JP2004158262A - Secondary battery, charger, and secondary battery system using them - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a secondary battery system in which control of charging is easy and a secondary battery and a charger used for it. <P>SOLUTION: This battery system comprises a case 20, a group of electrode plates housed in the case 20, a sealing body 12 that seals one end of the case 20 and functions as a first electrode terminal. The case 20 comprises a terminal part 22c functioning as a second electrode terminal at another end on another side of the one end, and a diaphragm part 22a that projects reversibly according to the pressure within the case 20. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a secondary battery, a charger suitable for the secondary battery, and a secondary battery system using the same.
[0002]
[Prior art]
In a general secondary battery, a case is sealed using a sealing body provided with a safety valve (for example, see Patent Documents 1 and 2). When such a sealing plate is used, when the pressure inside the battery rises abnormally, the safety valve operates, so that the pressure inside the battery can be prevented from rising excessively.
[0003]
When such a secondary battery is rapidly charged with a large current, the internal pressure of the battery may increase sharply and the safety valve may operate. At this time, the gas and the electrolyte inside the battery are discharged from the safety valve to the outside of the battery to lower the internal pressure of the battery. On the other hand, the discharge of the gas and the electrolyte may significantly deteriorate the characteristics of the battery.
[0004]
For this reason, charging with a small current is currently the mainstream, and usually, complicated control functions such as voltage control (−ΔV control), temperature control (dT / dt control), and timer control are provided on the charger side. It is necessary to have
[0005]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 9-237620 [Patent Document 2]
JP 2000-90960 A
[Problems to be solved by the invention]
However, such a control method is complicated, and there is a demand for a method of performing quick charging by a simpler method. In addition, in the above-described conventional control method, the control corresponding to the internal pressure of the battery is not performed, so that it is necessary to perform charging with a certain margin.
[0007]
In view of such circumstances, an object of the present invention is to provide a secondary battery system in which charging can be easily controlled, and a secondary battery and a charger used for the secondary battery system.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, a secondary battery of the present invention includes a case, an electrode group housed in the case, and a sealing body that seals one end of the case and functions as a first electrode terminal. In the secondary battery provided, the case has, at the other end opposite to the one end, a terminal portion functioning as a second electrode terminal, and a plate that reversibly protrudes according to pressure in the case. It is characterized by having.
[0009]
In the above secondary battery, the sealing body may include a safety valve that operates at a predetermined operating pressure, and the plate may protrude at a predetermined pressure lower than the operating pressure.
[0010]
In the above secondary battery, the plate may be a thin metal plate.
[0011]
In the above secondary battery, the plate may include an insulating convex portion protruding toward the outside of the case at a central portion thereof.
[0012]
In the secondary battery, when the plate is not protruding, the plate is disposed inside the terminal portion, and when the plate is protruded, a part of the plate is disposed outside the terminal portion. It may be.
[0013]
Further, the charger of the present invention is a charger for charging a secondary battery, wherein the secondary battery is a secondary battery including a plate that reversibly protrudes according to the internal pressure thereof, wherein the plate The battery is charged in a state in which the battery does not protrude, and the secondary battery is not charged in a state in which the plate protrudes.
[0014]
The battery charger includes first and second terminals for applying voltage to first and second electrode terminals of the secondary battery to charge the secondary battery, wherein the plate does not protrude. In the above, the first and second terminals are connected to the first and second electrode terminals, respectively, and when the plate is protruding, the connection between the first terminal and the first electrode terminal, and At least one connection selected from the connection between the second terminal and the second electrode terminal may be disconnected.
[0015]
In the above charger, when the plate protrudes, at least one terminal selected from the first terminal and the second terminal moves by a pressing force of the plate, and the at least one connection is disconnected. Is also good.
[0016]
The charger may include a switch that is turned on when the plate is not protruding and is turned off when the plate is protruded, and the switch is used to control ON / OFF of charging.
[0017]
In the charger, charging may be performed with a constant current of 9 C or more.
[0018]
Further, a secondary battery system of the present invention is a secondary battery system using the secondary battery of the present invention and the charger of the present invention.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0020]
(Embodiment 1)
In Embodiment 1, a cylindrical secondary battery will be described as an example of the secondary battery of the present invention. However, the secondary battery of the present invention is not limited to a cylindrical battery, and may have another shape such as a prismatic shape.
