JP2005216775A - Sealed storage battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sealed alkali storage battery, especially, a nickel-hydrogen storage battery having high capacity, safety, and reliability, excellent in heat resistant property and shock resistant property, of which, safety is maintained and sealing property is quickly recovered even if an inner pressure is abruptly increased by quick charging. <P>SOLUTION: The battery case 1 of the storage battery is sealed by a lid body 3 breaking a current flow when inner pressure of the battery is increased. The lid body has a sealing plate 4 and a cap 5, and the cap having a vent hole 15 serves as an electric terminal of one polarity by being jointed to the sealing plate. A spring 8 of which, at least upside or lower side is electrically insulated, and a valve plate 9 not contacting the cap having insulating sealing members around upper periphery are arranged in the cap. The sealing plate is connected to an electrode of one polarity, and a valve vent formed on the sealing plate is pressed and sealed by the spring. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention particularly relates to a sealed alkaline storage battery having a built-in charge control function.

Nickel cadmium storage batteries and nickel hydride storage batteries are commonly used in sealed alkaline storage batteries in large quantities. In particular, nickel-metal hydride batteries have a higher energy density than nickel-cadmium storage batteries, and do not contain harmful cadmium and are less likely to cause environmental pollution. Therefore, portable electronic devices such as mobile phones, small power tools, and small personal computers are used. It is widely used as a power source for equipment, and the demand is dramatically increasing. In addition, these electronic devices are reduced in power consumption due to the progress of miniaturization and weight reduction, while the power consumption is increased due to multifunctionalization. For this reason, the storage battery used for these is required to have good rapid charging performance as well as a small size and high capacity.
In particular, in recent years, there has been an increasing demand for charging a consumer-use small-sized storage battery in an unprecedented short time of 15 to 30 minutes. If the sealed storage battery is charged rapidly as described above, the battery performance may deteriorate due to heat generation during charging and the temperature of the battery rising, or the electrolytic solution being decomposed and discharged outside the battery. In addition, it has been difficult to charge a conventional battery in such a rapid manner.

  In order to enable such rapid charging as described above, a charge control method based on mechanical control inside a storage battery has been proposed for a sealed storage battery. This method is a method in which charging current is interrupted by utilizing movement of the grommet which is hermetically and liquid tightly sealed while electrically insulating the cap and the battery case can. (For example, refer to Patent Document 1). Specifically, as shown in FIG. 7, the gasket 26 is extended in the center direction to form a thin portion 26 ′, and the electrode plate group is inserted into the through hole provided in the center portion of the gasket 26 via the lead plate 27. The connection terminal 29 connected to 30 is inserted. The connection terminal is normally pressed downward in the figure by the rubber elastic body 23, and the metal plate terminal 28 joined to the connection terminal 29 is brought into contact with the cap 21 also serving as an external terminal. A circuit that contacts the sealing plate 22 and connects the electrode plate group 30 and the cap 21 is formed. When the internal pressure of the battery rises during charging, the thin part 26 'bends upward in the figure, and the connection terminal 29 inserted through the through hole of the gasket moves upward so that the plate-like terminal 28 and the sealing plate 22 are moved. The circuit is disconnected by dissociation.

US Patent Application Publication No. 2002 / 0119364A1

  As is well known, in a sealed alkaline storage battery, a so-called charge reserve and discharge reserve capacity are provided at the negative electrode in order to treat the generated gas at the end of charging and to prevent overcharge and overdischarge. The charging reservoir is an uncharged surplus capacity provided to the negative electrode so that hydrogen is not generated from the negative electrode at the end of charging of the storage battery positive electrode or during overcharging. The discharge reserve is provided in preparation for the capacity decrease of the negative electrode, or in response to the overdischarge of the storage battery.

