JP5105394B2 - Battery unit - Google Patents

Description

The present invention relates to batteries unit, in particular, it relates to a battery unit between the inter-cell or a single cell and another component is connected with an electrical connector.

  Conventionally, in a battery unit (battery pack) having a plurality of unit cells, an electrical connection body is used for connection between unit cells or connection between a unit cell and another part, for example, an external terminal or another battery unit. ing. This electrical connector is designed for the purpose of efficiently extracting current from the unit cell, and is not designed for any other purpose.

  In recent years, electric vehicles (EVs) and hybrid electric vehicles (HEVs) that assist electric motors with electric motors have been developed by automobile manufacturers due to global warming and fuel depletion problems. Therefore, secondary batteries with high output have been demanded. Normally, a battery unit is used as a power source for EVs and HEVs. However, in order to increase the output, the internal resistance of the secondary battery and the electrical resistance of the electrical connection body are reduced to reduce the resistance of the entire battery unit. There is a need to reduce. As a technique for achieving high output, for example, a lightweight battery lead technique in which a metal other than aluminum is disposed at both ends of a strip-shaped aluminum main body is disclosed (see Patent Document 1). ).

  On the other hand, in the battery unit, an abnormal large current may be applied due to an external short circuit or the like. In this case, since the electrical resistance of the electrical connection body is reduced, the connection member, etc. in the secondary battery may generate more heat than the electrical connection body and may melt quickly, making the secondary battery unusable. End up. In order to prevent this and protect the secondary battery, it is common to connect a fuse between single cells or between single cells and other parts. Since it is necessary to cause the fuse to be heated and blown when there is an abnormality, the electrical resistance of the fuse is set to be higher than that of each connection member except for the electrode group. Since the fuse is blown at the time of abnormality, the current is interrupted, so that each connecting member can be prevented from being damaged. In addition, there is a mechanism that connects a fuse in the secondary battery and blows it in the event of an abnormality. In this case, an instantaneous solvent may be emitted when the fuse is blown, so an organic solvent is used for the electrolyte. Employing non-aqueous secondary batteries such as lithium secondary batteries is a problem in terms of safety. In other words, as the power source for EVs and HEVs, the internal resistance of the secondary battery and the electrical resistance of the electrical connection body are reduced to increase the output, and the effect of the fuse is also obtained when energizing a large current such as an external short circuit. In other words, it is desirable to protect the secondary battery and ensure safety.

JP 2002-63878 A

  However, as described above, the battery unit is designed so as to obtain a high output. However, since the fuse is connected together with the electric connection body between the single cells and the like, the number of parts to be connected increases and it takes time and effort. In this situation, the electrical resistance of the fuse is not sufficient for high output performance. Moreover, although the electrical connection body connects between single cells etc., the height dimension of the secondary battery which comprises a battery unit is not necessarily the same, is slightly different, and has a variation in a dimension. For this reason, since stress is applied to the electrical connection body by connecting the cells with the electrical connection body, the connection state between the electrical connection body and the secondary battery or another part becomes unstable, increasing the electrical resistance. The output will be reduced.

An object of the present invention is to provide a battery unit using an electrical connection body that can stabilize a connection state and protect a unit cell in view of the above-described case.

In order to solve the above-described problems, the present invention provides a battery unit in which a single cell or a single cell and another part are connected by an electrical connection body , wherein the electrical connection body is an electrode group accommodated in the single cell. A battery lid, a positive electrode current collector ring, a negative electrode current collector ring, a negative electrode lead plate, and a battery container that are disposed between the external terminal of the single cell and that constitute the single cell, and have an electric resistance greater than that of each connection member of the battery container. In addition, a linear groove is formed over the entire length in the width direction perpendicular to the longitudinal direction at a substantially central portion in the longitudinal direction, and the thickness of the portion where the groove is formed is It is smaller than the thickness of another part, and the notch is formed in the both sides of the said groove | channel in the said width direction, It is characterized by the above-mentioned.

