JP2019135695A - Sealed battery - Google Patents

Abstract

To propose a current interruption mechanism capable of more securely performing interruption.SOLUTION: A current interruption mechanism 17 comprises: a pair of ends 17a, 17b made by dividing a negative electrode side conduction path 16; an elastic body 17c for applying force so as to enlarge a distance between the pair of ends 17a, 17b; an interval holding part 17d put across the pair of ends 17a, 17b to hold the distance between the pair of ends 17a, 17b; an electric wire 17e that is put across the pair of ends 17a, 17b and is connected to the pair of ends 17a, 17b; a resistance heating element 17f attached to the interval holding part 17d; and a switching part 17g configured to detect an electric potential difference between a positive electrode side conduction path 14 and the negative electrode side conduction path 16 and output current to the resistance heating element 17f when an electric potential difference higher than a predetermined electric potential difference is detected. When the interval holding part 17d is melted down by the resistance heating element 17f, the negative electrode side conduction path 16 is disconnected.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a sealed battery.

Japanese Patent Laying-Open No. 2015-60658 discloses a secondary battery provided with a current interrupting unit that is melted during overcharging and interrupts current as a device for preventing overcharging.
The current interrupting unit proposed in the same publication interrupts a passing current when a current exceeding a predetermined threshold flows. One of the current interrupting units is connected to the positive terminal and the other is connected to the positive short-circuit lead. The current interrupting unit melts when the current flowing through the current interrupting unit exceeds a predetermined threshold, and interrupts the current flowing through the positive electrode short-circuit lead. For example, the current interrupting unit is assumed to be a fuse or the like.

  Japanese Patent Application Laid-Open No. 2013-157154 includes an additive that is electrolyzed during overcharge to generate gas. Then, gas is generated in the case of the sealed battery during overcharge, and the internal pressure in the case of the sealed battery is increased. And the mechanism which interrupts | blocks an electric current is proposed because the internal pressure in the case of a sealed battery becomes high.

Japanese Patent Laying-Open No. 2015-60658 JP2013-157154A

  By the way, it is desirable that the current interrupting unit as a device for preventing overcharge is not interrupted by the normal current but is surely interrupted when overcharge is detected. In the structure disclosed in Japanese Patent Application Laid-Open No. 2015-60658, it is difficult to set the current interrupting unit so that it is not interrupted by normal current and is reliably interrupted when overcharge is detected.

  For example, in applications used as a drive source for electric vehicles such as plug-in hybrid vehicles and electric vehicles, high capacity is required for sealed batteries such as lithium ion secondary batteries. As the capacity increases, the amount of active material contained in the battery case increases. For this reason, the amount of gas that can be generated even during normal charging and discharging tends to increase. Furthermore, if space saving in a battery case is achieved, dead space will decrease. For this reason, a very small amount of gas that can be generated by normal charging and discharging is gradually accumulated, and the internal pressure of the battery case tends to increase. Therefore, the present inventor believes that, along with the increase in capacity, the battery case of the sealed battery requires a relief valve in addition to the safety valve. However, if the relief valve is provided, the internal pressure of the battery case can be kept at a constant level, and thus the current interrupting mechanism that operates due to the increased pressure in the battery case becomes difficult to operate.

One embodiment of the sealed battery proposed here includes an electrode body having a positive electrode current collector and a negative electrode current collector, a battery case containing the electrode body, a positive electrode terminal attached to the battery case, a positive electrode A positive-side conduction path connecting the current collector and the positive terminal, a negative terminal attached to the battery case, a negative-side conduction path connecting the negative current collector and the negative terminal, a positive-side conduction path and the negative side A current interruption mechanism that is provided in any one of the first conduction paths and that interrupts the first conduction path.
The current interruption mechanism includes a pair of end portions where the first conduction path is divided, an elastic body that applies a force so as to increase a distance between the pair of end portions, and a pair of end portions. A distance holding part that holds the distance, a wire that spans between the pair of end parts and is joined to the pair of end parts, a resistance heating element attached to the distance holding part, a positive-side conduction path and a negative-side conduction And a switching unit configured to detect a potential difference from the path and output a current to the resistance heating element when there is a potential difference higher than a predetermined potential difference.
Here, the space | interval holding | maintenance part is good to be comprised so that it may be melted | fused when a resistance heating element generates heat. Moreover, the 1st conduction | electrical_connection path | route connected with the electric wire is good to be comprised so that it may be disconnected, when a space | interval holding | maintenance part is blown and the distance of a pair of edge part is expanded.