  In the case of a nickel metal hydride storage battery, the surface of nickel hydroxide used as a positive electrode active material is usually coated with a cobalt compound such as cobalt hydroxide in order to increase conductivity and improve utilization. This cobalt compound is oxidized during initial charging and oxidized (charged) into cobalt oxyhydroxide. Usually, this reaction is irreversible, and the amount of charge required for this reaction is a potential discharge amount of electricity in the negative electrode. Part of the discharge reserve. When the charge / discharge cycle elapses, corrosion of the hydrogen storage alloy of the negative electrode proceeds, and hydrogen generated by the reaction is stored in the hydrogen storage alloy. This results in a decrease in the negative electrode active material, resulting in a decrease in charge reserve and an increase in discharge reserve.

  In order to improve the output per mass or volume of the storage battery, it is necessary to increase the portion of the active material that can contribute to the output as much as possible. In the case of the above-described nickel metal hydride storage battery, in order to achieve this, it is necessary to compress the charge reserve and the discharge reserve as much as possible to ensure a proportion of the active material that can contribute to the discharge. However, with such a configuration, it has been difficult to obtain sufficient cycle life characteristics. In addition, depending on the application and usage conditions, it is possible to use the device effectively by performing rapid charging, but if the capacity per unit volume of the storage battery increases, the required charging current increases, and heat generation in the battery occurs. Also increases with this. In the nickel-metal hydride battery, heat generated due to the hydrogen occlusion of the hydrogen occlusion alloy is also added, the battery temperature rises and the charging efficiency is lowered, and the internal pressure of the battery rapidly rises due to gas generation, which may cause a safety problem. In the configuration of Patent Document 1, since the ratio of the grommet that covers the upper part of the storage battery and seals the cap and the battery case can airtight and liquid tightly while electrically insulating is large, the height of the electrode group is increased. There is a problem that it is necessary to reduce the capacity, which is not suitable for improving the capacity per volume, and that the number of parts used is high, the cost is high, the structure is complicated, and the production efficiency at the time of assembly is poor. In addition, due to the safety of the storage battery itself and environmental considerations, there are strict requirements for safety when exposed to high temperatures or when subjected to a strong mechanical shock.

  The problem to be solved is that a sealed alkaline storage battery, particularly a sealed nickel-metal hydride storage battery, has a structure in which the safety of the battery is maintained and the sealing performance is quickly restored when there is a sudden increase in internal pressure due to rapid charging. The battery capacity is impaired, the structure is complicated and difficult to obtain at low cost, and the structure is not necessarily perfect for heat resistance and impact resistance.

  Claim 1 of the present invention for solving the above-mentioned problem is a battery in which a battery case can is sealed with a lid that cuts off current when the battery internal pressure rises, and the lid has a sealing plate and a cap. The cap provided with the exhaust hole is joined to the sealing plate to form an electrical terminal of one polarity, and in the cap, the strip having at least one of the upper and lower sides electrically insulated and the cap without contact with the cap A valve plate provided with an insulating sealing member around the upper surface; the valve plate is electrically connected to the electrode of the polarity; and the valve port provided on the sealing plate is pressed and closed by the protrusion. This is a sealed storage battery.

  According to a second aspect of the present invention, there is provided the sealed storage battery according to the first aspect, wherein a flexible insulating plate that swings in close contact with the inner periphery of the cap serves as both insulation below the ridge and an insulating sealing member.

  According to a third aspect of the present invention, there is provided the sealed storage battery according to the second aspect, wherein a flexible insulating plate normally covers and seals the exhaust hole.

  According to a fourth aspect of the present invention, in the sealed storage battery according to the second or third aspect, the peripheral edge of the flexible insulating plate forms a skirt extending in close contact with the inner periphery of the cap.

  Claim 5 is the sealed storage battery according to any one of claims 1 to 3, wherein the battery is a nickel metal hydride storage battery.

  According to the first aspect, it is possible to obtain an inexpensive and safe sealed storage battery capable of being rapidly charged with a large current and having a high energy density per volume even when the battery is exposed to an excessively high temperature.

  According to the second to fourth aspects, in addition to the effect of the first aspect, it is possible to obtain a highly reliable sealed storage battery that is particularly excellent in hermeticity and less likely to leak.

  According to the fifth aspect, in addition to the effect of any one of the first to fourth aspects, it is possible to obtain a highly reliable sealed nickel-metal hydride storage battery that can be rapidly charged with a large current and has a long cycle life.

