JP6123648B2 - Power storage device - Google Patents

Description

  This specification discloses the technique regarding the electrical storage apparatus provided with the electric current interruption apparatus.

  In the technical field of power storage devices, development of a current interrupting device that cuts off the current flowing between the electrode terminals (positive electrode terminal and negative electrode terminal) when the power storage device is overcharged or when a short circuit occurs inside is underway. . The current interrupting device is disposed between the electrode terminal and the electrode (between the positive electrode terminal and the positive electrode or between the negative electrode terminal and the negative electrode). In Patent Document 1, an electrode member and an electrode are electrically connected by connecting a deforming member (diaphragm) to the electrode terminal, connecting an energizing member (connecting metal) to the electrode, and joining the deforming member to the energizing member. An apparatus is disclosed. In the power storage device of Patent Document 1, when the pressure in the power storage device increases, the deformable member separates from the current-carrying member, and conduction between the electrode terminal and the electrode is interrupted.

JP 2012-157451 A

  In order to operate the current interrupting device reliably, it is necessary to join the deformable member and the energizing member to such an extent that the deformable member can be separated from the energized member. That is, since the deformable member is separated from the energizing member according to the internal pressure in the power storage device, the deformable member and the energizing member cannot be firmly joined. Therefore, when the electrode assembly contacts the current interrupt device, the current interrupt device may malfunction or be damaged. In particular, when the power storage device is further reduced in size, the distance between the current interrupt device and the electrode assembly becomes closer, and the electrode assembly may come into contact with the current interrupt device due to vibration or the like, and an impact may be applied to the current interrupt device. This specification provides the technique which prevents that a malfunction arises in an electric current interruption apparatus.

  The power storage device disclosed in this specification includes a case, an electrode assembly, an electrode terminal, a current interrupt device, and a contact prevention structure. The electrode assembly is accommodated in the case and includes a positive electrode and a negative electrode. The electrode terminal passes through the inside and outside of the case. The current interrupting device is accommodated in the case, and is disposed between the electrode terminal and the energization path of the electrode assembly. The current interrupting device switches the electrode terminal and the positive electrode or the negative electrode from a conducting state to a non-conducting state when the pressure in the case exceeds a predetermined value. The contact prevention structure is provided between the electrode assembly and the current interrupting device in a direction connecting the electrode assembly and the current interrupting device. The contact prevention structure prevents the electrode assembly from contacting the current interrupt device.

  Since the power storage device described above can prevent the electrode assembly from coming into direct contact with the current interrupt device, even if vibration or the like is applied to the power storage device and the electrode assembly moves toward the current interrupt device, the current It is possible to suppress an impact from being applied to the blocking device. Therefore, it is possible to prevent the current interrupting device from malfunctioning or the current interrupting device from being damaged. Therefore, a highly reliable power storage device can be realized.

  Note that “the contact prevention structure is provided between the electrode assembly and the current interrupting device in the direction connecting the electrode assembly and the current interrupting device” means that the electrode assembly and the current interrupting device are connected (hereinafter referred to as “the contact preventing structure”). , Referred to as the first direction), the contact prevention structure is not limited to the form that overlaps the electrode assembly and the current interrupt device. The contact prevention structure includes a plane (hereinafter referred to as a first plane) perpendicular to the first direction including the end of the electrode assembly on the current interrupting device side and a first end including the end of the current interrupting device on the electrode assembly side. What is necessary is just to be provided between the planes (henceforth a 2nd plane) orthogonal to a direction.

  According to the technique disclosed in the present specification, it is possible to prevent a malfunction from occurring in the current interrupt device.

Sectional drawing of the electrical storage apparatus of 1st Example is shown. Sectional drawing of the electrical storage apparatus of 2nd Example is shown. Sectional drawing of the electrical storage apparatus of 3rd Example is shown. An example of an electric current interruption apparatus is shown. The other example of an electric current interruption apparatus is shown.

  Hereinafter, some technical features of the power storage device disclosed in this specification will be described. The items described below have technical usefulness independently.

  The power storage device includes a case, an electrode assembly, an electrode terminal, a current interrupt device, and a contact prevention structure. The electrode assembly is housed in a case and may include a positive electrode and a negative electrode. Further, an insulator may be provided on the inner wall of the case to insulate the case from the electrode assembly. The electrode terminal may pass through the inside and outside of the case. That is, a part of the electrode terminal may be located outside the case, and the other part of the electrode terminal may be located inside the case. The current interrupt device may be connected to the negative terminal and the negative electrode. In this case, the current interrupt device is disposed on the energization path between the negative electrode terminal and the negative electrode, and switches the negative electrode terminal and the negative electrode from the conductive state to the non-conductive state when the internal pressure of the case exceeds a predetermined value. The current interruption device may be connected to the positive electrode terminal and the positive electrode. In this case, the current interrupt device is disposed on the energization path between the positive electrode terminal and the positive electrode, and switches the positive electrode terminal and the positive electrode from the conductive state to the non-conductive state when the internal pressure of the case exceeds a predetermined value.