In the present invention , the electrical connection body is formed in a strip shape, and a linear groove is formed over the entire length in the width direction orthogonal to the longitudinal direction at a substantially central portion in the longitudinal direction. Even when connecting single cells or other parts with variations, the groove absorbs the stress applied to the electrical connection body, so that a good connection state between the single cells or between the single cells and the separate parts can be secured. A battery lid, a positive electrode current collector ring, a negative electrode current collector ring, a negative electrode lead plate and a battery container connecting member which are arranged between the electrode group housed in the battery and the external terminal of the single cell and constitute the single cell. It has a large electrical resistance, the thickness of the part where the groove is formed is smaller than the thickness of the other part, and notches are formed on both sides of the groove in the width direction. Grooves were formed when current flowed Since minute heating is blown to become large quickly as compared with the connecting member, it is possible to identify the fusing portion, the breakage of the connecting member can be prevented. Therefore, since the specific part of the electrical connector is melted at the time of abnormality, each connection member in the unit cell is protected, so that the connection state can be stabilized and the unit cell can be protected and the safety can be improved.

In this case, the cross-sectional area of the portion where the groove of the electrical connection body is formed may be reduced by pressing, stamping or cutting. Further, the length of the notch in the longitudinal direction of the electrical connection body may be made smaller than the groove . Also, it may be a rectangular battery a single battery.

According to the present invention, the electrical connection body is formed in a strip shape, and a linear groove is formed over the entire length in the width direction orthogonal to the longitudinal direction at a substantially central portion in the longitudinal direction. Even when connecting single cells or other parts having dimensional variations, it is possible to ensure a good connection between the single cells or between the single cells and the separate parts, as well as the battery lid and positive electrode current collector constituting the single cells. The ring, the negative electrode current collector ring, the negative electrode lead plate, and the battery container have an electrical resistance greater than that of each connection member, the thickness of the groove-formed portion is smaller than the thickness of the other portion, and the width of the groove in the width direction Since notches are formed on both sides, the part where the groove is formed blows out earlier than each connecting member when an abnormal large current flows, so the fusing part can be identified and each connection Can prevent damage to the parts , There can be provided an advantage.

  Hereinafter, an embodiment of a battery unit in which an electrical connection body according to the present invention is used for connecting two unit cells will be described with reference to the drawings.

(Constitution)
As shown in FIG. 1, the battery unit 1 of the present embodiment includes cylindrical lithium ion secondary batteries 30a and 30b as two unit cells. In one lithium ion secondary battery 30a, one end side in the longitudinal direction of the electrical connection body 3 made of nickel (Ni) is welded to the positive electrode external terminal. In the other lithium ion secondary battery 30b, the other end side in the longitudinal direction of the electrical connection body 3 is welded to the negative electrode external terminal. That is, the two lithium ion secondary batteries 30 are connected in series by the electrical connection body 3. The electrical connection body of the same type as that of the electrical connection body 3 is omitted from the negative electrode external terminal of the lithium ion secondary battery 30a and the positive electrode external terminal of the lithium ion secondary battery 30b. Are respectively connected to external terminals (not shown) for taking out the.

  As shown in FIG. 2, the electrical connection body 3 is formed in a strip shape, and a cut is formed at each of both ends in the longitudinal direction at approximately the center in the width direction orthogonal to the longitudinal direction. The electrical connection body 3 is formed in an arc shape on both sides in the width direction of the cuts formed on both ends in the longitudinal direction. A linear groove 5 is formed on one side of the electrical connection body 3 at a substantially central portion in the longitudinal direction over the entire length in the width direction of the electrical connection body 3. The groove 5 is formed so that the longitudinal section of the electrical connection body 3 is substantially U-shaped and orthogonal to the longitudinal direction of the electrical connection body 3. The portion of the electrical connection body 3 where the groove 5 is formed has a reduced cross-sectional area as compared with the unformed portion (other portion) of the groove 5 by pressure pressing, stamping or cutting. For this reason, in the part in which the groove | channel 5 was formed, thickness is set smaller than the non-formation part of a groove | channel. The electrical connection body 3 has an electrical resistance greater than that of each connection member described later disposed between the wound electrode group in the lithium ion secondary battery 30 and the positive and negative external terminals.

  As shown in FIG. 3, the lithium ion secondary battery 30 constituting the battery unit 1 includes a nickel-plated steel bottomed cylindrical battery container 17 and a polypropylene hollow cylindrical shaft core 11. A strip-like positive and negative electrode plate has a wound electrode group 16 wound in a spiral shape through a separator.