  An example of an embodiment of the present invention will be described with reference to the drawings. Each figure shows the structure and operation by the longitudinal section of the principal part of the present invention, and FIG. 1 shows a pause of one embodiment of the present invention and a normal charge / discharge state. FIG. 2 shows the rest of the implementation and the normal charge / discharge state, FIG. 3 shows the state where the internal pressure of the battery exceeds a predetermined value at the time of charging and the charge is cut off, and FIG. This shows a state where gas generated in the battery is discharged out of the battery due to a rise in internal pressure. 4 shows still another embodiment of the present invention, and FIG. 5 shows still another embodiment.

(First embodiment)
FIG. 1 is a diagram showing a first embodiment of the present invention. In FIG. 1A, reference numeral 1 denotes a metal battery case that houses an electrode group 2 in which a positive electrode and a negative electrode are wound spirally through a separator. 3 is a metal lid which is composed of a sealing plate 4 and a cap 5 and is airtightly and conductively joined. The metal lid 3 covers the upper open end side (the portion shown in the figure) of the battery case 1 and is made of synthetic resin or the like. The battery case 1 is caulked and fixed to the upper edge of the battery case 1 through a gasket 6 made of an insulator. A valve port 7 is provided in a part of the sealing plate 4, preferably in the center thereof. A small-diameter exhaust hole 15 is formed in the side surface of the cap 5, and a space formed by the cap 5 and the sealing plate 4 is formed by a ridge in a compressed state, preferably by a metal ridge 8 such as a coil spring or a disc spring. A metal valve plate 9 made of metal or the like is pressed against the sealing plate 4 so as to close the valve port 7 to electrically connect the two and to seal the battery. An annular insulator 11 that is in close contact with the inner periphery of the cap 5 is fixed around the upper surface of the valve plate 9. The insulator 11 prevents the cap 5 and the valve plate 9 from contacting each other when the valve plate 9 moves up and down, and maintains electrical insulation between them. Moreover, since the airtightness of a battery can be improved by making the peripheral part 11a of the annular insulator 11 contact | abut to the inner wall of the cap 5, it is a preferable form. As the annular insulator 11, a molded body of synthetic resin such as polypropylene, polyamide, or polyester, or a molded body of rubber such as natural rubber or synthetic rubber can be applied. The valve plate 9 is electrically connected to the positive electrode constituting the electrode group 2 by the lead plate 10, and the cap 5 serves as a terminal of one electrode (positive electrode). The other terminal (negative electrode) is a battery case 1. An insulating sheet 12 is inserted between the upper part of the ridge 8 and the upper inner surface of the cap 5.

  In addition, in order to ensure the airtightness between the metal valve plate 9 and the sealing plate 4, it is necessary to sufficiently smooth the contact surfaces of both. As shown in FIG. 1 (b), the side surface of the metal valve plate 9 and the valve port 7 provided in the sealing plate 4 (in FIG. 1 (b), the valve port 7 is filled with the valve plate 9). If the valve plate 9 and the valve port 7 are shaped like a truncated cone, and the valve plate 9 and the sealing plate 4 are brought into contact with each other with the tapered wall surfaces, the two are closely fitted. In combination, favorable results can be obtained in ensuring airtightness.

(Second Embodiment)
2 to 4 are views showing a second embodiment of the present invention. In FIG. 2, the valve plate 9 is pressed against the sealing plate 4 through the insulating plate 14 so as to close the valve port 7 by the ridges 8, and the peripheral portion 14 a of the insulating plate 14 is in close contact with the inner periphery of the cap 5. Yes. The same material as the first embodiment can be applied to the estrus 8 and the valve body 9, and the same material as the annular insulator of the first embodiment can be applied to the insulating plate 14. 2 to 4, the insulating sheet 12 may be disposed between the inner surface of the cap 5 and the estrus 8. However, the ridge 8 and the valve body 9 are electrically insulated by the insulating plate 14. Therefore, in this embodiment, the insulating sheet 12 can be omitted.

