JP5344003B2 - Alkaline battery - Google Patents

Description

  The present invention relates to an alkaline battery.

  In conventional alkaline batteries, when a plurality of batteries are connected in series, for example, only one battery is attached in the opposite direction to the other battery. There is a risk that gas generation inside the dry battery or leakage of a strong alkaline electrolyte (such as potassium hydroxide or sodium hydroxide) may occur.

  Therefore, in a conventional alkaline battery, a thermosensitive microcapsule that releases a substance contained when the temperature in the battery rises is contained in the electrolyte, and a curing reaction such as a polymerization reaction or a crosslinking reaction is included in the microcapsule. There is known a substance that encloses a chemical substance that causes oxidization (see, for example, Patent Document 1). For example, the conventional alkaline dry battery shown in Patent Document 1, for example, shortens the internal resistance of the battery by increasing the internal resistance of the battery by solidifying the electrolyte with a chemical substance released from the microcapsule when the temperature in the battery rises. It is intended to prevent energy from being consumed in time.

  Similarly, as an alkaline dry battery in which a thermosensitive microcapsule is contained in an electrolytic solution, a battery in which a substance that inhibits a battery reaction is included in the microcapsule is also known (see, for example, Patent Document 2). . For example, the conventional alkaline dry battery shown in Patent Document 2, for example, inhibits the battery reaction by a substance released from the microcapsule when the temperature in the battery rises, so that the thermal runaway start temperature even when heat is generated due to battery abnormality. It is intended not to reach to.

  Note that the microcapsules used in the batteries described in Patent Document 1 and Patent Document 2 are, for example, as shown in FIG. 6, filled with a core material 9b in a film material 9a formed in a capsule shape. Configured. The shape of this microcapsule is substantially spherical.

  In the above, heat-sensitive microcapsules that release the inclusion substance in response to the temperature in the battery are used. In order to release the inclusion substance when gas is generated in the battery. Also known are those using pressure-sensitive microcapsules that release an encapsulated substance in response to an increase in pressure in the battery.

Japanese Patent Laid-Open No. 06-283206 JP-A-10-270084

  However, in the conventional alkaline batteries shown in Patent Document 1 and Patent Document 2, when the pressure or temperature in the battery rises, the pressure or temperature of the entire electrolyte does not rise uniformly, so all the microcapsules However, there is a problem that the whole electrolyte solution cannot be neutralized or cured quickly and efficiently.

  The present invention has been made to solve such a problem, and obtains an alkaline dry battery that can efficiently neutralize the entire alkaline electrolyte inside the dry battery when the pressure inside the dry battery rises. It is.

  In the alkaline dry battery according to the present invention, a positive electrode having a positive electrode active material, a gelled negative electrode having a gelled alkaline electrolyte and a negative electrode active material, and contained in the gelled negative electrode, the electrolyte solution Including a core material having a component capable of neutralizing, and a microcapsule capable of releasing the core material when a predetermined pressure is applied to the surface, the microcapsule having a surface shape having different curvatures It is set as the structure which is.

  The alkaline dry battery according to the present invention has an effect that the entire alkaline electrolyte can be efficiently neutralized inside the dry battery when the pressure inside the dry battery rises.

It is a fragmentary sectional view by the side of the negative electrode of the alkaline dry battery which concerns on Embodiment 1 of this invention. It is sectional drawing of the microcapsule used for the alkaline dry battery which concerns on Embodiment 1 of this invention. It is sectional drawing of the microcapsule used for the alkaline dry battery which concerns on Embodiment 2 of this invention. It is sectional drawing of the alkaline dry battery which concerns on Embodiment 3 of this invention. It is sectional drawing of the alkaline dry battery which concerns on Embodiment 4 of this invention. It is sectional drawing of the microcapsule used for the conventional alkaline battery.

  The present invention will be described with reference to the accompanying drawings. Throughout the drawings, the same reference numerals indicate the same or corresponding parts, and the overlapping description is simplified or omitted as appropriate.

