JP2000030681A - Battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery having improved safety in erroneous use such as overcharging or under an abnormally high temperature environment as in the case the battery is thrown into a fine. SOLUTION: This battery is provided with a sealing plate 7 having a vent hole 6, a terminal 8 arranged to surround the vent hole 6, and an elastic valve element 9 arranged in the compressed state to block the vent hole 6 in the space surrounded by the sealing plate 7 and the terminal 8. The elastic valve element 9 is provided with a groove section kept in contact with the sealing plate 7 astride the peripheral edge of the vent hole 6 of the sealing plate 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a battery using an elastic valve body as a safety valve mechanism.

[0002]

2. Description of the Related Art Alkaline storage batteries such as nickel cadmium storage batteries and nickel hydrogen storage batteries are known as batteries used in portable electronic equipment. If an alkaline storage battery is exposed to an abnormally high temperature environment due to misuse such as overcharging or thrown into a fire, the internal pressure rises abnormally due to the gas generated by the battery reaction, causing the metal container to rupture or the sealing member There is a risk of jumping out. For this reason,
The storage battery is provided with an explosion-proof safety valve mechanism that releases gas inside the battery in response to a pressure rise due to gas generation inside the battery and prevents damage or rupture of the battery.

As this safety valve mechanism, it is preferable to use a return-type safety valve mechanism that opens when the gas pressure in the battery reaches a predetermined value or more, releases the gas to the outside, and thereafter returns to the closed state again. FIG. 8 shows an example of a sealing member provided with a return-type safety valve mechanism. Near the center of the sealing plate 21,
A gas vent hole 22 is opened. On the sealing plate 21, a dish-shaped terminal cap 24 containing an elastic valve body 23 made of, for example, synthetic rubber or the like is welded so as to press-close the hole 22 with the elastic valve body 23. The terminal cap 24 has a plurality of gas vent holes 25 formed therein.

In an alkaline storage battery provided with such a sealing member, when gas is generated inside the battery and the internal pressure rises excessively, the elastic valve body 23 is pushed up, and the elastic valve body 23 and the sealing plate 21 are closed. A gap is formed between the gaps, and gas is released to the outside through the gap and the gas vent hole 25, thereby preventing damage or rupture.

Incidentally, the elastic valve body 23 is, for example,
It is formed from a rubber-based material mainly composed of a terpolymer (EPDM) with an ethylene-propylene-nonconjugated diene compound. The elastic valve body 23 mainly composed of EPDM has an advantage of being excellent in alkali resistance, heat resistance and durability.

[0006]

SUMMARY OF THE INVENTION However, EPD
An alkaline storage battery provided with a sealing member having a safety valve mechanism using an elastic valve body mainly composed of M is exposed to an abnormally high temperature exceeding 100 ° C. due to misuse such as overcharging or throwing into a fire. Since the elastic valve body hardens and changes in hardness and elastic modulus, the safety valve mechanism does not operate even when the gas pressure inside the battery reaches a predetermined operating pressure, resulting in damage or rupture. is there.

An object of the present invention is to provide a battery with improved safety in an abnormally high temperature environment due to misuse such as overcharging or throwing into a fire.

[0008]

A battery according to the present invention comprises a sealing plate having a gas vent hole, a terminal arranged to surround the gas vent hole, and a space surrounded by the sealing plate and the terminal. And a resilient valve body disposed in a compressed state so as to close the gas vent hole, wherein the elastic valve body has a groove that contacts the sealing plate across the periphery of the gas vent hole of the sealing plate. It is characterized by the following.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A battery according to the present invention will be described below by taking a cylindrical alkaline storage battery as an example. 1 is a cross-sectional view showing a main part of a cylindrical alkaline storage battery, FIG. 2 is a side view showing an elastic valve element incorporated in the storage battery of FIG. 1, FIG. 3 is a plan view showing the elastic valve element of FIG. FIG. 2 is a schematic diagram illustrating a relationship between a sealing plate and an elastic valve body in the storage battery of FIG. 1.