  The contact prevention structure may be provided between the electrode assembly and the current interrupting device in a direction (first direction) connecting the electrode assembly and the current interrupting device. Note that the contact prevention structure does not necessarily exist between the electrode assembly and the current interrupt device. The contact prevention structure has a flat surface (first plane orthogonal to the first direction) in which the end of the electrode assembly on the side of the current interruption device extends horizontally and an end of the current interruption device on the side of the electrode assembly in the horizontal direction. What is necessary is just to arrange | position between planes (2nd plane orthogonal to a 1st direction). The contact prevention structure may be any structure that prevents the electrode assembly from directly contacting the current interrupt device when the electrode assembly moves toward the current interrupt device.

  The electrode terminal includes a positive electrode terminal and a negative electrode terminal, and both the positive electrode terminal and the negative electrode terminal may be disposed on the same wall of the case. In this case, the distance between the end on the electrode assembly side of at least one of the positive electrode terminal and the negative electrode terminal and the end on the electrode terminal (positive electrode terminal and negative electrode terminal) side of the electrode assembly is the end on the electrode assembly side of the current interrupt device. It may be shorter than the distance between the part and the end of the electrode assembly on the current interrupting device side. That is, the distance between the positive electrode terminal and the electrode assembly or the negative electrode terminal and the electrode assembly may be shorter than the distance between the current interrupt device and the electrode assembly. Alternatively, both the distance between the positive electrode terminal and the electrode assembly and the distance between the negative electrode terminal and the electrode assembly may be shorter than the distance between the current interrupt device and the electrode assembly. In this case, a part of the positive electrode terminal and / or the negative electrode terminal is located between the first plane and the second plane. The positive electrode terminal and / or the negative electrode terminal function as a contact prevention structure.

  When the distance between at least one of the positive electrode terminal and the negative electrode terminal and the electrode assembly is shorter than the distance between the current interruption device and the electrode assembly, the distance between the positive electrode terminal and the electrode assembly is less than the distance between the current interruption device and the electrode assembly. It may be shorter than the distance. That is, the positive electrode terminal may have a contact prevention structure. Thereby, the length of the negative electrode terminal can be made shorter than the length of the positive electrode terminal. Typically, the negative electrode material (eg, copper) is more expensive than the positive electrode material (eg, aluminum). By reducing the length of the negative electrode terminal (decreasing the size of the negative electrode terminal), the material cost of the power storage device can be suppressed. In this case as well, only the positive terminal may function as a contact prevention structure, or both the positive terminal and the negative terminal may function as a contact prevention structure.

  The contact prevention structure may be a buffer member disposed between the electrode assembly and the current interrupt device. The buffer member may be an elastic member that is not fixed to both the electrode assembly and the current interrupt device. In this case, when the electrode assembly moves to the current interrupting device side, the electrode assembly and the current interrupting device are indirectly contacted via the buffer member. In other words, the electrode assembly does not directly contact the current interrupt device. The buffer member can mitigate an impact applied to the current interrupt device from the electrode assembly.

  The current interrupt device may include a first energizing member, a second energizing member, an insulating member, and a deforming member. The first energization member may be fixed to the case of the power storage device. The first conductive member may be a part of the positive electrode terminal or a part of the negative electrode terminal. The 2nd electricity supply member may be arrange | positioned in the position which has a space | interval with a 1st electricity supply member and opposes a 1st electricity supply member. That is, the 1st electricity supply member and the 2nd electricity supply member do not need to contact directly. The second energizing member may be provided between the deformable member and the electrode assembly.

  The insulating member may be disposed between the first energizing member and the second energizing member. Moreover, the space | interval of a 1st electricity supply member and a 2nd electricity supply member may be maintained with the insulating member. That is, outside the range where the insulating member is provided, a gap may be provided between the first energizing member and the second energizing member.

  The deformable member is disposed between the first energizing member and the second energizing member, and may be fixed to the first energizing member inside the insulating member. The deformable member may be fixed to the first energizing member in a non-contact state with the insulating member. The deformable member may be in contact with the second energizing member when the pressure in the case is equal to or less than a predetermined value. The end of the deformable member may be separated from the second energizing member, and the center of the deformable member may be in contact with the center of the second energizing member. Further, the deformable member may be out of contact with the second energizing member when the pressure in the case exceeds a predetermined value. The deformable member may be reversed so as to be separated from the second energizing member when the pressure in the case exceeds a predetermined value. When the pressure in the case exceeds a predetermined value, the central portion of the second energizing member may be broken and the deformable member may be separated from the second energizing member.