  On the upper side of the wound electrode group 16, an aluminum positive electrode current collecting ring 14 for collecting the electric potential from the positive electrode plate is disposed substantially on the extension line of the shaft core 11. The positive electrode current collecting ring 14 is fixed to the upper end portion of the shaft core 11. The edge part of the positive electrode lead piece 12 led out from the positive electrode plate is joined by ultrasonic welding to the peripheral edge of the collar part integrally protruding from the periphery of the positive electrode current collecting ring 14. A disc-shaped battery lid that also serves as a positive electrode external terminal is disposed above the positive electrode current collecting ring 14. The battery lid includes a lid case 22, a lid cap 23, a valve retainer 24 that keeps airtightness, and a cleavage valve 21 that cleaves when the internal pressure rises, and these are laminated to crimp the periphery of the lid case 22. Is assembled. One end of a positive electrode lead 19 formed by overlapping a plurality of aluminum ribbons is fixed to the upper portion of the positive electrode current collecting ring 14, and the other end of the positive electrode lead 19 is welded to the lower surface of the lid case 22. Each member of the positive electrode current collecting ring 14, the positive electrode lead 19, and the battery lid constitutes a positive electrode connecting member.

  On the other hand, a copper negative electrode current collecting ring 15 for collecting a potential from the negative electrode plate is disposed below the wound electrode group 16. The outer peripheral surface of the lower end portion of the shaft core 11 is fixed to the inner peripheral surface of the negative electrode current collecting ring 15. The end of the negative electrode lead piece 13 led out from the negative electrode plate is joined to the outer peripheral edge of the negative electrode current collecting ring 15 by welding. A copper negative electrode lead plate 18 for electrical conduction is welded to the lower part of the negative electrode current collecting ring 15, and the negative electrode lead plate 18 is joined to the inner bottom portion of the battery container 17 serving also as a negative electrode external terminal by welding. . Each member of the negative electrode current collecting ring 15, the negative electrode lead plate 18, and the battery container 17 constitutes a negative electrode connecting member.

The battery lid is fixed by caulking to the upper part of the battery container 17 via an insulating and heat resistant EPDM resin gasket 20. For this reason, the positive electrode lead 19 is accommodated in the battery container 17 so as to be folded, and the lithium ion secondary battery 30 is sealed. In addition, a non-aqueous electrolyte solution (not shown) that can infiltrate the entire wound electrode group 16 is injected into the battery container 17. In the non-aqueous electrolyte, 1 mol / liter of lithium hexafluorophosphate (LiPF ₆ ) as a lithium salt was dissolved in a mixed solvent of ethylene carbonate (EC) and dimethyl carbonate (DMC) in a volume ratio of 1: 2. Things are used. The lithium ion secondary battery 30 is set to a battery capacity of 15.0 Ah.

  The wound electrode group 16 is wound around the shaft core 11 via a separator made of porous polyethylene having a width of 90 mm and a thickness of 40 μm, for example, so that the positive electrode plate and the negative electrode plate are not in direct contact with each other. Has been. The positive electrode lead piece 12 and the negative electrode lead piece 13 are respectively disposed on opposite end surfaces of the wound electrode group 16. Insulation coating is applied to the entire circumference of the peripheral surface of the wound electrode group 16 and the positive electrode current collector ring 14.

  The positive electrode plate constituting the wound electrode group 16 has an aluminum foil as a positive electrode current collector, and the negative electrode plate has a rolled copper foil as a negative electrode current collector. In this example, the thicknesses of the aluminum foil and the rolled copper foil are set to 20 μm and 10 μm, respectively. Uncoated portions of the positive electrode mixture and the negative electrode mixture are formed on the side edges on one side in the longitudinal direction of the aluminum foil and the rolled copper foil, respectively. The uncoated part is cut out in a comb shape, and the positive electrode lead piece 12 and the negative electrode lead piece 13 are formed in the remaining part of the notch.

