JP2019129095A - Sealed battery - Google Patents

Abstract

To propose a sealed battery including a current interruption mechanism capable of reliably interrupting a current at the time of overcharging.SOLUTION: A current interruption mechanism 17 includes: a conducting part 17a made of a plurality of aluminum wires or an aluminum foil and forming a part of a positive electrode side conducting path; an enclosure 17b enclosing the conducting part 17a; an electrolyte 17c sealed in the enclosure 17b; and a contact piece 17d comprising metal nobler than aluminum and penetrating through the enclosure 17b. A drive device is constituted so as to bring the contact piece 17d into contact with the conducting part 17a when receiving output from a voltage detection part.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a sealed battery.

JP-A-2015-60658 discloses a secondary battery provided with a current interrupting unit which is melted down at the time of overcharging to interrupt the 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 interrupter is considered to be a fuse or the like.

  Moreover, in Unexamined-Japanese-Patent No. 2013-157154, the additive which makes it electrolyze at the time of overcharge and generate | occur | produces gas is included in electrolyte 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 of the internal pressure in the case of the sealed battery.

Unexamined-Japanese-Patent No. 2015-60658 JP, 2013-157154, A

  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.

  Further, for example, in applications used as a drive source of an electric-powered vehicle such as a plug-in hybrid vehicle or an electric vehicle, higher capacity is required for a sealed battery such as a lithium ion secondary battery. As the capacity increases, the amount of active material contained in the battery case increases. For this reason, the gas which may be produced also by usual charge and discharge tends to be large. Furthermore, if space saving in the battery case is achieved, the dead space is reduced. For this reason, a trace amount of gas that can be generated by normal charge and discharge is gradually accumulated, and the internal pressure of the battery case tends to be high. Therefore, the inventor of the present invention thinks that, with the increase in capacity, a relief valve is required in the battery case of the sealed battery separately from 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 increase of the 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, and a positive-side conduction path. A current blocking mechanism that blocks the positive-side conduction path, a voltage detection unit that outputs a current when the potential difference between the positive-side conduction path and the negative-side conduction path is higher than a predetermined potential difference, and a voltage detection unit And a driving device that operates the current interrupting mechanism to interrupt the positive electrode side conduction path.

  The current interrupting mechanism consists of a plurality of aluminum wires or aluminum foils, a conducting part that forms part of the positive-side conduction path, an enclosure that surrounds the conducting part, an electrolyte enclosed in the enclosure, and a metal that is nobler than aluminum And a contact piece penetrating the enclosure. The drive device is configured to bring the contact piece into contact with the conductive portion when receiving the output from the voltage detection unit.

  In this sealed battery, the contact piece is configured to be in contact with the conduction portion in response to an output from the voltage detection unit during overcharge. The contact piece is made of a metal nobler than aluminum, and the conductive portion elutes in the enclosure, and the positive-side conductive path is disconnected. As a result, energization of the battery is cut off more reliably.

FIG. 1 is a schematic view of a sealed battery 10. FIG. 2 is an enlarged view of the current interrupting mechanism 17. FIG. 3 is an enlarged view of the current interrupting mechanism 17 in another form. FIG. 4 is an enlarged view of the current interruption mechanism 17 showing a state in which the current is interrupted.

  Hereinafter, an embodiment of a 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. Also, each drawing shows only one example, and does not limit the present invention unless otherwise stated. In addition, the same reference numerals are appropriately given to members and portions exhibiting the same function, and the overlapping description will be 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, a voltage detection unit 18, and a drive device 19 are provided.

  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 limited in particular. The sealed battery 10 may be, for example, an all solid 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 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 unformed portion where the positive electrode active material layer is not formed in the positive electrode current collector foil can be the positive electrode current collector portion 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 done. An unformed portion where the negative electrode active material layer is not formed in the negative electrode current collector foil can be the negative electrode current collector portion 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 types of 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 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 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 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.

FIG. 2 is an enlarged view of the current interrupting mechanism 17.
As shown in FIG. 2, the current interruption mechanism 17 includes a conduction portion 17a, an enclosure 17b, an electrolytic solution 17c, and a contact piece 17d.