  Both the deformable member and the second current-carrying member may be provided on the conduction path between the electrode terminal and the electrode. A deforming member is connected to one of the electrode terminal and the electrode, a second energizing member is connected to the other of the electrode terminal and the electrode, and the electrode terminal is disconnected when conduction between the deforming member and the second energizing member is interrupted And the other of the electrodes is insulated from the deformable member, and one of the electrode terminal and the electrode may be insulated from the second energizing member.

  The thickness of the center part of the second energizing member may be thinner than the thickness of the end part. Furthermore, a rupture groove may be provided at the center of the second energization member, which becomes a rupture starting point when the pressure in the case exceeds a predetermined value. The breaking groove may be continuously or intermittently made in the center of the second energizing member. The central portion of the deformable member may be fixed to the second energizing member at a position surrounded by the fracture groove.

  The current interrupt device may include two deformation members (a first deformation member and a second deformation member). In this case, the 2nd electricity supply member may be provided between the 1st deformation member and the 2nd deformation member. The second deformation member may be provided between the second energization member and the electrode assembly. The second deformable member may be provided with a protrusion protruding toward the second energizing member on the second energizing member side. In other words, the second deformable member may be provided on the side opposite to the deformable member with respect to the second energizing member, and may include a protrusion protruding toward the second energizing member on the second energizing member side. . The protrusion may face a portion surrounded by the groove of the energizing member in a state of being separated from the energizing member. The protrusion may be insulative.

  When the internal pressure of the case is less than or equal to a predetermined value, the second deforming member is present at the first position where the central portion protrudes in a direction away from the second energizing member, and when the internal pressure of the case exceeds the predetermined value The center part may exist in the 2nd position which protrudes toward the 2nd electricity supply member.

  As examples of the power storage device disclosed in this specification, a secondary battery, a capacitor, and the like can be given. As an example of an electrode assembly of a secondary battery, a stacked electrode assembly in which a plurality of cells having electrode pairs (a negative electrode and a positive electrode) opposed via a separator are stacked, and a sheet having an electrode pair opposed via a separator And a wound electrode assembly in which the cells are spirally processed. Further, the power storage device disclosed in this specification is mounted on, for example, a vehicle and can supply electric power to a motor. Hereinafter, the structure of the power storage device will be described.

  In the following description, a power storage device in which both the positive electrode terminal and the negative electrode terminal are exposed in one direction of the case will be described. However, in the technique disclosed in this specification, the case functions as an electrode terminal of one polarity (for example, positive electrode) and the electrode terminal of the other polarity (for example, negative electrode) is insulated from the case, like a cylindrical battery. The present invention can also be applied to a power storage device of a type that is fixed to a case in a state of being damaged. In the following description, a power storage device in which a current interrupting device is connected to a negative electrode terminal and a negative electrode will be described. The technology disclosed in this specification can also be applied to a power storage device in which a current interrupting device is connected to a positive electrode terminal and a positive electrode.

(First embodiment)
The structure of the power storage device 100 will be described with reference to FIG. The power storage device 100 includes a case 2, an electrode assembly 24, a positive terminal 4, a negative terminal 16, and a current interrupt device 20. The case 2 is made of metal and has a substantially rectangular parallelepiped shape. Inside the case 2, an electrode assembly 24 and a current interrupting device 20 are accommodated. The electrode assembly 24 includes a positive electrode and a negative electrode (not shown). The positive electrode tab 10 is fixed to the positive electrode, and the negative electrode tab 12 is fixed to the negative electrode. The inside 22 of the case 2 is filled with the electrolytic solution, and the atmosphere is removed. An insulating member 6 is attached to the inner wall of the case 2. The electrode assembly 24 is insulated from the case 2 by the insulating member 6.

  The positive electrode terminal 4 and the negative electrode terminal 16 pass through the inside and outside of the case 2. The positive terminal 4 and the negative terminal 16 are disposed on the same wall of the case 2. That is, both the positive electrode terminal 4 and the negative electrode terminal 16 are disposed in the same direction with respect to the electrode assembly 24. One end of the positive electrode terminal 4 is located outside the case 2, and the other end is located in the case 2. Similarly, one end of the negative electrode terminal 16 is located outside the case 2, and the other end is located in the case 2. The length of the negative electrode terminal 16 is shorter than the length of the positive electrode terminal 4. More specifically, the length of the negative electrode terminal 16 inside the case 2 is shorter than the length of the positive electrode terminal 4 inside the case 2. The positive terminal 4 and the negative terminal 16 are insulated from the case 2, respectively. Note that either the positive electrode terminal 4 or the negative electrode terminal 16 may be electrically connected to the case 2.

