JP2001273909A - Alkaline battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem of degradation of anti-leakage property in a sealing part at an opening end of a positive electrode case because of pressure by volumetric swelling of a negative electrode mixture in an increase of a battery capacity. SOLUTION: The positive electrode mixture 2 and the negative electrode mixture 4 are filled up and separated from each other physically by way of a separator 3 in a bottomed cylindrical positive electrode case 1, and the separator 3 forms a tube swelling part 3c to swell into the cylindrical space of the separator 3 at the bottom surface 3b of a bottomed cylindrical shape. By this tube swelling part 3c, in case the abnormal cubical expansion occurs, the tube swelling part 3 reversely carves out onto the bottom side of the case 1, creates an escape of cubical expansion and effectively prevents liquid leakage from being produced at the sealing part on the opening end side of the case 1 on the opposite side of this bottom surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alkaline battery, and more particularly to an improvement in leakage resistance of a sealing portion.

[0002]

2. Description of the Related Art In recent years, with the development of portable electronic equipment, a large current can be taken out as a power supply battery thereof.
There is an increasing demand for high capacity batteries that can be used for a longer time. In a conventional alkaline battery, for example, as shown in FIG. 3, a cylindrical positive electrode mixture 102 is inserted into a bottomed cylindrical positive electrode case 101 in electrical connection with the inner wall surface of the cylindrical portion of the positive electrode case. Then, a bottomed cylindrical separator 103 is disposed therein, and the separator 103 is physically separated from the positive electrode mixture 102 and filled with the negative electrode mixture 104. A negative electrode current collector pin 105 is inserted into the center of the negative electrode mixture material 104, and its head is connected to the positive electrode case 10.
1 is connected to the negative electrode terminal plate 106 provided at the sealing portion at the opening end.

The bottomed cylindrical separator 103 is formed by, for example, bending a strip-shaped pair of separator pieces into a U-shape by pressing, for example, and bending them into a cylindrical surface, and rotating each other by 90 °. It is configured in a cylindrical shape with a bottom as a whole when overlapped with the state. The bottom surface 103b of the cylindrical separator 103 having a bottom is formed with each separator piece 103A.
The bottom surface 103b is formed as a flat surface.

In order to construct a large-capacity battery that can be used for a long time in the battery having the above-described structure, the case 101 and the separator 103 are made thinner or the positive electrode The high-density filling of the composite material 102 and the negative electrode composite material 104 or the positive electrode case 10
The size of the sealing portion at the opening end of the device 1 is reduced.

[0005] However, the internal capacity of the battery is limited, and generally, there is an incompatible relationship between high capacity and safety. When the capacity is increased, safety is reduced. For example, in the discharge of a battery using a manganese dioxide-based active material for the positive electrode, a zinc-based active material for the negative electrode, and potassium hydroxide or sodium hydroxide as an electrolyte, the positive electrode of the positive electrode mixture is used. Manganese dioxide as an active material is reduced to manganese oxyhydroxide, and zinc as a negative electrode active material of the negative electrode mixture is oxidized to zinc oxide, but volume expansion occurs with this reaction. Therefore, when the positive electrode mixture 102 and the negative electrode mixture 104 are packed at a high density as described above, the volume expansion will be larger. And, further, when proceeding to the overdischarge region, this volume expansion becomes more remarkable.

[0006]

However, since the above-mentioned volume expansion mainly expands toward the opening side, especially when the battery capacity is to be increased as described above, the above-described conventional structure requires the positive electrode. It has been found that a large push-up occurs due to an increase in pressure due to the volume expansion on the sealing side of the case 101, and a problem arises with respect to liquid leakage resistance in the sealing portion at the opening end of the positive electrode case 101.

In the present invention, there is provided an alkaline battery capable of effectively solving the problem of liquid leakage resistance even when the capacity of the negative electrode mixture is increased due to the increase in capacity. Things.