An electrode group 5 formed by spirally winding a positive electrode 2 and a negative electrode 3 between a positive electrode 2 and a negative electrode 3 with a separator 4 interposed therebetween is placed in a bottomed cylindrical metal container 1 also serving as a negative electrode terminal. It is stored. The negative electrode 3 is arranged at the outermost periphery of the electrode group 5 and is in electrical contact with the container 1. The alkaline electrolyte is contained in the container 1. A sealing member also serving as a safety valve mechanism and a positive electrode terminal includes a circular sealing plate 7 having a circular vent hole 6 opened in the center;
A hat-shaped positive electrode terminal cap 8 arranged on the sealing plate 7 so as to surround the gas vent hole 6, and the gas vent hole 6 in a space surrounded by the sealing plate 7 and the positive electrode terminal cap 8. And an elastic valve element 9 arranged in a compressed state so as to close it. The positive electrode terminal cap 8 has a plurality of gas vent holes 10. The sealing plate 7 is caulked and fixed to the container 1 via an annular insulating gasket 11. One end of the positive electrode lead 12 is connected to the positive electrode 2, and the other end is connected to the sealing plate 7.

As shown in FIG. 2 and FIG.
Has a columnar projection at the bottom. A groove 13 is formed on the lower surface of the protrusion of the elastic valve body 9 so as to cross the center of the protrusion. FIG. 4 shows the positional relationship between the sealing plate 7 and the elastic valve element 9 in the storage battery shown in FIG. The gas vent hole 6 of the sealing plate 7 is closed by a projection of the elastic valve body 9. The groove 13 is in contact with the upper surface of the sealing plate 7 across the gas vent hole 6. Accordingly, the groove 13 is in contact with two opposing edges of the gas vent hole 6 of the sealing plate 7.

Next, the positive electrode 2, the negative electrode 3, the separator 4, the alkaline electrolyte and the elastic valve 9 will be described.

1) Positive electrode 2 This positive electrode 2 contains nickel hydroxide.

The positive electrode 2 is prepared, for example, by preparing a paste containing nickel hydroxide particles, a conductive agent, a binder and water.
The paste is prepared by filling the current collector with the paste, drying and pressing the paste.

As the nickel hydroxide particles, for example, particles made of nickel hydroxide, or zinc and / or zinc hydroxide
Alternatively, nickel hydroxide particles having eutectic cobalt can be used. The latter positive electrode containing nickel hydroxide particles can further improve the charging efficiency in a high temperature state.

From the viewpoint of improving the charge / discharge efficiency of the alkaline secondary battery, the peak half-value width of the (101) plane of the nickel hydroxide by X-ray powder diffraction method is 0.8 ゜ / 2θ (Cu
-Kα) or more. A more preferable half width of the peak is 0.9 to 1.1 ° / 2θ (Cu-Kα).
It is.

Examples of the conductive agent include metallic cobalt, dicobalt trioxide (Co ₂ O ₃ ), cobalt monoxide (CoO), and cobalt hydroxide {Co (OH) ₂ }. As the conductive agent, one or more selected from the above-described types can be used. The conductive agent may be added to the paste in the form of a powder, or the surface of the nickel hydroxide particles may be coated with the conductive agent and then added to the paste.

Examples of the binder include polytetrafluoroethylene, carboxymethylcellulose, methylcellulose, sodium polyacrylate, and polyvinyl alcohol.

Examples of the current collector include those having a sponge-like, fibrous, or felt-like porous structure made of a metal such as nickel or stainless steel, a nickel-plated resin, or the like.

2) Negative electrode 3 The negative electrode 3 contains a negative electrode active material.

The negative electrode 3 is manufactured by kneading a paste with a negative electrode active material, a conductive material, a binder, and water to prepare a paste, filling the paste into a conductive substrate, drying, and then molding. .

Examples of the negative electrode active material include cadmium compounds such as metal cadmium and cadmium hydroxide, and hydrogen. Examples of the host matrix of hydrogen include a hydrogen storage alloy.

Above all, the hydrogen storage alloy is preferable because the capacity of the secondary battery can be improved as compared with the case where the cadmium compound is used. The hydrogen storage alloy is not particularly limited, and may be any as long as it can store hydrogen electrochemically generated in an electrolytic solution and can easily release the stored hydrogen during discharge. For example, LaNi ₅ , Mm
Ni ₅ (Mm is a misch metal), LmNi ₅ (Lm is at least one selected from rare earth elements including La),
A part of Ni of these alloys is Al, Mn, Co, Ti, C
Examples thereof include a multi-element-based material substituted with an element such as u, Zn, Zr, Cr, and B, or a TiNi-based or TiFe-based material. In particular, the general formula LmNi _w Co _x Mn
_y Al _z (the total value of the atomic ratios w, x, y and z is 5.00 ≦
(W + x + y + z ≦ 5.50) The hydrogen storage alloy having the composition represented by the formula (1) is suitable because it can suppress the pulverization accompanying the progress of the charge / discharge cycle and improve the charge / discharge cycle life.

