JPH0883624A - Sealed storage battery - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a sealed storage battery capable of preventing the occurrence of a local oxygen gas absorption reaction by fully adhering pressure spacers to the electrode plates located at both ends of the electrode plate group. . [Structure] An electrode plate group 2 and a pressure spacer 3 for pressing the electrode plate group in the stacking direction are housed in a battery case body 1. The pressure spacer 3 is replaced by a plate member 6 made of polyester resin and having high rigidity.
And a thermally expandable particle layer 7 containing thermally expandable microcapsules having a low boiling point hydrocarbon inside a shell made of a polyvinylidene chloride copolymer, and an elastic body 8 made of butyl rubber. The pressurizing spacer 3, the elastic body 8 is directed to the electrode plate group 2 side, and the thermal expansion particle layer 7 is attached to the battery case body
Place it so that it faces the inner wall surface side of.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealed storage battery, and more particularly to an improvement of a pressure spacer for pressing the electrode plates used in the sealed storage battery in the stacking direction.

[0002]

2. Description of the Related Art Sealed storage batteries such as sealed lead storage batteries are
The retainer is impregnated with the electrolytic solution. Initially, the electrode plate group was inserted into the battery case while being pressed in the stacking direction, and the retainer was pressed against the electrode plate by an appropriate pressing force by the elastic force of the retainer. However, when the electrolyte is injected into the battery case,
The frictional force between the glass fibers forming the retainer decreases, and the elastic force of the retainer decreases. Therefore, sufficient elastic force cannot be obtained only by the elastic force of the retainer. When the applied pressure is reduced, a gap is created between the electrode plate and the retainer, which causes stratification of the electrolytic solution, which lowers the discharge performance or makes the charge / discharge reaction non-uniform, resulting in oxygen gas from the positive electrode plate. The amount of generation increases.

Particularly, in a sealed type storage battery in which negative electrode plates are arranged on both sides of an electrode plate group, if the above-mentioned pressing force is reduced, a thermal runaway state easily occurs. This is because the surfaces of the negative electrode plates located on both sides of the electrode plate on the outer side in the stacking direction of the active material layer do not contribute to the charge / discharge reaction, but contribute significantly to the absorption reaction of the oxygen gas generated from the positive electrode plate. Therefore, the negative electrode plates on both sides of the electrode plate absorb more oxygen gas than the negative electrode plates in the electrode plate group. This absorption reaction becomes more likely to occur as the degree of adhesion between the inner wall surface of the cell chamber and the outer negative electrode plate decreases. When the oxygen gas absorption reaction concentrates on the negative electrode plates at both ends of the electrode plate group, the heat generated by the oxygen gas absorption reaction accelerates the temperature rise of the battery, which causes a heat escape state.

Therefore, in order to solve such a problem,
It has been proposed to arrange a pressure spacer between the inner wall surface in the battery case and the electrode plate group, and positively apply group pressure to the electrode plate group in the stacking direction by the pressure spacer. A pressure spacer of construction has been proposed. When the pressure spacer is used, it is possible to apply group pressure to the electrode plate group without depending on the elastic force of the retainer, so that the active material is softened by the repeated charging and discharging of the storage battery and the expansion and contraction of the active material. In this case, it is possible to prevent the active material from falling off from the current collector, and also to prevent a gap from being formed at the interface between the electrode plate and the retainer, so that the electrolyte solution at the interface between the electrode plate and the retainer can be prevented. Can be prevented from being stratified.

The conventionally proposed pressure spacer includes a sheet-shaped pressure spacer such as a rubber sheet. When this sheet-like pressure spacer is used, a required number of pressure spacers are stacked on the electrode plate group and the pressure spacers are housed in the cell chamber together with the electrode plate group. In addition, by arranging pressure spacers having a spring property bent in an arc shape on both sides of the electrode plate group and accommodating the pressure spacers together with the electrode plate group in the cell chamber, the spring property of the pressure spacers is utilized, Some pressurize the electrode group. Further, there is one in which a convex portion is provided on the inner wall portion of the cell chamber and the convex portion serves as a pressure spacer.