  A current interrupt device 20 is directly connected to the negative terminal 16. Specifically, the current interrupt device 20 is attached to the negative electrode terminal 16 between the negative electrode terminal 16 and the electrode assembly 24 in the direction connecting the negative electrode terminal 16 and the electrode assembly 24 (first direction A1). Details of the current interrupt device 20 will be described later. A negative electrode lead 14 connected to the negative electrode tab 12 is connected to the current interrupt device 20. That is, the current interrupt device 20 is electrically connected to the negative electrode of the electrode assembly 24. The positive electrode lead 8 connected to the positive electrode tab 10 is connected to the positive electrode terminal 4. The positive terminal 4 is electrically connected to the positive electrode of the electrode assembly 24. An insulating member 5 is provided at the end of the positive electrode terminal 4 on the current interrupt device 20 side. As a material for the insulating member 5, a resin having corrosion resistance to the electrolytic solution such as polypropylene (PP), polyethylene (PE), ethylene propylene diene monomer (EPDM), and polyphenylene sulfide (PPS) can be used.

  In the power storage device 100, the negative electrode terminal 16 and the negative electrode tab 12 are electrically connected via the current interrupt device 20 when the pressure in the case 2 is equal to or lower than a predetermined value. That is, the negative electrode terminal 16 and the negative electrode are electrically connected. When the pressure in the case 2 exceeds a predetermined value, the current interrupt device 20 interrupts conduction between the negative electrode terminal 16 and the negative electrode tab 12 to prevent current from flowing through the power storage device 100.

  As shown in FIG. 1, a gap is provided between the positive electrode terminal 4, the negative electrode terminal 16, the current interrupt device 20, and the electrode assembly 24, and is not in contact with each other. The distance D1 between the positive terminal 4 and the electrode assembly 24 is smaller than the distance D2 between the current interrupt device 20 and the electrode assembly 24. More specifically, in the first direction A1, the distance D1 between the positive electrode terminal 4 and the portion of the electrode assembly 24 facing the positive electrode terminal 4 is equal to the current breaking device 20 and the portion of the electrode assembly facing the current breaking device 20. 24 is shorter than the distance D2.

  The end of the positive electrode terminal 4 on the electrode assembly 24 side is located between the electrode assembly 24 and the current interrupt device 20 in the first direction. More specifically, the end of the positive electrode terminal 4 on the electrode assembly 24 side is a plane (first plane) obtained by horizontally extending the end of the current interrupting device 20 on the electrode assembly 24 side in the first direction A1. The end of the electrode assembly 24 on the side of the current interrupting device 20 in the first direction A1 is positioned between a plane (second plane) extending horizontally.

  Advantages of the power storage device 100 will be described. As described above, the distance D1 is smaller than the distance D2. Therefore, for example, when vibration is applied to the power storage device 100 and the electrode assembly 24 moves toward the current interrupting device 20, the electrode assembly 24 contacts the positive electrode terminal 4 and moves toward the current interrupting device 20. Stop. Therefore, the electrode assembly 24 does not contact the current interrupt device 20. The positive electrode terminal 4 functions as a contact prevention structure that prevents the electrode assembly 24 from contacting the current interrupt device 20.

  Another advantage of the power storage device 100 will be described. As described above, the insulating member 5 is fixed to the end face of the positive electrode terminal 4. Even if the electrode assembly 24 contacts the positive electrode terminal 4, it is possible to prevent the positive electrode and the negative electrode from being short-circuited. Further, the size of the negative electrode terminal 16 is smaller than the size of the positive electrode terminal 4. In general, the material of the negative electrode terminal is often more expensive than the material of the positive electrode terminal. For example, when copper (Cu) is used as the material of the negative electrode terminal 16 and aluminum (Al) is used as the material of the positive electrode terminal 4, the size of the negative electrode terminal 16 is made smaller than the size of the positive electrode terminal 4. An increase in cost can be suppressed.

(Second embodiment)
The power storage device 100a will be described with reference to FIG. The power storage device 100 a is a modification of the power storage device 100, and is different from the power storage device 100 in the form of the negative electrode terminal 16 a and the position of the current interrupt device 20. With respect to the power storage device 100a, the same components as those of the power storage device 100 may be denoted by the same reference numerals as those of the power storage device 100, and description thereof may be omitted.

