JP2014232690A - Current interrupter and power storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a current interrupter in which the possibility of reconduction is reduced.SOLUTION: A current interrupter interrupts an energizing path between an electrode assembly in a case of a power storage device and an external terminal exposed to the outside of the case when the internal pressure of the case exceeds a predetermined level. The current interrupter includes an energizing plate, a contact plate, and a deformation plate. The energizing plate has a fracture part which is fractured upon application of a predetermined load. The contact plate is arranged to face the energizing plate, and conducts with the fracture part. The energizing plate and the contact plate constitute a part of the energizing path. The deformation plate has one surface facing a first space held at the same pressure as the internal pressure, and the other surface facing the energizing plate in a second space separated from the internal space of the case, and also facing the energizing plate. When the internal pressure rises over a predetermined level, the deformation plate deforms to the energizing plate side, and fractures the fracture part by giving a predetermined load. The deformation plate and the contact plate are fixed to a cylindrical support member, and the area of the contact plate is larger than the area of deformation plate.

Description

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

  Power storage devices such as lithium ion batteries, nickel metal hydride batteries, and other secondary batteries (storage batteries) are becoming increasingly important as on-vehicle power supplies or personal computers and portable terminals. In particular, the lithium ion battery is expected to be used as a high output power source for mounting on a vehicle. Lithium ion batteries are lightweight and can provide a high energy density. A typical structure of a secondary battery includes a battery (sealed battery) having a sealed structure in which an electrode assembly and an electrolytic solution are housed in a case and the case is sealed.

  When charging the battery, if the battery is defective or the charging device malfunctions, a current greater than normal may flow through the battery. As a result, the battery may be overcharged. When an abnormality such as an overcharged state occurs in the battery, gas may be generated in the sealed case. The pressure inside the case increases, and the battery (case) may swell or the case may be damaged by the gas pressure. In order to cope with such a problem, a power storage device (battery) including a current interrupt device has been proposed. When the internal pressure of the sealed case rises abnormally, the current interrupt device interrupts the current and ensures the safety of the power storage device. Examples of current interrupting devices are disclosed in Patent Documents 1-6.

JP 09-289010 A Japanese Patent Laid-Open No. 10-241654 Japanese Patent Laid-Open No. 09-036999 JP 09-134715 A Japanese Patent Laid-Open No. 11-224658 JP 2003-331822 A

  Any of the above-described conventional current interrupting devices interrupts the energization path between the electrode assembly and the external terminal due to an increase in the case internal pressure of the storage battery. The inventors have devised a current interrupting device that interrupts the energization path by a mechanism different from the prior art (Japanese Patent Application No. 2012-090992 and PCT / JP2013 / 060968, unpublished at the time of filing this application). The technology has a plate material (a deformed plate, which will be described later) that isolates the portion of the energization path that is cut when the case internal pressure rises from the electrolysis solution, and the plate material has a structure that blocks the current cut-off portion as the case internal pressure rises. ing. Details of the structure will be described in detail in an embodiment of the invention.

  The present specification is a further improvement of the above-described current interrupting device devised by the inventors. The purpose of the present specification is that the energizing path is re-conducted after the energizing path is interrupted due to an increase in the internal pressure of the case. There is more reliably to prevent.

  The current interrupting device disclosed in this specification has the following basic structure and technical features. The internal space of the current interrupt device is isolated from the space inside the case of the power storage device, and the interior of the current interrupt device is not affected by the internal pressure of the case. Deformation in which a part of the partition wall that isolates the inside and outside of the current interrupting device (the space inside the case of the power storage device) is deformed when the case internal pressure (that is, the pressure difference between the inside and outside of the current interrupting device) exceeds a predetermined level It consists of a plate. Although a part of the energization path is exposed in the current interrupting device, since it is isolated from the inside of the case of the power storage device, even if an arc occurs in the energization path, the gas inside the case is not affected. Even when the case is filled with the electrolyte, the internal space of the current interrupt device is isolated from the case internal space, so that the electrolyte is not immersed in the exposed energization path, and the energization path does not deteriorate.

  The current interrupting device also includes two conductive plates constituting an energization path, that is, an energization plate and a contact plate. The energization plate is provided with a breaking portion that breaks when a predetermined load is applied by the above-described predetermined level of internal pressure and moves in the pressure receiving direction of the case internal pressure. The contact plate is disposed to face the energizing plate. Further, the contact plate is electrically connected to the fracture portion. The energization path between the electrode assembly and the external terminal passes through the energization plate and the contact plate in order from the electrode assembly to the external terminal. Alternatively, the energization path passes through the contact plate and the energization plate in order from the electrode assembly to the external terminal.

  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 energizing plate in the second space isolated from the internal space of the case. And it is arrange | positioned with respect to the electricity supply board on the opposite side to a contact plate. The above-mentioned “pressure receiving direction” is a direction in which the deformable plate receives the case internal pressure, and is a direction from the deformable plate toward the energizing plate. The deformed plate is deformed to the energizing plate side when the case internal pressure rises above a predetermined level, and breaks by applying a predetermined load to the fracture portion. And the deformation | transformation board and the contact plate are being fixed inside the cylindrical support member.

