JP6975386B2 - Sealed battery - Google Patents

Description

The present invention relates to a sealed battery.

Japanese Unexamined Patent Publication No. 2015-60658 discloses a secondary battery provided with a current cutoff unit that is blown off during overcharge to cut off current as a device for preventing overcharge.
The current cutoff unit proposed in the same publication cuts off the passing current when a current exceeding a predetermined threshold value flows. One of the current cutoff portions is connected to the positive electrode terminal, and the other is connected to the positive electrode short-circuit lead. The current cutoff section melts when the current flowing through the current cutoff section exceeds a predetermined threshold value, and cuts off the current flowing through the positive electrode short-circuit lead. For example, the current cutoff unit is said to be a fuse or the like.

Further, Japanese Patent Application Laid-Open No. 2013-157154 includes an additive that is electrolyzed to generate gas at the time of overcharging in the electrolytic solution. Then, gas is generated in the case of the sealed battery at the time of overcharging, and the internal pressure in the case of the sealed battery is increased. Then, a mechanism for interrupting the current has been proposed due to the increase in the internal pressure inside the case of the sealed battery.

Japanese Unexamined Patent Publication No. 2015-60658 Japanese Unexamined Patent Publication No. 2013-157154

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

Further, for example, in an application used as a drive source for an electric vehicle such as a plug-in hybrid vehicle or an electric vehicle, a sealed battery such as a lithium ion secondary battery is required to have a high capacity. As the capacity increases, the amount of active material contained in the battery case increases. Therefore, the amount of gas that can be generated even by normal charging / discharging tends to increase. Further, if the space inside the battery case is saved, the dead space is reduced. Therefore, a small amount of gas that can be generated by normal charging / discharging is gradually accumulated, and the internal pressure of the battery case tends to increase. Therefore, the present inventor considers that a relief valve is required in the battery case of the sealed battery in addition to the safety valve as the capacity is increased. However, if the relief valve is provided, the internal pressure of the battery case can be maintained at a constant level, so that it becomes difficult for the current cutoff mechanism that operates due to the increase in the pressure inside the battery case to operate.

One embodiment of the sealed battery proposed here is 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, and a positive electrode. A positive electrode side conduction path connecting the current collector and the positive electrode terminal, a negative electrode terminal attached to the battery case, a negative electrode side conduction path connecting the negative electrode current collector and the negative electrode terminal, and a positive electrode side conduction path and the negative electrode side. It is provided in the first conduction path of either one of the conduction paths, and is provided with a current cutoff mechanism that cuts off the first conduction path.
The current cutoff mechanism spans a pair of ends where the first conduction path is divided, an elastic body that exerts a force to increase the distance between the pair of ends, and a pair of ends. A space holding part that holds the distance between the two, an electric wire that is spanned over a pair of ends and joined to the pair of ends, a resistance heating element attached to the space holding part, and a positive electrode side conduction path and a negative electrode side conduction. It is provided with a switching unit configured to detect a potential difference from the path and output a current to a resistance heating element when there is a potential difference higher than a predetermined potential difference.
Here, the interval holding portion may be configured to be blown by the heat generated by the resistance heating element. Further, the first conduction path connected by the electric wire may be configured so as to be disconnected when the interval holding portion is blown and the distance between the pair of ends is widened.

As described above, in this sealed battery, the interval holding portion is configured to be blown by the heat generated by the resistance heating element. The first conduction path connected by the electric wire is configured to be disconnected when the interval holding portion is blown and the distance between the pair of ends is widened. Therefore, the energization of the battery is surely cut off at the time of overcharging.

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

Hereinafter, an embodiment of the sealed battery proposed here will be described. The embodiments described herein are, of course, not intended to specifically limit the invention. The invention is not limited to the embodiments described herein, unless otherwise noted. Each drawing is drawn schematically and does not necessarily reflect the real thing. Further, each drawing shows only one example, and does not limit the present invention unless otherwise specified. Further, members / parts having the same action are appropriately designated by the same reference numerals, and duplicate description will be omitted.