The storage battery proposed by the applicant in Japanese Patent Application No. 5-72024 uses a pressure spacer that is deformed so as to increase the occupied volume in the cell chamber in order to facilitate the assembly of the battery.

[0007]

However, when the sheet-like pressure spacers are used, it is necessary to adjust the number of pressure spacers according to the thickness dimension of the electrode plate group.
There was a problem that the battery assembly work became complicated.
Also, if a pressure spacer that deforms so as to increase the occupied volume in the cell chamber is used, assembly will be easier, but as with other pressure spacers, the electrode plate should be pressed evenly over the entire surface. Was difficult and it was easy to get local pressure. In addition, it is difficult to bring the pressure spacers into close contact with the electrode plates located at both ends of the electrode plate group and to press the electrode plates evenly over the entire surface.

An object of the present invention is to provide a sealed storage battery capable of pressing the electrode plate group with a sufficient force without bias even after the injection of the electrolytic solution.

Another object of the present invention is to provide a sealed storage battery capable of preventing a local oxygen gas absorption reaction from occurring by closely adhering pressure spacers to the electrode plates located at both ends of the electrode plate group. To provide.

[0010]

According to the present invention, an electrode plate group and a pressure spacer for pressing the electrode plate group in the stacking direction are housed in a cell chamber, and the pressure spacer increases an occupied volume in the cell chamber. A sealed storage battery that deforms like this is targeted for improvement.

In the present invention, the pressure spacer is a plate body having high rigidity, and a heat-expandable particle layer containing heat-expandable particles which is arranged on one surface side of the plate member and expands when heated. It is configured by a three-layer structure with an elastic body arranged on the other surface side of the plate-shaped body. Then, the pressure spacer is arranged in the cell chamber so that the elastic body faces the electrode plate group side and the heat-expandable particle layer faces the inner wall surface side of the cell chamber.

Here, the highly rigid plate-like body is formed of a material having resistance to an electrolytic solution, and is largely deformed at a temperature at which the thermally expandable particles in the thermally expandable particle layer are expanded. It is formed of a material that has heat resistance and rigidity to such an extent that it does not deform and is not easily deformed by the force generated by the expansion of the thermally expandable particle layer. In the case of a lead storage battery, this plate-shaped body can be made of an acid-resistant plastic such as polyester or epoxy resin. Since the plastic is easy to mold and the price is low, the plate-shaped body can be manufactured at low cost.

The thickness of the plate-shaped body varies depending on the material of the plate-shaped body, but it may be determined so that the required rigidity is obtained and the plate-shaped body does not become too thick. It is preferable that the plate body having high rigidity has a size capable of covering substantially the entire side surface (active material surface) of the electrode plate. This is because if the size of the plate-shaped body becomes too small, the electrode plate group will be locally pressed.

As the heat-expandable particles, those having electrolytic solution resistance and capable of largely expanding at a relatively low temperature (large expansion coefficient) can be used. For example, thermally expandable microcapsules can be used as the thermally expandable particles. Here, the thermally expandable microcapsule has a structure in which a thermally expandable material (such as a low boiling point gas) is enclosed in a microcapsule, that is, a shell formed of a material that can expand when heated. The material of the microcapsules or shells may be any material as long as it is resistant to the electrolytic solution and has strength sufficient to maintain its shape after expansion. The thermal expansion material to be contained in the capsule may be any material as long as it does not adversely affect the properties of the electrolytic solution even if it comes out of the microcapsule. As such a thermal expansion type microcapsule, one having a shell made of a vinylidene chloride copolymer containing a low boiling point hydrocarbon inside can be easily obtained. As the heat-expandable particles, the particle diameter before expansion which is generally commercially available is 10 to 10.
Thermally expandable microcapsules in the range of 30 μm can be used. This type of heat-expandable microcapsule expands 20 to 80 times in size due to heat. The amount of the heat-expandable particles in the heat-expandable particle layer is preferably in the range of 25 to 75% by weight based on the total weight of the heat-expandable particle layer. When the amount of the heat-expandable particles is less than 25% by weight, there is a problem that the electrode plate group cannot be pressed with sufficient force without any bias, and when the amount of the heat-expandable particles is more than 75% by weight. This is because the problem that the heat-expandable particles fall off from the heat-expandable particle layer or the heat-expandable particle layer peels off from the plate-shaped body occurs.