  As described above, in this sealed battery, the interval holding unit is configured to be blown when the resistance heating element generates heat. And the 1st conduction | electrical_connection path | route connected by the electric wire is comprised so that a space | interval holding | maintenance part may be cut off, and it may be disconnected when the distance of a pair of edge part is expanded. For this reason, energization to the battery is surely interrupted by overcharge.

FIG. 1 is a schematic diagram of a sealed battery 10. FIG. 2 is an enlarged view of the current interrupt mechanism 17. FIG. 3 is an enlarged view of the current interrupt mechanism 17. FIG. 4 is an enlarged view of the current interrupt mechanism 17 in another embodiment.

  Hereinafter, an embodiment of the sealed battery proposed here will be described. The embodiments described herein are, of course, not intended to limit the present invention in particular. The invention is not limited to the embodiments described herein unless specifically stated. Each drawing is drawn schematically and does not necessarily reflect the real thing. Each drawing shows only an example and does not limit the present invention unless otherwise specified. Moreover, the same code | symbol is attached | subjected suitably to the member and site | part which show | plays the same effect | action, and the overlapping description is abbreviate | omitted.

FIG. 1 is a schematic diagram of a sealed battery 10.
As shown in FIG. 1, the sealed battery 10 includes an electrode body 11, a battery case 12, a positive electrode terminal 13, a positive electrode side conduction path 14, a negative electrode terminal 15, a negative electrode side conduction path 16, A current interruption mechanism 17.

  The electrode body 11 has a positive electrode current collector 11a and a negative electrode current collector 11b. The electrode body 11 is a so-called battery element. In addition, the specific form of the electrode body 11 is not limited to the form illustrated here unless it is specifically limited. The sealed battery 10 may be an all-solid battery including a solid electrolyte, for example. The electrode body 11 may be used for an all-solid battery.

  Although detailed illustration is omitted, the electrode body 11 may be a so-called laminated electrode body in which a positive electrode sheet and a negative electrode sheet are stacked with a separator sheet interposed therebetween, for example. Moreover, as another form of the electrode body 11, a positive electrode sheet, a 1st separator sheet, a negative electrode sheet, and a 2nd separator sheet are each used as an elongate strip | belt-shaped member. The electrode body 11 may be a so-called wound electrode body obtained by winding a positive electrode sheet and a negative electrode sheet with a long strip-shaped first separator sheet or second separator sheet interposed therebetween.

  In the positive electrode sheet, for example, a positive electrode active material layer containing a positive electrode active material is formed on a positive electrode current collector foil (for example, an aluminum foil) except for an unformed portion set at a certain width at one end in the width direction. It is good to be formed on both sides. The non-formed part where the positive electrode active material layer is not formed on the positive electrode current collector foil can be the positive electrode current collector part 11 a of the electrode body 11. For example, in a lithium ion secondary battery, the positive electrode active material is a material capable of releasing lithium ions during charging and absorbing lithium ions during discharging, such as a lithium transition metal composite material. Various positive electrode active materials are generally proposed besides lithium transition metal composite materials, and are not particularly limited.

  In the negative electrode sheet, a negative electrode active material layer containing a negative electrode active material is formed on both sides of a negative electrode current collector foil (for example, copper foil) except for an unformed part set at a certain width on one edge in the width direction. It is good to be. The non-formed part where the negative electrode active material layer is not formed on the negative electrode current collector foil can be the negative electrode current collector part 11 b of the electrode body 11. For example, in the case of a lithium ion secondary battery, the negative electrode active material is a material that can occlude lithium ions during charging and release lithium ions occluded during charging, such as natural graphite. Various negative electrode active materials are generally proposed besides natural graphite, and are not particularly limited.

As the separator sheet, for example, a porous resin sheet through which an electrolyte having required heat resistance can pass is used. Various separator sheets have been proposed and are not particularly limited. The negative electrode active material layer of the negative electrode sheet may cover the positive electrode active material layer of the positive electrode sheet with a separator sheet interposed. The separator sheet may further cover the positive electrode active material layer of the positive electrode sheet and the negative electrode active material layer of the negative electrode sheet.
The non-formed part as the positive electrode current collector 11a and the non-formed part as the negative electrode current collector 11b are directed to opposite sides in the width direction. And the non-formation part as the positive electrode current collection part 11a protrudes in the one side of the width direction of a separator sheet. The non-formed part as the negative electrode current collector part 11b protrudes from the separator sheet on the opposite side in the width direction.

  An electrode body 11 is accommodated in the battery case 12. The battery case 12 is schematically indicated by a two-dot chain line in FIG. The battery case 12 may be, for example, a flat square aluminum case.