  FIG. 3 shows a state in which energization is cut off when a predetermined internal pressure is exceeded when the battery of FIG. 2 is charged. When the internal pressure of the battery rises, the valve plate 9 moves to the position shown in FIG. 2 against the pressure of the ridge 8, and since it is separated from the sealing plate, the energization circuit is opened and charging is interrupted. At this time, airtightness is maintained by the close contact between the peripheral edge portion 14 a of the insulating plate 14 and the inner surface of the cap 5. When gas absorption progresses and the internal pressure decreases, the valve plate 9 is pushed down by the ridge 8, the circuit is closed, and the state shown in FIG.

   FIG. 4 shows a case where a sudden increase in internal pressure occurs, for example, when a large current is applied for some reason at the end of charging, and when the valve plate 9 is temporarily pushed further upward, the peripheral portion of the insulating plate 14 The lower side of 14a exceeds the position of the exhaust hole 15 of the cap 5, and the gas in the battery is discharged out of the battery system. When the internal pressure decreases, the exhaust port 51 is immediately closed, and the escape of gas is minimized.

(Third embodiment)
In FIG. 5, the peripheral edge 14 ′ a of the insulating plate 14 ′ is curved downward so as to cover the valve plate 9, and the outer surface of the peripheral edge is in close contact with the inner surface of the cap 5 due to its elasticity. The valve plate 9 closes the valve port 7 in an air-tight and liquid-tight manner by the pressure of the ridge 8, but when the internal pressure of the battery rises and the valve plate 9 is pushed up and the electric circuit is opened, the valve plate space 13 becomes a battery. The inner pressure is equal to the inside, and the peripheral edge portion 14'a is pressed outward in the radial direction to enhance the close contact with the cap 5, thereby maintaining airtightness and liquid tightness. The valve plate remains on the side of the valve plate even if the air connection is slightly impaired even after a minute foreign matter intervenes after the circuit breaks due to internal pressure rise, etc. It accumulates in the space 13 and contributes to securing airtightness as well. The peripheral edge portion 14 ′ a is also useful for fixing the position of the valve plate 9.

(Fourth embodiment)
In the embodiment of FIG. 6, the peripheral edge 14 ″ a of the insulating plate 14 ″ has a flange-like shape that can swing in close contact with the inner surface of the cap 5 ′. The peripheral portion 14 ″ a plays an important role in maintaining the airtightness of the battery as a whole, and the lower portion, that is, the portion extending toward the inside of the battery, receives the internal pressure of the battery as in the peripheral portion 11b of FIG. The other edge 14 ″ a is the posture control of the valve plate 9 and works so that the valve plate 9 moves up and down in parallel with the sealing plate 4. Therefore, the risk that the valve plate 9 is inclined when the internal pressure rises and the current cannot be cut off despite the gas escape is avoided. Moreover, it always covers the periphery of the exhaust hole 15 greatly, and helps to further maintain airtightness. If the valve plate 9 is fixed to the insulating plate 14 ″, the sealing performance is excellent when the internal pressure of the battery is below the specified value, and there is no possibility of the valve plate 9 moving when the gas escapes.

  In the lid 3 ′ of FIG. 6, the periphery of the cap 5 ′ and the battery case can 1 are crimped and the battery is sealed. In this case, when the weld between the cap 5 'and the sealing plate 4' does not maintain airtightness, the airtightness is due to the close contact between the flange-like peripheral portion 14 "a and the inner surface of the cap 5 '. Since the area is not larger than the bottom area formed by the inner surface of the cap 5 unless a special design is made, the ridge 8 is more instant at the moment when the valve port 7 is opened against the force of the ridge 8 due to an increase in internal pressure. The position of the exhaust hole should be set in consideration of this point.In the case of 16, the gas (air) remaining in the cap when the valve plate is raised Although the vent hole for discharging is shown, when the vent hole 16 is not provided, the gas pressure in the cap is increased by utilizing the fact that the pressure of the gas in the cap increases as the compressibility of the gas in the cap increases. Can have the same effect as the stalk.