  In the power storage device 100a, the current interrupt device 20 is not directly connected to the negative electrode terminal 16a. The current interrupt device 20 is disposed in the middle of the negative electrode lead 14 that connects the negative electrode terminal 16 a and the negative electrode tab 12. Specifically, the current interrupt device 20 is not disposed between the electrode assembly 24 and the negative electrode terminal 16a in the first direction A1. Further, in the first direction A1, the distance D3 between the negative electrode terminal 16a and the portion of the electrode assembly 24 facing the negative electrode terminal 16a is equal to the current interrupt device 20 and the portion of the electrode assembly 24 facing the current interrupt device 20. It is shorter than the distance D2. An insulating member 15a is provided at the end of the negative electrode terminal 16a on the current interrupt device 20 side. In the electricity storage layer 100 a, the negative electrode terminal 16 a functions as a contact prevention structure that prevents the electrode assembly 24 from contacting the current interrupt device 20. The positive electrode terminal 4 also functions as a contact prevention structure. In the power storage device 100a, both the positive electrode terminal 4 and the negative electrode terminal 16a function as a contact prevention structure.

(Third embodiment)
The power storage device 200 will be described with reference to FIG. The power storage device 200 is a modification of the power storage device 100, and is different from the power storage device 100 in the form of a contact prevention structure. With respect to the power storage device 200, the same components as those of the power storage device 100 may be denoted by the same reference numerals as those of the power storage device 100, and description thereof may be omitted.

  An insulating buffer member 215 is disposed between the electrode assembly 24 and the current interrupt device 20. The buffer member 215 is not fixed to either the electrode assembly 24 or the current interrupt device 20. The thickness D4 of the buffer member 215 is smaller than the distance D2 between the current interrupt device 20 and the portion of the electrode assembly 24 facing the current interrupt device 20. Therefore, a gap is provided between the buffer member 215 and the current interrupt device 20 and / or between the buffer member 215 and the electrode assembly 24. FIG. 3 shows a state where a gap is provided between the buffer member 215 and the current interrupt device 20. The buffer member 215 covers substantially the entire surface of the electrode assembly 24.

  In the case of the power storage device 200, when the electrode assembly 24 moves toward the current interrupt device 20, the buffer member 215 is sandwiched between the electrode assembly 24 and the current interrupt device 20. In other words, the electrode assembly 24 contacts the current interrupt device 20 via the buffer member 215. The shock applied to the current interrupt device 20 from the electrode assembly 24 is alleviated by the buffer member 215, and the current interrupt device 20 can be prevented from being damaged. As the buffer member 215, commercially available sponge, PP, PE, EPDM, or the like can be used.

  In power storage device 200, since thickness D4 is smaller than distance D2, force is applied from buffer member 215 to current interrupting device 20 when electrode assembly 24 is in a normal state (a state where it is present at a predetermined position in the design). Can be prevented.

  In the power storage device 200, the size of the positive terminal 204 is equal to the size of the negative terminal 16. That is, the positive terminal 204 is smaller than the positive terminal 4 of the power storage device 100. Further, an insulating member is not provided at the end of the positive electrode terminal 204 (see also FIG. 1). Compared with power storage device 100, power storage device 200 can reduce the size of the positive electrode terminal and omit providing an insulating member at the end of the positive electrode terminal. Since the buffer member 215 covers almost the entire surface of the electrode assembly 24, even if the electrode assembly 24 comes into contact with the positive electrode terminal 204, it is possible to prevent the positive electrode and the negative electrode from being short-circuited.

  Hereinafter, the current interrupting device 20 will be described with reference to FIGS. 4 and 5. Hereinafter, two types of current interrupting devices 20 (20a, 20b) will be described. 4 and 5 show the state of the current interrupt device 20 when the power storage device 100 (200) is operating normally and the pressure in the case 2 is equal to or lower than a predetermined value. Note that the technology disclosed in this specification is not limited to a power storage device using the current interrupt device 20 described below.

  The current interrupt device 20 (20a) shown in FIG. 4 includes a support member 34, a metal terminal member 40, a metal breaking plate 50, a metal deformation member 44, and an insulating seal member 46. ing. The terminal member 40 is a part of the negative electrode terminal 16 (see FIG. 1) and is an example of a first energization member. The fracture plate 50 is disposed at a position facing the terminal member 40 with a space from the terminal member 40. The fracture plate 50 is an example of a second energizing member. Between the electrode assembly 24 (see also FIG. 1) and the case 2, the fracture plate 50, the deformable member 44, and the terminal member 40 are arranged in this order above the electrode assembly 24.