  In the current interrupt device disclosed in the present specification, the area of the contact plate is smaller than the area of the deformed plate. Therefore, the bending rigidity related to the out-of-plane deformation of the contact plate can be reduced. More specifically, the bending rigidity in the out-of-plane direction of the contact plate can be made smaller than the bending rigidity in the out-of-plane direction of the deforming plate. After the deformable plate is deformed and breaks the fractured portion, the deformable plate further pushes the broken portion together with the contact plate in the pressure receiving direction to separate from the remaining portion of the energizing plate. By satisfy | filling said relationship, the force which a contact plate pushes back a deformation | transformation board after breaking a fracture | rupture part can be made small. Therefore, the fractured portion after the fracture is prevented from approaching the remaining portion of the current-carrying plate. As a result, the broken portion or the contact plate after the breakage is prevented from re-conducting with the energizing plate.

  Also, the low bending rigidity in the out-of-plane direction of the contact plate means that the contact plate is pressed together with the fractured portion immediately after the deformed plate collides with the fractured portion. Further ensure the breakage of the part.

  An example of a specific structure in which the area of the contact plate is made smaller than the area of the deformation plate is to provide a hole or notch in the contact plate. When the deformation plate and the contact plate are supported on the inner surface of the cylindrical casing of the current interrupt device, the outer shape of the deformation plate and the contact plate is the same. The area of the plate is smaller than the area of the deformed plate.

  When a hole or a notch is provided in the contact plate, the shape of the contact plate may not be point-symmetric with respect to the center when viewed from the stacking direction of the contact plate and the deformation plate. However, in order for the center of the contact plate (the portion in contact with the fractured portion) to be smoothly deformed in the out-of-plane direction as the deformed plate is deformed, the contact plate is It is preferably point-symmetric.

  In addition, the deformation plate is formed in a mortar shape that protrudes toward the first space, and jumps to a mortar shape that protrudes toward the second space when the internal pressure of the case rises above a predetermined level. It is preferable to cause deformation by buckling. Here, the deformation plate having a “mortar shape” means that a cross section passing through the center of the deformation plate has a mortar shape.

  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, A phenomenon that momentarily discontinuous deformation occurs so that the bending direction of the plate material suddenly reverses from one side to the other when it exceeds a predetermined size, and the reversed shape does not return to its original state even if the load is removed. Say. The shape causing jumping and buckling is the above-mentioned mortar shape.

  When the deformed plate jumps and buckles and deforms, after the jump buckling occurs and the fractured portion is broken, the deformed plate does not return to its original shape even if the internal pressure of the case decreases. Therefore, even if the internal pressure of the case is reduced, the possibility that the fractured part approaches the original position and contacts the remaining part of the energizing plate to cause re-conduction can be reduced.

  In order to break the breakage portion more reliably, a punching protrusion that protrudes toward the breakage portion may be provided at the center of the deformable plate. In this case, when the case internal pressure is equal to or lower than a predetermined level (when it is the same level as the external pressure), the deformation plate may be arranged so that a gap is provided between the top surface of the punching protrusion and the fracture portion. And when the deforming plate and the energizing plate are arranged so that when the internal pressure of the case rises above a predetermined level, the deforming plate is deformed toward the energizing plate and the punching protrusion collides with the breaking portion and breaks. Good. Furthermore, it is preferable that the deformable plate jumps and causes buckling. In such a configuration, the moving speed of the punching protrusion due to abrupt deformation at the time of jumping buckling is added, and a strong collision can be given to the rupture portion to ensure breakage.

  On the other hand, in order to make it easy to break the breaking portion of the current-carrying plate, a breaking groove or a perforation (perforation) may be provided so as to surround the breaking portion. Grooves and perforations have lower strength than other parts, and the fractured part is easily broken.

  The relationship between the deformed plate having the punching protrusion and the energizing plate having the fracture portion changes as follows. When the case internal pressure is less than a predetermined level, the punching protrusion of the deformed plate is moved from the first state in which a gap is provided between the punching protrusion and the fracture portion when the case internal pressure rises above the predetermined level. , Move toward the energizing plate, apply impact to the fractured part and contact plate and move the fractured part and contact plate away from the energizing plate; The plate shifts to the third state in which the force that separates the contact plate from the energizing plate is balanced. In the third state, the contact plate is kept away from the energizing plate so as not to conduct with the energizing plate. Note that the present specification also provides a novel power storage device including the above-described current interrupt device.

  Details and further improvements of the technology disclosed herein are described in detail in the following examples.

  According to the invention disclosed in this specification, it is possible to more reliably prevent the energization path from re-conducting after the energization path is interrupted due to an increase in the internal pressure of the case.

The longitudinal cross-sectional view of an electrical storage apparatus is shown. About the electric current interruption apparatus of 1st Example, the state at the time of normal is shown. About the electric current interruption apparatus of 1st Example, the state by which the electricity supply path | route was fractured | ruptured is shown. The top view of the contact plate in 1st Example is shown. About the electric current interruption apparatus of 2nd Example, the state at the time of normal is shown. About the electric current interruption apparatus of 2nd Example, the state by which the electricity supply path | route was fractured | ruptured is shown. The top view of the contact plate in 2nd Example is shown. About the electric current interruption apparatus of 3rd Example, the state at the time of normal is shown. About the electric current interruption apparatus of 3rd Example, the state immediately after a conduction path is fractured | ruptured is shown. About the electric current interruption apparatus of 3rd Example, the state after the energization path | route was fractured | ruptured and predetermined time passed is shown.