  If the strip 8 in the present invention is made of metal, it can be expected to have sufficient resilience because it is much superior to a rubber-like elastic body in heat resistance and durability. Since the insulating plate does not need rubber elasticity, for example, a fluorine-containing synthetic resin that is tough and excellent in heat resistance can be used. Therefore, even if the battery is temporarily exposed to high temperatures, it does not undergo deformation or deterioration, and even if it receives a strong impact, there is no risk of damage such as movement of the valve plate. Therefore, a highly reliable sealed storage battery can be obtained. However, it does not exclude using inorganic or organic single or composite material having excellent heat resistance and rigidity.

(Example)
To an aqueous solution in which 1 part by weight of cobalt nitrate and 5 parts by weight of zinc nitrate are added to 94 parts by weight of nickel nitrate and dissolved, ammonium sulfate and an aqueous solution of sodium hydroxide are added dropwise and stirred while maintaining the pH in the range of 11 to 12, Nickel hydroxide particles in which Co and Zn were dissolved were precipitated. This was washed with water and dried to obtain nickel hydroxide powder. Subsequently, this nickel hydroxide powder was put into an aqueous solution of ammonium sulfate and sodium hydroxide, and cobalt sulfate and an aqueous sodium hydroxide solution were added dropwise thereto while stirring and controlling to pH 11-12. After holding at a predetermined pH for 1 hour, this was washed with water and dried to obtain nickel hydroxide powder coated with cobalt hydroxide. The content of cobalt hydroxide in the obtained nickel hydroxide powder was 6%. Further, after the nickel hydroxide powder coated with cobalt hydroxide was put into an aqueous sodium hydroxide solution adjusted to 14 mol / dm ³ and having a temperature of 50 ° C. and stirred, the oxidation value of nickel hydroxide was 2. The amount of K ₂ S ₂ O ₈ was calculated so as to be 10 and charged. Two hours later, this mixture was filtered, washed with water, and dried, and then 98 parts by weight of the powder was mixed with 2 parts by weight of ytterbium oxide, and an aqueous solution in which a thickener was dissolved was added to form a paste. And pressed to a predetermined thickness to obtain a positive electrode plate.

Each metal was weighed to have a composition of MmNi _3.8 Al _0.3 Co _0.7 Mn _0.2 (Mm is a mixture of Misch metal, La 30%, Ce 50%, Pr 5%, Nd 15%), using a high frequency induction melting furnace, An alloy ingot was prepared in an inert atmosphere and heat-treated at 1000 ° C. This was ground to a size of 75 μm or less to obtain a hydrogen storage alloy powder. Mixing 99.5 parts by weight with 0.5 parts by weight of ytterbium oxide, adding an aqueous solution in which a thickener is dissolved, and applying a paste made of polytetrafluoroethylene as a binder on both sides of the punching metal. After drying, it was pressed to a predetermined thickness to obtain a negative electrode plate.

60 parts by weight of a splittable composite fiber having a fineness of 3 denier, which is composite-spun so that the weight ratio of polypropylene to ethylene-vinyl alcohol copolymer is 50:50, and the fiber cross sections are alternately adjacent to each other; Using a core component and 40 parts by weight of a core-sheath composite fiber having a denier of 2 denier with polyethylene as a sheath component, wet papermaking was performed so that the basis weight was 45 g / m ² . A high-pressure water stream was jetted onto the fiber to entangle the fibers, and at the same time, the splittable composite fiber was split to obtain a non-woven fabric having a fineness of 0.2 denier after splitting. The thickness was adjusted to 0.12 mm to obtain a separator.

The positive electrode plate and the negative electrode plate having a capacity 1.2 times larger than the positive electrode capacity were prepared and wound in a spiral shape with the separator interposed therebetween to produce an electrode group. This electrode group is housed in a cylindrical metal battery case, and an electrolyte solution composed of an aqueous solution in which 7 mol / dm ³ of KOH and 1 mol / dm ³ of LiOH are dissolved is used to obtain an electrolyte solution of 1.16 cm ³ per 1 Ah of positive electrode capacity. After injecting the liquid, the lid shown in FIG. 1 was used for sealing, and an AA size, 2000 mAh nickel-metal hydride storage battery of the present invention was produced. Moreover, the nickel hydride storage battery of the comparative example which made all the same structures as the said Example except having used the sealing method based on patent document 1 was produced.