The positive terminal 13 is an electrode terminal attached to the battery case 12.
The positive electrode side conduction path 14 is a conduction path that connects the positive electrode current collector 11 a and the positive electrode terminal 13. Here, for the positive electrode side conduction path 14, for example, a metal such as aluminum or an aluminum alloy is used.

The negative electrode terminal 15 is an electrode terminal attached to the battery case 12.
The negative electrode side conduction path 16 is a conduction path that connects the negative electrode current collector 11 b and the negative electrode terminal 15. Here, for the negative electrode side conduction path 16, for example, a metal such as copper or a copper alloy is used.
Outside the battery case 12, the positive terminal 13 and the negative terminal 15 are connected to the external power source G1 and the output device via the power control unit P1.

The current interruption mechanism 17 is provided in any one of the first conduction path 16 of the positive electrode side conduction path 14 and the negative electrode side conduction path 16, and is a mechanism that blocks the first conduction path 16.
In this embodiment, the negative electrode side conduction path 16 is set as the “first conduction path”.

FIG. 2 is an enlarged view of the current interrupt mechanism 17.
As shown in FIGS. 1 and 2, the current interruption mechanism 17 includes a pair of end portions 17a and 17b, an elastic body 17c, a spacing holding portion 17d, an electric wire 17e, a resistance heating element 17f, and a switching unit. 17g.

  The pair of end portions 17a and 17b are divided at the portion where the current interruption mechanism 17 is provided as the negative conduction path 16 as the first conduction path, and at the end of the divided negative conduction path 16. is there. Here, the pair of end portions 17a and 17b do not need to be the end portions where the members constituting the negative electrode side conduction path 16 are actually cut. The negative electrode side conduction path 16 may include a first negative electrode side conduction path 16a including the first end portion 17a and a second negative electrode side conduction path 16b including the second end portion 17b. The first end portion 17a provided in the first negative electrode side conduction path 16a and the second end portion 17b provided in the second negative electrode side conduction path 16b are provided at a portion where the current interruption mechanism 17 is provided. It is good to face each other.

  The elastic body 17c is a member that exerts a force to increase the distance between the pair of end portions 17a and 17b of the negative electrode side conduction path 16 as the first conduction path. In this embodiment, as shown in FIG. 1, the coil spring is arranged between the pair of end portions 17a and 17b in a compressed state. In this embodiment, a metal spring such as stainless steel (SUS) coated with heat-resistant resin or ceramic is used for the elastic body 17c. That is, the elastic body 17 c interposed between the pair of end portions 17 a and 17 b of the negative electrode side conduction path 16 does not conduct the pair of end portions 17 a and 17 b of the negative electrode side conduction path 16. In addition, the elastic body 17c should just be arrange | positioned so that force may be applied so that the distance of a pair of edge part 17a, 17b may be extended, It is not limited to this form. The elastic body 17c is a spring made of metal such as stainless steel (SUS), and an insulating sheet such as resin or ceramic may be sandwiched between the pair of end portions 17a and 17b and the spring. The elastic body 17c is not limited to a coiled spring, and may be rubber.

  The space | interval holding | maintenance part 17d is a member which spans a pair of edge part 17a, 17b, and hold | maintains the distance of a pair of edge part 17a, 17b. In this embodiment, the space | interval holding | maintenance part 17d is a member of predetermined length. The distance between the pair of end portions 17a and 17b of the negative electrode side conduction path 16 as the first path is predetermined at both ends of the interval holding part 17d. Since the gap holding portion 17d is attached to the pair of end portions 17a and 17b of the negative electrode side conduction path 16, the pair of end portions 17a and 17b of the negative electrode side conduction path 16 is maintained at a predetermined distance. Is done. In other words, the interval holding portion 17d may have a required rigidity capable of maintaining a predetermined distance against the elastic reaction force of the elastic body 17c. Here, the interval holding portion 17d is preferably made of a metal or a resin having a low melting point that can be melted when a current is passed through a resistance heating element 17f, which will be described later, and the resistance heating element 17f generates heat.

  The electric wire 17e is spanned over a pair of edge part 17a, 17b, and is joined to a pair of edge part 17a, 17b. In the form shown in FIG. 2, the electric wire 17e includes a first electric wire 17e1 and a second electric wire 17e2. In addition, the 1st electric wire 17e1 and the 2nd electric wire 17e2 are good to be comprised with the metal wire and tape which have electroconductivity, respectively. In FIG. 2, an example in which the electric wire 17e is configured by the first electric wire 17e1 and the second electric wire 17e2 is illustrated, but may be further connected by a plurality of electric wires. The electric wire 17e is good to be a little longer than the distance of a pair of edge part 17a, 17b of the negative electrode side conduction | electrical_connection path | route 16 maintained by the space | interval holding | maintenance part 17d. The 1st electric wire 17e1 and the 2nd electric wire 17e2 which comprise the electric wire 17e, and a pair of edge part 17a, 17b are good to be joined by the technique which can be conduct | electrically_connected. Further, the bonding strength between the first electric wire 17e1 and the second electric wire 17e2 and the pair of end portions 17a and 17b is not set so strong.

