JP6111856B2 - Power storage device - Google Patents

Description

  The present invention relates to a sealed power storage device. Specifically, the present invention relates to a power storage device including a current interrupt device that interrupts current when the internal pressure of the case increases due to overcharging or the like.

  In recent years, power storage devices such as lithium ion batteries, nickel metal hydride batteries, and other secondary batteries (storage batteries) have become increasingly important as power sources for mounting on vehicles, or power sources for personal computers and portable terminals. In particular, a lithium ion battery that is lightweight and obtains a high energy density is expected to be preferably used as a high-output power source mounted on a vehicle. One typical structure of such a secondary battery is a battery having a sealed structure (sealed battery) in which a case in which an electrode assembly and an electrolyte are accommodated is hermetically sealed.

  By the way, when this type of battery is charged, if a malfunction occurs due to the presence of a defective battery or a failure of the charging device, it is assumed that a current higher than normal is supplied to the battery and the battery is overcharged. In the case of battery abnormality such as overcharge, gas is generated inside the sealed battery case, the internal pressure of the case increases, and the battery swells due to the abnormal internal pressure (gas pressure), which may cause problems. In order to cope with such an abnormality, as a conventional technique, there is a battery structure including a current interrupt device for interrupting current and ensuring battery safety when the internal pressure of a sealed battery case exceeds a predetermined level. It has been proposed (see, for example, Patent Documents 1-4). The current interrupt device interrupts an energization path between the battery assembly and an electrode terminal (external terminal) exposed to the outside of the case.

  The technique of Patent Document 1 includes an internal electrode that is electrically connected to an electrode assembly and a diaphragm that is electrically connected to an external terminal. The internal electrode and the diaphragm face each other. A hole is provided in the internal electrode. At the center of the diaphragm, a protrusion that fits into the hole of the internal electrode is provided. While the diaphragm protrusion is fitted in the hole of the internal electrode, the electrode assembly and the external terminal are electrically connected. The overall shape of the diaphragm is a mortar shape protruding toward the internal electrode, and the protrusion protruding in the same direction as the protruding direction of the mortar is provided at the center. The side of the diaphragm facing the internal electrode communicates with the case internal space, and the opposite side faces the space isolated from the case internal pressure. When the case internal pressure increases, pressure is applied to the diaphragm. The pressure acts in a direction in which the diaphragm is separated from the internal electrode, that is, in a direction in which the protrusion is pulled out from the hole. When the case internal pressure exceeds a predetermined level, the diaphragm is pushed by the case internal pressure, and the protrusion is detached from the hole of the internal electrode, thereby interrupting the energization path. Patent Document 2 discloses a similar technique.

  The structure disclosed in Patent Document 3 is similar to the technique of Patent Document 1. However, the member corresponding to the internal electrode in Patent Document 1 is made of an insulating material. In Patent Document 3, the member is an insulator (insulator). A safety valve is arranged so as to face the insulator. The safety valve corresponds to the diaphragm of Patent Document 1. The overall shape of the safety valve is a mortar shape projecting toward the insulator, and a projection projecting in the same direction as the projecting direction of the mortar is provided at the center thereof. A hole that engages with the protrusion of the safety valve is provided in the center of the insulator. The tip of the protrusion passes through the insulator, and is joined to a conductive plate in conduction with the electrode assembly on the surface opposite to the safety valve. The space between the insulator and the safety valve communicates with the internal space of the case, and is maintained at the same pressure as the internal pressure of the case. The internal pressure of the case acts in a direction to move the safety valve away from the insulator, and when the internal pressure exceeds a predetermined level, the protrusion of the safety valve is detached from the hole of the insulator. At that time, a part of the conductive plate joined to the protrusion of the safety valve is broken, and the energization path is interrupted.

  Patent Document 4 discloses a similar technique. The power storage device of Patent Document 4 also has a plate that deforms when the case internal pressure increases. The plate is usually in the shape of a mortar that protrudes to one side, and has a protrusion that protrudes in the same direction as the protrusion of the mortar at the center. The protrusion is in contact with the internal terminal. When the case internal pressure rises, the curvature of the mortar is reversed, the protrusion moves away from the internal terminal, and the contact between the protrusion and the internal terminal is blocked.

JP 2000-077058 A JP 2000-113873 A JP 2009-266714 A JP 2000-113834 A

  Each of the techniques disclosed in Patent Documents 1 to 4 has a contact plate that faces a space that holds the same pressure as the pressure in the case space and deforms when the case pressure increases. In patent documents 1 and 2, it is called a diaphragm, and in patent document 3, it is called a safety valve. Each contact plate is also in a mortar shape, and includes a protrusion protruding in the center in the same direction as the protruding direction of the mortar. Usually, the tip end surface of the protrusion is in contact with another conductive member, and conduction between the electrode assembly and the external terminal is ensured. When the case internal pressure increases, the contact plate is deformed so as to protrude to the opposite side to the original. As a result, the central protrusion is separated from the conductive member, or with the deformation of the contact plate, the portion of the conductive member that is in contact with the protrusion is broken and the energization path is interrupted.

  The contact plate may be deformed as planned when the internal pressure of the case exceeds a predetermined level. However, when unscheduled deformation occurs, the contact plate and the conductive member come close to each other, and once the energization path is interrupted, the contact plate is restarted. There is a risk of conduction. Alternatively, when the case internal pressure exceeds a predetermined level and the contact plate is deformed and the energization path is interrupted, when the impact or vibration is applied to the storage battery, the contact plate may be further deformed unexpectedly and re-conducted.

The technology disclosed in the present specification provides a power storage device including an energization interrupting device that reduces the possibility that an unscheduled deformed portion of a contact plate comes into contact with a conducting member and re-conducts.