Examples of the conductive material include carbon black and graphite.

Examples of the binder include polyacrylates such as sodium polyacrylate and potassium polyacrylate, fluorine resins such as polytetrafluoroethylene (PTFE), and carboxymethyl cellulose (C).
MC) and the like.

Examples of the conductive substrate include a two-dimensional substrate such as a punched metal, an expanded metal, a perforated rigid plate, and a nickel net; a felt-like porous metal;
Examples include a three-dimensional substrate such as a sponge-like porous metal body.

3) Separator 4 Examples of the separator 4 include a nonwoven fabric made of a polyamide fiber and a nonwoven fabric made of a polyolefin fiber such as polyethylene and polypropylene provided with a hydrophilic functional group.

4) Alkaline Electrolyte Examples of the alkaline electrolyte include an aqueous solution of sodium hydroxide (NaOH), lithium hydroxide (LiOH)
Aqueous solution, potassium hydroxide (KOH) aqueous solution, NaO
H and LiOH mixed solution, KOH and LiOH mixed solution, K
A mixed solution of OH, LiOH, and NaOH can be used.

5) Elastic Valve 9 This elastic valve 9 can be formed, for example, from a rubber-based material whose main component is a terpolymer (EPDM) of an ethylene-propylene-non-conjugated diene compound. The elastic valve element 9 formed of this rubber-based material has advantages of being excellent in alkali resistance and durability, hardly causing cracks, and having a high softening point, and thus having excellent heat resistance.

In FIGS. 2 and 3 described above,
One groove was formed on the lower surface of the projection of the elastic valve body, and the groove was brought into contact with the upper periphery of the gas vent hole so as to straddle the gas vent hole of the sealing plate. It does not need to straddle the vent hole, and may have any shape as long as it can straddle the periphery of the gas vent hole and contact the sealing plate. For example, as shown in FIG. 5, two grooves 15a and 15b are formed on the lower surface of the protrusion of the elastic valve body so as to face each other at a desired distance, and as shown in FIG. 6, the respective grooves 15a and 15b are formed. May be straddled over the peripheral edge of the gas vent hole 6 of the sealing plate 7 to make contact with the upper surface of the sealing plate.

Further, in FIGS. 2 and 3 described above, the groove portion of the elastic valve body is brought into contact with two portions of the peripheral edge of the gas vent hole of the sealing plate. can do. For example, as shown in FIG. 7, eight grooves 16 a to 16 h may be radially formed on the lower surface of the projection of the elastic valve element 9.

The battery according to the present invention described above has a sealing plate having a gas vent hole, a terminal arranged so as to surround the gas vent hole, and a terminal disposed in a space surrounded by the sealing plate and the terminal. An elastic valve body disposed in a compressed state so as to close the gas vent hole, wherein the elastic valve body has a groove that contacts the sealing plate across the periphery of the gas vent hole of the sealing plate. It is assumed that. According to such a battery, the battery is exposed to an abnormally high temperature environment such as misuse such as overcharging or thrown into a fire, and is placed in a state where the hardness and elastic modulus of the elastic valve body may change. At this time, the gas generated by the high temperature passes through the groove existing on the surface of the elastic valve body and is gradually released to the outside through a gas vent hole formed in the terminal, thereby suppressing an increase in valve operating pressure. And damage or rupture can be prevented.

In FIG. 1 described above, the present invention is applied to a cylindrical battery in which a separator is interposed between a positive electrode and a negative electrode, and the electrode group produced by spirally winding the separator is housed in a container. Although the example has been described, for example, the present invention may be applied to a prismatic battery in which a stack made by alternately stacking a positive electrode and a negative electrode with a separator interposed therebetween is housed in a bottomed rectangular cylindrical container. .

[0034]

Embodiments of the present invention will be described below in detail with reference to the drawings.

(Example 1) A circular sealing plate obtained by subjecting a steel flat plate to press working and having a surface plated with nickel and having a circular vent hole opened in the center was prepared. . Further, after kneading with EPDM as a main component, an organic peroxide, a vulcanization accelerator, a processing aid, and the like, press molding at about 170 ° C. as shown in FIGS. An elastic valve body having a columnar projection and a groove formed so as to cross the center on the lower surface of the projection was manufactured. The rubber hardness of the elastic valve body was set to 70 degrees. On the other hand, a dish-shaped (hat-shaped) terminal cap obtained by pressing a steel flat plate and having its surface plated with nickel was prepared.