The heat-expandable particle layer must have a structure that allows expansion of the heat-expandable particles but prevents movement of the heat-expandable particles. It is necessary that the heat-expandable particles are entirely dispersed and arranged therein. The heat-expandable particle layer satisfying such requirements can be easily formed, for example, by applying a slurry containing heat-expandable particles (heat-expandable microcapsules, etc.) to one surface of a plate-like body and drying it. You can A thickener and an appropriate binder are added to the slurry.

The elastic body is easily deformed by an external force,
It is formed of a material that is resistant to the electrolytic solution, has a high-temperature use limit temperature higher than the expansion temperature of the heat-expandable particles, and is capable of intimate contact along the unevenness of the surface of the electrode plate. As such a material, rubber such as butyl rubber, ethylene propylene rubber, chlorosulfonated polyethylene rubber, and fluororubber is preferable. In particular, butyl rubber has a high acid resistance, a high elongation rate, a high temperature use limit temperature of 140 ° C. or higher, and is suitable for a sealed lead acid battery.

The pressure spacers may be arranged on both sides of the electrode plate group, but the pressure spacers may be arranged on only one side of the electrode plate group. When the negative electrode plates are arranged on both sides of the electrode plate group, it is preferable to arrange the pressure spacers on both sides of the electrode plate group.

[0018]

In the pressure spacer used in the present invention, the elastic body is arranged on the side of the electrode plate group with the plate body having high rigidity interposed therebetween. When the plate body having high rigidity is provided, the force of the expanding heat-expandable particle layer is dispersed in the entire plate body, and the elastic body can be uniformly pressed by the whole plate body. Moreover, by using the elastic body, it is possible to eliminate the settling with time. Moreover, in the present invention, the heat-expandable particle layer containing the heat-expandable particles that expands when heated is expanded to generate a pressing force. The thermally expandable particles are sensitive to temperature and expand in proportion to temperature. Moreover, a predetermined temperature (for example, 60 to 80 ° C.)
The volume of change is large as the fourth power of the radius because it has a spherical shape in addition to having a characteristic of rapidly expanding at a certain degree). Therefore, the heat-expandable particle layer formed by collecting the heat-expandable particles (heat-expandable microcapsules and the like) efficiently expands heat, as compared with the case of using a plate-shaped heat-expandable material.

Further, in the present invention, the elastic body disposed in the portion of the electrode plate group that comes into contact with the outermost electrode plate is in close contact with the outer surface of the electrode plate in the stacking direction, and the surface and the surrounding atmosphere. Cut off contact. In particular, when the electrode plate is a negative electrode plate, it is possible to suppress contact between the oxygen gas generated during the charging reaction and the surface of the electrode plate on the outer side in the stacking direction. Can be prevented.

Therefore, according to the present invention, since the electrode plate group can be pressed with a sufficient force without being biased as a whole, a gap is prevented from being formed at the interface between the electrode plate and the retainer, and It is possible to effectively prevent stratification of the electrolytic solution at the interface with the retainer. As a result, according to the present invention, the charge / discharge reaction, that is, the ion movement between the positive and negative electrode plates is smoothly performed, and the discharge performance is improved. In addition, heat escape can be prevented.
Further, even if the pressing force at the time of assembly is small, a high pressing force can be obtained by the expansion after the assembly, and the workability of the assembly can be improved.