  As described above, the conventional current interrupting device is formed in a mortar shape protruding in one direction, and has a contact plate provided with a protrusion protruding in the same direction as the protruding direction of the mortar at the center. In other words, the contact plate as a whole is a mortar, and a protrusion is provided at the center. The front end surface of the protrusion comes into contact with another member, and the energization path between the external terminal and the electrode assembly is secured. Hereinafter, another member that comes into contact with the front end surface of the protrusion of the contact plate is referred to as an energization plate.

  According to the inventors' investigation, after the contact plate is deformed and the tip end surface of the protrusion is separated from the current-carrying plate, the plate surface connected to the base of the protrusion is located near the current-carrying plate at the center portion of the mortar shape. I noticed that the area around the protrusion is likely to make unexpected contact with the current-carrying plate. For easy understanding, the plate surface connected to the base of the protrusion is hereinafter referred to as a “base flange portion”.

  In the technology disclosed in this specification, a current plate that is electrically connected to one of the electrode assembly and the external terminal, and a contact plate that is electrically connected to the other of the electrode assembly and the external terminal and are opposed to the current plate are provided. In the current interrupting device provided, the following structural features are added to the contact plate. In other words, the contact plate is provided with a protrusion whose tip surface is in contact with the energizing plate. Furthermore, in the cross section perpendicular to the above-described distal end surface, the base flange portion of the protrusion (a plate surface connected to the base) and the side surface of the protrusion form an acute angle. Alternatively, the base flange portion of the protrusion is curved so as to protrude in a direction away from the energizing plate. The structure in which the base flange portion forms an acute angle with the side surface of the protrusion means that the height of the protrusion from the base flange portion to the tip surface can be increased, which means that the tip surface of the protrusion Means that the distance between the base flange portion and the current-carrying plate can be increased in a state of being separated from the current-carrying plate. Similarly, in the structure in which the base flange portion is bent in the direction away from the energization plate, the distance between the base flange portion and the energization plate can be increased in a state where the distal end surface of the protrusion is separated from the energization plate. By increasing the distance between the energizing plate and the base flange portion in a state in which the tip end surface of the protrusion is separated from the energizing plate, the possibility that the base flange portion (ie, the contact plate) is reconnected to the energizing plate is reduced.

  One embodiment of a power storage device disclosed in this specification includes the following configuration. The power storage device includes a current interrupt device that interrupts an energization path between an electrode assembly inside the case and an external terminal exposed to the outside of the case when the case internal pressure exceeds a predetermined level. The current interrupting device includes an energizing plate that is electrically connected to one of the electrode assembly and the external terminal, and a contact plate that is electrically connected to the other of the electrode assembly and the external terminal and is disposed opposite to the energizing plate. At the substantial center of the contact plate, there is provided a protrusion whose tip surface is in contact with the energizing plate. The front end surface of the protrusion is electrically connected to the energizing plate. Further, the contact plate is curved so that the base flange and the side surface of the protrusion form an acute angle in a cross section perpendicular to the tip surface of the protrusion, or the base flange protrudes in a direction away from the current-carrying plate. Yes. When the contact plate receives a load exceeding a predetermined threshold load, the contact plate is deformed so that the front end surface of the protrusion is separated from the energizing plate. Specifically, both ends or the periphery of the contact plate are fixed so that when a load exceeding a threshold load is applied, the contact plate jumps in a direction away from the energizing plate and causes a shape change due to buckling. Both ends or the periphery of the contact plate are fixed directly or indirectly to the casing of the current interrupt device. “Jointly” means, for example, a case where a resin part is fixed to a housing and a contact plate is fixed to the resin part. Typically, the casing of the current interrupt device is cylindrical, and the contact plate is fixed inside the casing of the casing.

  Snap buckling means that when a load is applied from the curved protruding direction to a plate that is supported at both ends or the periphery so that the whole is curved and the center protrudes to one side, When the threshold load is exceeded, this refers to a phenomenon in which discontinuous deformation occurs so that the bending direction of the plate material is reversed to the other side at once, and the reversed shape is not restored even when the load is removed.

  In order to cause jumping and buckling, the contact plate has a diaphragm portion that is continuous with the edge of the base flange portion and surrounds the base flange portion. The diaphragm portion is a mortar-shaped plate that protrudes toward the energization plate. When the diaphragm portion or the protrusion receives a load exceeding a predetermined threshold load (a load in a direction away from the energization plate), the diaphragm portion is energized. It jumps in a mortar shape protruding in the direction away from and causes buckling. In this case, the diaphragm portion is deformed, but the protrusion and the base flange portion are not deformed.

  In the power storage device disclosed in the present specification, the contact plate has a protrusion that contacts the current-carrying plate, and the base flange portion connected to the side surface of the protrusion is away from the current-carrying plate, so that reconnection with the current-carrying plate is possible. Can be reduced. At the same time, the contact plate jumps and buckles away from the energizing plate. Therefore, even if the case internal pressure decreases, the contact plate does not return to its original shape, and re-conduction is prevented.

  There are three possible configurations for jumping to the contact plate and causing buckling due to an increase in the internal pressure of the case.

  The first configuration is a configuration in which the contact plate directly receives the case internal pressure. Specifically, the contact plate faces the first space where the surface facing the energization plate is maintained at the same pressure as the case internal pressure, and the surface opposite to the energization plate is isolated from the case internal space. It is arranged so as to face the second space. With such an arrangement, when the diaphragm portion of the contact plate receives a case internal pressure exceeding a predetermined level, it jumps and causes buckling. Here, the “second space isolated from the case internal space” means a space that is not affected by the pressure in the case internal space.