  Conducting portion 17a is a portion which is made of a plurality of aluminum wires or aluminum foils and forms a part of the positive electrode side conduction path. In this embodiment, the conduction part 17a includes terminals 17a1 and 17a2 attached to the enclosure 17b, and a disconnection part 17a3 made of a plurality of aluminum wires or aluminum foils. The terminals 17a1 and 17a2 are attached to each other so as to face each other and to pass through the enclosure 17b. The disconnection portion 17a3 is wired so as to connect the opposing terminals 17a1 and 17a2. When an aluminum wire is used for the disconnection portion 17a3, the diameter of the aluminum wire may be approximately 10 μm or more and 1000 μm or less. When an aluminum foil is used for the broken portion 17a3, the thickness of the aluminum foil is preferably approximately 1 μm to 100 μm. Moreover, it is preferable that the cross-sectional areas of a plurality of aluminum wires or aluminum foils used for the disconnection portion 17a3 are combined to have a cross-sectional area that can sufficiently allow current input and output in the sealed battery 10.

  The enclosure 17 b is a member that encloses the conduction portion 17 a. In this embodiment, the enclosure 17b is configured of a substantially rectangular resin case. The terminals 17a1 and 17a2 of the conduction portion 17a pass through the facing surfaces of the enclosure 17b. And in the inside of the enclosure 17b, the disconnection part 17a3 which consists of several aluminum wire or aluminum foil is wired between terminal 17a1, 17a2.

The electrolytic solution 17c may be enclosed in an enclosure 17b. The electrolyte solution 17c may be a solution for ensuring electrical conductivity inside the enclosure 17b. It does not contribute to the battery reaction of the sealed battery 10. It may be a solution different from the electrolytic solution contained in the sealed battery 10 together with the electrode body 11. The same solution as the electrolytic solution contained in the sealed battery 10 together with the electrode body 11 may be used. As the electrolytic solution 17c, for example, a solution obtained by dissolving an electrolyte salt such as LiPF _{6 in} a mixed solvent such as ethylene carbonate and dimethyl carbonate can be used.

  The contact piece 17d is made of a metal (such as copper) nobler than aluminum and penetrates the enclosure 17b. In this embodiment, the enclosure 17b is disposed in the vicinity of the terminal 17a2 of the conducting portion 17a. The contact piece 17d may be formed of a metal shaft or a metal plate, and may be provided to penetrate the enclosure 17b.

  For example, a conductive portion 17a is prepared in which a disconnection portion 17a3 made of an aluminum wire or an aluminum foil is wired between the terminals 17a1 and 17a2. An enclosure 17b is prepared which is comprised of a half-split case configured to be split at an intermediate portion of the surface to which the terminals 17a1 and 17a2 are attached. And the hollow for attaching terminal 17a1, 17a2 is formed in the edge of the case of the half type which comprises enclosure 17b. In addition, it is preferable that an injection hole for injecting the electrolyte solution 17c be formed in the case of the half type which constitutes the enclosure 17b. In addition, it is preferable that the contact piece 17d be attached so as to penetrate in the vicinity of the recess for attaching the terminal 17a2.

The enclosure 17b is closed together with the half-shaped case to which the terminals 17a1 and 17a2 are attached. At this time, it is preferable to weld so that there is no liquid leakage at the joint of the enclosure 17b and the attachment portions of the terminals 17a1 and 17a2. As described above, the electrolytic solution 17c is injected into the enclosure 17b in a state where the conducting portion 17a is attached to the enclosure 17b and the enclosure 17b is closed. After the electrolytic solution 17c is injected, the injection hole into which the electrolytic solution has been injected may be sealed.
The current interrupting mechanism 17 after the electrolyte solution 17c is injected is arranged with the terminal 17a2 and the contact piece 17d of the conduction part 17a facing downward.

  The voltage detector 18 is configured to output a current when the potential difference between the positive-side conduction path 14 and the negative-side conduction path 16 is higher than a predetermined potential difference. The voltage detection unit 18 may be configured by, for example, a Zener diode or an electronic circuit including a Zener diode.

  Here, the potential difference between the positive electrode side conduction path 14 and the negative electrode side conduction path 16 is a potential difference between the potential of the positive electrode side conduction path 14 and the potential of the negative electrode side conduction path 16. The potential of the positive electrode side conduction path 14 may be any one of the positive electrode current collector 11 a, the positive electrode side conduction path 14, and the positive electrode terminal 13 in the battery case 12. The potential of the negative electrode side conduction path 16 may be any one of the negative electrode current collector 11 b, the negative electrode side conduction path 16, and the negative electrode terminal 15 in the battery case 12. For example, in FIG. 1, one end of the voltage detection unit 18 is connected to the positive-side conduction path 14 via the current interrupt mechanism 17 and the drive device 19, and the other end of the voltage detection unit 18 is connected to the negative electrode current collector 11 b. It is connected to the. Thereby, when the potential difference between the positive electrode side conduction path 14 and the negative electrode side conduction path 16 is higher than a predetermined potential difference, a current is output to the driving device 19.