Particularly when heat-expandable microcapsules are used as the heat-expandable particles, a necessary and sufficient pressure can be obtained. Particularly, when the thermal expansion type microcapsule is constituted by including a low boiling point hydrocarbon in the inside of the microcapsule made of a vinylidene chloride copolymer, 100 ° C to 130 ° C.
By heating at 0 ° C for 1 minute, the volume after heating becomes 20 to 80 times the volume before heating. This is because the low-boiling point hydrocarbon inside expands by heating and the thermal expansion type microcapsule expands. When the thermally expanded microcapsule expands to a certain extent, the low boiling point hydrocarbons escape to the outside of the microcapsule through the shell wall made of vinylidene chloride copolymer. Since the low boiling point hydrocarbon has a relatively high volume expansion coefficient, according to the present invention, the thermal expansion type microcapsule can be largely expanded at a low heating temperature.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a schematic cross-sectional view of an embodiment in which the present invention is applied to a 2V-24Ah sealed lead acid battery. In FIG. 1, 1 is a battery case main body, 2 is an electrode plate group, and 3 is a pressure spacer. The battery case body 1 is made of synthetic resin. The electrode plate group 2 includes three positive electrode plates 2a having dimensions of 115 mm × 135 mm × 3 mm and 115 mm × 135 mm × 2.
mm four negative electrode plates 2b ... and 119 mm × 140 mm × 2 mm
Of the positive electrode plate 2a and the negative electrode plate 2b are connected to each other by straps and are provided on the lid of the battery case body 1. The positive and negative terminals 5 are electrically connected to each other.

The pressure spacer 3 has a flat plate shape as a whole, and is placed in the cell chamber 1 in a state of being superposed on the electrode plate group 2.
It is stored in a. The pressure spacer 3 has a three-layer structure including a rigid body having a high rigidity, that is, a plate-like body 6, a heat-expandable particle layer 7 containing heat-expandable particles that expand when heated, and an elastic body 8.

The plate-like body 6 of this embodiment is made of acid-resistant plastic, and specifically, has a thickness of 120 mm × 140.
It is composed of mm x 2 mm polyester resin plate.
One surface of the plate-shaped body 6 is blown with chlorine (Cl) gas at a predetermined temperature (40 to 100 ° C.) for a predetermined time (30 to 12).
0 minute) A Cl treatment for reacting is applied. When Cl treatment is applied, the wettability (hydrophilicity) of the polyester becomes high, and it becomes easy to apply the slurry or the like.

The heat-expandable particle layer 7 is formed by applying a slurry containing heat-expandable microcapsules to the Cl-treated surface of the plate 6 and then drying it. The amount of slurry applied was such that the thickness after drying was 2 mm. In this example, as the heat-expandable microcapsules,
A shell (microcapsule) made of vinylidene chloride resin containing a low boiling point hydrocarbon is used. In this example, the thermally expandable microcapsules sold by Matsumoto Yushi-Seiyaku Co., Ltd. under the product name Matsumoto Microsphere series had a particle size of 10 to 30 before expansion.
The thing with a micrometer was used. The content of the heat-expandable microcapsules may be appropriately determined according to the required expansion amount. In this example, the heat-expandable microcapsules, hydroxypropyl cellulose as a thickener, and water were mixed at a ratio of 1:
The heat-expandable particle layer 7 is formed by using a slurry prepared by mixing in a ratio of 1: 8. The heat-expandable microcapsules, the thickener and water can be mixed in an acceptable mixing ratio of 0.5: 1: 9.5 to 2: 1: 7.

As the elastic body 8 arranged on the other surface of the plate-like body 6, an elastic body made of butyl rubber having a size of 120 mm × 140 mm × 2 mm is used.
Bonded to the untreated surface of. The plate-like body, the heat-expandable particle layer and the elastic body each preferably have a thickness of 1 to 3 mm.

The electrolytic solution poured into the battery case body 1 has a specific gravity of 1.
It was diluted sulfuric acid of 320 (20 ° C.), and 180 ml of this electrolytic solution was injected into the battery case body 1 to obtain a sealed lead acid battery with a discharge capacity of 24 Ah (20 hour rate). After injecting the electrolyte,
The heat-expandable microcapsules were expanded by heating at 80 ° C. for 5 minutes using a thermostat. In the battery thus manufactured, the force for pressing the electrode plate group 2 in the stacking direction is about 40 kg / dm ²
Met.

