JP2822701B2 - Sealed alkaline storage battery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealed alkaline storage battery, and more particularly, to a sealed alkaline storage battery excellent in internal pressure characteristics and life characteristics.

[0002]

2. Description of the Related Art Normally, a sealed alkaline storage battery comprises a positive electrode plate, a negative electrode plate, a separator, an electrolyte, a case, and a sealing plate, and a non-woven fabric formed of a polyamide resin, a polypropylene resin or the like is generally used as the separator. Have been.

In order to respond to the demand for higher capacity batteries in recent years as electronic devices become smaller and lighter, the thickness of the case is reduced to increase the internal volume, or the thickness of the separator that does not contribute to the capacity is reduced. Then, the internal volume is increased thereby to cope with the problem.

However, when the separator is made thinner, the liquid retention of the electrolytic solution is deteriorated, and when charging and discharging are repeated, there arises a problem that the life of the separator is deteriorated due to the withdrawal of the liquid. This problem,
This can be solved by increasing the electrolyte,
When the amount of the electrolyte is increased, the internal pressure of the battery is increased, and the liquid is likely to leak. Further, when the thickness of the separator is small, there is a problem that a short circuit occurs between the positive electrode and the negative electrode due to dendrite generated by long-term use, self-discharge increases, and the life tends to deteriorate.

Therefore, in order to solve such a problem, Japanese Patent Application Laid-Open No. 1-157055 has proposed that the porosity of the surface layer portion of the separator be different from that of the inside of the separator. It has been proposed to make the shape of the internal hole of the separator circular or elliptical.

[0006]

However, when the porosity of the surface layer of the separator is different from that of the inside as in Japanese Patent Application Laid-Open No. 1-157055, it is necessary to stably reduce the porosity of the surface layer. However, as a result, there is a problem that gas permeability is not stable. Further, when the shape of the internal hole of the separator is circular or the like as in Japanese Patent Application Laid-Open No. 1-264167, the problem that the liquid retention property is poor and the life of the separator is degraded due to liquid withdrawal occurs again. Would.

Accordingly, an object of the present invention is to provide a sealed alkaline storage battery having excellent internal pressure characteristics and life characteristics.

[0008]

Means for Solving the Problems As a result of intensive studies, the inventors have found that the maximum amount of electrolyte that can be exploited by repeated charging and discharging of the separator is 35 g / m ² , and the separator is drained up to 0 V due to the withdrawal of the separator. Since the minimum amount of electrolyte required for a non-discharge is 25 g / m ² , it has been found that the above problem can be solved if the amount of electrolyte retained in the separator at the time of complete discharge is at least 60 g / m ² .

[0009] The present invention is based on this finding,
In a sealed alkaline storage battery including a positive electrode plate, a negative electrode plate, a separator, an electrolyte, a case, and a sealing plate, the electrolyte retention amount of the separator at the time of complete discharge is 60 g / m ^2. .

It is desirable that the distribution of the electrolyte in the separator at the time of complete discharge is 25% by weight or more. The electrolyte retention rate of the separator is 300% or more by weight, preferably 350% or more, and the electrolyte absorption rate is 20 mm / 30.
min or more, preferably 25 mm / 30 min. The electrolyte retention rate was measured by immersing in a 30% by weight potassium hydroxide solution for 30 minutes. The electrolyte absorption rate was determined from the height when immersed in a potassium hydroxide solution having a concentration of 30% by weight. Further, the separator has a thickness of 140
It is formed of a non-woven fabric having a weight of 60 to 70 g / m ² and an average fiber diameter of the constituent fibers of the non-woven fabric of 3 to 9 μm. The reason why the average fiber diameter is desirably in the range of 3 to 9 μm is that this range is preferable from the viewpoints of the liquid retaining property and the tensile strength required for forming the group. The thickness was measured with a dial thickness gauge (measuring force 1.4 N). The separator that can be used in the present invention can be manufactured by a usual method for manufacturing a nonwoven fabric, but is preferably manufactured by a melt blow method that can make the orientation of fibers random to improve the liquid retention rate. The separator is made of a polyamide resin such as 6-nylon, 6,6-nylon or 4,6-nylon or an olefin resin such as a polypropylene resin or a polyethylene resin using fuming sulfuric acid. It is desirable to use a resin which has been subjected to a treatment to impart hydrophilicity, and among these, a polyamide resin is particularly preferred because it has excellent liquid retention properties.

[0011]

In the present invention, since the amount of electrolyte retained in the separator at the time of complete discharge is 60 g / m ² or more,
It is not necessary to increase the electrolytic solution, and a sealed alkaline storage battery having excellent internal pressure characteristics can be obtained. In addition, since the electrolyte retention rate is good, the separator is hardly withered, and the life characteristics are excellent. Further, by using fine fibers as constituent fibers of the separator, the dendrite resistance can be improved.

In particular, when a positive electrode plate is used in which a foamed metal is used as a substrate and an active material containing nickel hydroxide as a main component is used , the separator is pressed by the pressure caused by the expansion of the positive electrode plate.
This is effective because the liquid tends to wither due to pressurization .