  When the space holding portion 17d is melted and a force is applied by the elastic body 17c so as to increase the distance between the pair of end portions 17a and 17b, the first electric wire 17e1 and the second electric wire 17e2 and the pair of end portions 17a and 17a, It is good to be comprised so that joining with 17b may remove | deviate. The first electric wire 17e1 and the second electric wire 17e2 constituting the electric wire 17e may be joined to the pair of end portions 17a and 17b by, for example, a technique such as wire bonding.

  The resistance heating element 17f is a heating element attached to the interval holding portion 17d. The resistance heating element 17f may be configured by a heating wire such as a nichrome wire, for example. And it is good to wind around the space | interval holding | maintenance part 17d. Here, the first end portion 17f1 of the heating wire as the resistance heating element 17f wound around the spacing holding portion 17d is preferably connected to the negative electrode side conduction path 16. In the form shown in FIG. 2, the second end portion 17 b on the negative electrode terminal side of the negative electrode side conduction path 16 is joined.

Further, the second end portion 17f2 of the heating wire as the resistance heating element 17f is preferably connected to the output terminal of the switching portion 17g as shown in FIG.
The switching unit 17g is configured to detect a potential difference between the positive electrode side conduction path 14 and the negative electrode side conduction path 16 and output a current to the resistance heating element when there is a potential difference higher than a predetermined potential difference. Yes.

Here, the switching part 17g is good to be comprised by the electronic circuit containing the Zener diode or Zener diode comprised, for example so that a predetermined overcharge voltage might be detected. The switching unit 17g is connected to the positive-side conduction path 14 by the first input line 17g1. The switching unit 17g is connected to the negative electrode side conduction path 16 by the first input line 17g2. Further, the output-side terminal of the switching unit 17g is connected to the positive-side conduction path 14 and the resistance heating element 17f.
The switching unit 17 g detects a voltage based on a potential difference between the positive electrode side conduction path 14 and the negative electrode side conduction path 16. When the voltage detected based on the potential difference between the positive electrode side conduction path 14 and the negative electrode side conduction path 16 is lower than a predetermined overcharge voltage, the switching unit 17g The resistance heating element 17f is insulated. When the voltage detected by the switching unit 17g becomes equal to or higher than a predetermined overcharge voltage, the positive-side conduction path 14 and the resistance heating element 17f are conducted.

  The voltage detected based on the potential difference between the positive electrode side conduction path 14 and the negative electrode side conduction path 16 becomes equal to or higher than a predetermined overcharge voltage when the sealed battery 10 is connected to the external power supply G1. This is the case when it is charged. For this reason, when the positive electrode side conduction path 14 and the resistance heating element 17f are conducted by the switching part 17g, a circuit of the external power source G1, the positive electrode side conduction path 14, the switching part 17g, the resistance heating element 17f, and the negative electrode side conduction path 16 is formed. Is done. Therefore, with the external power supply G1 as a power source, a current flows through the resistance heating element 17f, and the resistance heating element 17f generates heat.

  In this sealed battery 10, as shown in FIGS. 1 and 2, when the voltage detected by the switching unit 17g is equal to or higher than a predetermined overcharge voltage, the positive-side conduction path 14 and the resistance heating element 17f And the resistance heating element 17f generates heat. When the resistance heating element 17f generates heat, the interval holding portion 17d is melted.

Here, FIG. 3 is an enlarged view of the current interrupt mechanism 17. In FIG. 3, the resistance heating element 17f is not shown.
As shown in FIG. 3, when the distance holding portion 17d is fused, the distance between the pair of end portions 17a and 17b is increased. At this time, the negative electrode side conduction path 16 as the first conduction path connected by the electric wire 17e is disconnected. Moreover, the electric wire 17e is good to be comprised by the some electric wire 17e1, 17e2 as mentioned above. And after the space | interval holding | maintenance part 17d is cut off, it is good to be comprised so that it may fracture | rupture sequentially.