Embodiment 1 FIG.
1 and 2 relate to Embodiment 1 of the present invention. FIG. 1 is a partial sectional view of an alkaline battery, and FIG. 2 is a sectional view of a microcapsule.
In FIG. 1, 1 is a positive electrode can which consists of a bottomed substantially cylindrical metal can which the upper part opened. The positive electrode can 1 also serves as a positive electrode terminal. The positive electrode can 1 is filled with a positive electrode mixture 2 that is pressure-molded into a substantially cylindrical shape. This positive electrode mixture 2 is a mixture of manganese dioxide powder, which is a positive electrode active material, and graphite powder, and is formed into a hollow cylindrical shape.

  A gelled negative electrode 4 is filled in the hollow portion of the positive electrode mixture 2 via a substantially cylindrical separator 3. This gelled negative electrode 4 is composed of an electrolytic solution made into a gel by adding a superabsorbent polymer such as polyacrylic acid to an aqueous solution of potassium hydroxide or sodium hydroxide, and zinc or a zinc alloy as a negative electrode active material. It is configured. A brass negative electrode current collector 5 is inserted in the center of the gelled negative electrode 4.

A gasket 6, a metal support 7, and a negative electrode terminal 8 are disposed on the opening side of the positive electrode can 1.
The gasket 6 is disposed between the outer peripheral surface of the negative electrode current collector 5 and the inner peripheral surface of the positive electrode can 1 on the opening side of the positive electrode can 1, and prevents leakage of electrolyte solution or the like in the battery. . A thin portion 6 a having a small thickness is formed in a portion of the gasket 6 near the outer periphery of the negative electrode current collector 5. The thin portion 6a is for breaking when the pressure in the battery is abnormally increased, and for releasing the battery internal pressure to the outside.

The metal support 7 is fixed to the inner periphery of the opening of the positive electrode can 1 via the outer peripheral end of the gasket 6 and supports the negative electrode current collector 5.
The negative electrode terminal 8 covers the opening of the positive electrode can 1 on the outermost side and is in contact with the negative electrode current collector 5. Similarly to the metal support 7, the negative electrode terminal 8 is also fixed through the outer peripheral end of the gasket 6 on the inner periphery of the opening of the positive electrode can 1.

  In addition, when the thin part 6a of the gasket 6 in the metal support 7 and the negative electrode terminal 8 is broken, the support vent hole 7a and the terminal vent hole 8a are respectively connected to the portion from the thin part 6a to the outside of the battery. It has been drilled.

  In the gelled negative electrode 4, a large number of microcapsules 9 that are ruptured in response to pressure are mixed. As shown in FIG. 2, the microcapsule 9 is configured by filling a core material 9b into a film material 9a made of a film-like body formed in a capsule shape. As the core material 9 b included in the microcapsule 9, any chemical substance can be used as long as the alkaline electrolyte contained in the gelled negative electrode 4 can be neutralized.

  For example, alkaline hydroxide can be eliminated by using a fat or a mixture thereof as the core material 9b and causing a saponification reaction with an alkaline electrolyte. In this case, as fats and oils to be used, for example, non-drying animal oils containing unsaturated fatty acids such as linoleic acid, linolenic acid and oleic acid and saturated fatty acids such as stearic acid and palmitic acid, and salad oil, soybean oil, lard, etc. Non-drying vegetable oils containing saturated fatty acids are preferred.

  When the pressure applied from the outside to the membrane material 9 a exceeds a predetermined constant value, the microcapsule 9 is ruptured and the inner core material 9 b is released to the outside of the microcapsule 9. Here, the material used for the membrane material 9a of the microcapsule 9 is a material that can explode quickly when the internal pressure of the battery reaches a predetermined abnormal pressure and release the core material 9b that is the inclusion. It is preferable to do. Further, it is preferable in terms of characteristics to select a material that does not dissolve in the alkaline electrolyte of the gelled negative electrode 4. Specifically, for example, melamine resin, epoxy resin, urethane resin or the like can be used as the film material 9a.

  The size of the microcapsule 9 is not limited as long as it can efficiently discharge the core material 9b to neutralize the electrolyte and does not affect the electric capacity of the battery, and preferably 1 μm or more and 100 μm. It is about the following.

  The shape of the microcapsule 9 is not spherical, but is formed in a spheroid shape (oblong shape, oblong shape) having an elliptical cross section as shown in FIG. In the case of the spherical microcapsule 9, the pressure applied to the membrane material 9 a from the outside is uniformly uniform with respect to the surface of the microcapsule 9. On the other hand, if the shape of the microcapsule 9 is a spheroid, the distribution of pressure applied to the film material 9a is not uniform with respect to the surface of the microcapsule, and therefore the pressure is partially (specifically In particular, the film material 9a is likely to burst due to concentration on the portion having a large curvature.