  The second configuration is a configuration in which a breakable portion that is easily broken is provided on the energizing plate so that the broken portion receives the internal pressure of the case. Specifically, the energization plate is provided with a breakage portion that breaks when it receives a load exceeding a predetermined threshold load and separates from the surroundings, and the breakage portion is in contact with the tip surface of the contact plate. The current plate faces the first space where the surface opposite to the contact plate is held at the same pressure as the case internal pressure, and the surface facing the contact plate is isolated from the case internal space. Arrange to face the space. When the internal pressure of the case exceeds a predetermined level, the fracture portion breaks. Here, the total pressure applied to the tip surface when the internal pressure of the case reaches a predetermined level and the fracture portion breaks is adjusted so as to correspond to the predetermined threshold load described above. By adjusting in such a manner, the contact plate jumps and buckles due to the momentum of breaking. In addition, in order to make it easy to fracture | rupture a fracture | rupture part in an electricity supply board, the perforation (perforation) or groove | channel which divides a fracture | rupture part and the remainder is provided in an annular shape. This groove divides the fractured portion and the remaining portion in the energizing plate.

  In the third configuration, the current-carrying plate includes the above-described fracture portion, but another plate is deformed by the internal pressure of the case, and the deformed portion of the other plate collides with the fracture portion to break the fracture portion. Specifically, the deformation plate is provided so as to face the energization plate on the side opposite to the side where the contact plate exists. The deformation plate has the following structure. The deformable plate faces the first space where one surface is maintained at the same pressure as the case internal pressure, and the other surface faces the current-carrying plate in the second space isolated from the case internal space. Be placed. The deformable plate has a mortar shape that protrudes entirely toward the first space, and a punching protrusion that protrudes toward the fracture portion is provided at the center. When the internal pressure of the case reaches a predetermined level, the deformed plate jumps from the mortar shape protruding toward the first space to the mortar shape protruding toward the second space, causing buckling, and the punching protrusion collides with the fractured portion. To do. When the fractured portion breaks, the rigidity of the contact plate and the rigidity of the deformation plate are adjusted so that the contact plate also jumps and buckles due to the impact. In this configuration, in addition to the load due to the internal pressure of the case, the fracture portion is broken by the impact of the punching projection colliding. That is, the broken portion can be broken more reliably than before.

  Details and further improvements of the technology disclosed in this specification will be described in detail in the following section of the detailed description.

  According to the present invention, in the power storage device, when the case internal pressure exceeds a predetermined level, the possibility of re-conduction of the energization interruption device that interrupts the energization between the electrode assembly and the external terminal can be reduced.

The longitudinal cross-sectional view of the electrical storage apparatus which concerns on 1st Example of this invention is shown. It is a longitudinal cross-sectional view which shows the detail of the electric current interruption apparatus of 1st Example, Comprising: (A) shows the structure in an energized state, (B) shows the structure in the state where the case internal pressure rose and the energization path was interrupted | blocked Show. FIG. 3A is an enlarged longitudinal sectional view of the current interrupting device in FIG. FIG. 3B is an enlarged longitudinal sectional view of the current interrupting device in FIG. FIG. 4A is an enlarged longitudinal sectional view of the current interrupting device of the second embodiment (energized state). FIG. 4B is an enlarged longitudinal sectional view of the current interrupt device of the second embodiment (energized path interrupted state). FIG. 5A is an enlarged longitudinal sectional view of the current interrupting device of the third embodiment (energized state). FIG. 5B is an enlarged longitudinal sectional view of the current interrupt device of the third embodiment (energized path interrupted state). FIG. 6A is an enlarged longitudinal sectional view of the current interrupting device of the fourth embodiment (energized state). FIG. 6B is an enlarged longitudinal sectional view of the current interrupting device of the fourth embodiment (energized path interrupted state).

  Although the form for implementing the electrical storage apparatus of this invention is demonstrated in detail, referring drawings, in this specification, various things other than an electric current interruption apparatus can be used. In addition, a power storage device described below can be mounted on, for example, a vehicle and can supply electric power to a motor.

  As examples of the power storage device, a sealed secondary battery, a sealed capacitor, and the like can be given. As an example of a secondary battery, a secondary battery such as a lithium ion battery, a nickel hydride battery, a nickel cadmium battery, or a lead storage battery can be cited as a type of battery that is charged and discharged with a relatively high capacity and a large current. In addition, as an example of an electrode assembly of a secondary battery, a stacked type electrode assembly in which a plurality of cells having electrode pairs (positive electrode and negative electrode) opposed via a separator are stacked, and electrodes opposed via a separator Examples thereof include a wound electrode assembly in which sheet-like cells having pairs are processed into a spiral shape. In the following description, a power storage device in which both the positive external terminal and the negative external terminal are exposed in one direction of the case will be described. However, the technique disclosed in this specification is a state in which the case functions as a terminal of one polarity (for example, a negative electrode) and the terminal of the other polarity (for example, the positive electrode) is insulated from the case as in a cylindrical battery. The present invention can also be applied to a power storage device of a type fixed to the case.

  (First Embodiment) FIG. 1 is a cross-sectional view of a stacked power storage device 100 according to a first embodiment. The power storage device 100 includes a case 1, an electrode assembly 60, tab groups 65 and 67, a first positive electrode conductive member 13, a second positive electrode conductive member 68, a negative electrode conductive member 64, and a positive electrode external terminal. 19, a negative external terminal 119, insulating members 61 and 66, and a current interrupt device 2. The electrode assembly 60 is sandwiched between and separated from a positive electrode sheet including a positive electrode active material and a positive electrode metal foil, a negative electrode sheet including a negative electrode active material and a negative electrode metal foil, and the positive electrode sheet and the negative electrode sheet. And a sheet-like separator. The electrode assembly 60 is a laminate in which a large number of positive electrode sheets, separators, and negative electrode sheets are laminated in this order, and is impregnated with a liquid electrolyte.