Next, the elastic valve body was inserted into the terminal cap. With this terminal cap, the projection of the elastic valve body presses and closes the gas vent hole of the sealing plate, and the groove contacts the upper surface of the sealing plate across the gas vent hole as shown in FIG. 4 described above. Was placed on the sealing plate.
Subsequently, the periphery of the flange portion of the terminal cap and the sealing plate were integrated by spot welding to produce a sealing member having a safety valve mechanism.

(Embodiment 2) As shown in FIG.
An elastic valve body similar to that of Example 1 was produced except that two grooves were formed as shown in FIG.

Next, the elastic valve body was inserted into a terminal cap similar to that described in the first embodiment. In this terminal cap, the projection of the elastic valve body presses and closes the gas vent hole of the sealing plate similar to that described in the first embodiment, and each of the grooves is formed of the sealing plate as shown in FIG. The sealing plate was placed on the sealing plate so as to be in contact with the upper surface of the sealing plate over the periphery of the gas vent hole. Subsequently, the periphery of the flange portion of the terminal cap and the sealing plate were integrated by spot welding to produce a sealing member having a safety valve mechanism.

(Comparative Example) An elastic valve body similar to that of Example 1 was manufactured except that no groove was formed on the lower surface of the projection.

Next, the elastic valve body was inserted into a terminal cap similar to that described in the first embodiment. The terminal cap was placed on the sealing plate so that the projection of the elastic valve body pressed and closed the gas vent hole of the sealing plate similar to that described in Example 1. Subsequently, the periphery of the flange portion of the terminal cap and the sealing plate were integrated by spot welding to produce a sealing member having a safety valve mechanism.

FIG. 9 shows the transition of the valve operating pressure when the ambient temperature was gradually increased from 25 ° C. to 200 ° C. for the obtained sealing members having the safety valve mechanism of Examples 1 and 2 and Comparative Example. .

As is clear from FIG. 9, the valve operating pressure at 200 ° C. of the safety valve devices of the first and second embodiments of the present invention is about 1
Whereas a 5 kgf / cm ^2, the valve operating pressure at 200 ° C. of the safety valve device of the comparative example is about 25 kgf / cm ^2, the safety valve device in Examples 1 and 2 the valve with increasing temperature as compared with Comparative Example It can be seen that an increase in the operating pressure can be suppressed.
Further, it is considered that this difference is further increased in a higher temperature region. According to the safety valve devices of the first and second embodiments,
Even if the internal pressure rises excessively due to the gas generated by the battery being exposed to an abnormally high temperature, the gas is gradually released to the outside through the groove existing on the surface of the elastic valve body. This is because it can be avoided.

In the above-described embodiment, the terminal cap is fixed to the sealing plate by welding. However, the fixing method is not limited to this. For example, the terminal cap may be fixed by caulking.

[0044]

As described in detail above, according to the present invention, it is possible to prevent erroneous use such as overcharging, and damage or rupture when exposed to an abnormally high temperature due to being thrown into a fire.
A battery with improved safety can be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a main part of a battery according to the present invention.

FIG. 2 is a side view showing an elastic valve body incorporated in the battery of FIG.

FIG. 3 is a plan view showing the elastic valve body of FIG. 2;

FIG. 4 is a schematic diagram showing a positional relationship between a sealing plate and an elastic valve body in the battery of FIG.

FIG. 5 is a plan view showing another elastic valve body incorporated in the battery according to the present invention.

FIG. 6 is a schematic diagram showing a positional relationship between the elastic valve body and the sealing plate of FIG. 5;

FIG. 7 is a plan view showing still another elastic valve body incorporated in the battery according to the present invention.

FIG. 8 is a sectional view showing a sealing member provided with a safety valve mechanism incorporated in a conventional battery.

FIG. 9 is a characteristic diagram showing a change in valve operating pressure when an ambient temperature is changed in a sealing member provided with the safety valve mechanisms of Examples 1 and 2 and a comparative example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Container, 2 ... Positive electrode, 3 ... Negative electrode, 4 ... Separator, 6 ... Gas vent hole, 7 ... Sealing plate, 9 ... Elastic valve body.

Claims (1)

[Claims] 1. A sealing plate having a gas vent hole, a terminal arranged to surround the gas vent hole, and a compression so as to close the gas vent hole in a space surrounded by the sealing plate and the terminal. And a resilient valve body disposed in a state, wherein the resilient valve body has a groove that straddles the periphery of a gas vent hole of the sealing plate and contacts the sealing plate.