  On both surfaces of the aluminum foil, a positive electrode mixture containing lithium-containing double oxide powder as a positive electrode active material is applied substantially evenly. In the positive electrode mixture, for example, 10 parts by weight of flake graphite as a conductive material and polyvinylidene fluoride (hereinafter abbreviated as PVDF) as a binder (binder) with respect to 85 parts by weight of the positive electrode active material. 5 parts by weight is blended. When the positive electrode mixture is applied to the aluminum foil, the viscosity is adjusted with N-methylpyrrolidone (hereinafter abbreviated as NMP) as a dispersion solvent. The positive electrode plate is pressed so as to have a thickness of 100 μm after being dried, and is cut into a width of 80 mm.

  On the other hand, on both surfaces of the rolled copper foil, a negative electrode mixture containing amorphous carbon powder as a negative electrode active material is applied substantially evenly. In the negative electrode mixture, for example, 10 parts by mass of PVDF as a binder is blended with 90 parts by mass of amorphous carbon powder. When the negative electrode mixture is applied to the rolled copper foil, the viscosity is adjusted with the dispersion solvent NMP. After drying, the negative electrode plate is pressed to a thickness of 90 μm and cut to a width of 85 mm.

(Action etc.)
Next, the operation and the like of the battery unit 1 of the present embodiment will be described focusing on the operation of the electrical connection body 3 used for connection.

  Conventionally, in a battery unit having a plurality of secondary batteries (single cells), the connection between the single cells, and the connection between the single cells and another part different from the single cells such as the external terminal and another battery unit are electrically connected. A connection is used. As shown in FIG. 8, the electrical connection body 40 is a strip-shaped flat plate, and a cut is formed at each of the longitudinal ends at substantially the center in the width direction. In order to obtain high output as a battery unit, the internal resistance of the unit cell and the electrical resistance of the electrical connection body 40 are reduced. However, when an abnormally large current flows due to an external short circuit or the like, the heat generated by the connection members in the unit cell becomes larger than that of the electrical connection body 40, and the connection member etc. melts faster than the electrical connection unit 40, resulting in the unit cell. It may become unusable. For this reason, by connecting a fuse having a larger electrical resistance than each connection member except for the electrode group in the unit cell, between the unit cells and between the unit cells and other parts, each connection member The prevention of breakage is made. When such a fuse is connected, the number of parts to be connected increases, which takes time for manufacturing, and the high output performance cannot be sufficiently exhibited by the electrical resistance of the fuse. In addition, there is a case where a fuse is connected in the unit cell, but since an instantaneous spark may be generated when the fuse is blown, a non-aqueous secondary battery such as a lithium ion secondary battery is problematic in terms of safety. Become. In addition, the height of the cells constituting the battery unit is not necessarily the same, but varies, and stress is applied to the electrical connection by connecting the cells, etc., so the connection state is unstable. Thus, the electrical resistance is increased and the output is reduced. The present embodiment is a battery unit using an electrical connector that can solve these problems.

  In this embodiment, the electrical connection body 3 has a larger resistance than each connection member except the wound electrode group 16 in the lithium ion secondary batteries 30a and 30b. For this reason, when an abnormal large current such as an external short circuit flows, the electrical connection body 3 generates more heat than the connection members and melts out early. Thereby, since an abnormal large current is interrupted, disconnection (breakage) of each connection member in the battery can be prevented, and the lithium ion secondary batteries 30a and 30b can be protected. Therefore, the electrical connection body 3 secures a normal energization path, and the electrical connection body 3 also exhibits the same effect as a fuse in the event of an abnormality, so that the safety of the lithium ion secondary batteries 30a and 30b can be improved. it can.

  Moreover, in this embodiment, the electrical connection body 3 is formed with a linear groove 5 over the entire length in the width direction at a substantially central portion in the longitudinal direction. In the portion of the electrical connection body 3 where the groove 5 is formed, the cross-sectional area in the width direction is set smaller than the unformed portion of the groove, and the thickness is set smaller than the unformed portion of the groove. For this reason, when an abnormal large current flows, the heat generation in the portion where the groove 5 is formed becomes larger than that in the portion where the groove is not formed. Thereby, since the part in which the groove 5 is formed melts in the electrical connection body 3, it is possible to specify the melted part at the time of abnormality (always melt the part in which the groove 5 is formed), and the lithium ion secondary Safety measures for the battery 30 can be facilitated.