  Examples of the current interrupting device disclosed in this specification will be described below. Note that in the power storage device disclosed in this specification, various configurations other than the current interrupt device 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 As shown in FIG. 1, the power storage device 100 includes a case 1, an electrode assembly 60, a negative external terminal 19, a positive external terminal 119, and a current interrupt device 2. The case 1 includes a rectangular box-shaped main body portion 62 and a rectangular flat plate-shaped lid portion 63 that closes the main body portion 62. The main body portion 62 and the lid portion 63 are made of metal (for example, stainless steel or aluminum). In the following description, the main body portion 62 and the lid portion 63 may be simply referred to as the case 1. Inside the case 1 is accommodated an electrode assembly 60 including a positive electrode and a negative electrode. Case 1 and electrode assembly 60 are insulated by insulating sheet 61. A positive current collecting tab 65 is fixed to the positive electrode. A negative electrode current collecting tab 67 is fixed to the negative electrode.

  The negative external terminal 19 and the positive external terminal 119 are fixed to the case 1 (lid portion 63). Although illustration is omitted, the negative external terminal 19 and the case 1 and the positive external terminal 119 and the case 1 are insulated by an insulating sheet or the like. The negative external terminal 19 is electrically connected to the negative current collecting tab 67 (negative electrode) via the current interrupt device 2 and the negative electrode lead 68. Details of the current interrupt device 2 will be described later. In addition, the electric current interruption apparatus 2 and the negative electrode lead 68 are connected by the connection member 13 which has electroconductivity. The positive external terminal 119 is electrically connected to the positive current collecting tab 65 (positive electrode) via the positive lead 64. The negative electrode lead 68 and the positive electrode lead 64 are insulated from the case 1 by an insulating sheet 66 attached to the case 1 (lid portion 63).

  With reference to FIG. 2A and 2B, the electric current interruption apparatus 2 of 1st Example is demonstrated. 2A and 2B, an electrode assembly 60 (see FIG. 1) including a positive electrode and a negative electrode is not shown. The electrode assembly 60 is disposed below FIGS. 2A and 2B. The current interrupt device 2 electrically connects the electrode assembly 60 and the negative electrode external terminal 19. The current interrupt device 2 prevents gas from flowing between the inside of the case 1 in which the electrode assembly 60 is accommodated and the outside of the case 1. The current interrupt device 2 interrupts the energization path between the electrode assembly 60 and the negative external terminal 19 when the internal pressure in the case 1 rises above a predetermined level. 2A and 2B, illustration of the insulating sheet 66 interposed between the negative electrode external terminal 19 and the case 1 is omitted.

  The above-mentioned “predetermined level of internal pressure” refers to the internal pressure of case 1 when power storage device 100 is in an overcharged (overvoltage) state or power storage device 100 is in an overheated state (thermal runaway temperature of the active material). Means. The “predetermined level of internal pressure” is determined by conditions such as the capacity of the power storage device 100 and the output voltage. In the power storage device 100, the current interrupt device 2 is disposed below the negative external terminal 19. However, the position where the current interrupt device 2 is arranged is not limited to the position below the negative electrode external terminal 19. The current interrupting device 2 only needs to be disposed on a series current path between the electrode assembly 60 and the negative electrode external terminal 19.

  The current interrupt device 2 is disposed inside the case 1 of the power storage device 100 and is sealed so that gas inside the case 1 (outside the current interrupt device 2) does not flow inside the current interrupt device 2 ( Sealed). Since the outer space (space 91) of the current interrupt device 2 is a case internal space, its pressure is the same as the internal pressure of the case. Since the current interruption device 2 is sealed, the internal pressure of the case 1 does not affect the internal space (space 92). Therefore, when the internal pressure of the case 1 increases, the pressure difference increases inside and outside the current interrupt device 2, and when the internal pressure exceeds a predetermined level, the energization path is interrupted by the pressure difference.

  The structure of the current interrupt device 2 will be described in order from the inside of the case 1 of the power storage device 100 (downward in FIG. 2A) to the outside of the case 1 (upward in FIG. 2A). The current interrupt device 2 includes a deformation plate 3, a current supply plate 4, and a contact plate 5. 2A and 2B are cross-sectional views, but the deformation plate 3 and the contact plate 5 have a disk shape, and are the same when viewed from any direction within the XY plane of the coordinate system in the drawing.

  The deformation plate 3 is a thin plate. Specifically, the deformable plate 3 is a metallic diaphragm. One surface of the deformable plate 3 faces the space 91 (that is, the case internal space), and the other surface faces the space 92 (that is, the internal space of the current interrupting device 2). The outer periphery of the deformable plate 3 is fixed to the cylindrical casing 11 via the seal member 14. The deformation plate 3 constitutes a part of a partition that separates the space 91 and the space 92. As described above, since the space 92 is not affected by the pressure of the space 91 (the space held at the case internal pressure), when the case internal pressure rises, a pressure difference is generated on both sides of the deformable plate 3. The deformation plate 3 is deformed by the pressure difference.