Next, the results of testing the charging performance of the battery of this example will be described. The test was carried out using a battery (invention product) having the structure of FIG.
The same battery (conventional product) as the conventional battery having no pressure spacer, which is made by arranging mm × 140 mm × 6 mm polyester plates at both ends in the laminating direction of the electrode plate group, was performed.

The test for cycle life characteristics was carried out by using a plurality of batteries of the present invention and a plurality of conventional batteries.
The charging / discharging cycle of carrying out discharge for 2 hours at 0.25 CA and charging for 6 hours at 0.1 CA is repeated, discharging every 25 cycles until the voltage becomes 1.7 V at 0.25 CA, and the respective capacities at that time are discharged. It was measured. FIG. 2 shows the test results. The reason why the test results are band-shaped is that the range of the maximum value and the minimum value of the measurement results of the plurality of batteries used in the test is illustrated. In this test, the initial capacity of each battery is set to 100%, and when the capacity becomes smaller than 50%, it is determined that the life has been reached. From the results of this test, the battery of the present invention has almost twice as long life as the battery of the conventional product. This is because, in the battery of the present invention, the electrode plate group is constantly pressed by the pressure spacer, so that the active material is prevented from falling off and the lattice body used for the current collector is prevented from extending.

FIG. 3 shows the test results of the heat escape test. The thermal escape test was to measure the ratio between the ambient temperature of the battery and the floating charge current (the value of the floating charge current when the ambient temperature was 25 ° C. was 1). The floating charging condition was set at a set voltage of 2.275 V / cell. As can be seen from this result, the ambient temperature of the conventional battery is 40 ° C.
Before it became, the floating charge current ratio increased significantly,
I've run into a heat escape. On the other hand, in the battery of the present invention, the floating charging current ratio did not exceed 10 times even when the ambient temperature reached 70 ° C. That is, it was confirmed that the battery of the present invention did not lead to heat escape. Further, it can be seen that the battery of the present invention can reduce the floating charging current as compared with the battery of the conventional product.

In the above examples, the heat-expandable microcapsules containing the low boiling point gas inside were used as the heat expandable particles, but only the heat expandable resin such as vinylidene chloride copolymer containing no low boiling point gas inside. Needless to say, the heat-expandable particles consisting of may be used.

Although the above embodiment applies the present invention to a sealed lead acid battery, it goes without saying that the present invention can also apply other types of sealed lead acid batteries.

The constituent features of some of the inventions described in the specification of the present application will be described below.

(1) An electrode plate group and a pressure spacer for pressing the electrode plate group in the stacking direction are housed in a cell chamber, and the pressure spacer deforms so as to increase the occupied volume in the cell chamber. A lead-acid battery, wherein the pressure spacer has a plate-like body made of plastic having high rigidity and acid resistance, and an acid-proof that is arranged on one surface side of the plate-like body and expands when heated. Comprising a heat-expandable microcapsule having a heat-expandable microcapsule and a rubber elastic body having acid resistance disposed on the other surface side of the plate-like body. Is arranged in the cell chamber so that the elastic body faces the electrode plate group side and the heat-expandable particle layer faces the inner wall surface side of the cell chamber.

(2) The sealed lead-acid battery according to (1), wherein the plate-shaped body is made of polyester or epoxy resin.

(3) The heat-expandable particle layer is formed in such a manner that a slurry containing heat-expandable microcapsules is applied and dried on one surface of the plate-like body to form a closed type. Lead acid battery.

(4) The slurry contains the heat-expandable microcapsules, the thickener, and water in a ratio of 0.5: 1: 9.5-2: 5.
The sealed lead-acid battery according to (3), which is made by mixing in a range of 1: 7.

(5) The plate-like body has a thickness of 1 to 3 mm, and the heat-expandable particle layer has a thickness of 1 to 3 mm. .

(6) The heat-expandable microcapsules are
The sealed lead-acid battery according to (5) above, which has an average particle diameter of 10 to 30 μm.

