JP2015146297A - power storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress an increase in the size of a case.SOLUTION: A power storage device 2 comprises: a case (a lid 3 and a case body 4); an electrode assembly 5, arranged in the case, which has a positive electrode, a negative electrode and a separator laminated on one another; an electrode terminal 14, fitted to the case, which is electrically connected to the electrode assembly; and a current cutoff device 6, arranged in the case, which can cut off a conduction path between the electrode assembly 5 and the electrode terminal 14. The case (3, 4) includes: a terminal wall 3 (the lid 3) to which the electrode terminal is fitted; and an adjacent wall which is adjacent to the terminal wall and is parallel to a lamination direction of the positive electrode, the negative electrode and the separator. The current cutoff device 6 is arranged between the electrode assembly 5 and the adjacent wall.

Description

  The present specification relates to a power storage 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. Patent Document 1 discloses a battery cell (an example of a power storage device) having a current interruption device (current interruption mechanism). The current interrupt device has a thin disk-shaped deformation plate (deformed metal plate). The deformation plate receives the pressure in the battery cell case on one side, and receives the pressure in the space isolated from the pressure in the case on the other side. An energization path is formed by the deformation plate and the conductive member (connection metal) contacting each other. When the pressure in the battery cell case becomes higher than a predetermined set pressure, the deformable plate is deformed and the deformable plate and the conductive member are separated. Thereby, the electric current of a battery cell is interrupted | blocked. The case has a terminal wall to which the electrode terminal is attached. The current interrupt device is disposed between the terminal wall and the electrode assembly.

JP 2010-157451 A

  In the above power storage device, the current interrupt device is disposed between the terminal wall and the electrode assembly. For this reason, it is necessary to enlarge the space between the terminal wall and the electrode assembly as much as the current interrupting device is arranged. As a result, there is a problem that a dead space is formed between the terminal wall and the electrode assembly, and the case is enlarged. This specification provides the technique which can suppress the enlargement of a case.

  The power storage device disclosed in this specification includes a case, an electrode assembly in which the positive electrode, the negative electrode, and the separator are stacked, and an electrode that is attached to the case and electrically connected to the electrode assembly A current interrupting device is provided that is disposed within the terminal and the case, is disposed on a current path between the electrode assembly and the electrode terminal, and is capable of interrupting the current path. The case has a terminal wall to which the electrode terminal is attached and an adjacent wall that is adjacent to the terminal wall and parallel to the stacking direction of the positive electrode, the negative electrode, and the separator. The current interrupt device is disposed between the electrode assembly and the adjacent wall.

  In the above power storage device, the current interrupt device is not disposed between the terminal wall and the electrode assembly, and the current interrupt device is disposed between the adjacent wall and the electrode assembly. For this reason, the distance between a terminal wall and an electrode assembly can be shortened, and it can suppress that a dead space is formed between these. On the other hand, a dead space is easily formed between the adjacent wall and the electrode assembly as much as the current interrupt device. However, the adjacent wall is parallel to the stacking direction of the electrode assembly (the stacking direction of the positive electrode, the negative electrode, and the separator). Generally, the surface area of the adjacent wall parallel to the stacking direction is made smaller than the surface area of the terminal wall. Therefore, compared with the case where a current interrupting device is arranged between the terminal wall and the electrode assembly, the dead space formed in the case can be reduced, and the enlargement of the case can be suppressed.

It is sectional drawing which shows the whole structure of the electrical storage apparatus of an Example. It is an expanded sectional view which shows the state before the action | operation of the electric current interruption apparatus mounted in the electrical storage apparatus of an Example. It is an expanded sectional view which shows the state after the action | operation of the electric current interruption apparatus of FIG. It is an expanded sectional view showing other examples of a current interrupting device.

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

(Characteristic 1) A current interrupting device for a power storage device disclosed in the present specification is a deformation that receives the pressure of the internal space of the case on one surface and receives the pressure of the space isolated from the internal space of the case on the other surface. A plate may be provided. Then, when the pressure in the internal space of the case exceeds a predetermined value, the energization path may be interrupted by the deformation of the deformation plate. In this case, one surface of the deformation plate (a pressure receiving surface that receives the pressure in the internal space of the case) may be parallel to the adjacent wall. In general, in a pressure-sensitive current interrupting device using a deformable plate, in order to increase the area of the pressure receiving surface (surface on which pressure acts) of the deformable plate, the dimension in the direction parallel to the deformable plate is likely to increase, The dimensions in the direction perpendicular to the deformation plate are easy to downsize. Therefore, the distance between the adjacent wall and the electrode assembly can be shortened by arranging the current interrupt device so that the pressure receiving surface of the deformable plate is parallel to the adjacent wall. As a result, the enlargement of the case can be further suppressed.