  As shown in FIG. 2A, the deformable plate 3 has a mortar shape projecting toward the space 91 (a mortar shape projecting toward the space 91), and has a punching protrusion at the center thereof so as to face the energizing plate 4. A portion 12 is provided. More specifically, the punching protrusion 12 is provided so as to face a fracture portion 6 (described later) that is a part of the energization plate 4. The punching protrusion 12 is made of an insulating material. The shape of the punching protrusion 12 is, for example, a cylindrical shape.

  The energization plate 4 is located above the deformation plate 3 in the drawing. In other words, the energization plate 4 is disposed so as to face the deformation plate 3. The energization plate 4 is also a metal plate, and the periphery thereof is fixed to the housing 11. The current-carrying plate 4 has conductivity, and is electrically connected to the electrode assembly 60 via the conductive connection member 13, the negative electrode lead 68 (see FIG. 1), and the negative electrode current collecting tab 67 (see FIG. 1). Has been. The connection member 13 may be integral with the current supply plate 4. The energization plate 4 has a circular portion that overlaps (stacks) with the deformation plate 3 and the contact plate 5. The central portion 15 of the current plate 4 (the portion included in the above-described circular portion) is thinner than the other portions of the current plate 4. At the center portion 15, a fracture portion 6 is provided. A fracture groove 16 is formed so as to surround the fracture portion 6. In other words, the fracture portion 6 and the other region are defined by the fracture groove 16. The fracture groove 16 is made more fragile than other parts. When the fracture portion 6 receives an impact, the fracture portion 6 breaks along the fracture groove 16.

  A contact plate 5 is arranged on the side opposite to the deformation plate 3 with the energization plate 4 interposed therebetween. In other words, the deformable plate 3 is disposed on the opposite side of the contact plate 5 with respect to the energizing plate 4. As described above, the deformable plate 3, the energizing plate 4, and the contact plate 5 are stacked in this order. The direction in which the deformable plate 3, the current plate 4 and the contact plate 5 are stacked corresponds to the “stacking direction” in the claims. The contact plate 5 is also a metal disc, and the casing 11 supports the peripheral edge thereof. A seal member 17 is disposed between the contact plate 5 and the energizing plate 4 at the periphery thereof, and the contact plate 5 and the energizing plate 4 are insulated at the periphery. The contact plate 5 has a mortar shape whose center protrudes toward the energizing plate 4, and is joined to the breaking portion 6 of the energizing plate 4 at the center, and is electrically connected to the energizing plate 4 through the breaking portion 6. In other words, the contact plate 5 and the energizing plate 4 are not conductive except at the broken portion 6. The planar shape of the contact plate 5 will be described later.

  The energization plate 4 has a plate shape and is electrically connected to the negative electrode external terminal 19 through a conductive sealing lid 7 described later. After all, the negative electrode external terminal 19 is connected to the electrode via the sealing lid 7, the contact plate 5, the current plate 4, the connection terminal member, the negative electrode lead 68 (see FIG. 1), and the negative electrode current collecting tab 67 (see FIG. 1). The assembly 60 is in conduction. That is, the above path corresponds to the energization path. In FIG. 2A, a thick line indicated by reference numeral 21 represents an energization path. As will be described in detail later, when the fracture portion 6 breaks and the electrical connection between the contact plate 5 and the current plate 4 is interrupted, the current path between the negative electrode external terminal 19 and the electrode assembly 60 is interrupted. . The energization path may be a path from the electrode assembly 60 in order to the negative electrode external terminal 19 through the energization plate 4 and the contact plate 5, or conversely, from the electrode assembly 60 in order. A path that passes through the current-carrying plate 4 and reaches the negative external terminal 19 may be used.

  The upper end of the cylindrical casing 11 is sealed with a sealing lid 7. An outer peripheral portion of the sealing lid 7 is supported by an insulating casing 11. As described above, the outer peripheral portion of the sealing lid 7 is in contact with the contact plate 5 and is electrically connected to the contact plate 5. On the inner surface (surface on the contact plate 5 side) of the sealing lid 7, a recess 18 is provided that is recessed upward (on the side away from the contact plate 5). Specifically, the central portion of the sealing lid 7 is recessed above the outer peripheral portion (portion in contact with the contact plate 5) of the sealing lid 7. When the punching protrusion 12 of the deformation plate 3 comes into contact with the energizing plate 4, the contact plate 5 is deformed upward. The recess 18 is a space for allowing the contact plate 5 to be deformed upward.

  The deformation plate 3, the current supply plate 4, the contact plate 5, and the sealing lid 7 are all fixed to a cylindrical housing 11. The housing 11 has insulating properties, and is formed by, for example, a resin mold. When the housing 11 is viewed in plan, it has a ring shape. Here, the plan view corresponds to a viewpoint in the Z-axis direction in the coordinate system in the drawing. Small flanges are provided at both ends of the cylindrical casing 11, and the deformation plate 3, the current supply plate 4, the contact plate 5, and the sealing lid 7 are disposed between the flanges. The flanges on the inner circumferences of both ends of the casing 11 receive a compressive force in the cylindrical axial direction of the casing 11 by a caulking member 20 that covers the casing 11 from the outside. The deformation plate 3, the current supply plate 4, the contact plate 5, and the sealing lid 7 are held by the axial compressive force.