[0021]
FIG. 1 shows a cross-sectional view of the secondary battery 10 of the first embodiment. Referring to FIG. 1, a secondary battery 10 includes a case 20 (hatching is omitted), an electrode group 11 and an electrolytic solution (not shown) housed in the case 20, and a sealing body 12. The sealing body 12 seals one end of the case 20 and functions as a first electrode terminal. The inside of the case 20 has a certain airtightness secured by the sealing body 12.
[0022]
The electrode group 11 is an electrode group generally used for a secondary battery, and includes a positive electrode 11a, a negative electrode 11b, and a separator 11c disposed between the positive electrode and the negative electrode. In the case of a cylindrical secondary battery, the positive electrode, the negative electrode, and the separator are usually laminated and spirally wound. The electrode group of the prismatic secondary battery may be spirally wound as in the case of the cylindrical shape, or simply laminated. The material constituting the electrode group 11 is selected according to the secondary battery to be formed. The secondary battery of the present invention is, for example, a nickel-cadmium secondary battery, a nickel-hydrogen secondary battery, or the like, but is not limited thereto, and may be a secondary battery in which the internal pressure of the battery changes during charging and discharging. It can be applied to any battery. The electrode plate group 11 can be formed by a known material and a method according to the type of the battery. For example, in the case of a nickel-hydrogen secondary battery, a positive electrode using nickel hydroxide, a negative electrode using a hydrogen storage alloy, a polyolefin nonwoven fabric (for example, a polypropylene nonwoven fabric) that has been subjected to a hydrophilic treatment can be used. In the case of a nickel-cadmium secondary battery, a positive electrode using nickel hydroxide, a negative electrode using cadmium, a polyolefin nonwoven fabric subjected to hydrophilic treatment, or the like can be used.
[0023]
A general sealing member used for a secondary battery can be applied to the sealing member 12. FIG. 1 shows, as an example, a sealing body 12 including a safety valve 12a, a positive electrode terminal plate 12b (hatching is omitted), a disk 12c (hatching is omitted), and a gasket 12d. The safety valve 12a is disposed inside a space formed by the positive electrode terminal plate 12b and the disk 12c. The safety valve 12a is formed of rubber or the like, and has a function of operating when the pressure (battery internal pressure) inside the case 20 becomes higher than a predetermined pressure (safety valve operating pressure) to reduce the battery internal pressure. The operating pressure of the safety valve is usually set to a predetermined value within a range of about 1.5 MPa to 3.0 MPa. The positive electrode terminal plate 12b is electrically connected to the positive electrode 11a and functions as a positive electrode terminal.
[0024]
A known electrolytic solution can be applied to the electrolytic solution sealed in the case 11 according to the type of the secondary battery. For example, an aqueous solution of an alkali metal salt such as potassium hydroxide or the like can be used as an electrolyte for a nickel-hydrogen secondary battery or a nickel-cadmium secondary battery.
[0025]
The case 20 includes a cylindrical portion 21 and a bottom portion 22. The cylindrical portion 21 is made of, for example, a metal (for example, metal such as iron or stainless steel) and has a cylindrical shape. One end of the case 20 is sealed by the sealing body 12. A bottom portion 22 is welded to the other end of the case 20. The cylindrical portion 21 is hermetically sealed by the sealing body 12 and the bottom portion 22.
[0026]
The bottom 22 includes a diaphragm 22a, an insulator 22b, and a terminal 22c. The diaphragm portion 22a is a plate that reversibly projects or depresses according to the internal pressure of the battery. The diaphragm portion 22a can be formed, for example, of a thin plate made of a metal such as stainless steel. The insulator 22b is made of, for example, an insulator such as a resin, and is attached to a substantially central portion of the diaphragm 22a by a rivet 22d. The terminal portion 22c has a ring shape and is arranged on the outer peripheral portion of the end of the cylindrical portion 21. The terminal portion 22c protrudes from a portion between the diaphragm portion 22a and the terminal portion 22c, and forms a step. The terminal portion 22c is electrically connected to the negative electrode and functions as a negative terminal. When the terminal portion 22c having such a step shape is used, the negative electrode side terminal of the charger can be arranged inside the concave portion, and it is possible to prevent a normal battery from being charged by the charger of the present invention. However, in the secondary battery of the present invention, the negative electrode side terminal does not have to be protruded from other portions.