[0008]

The alkaline battery according to the present invention is formed by filling a positive electrode mixture and a negative electrode mixture in a bottomed cylindrical positive electrode case through a separator with being physically separated. . The separator has a cylindrical portion and a bottom surface that are respectively opposed to the cylindrical portion and the bottom surface of the bottomed cylindrical positive electrode case, and the bottom surface is in a cylindrical space surrounded by the cylindrical portion of the separator. And a bulging portion that bulges into the cylindrical space as a curved surface protruding toward the cylindrical space. The bulging portion surrounds the space surrounded by the cylindrical portion of the separator and the curved bottom surface. of the volume C, when the bottom of the separator is assumed to flat surfaces, it reduces than the volume C ₀ of the flat bottom surface and the tubular portion and drunk enclosed space. Its volume C is one that is desirable to select 3% to 10% of the volume C ₀ smaller.

In the configuration of the present invention described above, the bottom surface of the separator is not a flat surface as in the prior art, but the bottom surface of the separator is a curved surface protruding into the cylindrical space of the separator. By forming a swelling portion that swells in, the bottom surface is easily deformed.For example, when volume expansion occurs in the negative electrode mixture, the volume expansion may escape to the bottom side of the separator. it can. In this case, since the bulging portion inverts and bulges toward the bottom surface of the positive electrode case, the substantial internal volume of the separator increases by the volume of the bulging portion. Therefore, the volume expansion is effectively absorbed, and it is possible to effectively avoid pushing up the opening side of the positive electrode case due to volume expansion or the like, that is, an increase in the internal pressure to the sealing portion, and improve the liquid leakage resistance.

[0010] In the present invention, the above-mentioned liquid leakage resistance can be surely improved by setting it to about 3% or more of the space surrounded by the cylindrical portion of the separator. Due to the formation of the swelling portion that swells inward, there is concern about a decrease in the battery capacity due to a decrease in the filling amount of the negative electrode mixture due to a decrease in the initial volume of the separator. It has been found that the effect of the formation of the swelling portion on the capacity reduction in the initial state can be substantially avoided by keeping it to about 10% or less of the enclosed space.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of an alkaline battery according to the present invention, as shown in a schematic sectional view of FIG. A positive electrode mixture 2 formed into a cylindrical shape, for example, a cylindrical shape having an outer peripheral shape substantially matching the inner peripheral surface of one cylindrical portion 1a is inserted. A conductive paint is applied to the inner peripheral surface of the positive electrode case 1 or the outer peripheral surface of the positive electrode mixture 2, thereby making good electrical contact between the positive electrode case 1 and the positive electrode mixture 2.

A separator 3 is disposed in the center hole of the positive electrode mixture 2, and the separator 3 is filled with the negative electrode mixture 4 while being physically separated from the positive electrode mixture 2. The separator 3 is opposed to the cylindrical portion 1a of the positive electrode case 1 with the positive electrode mixture 2 interposed therebetween, and has a cylindrical portion 3a having an outer peripheral surface substantially matching the inner peripheral surface of the positive electrode mixture 2; 1b
And a bottom surface 3b which abuts on the bottom surface 3b.

A negative electrode current collector pin 5 is inserted into the center of the negative electrode mixture 4, and its head is connected to a negative electrode terminal plate 6 provided at a sealing portion at an opening end of the positive electrode case 1. . The sealing portion at the opening end of the positive electrode case 1 has a negative electrode terminal plate 6 and an insulating substrate 7 disposed opposite to the inner surface thereof, and a flange portion of the negative electrode terminal plate 6 abuts on a peripheral portion of the insulating substrate 7. In this state, with the peripheral portion sandwiched by the gasket 8, the opening edge of the positive electrode case 1 is swaged and sealed.
A boss 8b is formed at the center of the gasket 8,
A negative current collecting pin is penetrated through the negative current collecting pin, and the negative current collecting pin is set at the center of the battery. At the center of the bottom surface 1b of the positive electrode case 1, a convex positive electrode terminal 9 extruded outward is formed.

An outer label 10 on which a manufacturer name, a battery type, a precautionary statement, and the like are written is wound around the surface of the positive electrode case 1, and both ends are narrowed to both ends of the positive electrode case 1. Further, for example, a ring-shaped insulating plate 11 is arranged between the narrowed portion on the sealing portion side of the case 1 and the caulked portion of the positive electrode case 1 to further ensure insulation between the positive electrode case 1 and the negative electrode terminal plate 6. Configuration.