  Further, in the present embodiment, the cross-sectional area of the portion where the groove 5 is formed is reduced by pressing, stamping or cutting. Since these methods can reduce the cross-sectional area with high accuracy, it is possible to improve the reproducibility of the normal energization current value and the current value when an abnormal large current flows and the elapsed time until disconnection. .

  Furthermore, in the present embodiment, since the groove 5 is formed in the electrical connection body 3, an effect of absorbing stress (a function of buffering) in the longitudinal direction can be obtained. That is, in the electrical connection body 3, even if it is used for connection between two lithium ion secondary batteries having variations in height, the groove 5 absorbs stress applied to the electrical connection body 3. A state can be secured. Thereby, since the increase in the electrical resistance in a connection part is suppressed, an output fall can be suppressed. In addition, the portion where the groove 5 is formed is set to have a smaller cross-sectional area than the other portions of the electrical connector 3. For this reason, in the electrical connection body 3 in which the groove | channel 5 was formed, the effect which specifies the fusing location at the time of abnormality mentioned above simultaneously with the effect which absorbs stress can be exhibited.

  In this embodiment, the example in which the groove 5 having a substantially U-shaped cross section is formed in the electrical connection body 3 is shown. However, the present invention is not limited to this, and the cross-sectional shape of the groove is an arc (arch). ) Shape, V-shape or the like. For example, as shown in FIG. 4, a groove 5 having a circular arc shape in cross section may be formed at a substantially central portion in the longitudinal direction of the electrical connector 3. In the present embodiment, an example in which one groove 5 is formed is shown, but two or more grooves 5 may be formed. For example, if two arc-shaped grooves 5 shown in FIG. 4 are formed side by side, a groove having a corrugated cross section is formed. Furthermore, in this embodiment, although the example which forms the groove | channel 5 in the single side | surface of the electrical connection body 3 was shown, the cross-sectionally U-shaped groove | channel 5 shown in FIG. Thus, a groove having an H-shaped cross section is formed. In the present embodiment, the thickness of the portion where the groove 5 is formed is smaller than the thickness of the portion where the groove 5 is not formed. However, the present invention is not limited to this, and the formation of the groove 5 is performed. A portion of the thickness may be reduced in thickness. For example, in the arc-shaped groove 5 shown in FIG. 4, the thickness of only the bottom portion of the groove 5 may be reduced, and the thickness on the side surface side of the groove 5 may be the same as the unformed portion of the groove 5.

  Moreover, in this embodiment, although the groove | channel 5 formed over the whole length of the width direction of the electrical connection body 3 was illustrated, this invention is not limited to this, A notch is formed in the both sides of the groove | channel 5 You may make it do. For example, as shown in FIG. 5A, the length in the longitudinal direction of the electrical connection body 3 is the groove 5 on both sides of the substantially U-shaped groove 5 formed in the substantially central part of the electrical connection body 3. The same notch 7 may be formed. Further, as shown in FIG. 5B, the notch 7 may be formed so as to include the groove 5. That is, the length of the notch 7 in the longitudinal direction of the electrical connection body 3 may be larger than the groove 5. Further, as shown in FIG. 5C, the notch 7 may be formed in a part of the groove 5, and in this case, the length of the notch 7 is smaller than that of the groove 5. By forming such a notch 7, the cross-sectional area of the portion where the groove 5 is formed becomes smaller than the unformed portion of the groove 5, so that the groove where both sides are notched when an abnormal large current flows Since the heat generation at the portion where 5 is formed becomes larger than the other portions, the fusing portion can be reliably identified. Furthermore, such a notch 7 can also be applied to the electrical connector 3 in which the groove 5 having a circular arc cross section is formed. For example, as shown in FIG. 6 (A), notches 7 having the same length in the longitudinal direction of the electrical connection body 3 as the groove 5 may be formed on both sides of the groove 5 having an arc cross section. As shown in B), a notch 7 whose length in the longitudinal direction of the electrical connection body 3 is larger than the groove 5 may be formed.

  Furthermore, in this embodiment, although the groove | channel 5 covering the whole length of the width direction of the electrical connection body 3 was formed so that it might orthogonally cross with respect to the longitudinal direction of the electrical connection body 3, this invention showed this. It is not limited. As shown in FIG. 7A, instead of the groove 5 orthogonal to the longitudinal direction of the electrical connection body 3, as shown in FIG. The groove 5 may be formed as described above. In this case, of course, the notches 7 may be formed on both sides of the groove 5.