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail, but the present invention is not limited to these embodiments.

Example 1 The average effective fiber diameter was 6.2 μm, the basis weight was 60 g / m ² ,
6-Nylon separator with random fiber orientation with specifications of thickness 220μm, electrolyte retention rate 375%, electrolyte absorption rate 25mm / 30min , core material made of nickel foam metal and nickel hydroxide as main component Filling active material
A positive electrode plate, a nickel-plated punched metal, and a paste-type cadmium negative electrode plate in which an active material containing cadmium oxide as a main component was applied were formed into a group and inserted into a cylindrical case. Next, a potassium hydroxide solution having a concentration of 15% by weight was injected as an electrolytic solution to produce a sealed alkaline storage battery having a nominal capacity of 1200 mAh and a size of 4 / 5A.

A gas pressure gauge was attached to the battery, and a charge / discharge cycle of charging at 1200 mA for 2 hours and discharging at a constant resistance of 1Ω until the discharge voltage reached 1.0 V was repeated 5 times in an atmosphere of 0 ° C. The gas pressure in the battery at the fifth cycle at that time was measured. The results are shown in (Table 1).

[0016]

[Table 1]

Further, the battery was discharged to 1200 V at 1200 mA, and further connected to a constant resistance of 1 Ω to discharge to 0 V, thereby obtaining a completely discharged state. The sealed alkaline storage battery was disassembled, and the electrolyte distribution of the positive electrode plate, the negative electrode plate, and the separator was determined. The results are shown in (Table 1). As is clear from (Table 1), the electrolyte retention amount of the separator was 76 g / m ² ,
The electrolyte distribution of each of the positive electrode plate, the negative electrode plate, and the separator was 38%, 32%, and 30% by weight, and the gas pressure in the battery was 2.5 kg / m ² .

Next, charge at 1200 mA for 1.5 hours,
A cycle life test consisting of 1.25 hours of discharge and 0.25 hours of rest was performed so that the battery was completely discharged at 200 mA until the discharge end voltage reached 0 V. The result is shown in FIG. As is clear from FIG. 1, even after 1000 cycles, the capacity is 82% of the capacity before the test.
That is, the capacity retention was excellent .

Example 2 The average effective fiber diameter was 5.1 μm, the basis weight was 70 g / m ² ,
Using a 6,6-nylon separator having a thickness of 175 μm, an electrolyte retention rate of 360%, and an electrolyte absorption rate of 22 mm / 30 min and random fiber orientation , the same positive electrode plate and negative electrode plate as in Example 1, In the same manner as in Example 1, the concentration was 2
A 0 wt% potassium hydroxide solution was injected as an electrolytic solution to produce an AA size sealed alkaline storage battery with a nominal capacity of 800 mAh.

A gas pressure gauge was attached to the battery, and a charge / discharge cycle of 800 mA-2 hours and a charge / discharge cycle until the discharge voltage reached 1.0 V with a constant resistance of 1.5Ω was repeated 5 times in an atmosphere of 0 ° C. The gas pressure in the battery at the fifth cycle at that time was measured. The results are shown in (Table 1).

Further, the battery is discharged to 1.0 V at 800 mA,
Further, the battery was discharged for 1 hour by connecting a constant resistance of 1.5 Ω to a complete discharge state in which the battery was discharged to 0V. The sealed alkaline storage battery was disassembled, and the electrolyte distribution of the positive electrode plate, the negative electrode plate, and the separator was determined. The results are shown in (Table 1). (Table 1)
As is clear from FIG.
g / m ² , the electrolyte distribution of each of the positive electrode plate, the negative electrode plate, and the separator was 38%, 35%, and 27% by weight, and the gas pressure in the battery was 3.6 kg / m ² .

Next, the battery was charged at 800 mA for 1.5 hours,
A cycle life test consisting of 1.25 hours of discharge and 0.25 hours of rest was conducted so that the discharge end voltage was 0 V at 0 mA to achieve a complete discharge state. The result is shown in FIG. As is clear from FIG. 1, even after 1000 cycles , the capacity retention was excellent at 75% of the capacity before the test.

Example 3 The average effective fiber diameter was 4.5 μm, the basis weight was 70 g / m ² ,
A 6,6-nylon separator with a fiber orientation of 155 μm, an electrolyte retention rate of 391%, and an electrolyte absorption rate of 26 mm / 30 min with random fiber orientation , a sintered positive electrode plate, and the same negative electrode plate as in Example 1. In the same manner as in Example 1, a 4 / 5A sealed alkaline storage battery having a nominal capacity of 1200 mAh and a potassium hydroxide solution having a concentration of 15% by weight as an electrolytic solution was produced.

Using this sealed alkaline storage battery, the gas pressure in the battery and the electrolyte solution distribution of the separator were determined in the same manner as in Example 1. The results are shown in (Table 1). (Table 1)
As is clear from FIG.
g / m ² , the electrolyte distribution of each of the positive electrode plate, the negative electrode plate, and the separator was 32%, 30%, and 38% by weight, and the gas pressure in the battery was 2.9 kg / m ² .