The bottomed cylindrical separator 3 is formed by folding a pair of separator pieces made of, for example, strip-shaped nonwoven fabric of vinylon, rayon or the like into a U-shape by heating and pressing, and forming a cylindrical surface. Curved,
The bottomed cylindrical separator 3 having a cylindrical shape and a bottom surface 3b formed as a whole and having a so-called rake-like configuration is formed by being overlapped with each other in an arrangement relationship rotated by 90 °.

In particular, in the present invention, the bottom surface 3b of the bottomed tubular separator 3 has, for example, a substantially spherical curved surface projecting into a tubular space surrounded by the tubular portion 3a. And the bulging portion 3c
Is formed. The bulging portion 3c can be formed at the same time as the above-mentioned heating and pressing of the separator 3. In the initial state where the volume expansion has not occurred, the bulging portion 3c has a volume C of a space surrounded by the cylindrical portion 3a of the separator 3 and the curved bottom surface 3b having the bulging portion 3c. , a configuration for reducing than the volume C ₀ of the space enclosed by this flat bottom surface 3b and the cylindrical portion 3c of assuming a bottom surface 3b of the separator 3 to have a flat surface. The volume C in this case is the volume C ₀
It is desirable to select 3% to 10% smaller.

According to the battery of the present invention, when the negative electrode mixture 4 in the separator 3 expands in volume, or when abnormal volume expansion occurs due to overdischarge, the bottom of the separator 3 expands. As shown in FIG. 2, the bulging direction is such that the portion 3c enters the outside of the cylindrical portion 3a, that is, the convex portion forming the positive electrode terminal 9 of the bottom surface 1b of the positive electrode case 1, in other words, the concave portion of the case bottom. Invert, the substantial volume of the separator 3 increases. In this case, the direction in which the volume is increased is prevented from being on the opening side of the case 1 and is released to the side opposite to the sealing portion side, so that the pressure on the sealing portion can be reduced. The effect on liquid properties can be effectively reduced.

Then, as described above, the bulging portion 3c
Is the initial state in which the volume expansion has not occurred.
c, the volume C of the space surrounded by the cylindrical portion 3a of the separator 3 and the curved bottom surface 3b having the bulging portion 3c.
Assume that the bottom surface 3b of the separator 3 is a flat surface, that is, the bottom surface 3b and the cylindrical portion 3 in the conventional structure.
3% to 10% less selected than the volume C ₀ of the space surrounded by the c. If the amount is less than 3%, the expansion of the negative electrode mixture 4 cannot secure enough space to escape due to the deformation of the bulging portion 3c of the bottom surface 3b of the separator 3.
If it exceeds 10%, there is a possibility that the filling amount of the negative electrode mixture 4 is insufficient and the purpose of obtaining an increase in battery capacity is not met, and the swelling amount of the swelling portion 3c is insufficient and long-term storage is performed. In this case, the initial shape collapses.

Next, specific examples of the alkaline battery according to the present invention will be described. In these examples, AA size batteries having the structure described in FIGS. 1 and 2 and having a battery outer diameter of 14 mm and a total battery height of 50 mm were manufactured. (Example 1) The positive electrode case 1 was formed into a bottomed cylindrical shape made of a nickel-plated steel plate. The positive electrode active material of the positive electrode mixture 2 uses natural or artificial manganese dioxide powder, graphite as a conductive material, or graphite powder such as acetylene black, and the electrolyte is a 40% aqueous solution of potassium hydroxide in a mass ratio of 86: 7. : 7 to obtain a mixture of the positive electrode mixture. The mixture of the positive electrode mixture was compression-rolled using a roll-type press or the like to produce a sheet having a thickness of about 1 mm. Next, the compressed sheet is crushed by a crusher,
Granulated. This is passed through a sieve from 60 mesh to 120
The mixture was sized into a mesh to prepare a granular positive electrode mixture.

The thus obtained granular positive electrode mixture is pressure-molded into a hollow cylinder at a predetermined pressure. A plurality of the hollow cylindrical positive electrode mixture materials 2 are inserted, and pressurized again in the positive electrode case 1 so as to adhere to the inner surface of the positive electrode case 1.