(Characteristic 2) The current interrupting device for a power storage device disclosed in the present specification may further include a contact plate and an energizing plate constituting an energizing path. The energization plate may be arranged so as to be sandwiched between the deformation plate and the contact plate. The energization plate may include a first contact portion that contacts the contact plate, and the contact plate may include a second contact portion that contacts the first contact portion. The deformation plate receives the pressure of the space isolated from the internal space of the case on the surface facing the contact plate, and receives the pressure of the internal space of the case on the surface opposite to the surface facing the contact plate Good. The deforming plate may be formed with a contact portion that contacts the first contact portion or the second contact portion when the energization path is interrupted. When the pressure in the internal space of the case exceeds a predetermined value, the second contact portion may be separated from the energizing plate by deforming the deformation plate so that the contact portion moves toward the contact plate.

  When the current interrupting device is disposed between the adjacent wall and the electrode assembly, the current interrupting device is more likely to come into contact with the electrolyte as compared with the case where the current interrupting device is disposed between the terminal wall and the electrode assembly. Sometimes. In the above power storage device, the contact portion between the energization plate and the contact plate is blocked from the internal space of the case by the deformation plate. Therefore, it can prevent suitably that a contact part deteriorates under the influence of electrolyte solution. In addition, hydrogen gas may be generated from the electrolytic solution. In the above power storage device, even if an arc (spark) is generated when the energization path is broken, the case where hydrogen gas is generated is not affected.

(Characteristic 3) In the power storage device disclosed in this specification, the case may be a rectangular parallelepiped case, and the terminal wall may be one of six walls constituting the rectangular parallelepiped case. In this case, when the case is viewed from the terminal wall side, the case may have a pair of first side walls extending in the first direction and a pair of second side walls extending in the second direction orthogonal to the first direction. Good. The length of the first side wall in the first direction may be longer than the length of the second side wall in the second direction, and the adjacent wall may be the second side wall. According to such a configuration, since the current interrupting device is arranged along the second side wall having a smaller surface area compared to the first side wall, the formation of a dead space in the case is suppressed, and the case is large. Can be suppressed.

  Hereinafter, examples of the current interrupt device and the power storage device disclosed in this specification will be described. 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.

  The power storage device 2 according to the embodiment is a secondary battery such as a nickel metal hydride battery or a lithium ion battery. The power storage device 2 is mounted on a vehicle such as a hybrid vehicle or an electric vehicle. The power storage device 2 supplies electric power to the motor, and is charged by electric power generated by the motor. As shown in FIG. 1, the power storage device 2 includes a case (3, 4), an electrode assembly 5 accommodated in the case (3, 4), a positive terminal 13 provided in the case (3, 4), and A negative electrode terminal 14 and a current interrupting device 6 provided in the case (3, 4) are provided.

  The case (3, 4) includes a case body 4 and a lid 3 that closes the opening 4 a of the case body 4. The case body 4 is a metal case and is formed in a substantially rectangular parallelepiped shape with one end released. Specifically, the dimension ly in the Y direction of the case body 4 is shorter than the dimension lz in the Z direction of the case body 4. Further, the dimension lx of the case body 4 in the X direction is longer than the dimension lz of the case body 4 in the Z direction. That is, the relationship of ly <lz <lx is established. Therefore, the area Syz of the pair of side walls (left and right side walls in FIG. 1) parallel to the YZ plane of the case (3, 4) is equal to the walls (upper and lower sides in FIG. 1) of the case (3, 4). ) Wall area Sxy. Further, the area Sxz of the pair of side walls (side walls before and after FIG. 1) parallel to the XZ plane of the case (3, 4) is equal to the wall (FIG. 1) of the case (3, 4) parallel to the XY plane. It becomes larger than the area Sxy of the upper and lower walls. That is, the relationship Syz <Sxy <Sxz is established. The opening 4 a of the case body 4 is hermetically closed by the lid 3.

  The lid 3 is provided with a positive terminal 13 at the right end in FIG. 1 and a negative terminal 14 at the left end in FIG. The positive terminal 13 is electrically connected to the positive electrode of the electrode assembly 5, and the negative terminal 14 is electrically connected to the negative electrode of the electrode assembly 5. The positive electrode terminal 13 and the negative electrode terminal 14 exchange electricity with the electrode assembly 5. Wiring (not shown) for charging / discharging the power storage device 2 is connected to the positive electrode terminal 13 and the negative electrode terminal 14. An insulating sheet (not shown) is disposed on the inner surface of the case body 4 and the inner surface (lower side in FIG. 1) of the lid 3. Thereby, the component in the case main body 4 and the case main body 4 (and the lid | cover 3) are insulated. The positive electrode terminal 13 and the negative electrode terminal 14 are insulated from the lid 3 by an insulator 15.