  The case 1 is a substantially rectangular parallelepiped box-shaped member, and includes an electrode assembly 60, tab groups 65 and 67, a first positive electrode conductive member 13, a second positive electrode conductive member 68, and a negative electrode conductive member. 64, insulating members 61 and 66, and the current interrupting device 2 are accommodated. A positive external terminal 19 and a negative external terminal 119 are exposed from the case on the upper end surface of the case 1. The metal foils of the plurality of positive electrode sheets of the electrode assembly 60 each have a tab portion, and the tab group 67 is formed by bundling the plurality of tab portions. Similarly, the metal foils of the plurality of negative electrode sheets each have a tab portion, and the plurality of tab portions are bundled to form a tab group 65. The electrode assembly 60 is covered with an insulating film, and protrudes from the insulating film at portions connected to the tab groups 67 and 65.

  The tab groups 65 and 67 extend from the electrode assembly 60 toward the upper end surface of the case 1, bend toward the front side of the paper surface of FIG. 1 and have a flat portion substantially parallel to the upper end surface of the case 1. It is formed into a shape.

  As shown in FIG. 1, the negative electrode conductive member 64 is a flat conductive member. The negative electrode conductive member 64 extends substantially parallel to the upper end surface of the case 1 from the tab group 65 toward the negative electrode external terminal 119. The negative electrode conductive member 64 and the tab group 65 are fixed by welding. As described above, the negative electrode energization path from the negative electrode of the electrode assembly 60 to the negative electrode external terminal 119 is constituted by the tab group 65 and the negative electrode conductive member 64 connected in series in this order.

  As shown in FIG. 1, the first positive electrode conductive member 13 is connected in series between the current interrupt device 2 and the second positive electrode conductive member 68, and is fixed to each other by welding. The second positive electrode conductive member 68 is a flat conductive member. The second positive electrode conductive member 68 extends substantially parallel to the upper end surface of the case 1 toward the positive electrode external terminal 19. The second positive electrode conductive member 68 is fixed to the tab group 67 by welding. The current interrupt device 2 is fixed to the positive external terminal 19 on the upper surface side. The positive external terminal 19 and the first positive electrode conductive member 13 are electrically connected via the current interrupt device 2. Thus, the positive electrode energization path from the positive electrode of the electrode assembly 60 to the positive electrode external terminal 19 has a tab group 67, a second positive electrode conductive member 68, and a first positive electrode conductive member connected in series in this order. 13 and the current interrupting device 2. That is, the positive electrode external terminal 19 and the negative electrode external terminal 119 can exchange electricity with the electrode assembly 60. An insulating member 66 is provided between the negative electrode conductive member 64, the first positive electrode conductive member 13, the second positive electrode conductive member 68, and the upper end surface of the case 1, thereby the negative electrode conductive member. 64, the first positive electrode conductive member 13 and the second positive electrode conductive member 68 are insulated from the case 1.

  The case 1 is sealed, and when the electrode assembly 60 generates gas, the internal pressure increases. When the case internal pressure exceeds a predetermined level, the current interrupt device 2 is activated, and the energization path between the positive external terminal 19 and the electrode assembly 60 is interrupted.

  FIG. 2 shows a cross-sectional view of the current interrupt device 2. FIG. 2A shows a structure when the positive electrode energizing path is secured, and FIG. 2B shows a structure when the current interrupting device 2 is activated and the positive electrode energizing path is interrupted. FIG. 3 shows an enlarged cross-sectional view of only the current interrupting device. 3A is an enlarged cross-sectional view of the current interrupting device in a state where the positive electrode energizing path is secured, and FIG. 3B is a state where the current interrupting device 2 is activated and the positive electrode energizing path is interrupted. It is an expanded sectional view of the current interruption device. In FIG. 2, only the main parts are denoted by reference numerals in order to help understanding, and the minor parts are denoted by reference numerals in FIG. 3.

  First, the structure of the electric current interruption apparatus 2 is demonstrated, referring FIG. 2 (A) and FIG. 3 (A). The current interrupt device 2 includes a housing 11, a caulking member 20, a sealing lid 7, a contact plate 5, a current plate 4, and a deformation plate 3 as main components. The current interrupting device 2 itself is disposed in the case of the power storage device 100, and the outside of the current interrupting device 2 is at the pressure of the case internal space (space 42). The pressure in the space 42 corresponds to the case internal pressure. The casing of the current interrupt device 2 includes a caulking member 20, a casing 11, and a sealing lid 7. The casing 11 is made of resin and has an insulating property. The caulking member 20 is made of metal, and caulks the housing 11 and seal members 14 and 17, which will be described later, the contact plate 5, the energization plate 4, and the deformation plate 3. The caulking member 20 and the housing 11 are cylindrical, and one end thereof is covered with the sealing lid 7 and the other end is covered with the deformation plate 3. The inside of the housing 11 is isolated from the case internal space (space 42), and the internal space of the housing 11 (the spaces indicated by reference numerals 43, 44, and 45) is not affected by the internal pressure of the case.

  The sealing lid 7 is made of a conductive metal. A through hole in which a thread groove is formed is provided at substantially the center of the sealing lid 7, and the lower end of the positive electrode external terminal 19 is screwed into this through hole. The upper end of the positive external terminal 19 is exposed to the outside of the case 1. The sealing lid 7 is positioned in the immediate vicinity of the back side of the wall surface of the case 1 of the power storage device 100, and the sealing member 10 is disposed between the inner surface of the case 1. Sealing of the case internal space (space 42) is ensured by the seal member 10.