As described above, the separator 3 was formed into a bottomed cylindrical shape by pressure and heat molding using a pair of separator pieces to form the above-mentioned bulging portion 3c. Separator 3 in this case
Is 3 times larger than the volume C ₀ when the bottom surface 3b is a flat bottom surface (that is, the volume C ₀ surrounded by the cylindrical portion 3a).
%, That is, the volume (volume) of the bulging portion 3c is
It was prepared to be 3%.

Then, the gelled negative electrode mixture 4 was filled in the separator 3. This filling amount is 30 theoretical zinc volumes.
00 mAh. The gelled negative electrode mixture 4 is composed of a mercury-free zinc powder to which bismuth, indium or the like is added, a zinc oxide powder, a thickener powder made of sodium polyacrylate, and a 40% aqueous solution of potassium hydroxide. 70 by ratio
Obtained from the mixture mixed to give 2: 1: 27.

Then, a negative electrode current collector pin is inserted into the negative electrode mixture 4, the opening end of the positive electrode case 1 is sealed by the configuration described in FIG. 1, and the outer label 10 is wound around the outer surface of the positive electrode case 1. Then, an alkaline battery was prepared.

(Example 2) The same method and configuration as in Example 1 were used, except that the volume of the bulging portion 3c was changed to 5% of the volume surrounded by the cylindrical portion.

(Example 3) The same method and configuration as in Example 1 were used except that the volume of the bulging portion 3c was 10% of the volume surrounded by the cylindrical portion.

(Example 4) The same method and configuration as in Example 1 were adopted, except that the volume of the bulging portion 3c was 1% of the volume surrounded by the cylindrical portion.

(Embodiment 5) The volume of the bulging portion 3c was 13% of the volume surrounded by the cylindrical portion. Thus, the bulging portion 3
By increasing the volume of c, the filling amount of the negative electrode mixture 3 was smaller than that of Example 1, and the filling amount was 2850 mAh in terms of theoretical zinc capacity. Otherwise, the method and configuration were the same as in Example 1.

Comparative Example 1 A battery was manufactured in the same manner as in Example 1, except that the bottom of the separator 3 had a flat surface.

Table 1 shows the results of verification tests of the leak resistance and the discharge characteristics of the alkaline batteries according to the above-described Examples and Comparative Examples. In the table, n indicates the number of batteries to be measured.

The measurement of the liquid leakage resistance characteristics is performed under the condition that a new battery and a battery in use (used battery) are mixed and used, or an overdischarge state due to forgetting to switch off a used device is assumed. Overdischarging was performed under the same conditions, and the number of leaks after storage for 3 months in an environment of 45 ° C. was examined. Also,
Regarding the discharge characteristics, a constant load of 10Ω and 1000 m
AContinuous discharge at constant current and heavy load is performed and the final voltage is 0.9
The time required to reach V was measured.

[0031]

[Table 1]

From the results shown in Table 1, the bottom surface 3b of the separator 3
It can be seen that the configuration of the present invention in which the bulging portion 3c is formed on the flat bottom surface of Comparative Example 1 has improved leakage resistance characteristics. Further, the volume of the bulging portion 3c is
It is understood that a range of 3% to 10% is preferable. That is, in the configuration of the present invention, when the volume expansion occurs, the bulging portion 3
By the reverse swelling of c toward the bottom surface 1b side of the positive electrode case 1,
This volume expansion has the effect of being released or absorbed on the side opposite to the sealing portion. On the other hand, when the bottom surface of the separator 3 is a flat surface as in Comparative Example 1, since the volume expansion does not have the effect of escaping to the side opposite to the sealing portion, the leakage resistance is poor. In addition, in Example 4, since the escape of the volume expansion is not sufficient, although it is improved as compared with Comparative Example 1, it is not sufficient. In Example 5 in which the volume of the bulging portion 3c on the bottom surface of the separator 3 was 13%, the negative electrode mixture 4 was used.
The effect of dissipating the expansion into the space on the opposite side of the sealing portion to absorb the expansion amount is sufficient, and the liquid leakage resistance is improved. The discharge characteristics are degraded due to the decrease.