  The shape of the microcapsule 9 is a spheroid shape here, but the shape is not limited to a spheroid shape as long as it has a surface shape having a portion with a different curvature on the surface. If the surface shape has a portion with a different curvature on the surface, the pressure applied to the portion where the curvature is larger than the others (in other words, the radius of curvature is small) is greater than the pressure applied to the other portions of the surface. The film material 9a at the location is likely to burst.

  Furthermore, by making the shape of the microcapsule 9 indefinite, the maximum value of the pressure applied to the surface of the plurality of microcapsules 9 can be made different for each microcapsule. And by making the maximum value of the pressure applied to the surface different for each microcapsule, many microcapsules 9 are gradually ruptured as the pressure in the battery increases, and the electrolytic solution of the gelled negative electrode 4 gradually Can be neutralized.

  The shape of the microcapsule 9 greatly depends on the manufacturing method and the material constituting the membrane material 9a of the microcapsule 9. An existing manufacturing method can be used as a manufacturing method of the microcapsule. Among these, it is particularly preferable to manufacture the microcapsule 9 using an in situ polymerization method, a coacervation method, or the like. As the material of the membrane material 9a, it is preferable to select a material that bursts quickly when a predetermined pressure is applied to the surface and does not dissolve in the alkaline electrolyte as described above.

  In the alkaline dry battery configured as described above, the microcapsule 9 is not ruptured under normal conditions, and the core material 9b in the microcapsule 9 is protected by the film material 9a. Therefore, the core material 9b in the microcapsule 9 does not come into contact with the alkaline electrolyte of the gelled negative electrode 4, the battery reaction proceeds without being inhibited, and can be used as an alkaline battery.

  When the pressure inside the dry battery rises due to misuse such as reverse insertion of the battery and the pressure applied to the surface of the microcapsule 9 exceeds a certain value, the membrane material 9a of the microcapsule 9 is ruptured and contained. The core material 9b is discharged into the gelled negative electrode 4. At this time, since the microcapsule 9 has a surface shape such as a spheroid having portions with different curvatures on the surface, the pressure applied to one microcapsule 9 varies depending on the curvature of the surface shape. Come. Therefore, when the maximum pressure applied to the surface of a certain microcapsule 9 exceeds the strength of the membrane material 9a, the microcapsule 9 is ruptured and the core material 9b contained therein is released. Further, when the shape of the microcapsule 9 is indefinite, the bursting pressure differs for each microcapsule.

  Thus, when the pressure inside the dry battery rises and the core material 9b encapsulated by the membrane material 9a of the microcapsule 9 ruptures is discharged into the gelled negative electrode 4, the discharged core material 9b and the gel are discharged. Reaction with the alkaline electrolyte of the negative electrode 4 (for example, saponification reaction when oil or fat is used for the core 9b) causes neutralization of the alkaline electrolyte. And the electrolysis which generate | occur | produces gas inside a battery can be suppressed by neutralizing alkaline electrolyte.

  The alkaline dry battery configured as described above includes a positive electrode having a positive electrode active material, a gelled negative electrode having a gelled alkaline electrolyte and a negative electrode active material, and a gelled negative electrode. And a microcapsule capable of releasing the core material when a pressure exceeding a predetermined level is applied to the surface. And this microcapsule has the surface shape which has a location from which a curvature differs.

  For this reason, when the pressure inside the dry cell rises, a large pressure is applied to the portion where the curvature of the surface of the microcapsule is large. Therefore, the pressure responsiveness of the microcapsule is improved and the microcapsule bursts quickly, The entire alkaline electrolyte can be efficiently neutralized.

Embodiment 2. FIG.
FIG. 3 is a cross-sectional view of a microcapsule according to Embodiment 2 of the present invention.
In the second embodiment described here, in the configuration of the first embodiment described above, a microcapsule includes a small piece body together with a core material.
That is, as shown in FIG. 3, in the film material 9a of the microcapsule 9, a small piece 10 that is a solid columnar or needle-like solid is enclosed together with the core material 9b. For example, glass fiber is used as the material of the small piece body 10. By enclosing the small piece 10 in the microcapsule 9 in this way, when the pressure inside the dry battery rises and the pressure is applied to the surface of the microcapsule 9, the inner wall of the membrane material 9a comes into contact with the small piece 10, and this contact portion Therefore, the membrane material 9a is easily ruptured.