  The terminal member 40 passes through the inside and outside of the case 2. The facing surface 42 of the terminal member 40 that faces the fracture plate 50 is recessed toward the center. In other words, the facing surface 42 is inclined so as to move away from the fracture plate 50 as it goes from the end toward the center. The facing surface 42 means a surface of the terminal member 40 facing the fracture plate 50 where the deformable member 44 is not fixed. The terminal member 40 is fixed to the case 2 while being insulated from the case 2 by the insulating member 38. A gap between the terminal member 40 and the case 2 is sealed by a seal member 36.

  The support member 34 supports the terminal member 40, the fracture plate 50, and the deformation member 44. The support member 34 includes a metal outer portion 30 and an insulating inner portion 32 disposed inside the outer plate portion. The terminal member 40 and the fracture plate 50 are positioned by the outer portion 30. Specifically, the fracture plate 50 is fixed to the terminal member 40 by caulking the outer portion 30. The inner portion 32 insulates the terminal member 40 and the breaker plate 50 from each other.

  The insulating member 48 is disposed between the end 44 b of the deformable member 44 and the fracture plate 50. The insulating member 48 maintains the distance between the terminal member 40 and the fracture plate 50. That is, the insulating member 48 prevents the terminal member 40 and the fracture plate 50 from coming into direct contact. The insulating member 48 prevents the terminal member 40 and the fracture plate 50 from being directly connected.

  The deformable member 44 is a metallic diaphragm. The deformation member 44 is disposed between the terminal member 40 and the fracture plate 50. An end 44 b of the deformation member 44 is fixed to the terminal member 40. Specifically, the end 44 b of the deformation member 44 is welded to the terminal member 40. A central portion 44 a of the deformation member 44 protrudes away from the terminal member 40. In other words, the deformable member 44 approaches the fracture plate 50 as it goes from the end 44b to the central portion 44a.

  A central portion 44 a of the deformable member 44 is fixed to the fracture plate 50 inside the fracture groove 52. More specifically, when the current interrupting device 20a is viewed in plan (as viewed from above in FIG. 4), the central portion 44a is welded to the fracture plate 50 in a range surrounded by the fracture groove 52.

  A seal member 46 is provided between the terminal member 40 and the fracture plate 50. The seal member 46 is an insulating O-ring. The seal member 46 is disposed outside the insulating member 48. The seal member 46 insulates the terminal member 40 and the breaker plate 50 and keeps the inside 22 of the power storage device 100 (200) airtight. That is, the seal member 46 seals the terminal member 40 and the breaker plate 50 to block the space inside the current interrupt device 20 from the space outside the current interrupt device 20 (the space in the case 2).

  A negative electrode lead 14 is connected to the fracture plate 50. The fracture plate 50 is electrically connected to the negative electrode tab 12 through the negative electrode lead 14 (see also FIG. 1). The thickness of the central portion 50a of the breaking plate 50 is thinner than the thickness of the end portion 50b. In addition, a fracture groove 52 is provided in the central portion 50a. The breaking groove 52 continuously makes a round at the central portion 50a. As described above, the central portion 44 a of the deformable member 44 is fixed to the central portion 50 a of the fracture plate 50.

  When the internal pressure of the case 2 is equal to or lower than a predetermined value, the negative electrode terminal 16 is electrically connected to the negative electrode through the terminal member 40, the deformable member 44, the fracture plate 50, the negative electrode lead 14, and the negative electrode tab 12. For example, when the power storage device 100 is overcharged or overheated, the internal pressure of the case 2 increases and exceeds a predetermined value. When the internal pressure of the case 2 exceeds a predetermined value, the fracture plate 50 is fractured starting from the fracture groove 52. As a result, the deformable member 44 and the fracture plate 50 are separated, and the deformable member 44 and the fracture plate 50 become non-conductive. Since the negative electrode terminal 16 and the negative electrode become non-conductive, it is possible to prevent a current from flowing between the positive electrode terminal 4 and the negative electrode terminal 16 (see also FIG. 1). When the break plate 50 is broken, the central portion 44a of the deformable member 44 moves from the break plate 50 side toward the terminal member 40 side. In other words, the deformable member 44 is inverted. As described above, since the facing surface 42 of the terminal member 40 is recessed, the terminal member 40 does not prevent the deformation member 44 from being reversed. It is possible to prevent the deformable member 44 and the fracture plate 50 from re-conducting after the fracture plate 50 is broken. That is, it is possible to prevent the current from flowing again between the positive electrode terminal 4 and the negative electrode terminal 16 after the pressure in the case 2 rises and the current interrupting device 20a is activated.

  The current interrupting device 20b will be described with reference to FIG. The same parts as those of the current interrupting device 20a may be denoted by the same reference numerals, and the description thereof may be omitted. The current interrupt device 20b includes two deformable members 44 and 60. In the following description, the first deformation member 44 and the second deformation member 60 are referred to.