  Between the sealing lid 7 and the deformation plate 3, the contact plate 5 and the energization plate 4 are sandwiched. The contact plate 5 and the energizing plate 4 are supported by the housing 11 together with the sealing lid 7 and the deformation plate 3, and the inner case thereof is clamped by a metal caulking member 20 to be stopped. The contact plate 5 and the deformation plate 3 are made of metal and have a disk shape, and the periphery of the disk is fixed to the housing 11.

  The contact plate 5 has conductivity and is in contact with the lower end of the sealing lid 7. Therefore, the positive electrode external terminal 19 and the sealing lid 7 and the contact plate 5 are electrically connected. A seal member 17 is attached to the periphery of the contact plate 5 on the side opposite to the sealing lid 7, and a metal energizing plate 4 is attached with the seal member 17 interposed therebetween. The periphery of the energization plate 4 is insulated from the contact plate 5.

  The energization plate 4 has a plate shape and is electrically connected to the first positive electrode conductive member 13. Alternatively, the energization plate 4 and the first positive electrode conductive member 13 are one member. The energization plate 4 has a circular portion that is a portion overlapping the deformation plate 3 and the contact plate 5. The first positive electrode conductive member 13 is electrically connected to the electrode assembly 60 via the second positive electrode conductive member 68. In other words, the energization plate 4 is electrically connected to the electrode assembly 60.

  Normally, the contact plate 5 and the energizing plate 4 are in contact with each other, and both are electrically connected. Specifically, the contact plate 5 includes a protrusion 23 on the side facing the energization plate 4, and the tip surface of the protrusion 23 is in contact with the energization plate 4. When the contact plate 5 and the energizing plate 4 are electrically connected, the electrode assembly 60 and the positive external terminal 19 are electrically connected. The contact plate 5 and the energization plate 4 form a part of the energization path between the electrode assembly 60 and the positive external terminal 19.

  The contact plate 5 includes a protrusion 23, a base flange 24 provided around the base of the protrusion, and a diaphragm 25 continuous with the periphery of the base flange 24 (FIG. 3A). reference). In other words, the base flange portion 24 is a plate portion connected to the base portion of the protrusion 23. As well shown in FIG. 3A, in the cross section perpendicular to the tip surface of the protrusion 23 (in the cross section of FIG. 3), the side surface of the protrusion 23 and the base flange portion 24 are at an acute angle Ag. It is continuous. The contact plate 5 is circular when viewed from a direction perpendicular to the tip surface of the protrusion 23, and the protrusion 23 is also circular when viewed from a direction perpendicular to the tip surface. In other words, the protrusion 23 is cylindrical. Accordingly, the base portion of the protrusion 23 and the base flange portion 24 are connected at an angle Ag anywhere in the circumferential direction of the protrusion 23.

  A diaphragm portion 25 continues to the periphery of the base flange portion 24. The diaphragm portion 25 has a mortar shape whose center protrudes toward the energizing plate 4, and the periphery thereof is supported by the housing 11. The protrusion 23 and the base flange 24 described above are located in the center of the diaphragm 25. The periphery of the diaphragm portion 25 is fixed to the housing 11 so as to jump in a direction perpendicular to the plate and cause buckling. “Jumping buckling” is as previously introduced.

  The diaphragm portion 25 is deformed by jumping and buckling, but the protrusion 23 and the base flange portion 24 are moved with the deformation of the diaphragm portion 25. FIG. 3B shows a state after the projection 23 receives a load and the diaphragm 25 is deformed. For the sake of explanation, the contact plate and the diaphragm before deformation are denoted by reference numerals 5a and 25a, respectively, and the contact plate and the diaphragm after deformation are denoted by numerals 5b and 25b, respectively. When referring to the contact plate and the diaphragm portion regardless of before and after the deformation, they are referred to as the contact plate 5 and the diaphragm portion 25, respectively.

  The front end surface of the protrusion 23 of the contact plate 5 is joined (for example, welded) to the fracture portion 6 of the energizing plate 4. The rupture portion 6 is surrounded by a rupture groove 16, and the rupture groove 16 partitions the energizing plate 4 into the rupture portion 6 and other regions. The breaking groove 16 is a portion whose strength is weaker than other portions of the energization plate so that the breaking portion 6 breaks when receiving an impact.

  The deformation plate 3 is attached to the other end of the housing 11 (the end opposite to the end to which the sealing lid 7 is attached). The deformation plate 3 is adjacent to the energization plate 4 through the seal member 14. In other words, the deformation plate 3 faces the energization plate 4 on the side opposite to the side where the contact plate 5 exists. The deformation plate 3 is made of metal, but is insulated from the energization plate 4 by the seal member 14. As shown in FIGS. 2 (A) and 3 (A), the deformable plate 3 has a mortar shape protruding in a direction away from the energizing plate 4 as an initial shape. A punching projection 12 is provided so as to face the fracture portion 6 of the energization plate 4 at the approximate center of the deformation plate 3. The punching protrusion 12 is made of an insulator (for example, resin).

  Similar to the contact plate 5, the deformation plate 3 has a peripheral edge fixed to the housing 11 so as to jump and buckle. The punching protrusion 12 is positioned away from the fracture portion 6 when the deformable plate 3 is in a mortar shape in a direction away from the energizing plate 4, but the deformable plate 3 jumps and buckles to the energizing plate 4. When it is deformed into a mortar-like shape projecting toward it, it is in a positional relationship where it collides with the fracture portion 6.

  FIG. 3B shows a state after the deformed plate 3 is deformed by jumping and buckling when a load exceeding a predetermined threshold load (case internal pressure exceeding a predetermined level) is applied. . For the sake of explanation, the deformation plate before deformation is represented by reference numeral 3a, and the deformation plate after deformation is represented by reference numeral 3b. When the deformation plate is referred to regardless of before and after the deformation, the deformation plate 3 is described.