  Furthermore, in the present embodiment, an example in which the electrical connection body 3 is made of nickel has been shown. However, the present invention is not limited to this, and is disposed between the electrode group in the unit cell and the external terminal. What is necessary is just a thing with an electrical resistance larger than each made connection member. In the battery unit 1, since aluminum or copper is used as the material of each connection member of the lithium ion secondary batteries 30a, 30b, the material of the electrical connection body 3 is nickel. What is necessary is just to select the material of the electrical connection body 3 with the material of these.

  Furthermore, in this embodiment, although the example which connects the two lithium ion secondary batteries 30 to the battery unit 1 was shown, this invention is not restrict | limited to this. In the battery unit 1, at least two unit cells may be connected, for example, three lithium ion secondary batteries 30 may be connected. The electrical connector 3 may be used when connecting the cells in series or in parallel. A plurality of battery units 1 may be connected, and the electrical connection body 3 can be used for the connection.

  In the present embodiment, the cylindrical lithium ion secondary batteries 30a and 30b having a battery capacity of 15.0 Ah are exemplified as the single batteries constituting the battery unit 1. However, the present invention is the shape, size, battery capacity, etc. of the single batteries. It is not limited to. For example, a square battery may be used, and instead of the wound electrode group 16 in which the positive and negative electrodes are wound, an electrode group in which positive and negative electrodes are stacked may be used. Moreover, it can also be used for batteries other than lithium ion secondary batteries in general.

  Furthermore, in the present embodiment, lithium-containing double oxide and amorphous carbon are exemplified as the positive electrode active material and the negative electrode active material of the lithium ion secondary batteries 30a and 30b, respectively, but the present invention is not limited to this. Alternatively, a positive electrode active material and a negative electrode active material generally used for lithium ion secondary batteries can be used. For example, the positive electrode active material may be a double oxide containing lithium, and the negative electrode active material may be a carbon material such as graphite instead of amorphous carbon.

  Furthermore, in the present embodiment, PVDF is exemplified as the binder, but the present invention is not limited to this. For example, polytetrafluoroethylene (PTFE), polyethylene, polystyrene, polybutadiene, butyl rubber, nitrile rubber, Even if polymers such as styrene / butadiene rubber, polysulfide rubber, nitrocellulose, cyanoethyl cellulose, various latexes, acrylonitrile, vinyl fluoride, vinylidene fluoride, propylene fluoride, chloroprene, and mixtures thereof are used. Good.

Furthermore, in the present embodiment, an example was shown in which LiPF ₆ was dissolved in a mixed solvent of EC and DMC in a nonaqueous electrolytic solution. However, a general lithium salt was used as an electrolyte, and this was dissolved in an organic solvent. A non-aqueous electrolyte 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 battery unit 1 manufactured according to the present embodiment will be described. In addition, it describes together about the battery unit of the comparative example produced for the comparison. In addition, the electrical connectors used in the battery units of the examples and comparative examples can be energized for 30 seconds or more at a current value of 200 A, which exceeds the maximum current value of 100 A assumed for HEV batteries that require high output. Have confirmed.

  About the lithium ion secondary battery 30a, 30b and the electrical connection body 3, the direct current resistance of each connection member was measured with the following method. That is, using a DC power supply, energize with a current value of 5A, 10A, 15A, measure the voltage value between the fixed points of the energization path of each connecting member, plot the measured voltage value and the energized current value, It calculated | required with the least squares method, and the value was made into DC resistance. As a result, the DC resistance of each connecting member is 0.04 mΩ from the position where the electrical connection body 3 on the upper surface of the lid cap 13 is welded to the position where the positive electrode lead 19 is welded on the lower surface of the lid case 12 (that is, the battery lid). The distance between both ends of the positive electrode lead 19 is 0.08 mΩ, the distance between the welded portion of the positive electrode lead 19 of the positive electrode current collecting ring 14 to a fixed point on the outer periphery of the positive electrode current collecting ring 14 (that is, the positive electrode current collecting ring 14) is 0.05 mΩ, The distance from the fixed point on the outer periphery of the negative electrode current collecting ring 15 to the welded portion of the negative electrode lead plate 18 (that is, the negative electrode current collecting ring 15) is 0.01 mΩ, and from the welded portion of the negative electrode current collecting ring 15 on the negative electrode lead plate 18 to the battery container. The electrical connection body 3 from the welded portion (inner bottom surface) of the negative electrode lead plate 18 of the battery container 17 to the outer bottom surface of the battery container 17 is 0.07 mΩ. Between the parts to be welded (that is, the battery container 17) was 0.05 mΩ.