  The internal space 92 of the current interrupt device 2 is isolated from the internal space 91 by the housing 11, the sealing lid 7, and the deformation plate 3. Therefore, even if the in-case space 91 is filled with the electrolytic solution, the energizing plate 4 and the contact plate 5 do not have to be immersed in the electrolytic solution. By protecting the current-carrying plate 4 and the contact plate 5 from the electrolytic solution, their deterioration is suppressed.

  The operation of the current interrupt device 2 will be described. For example, when the power storage device 100 is overcharged, gas is generated inside the sealed case 1 and the internal pressure of the case 1 increases. The pressure in the space indicated by reference numeral 91 increases. Since the space indicated by reference numeral 92, that is, the internal space of the current interrupt device 2 is not affected by the internal pressure of the case, a pressure difference is generated on both sides of the deformation plate 3. The mortar-shaped deformable plate 3 whose center is convex toward the space 91 causes jumping buckling and protruding toward the space 92 when the pressure on the space 91 side (that is, the case internal pressure) exceeds a predetermined level. Transforms into In other words, the deformable plate 3 is deformed from a mortar shape whose center is convex toward the space 91 to a mortar shape whose center is convex toward the space 92. The deformable plate 3 and the energizing plate 4 are arranged in a positional relationship in which a gap exists between the top surface 24 of the punching protrusion 12 and the fracture portion 6 in the initial shape of the deformable plate 3. Further, the deforming plate 3 and the energizing plate 4 are arranged in a positional relationship in which the punching protrusion 12 penetrates the energizing plate 4 when the deforming plate 3 is deformed.

  Since the shape change due to jumping buckling occurs instantaneously, the punching projection 12 moves toward the fracture portion 6 at a high speed. When the punching protrusion 12 collides with the fracture portion 6, an impact force is applied to the pressure difference between both sides of the deformable plate 3, and the fracture portion 6 is fractured from the current plate 4 by both the pressure difference and the impact force. Separate from. Note that the fracture of the fracture portion 6 occurs from the fracture groove 16. The breakage portion 6 breaks, and the breakage portion 6 and the contact plate 5 are separated from the remaining portion of the energization plate 4, whereby the contact between the contact plate 5 and the energization plate 4 is interrupted. That is, the energization path between the negative external terminal 19 and the electrode assembly 60 is interrupted.

  In other words, the above operation is as follows. That is, the breaking portion 6 breaks and moves in the pressure receiving direction of the case internal pressure when a predetermined load is applied by the case internal pressure at a predetermined level. Here, the predetermined load is caused by the punching protrusion 12 of the deformation plate 6. The “pressure receiving direction” is a direction in which the case internal pressure presses the deformation plate 6, and this direction corresponds to a direction in which the punching protrusion 12 of the deformation plate 6 moves due to the deformation of the deformation plate 6.

  As shown in FIG. 2B, in the shape of the deformed plate 3 after jumping and buckling, the top surface of the punching protrusion 12 passes through the energizing plate 4 and protrudes to the opposite side of the deformed plate. Once deformation due to jumping and buckling occurs, even if the load causing the deformation disappears, it does not return to its original shape. Therefore, the fracture portion 6 and the contact plate 5 are kept away from the remaining portion of the energization plate 4 so as to be pushed out by the punching protrusion 12. The contact plate 5 or the broken portion 6 is prevented from coming into contact with the remaining portion of the energizing plate 4 again.

  In the current interrupting device 2 described above, when the case internal pressure exceeds a predetermined level, the deformed plate jumps and buckles and deforms. The deformation of the jumping buckling occurs instantaneously, and in the current interrupting device 2, the moment of deformation of the deformation plate 3 is added to the pressure difference between both surfaces of the deformation plate 3 to break the fracture portion. Therefore, even when the case internal pressure gradually increases, the current path can be reliably broken at a specific constant internal pressure level (the predetermined level described above).

  Further, in the current interrupt device 2, the junction between the energizing plate 4 and the contact plate 5 is exposed in the internal space. On the other hand, the deformation plate 3 functions as a part of a mechanism for cutting off the energization path and constitutes a part of a partition wall between the space inside the case of the power storage device and the internal space of the current interruption device 2. Therefore, even if the inside of the case is filled with the electrolytic solution, the junction between the energizing plate 4 and the contact plate 5 does not touch the electrolytic solution.

  The planar shape of the contact plate 5 and its advantages will be described. FIG. 3 shows a plan view of the contact plate 5. FIG. 3 also shows a cross section of the casing 11 and the caulking member 20. Since the casing 11 and the crimping member 20 are cylindrical, the casing 11 and the crimping member 20 appear as a ring-shaped cross section in FIG. 3. Note that reference numeral 11 a indicates the inner surface of the housing 11.

  The outer shape of the contact plate 5 is also circular. The outer shape of the contact plate 5 is represented by a circle indicated by reference numeral 11a in FIG. Further, the periphery of the contact plate 5 is fixed to the housing 11. The contact plate 5 is provided with four holes HL. The four holes HL are provided at equal intervals in the circumferential direction of the contact plate 5. As a result, in the plan view of FIG. 3, the shape of the contact plate 5 is point-symmetric with respect to the center CL of the outer circular shape. is there.