  A mechanism by which the current interrupting device 2 interrupts the energization path will be described. One surface of the deformable plate 3 faces the internal space (space 42) of the case 1, and the other surface faces the current interrupting device internal space 43 where the energizing plate 4 exists, and the space 42. And space 43 is partitioned. The space 43 is not affected by the case internal pressure. In other words, the deformation plate 3 faces the first space (case internal space 42) maintained at the same pressure as the case internal pressure, and the other surface is the case internal space 42. This corresponds to facing the energization plate 4 in the isolated second space (current interrupter internal space 43). In the initial state, the deformable plate 3 has a mortar shape that protrudes toward the case internal space 42. In addition, a punching protrusion 12 that protrudes toward the fracture portion 6 is provided at the center of the deformable plate 3. The deformation plate 3 is fixed to the casing 11 at the periphery, and when the internal pressure of the case reaches a predetermined level, the deformed plate 3 protrudes from the mortar shape that protrudes toward the case internal space 42 to the current interrupter internal space 43 side. It jumps into a mortar shape and causes buckling. At that time, the punching protrusion 12 collides with the breakage portion 6 to break the breakage portion 6. In FIG. 3B, the deformed plate 3b before being deformed is drawn with imaginary lines.

  The load that the punching projection 12 gives to the fracture portion 6 is a result of adding a case internal pressure received by the deformable plate 3 and a pressure difference between the current interrupting device internal space 43 and an impact caused by the collision of the punching projection 12. The load caused by the impact when the object collides is much larger than the load caused by the pressure difference, and the fracture portion 6 is reliably broken by the pressure difference and the impact.

  When the deformable plate 3 jumps and buckles and the fracture portion 6 breaks, the contact plate 5 also jumps and buckles due to the momentum, and deforms into a mortar shape protruding in a direction away from the energizing plate 4. The fracture portion 6 is sandwiched between the punching projection 12 of the deformation plate 3 and the projection 23 of the contact plate 5 and is held away from the remaining portion of the energization plate 4. As described above, since the fracture portion 6 is joined to the tip surface of the projection 23 of the contact plate 5, the fracture portion 6 is separated from the projection 23 of the contact plate 5 by the impact of the collision of the punching projection 12. Never leave.

  In FIG. 3B, the angle formed by the deformed plate 3a in the initial state with respect to the plane including the periphery of the deformed plate 3 is indicated by the reference symbol Ad1, and the angle formed by the deformed plate 3b after jumping and buckling is shown. This is indicated by the symbol Ad2. The angles Ad1 and Ad2 have substantially the same absolute value, but are opposite to each other with respect to the plane including the peripheral edge of the deformable plate 3. In FIG. 3B, an angle formed by the contact plate 5a in the initial state with respect to a plane including the peripheral edge of the contact plate 5 is indicated by reference numeral Ae1, and the contact plate 5b after the jump buckling is formed. The angle is indicated by Ae2. The angles Ae1 and Ae2 have almost the same absolute value, but are opposite to each other with respect to the plane including the peripheral edge of the contact plate 5. In the current interrupt device 2, the deformation plate 3 and the contact plate 5 hold the angles Ad1 and Ae1 until the internal pressure of the case reaches a predetermined level. The projecting direction of the mortar shape is reversed at a stretch so as to be respectively Ad2 and Ae2. Once the case internal pressure exceeds a predetermined level, even if the case internal pressure decreases, the deformable plate 3 and the contact plate 5 retain the angles Ad2 and Ae2, respectively, and do not return to their original shapes. Due to such characteristics of jump buckling, once the deformable plate 3 is reversed and the fractured portion 6 is once broken, the fractured portion 6 is held at a position separated from the current-carrying plate 4 and may come into contact with the current-carrying plate 4 again. That is, the possibility that the energization path is re-conducted is suppressed.

  Further, the contact plate 5 is joined to the energizing plate 4 at the front end surface of the central protrusion 23. And the side surface of the protrusion 23 and the base flange portion 24 are continuous at an acute angle (angle Ag). The configuration including the acute angle causes the deformation plate 3 and the contact plate 5 to jump and buckle, the fracture portion 6 breaks, and the electrical connection between the contact plate 5 and the energization plate 4 is interrupted, and then the base flange The possibility that the portion 24 contacts the current-carrying plate 4 is reduced.

  (Second Embodiment) Next, a power storage device according to a second embodiment will be described with reference to FIG. The power storage device according to the second embodiment is different from the power storage device according to the first embodiment in the structure of the current interrupting device, in particular, the mechanism for breaking the breaking portion 6 of the energization plate 204. Structurally, the current interrupt device 202 of the second embodiment differs from the current interrupt device 2 of the first embodiment in that it does not have a deformable plate.

  FIG. 4A shows a structure in a state where the contact plate 5 and the current-carrying plate 204 are electrically connected, that is, in a state where the electrode assembly and the positive external terminal are electrically connected. ) Shows a structure in a state where the electrode assembly and the positive electrode external terminal are electrically disconnected.

  In the current interrupt device 202 of the second embodiment, the shape of the contact plate 5 and the energizing plate 204 is the same as that of the contact plate 5 and the energizing plate 4 of the first embodiment. It is joined to the breaking part 6. This joining is joining with the electroconductivity between the protrusion 23 and the electricity supply board 204, for example, is welding.

  Further, in the current interrupt device 202, the breaking groove 216 that divides the breaking portion 6 and other portions in the energizing plate 204 is formed deeper than the breaking groove 16 in the first embodiment, and the current interruption in the first embodiment is performed. Compared with the device 2, the fracture portion 6 is easily broken. Specifically, in the current interrupt device 202, the energizing plate 204 has a surface opposite to the contact plate 5 facing the case internal space 42, and a surface facing the contact plate 5 is defined as the case internal space. It faces the isolated space (the space 44 in the current interrupt device), and when the internal pressure of the case exceeds a predetermined level, the fracture portion 6 breaks. When the rupture portion 6 breaks, the energization path between the contact plate 5 and the energization plate 204 is interrupted. That is, the energization path between the positive external terminal and the electrode assembly is interrupted.