  Ten batteries each of the product of the present invention and the comparative example were left on a hot plate heated to 200 ° C. for 30 minutes. Further, another 10 pieces were dropped from the height of 100 cm onto the concrete floor three times with the cap facing down, and then the battery was subjected to an overcharge test for 60 minutes at a current of 10 A. These results are shown in Table 1.

  As shown in Table 1, it can be seen that the sealed storage battery of the present invention has no hindrance to the function of shutting off electricity or discharging gas even under a high temperature environment, or by impact or deformation of the battery drop.

  Of course, the present invention can also be applied to nickel-cadmium storage batteries. However, if applied to a nickel metal hydride storage battery, which is considered to be difficult to carry out rapid charging compared to a nickel cadmium storage battery, the effect is great.

  As a charging method of the sealed storage battery of the present invention, a method that can add a large current in the initial stage, such as a constant voltage method, can be used. After the energization circuit is shut off due to internal pressure, energization is resumed due to a decrease in internal pressure. However, a method such as reducing the current using the shut-off signal or opening the circuit after a certain number of operations is easily adopted. be able to.

  By making sealed storage batteries, especially alkaline storage batteries as described in the claims of the present invention, energy density per volume can be further improved, and charging time can be shortened by rapid charging with a large current. In addition, since heat resistance and impact resistance are improved, development of highly reliable mobile electronic devices for heavy loads can be supported.

The longitudinal cross-sectional view of the principal part of the sealed storage battery which concerns on the 1st Embodiment of this invention The longitudinal cross-sectional view of the principal part of the sealed storage battery which concerns on the 2nd Embodiment of this invention. FIG. 2 is a longitudinal cross-sectional view of the main part of the dense storage battery when the internal pressure is increased in the implementation of FIG. FIG. 2 is a longitudinal sectional view of the main part of the sealed storage battery when the internal pressure further increases in the implementation of FIG. The longitudinal cross-sectional view of the principal part of the sealed storage battery which concerns on the 3rd Embodiment of this invention. The longitudinal cross-sectional view of the principal part of the sealed storage battery which concerns on the 4th Embodiment of this invention. Longitudinal sectional view of the main parts of a conventional sealed battery

Explanation of symbols

3, 3 'Lid 4, 4' Sealing plate 5, 5 'Cap 6 Gasket 7 Valve port 8 Spring 9 Valve plate 10 Lead plate 11 Annular insulator 14, 14', 14 "Insulating plate 11a, 14a, 14'a , 14 ″ a peripheral edge 12 insulating sheet 13 valve plate space 15 exhaust hole

Claims (5)

  A battery in which a battery case can is sealed with a lid that cuts off energization when the internal pressure of the battery increases, the lid having a sealing plate and a cap, and the cap provided with an exhaust hole is joined to the sealing plate and A polar electrical terminal is formed, and the cap includes a strip that is electrically insulated at least one of the upper and lower sides and a valve plate that is in contact with the cap and has an insulating sealing member around the upper surface. The sealed battery is characterized in that the valve plate is electrically connected to the electrode of the polarity, and the valve port provided in the sealing plate is pressed and closed by the ridge.   The sealed storage battery according to claim 1, wherein a flexible insulating plate that swings in close contact with the inner periphery of the cap serves as both insulation under the splay and an insulating sealing material.   The sealed storage battery according to claim 2, wherein a flexible insulating plate normally covers and seals the exhaust hole.   4. The sealed storage battery according to claim 2, wherein the peripheral edge of the flexible insulating plate forms a peripheral edge portion that is in close contact with the inner periphery of the cap and extends vertically or downward. The sealed storage battery according to any one of claims 1 to 4, wherein the battery is a nickel metal hydride storage battery.

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