FIG. 1 is a schematic diagram of the 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, and a negative electrode side conduction path 16. It is provided with a current cutoff 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. The specific form of the electrode body 11 is not limited to the form exemplified here, unless otherwise specified. The sealed battery 10 may be, for example, an all-solid-state battery containing a solid electrolyte. The electrode body 11 may be used for an all-solid-state battery.

Although detailed illustration is omitted, the electrode body 11 may be, for example, a so-called laminated electrode body in which a positive electrode sheet and a negative electrode sheet are laminated with a separator sheet interposed therebetween. Further, as another form of the electrode body 11, the positive electrode sheet, the first separator sheet, the negative electrode sheet, and the second separator sheet are each made into a long strip-shaped member. The electrode body 11 may be a so-called wound electrode body in which a positive electrode sheet and a negative electrode sheet are laminated and wound with a long strip-shaped first separator sheet or a second separator sheet interposed therebetween.

The positive electrode sheet has, for example, a positive electrode active material layer containing a positive electrode active material on a positive electrode current collecting foil (for example, an aluminum foil), except for an unformed portion set at a certain width at one end in the width direction. It should be formed on both sides. The unformed portion where the positive electrode active material layer is not formed in the positive electrode current collecting foil can be the positive electrode current collecting portion 11a of the electrode body 11. The positive electrode active material is, for example, a material that can release lithium ions during charging and absorb lithium ions during discharging, such as a lithium transition metal composite material in a lithium ion secondary battery. Various positive electrode active materials have been generally proposed in addition to the lithium transition metal composite material, 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 collecting foil (for example, a copper foil) except for an unformed portion set to a certain width on one edge in the width direction. It should be done. The unformed portion where the negative electrode active material layer is not formed in the negative electrode current collecting foil can be the negative electrode current collecting portion 11b of the electrode body 11. The negative electrode active material is, for example, a material such as natural graphite in a lithium ion secondary battery, which can occlude lithium ions during charging and release the lithium ions occluded during charging during discharging. Various negative electrode active materials have been generally proposed in addition to natural graphite, and are not particularly limited.

As the separator sheet, for example, a porous resin sheet through which an electrolyte having a required heat resistance can pass is used. Various separator sheets have also 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 the separator sheet interposed therebetween. 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 unformed portion as the positive electrode current collector 11a and the unformed portion as the negative electrode current collector 11b are directed to opposite sides in the width direction. The unformed portion as the positive electrode current collector 11a protrudes from one side in the width direction of the separator sheet. The unformed portion as the negative electrode current collector 11b protrudes from the separator sheet on the opposite side in the width direction.

The electrode body 11 is housed in the battery case 12. The battery case 12 is schematically shown by a two-dot chain line in FIG. The battery case 12 may be, for example, a flat rectangular aluminum case.

The positive electrode terminal 13 is an electrode terminal attached to the battery case 12.
The positive electrode side conduction path 14 is a conduction path connecting the positive electrode current collector 11a 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 connecting the negative electrode current collector 11b 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 electrode terminal 13 and the negative electrode terminal 15 are connected to the external power supply G1 and the output device via the power control unit P1.

The current cutoff mechanism 17 is provided in the first conduction path 16 of either the positive electrode side conduction path 14 or the negative electrode side conduction path 16, and is a mechanism that cuts off 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 cutoff mechanism 17.
As shown in FIGS. 1 and 2, the current cutoff mechanism 17 switches between a pair of end portions 17a and 17b, an elastic body 17c, a spacing holding portion 17d, an electric wire 17e, and a resistance heating element 17f. It has a portion of 17 g.

In the pair of end portions 17a and 17b, the negative electrode side conduction path 16 as the first conduction path is divided at a portion where the current cutoff mechanism 17 is provided, and at the end of the divided negative electrode side conduction path 16. be. Here, the pair of ends 17a and 17b do not have to be the ends where the member constituting the negative electrode side conduction path 16 is actually cut. The negative electrode side conduction path 16 may be composed of 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. Then, 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 located at a portion where the current cutoff mechanism 17 is provided. It is good to face each other.