[0027]
When the pressure (battery internal pressure) in the case 20 is higher than a predetermined pressure (diaphragm operating pressure), the diaphragm portion 22a of the bottom portion 22 protrudes toward the outside of the case 20, and the pressure in the case 20 is reduced to the diaphragm operating pressure. If it is lower than this, it falls down toward the inside of the case 20. The vicinity 23 of the outer peripheral portion of the bottom portion 22 may be formed of, for example, a metal plate having a thickness of about 0.6 mm, and the diaphragm portion 22a may be formed of a metal plate having a thickness of, for example, about 0.15 mm to 0.20 mm. Good. By changing these thicknesses, the diaphragm operating pressure can be controlled.
[0028]
The optimum value of the diaphragm operating pressure varies depending on the type and size of the battery, but is set to a value lower than at least the safety valve operating pressure. In the case of a nickel-hydrogen secondary battery, the diaphragm operating pressure can be set to a predetermined value within a range of, for example, 1.0 MPa to 1.5 MPa. In the case of a nickel-cadmium secondary battery, the diaphragm operating pressure can be set to a predetermined value within a range of, for example, 0.5 MPa to 1.0 MPa.
[0029]
When the diaphragm portion 22a protrudes toward the outside of the case 20, the bottom portion 22 has the insulator 22b positioned outside the terminal portion 22c. When the diaphragm portion 22a is depressed, the insulator 22b is connected to the terminal portion 22c. It is formed so that it may be located inside. However, depending on the charger, the deformation of the bottom portion 22 may not be such a deformation. For example, the case where the negative electrode side terminal of the charger is depressed, the case where the charger is provided with an ON / OFF switch, and the case where the charger is provided with a projection at a portion corresponding to the diaphragm portion 22a. The bottom part 22 may be any as long as it deforms so that charging of the charger is turned off when the diaphragm part 22a protrudes.
[0030]
In addition, the bottom part 22 is not limited to the above-described structure, and may be any as long as it protrudes / retracts according to the pressure in the case 20 and thereby enables ON / OFF control of charging. For example, the bottom 22 need not include the insulator 22b and the terminal 22c. In the above description, the case where the bottom portion 22 is welded has been described. However, when the case 20 is formed by rolling, the diaphragm portion is formed on the bottom surface of the case 20 by controlling the thickness of the bottom portion of the case 20. You may.
[0031]
(Embodiment 2)
In a second embodiment, an example of the charger and the secondary battery system of the present invention will be described. The charger of the present invention is a charger for charging the secondary battery according to the present invention described in the first embodiment. This charger performs ON / OFF control depending on the state of a plate that reversibly collapses / projects according to the internal pressure of the battery. That is, charging is stopped when the plate protrudes due to high internal pressure of the battery, and charging is performed when the plate is depressed. Hereinafter, an example of the charger of the present invention will be described.
[0032]
FIG. 2 is a plan view of the charger 30 according to the second embodiment. The charger 30 includes a first terminal 31, a second terminal 32, and a case 33. The second terminal 32 is embedded in a part of an insulating flat plate 34. The insulating flat plate 34 is fixed to the case 33 by a spring 35. As described later, the flat plate 34 and the second terminal 32 are movable.
[0033]
In the case 33, a secondary battery to be charged is arranged. A voltage is applied between the first terminal 31 and the second terminal 32 to charge the secondary battery. As a circuit for applying a voltage, a general circuit used for a charger, for example, a circuit for charging with a constant current can be applied.
[0034]
When the diaphragm portion 22a is not protruding, the first terminal 31 is connected to the positive terminal of the secondary battery, the second terminal 32 is connected to the negative terminal of the secondary battery, and the first terminal 31 and the second terminal 32 are connected to each other. A voltage is applied between the terminal 32 and the terminal 32 to charge the secondary battery. FIG. 3A is an enlarged view of the second terminal portion in this case. 3A and 3B, only the second terminal 32 is hatched.
[0035]
On the other hand, when the secondary battery is charged, the internal pressure of the battery increases. For example, when charging a nickel-metal hydride secondary battery, oxygen gas is generated inside the battery, and the internal pressure of the battery increases. The increase in the battery internal pressure becomes more remarkable as the battery is charged at a higher charging rate (current value). In the secondary battery of the present invention, when the battery internal pressure becomes equal to or higher than the diaphragm operating pressure, the diaphragm portion 22a protrudes, and the insulator 22b protrudes outside the terminal portion 22c. As a result, the flat plate 34 and the second terminal 32 move, and the connection between the terminal portion 22c and the second terminal 32 is disconnected, as shown in FIG. The repulsive force of the spring 35 is selected so that the connection between the terminal portion 22c and the second terminal 32 is disconnected when the diaphragm portion 22a protrudes.
[0036]
When the diaphragm portion 22a protrudes in this way, charging is interrupted. When charging is interrupted, the gas generated inside the battery gradually disappears, and the internal pressure of the battery decreases. When the internal pressure of the battery reaches a predetermined value lower than the operating pressure of the diaphragm 22a, the diaphragm 22a is depressed, and the terminal 22c of the secondary battery and the second terminal 32 are connected. As a result, charging of the secondary battery is started again.
[0037]
The charger of the second embodiment does not require a special circuit for controlling charging. It goes without saying that some electronic circuit may be provided for the purpose of improving safety or charging more rapidly. For example, by combining various control circuits used in a conventional charger with the charger of the present invention, rapid charging can be performed more safely.
[0038]
Fast charging is possible by combining the secondary battery of Embodiment 1 with the charger of the present invention. For example, it is possible to charge at a current value of 4C (1C is a current value that can be fully charged in one hour) or more, and it is also possible to charge at a current value of 9C or more. The current value at the time of quick charging is preferably 3C or more and 10C or less.
[0039]
Note that the charger of the present invention is not limited to the charger described above. The charger of the present invention is a secondary battery charger including a plate that reversibly protrudes according to the internal pressure of the battery, and performs charging when the plate is not protruding, and performs charging when the plate is protruding. Any charger that does not perform this operation may be used. For example, in the above description, the charger in which the second terminal 32 on the negative electrode side moves has been described, but the first terminal 31 on the positive electrode side may move. The means for moving the terminal is not limited to a spring, but may be another moving means such as a leaf spring. Further, in the above description, the charger in which the terminal is moved by the projection of the diaphragm portion 22a has been described. However, a charger having a switch that is ON / OFF controlled by the movement of the diaphragm portion 22a may be used. In this case, the terminal does not need to be moved. The switch may be a mechanical switch or a combination of a sensor that detects the movement of the diaphragm 22a and a circuit that performs ON / OFF control according to the output of the sensor.
[0040]
The secondary battery system of the present invention includes the secondary battery of Embodiment 1 and the above-described charger of the present invention. According to this secondary battery system, quick charging is possible. In addition, this secondary battery system has an advantage that it is not necessary to mount a complicated circuit on the charger. In addition, in the secondary battery system of the present invention, when charging the secondary battery, the secondary battery may be set in a dedicated battery box and charged.
[0041]
【Example】
Hereinafter, the present invention will be described in detail with reference to examples. In this example, the secondary battery 10 shown in FIG. 1 was actually manufactured. Specifically, a nickel-hydrogen secondary battery having a capacity of 1700 mAh was manufactured. In this nickel-metal hydride secondary battery, the periphery 23 of the bottom 22 was formed of stainless steel having a thickness of about 0.6 mm, and the diaphragm 22a was formed of stainless steel having a thickness of 0.15 mm to 0.20 mm. The operating pressure of the safety valve 12a was set to about 2.5 MPa, and the diaphragm operating pressure was set to about 1.0 MPa.