In the above-described example, a case where the battery is a cylindrical battery and the separator is of the crossing type is mainly described. However, various modifications such as a prismatic battery configuration and a winding type of the separator are performed. The same effect can be obtained in all cases.

[0034]

As described above, the alkaline battery according to the present invention has a bulge that projects in advance into the space surrounded by the cylindrical portion of the separator on the bottom surface of the separator, that is, on the side opposite to the sealing portion of the battery. In this way, for example, if volume expansion occurs in the negative electrode mixture due to overdischarge or the like, this volume expansion is on the bottom side opposite to the sealing portion of the separator. You can escape.

In this case, since the bulging portion is inverted and bulges toward the bottom surface of the positive electrode case, the substantial internal volume of the separator increases by the volume of the bulging portion. Therefore, the volume expansion is effectively absorbed, and it is possible to effectively avoid pushing up the opening side of the positive electrode case due to volume expansion or the like, that is, an increase in the internal pressure to the sealing portion, and improve the liquid leakage resistance.

As described above, in the configuration of the present invention, the above-mentioned liquid leakage resistance can be surely improved by setting it to about 3% or more of the space surrounded by the cylindrical portion of the separator. Also, since the swelling portion swelling inward is formed in the separator, the initial volume of the separator decreases, and the battery capacity decreases due to the decrease in the filling amount of the negative electrode mixture. By limiting the bulging portion to about 10% or less of the space surrounded by the cylindrical portion, it is possible to substantially avoid the influence on the capacity reduction in the initial state due to the formation of the bulging portion.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an example of an alkaline battery according to the present invention.

FIG. 2 is a schematic cross-sectional view of a main part showing a state of volume expansion inside an example of an alkaline battery according to the present invention.

FIG. 3 is a schematic sectional view of a conventional alkaline battery.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Positive electrode case, 1b ... Bottom surface 2 ... Positive electrode mixture, 3 ... Separator, 3a ... Cylindrical part, 3b ...
・ Bottom surface, 3c ・ ・ ・ Swelling portion, 4 ・ ・ ・ Negative electrode mixture, 5 ・ ・
・ Negative electrode current collector pin, 6 ・ ・ ・ Negative electrode terminal plate, 7 ・ ・ ・ Insulating substrate, 8 ・ ・ ・ Gasket, 8a ・ ・ ・ Boss, 9 ・ ・ ・
Positive electrode terminal, 10: exterior label, 11: ring-shaped insulating plate, 101: positive electrode case, 103b: bottom surface, 104: negative electrode mixture, 105: negative electrode current collecting pin

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hideaki Tokugawa 1-1, Shimosugishita, Takakura, Hiwada-cho, Koriyama-shi, Fukushima Prefecture Sony Energy Tech Co., Ltd. (72) Inventor Akihiro Sugawara Hiwada-cho, Koriyama-shi, Fukushima 1-1 Takakura Shimosugishita F-term in Sony Energy Tech Co., Ltd. (Reference) 5H021 BB04 CC09 HH01 HH04 5H024 CC02 CC06 CC14 DD14 HH01

Claims (3)

[Claims] A positive electrode mixture and a negative electrode mixture are physically separated in a bottomed cylindrical positive electrode case by a separator having a cylindrical portion and a bottom surface opposed to the cylindrical portion and the bottom surface of the positive electrode case, respectively. Wherein the bottom surface of the separator is a curved surface protruding into a cylindrical space surrounded by a cylindrical portion of the separator, and the inside of the cylindrical space is A bulged portion is formed, and the volume of the space surrounded by the cylindrical portion and the curved bottom surface of the separator by the bulged portion is defined assuming that the bottom surface of the separator is a flat surface. An alkaline battery having a configuration in which the volume of a space surrounded by the flat bottom surface and the cylindrical portion is reduced. 2. A volume of a space surrounded by the tubular portion and the curved bottom surface of the separator is surrounded by the flat bottom surface and the tubular portion assuming that the bottom surface of the separator is a flat surface. The alkaline battery according to claim 1, wherein the volume of the alkaline battery is reduced by 3% to 10%. 3. The alkaline battery according to claim 1, wherein a curved surface of the bulging portion of the separator is substantially spherical.