<Example 1>
In Example 1, an electrical connection made of Ni in which a groove 5 having a substantially U-shaped cross section is formed by thinning the thickness so as to have a cross-sectional area smaller than the cross-sectional area of the other part at the center in the longitudinal direction. Body 3 was used (see FIG. 2). The electrical connection body 3 was set to a thickness of 0.5 mm (a thickness where the groove 5 was formed was 0.4 mm), a width of 20 mm, and a length of 60 mm (a length of the groove 5 of 10 mm). The electrical connection body 3 had a resistance of 0.36 mΩ between the welded portions with the lithium ion secondary batteries 30a and 30b on both ends in the longitudinal direction. For this reason, the electrical resistance of the electrical connection body 3 is larger than each connection member of positive and negative electrodes excluding the wound electrode group 16 in the lithium ion secondary batteries 30a and 30b.

<Example 2>
In Example 2, the electrical connector 3 made of Ni in which the thickness is reduced by pressing so that the central portion in the longitudinal direction is smaller than the cross-sectional area of the other portion and the arch-shaped groove 5 is formed is used. Except this, the procedure was the same as that in Example 1 (see FIG. 4). The electrical connection body 3 was set to a thickness of 0.5 mm (a thickness of the portion where the groove 5 was formed 0.4 mm), a width of 20 mm, and a length of 60 mm (a length of the groove 5 of 2 mm). The electrical connection body 3 has a resistance between the welded portions of the lithium ion secondary batteries 30a and 30b on both ends in the longitudinal direction of 0.35 mΩ, which is larger than each connection member in the lithium ion secondary batteries 30a and 30b. Has resistance.

<Example 3>
The third embodiment is the same as the first embodiment except that the Ni electrical connector 3 in which the groove 5 having a smaller cross-sectional area than other portions is formed in the central portion and the notches 7 are formed on both sides of the groove 5 is used. (See FIG. 5A). The electrical connector 3 is set to have a thickness of 0.5 mm (thickness of the portion where the groove 5 is formed 0.4 mm), a width of 20 mm (a width of the groove 5 of 10 mm), and a length of 60 mm (a length of the groove 5 of 10 mm). did. This electrical connection body 3 has a resistance between welded portions with the lithium ion secondary batteries 30a and 30b on both ends in the longitudinal direction of 0.40 mΩ, which is larger than each connection member in the lithium ion secondary batteries 30a and 30b. Has resistance.

<Comparative Example 1>
Comparative Example 1 was the same as Example 1 except that a Ni electrical connector (see FIG. 8) having a thickness of 3 mm, a width of 20 mm, and a length of 60 mm was used. This electrical connector has a resistance of 0.06 mΩ between the welded portions with the lithium ion secondary batteries 30a and 30b on both ends in the longitudinal direction, and has a battery lid, a positive current collecting ring 14, a negative current collecting ring 15 and a battery container. It has a resistance larger than the resistance of 17 and smaller than the resistance of the positive electrode lead 19 and the negative electrode lead plate 18.

<Test and evaluation>
An external short-circuit test was carried out on each of the five battery units of each of the examples and comparative examples that were produced, and the number of breaks, breakage locations, and cell states in the electrical connector and the lithium ion secondary battery were examined. The test results are shown in Table 1 below.

  As shown in Table 1, in the battery unit of Comparative Example 1 using the conventional electrical connection body, all the five battery units tested may break in the lithium ion secondary batteries 30a and 30b which are single cells. Admitted. With regard to the ruptured part, breakage of the positive electrode lead was observed in three unit cells, and breakage of the negative electrode lead plate was observed in two unit cells. Moreover, in the battery unit of the comparative example 1, even in the state of the unit cell, the ignition was recognized by the three unit cells, and it became impossible to charge / discharge with the two unit cells. Therefore, it was found that when an external short circuit occurs in the battery unit of Comparative Example 1, the lithium ion secondary batteries 30a and 30b are not protected and safety cannot be ensured.