(7) An electrode plate group and a pressure spacer for pressing the electrode plate group in the stacking direction are housed in a cell chamber, and the pressure spacer is deformed so as to increase the occupied volume in the cell chamber. A lead-acid battery, wherein the pressure spacer comprises a plate having high rigidity made of a plastic having acid resistance, and a vinylidene chloride copolymer shell disposed on one surface side of the plate. Consisting of a heat-expandable particle layer containing heat-expandable microcapsules containing low-boiling hydrocarbons, and a rubber elastic body arranged on the other surface side of the plate-like body. , The thickness of the plate is 1-3 mm
The thickness of the thermally expandable particle layer is 1 to 3 mm, the thickness of the elastic body is 1 to 3 mm, the average particle diameter of the thermally expandable microcapsules is 10 to 30 μm, and the thermally expandable particle layer is 25 to 75% by weight of the total weight of the pressure chamber, and the pressure spacer directs the elastic body toward the electrode plate group and the heat-expandable particle layer toward the inner wall surface of the cell chamber. A sealed lead-acid battery, characterized in that it is arranged in the cell chamber.

(8) An electrode plate group having negative electrode plates at both ends in the stacking direction and a pressure spacer for pressing the electrode plate group in the stacking direction are housed in the cell chamber, and the pressure spacer is occupied in the cell chamber. A sealed storage battery that deforms so as to increase in volume, wherein the pressure spacer is a plate body having high rigidity, and thermal expansion that is arranged on one surface side of the plate body and expands when heated. Having a three-layer structure of a heat-expandable particle layer containing conductive particles and an elastic body arranged on the other surface side of the plate-like body, wherein the pressure spacer includes the elastic body as the negative electrode of the electrode plate group. The sealed storage battery is arranged in the cell chamber so as to face the plate side and the heat-expandable particle layer toward the inner wall surface side of the cell chamber.

[0042]

According to the present invention, the electrode plate group can be pressed with a sufficient force without being biased as a whole, so that a gap can be prevented from being formed at the interface between the electrode plate and the retainer, and the electrode plate can be prevented. It is possible to effectively prevent stratification of the electrolytic solution at the interface between the retainer and the retainer. As a result, according to the present invention, the charge / discharge reaction, that is, the ion movement between the positive and negative electrode plates is smoothly performed, and the discharge performance is improved. In addition, heat escape can be prevented.

Especially when heat-expandable microcapsules are used as the heat-expandable particles, a necessary and sufficient pressure can be easily obtained.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of an embodiment in which the present invention is applied to a sealed lead-acid battery.

FIG. 2 is a diagram showing the results of measuring cycle life characteristics of a battery of the present invention and a battery of a conventional product.

FIG. 3 is a diagram showing the results of measuring the relationship between the ambient temperature and the floating charging current ratio of the battery of the present invention and the battery of the conventional product.

[Explanation of reference symbols] 1 battery case body 2 electrode plate group 2a positive electrode plate 2b negative electrode plate 3 pressure spacer 4 separator 6 plate-like body 7 heat-expandable particle layer 8 elastic body

Claims (4)

[Claims] 1. A hermetically sealed type in which an electrode plate group and a pressure spacer for pressing the electrode plate group in a stacking direction are housed in a cell chamber, and the pressure spacer deforms so as to increase an occupied volume in the cell chamber. In the storage battery, the pressure spacer includes a plate body having high rigidity, and a heat-expandable particle layer including heat-expandable particles that is arranged on one surface side of the plate body and expands when heated. , A three-layer structure with an elastic body arranged on the other surface side of the plate-like body, wherein the pressure spacer directs the elastic body to the electrode plate group side and the thermal expansion particle layer to the cell. A sealed storage battery, which is arranged in the cell chamber so as to face the inner wall surface of the chamber. 2. The heat-expandable particles are composed of heat-expandable microcapsules having a low boiling point gas inside, and the heat-expandable particles are arranged so as to be totally dispersed in the heat-expandable layer. The sealed storage battery according to item 1. 3. The sealed storage battery according to claim 2, wherein the thermally expandable microcapsules are configured such that a shell made of vinylidene chloride copolymer contains a low boiling point hydrocarbon. 4. The sealed storage battery according to claim 1, wherein the elastic body is made of rubber having electrolytic solution resistance.