  Since the small piece body 10 is encapsulated in the microcapsule 9, the longitudinal dimension of the small piece body 10 is naturally required to be shorter than the major axis (diameter) dimension of the core material 9 b of the microcapsule 9. For example, when the long diameter (the diameter) of the core member 9b is 50 μm, the longitudinal dimension of the small piece 10 is set to be less than 50 μm. However, as described above, in this embodiment, when the pressure is applied to the surface of the microcapsule 9, the small piece 10 is brought into contact with the inner wall of the membrane material 9a, thereby urging the microcapsule 9 to burst. Even if the size of the small piece 10 is too short, the effect of accelerating the bursting is reduced. Accordingly, it is preferable that the dimension of the small piece body 10 is approximately equal to or slightly smaller than the dimension of the core material 9b.

  Here, an example in which a glass fiber is used as the material of the small piece body 10 has been described. However, when the pressure is applied to the surface of the microcapsule 9, the small piece body 10 comes into contact with the inner wall of the membrane material 9a, thereby causing the microcapsule. The material of the small piece 10 is not limited to glass fiber as long as it promotes the rupture of 9.

  In addition, the shape of the small piece 10 is likely to come into contact with the inner wall of the membrane material 9a when pressure is applied to the surface of the microcapsule 9, and affects the capacity of the core material 9b included in the microcapsule 9 as much as possible. Something like that is desirable. Accordingly, as described herein, a thin columnar shape or a needle shape is preferable.

  Other configurations are basically the same as those in the first embodiment. However, in this second embodiment, the microcapsule 9 is ruptured by the action of the small piece body 10, and therefore the shape of the microcapsule 9 is the same. As for, it is not always necessary to have a spheroid shape or the like, and it may be spherical.

  The alkaline dry battery configured as described above is obtained by enclosing a small piece together with a core in a microcapsule. For this reason, when the pressure inside the dry battery rises, the inner wall of the microcapsule membrane material comes into contact with the small piece and the microcapsule is easily ruptured. Therefore, the pressure responsiveness of the microcapsule is improved and the microcapsule ruptures quickly. In addition, the entire alkaline electrolyte can be efficiently neutralized inside the dry battery.

Embodiment 3 FIG.
FIG. 4 is a cross-sectional view of an alkaline battery according to Embodiment 3 of the present invention.
In Embodiment 3 described here, in the configuration of Embodiment 1 or Embodiment 2 described above, a number of solid substances that promote the bursting of microcapsules are contained in the gelled negative electrode. .

  That is, as shown in FIG. 4, a large number of solid substances 11 are mixed in the gelled negative electrode 4. Since the solid material 11 must be an insulator that can withstand the increase in internal pressure and does not participate in the battery reaction, it is preferable to use a synthetic resin such as nylon resin or a synthetic rubber as a material. When the solid material 11 is put into the gelled negative electrode 4 in this way, the pressure inside the dry battery rises and pressure is applied to the surface of the microcapsule 9, and the outer wall of the membrane material 9 a of the pressed microcapsule 9 becomes solid material 11. The film material 9a is easily ruptured from this contact portion.

  When the solid material 11 comes into contact with the outer wall of the membrane material 9a, the solid material 11 is formed into a shape having a pointed tip, for example, a triangular pyramid shape, so that the burst of the microcapsule 9 can be further promoted. preferable.

  The other configurations are basically the same as those in the first embodiment and the second embodiment, but in this third embodiment, the action of the solid material 11 promotes the bursting of the microcapsules 9, The shape of the microcapsule 9 does not necessarily have to be a spheroid, and may be spherical.

  The alkaline dry battery configured as described above has a gelled negative electrode mixed with a solid material. For this reason, when the pressure inside the dry battery rises, the outside of the microcapsule membrane material comes into contact with the solid matter in the gel-like negative electrode, and the microcapsules are easily ruptured. The capsule bursts quickly, and the entire alkaline electrolyte can be efficiently neutralized inside the dry battery.