  On the other hand, each battery unit of Example 1-Example 3 which uses the electrical connection body 3 which has an electrical resistance larger than each connection member in the lithium ion secondary battery 30a, 30b and in which the groove | channel 5 was formed. In 1, the electrical connecting members 3 were melted in all the five batteries without causing the connecting members to break. In Examples 1 to 3, the lithium ion secondary batteries 30a and 30b used in the battery unit 1 did not ignite or rupture, and the charge / discharge performance after the test was good. From this, it was found that the battery unit 1 using the electrical connection body 3 can protect each single cell even when an external short circuit occurs, and is excellent in safety. Moreover, it was recognized that all the broken portions were portions where the grooves 5 were formed in the electrical connection body 3. From this, by making the cross-sectional area of the portion where the groove 5 is formed smaller than the other portions, the portion where the groove 5 is formed breaks at the time of an external short circuit, and therefore the break position can be specified in advance. It was found to be excellent in safety improvement. Therefore, in the battery unit 1 using the electrical connection body 3, normal large current energization (for example, in the HEV power supply, energization at a large current value assumed at the time of starting the vehicle) is possible, and an external short circuit is possible. In the unsafe state (state where an abnormally large current flows), the same effect as the fuse is obtained, and it has been found that it is excellent in safety and economy.

  The present invention provides an electrical connection body that can stabilize a connection state and protect a single cell and a battery unit using the electrical connection body, and thus contributes to the manufacture and sale of the electrical connection body and the battery unit. With the availability of

It is a perspective view of the battery unit of embodiment which used the electrical connection body concerning this invention for the connection between batteries. It is a perspective view of the electrical connection body used with the battery unit of the embodiment. It is sectional drawing of the cylindrical lithium ion secondary battery which comprises the battery unit of embodiment. It is a perspective view of the electrical connection body of another embodiment which concerns on this invention. It is a perspective view of the electrical connection body by which the notch was formed in the both sides of a groove | channel, (A) is the electrical connection body by which the length of the notch in the longitudinal direction of an electrical connection body was set to the same as a groove | channel, (B) Represents an electrical connector having a notch length larger than the groove, and (C) represents an electrical connector having a notch length smaller than the groove. It is a perspective view of the electrical connection body of another embodiment in which the notch was formed in the both sides of a groove | channel, (A) is the electrical connection by which the length of the notch in the longitudinal direction of the electrical connection body was set to the same as a groove | channel The body, (B), shows an electrical connection body in which the length of the notch is larger than the groove. It is a top view which shows the position of the groove | channel formed in the electrical connection body, (A) is a groove | channel formed so as to be orthogonal to the longitudinal direction of an electrical connection body, (B) is formed so that it may skew in a longitudinal direction. Each groove is shown. It is a perspective view of the conventional electrical connection body used with the battery unit of the comparative example.

Explanation of symbols

1 Battery unit 3 Electrical connection body 5 Groove 6 Winding electrode group (electrode group)
7 Notch 30 Cylindrical lithium ion secondary battery (single cell)

Claims (4)

In cell unit between the inter-cell or a single cell and a separate part is connected in an electrical connector, said electrical connector is coordination between the external terminals of the unit cells and the single stowed electrode group in the battery The battery lid, the positive electrode current collector ring, the negative electrode current collector ring, the negative electrode lead plate, and the battery container that constitute the unit cell have an electrical resistance larger than that of each connection member, are formed in a strip shape, and have a longitudinal direction. A linear groove is formed over the entire length in the width direction orthogonal to the longitudinal direction at a substantially central portion, the thickness of the portion where the groove is formed is smaller than the thickness of the other portion, and the width A battery unit, wherein notches are formed on both sides of the groove in the direction . 2. The battery unit according to claim 1, wherein a cross-sectional area of the portion where the groove is formed is reduced by pressure pressing, stamping, or cutting. The battery unit according to claim 1, wherein a length of the notch in the longitudinal direction is smaller than the groove. The battery unit according to any one of claims 1 to 3, wherein the single battery is a square battery .

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