  The contact plate 5 and the deformation plate 3 are made of metal plates having the same characteristics and the same thickness, and both are fixed to the inside of the same cylindrical casing 11 and have the same outer shape. The plate 3 has no holes or notches, and the contact plate 5 has holes HL. In other words, the area of the contact plate 5 is smaller than the area of the deformation plate 3 by the area of the hole HL. Since the contact plate 5 has the four holes HL, the bending rigidity of the deformation in the out-of-plane direction is lower than the bending rigidity of the deformation plate 3 in the out-of-plane direction. The contact plate 5 has a smaller area when viewed in plan than the area of the deformable plate 3, and a bending rigidity against out-of-plane deformation is lower than that of the deformable plate 3. Therefore, as shown in FIG. 2B, after the deformable plate 3 is deformed and the fractured portion 6 is broken, the force to push the deformable plate 3 back toward the original shape, that is, the energizing plate 4 is small. This means that the possibility that the energized path once interrupted is re-conductive is small.

  Further, the fact that the bending rigidity in the out-of-plane direction of the contact plate 5 is lower than that of the deformable plate 3 means that immediately after the deformable plate 3 collides with the broken portion 6, the contact plate 5 is pushed up together with the broken portion 6. In addition, the contact plate 5 is easily displaced, and the fracture of the fracture portion 6 is further ensured.

  Further, since the planar shape of the contact plate 5 having holes is point-symmetric with respect to the center CL, when the contact plate 5 is deformed in the out-of-plane direction with the movement of the punching protrusion 12, the center portion is It is easy to deform straight in a direction perpendicular to the surface of the plate 5.

  (Second Embodiment) Next, a current interrupting device according to a second embodiment will be described with reference to FIGS. 4A, 4B and 5. FIG. The power storage device 200 will be described. The power storage device 200 is a modification of the power storage device 100, and the structure of the current interrupt device 202 of the third embodiment is different from the current interrupt device 2 of the power storage device 100. The same members as those of the power storage device 100 are denoted by the same reference numerals as those of the power storage device 100, and the description thereof may be omitted. 4A shows a state before the energization path is broken, and FIG. 4B shows a state after the energization path is broken. FIG. 5 shows a plan view of the contact plate 105. In the following embodiments, the entire power storage device is not shown, and only the structure around the current interrupting device may be shown. Also in FIG. 4A, the thick line indicated by reference numeral 21 represents the energization path. The energization path is the same as that of the first embodiment shown in FIG. 2A.

  In the current interrupt device 202, the deformation plate 25 is formed of a thin plate having an arcuate corrugated portion. However, the center part of the deformation | transformation board 25 is flat form. The corrugated part is provided between the central part and the outer peripheral part.

  After the breaking portion 6 of the current plate 4 is broken, it is preferable that the distance between the broken portion 6 that has moved and the remaining portion of the current plate 4 is large. When the deformable plate is flat, in order to increase the distance between the energizing plate 4 and the fractured portion 6, the deformable plate is attached to the electrode assembly 60 before the deformable plate is deformed (when the internal pressure of the case 1 is normal). It is necessary to protrude largely to the side. However, if the space for attaching the current interrupt device is small, the deformable plate cannot be protruded largely toward the electrode assembly 60 side. Therefore, when the deformable plate jumps and deforms due to buckling, the displacement amount (stroke) of the central portion of the deformable plate does not increase. If the distance between the current-carrying plate 4 and the fractured portion 6 after fracture can be increased, the reliability of the current interrupting device (not to re-energize the current-carrying path) can be improved.

  In the current interrupt device 202, the corrugated portion is provided on the deformation plate 25. Therefore, in the direction in which the deformation plate 25 is displaced (Z-axis direction in the coordinate system in FIGS. 4A and 4B), even if the space for attaching the current interrupt device 202 is small, a sufficient amount of displacement of the deformation plate 25 is ensured. be able to. That is, the deformation amount of the deformation plate 25 can be increased in the direction in which the deformation plate 25 is displaced, and the stroke of the deformation plate 25 can be increased. In the case of the deformable plate 25 provided with the corrugated portion, it is desirable that the deformable plate 25 has a structure that causes jump buckling. However, the deformation plate 25 is not deformed due to jump buckling, but with an increase in the internal pressure of the case. The structure may be gradually deformed. In the case of a structure in which the deformable plate 25 does not jump and cause buckling, it is preferable that the contact plate 5 has a structure that causes deformation due to the jumping and buckling.

  FIG. 5 shows a plan view of the contact plate 105. 5 also shows a cross section of the casing 11 and the caulking member 20 as in FIG. The casing 11 and the crimping member 20 are cylindrical. Reference numeral 11 a indicates the inner surface of the housing 11.

  The contact plate 105 has four notches HC. The four notches HC are provided at point-symmetrical positions with respect to the center CL of the contact plate 105. Therefore, the outer shape of the contact plate 105 is a cross when viewed in a plan view of FIG. The area of the contact plate 105 is also smaller than the area of the deformation plate 25 by the area of the four notches HC. This shape of the contact plate 105 has the same advantages as the contact plate 5 of the first embodiment.