Next, the same cycle life test as in Example 1 was performed. The result is shown in FIG. As is clear from FIG. 1, even after 1000 cycles, the capacity was 85% of the capacity before the test , and the capacity retention was excellent.

Comparative Example 1 As Comparative Example 1, instead of the separator of Example 1, the average effective fiber diameter was 18.6 μm, the basis weight was 75 g / m ² ,
A 6-nylon separator having a thickness of 220 μm, an electrolyte retention rate of 236%, an electrolyte absorption rate of 16 mm / 30 min, and a uniform fiber orientation , the positive electrode plate used in Example 1,
Using a negative electrode plate, a sealed alkaline storage battery having a nominal capacity of 1200 mAh and a size of 4/5 A was manufactured in the same manner as in Example 1.

Using this sealed alkaline storage battery, the gas pressure in the battery and the electrolytic solution distribution of the separator were determined in the same manner as in Example 1. The results are shown in (Table 1). As is clear from (Table 1), the electrolyte retention amount of the separator is 45 g / m ² , and the respective electrolyte distributions of the positive electrode plate, the negative electrode plate, and the separator are 41%, 39%, and 20% by weight. The gas pressure in the battery was 6.4 kg / m ² . Next, the same cycle life test as in Example 1 was performed. The result is shown in FIG. As is clear from FIG. 1, after 320 cycles, the capacity was reduced to 50% or less of the initial capacity, and the life of the separator was deteriorated due to the withdrawal of the liquid.

Comparative Example 2 As Comparative Example 2, instead of the separator of Example 3, the average effective fiber diameter was 23.3 μm and the basis weight was 80 mm / 30.
Using a 6,6-nylon separator having specifications of min. and having a uniform fiber orientation , the positive electrode plate and the negative electrode plate used in Example 3, in the same manner as in Example 3, a nominal capacity of 1200 mAh
The sealed alkaline storage battery of size 4 / 5A was produced.

Using this sealed alkaline storage battery, the gas pressure in the battery and the distribution of the electrolyte in the separator were determined in the same manner as in Example 3. The results are shown in (Table 1). As is clear from (Table 1), the electrolyte retention amount of the separator is 55 g / m ² , and the respective electrolyte distributions of the positive electrode plate, the negative electrode plate, and the separator are 39%, 39%, and 22% by weight ratio. The gas pressure inside the battery was 5.4 kg / m ² . Next, the same cycle life test as in Example 3 was performed. The result is shown in FIG. As is clear from FIG. 1, after 460 cycles, the capacity was reduced to 50% or less of the initial capacity, and the life of the separator was deteriorated due to the withdrawal of the liquid.

[0030]

As is apparent from the above description, in the sealed alkaline storage battery of the present invention, the amount of electrolyte retained in the separator at the time of complete discharge is 60 g / m ² or more. A sealed alkaline storage battery having excellent internal pressure characteristics can be obtained. In addition, port
Uses lamide fiber and the fiber orientation is random
As a result, the electrolyte retention rate is good, so that the separator is less likely to wither and the life characteristics are excellent. Further, by using fine fibers as the constituent fibers of the separator, the dendrite resistance can be improved.

In particular, when a positive electrode plate made of foam metal as a core material and filled with an active material mainly composed of nickel hydroxide is used, the separator dies due to expansion of the positive electrode plate.
Is easy to occur, so that it is effective in suppressing this liquid withering .

[Brief description of the drawings]

FIG. 1 is a characteristic diagram showing the relationship between the number of charge / discharge cycles and the capacity retention of a sealed alkaline storage battery according to an embodiment of the present invention and a sealed alkaline storage battery according to a comparative example.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hideo Kaiya 1006 Kazuma Kadoma, Kadoma City, Osaka Inside Matsushita Electric Industrial Co., Ltd. (56) References JP-A-63-81763 (JP, A) (58) Survey Field (Int.Cl. ⁶ , DB name) H01M 2/16 H01M 10/34

Claims (3)

(57) [Claims] 1. A sealed alkaline storage battery comprising a positive electrode plate, a negative electrode plate, a separator, an electrolyte, a case, and a sealing plate,
The separator is made of a single polyamide fiber having a random fiber orientation, and is used for separating the electrolyte solution in the battery system.
The electrolyte retention ratio of the
The electrolyte retention volume of the separator during the complete discharge is 60
g / m ² or more . 2. The separator has an electrolyte retention rate of 30% by weight.
2. The sealed alkaline storage battery according to claim 1, wherein the electrolyte absorption rate is 0 mm or more and the electrolyte absorption rate is 20 mm / 30 min or more. 3. The separator according to claim 1, wherein said separator has a thickness of 140 to 250 μm.
m, a basis weight of 60 to 70 g / m ² , and an average fiber diameter of constituent fibers of the nonwoven fabric is 3 to 9 μm.
The sealed alkaline storage battery according to claim 1, wherein: