JP2005108503A - Lithium secondary battery - Google Patents

Lithium secondary battery Download PDF

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Publication number
JP2005108503A
JP2005108503A JP2003337364A JP2003337364A JP2005108503A JP 2005108503 A JP2005108503 A JP 2005108503A JP 2003337364 A JP2003337364 A JP 2003337364A JP 2003337364 A JP2003337364 A JP 2003337364A JP 2005108503 A JP2005108503 A JP 2005108503A
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Japan
Prior art keywords
battery
current
pressure
lithium
cutoff valve
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
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JP2003337364A
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Japanese (ja)
Inventor
Takenori Ishizu
Akira Kojima
亮 小島
竹規 石津
Original Assignee
Shin Kobe Electric Mach Co Ltd
新神戸電機株式会社
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Application filed by Shin Kobe Electric Mach Co Ltd, 新神戸電機株式会社 filed Critical Shin Kobe Electric Mach Co Ltd
Priority to JP2003337364A priority Critical patent/JP2005108503A/en
Publication of JP2005108503A publication Critical patent/JP2005108503A/en
Abandoned legal-status Critical Current

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    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02TCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00Road transport of goods or passengers
    • Y02T10/60Other road transportation technologies with climate change mitigation effect
    • Y02T10/62Hybrid vehicles

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lithium secondary battery having excellent safety by cutting off current when the internal pressure of the battery is held at a low value even in gas generation upon battery abnormality. <P>SOLUTION: This sealed lithium secondary battery has, on a battery cover 11, a current cutoff mechanism for cutting off current when the internal pressure of the battery reaches cutoff pressure, and an opening 11a and a cleavage slot 12b for releasing the battery internal pressure when the battery internal pressure reaches cleavage pressure larger than the cutoff pressure. The current cutoff mechanism is composed of a current cutoff valve 12, a connection plate 13 connected to a wound group, and a junction part 17 for them, and the junction part 17 between the cutoff valve 12 and the connection plate 13 is cut out. A plate spring 19 having repulsive force and an insulating bushing 15 are disposed between the cutoff valve 12 and the connection plate 13. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention provides a current cutoff mechanism that shuts off a conductive path by releasing a contact between a current cutoff valve and a connecting member connected to a power generation element when the battery internal pressure reaches a predetermined cutoff pressure, and the battery internal pressure is cut off. The present invention relates to a sealed lithium secondary battery having a cleavage mechanism that releases a battery internal pressure when a cleavage pressure larger than the pressure is reached.

  Conventionally, sealed batteries have been widely used in home appliances, and recently, lithium secondary batteries have been used in particular, among sealed batteries. In addition, since lithium secondary batteries have high energy density, they are being developed as in-vehicle power sources for electric vehicles (EV) and hybrid vehicles (HEV).

  However, when the sealed battery is overcharged due to, for example, a failure of the charging device, the internal pressure of the battery may extremely increase. For this reason, a sealed battery having an explosion-proof mechanism has been proposed in which a protruding portion in which a central portion of a thin metal plate protrudes downward is welded to a thick metal plate, and the peripheral portion of these metal plates is fixed by caulking. (For example, refer to Patent Document 1). In particular, in a non-aqueous electrolyte type sealed lithium secondary battery using an organic solvent as an electrolytic solution, the battery performance is increased and the battery capacity can be increased. Therefore, a more reliable explosion-proof mechanism is required.

Japanese Patent Laid-Open No. 8-7866

  However, in the explosion-proof mechanism of the above-mentioned patent document, since the thin metal plate is substantially planar, if the electrolyte decomposes and gas is generated and the internal pressure of the battery rises at the time of abnormal battery such as overcharge, The electrical connection with the metal plate is cut off and the charging current is cut off.However, when the gas inside the battery contracts due to temperature changes, etc., the contact between the thin plate metal plate and the thick plate metal plate is again caused by the spring back of the thin plate metal plate. There is a problem that (electrical connection) occurs and an overcharge current flows. In addition, the thickness of the thin metal plate is desirably thick from the viewpoint of current capacity, but if the thickness of the thick metal plate is larger than that of the thin metal plate, the thin metal plate is the first when the internal pressure increases. Since it breaks and dissipates the gas, the junction between the thin metal plate and the thick metal plate may not be completely separated, and the current may not be interrupted. Furthermore, in the structure in which the thin metal plate and the thick metal plate are in contact with each other, a large load is applied to the thin metal plate when the upper lid is caulked and fixed at the time of battery assembly, so that the cleavage groove formed in the thin metal plate is easily cleaved. There is a problem.

  In addition, in a square battery, since the pressure resistance of the caulking fixing portion with respect to the battery internal pressure is lower than that of the cylindrical battery, when the battery cover area increases, the thin plate connection plate and the thick plate connection plate Since gas leakage may occur from the caulking fixing part at a pressure lower than the pressure at which the electrical connection of the battery is cut, the battery tends to become larger or the energy density per unit volume of the battery tends to decrease when attempting to secure a withstand voltage It is in.

  An object of the present invention is to provide a lithium secondary battery excellent in safety capable of interrupting current at a lower battery internal pressure when the battery is abnormal in view of the above-mentioned case.

  In order to solve the above-mentioned problem, the present invention releases the contact of the current shut-off valve with the connecting member connected to the power generating element when the battery internal pressure reaches a predetermined shut-off pressure greater than atmospheric pressure. A sealed lithium secondary battery comprising: a current interruption mechanism that interrupts a conductive path at a battery; and a cleavage mechanism that releases the battery internal pressure when the battery internal pressure reaches a cleavage pressure greater than the interruption pressure. A repulsive material having a repulsive force is disposed between the valve and the connecting member.

  Usually, since the plate thickness is standardized, the plate thickness used for the current cutoff valve also depends on the standard. For this reason, the cutoff pressure for releasing the contact between the current cutoff valve and the connection member (the battery internal pressure when the contact between the current cutoff valve and the connection member is released) is stepwise. In the present invention, a repulsive material having a repulsive force is arranged between the current cutoff valve and the connecting member. Therefore, by adjusting the repulsive force of the repellent material or selecting a repelling member, the cutoff pressure is reduced to the low pressure side. It is possible to set in detail.

  In the present invention, if the repulsion member is an insulator, once the current cut-off valve is released from contact with the connection member and the conductive path is cut off, the current cut-off valve is again connected by the repulsion force of the repulsion member of the insulator. Therefore, it is possible to prevent a current during an abnormal battery such as an overcharge current from flowing again between the current cutoff valve and the connecting member. In addition, the current cutoff valve has a reversible curved shape, and if the contact with the connecting member is released by reversing with the cutoff pressure, the current cutoff valve will be shut off when the battery internal pressure increases. It can be configured to maintain a non-reversal shape until the pressure is reached and to reverse when the shut-off pressure is exceeded, and since the shut-off pressure is greater than atmospheric pressure, the current shut-off valve is once reversed by the battery internal pressure when the battery is abnormal. For example, even if the inside of the battery is evacuated, the current cutoff valve does not return to its original non-inverted shape at atmospheric pressure, so the contact release state between the current cutoff valve and the connection member (the conductive path cutoff state) is maintained. be able to. Furthermore, when the lithium secondary battery is a square battery with a lower pressure resistance of the caulking fixing portion relative to the internal pressure than the cylindrical battery, the repulsive force of the repulsive material is adjusted so that the current cutoff valve is disconnected from the connection member. The pressure can be adjusted to a pressure smaller than the pressure resistance of the caulking fixing portion.

  According to the present invention, since the repulsive material having a repulsive force is disposed between the current cutoff valve and the connection member, the contact between the current cutoff valve and the connection member is released by adjusting or selecting the repulsive material. Since the cut-off pressure to be set can be finely set on the low-pressure side, the current can be cut off at a lower battery internal pressure, and the safety of the lithium secondary battery can be improved.

  Embodiments in which the present invention is applied to a cylindrical lithium secondary battery will be described below with reference to the drawings.

<Positive electrode>
Lithium manganese complex oxide powder as a positive electrode active material, scaly graphite as a conductive material, and polyvinylidene fluoride (PVDF) as a binder are mixed at a weight ratio of 85: 10: 5, and this is mixed with N as a dispersion solvent. -A slurry in which methylpyrrolidone (NMP) was added and kneaded was applied to both surfaces of an aluminum foil having a thickness of 20 µm. Thereafter, drying, pressing, and cutting were performed to obtain a positive electrode having a thickness of 170 μm. Note that one side of the aluminum stay in the longitudinal direction was cut out in a rectangular shape, and the remainder of the cutout was used as a positive electrode lead piece.

<Negative electrode>
To 90 parts by mass of the amorphous carbon powder as the negative electrode active material, 10 parts by mass of PVDF as the binder is added to the negative electrode active material, and a slurry obtained by adding and kneading the dispersion solvent NMP is added to a 10 μm thick slurry. It apply | coated to both surfaces of the electrolytic copper foil. Thereafter, a negative electrode having a thickness of 130 μm was obtained by dry pressing and cutting. Note that one side in the longitudinal direction of the electrolytic copper foil was cut out in a rectangular shape, and the remainder of the cutout was used as a negative electrode lead piece.

<Production of battery>
As shown in FIG. 1, the produced positive and negative electrodes were wound together with a polyethylene microporous separator having a thickness of 40 μm so that these two electrodes were not in direct contact with each other, thereby producing a wound group 6 as a power generation element. A hollow cylindrical shaft core made of polypropylene was used at the center of winding. At this time, the positive electrode lead piece and the negative electrode lead piece were respectively positioned on the opposite end surfaces of the wound group 6.

  The positive electrode lead pieces are deformed, and all of them are gathered and brought into contact with the vicinity of the flange peripheral surface integrally protruding from the periphery of the positive electrode current collecting ring 4, and then the positive electrode lead piece and the peripheral surface of the flange are ultrasonically welded. The positive electrode lead piece was connected to the circumferential surface of the buttock. On the other hand, the connection operation between the negative electrode current collection ring 5 and the negative electrode lead piece was performed in the same manner as the connection operation between the positive electrode current collection ring 4 and the positive electrode lead piece. Thereafter, an insulating coating was applied to the entire circumference of the collar peripheral surface of the positive electrode current collecting ring 4, and the wound group 6 was inserted into a nickel-plated steel battery container 7.

  A negative electrode lead plate 8 for electrical continuity is welded to the negative electrode current collecting ring 5 in advance. After inserting the wound group 6 into the battery container 7, the bottom of the battery container 7 and the negative electrode lead plate 8 are welded. did. On the other hand, the positive electrode current collecting ring 4 is welded with a positive electrode lead 9 formed by previously superposing a plurality of aluminum ribbons, and a battery for sealing the battery container 7 at the other end of the positive electrode lead 9. It welded to the lower surface of the lid | cover 10 (the splitter 18 mentioned later).

A predetermined amount of non-aqueous electrolyte that can infiltrate the entire wound group 6 is injected into the battery container 7, and then the battery container 7 is covered with the battery cover 10 so that the positive electrode lead 9 is folded. The battery lid 10 was caulked and fixed to the battery container 7 via a gasket to complete a sealed cylindrical lithium ion secondary battery 20 having a capacity of 9.0 Ah. As the non-aqueous electrolyte, lithium hexafluorophosphate (LiPF) was added to a mixed solution in which ethylene carbonate (EC), dimethyl carbonate (DMC), and diethyl carbonate (DEC) were mixed at a volume ratio of 1: 1: 1. 6 ) 1 mol / liter dissolved was used.

  Here, the battery lid 10 will be described in detail. As shown in FIG. 2, the battery lid 10 has a disk-like lid cap 11 made of iron and plated with nickel. A cylindrical projection that protrudes upward is formed at the center of the lid cap 11. In the vicinity of the rising surface of the protrusion, a plurality of openings 11a that can discharge the gas in the lithium ion secondary battery 20 are formed. The peripheral edge of the lid cap 11 is caulked and fixed to the peripheral edge of the current cutoff valve 12.

  The current cutoff valve 12 is made of an aluminum alloy having a thickness of 0.5 mm and has a shape curved downward in a dish shape. Between the central portion 12a and the peripheral portion of the current cutoff valve 12, a cleavage groove 12b is formed which is thinned and is cleaved when the battery internal pressure reaches a predetermined pressure (cleavage pressure). Therefore, in this embodiment, the cleavage mechanism that releases the battery internal pressure is configured by the cleavage groove 12 b and the opening 11 a of the lid cap 11. The central portion 12a of the current cutoff valve 12 is planar. The central portion 12a and the upper surface of the central portion 13a protruding in a flat shape at the center of the connecting plate 13 as a connecting member made of an aluminum alloy having a hat shape and a thickness of 0.4 mm are electrically and mechanically bonded by resistance welding. Are joined (contacted) (hereinafter, this resistance welded portion is referred to as a joint portion 17). Therefore, in the present embodiment, the current cutoff mechanism is configured by the current cutoff valve 12 (central portion 12a), the connection plate 13 (central portion 13a), and the joint portion 17.

  Between the current cutoff valve 12 and the peripheral portion of the connection plate 13, a repulsive material made of an electrically insulating resin such as polypropylene, an annular bush 15 as an insulator, and an annular stainless steel having a thickness of 0.2 mm. The splitter 14 is clamped via a leaf spring 19 as a repulsive material. In the present embodiment, the clearance formed by the current cutoff valve 12 and the splitter 14 is set to about 0.3 mm. The bush 15 and the leaf spring 19 have a force acting in a direction to disconnect the connection between the current cutoff valve 12 and the connection plate 13 (open the contact between the two). The splitter 14 is an annular plate made of aluminum alloy, and a plurality of through holes 14a are formed at the center of the ring. The peripheral portion of the splitter 14 is locked by a splitter locking ring 16 having a substantially T-shaped cross section that abuts the peripheral flat portion of the current cutoff valve 12 and separates the splitter 14 from the current cutoff valve 12. The splitter locking ring 16 has a flange portion on the inner peripheral surface side. The flange portion abuts on the splitter 14 and is attached to the positive electrode current collecting ring 4 via an annular spacer 18 (see FIG. 1). Supported from below. The current cutoff valve 12 is connected to the positive electrode of the wound group 6 via the connection plate 13, the splitter 14, and the positive electrode current collecting ring 4 via the joint portion 17.

  Further, in the battery lid 10, the thickness T1 of the central portion 12a of the current cutoff valve 12 is set larger than the thickness T2 of the central portion 13a of the connection plate 13, and the thickness T2 of the central portion 13a of the connection plate 13 is The current cutoff valve 12 is set to be larger than 1/3 of the thickness T1 of the central portion 12a (T1> T2> 1/3 · T1). Further, the tensile strength S1 of the material of the current cutoff valve 12 is set larger than the tensile strength S2 of the material of the connection plate 13 (S1> S2).

  Next, the operation and the like of the lithium secondary battery 20 of the present embodiment will be described.

  Since the lithium secondary battery 20 is set to have a thickness T2 of the central portion 13a of the connection plate 13 larger than 1/3 of a thickness T1 of the central portion 12a of the current cutoff valve 12, it is in a normal state (other than an abnormal battery state). In this state, the necessary current capacity from the connection plate 13 to the lid cap 11 via the current cutoff valve 12 can be ensured. For this reason, the temperature rise of the connecting plate 13 due to insufficient current capacity can be suppressed.

  On the other hand, when the lithium secondary battery 20 falls into a battery abnormal state such as overcharge, the nonaqueous electrolyte is decomposed and gas is generated in the battery container 7 at an accelerated rate. Although the internal pressure of the battery is increased by this gas, the current cutoff valve 12 is connected to the connection plate 13 up to a predetermined pressure (shutoff pressure, for example, 0.5 to 2.5 MPa) determined by the shape, dimensions, material, etc. of the current cutoff valve 12. Maintain the bonding. The current cutoff valve 12 maintains a dish-like shape up to the cutoff pressure. When the battery internal pressure exceeds the cutoff pressure, the current cutoff valve 12 instantly disconnects the connection with the connection plate 13. When a reversible diaphragm is used for the current cut-off valve 12, the non-reversed shape is maintained up to the cut-off pressure, and when the battery internal pressure exceeds the cut-off pressure, the diaphragm reverses and separates the joint. At this time, the thickness T1 of the central portion 12a of the current cutoff valve 12 is larger than the thickness T2 of the central portion 13a of the connection plate 13, and the connection plate 13 of the joint portion 17 is broken first. Will never open.

  Once the current cutoff valve 12 is disconnected from the connection plate 13, the central portion 12 a of the current cutoff valve 12 mechanically contacts the central portion 13 a of the connection plate 13 again by a leaf spring 19 having a repulsive force. There is nothing. Furthermore, even if the current cutoff valve 12 contacts the leaf spring 19, the current cutoff valve 12 and the connection plate 13 do not come into electrical contact if the bush 15 is an insulator as described above. Further, when a diaphragm is used for the current cutoff valve 12, the predetermined pressure at which the diaphragm is reversed is larger than the atmospheric pressure. Therefore, once the current cutoff valve 12 is reversed, the atmospheric pressure is maintained even if the battery container 7 is evacuated. Thus, the current cutoff valve 12 does not return to its original shape, and the broken central portion 13a of the connecting plate 13 does not come into electrical contact with the central portion 12a of the current cutoff valve 12 again. For this reason, the current can be completely interrupted, and a battery excellent in safety can be obtained. Furthermore, since the tensile strength S1 of the material of the current cutoff valve 12 is made larger than the tensile strength S2 of the material of the connection plate 13, the central portion 13a of the joint portion 17 is surely broken first to interrupt the current. , Safety is ensured.

  Further, in the lithium secondary battery 20 of the present embodiment, a force is applied in the direction in which the leaf spring 19 and the bush 15 separate the junction between the current cutoff valve 12 and the connection plate 13. For this reason, for example, since the leaf spring 19 does not have a repulsive force, the joint portion 17 can be broken at a lower pressure than the predetermined pressure determined by the shape, dimensional material, and the like of the current cutoff valve 12. Therefore, it is possible to obtain a lithium secondary battery that is excellent in securing the resistance.

  When the battery internal pressure further rises, the current cutoff valve 12 is formed with a thinned cleavage groove 12b. This cleavage groove 12b is cleaved by the internal pressure, and the gas in the battery container 7 is formed in the splitter 14. It is discharged to the outside through the through hole 14a, the cleavage location of the cleavage groove 12b, and the opening 11a formed in the lid cap 11. Therefore, the lithium secondary battery 20 can be safely guided to an unusable state. At this time, the peripheral portion of the splitter 14 is locked to the plane of the current cutoff valve 12 by the splitter locking ring 16, so that the current cutoff valve 12 is not damaged by the splitter 14. For this reason, the gas is released from the damaged part due to the damage of the current cutoff valve 12, and the breakage of the current cutoff valve 12 and the connection plate 13 is prevented, or the gas is released outside from the cleavage groove 12b after inversion. Can be prevented.

  In the present embodiment, the cylindrical lithium secondary battery is exemplified, but the present invention is not limited to the cylindrical type, and may be applied to, for example, a rectangular battery. In particular, in the case of a caulking structure prismatic battery in which the area of the battery lid has been increased due to the increase in size of the battery, the cutting pressure (breaking pressure) between the current cut-off valve 12 and the connection plate 13 is higher than the pressure resistance of the caulking fixing portion. There is a problem that deformation of the caulking fixing part occurs before current interruption and current interruption cannot be performed and current safety cannot be ensured. However, in this embodiment, by adjusting the repulsive force of the leaf spring 19, Since the cutting pressure between the current cutoff valve 12 and the connection plate 13 can be adjusted to a pressure lower than the pressure resistance of the fixed portion, it is effective for ensuring safety.

  Further, in the present embodiment, an example in which an aluminum alloy is used as the material of the current cutoff valve 12, the connection plate 13, and the splitter 14 is shown, but the present invention is not limited to this, for example, aluminum, nickel alloy, Other conductive materials such as conductive plastic may be used.

  Furthermore, in this embodiment, although the example using the annular splitter locking ring 16 was shown, the shape of the splitter locking ring 16 is not restricted to an annular shape, For example, a semi-annular member is used. A plurality of splitters may be locked using a plurality.

  Moreover, in this embodiment, although the example which gave the repulsive force and the insulation to the leaf | plate spring 19 and the bush 15, respectively was shown, as shown in FIG. 3, it is set as the material and / or shape which have a repulsive force on the bush 15. As shown in FIG. Thus, it is possible to use a material to which repulsive force and insulating properties are simultaneously provided. If such an aspect is taken, the number of parts can be reduced, and thus the cost of the lithium secondary battery 20 can be reduced. Further, in the present embodiment, an example in which stainless steel is used for the plate spring 19 is shown, but the present invention is not limited to this, and any material that functions as a plate spring such as aluminum, aluminum alloy, nickel alloy, or the like. Can be used. Further, in the present embodiment, the leaf spring is exemplified as the repulsive material, but any shape having a repulsive force such as a spiral spring (coil spring) can be applied to the present invention without being limited to the material and shape.

  In the present embodiment, as shown in FIG. 2, the bush 15 is exemplified by polypropylene as a material. However, the present invention is not limited to this, and for example, EPDM resin can be used. Any material and / or shape having a repulsive force can be used.

  Further, in this embodiment, lithium manganese double oxide is exemplified as the positive electrode active material, but it can be applied if a lithium metal double oxide in which a sufficient amount of lithium is inserted in advance is used, and Al, The present invention is also applicable to the case where a lithium metal double oxide in which a part of a metal is substituted or doped with a metal element such as Co, Cr, Fe, or Ni is used.

  In this embodiment, PVDF is exemplified as the binder, but polytetrafluoroethylene (PTFE), polyethylene, polystyrene, polybutadiene, butyl rubber, nitrile rubber, styrene / butadiene rubber, polysulfide rubber, nitrocellulose, cyanoethylcellulose, various types Polymers such as latex, acrylonitrile, vinyl fluoride, vinylidene fluoride, propylene fluoride, chloroprene fluoride, and mixtures thereof may be used.

Furthermore, in the present embodiment, a nonaqueous electrolytic solution in which LiPF 6 is dissolved in a mixed solution of EC, DEC, and DMC is exemplified. However, a nonaqueous electrolytic solution in which a general lithium salt is used as an electrolyte and this is dissolved in an organic solvent. A liquid may be used, and the present invention is not particularly limited to the lithium salt or organic solvent used. For example, as the electrolyte, LiClO 4 , LiAsF 6 , LiBF 4 , LiB (C 6 H 5 ) 4 , CH 3 SO 3 Li, CF 3 SO 3 Li, or a mixture thereof can be used. Examples of the organic solvent include propylene carbonate, ethylene carbonate, 1,2-dimethoxyethane, 1,2-diethoxyethane, γ-butyrolactone, tetrahydrofuran, 1,3-dioxolane, 4-methyl-1,3-dioxolane, Diethyl ether, sulfolane, methyl sulfolane, acetonitrile, propiontonyl, etc., or a mixed solvent of two or more of these may be used, and the mixing ratio is not limited.

  Next, examples of the cylindrical lithium ion battery 20 manufactured according to the above-described embodiment will be described. In addition, it describes together about the battery of the comparative example produced for the comparison.

<Example 1>
In Example 1, a battery 20 was manufactured using a polypropylene material having a leaf spring 19 thickness of 0.2 mm and a bush 15 having a thickness of 0.1 mm (see FIG. 2).

<Example 2>
In Example 2, a battery was manufactured in the same manner as in Example 1 except that a polypropylene material having a thickness of 0.25 mm for the leaf spring 19 and a thickness of 0.05 mm was used for the bush 15 (see FIG. 2). .

<Example 3>
In Example 3, the leaf cover 19 was not used, and the battery lid 10 was produced using an EPDM resin material having a thickness of 0.4 mm for the bush 15, and the battery was the same as in Example 1 except for the structure of the battery lid 10. (See FIG. 3).

<Example 4>
In Example 4, the leaf spring 19 is not used, and the battery lid 10 is produced using an EPDM resin material having a thickness of 0.5 mm for the bush 15, and the battery is the same as in Example 1 except for the structure of the battery lid 10. (See FIG. 3).

<Example 5>
In the fifth embodiment, the current cutoff valve 12 is a diaphragm, and the battery lid 10 is manufactured using an EPDM resin material having a thickness of 0.4 mm for the bush 15. The battery similar to that of the first embodiment except for the structure of the battery lid 10 is used. Was produced (see FIG. 4).

<Comparative Example 1>
In Comparative Example 1, the battery lid 10 was produced without using the leaf spring 19 and the bush 15 shown in FIG. 2, and a battery was produced in the same manner as in Example 1 except for the structure of the battery lid 10.

<Comparative example 2>
In Comparative Example 2, a battery lid 10 was produced without using the bush 15 shown in FIG. 4, and a battery was produced in the same manner as in Example 1 except that the structure of the battery lid 10 and the current cutoff valve 12 were made diaphragms.

<Test and evaluation>
The following test was implemented about each battery cover and battery of the Example and comparative example which were produced as mentioned above. The battery lid 10 was assumed to increase the internal pressure of the battery, and was pressurized only from the lower surface of the battery lid 10, and the cutting pressures at the central portion 12 a of the current cutoff valve 12 and the central portion 13 a of the connection plate 13 were measured. In order to confirm the cutting, the resistance between the lid cap 11 and the connection plate 13 was measured, and the pressure that became 9999 MΩ or more was defined as the cutting pressure. Thereafter, the insulation between the current cutoff valve 12 and the connection plate 13 when the pressure from the lower surface of the battery lid 10 was removed and the pressure was returned to normal pressure was also confirmed. In addition, each battery produced was charged at a current value of 9 A, and then intentionally overcharged at 9 A, the current interruption state was examined, and the total amount of charge until the current interruption was calculated. The test results are shown in Table 1 below.

  As shown in Table 1, compared to the batteries of Comparative Examples 1 and 2, by providing a material having a repulsive force between the current cutoff valve 12 and the connection plate 13 as in the batteries of Examples 1 to 5, the current The shut-off valve 12 and the connection plate 13 could be cut at a lower pressure. Moreover, if the material which has repulsive force like the battery of Examples 3-5 is an insulator, a number of parts can be reduced and cost reduction can be aimed at. It was also found that the current cutoff valve has a curved shape, and that the insulation is improved by using a diaphragm that cuts off the current by reversing it. Moreover, in the overcharge test, the current of the battery of the example was interrupted in a state where the total charge amount was smaller than that of the battery of the comparative example, and it was confirmed that safety was improved.

  The lithium secondary battery according to the present invention is a battery excellent in safety, and has a large industrial value for a lithium secondary battery in which the safety tends to decrease as the battery capacity increases.

It is sectional drawing of the lithium ion battery of embodiment which can apply this invention. It is sectional drawing of the battery cover which can be used for the lithium secondary battery of embodiment. It is sectional drawing of the other battery cover which can be used for the lithium secondary battery of embodiment. It is sectional drawing of another battery cover which can be used for the lithium secondary battery of embodiment.

Explanation of symbols

6 Winding group (power generation element)
10 Battery cover (upper cover)
11a Opening (part of cleavage mechanism)
12 Current cutoff valve 12b Cleavage groove (part of cleavage mechanism)
13 Connection plate (connection member)
15 Bush (part of the repulsion member)
19 Leaf spring (part of the repulsion member)
20 Cylindrical lithium ion battery (lithium secondary battery)

Claims (4)

  1.   A current shut-off mechanism that shuts off the conductive path by releasing the contact between the current shut-off valve and the connection member connected to the power generation element when the battery internal pressure reaches a predetermined shut-off pressure greater than atmospheric pressure, and the battery; A sealed lithium secondary battery having a cleavage mechanism for releasing the battery internal pressure when an internal pressure reaches a cleavage pressure larger than the cutoff pressure, wherein a repulsive force is generated between the current cutoff valve and the connection member. A lithium secondary battery, characterized by disposing a repulsive material.
  2.   The lithium secondary battery according to claim 1, wherein the repulsive material is an insulator.
  3.   2. The lithium secondary battery according to claim 1, wherein the current cutoff valve has a reversible curved shape and releases contact with the connection member by being reversed by the cutoff pressure.
  4.   The lithium secondary battery according to any one of claims 1 to 3, wherein the lithium secondary battery is a prismatic battery.
JP2003337364A 2003-09-29 2003-09-29 Lithium secondary battery Abandoned JP2005108503A (en)

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010101179A1 (en) 2009-03-03 2010-09-10 株式会社Nttファシリティーズ Lithium-ion battery
US8546005B2 (en) 2008-12-23 2013-10-01 Samsung Sdi Co., Ltd. Cap assembly and secondary battery having the same
KR101330612B1 (en) 2007-08-27 2013-11-18 삼성에스디아이 주식회사 Rechargeabel battery
US8936861B2 (en) 2008-11-06 2015-01-20 Toyota Jidosha Kabushiki Kaisha Sealed battery
JP2015130359A (en) * 2015-03-16 2015-07-16 株式会社豊田自動織機 Power storage device comprising current breaking device
WO2016194571A1 (en) * 2015-05-29 2016-12-08 株式会社豊田自動織機 Current shut-off device and electricity storage device equipped therewith

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101330612B1 (en) 2007-08-27 2013-11-18 삼성에스디아이 주식회사 Rechargeabel battery
US8936861B2 (en) 2008-11-06 2015-01-20 Toyota Jidosha Kabushiki Kaisha Sealed battery
US8546005B2 (en) 2008-12-23 2013-10-01 Samsung Sdi Co., Ltd. Cap assembly and secondary battery having the same
WO2010101179A1 (en) 2009-03-03 2010-09-10 株式会社Nttファシリティーズ Lithium-ion battery
JP2015130359A (en) * 2015-03-16 2015-07-16 株式会社豊田自動織機 Power storage device comprising current breaking device
WO2016194571A1 (en) * 2015-05-29 2016-12-08 株式会社豊田自動織機 Current shut-off device and electricity storage device equipped therewith
JPWO2016194571A1 (en) * 2015-05-29 2018-03-01 株式会社豊田自動織機 Current interrupt device and power storage device including the same
US10361422B2 (en) 2015-05-29 2019-07-23 Kabushiki Kaisha Toyota Jidoshokki Current interruption device and electricity storage device including the same

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