  FIG. 4A shows a state before breaking, and the contact plate 5 has a mortar shape in which the diaphragm portion 25 is curved toward the energizing plate 204. When the internal pressure of the case rises and the fracture portion 6 breaks, a load is applied to the projection 23 of the contact plate 5 with the momentum of the fracture, and the diaphragm portion 25 is deformed into a shape protruding in a direction away from the energization plate 204. That is, jumping and buckling occurs. Since the breaking portion 6 is joined to the tip surface of the protrusion 23, the breaking portion 6 is separated from the energizing plate 204 together with the tip surface. The deformed shape is shown in FIG. Reference numeral 5a represents a contact plate before jumping and buckling, and reference numeral 5b represents a contact plate after jumping and buckling. Since the deformation of the contact plate 5 from FIG. 4 (A) to FIG. 4 (B) is jumping and buckling, once the deformation is applied, the shape of the contact plate 5 returns to its original shape even if the applied load is removed. Absent. That is, the fracture portion 6 joined to the tip surface of the protrusion 23 of the contact plate 5 is also held at a position spaced from the remaining portion of the energization plate 204.

  Also in the power storage device of the second embodiment, the side surface of the protrusion 23 and the base flange portion 24 are connected with an acute angle. Therefore, when the break portion 6 breaks, the contact plate 5 jumps and reverses due to buckling, and the break portion 6 is at a position away from the remaining portion of the energizing plate 204, the periphery of the break portion 6 (that is, the base flange portion 24). ) Can be prevented from coming into contact with the rest of the current-carrying plate 204 again.

  (Third Embodiment) Next, a power storage device according to a third embodiment will be described with reference to FIG. The power storage device of the third embodiment is also different from the power storage device of the first embodiment in the mechanism for breaking the breaking portion 6 of the energization plate 204, as in the current interrupting device of the second embodiment. Structurally, the current interrupting device 302 of the third embodiment is different from the current interrupting device 2 of the first embodiment in that it does not have a deformation plate and has a through hole 304a in the energizing plate 304.

  The shape of the contact plate 305 is the same as that of the contact plate 5 of the first embodiment. However, in the current interrupt device 302, the tip surface of the protrusion 23 of the contact plate 305 is joined to the fracture portion 6 of the energizing plate 304. This joining is also joining with the electrical conductivity between the protrusion 23 and the electricity supply plate 304, for example, welding. Further, the breaking groove 316 that divides the breaking portion 6 and the other region in the energizing plate 304 is made to be easily broken, as is the breaking groove 216 in the current interrupting device 202 of the second embodiment.

  Since the through hole 304a is provided in the energization plate 304, the space 44 between the energization plate 304 and the contact plate 305 communicates with the case internal space 42 and maintains the same pressure as the case internal pressure. The contact plate 305 defines a space 44 facing one surface and a space 45 facing the other surface (the internal space of the current interrupt device 302 is partitioned, and the space 45 is not subjected to pressure fluctuations in the space 44. When the case internal pressure rises, the pressure in the space 44 becomes higher than the pressure in the space 45, and a load is applied to the diaphragm portion 25 of the contact plate 305. The load is a direction in which the contact plate 305 is separated from the energizing plate 304. When the load exceeds a predetermined threshold load, the fractured portion 6 joined at the front end surface is fractured, and the contact plate 305 jumps into a shape protruding in a direction away from the energizing plate 304 and causes buckling. 5A shows a state before the breaking portion 6 is broken, that is, a state where the positive electrode external terminal and the electrode assembly are electrically connected, and FIG. Positive external terminal and electrode assembly Shows a state in which the current path is interrupted. Code 305a is shows a contact plate of the hopping seat 屈前, code 305b indicates a contact plate of the hopping seat Postbuckling.

  Once the contact plate 305 jumps and buckles, even if the pressure applied to the diaphragm portion 25 is reduced, it does not return to its original shape, and the fracture portion 6 does not come into contact with the remaining portion of the energizing plate 304 again. In addition, since the angle formed by the side surface of the projecting portion of the contact plate 305 and the base flange portion 24 is an acute angle, the possibility that the base flange portion 24 contacts the energizing plate 304 after the fracture portion is broken is small.

  (Fourth Embodiment) Next, a power storage device according to a fourth embodiment will be described with reference to FIG. The current interrupting device 402 of the power storage device of the fourth embodiment differs from the structure of the current interrupting device of the third embodiment in the shape of the base flange portion of the contact plate. The other structure is the same as that of the current interrupt device of the third embodiment. 6A and 6B are also cross-sectional views of the current interrupt device 402. FIG. FIG. 6A shows a state before the breaking portion of the energization plate 304 is broken, that is, a state where an energization path between the positive electrode external terminal and the electrode assembly is secured, and FIG. The state after the fracture | rupture part 6 fractured | ruptured, ie, the electricity supply path | route between a positive electrode external terminal and an electrode assembly is interrupted | blocked is shown. Reference numeral 405a indicates a contact plate before deformation, and reference numeral 405b indicates a contact plate after deformation.

  Also in the current interrupt device 402, when the internal pressure of the case rises above a predetermined level, the contact plate 405 breaks the fracture portion 6 to cause jumping and buckling (see FIG. 6B). In the current interrupt device 402, the base flange portion 424 following the base portion of the protrusion 23 of the contact plate 405 is curved in a direction away from the energizing plate 304. This curvature is similar to the base flange portion connected at an acute angle in the first to third embodiments, and after the contact plate 405 jumps and buckles, the base flange portion 424 comes into contact with the energizing plate 304. To reduce the possibility of losing. Therefore, there is a low possibility that the rupture portion 6 breaks and the conduction path between the positive electrode external terminal and the electrode assembly is cut off and then re-conducted.