  When the voltage detected based on the potential difference between the positive-side conduction path 14 and the negative-side conduction path 16 is lower than a predetermined overcharge voltage, the voltage detection unit 18 and the positive-side conduction path 14 The side conduction path 14 and the negative side conduction path 16 are insulated. When the voltage detected by the voltage detector 18 is equal to or higher than a predetermined overcharge voltage, the drive device 19 and the positive-side conduction path 14 and the negative-side conduction path 16 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 because it is connected to the external power source G1 and the sealed battery 10 Is charged. Therefore, when the drive device 19 and the positive-side conduction path 14 and the negative-side conduction path 16 are conducted by the voltage detector 18, the external power supply G1, the positive-side conduction path 14, the drive device 19, and the negative-side conduction path 16 are referred to. A closed circuit is formed. Therefore, the drive device 19 can be operated with the external power supply G1 as a power supply.

FIG. 3 is an enlarged view of the current interrupt mechanism 17 according to another embodiment.
The drive device 19 is configured such that the contact piece 17d contacts the conduction portion 17a in response to the output from the voltage detection unit 18. For example, the driving device 19 may be a mechanism that is placed outside the enclosure 17b and applies a force F2 to the contact piece 17d to deform the contact piece 17d to contact the conduction portion 17a. For example, the insulating member 17e is interposed between the contact piece 17d and the terminal of the conducting portion 17a. In addition, a spring that pushes the contact piece 17d toward the conduction portion 17a is disposed. The driving device 19 may operate so as to remove the insulating member 17e. In this case, the contact piece 17d may be a sheet-like soft member.

  As another modification, the driving device 19 may be configured to receive an output from the voltage detection unit 18 and to apply a force to the contact piece 17d by a piezoelectric element. Further, the heater (electric heating wire) and the bimetal may be combined, and the heater may be heated by the output from the voltage detection unit 18 to drive the bimetal and apply a force to the contact piece 17d. The resin as the insulating member 17e disposed between aluminum and copper may be melted by heat.

FIG. 4 is an enlarged view of the current interrupt mechanism 17 showing a state where the current is interrupted. FIG. 4 shows a state in which the current is interrupted in the current interruption mechanism 17 shown in FIG.
As shown in FIG. 4, the driving device 19 receives an output from the voltage detection unit 18 and applies a force F1 to the contact piece 17d so that the contact piece 17d contacts the conduction portion 17a. When the contact piece 17d contacts the conduction part 17a, the aluminum used for the conduction part 17a and the copper used for the contact piece 17d come into contact. At this time, since aluminum is a base metal rather than copper, the conductive portion 17a and the contact piece 17d form an internal battery in the electrolytic solution. For this reason, the conduction | electrical_connection part 17a elutes in the enclosure 17b. In the conductive portion 17a, the broken portion 17a3 is formed of aluminum wire or aluminum foil, and dissolves quickly. When the disconnection portion 17a3 is eluted, the positive electrode side conduction path 14 is disconnected. As described above, according to the current interrupting mechanism 17, the voltage detected by the voltage detection unit 18 becomes equal to or higher than the predetermined overcharge voltage. The drive device 19 and the positive electrode side conduction path 14 are electrically connected to the negative electrode side conduction path 16. In addition, if the voltage detected by the voltage detection part 18 falls after the positive electrode side conduction | electrical_connection path 14 is disconnected, the output to the drive device 19 will be stopped.

  In the above, various descriptions have been made of the sealed battery proposed here. Unless otherwise stated, the embodiments of the sealed battery and the like listed here do not limit the present invention.

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 17 Current interruption mechanism 17a Conduction part 17a1 Terminals 17a1, 17a2 Terminal 17a3 Disconnection part 17b Enclosure 17c Electrolyte 17d Contact piece 17e Insulating member 18 Voltage detection part 19 Drive device F1 Force F2 Force 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 interrupting mechanism attached to the positive electrode side conduction path for interrupting the positive electrode side conduction path;
A voltage detector that outputs a current when a potential difference between the positive-side conduction path and the negative-side conduction path is higher than a predetermined potential difference;
A driving device configured to receive the output from the voltage detection unit and operate the current interrupting mechanism to interrupt the positive electrode side conduction path;
The current interruption mechanism is:
A conductive portion made of a plurality of aluminum wires or aluminum foils and forming a part of the positive electrode side conductive path;
An enclosure enclosing the conducting portion;
An electrolyte solution enclosed in the enclosure;
It is composed of a noble metal than the aluminum, and includes a contact piece penetrating the enclosure,
The driving device is
When the output from the voltage detection unit is received, the contact piece is configured to contact the conduction portion.
Sealed battery.

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