[0042]
The prepared battery was charged at 15 A (about 9 C) for 10 minutes using the charger of the present invention. However, during the 10 minutes, there was a time when the diaphragm portion protruded and charging was stopped. Thereafter, the battery was discharged at 1.7 A (1 C) until the battery voltage reached 0.9 V. The discharge capacity at this time was about 1250 mAh to 1350 mAh. In addition, the surface temperature of the battery after charging was about 60 ° C., and was kept at a low temperature despite charging with a large current. In addition, there was no occurrence of liquid leakage due to an increase in battery temperature and internal pressure due to charging.
[0043]
For comparison with the battery of the present invention, 10 cells of a conventional battery (standard capacity: 1700 mAh, safety valve operating pressure: about 2.5 MPa) were prepared, and the same experiment was performed. As a result, liquid leakage was confirmed in 7 cells. The discharge capacity of the three cells that did not leak showed a low value of about 800 mAh to 900 mAh. Furthermore, in the conventional battery, the surface temperature after charging has reached about 100 ° C. As described above, by using the secondary battery system of the present invention, rapid charging with a large current could be safely performed.
[0044]
As described above, the embodiments of the present invention have been described by way of examples. However, the present invention is not limited to the above embodiments, and can be applied to other embodiments based on the technical idea of the present invention.
[0045]
【The invention's effect】
As described above, the secondary battery, the charger, and the secondary battery system of the present invention enable ultra-rapid charging with a large current. Also, by providing the battery pack and the electronic device including the secondary battery with similar functions, the battery pack and the electronic device can be rapidly charged. Further, since complicated control (eg, -ΔV, dT / dt, etc.) as in the related art is not required, according to the present invention, the charger can be simplified.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating a structure of an example of a secondary battery of the present invention.
FIG. 2 is a plan view showing an example of the charger of the present invention.
FIGS. 3A and 3B are diagrams showing functions of the charger of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Secondary battery 11 Electrode group 11a Positive electrode 11b Negative electrode 11c Separator 12 Sealing body 12a Safety valve 12b Positive terminal plate 12c Disk 12d Gasket 20 Case 21 Cylindrical part 22 Bottom part 22a Diaphragm part 22b Insulator 22c Terminal part 30 Charger 31 First Terminal 32 second terminal 33 case 34 flat plate 35 spring

Claims (11)

A secondary battery including a case, an electrode group housed in the case, and a sealing body that seals one end of the case and functions as a first electrode terminal,
The case includes, at the other end opposite to the one end, a terminal portion functioning as a second electrode terminal, and a plate that reversibly protrudes according to pressure in the case. Next battery. The sealing body includes a safety valve that operates at a predetermined operating pressure,
The secondary battery according to claim 1, wherein the plate projects at a predetermined pressure lower than the operating pressure. The secondary battery according to claim 1, wherein the plate is a thin metal plate. The secondary battery according to any one of claims 1 to 3, wherein the plate includes an insulating convex portion protruding toward the outside of the case at a central portion thereof. The plate is arranged inside the terminal portion when the plate does not project, and a part of the plate is arranged outside the terminal portion when the plate projects. 5. The secondary battery according to any one of claims 1 to 4. A charger for charging a secondary battery,
The secondary battery is a secondary battery including a plate that reversibly protrudes according to its internal pressure,
In the state where the plate does not protrude, perform charging of the secondary battery,
The battery charger does not charge the secondary battery when the plate protrudes. First and second terminals for applying voltage to first and second electrode terminals of the secondary battery to charge the secondary battery,
In a state where the plate does not protrude, the first and second terminals are connected to the first and second electrode terminals, respectively,
In a state where the plate protrudes, at least one connection selected from the connection between the first terminal and the first electrode terminal and the connection between the second terminal and the second electrode terminal is disconnected. The charger according to claim 6. 8. The at least one connection according to claim 7, wherein when the plate protrudes, at least one terminal selected from the first terminal and the second terminal is moved by a pressing force of the plate, and the at least one connection is disconnected. Charger. The battery charger according to claim 6, further comprising a switch that is turned on when the plate is not protruding and is turned off when the plate is protruded, and that controls charging ON / OFF using the switch. 10. The charger according to claim 6, wherein charging is performed with a constant current of 9 C or more. A secondary battery system using the secondary battery according to any one of claims 1 to 5 and the charger according to any one of claims 6 to 10.

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