  Points to be noted regarding the technology described in the embodiments will be described. The contact plate of the fourth embodiment is curved so that the base flange portion 424 protrudes in the direction away from the energizing plate at the base of the side surface of the protrusion. In the power storage devices according to the first to third embodiments, such a contact plate may be used.

  The size, rigidity, and shape of the contact plate or deformed plate that causes jumping buckling are determined so that the total pressure when the “predetermined level of pressure” is applied becomes the “predetermined threshold load”. That is, the “predetermined threshold load” per unit area corresponds to the “predetermined level of pressure”.

  The current interrupting device for a power storage device described in the embodiment has the following characteristics in summary. The current interrupt device is electrically connected to one of the electrode assembly and the external terminal, and is electrically connected to the other of the electrode assembly and the external terminal, and the periphery is fixed. A contact plate disposed opposite to the energizing plate is provided. The contact plate has a mortar shape protruding toward the energizing plate. Moreover, the mortar-shaped center part of a contact plate is comprised by the protrusion which a front end surface contacts with an electricity supply board, and the base flange part provided in the circumference | surroundings of the base of a protrusion. In the cross section perpendicular to the tip end surface of the protrusion, the side surface of the protrusion and the base flange portion form an acute angle. Alternatively, the base flange portion is curved so as to protrude in a direction away from the energizing plate.

  In the power storage device of the example, a break groove surrounding the break portion was provided in the energizing plate of the current interrupt device. Perforations may be used instead of the grooves.

  In the energization interruption device 2 of the embodiment, the angle Ad1 formed by the deformation plate 3a in the initial state with respect to the plane including the periphery of the deformation plate 3 and the angle Ad2 formed by the deformation plate 3b after jumping buckling are absolute values thereof. The sizes are substantially the same, and the directions are opposite to each other with respect to the plane including the peripheral edge of the deformation plate 3. The angle Ae1 formed by the contact plate 5a in the initial state with respect to the plane including the periphery of the contact plate 5 and the angle Ae2 formed by the contact plate 5b after jumping buckling are substantially the same in magnitude. Yes, and opposite directions with respect to the plane including the periphery of the deformable plate 3. This relationship is a typical structural feature that causes jumping and buckling. However, it should be noted that the shape of the deformed plate or the contact plate and the deformed shape may not satisfy the above relationship by devising the structure.

  Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in this specification or the drawings can achieve a plurality of objects at the same time, and has technical usefulness by achieving one of the objects.

1: Case / 2, 202, 302, 402: Current interruption device / 3, 305: Deformation plate / 4, 204, 304, 404: Current supply plate / 5, 405: Contact plate / 6, 316: Breaking portion / 7: Sealing lid / 10: Sealing member / 11: Housing / 12: Punching protrusion / 13: Conductive member for positive electrode / 14: Sealing member / 16: Breaking groove / 17: Sealing member / 9: Positive electrode external terminal / 20: Caulking Member / 23: Projection / 24, 424: Base flange / 25: Diaphragm / 42: Case internal space / 43: Current interrupter internal space / 60: Electrode assembly / 61: Insulation member / 64: Conductive for negative electrode Member / 100: Power storage device

Claims (5)

A case, and an electrode assembly in the case;
An external terminal exposed outside the case;
A power storage device including a current interrupt device that interrupts a current-carrying path between the electrode assembly and the external terminal;
The current interrupt device is
A current-carrying plate electrically connected to one of the electrode assembly and the external terminal;
A protrusion that is electrically connected to the electrode assembly and the other of the external terminals and is disposed to face the current-carrying plate and is electrically connected to the current-carrying plate, and a base flange that is continuous with the base of the protrusion A contact plate having a portion;
With
The contact plate is fixed at both ends or the periphery so that when it receives a load exceeding a predetermined threshold load, it jumps in a direction away from the energizing plate and causes a shape change due to buckling,
The protrusion has a front end surface, and the base flange portion and a side surface of the protrusion form an acute angle in a cross section perpendicular to the front end surface, or the base flange portion is the current plate. Curved to protrude away from the
A power storage device. The energizing plate is provided with a breaking portion that breaks when receiving a load exceeding the threshold load and is separated from the surroundings, and the breaking portion is in contact with the tip surface,
2. The power storage device according to claim 1, wherein the energization plate is electrically connected to one of the electrode assembly and the external terminal except for the fracture portion.   The energizing plate faces the first space where the surface opposite to the contact plate is maintained at the same pressure as the case internal pressure, and the surface facing the contact plate is isolated from the case internal space. 3. The power storage device according to claim 2, wherein the power storage device faces the second space, and the rupture portion breaks when a case internal pressure exceeds a predetermined level.   One surface faces the first space maintained at the same pressure as the case internal pressure, and the other surface faces the current-carrying plate in the second space isolated from the case internal space, The whole has a mortar shape protruding toward the first space side, and a punching protrusion protruding toward the breaking portion is provided at the center, and when the internal pressure of the case reaches a predetermined level, the whole is the second space. The power storage device according to claim 2, further comprising a deforming plate that jumps to a mortar shape protruding sideward and causes buckling to cause a punching projection to collide with the fracture portion.   The contact plate faces the first space where the surface facing the energization plate is maintained at the same pressure as the case internal pressure, and the surface opposite to the energization plate is isolated from the case internal space. The power storage device according to claim 1, wherein the power storage device faces the second space and jumps and buckles when the internal pressure of the case exceeds a predetermined level.

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