  (Third Embodiment) A power storage device 300 will be described with reference to FIGS. 6A, 6B and 6C. The power storage device 300 is a modification of the power storage device 100, and the structure of the current interrupt device 302 of the third embodiment is different from the current interrupt device 2 of the power storage device 100. The same members as those of the power storage device 100 are denoted by the same reference numerals as those of the power storage device 100, and the description thereof may be omitted. 6A shows a state before the energization path is broken, FIG. 6B shows a state immediately after the energization path is broken, and FIG. 6C shows a state after a predetermined time has elapsed since the energization path is broken.

  The form of the parts constituting the current interrupt device 302 is the same as that of the current interrupt device 2. In the current interrupt device 302, the materials and dimensions of the deformation plate 3 and the contact plate 5 are adjusted so as to operate in the order of FIGS. 6A, 6B, and 6C. As shown in FIG. 6A, when the internal pressure of the case 1 is less than a predetermined level, a series energization path from the electrode assembly 60 (see FIG. 1) to the negative external terminal 19 is formed. At this time, a gap exists between the end surface of the deformable plate 3 on the current plate 4 side (the surface facing the head plate 24 and the current plate 4 of the punching protrusion 12) and the current plate 4 (first state). ).

  As shown in FIG. 6B, when gas is generated inside the case 1 and the internal pressure of the case 1 exceeds a predetermined level, the deformable plate 3 has a mortar shape whose center projects toward the case internal space (space 91). It deforms into a mortar shape protruding toward the current-carrying plate 4. The deformation at this time is caused by jumping and buckling and occurs instantaneously. Then, the punching projection 12 collides with the fracture portion 6 of the energizing plate 4 during deformation. Due to the impact of the collision, the fracture portion 6 breaks starting from the fracture groove 16. As a result of the deformation due to the jumping buckling, the top surface 24 of the punching projection 12 penetrates the energizing plate 4 and projects in the opposite direction. Then, the contact plate 5 is separated from the energizing plate 4 together with the fracture portion 6 of the energizing plate 4 (second state). As a result, the energization path from the electrode assembly 60 (see FIG. 1) to the negative external terminal 19 is interrupted.

  As shown in FIG. 6C, when the energization plate 4 is broken and a predetermined time elapses, the distance between the contact plate 5 and the energization plate 4 becomes shorter than that in the second state (third state). This is because the impact applied to the contact plate 5 from the punching protrusion 12 is eliminated, and a restoring force is generated in the contact plate 5. The contact plate 5 stops at a position where the force by which the contact plate 5 moves toward the energizing plate 4 and the force by which the deformable plate 3 jumps and maintains the shape after buckling is balanced. Note that the planar shape of the contact plate 5 is the shape shown in FIG. 3 or 5, and a hole or notch is provided, and the area thereof is smaller than the area of the deformable plate 3. Therefore, the bending rigidity of the out-of-plane deformation of the contact plate 5, that is, the restoring force is smaller than the bending rigidity of the deformation plate 3. That is, the difference in the position of the breakage portion 6 between the second state and the third state is small, and the breakage portion 6 after the breakage is more reliably prevented from re-conducting with the energization plate 4.

  In the current interrupt device 302, the size of the hole or notch provided in the contact plate 5 is adjusted so that the gap between the contact plate 5 and the energizing plate 4 is 1 mm or more in the third state. If the clearance between the contact plate 5 and the energizing plate 4 is 1 mm or more, the contact plate 5 and the energizing plate 4 do not re-conduct. That is, the state in which the energization path is interrupted can be maintained, and the electrode assembly 60 and the negative electrode external terminal 19 can be reliably prevented from re-conducting.

  The features of the current interrupt device 302 can be applied to all the embodiments described above. That is, in all of the above-described embodiments, the force at which the contact plate 5 moves to the energizing plate 4 side at a position where the contact plate 5 does not conduct with the energizing plate 4 after a predetermined time has elapsed since the energization path is interrupted. You may adjust so that the force which the deformation | transformation board 3 reverses may be balanced.

  Points to be noted regarding the technology described in the embodiments will be described. In the example, a current interrupting device was inserted between the negative external terminal and the electrode assembly (battery body). The current interrupting device may be inserted between the positive external terminal and the electrode assembly.

  The current-carrying plate is made so that the fracture portion breaks when a predetermined load is applied. Here, the “predetermined load” (a load having a predetermined magnitude) is set according to the case internal pressure (internal pressure threshold) when the current is to be interrupted. For example, the predetermined load is set to a load obtained by multiplying the internal pressure threshold value by the area of the deformation plate. The deformed plate is instantaneously deformed by jumping and buckling, and the load received by the fractured portion is a load obtained by multiplying the internal pressure threshold by the area of the deformed plate, and an impact load at which the punching projection collides with the fractured portion. Therefore, when the magnitude of the “predetermined load” is set to a load obtained by multiplying the internal pressure threshold value by the area of the deformed plate, the fractured portion is surely broken by deformation due to jumping buckling of the deformed plate. The energizing plate is made so that the fractured portion breaks when a predetermined load is applied. The “predetermined load” here is determined according to the predetermined level of the case internal pressure at which the current interrupting device is to be operated. It is done.