  The second deformation member 60 is disposed on the opposite side of the fracture plate 50 from the first deformation member 44. That is, the fracture plate 50 is disposed between the first deformation member 44 and the second deformation member 60. An end portion 60 b of the second deformation member 60 is fixed to the fracture plate 50. Specifically, the end portion 60 b of the second deformation member 60 is welded to the end portion 50 b of the fracture plate 50.

  In the current interrupt device 20 b, the terminal member 40, the fracture plate 50, and the second deformation member 60 are supported by the support member 34. That is, the fracture plate 50 and the second deformation member 60 are fixed to the terminal member 40 by the support member 34. An insulating protrusion 58 is provided on the fracture plate 50 side of the second deformable member 60. The protrusion 58 is disposed at the central portion 60 a of the second deformable member 60 and protrudes toward the fracture plate 50. The protrusion 58 faces the central portion 50 a of the fracture plate 50. More specifically, when the current interrupting device 20b is viewed in plan (observed from the up and down direction in FIG. 5), the protrusion 58 is located within the range surrounded by the fracture groove 52.

  The 2nd deformation member 60 protrudes so that it may leave | separate from the fracture | rupture board 50 as it goes to the center part 60a from the edge part 60b. When the internal pressure of the case 2 is less than or equal to a predetermined value, a gap is provided between the protrusion 58 and the fracture plate 50. When the internal pressure of the case 2 exceeds a predetermined value, the second deformation member 60 is deformed toward the fracture plate 50. That is, the central portion 60a moves toward the central portion 50a of the fracture plate 50. In other words, the second deformation member 60 is reversed with the end 60b as a fulcrum. More specifically, when the internal pressure of the case 2 is less than or equal to a predetermined value, the central portion 60a of the second deformable member 60 exists at the first position protruding in a direction away from the fracture plate 50, and the internal pressure of the case 2 When the value exceeds a predetermined value, the central portion 60 a of the second deformable member 60 exists at the second position protruding toward the fracture plate 50. The protrusion 58 comes into contact with the breaking plate 50, and the breaking plate 50 breaks starting from the breaking groove 52. The fracture plate 50 and the first deformable member 44 become non-conductive, and the negative electrode terminal 16 and the negative electrode become non-conductive.

  When the second deformation member 60 is reversed, a part of the protrusion 58 is positioned above the fracture plate 50. In other words, the protrusion 58 passes through the central portion of the fracture plate 50. The protrusion 58 restricts the first deformable member 44 from moving downward (on the fracture plate 50 side). Therefore, it can prevent more reliably that the 1st deformation member 44 and the fracture | rupture board 50 conduct again.

  In the current interrupt device 20b, the second deformation member 60 separates the inside and the outside of the current interrupt device 20b. Therefore, the internal pressure change of the case 2 directly acts on the second deformation member 60. By using the second deformable member 60b that reverses according to the internal pressure of the case 2, the fracture plate 50 can be more reliably broken when the internal pressure of the case 2 exceeds a predetermined value. Further, by using the second deformable member 60, the fracture plate 50 can be interrupted from the outside of the current interrupt device 20b (inside the case 2). Even if an arc is generated when the breaking plate 50 is broken, it is possible to prevent the arc from coming into contact with the gas (for example, hydrogen) in the case 2.

  In the above-described current interrupt device 20 (20a, 20b), the terminal member 40 is a part of the electrode terminal (negative electrode terminal 16). The terminal member 40 itself may be a part of an external terminal for connecting an external wiring or the like, or an external terminal for connecting an external wiring or the like is provided separately from the terminal member 40, and the terminal member 40 and the external terminal are connected to a conductive member. You may connect with. Further, even if the deformable member (first deformable member) 44 is not directly fixed to the terminal member 40, a conductive lead is connected to the terminal member 40, and the deformable member (first deformable member) 44 is connected to the lead. Good. When the terminal member is a separate part from the electrode terminal, the terminal member and the electrode (positive electrode or negative electrode) may be connected, and the fracture plate (second energizing member) and the electrode terminal may be connected.

  The power storage device described above only needs to include a contact prevention structure that prevents the electrode assembly from directly contacting the current interrupt device when the electrode assembly moves toward the current interrupt device. For this reason, various materials can be used as the structure of the current interrupting device and the material of the parts constituting the power storage device. Hereinafter, materials of components constituting the power storage device will be exemplified for a lithium ion secondary battery which is an example of the power storage device.