FIG. 3 shows a state in which the gap holding portion 17d is melted and the first electric wire 17e1 and the second end portion 17b of the negative electrode side conduction path 16 are disconnected from the electric wire 17e. Thereafter, the second electric wire 17e2 and the second end 17b are further disconnected from each other, and the negative electrode side conduction path 16 is disconnected. Moreover, when the electric wire 17e is further comprised by the some electric wire, all the electric wires are fractured | ruptured sequentially.
The elastic body 17c may be configured to increase the distance between the pair of end portions 17a and 17b until the negative electrode side conduction path 16 is disconnected by disconnection of the electric wire 17e. When the voltage detected by the switching unit 17g decreases after being disconnected, the energization to the heating wire is stopped.

FIG. 4 is an enlarged view of the current interrupt mechanism 17 in another embodiment. Here, the same reference numerals are given to members or parts having the same functions as those in FIG.
As shown in FIG. 4, a second elastic body 17h may be provided in the second negative electrode side conduction path 16b including the second end portion 17b.
Here, the second negative electrode side conduction path 16b including the second end portion 17b includes the second negative electrode side conduction path 16b1 on the side including the second end portion 17b and the second negative electrode on the negative electrode terminal 15 (see FIG. 1) side. It is divided into a side conduction path 16b2. The second elastic body 17h is mounted between the second negative electrode side conduction path 16b1 and the second negative electrode side conduction path 16b2. And when the space | interval holding | maintenance part 17d is blown out, the deformation | transformation of the terminal accompanying the expansion | extension of the elastic body 17c is absorbed. Since the second elastic body 17h forms a part of the conduction path of the negative electrode side conduction path 16, the second elastic body 17h may be made of the same material as that of the negative electrode side conduction path 16 (copper in this embodiment). Although not shown in the drawings, the second elastic body 17h is made of an insulating material, and is separately connected by connecting a conductive wire between the second negative electrode side conductive path 16b1 and the second negative electrode side conductive path 16b2. May be.

  Heretofore, various types of sealed batteries proposed here have been described. Unless otherwise stated, the embodiments of the sealed battery and the like listed here do not limit the present invention.

Here, the resistance heating element 17f is heated by the output from the switching unit 17g (see FIG. 1), and the interval holding unit 17d is broken. On the other hand, the space | interval holding | maintenance part 17d may be comprised mechanically by the drive device started with the output from the switching part 17g.
Further, the current interrupt mechanism 17 is provided in the negative electrode side conduction path 16, but may be provided in the positive electrode side conduction path 14. When the current interruption mechanism 17 is provided in the positive electrode side conduction path 14, it is desirable that the same material as that of the positive electrode side conduction path 14 is used for the electric wire 17e (see FIG. 2) of the current interruption mechanism 17.

DESCRIPTION OF SYMBOLS 10 Sealed battery 11 Electrode body 11a Positive electrode current collection part 11b Negative electrode current collection part 12 Battery case 13 Positive electrode terminal 14 Positive electrode side conduction path 15 Negative electrode terminal 16 Negative electrode side conduction path 16a First negative electrode side conduction path 16b Second negative electrode side conduction path 16b1 Second negative electrode side conduction path 16b2 on the side including the second end part 17b Second negative electrode side conduction path 17 on the negative electrode terminal 15 side Current interrupt mechanism 17a First end part 17b Second end part 17c Elastic body 17d Spacer holding part 17e Wire 17e1 First wire 17e2 Second wire 17f Resistance heating element 17f1 Resistance heating element first end 17f2 Resistance heating element second end 17g Switching portion 17g1 First input line 17g2 Second input line 17h Second elastic body G1 External power supply P1 power control unit

Claims (1)

An electrode body having a positive electrode current collector and a negative electrode current collector;
A battery case containing the electrode body;
A positive terminal attached to the battery case;
A positive-side conduction path connecting the positive-electrode current collector and the positive-electrode terminal;
A negative electrode terminal attached to the battery case;
A negative-side conduction path connecting the negative-electrode current collector and the negative-electrode terminal;
A current interruption mechanism provided in any one of the first conduction path and the positive conduction path and the negative conduction path, and blocking the first conduction path;
The current interruption mechanism is:
A pair of end portions where the first conduction path is divided;
An elastic body that exerts a force to increase the distance between the pair of end portions;
An interval holding unit that spans the pair of ends and holds the distance between the pair of ends;
An electric wire spanned between the pair of ends and joined to the pair of ends;
A resistance heating element attached to the gap holding unit;
A switching unit configured to detect a potential difference between the positive electrode side conduction path and the negative electrode side conduction path and to output a current to the resistance heating element when there is a potential difference higher than a predetermined potential difference; Prepared,
The interval holding unit is configured to be melted by heat generated by the resistance heating element,
The first conduction path connected by the electric wire is configured to be disconnected when the distance holding portion is melted and the distance between the pair of end portions is widened.
Sealed battery.

Images