  The casing 11 of the embodiment corresponds to an example of a “tubular support member”. In the current-carrying plate of the example, the fracture portion was defined by the groove. Instead of the groove, the fracture portion may be defined by perforation (perforation or a row of pores provided at regular intervals). The size / depth of the groove or the shape of the perforation is determined so that the groove breaks when a predetermined threshold load is applied to the broken portion.

  In the embodiment, one surface of the deformable plate faces the case internal space (space 91 in the figure). In this case, the case internal space corresponds to “a first space maintained at the same pressure as the case internal pressure”. Moreover, the internal space (the space 92 in the figure) of the current interrupting device 2 sealed with respect to the internal space of the case corresponds to the “second space isolated from the internal space of the case”. The deformation plate has one surface facing the space 91 and the other surface facing the space 92. In other words, the deformation plate constitutes a part of the partition wall that separates the internal space of the current interrupting device 2 from the internal space of the case. When the case is filled with an electrolytic solution, the deformation plate exposed to the case internal space may be covered with a silicon sheet or the like in order to prevent deterioration of the deformation plate. Since the silicon sheet is flexible, it deforms according to the internal pressure of the case. That is, the space between the deformation plate and the silicon sheet corresponds to a space maintained at the same pressure as the case internal pressure. Accordingly, when the deformable plate is covered with a silicon sheet or the like, the space between the silicon sheet and the deformable plate corresponds to the “first space maintained at the same pressure as the case internal pressure”.

  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: Current interruption device / 3, 25: Deformation plate / 4: Current supply plate / 5, 105: Contact plate / 6: Breaking portion / 7: Sealing lid / 11: Housing / 12 Punching projection / 13: connecting member / 14, 17: seal member / 15: center portion / 16: fracture groove / 18: recessed portion / 19: negative electrode external terminal / 20: crimping member / 24: top surface / 60: electrode set Solid / 91: Space maintained at the same pressure as the case internal pressure / 92: Space isolated from the inside of the case and not affected by the internal pressure of the case / 100, 200, 300: Power storage device / 119: Positive electrode external terminal

Claims (10)

The electrode assembly and the positive or negative external terminal are electrically connected, and when the internal pressure of the case housing the electrode assembly rises above a predetermined level, the electrode assembly and the external terminal A current interrupting device that interrupts the energization path,
The current interrupt device is
An energizing plate provided with a breaking portion that breaks when a predetermined load is applied by the internal pressure at the predetermined level and moves in the pressure receiving direction of the internal pressure;
A contact plate disposed opposite to the energizing plate and electrically connected to the fracture portion;
A deformation plate that deforms when the internal pressure rises above a predetermined level; and
With
The energizing path passes through the energizing plate and the contact plate in order from the electrode assembly, or sequentially from the electrode assembly through the contact plate and the energizing plate,
The deforming plate faces the first space where one surface is maintained at the same pressure as the internal pressure, and the energization is performed in the second space where the other surface is isolated from the internal space of the case. Is opposed to the current plate and is disposed on the opposite side of the contact plate, and is deformed to the current plate side when the internal pressure rises above a predetermined level, and the fracture portion To give a predetermined load to break,
The deformation plate and the contact plate are fixed inside a cylindrical support member, and the area of the contact plate is smaller than the area of the deformation plate.   The current interrupting device according to claim 1, wherein the bending rigidity of the contact plate in the out-of-plane direction is lower than the bending rigidity of the deforming plate in the out-of-plane direction.   The current interrupting device according to claim 1 or 2, wherein the contact plate is provided with a hole or a notch.   4. The current according to claim 3, wherein the contact plate has a point-symmetric shape with respect to a center of the contact plate when viewed from a stacking direction of the contact plate, the deformation plate, and the energization plate. Shut-off device.   The deformation plate is formed in a mortar shape that protrudes toward the first space, and when the internal pressure rises above a predetermined level, the deformation plate jumps into a mortar shape that protrudes toward the second space and causes buckling. The current interrupting device according to any one of claims 1 to 4, wherein the current interrupting device is deformed.   The power storage device according to claim 5, wherein the rupture portion is provided at a central portion of the energization plate.   The current interrupting device according to any one of claims 1 to 6, wherein a punching protrusion that protrudes toward the fracture portion is provided at a central portion of the deformable plate.   The current interrupt device according to any one of claims 1 to 7, wherein a break groove or a perforation is provided so as to surround the break portion. When the internal pressure is less than a predetermined level, from the first state in which a gap is provided between the punching protrusion and the fracture portion,
When the internal pressure rises above a predetermined level, the punching protrusion of the deformation plate moves toward the energizing plate, applies an impact to the breaking portion and the contact plate, and To the second state of separating from the energization plate,
Transition to a third state in which the force of the contact plate moving toward the energizing plate and the force of the deforming plate separating the contact plate from the energizing plate are balanced,
The current interrupting device according to claim 7 or 8, wherein, in the third state, the contact plate is separated from the energizing plate so as not to conduct with the energizing plate.   An electrical storage apparatus provided with the electric current interruption apparatus of any one of Claim 1 to 9.

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