  The electrode assembly will be described. The electrode assembly includes a positive electrode, a negative electrode, and a separator interposed at a position between the positive electrode and the negative electrode. The positive electrode has a positive electrode metal foil and a positive electrode active material layer formed on the positive electrode metal foil. A positive electrode tab is corresponded to the metal foil for positive electrodes in which the positive electrode active material layer is not apply | coated. The negative electrode has a negative electrode metal foil and a negative electrode active material layer formed on the negative electrode metal foil. A negative electrode tab is corresponded to the metal foil for negative electrodes in which the negative electrode active material layer is not apply | coated. Note that there are no particular limitations on materials (eg, active material, binder, and conductive additive) included in the active material layer, and materials that are used for electrodes of known power storage devices and the like can be used.

  As the metal foil for the positive electrode, aluminum (Al), nickel (Ni), titanium (Ti), stainless steel, or a composite material thereof can be used. In particular, aluminum or a composite material containing aluminum is preferable. Moreover, the material similar to the metal foil for positive electrodes can be used as a material of a positive electrode lead.

The positive electrode active material only needs to be a material in which lithium ions can enter and desorb, and Li ₂ MnO ₃ , Li (NiCoMn) _0.33 O ₂ , Li (NiMn) _0.5 O ₂ , LiMn ₂ O ₄ , LiMnO _2, LiNiO _2, and _{LiCoO 2, LiNi 0.8 Co 0.15 Al} 0.05 O 2, Li 2 MnO 2, LiMn 2 O 4 or the like can be used. In addition, alkali metals such as lithium and sodium, or sulfur can be used as the positive electrode active material. These may be used alone or in combination of two or more. A positive electrode active material is apply | coated to the metal foil for positive electrodes with a electrically conductive material, a binder, etc. as needed.

  As the metal foil for the negative electrode, aluminum, nickel, copper (Cu), or a composite material thereof can be used. In particular, copper or a composite material containing copper is preferable. Moreover, the material similar to the metal foil for negative electrodes can be used as a material of a negative electrode lead.

  As the negative electrode active material, a material in which lithium ions can enter and leave is used. Alkali metals such as lithium (Li) and sodium (Na), transition metal oxides containing alkali metals, natural graphite, mesocarbon microbeads, highly oriented graphite, carbon materials such as hard carbon, soft carbon, silicon alone or silicon A containing alloy or a silicon-containing oxide can be used. The negative electrode active material is particularly preferably a material that does not contain lithium (Li) in order to improve battery capacity. A negative electrode active material is apply | coated to the metal foil for negative electrodes with a electrically conductive material, a binder, etc. as needed.

  As the separator, a porous porous material is used. As the separator, a porous film made of a polyolefin-based resin such as polyethylene (PE) or polypropylene (PP), or a woven or non-woven fabric made of polypropylene, polyethylene terephthalate (PET), methyl cellulose or the like can be used.

The electrolytic solution is preferably a nonaqueous electrolytic solution in which a supporting salt (electrolyte) is dissolved in a nonaqueous solvent. As a non-aqueous solvent, a solvent containing a chain ester such as ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), ethyl acetate, A solvent such as methyl propionate or a mixture thereof can be used. Moreover, as a supporting salt (electrolyte), for _example, can be used LiPF _6, LiBF 4, LiAsF _6, and the like.

  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. In addition, the technical elements described in the present specification or 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 the present specification or the drawings can achieve a plurality of objects at the same time, and has technical utility by achieving one of the objects.

2: Case 4: Positive terminal (contact prevention structure)
16: Negative terminal 20: Current interruption device 24: Electrode assembly 100: Power storage device

Claims (3)

Case and
An electrode assembly housed in the case and comprising a positive electrode and a negative electrode;
An electrode terminal passing through the inside and outside of the case;
It is accommodated in the case, and is arranged between the electrode terminal and the energization path of the electrode assembly, and when the pressure in the case exceeds a predetermined value, the electrode terminal and the positive electrode or the positive electrode A current interrupting device for switching the negative electrode from a conductive state to a non-conductive state;
A contact prevention structure that is provided between the electrode assembly and the current interrupt device in a direction connecting the electrode assembly and the current interrupt device, and prevents the electrode assembly from contacting the current interrupt device; , equipped with a,
The electrode terminal includes a positive terminal and a negative terminal,
Both the positive terminal and the negative terminal are arranged on the same wall of the case,
A power storage device in which a distance between at least one of the positive electrode terminal and the negative electrode terminal and the electrode assembly is shorter than a distance between the current interrupt device and the electrode assembly . The positive terminal and the distance between the electrode assembly, the power storage device according to a short claim 1 than the distance between the electrode assembly and the current cutoff device. It said power storage device, a power storage device according to claim 1 or 2 is a secondary battery.

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