Embodiment 4 FIG.
FIG. 5 is a cross-sectional view of an alkaline battery according to Embodiment 4 of the present invention.
In Embodiment 3 described here, in the configuration of Embodiments 1 to 3 described above, a partition for preventing the distribution of microcapsules in the gelled negative electrode from being biased is used as the gelled negative electrode. At least one or more are provided.

  That is, as shown in FIG. 5, at least one or more partition bodies 12 having a film shape or a plate shape are provided in the gelled negative electrode 4 containing the microcapsules 9. The partition body 12 prevents the microcapsule 9 from going back and forth across the partition body 12, but the electrolyte solution of the gelled negative electrode 4 can freely go back and forth across the partition body 12. . Specifically, the partition body 12 is provided with one or more liquid passage holes 12a for allowing the electrolytic solution to pass therethrough. The liquid passage hole 12 a allows the electrolytic solution of the gelled negative electrode 4 to pass therethrough, but has an inner diameter smaller than the outer diameter of the microcapsule 9.

  The partition 12 is made of a material that does not inhibit the battery reaction (for example, nylon resin). Specifically, for example, when a microcapsule having an outer diameter (diameter) of 60 μm is included in the gelled negative electrode 4, a liquid passage hole 12 a having a diameter of 50 μm is provided in the partition body 12 and then molded into a disk shape. Thereby, the partition 12 as shown in FIG. 5 is formed. Then, at least one or more partition bodies 12 configured in this manner are mounted in the gelled negative electrode 4.

  In addition, the shape of the liquid passage hole 12 a provided in the partition 12 may be, for example, a slit shape in which the interval dimension is smaller than the size of the microcapsule 9 in addition to the circular shape. Further, by providing protrusions or irregularities on the surface of the partition body 12, the microcapsules 9 that are in contact with the surface of the partition body 12 may be easily ruptured.

  Other configurations are basically the same as those in the first to third embodiments, and detailed description thereof is omitted.

  The alkaline dry battery configured as described above is provided with a partition body that prevents the passage of the microcapsules in the gelled negative electrode and does not prevent the passage of the electrolyte solution of the gelled negative electrode. For this reason, the microcapsules do not collect in one place in the gelled negative electrode but are uniformly dispersed and neutralize the entire alkaline electrolyte efficiently inside the dry cell when the pressure inside the dry cell rises. Can be made. In addition, even microcapsules located in places where the pressure does not easily rise when gas is generated inside the battery are easily ruptured because they come into contact with the partition and are pressed, and the entire electrolyte can be quickly removed. Can be neutralized.

DESCRIPTION OF SYMBOLS 1 Positive electrode can 2 Positive electrode mixture 3 Separator 4 Gel-like negative electrode 5 Negative electrode current collector 6 Gasket 6a Thin part 7 Metal support body 7a Support body ventilation hole 8 Negative electrode terminal 8a Terminal ventilation hole 9 Microcapsule 9a Film material 9b Core material 10 Small piece body 11 Solid matter 12 Partition 12a Liquid passage hole

Claims (8)

A positive electrode having a positive electrode active material;
A gelled negative electrode having a gelled alkaline electrolyte and a negative electrode active material;
A microcapsule which is contained in the gelled negative electrode and contains a core material having a component capable of neutralizing the electrolytic solution, and which can release the core material when a predetermined pressure or more is applied to the surface,
The alkaline dry battery, wherein the microcapsule has a surface shape having portions with different curvatures.   The alkaline dry battery according to claim 1, wherein the microcapsule has a substantially spheroid shape.   2. The alkaline dry battery according to claim 1, wherein the microcapsule has an irregular shape, and a plurality of the microcapsules are provided in the gelled negative electrode.   The alkaline dry battery according to any one of claims 1 to 3, further comprising a small piece encapsulated together with the core material in the microcapsule.   The alkaline dry battery according to claim 4, wherein the small piece has a thin columnar shape or a needle shape.   The alkaline dry battery according to any one of claims 1 to 5, further comprising a solid substance mixed in the gelled negative electrode.   The alkaline dry battery according to claim 6, wherein the solid material has protrusions or irregularities on the surface.   The partition body provided in the said gelled negative electrode, the passage of the said microcapsule is prevented, and the passage of the said electrolyte solution of the said gelled negative electrode is provided. The alkaline dry battery according to any one of the above.

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