The elastic body 17c is a member that exerts a force so as to widen the distance between the pair of ends 17a and 17b of the negative electrode side conduction path 16 as the first conduction path. In this embodiment, as shown in FIG. 1, it is composed of a coil spring arranged in a compressed state between the pair of ends 17a and 17b. In this embodiment, the elastic body 17c uses a metal spring such as stainless steel (SUS) which is insulatingly coated with a heat-resistant resin, ceramic, or the like. That is, the elastic body 17c interposed in the pair of ends 17a and 17b of the negative electrode side conduction path 16 does not conduct the pair of ends 17a and 17b of the negative electrode side conduction path 16. The elastic body 17c may be arranged so as to exert a force so as to widen the distance between the pair of end portions 17a and 17b, and is not limited to such a 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 ends 17a and 17b and the spring. Further, the elastic body 17c is not limited to the coiled spring, and may be rubber.

The space holding portion 17d is a member that is bridged over a pair of end portions 17a and 17b and holds a distance between the pair of end portions 17a and 17b. In this embodiment, the space holding portion 17d is a member having a predetermined length. At both ends of the space holding portion 17d, 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. By attaching the interval holding portion 17d 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 are maintained at a predetermined distance. Will be done. In other words, the space 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 may be made of a metal or resin having a low melting point that can be melted when a current is applied to the resistance heating element 17f described later and the resistance heating element 17f generates heat.

The electric wire 17e is bridged over a pair of end portions 17a and 17b and joined to the pair of end portions 17a and 17b. In the form shown in FIG. 2, the electric wire 17e includes a first electric wire 17e1 and a second electric wire 17e2. The first electric wire 17e1 and the second electric wire 17e2 may be made of a conductive metallic wire or tape, respectively. Further, in FIG. 2, an example in which the electric wire 17e is composed of the first electric wire 17e1 and the second electric wire 17e2 is shown, but it may be further connected by a plurality of electric wires. The electric wire 17e may be slightly longer than the distance between the pair of ends 17a and 17b of the negative electrode side conduction path 16 maintained by the space holding portion 17d. It is preferable that the first electric wire 17e1 and the second electric wire 17e2 constituting the electric wire 17e and the pair of end portions 17a and 17b are joined by a conductive method. 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 blown and a force is applied by the elastic body 17c so as to widen 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, It is preferable that the connection with 17b is disengaged. The first electric wire 17e1 and the second electric wire 17e2 constituting the electric wire 17e and the pair of end portions 17a and 17b may be joined by a method such as wire bonding, for example.

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

Further, the second end portion 17f2 of the heating wire as the resistance heating element 17f may be connected to the output terminal of the switching portion 17g as shown in FIG.
The switching unit 17g is configured to detect the 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. There is.

Here, the switching unit 17g may be composed of, for example, a Zener diode configured to detect a predetermined overcharge voltage or an electronic circuit including a Zener diode. The switching unit 17g is connected to the positive electrode 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 electrode side conduction path 14 and the resistance heating element 17f.
The switching unit 17g detects the voltage based on the 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 the predetermined overcharge voltage, the switching unit 17g and the positive electrode side conduction path 14 It is insulated from the resistance heating element 17f. When the voltage detected by the switching unit 17g becomes equal to or higher than a predetermined overcharge voltage, the positive electrode side conduction path 14 and the resistance heating element 17f become conductive.

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 the predetermined overcharge voltage when the sealed battery 10 is connected to the external power supply G1. If it is charged. Therefore, when the positive electrode side conduction path 14 and the resistance heating element 17f are electrically connected by the switching unit 17g, a circuit of an external power supply G1, a positive electrode side conduction path 14, a switching unit 17g, a resistance heating element 17f, and a negative electrode side conduction path 16 is formed. Will be done. Therefore, using 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 becomes equal to or higher than a predetermined overcharge voltage, the positive electrode side conduction path 14 and the resistance heating element 17f Conducts and the resistance heating element 17f generates heat. When the resistance heating element 17f generates heat, the interval holding portion 17d is blown.

