90% with a charging current of 0.005 CaA, the time required for a water reduction of 2 g/A-h to occur is *3:5 for a storage battery that has completed the 1 hour rate capacity test specified in BA3018-1987. (1) A fully charged battery is tested at 1.5 mA (0,000 mA) using the following method.
Continuous charging is performed with a constant current of 25C21A).

(2) Discharge at 0.25CaA every 3 months to reach a final voltage of 5
．． Perform a 10V capacity test.

Figures 4 and 5 show the results of an overcharge test conducted for about 60 months at room temperature (in the figure, temperature indicates room temperature).
). When this is calculated according to the Japan Storage Battery Industry Association standard (SBA3018 total overcharge amount (AH) due to overcharge life) (c, Hzo hourly rate capacity), Example 1: 0.00025C3X 24h / day x
3G month/month x 6G month = 1 (over 1.8ca Comparative Example 1: 0.00025C21X 24h/day x 30 month/month x 40 month - 7,2C21) Overcharge life performance has been significantly improved.

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

[Effects of the Invention] As detailed above, according to the sealed lead acid battery of the present invention,
Provided is a sealed lead-acid battery in which the electrode plate spacing is constant, and therefore has excellent battery performance, and has excellent characteristics such as a significantly long overcharge life.

[Brief explanation of drawings]

FIG. 1 is a schematic 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. A schematic side view of a preferred device, FIG. 4 is a diagram showing the overcharge life measurement results of Example 1, and FIG. 5 is a diagram showing the overcharge life measurement results of Comparative Example 1. 1... Sealed lead-acid battery, 2... Battery case, 3...
- Anode plate, 4... Cathode plate, 5... Separator, 6... Sheet. Agent Patent Attorney Tsuyoshi Shigeno Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

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