Here, FIG. 3 is an enlarged view of the current cutoff mechanism 17. In FIG. 3, the resistance heating element 17f is not shown.
As shown in FIG. 3, when the space holding portion 17d is blown, the distance between the pair of end portions 17a and 17b is widened. At this time, the negative electrode side conduction path 16 as the first conduction path connected by the electric wire 17e is disconnected. Further, the electric wire 17e may be composed of a plurality of electric wires 17e1 and 17e2 as described above. Then, it is preferable that the interval holding portion 17d is configured to be sequentially broken after being blown.

FIG. 3 shows a state in which the interval holding portion 17d is blown and the first electric wire 17e1 of the electric wires 17e and the second end portion 17b of the negative electrode side conduction path 16 are disconnected. After that, the connection between the second electric wire 17e2 and the second end portion 17b is further disconnected, and the negative electrode side conduction path 16 is disconnected. Further, when the electric wire 17e is further composed of a plurality of electric wires, all the electric wires are sequentially broken.
The elastic body 17c may be configured to widen the distance between the pair of end portions 17a and 17b until the negative electrode side conduction path 16 is disconnected due to the disconnection of the electric wire 17e. When the voltage detected by the switching unit 17g drops after the wire is disconnected, the energization of the heating wire is stopped.

FIG. 4 is an enlarged view of the current cutoff mechanism 17 in another form. Here, the members or parts that perform the same function as in FIG. 2 are given the same sign.
As shown in FIG. 4, the 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 is 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. Then, when the space holding portion 17d is blown, the deformation of the terminal due to the elongation 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, it is preferable that the second elastic body 17h is made of the same material as the negative electrode side conduction path 16 (copper in this embodiment). Although not shown, the second elastic body 17h is used as an insulating material, and a conduction wire is separately bridged and connected to the second negative electrode side conduction path 16b1 and the second negative electrode side conduction path 16b2. May be done.

The sealed batteries proposed here have been described in various ways. Unless otherwise specified, the embodiments of the sealed battery mentioned 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) to break the interval holding unit 17d. On the other hand, the interval holding portion 17d may be mechanically broken by the driving device activated by the output from the switching portion 17g.
Further, although the current cutoff mechanism 17 is provided in the negative electrode side conduction path 16, it may be provided in the positive electrode side conduction path 14. When the current cutoff mechanism 17 is provided in the positive electrode side conduction path 14, it is desirable that the same material as the positive electrode side conduction path 14 is used for the electric wire 17e (see FIG. 2) of the current cutoff mechanism 17.

10 Sealed battery 11 Electrode body 11a Positive electrode current collector 11b Negative electrode current collector 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 17b Second negative electrode side conduction path 17 on the negative electrode terminal 15 Current cutoff mechanism 17a First end 17b Second end 17c Elastic body 17d Spacing holding portion 17e Wire 17e1 First wire 17e2 Second wire 17f Resistance heating element 17f1 First end of resistance heating element 17f2 Second end of resistance heating element 17g Switching part 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,
The battery case in which the electrode body is housed and
The positive electrode terminal attached to the battery case and
A positive electrode side conduction path connecting the positive electrode current collector and the positive electrode terminal,
The negative electrode terminal attached to the battery case and
A negative electrode side conduction path connecting the negative electrode current collector and the negative electrode terminal,
A current cutoff mechanism provided in the first conduction path of either the positive electrode side conduction path or the negative electrode side conduction path and interrupting the first conduction path is provided.
The current cutoff mechanism is
A pair of ends where the first conduction path is divided,
An elastic body that exerts a force to increase the distance between the pair of ends,
An interval holding portion that is bridged over the pair of ends and holds the distance between the pair of ends,
An electric wire spanned over the pair of ends and joined to the pair of ends,
With the resistance heating element attached to the space holding part,
A switching unit configured to detect a potential difference between the positive electrode side conduction path and the negative electrode side conduction path and output a current to the resistance heating element when there is a potential difference higher than a predetermined potential difference. Prepare,
The interval holding portion is configured to be blown by the heat generated by the resistance heating element.
The first conduction path connected by the electric wire is configured to be disconnected when the interval holding portion is blown and the distance between the pair of ends is widened.
Sealed battery.

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