  The electrode assembly 5 includes a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode (not shown). Each of the positive electrode, the negative electrode, and the separator is formed in a sheet shape. The positive electrode, the negative electrode, and the separator are stacked in the Y direction on the coordinate axis shown in FIG. Each of the positive electrode and the negative electrode has a metal foil and an active material layer formed on the metal foil (not shown). A positive electrode tab 18 extends from the positive metal foil, and a negative electrode tab 19 extends from the negative metal foil. As shown in FIG. 1, the positive electrode tab 18 protrudes laterally (X direction (+)) from the side surface (YZ surface on the right side of FIG. 1) of the electrode assembly 5. The negative electrode tab 19 protrudes laterally (X direction (−)) from the side surface (the YZ surface on the left side in FIG. 1) of the electrode assembly 5.

  The electrode assembly 5 is immersed in a liquid electrolyte. The electrolytic solution contains a supporting salt containing a lithium salt in a solvent. For example, FEC (fluoroethylene carbonate) can be used as the solvent. As the supporting salt, for example, LiPF6 (lithium hexafluorophosphate) can be used. The electrolyte contains an aromatic monomer additive. When the electrode assembly 5 is overcharged, the monomer additive contained in the electrolyte is polymerized to generate hydrogen gas. As a result, the pressure in the internal space 10 of the case body 4 increases.

  As shown in FIG. 1, the positive electrode tab 18 and the positive electrode terminal 13 are connected by a wiring 16. Similarly, the negative electrode tab 19 and the negative electrode terminal 14 are connected by a wiring 17. The wiring 17 is provided with a current interrupt device 6. In other words, the current interrupt device 6 is provided in the energization path connecting the negative electrode and the negative electrode terminal 14. When the pressure in the case body 4 rises to a predetermined current interruption pressure value, the current interruption device 6 interrupts this energization path.

  The current interrupt device 6 is fixed to the inner surface of the lid 3. When the lid 3 is attached to the case main body 4, the current interrupting device 6 is disposed between the side wall of the case main body 4 (the side wall parallel to the YZ plane (the side wall on the left side in FIG. 1)) and the electrode assembly 5. The current interrupt device 6 is a pressure-sensitive current interrupt device. When the pressure in the case body 4 is less than the current cutoff pressure value, the current interrupt device 6 sets the current to flow through the energization path that connects the negative electrode and the negative electrode terminal 14. On the other hand, when the pressure in the case main body 4 is equal to or higher than the current interruption pressure value, the current interruption device 6 interrupts the energization path connecting the negative electrode and the negative electrode terminal 14 so that no current flows.

  Hereinafter, the current interrupt device 6 will be described in detail. FIG. 2 shows the state of the current interrupt device 6 when the pressure in the case body 4 is less than the current interrupt pressure value, and FIG. 3 shows the state of the current interrupt device 6 when the pressure exceeds the current interrupt pressure value. The current interruption device 6 changes the state of FIG. 2 to the state of FIG. 3, thereby interrupting the energization path that connects the negative electrode and the negative electrode terminal 14.

  As shown in FIG. 2, the current interrupt device 6 has a deformation plate 7. The deformation plate 7 is a diaphragm having a circular shape when viewed from the right side of FIG. 2 and has conductivity. The deformation plate 7 receives the pressure of the internal space 10 in the case main body 4 on the surface 8 (the surface on the right side in FIG. 1), and receives the pressure of the space 11 isolated from the internal space 10 on the surface 9. When the pressure in the case body 4 is less than the current interruption pressure value, the deformable plate 7 bulges to the right side in FIG. 2 as shown in FIG. The outer peripheral edge portion of the deformable plate 7 is sandwiched between the conductive member 24 and the support member 20 having an insulating property.

  The upper end 25 in FIG. 2 of the conductive member 24 is connected to the negative electrode terminal 14 (see FIG. 1). The outer peripheral edge portion of the deformable plate 7 is in contact with the conductive member 24 and both are electrically connected.

  A conductive member 21 is disposed on the right side of FIG. 2 of the deformation plate 7 (the side receiving the pressure in the case body 4). The conductive member 21 is supported by the support member 20. The outer peripheral edge of the deformable plate 7 and the conductive member 21 are insulated by a support member 20 having an insulating property. The central part of the deformation plate 7 and the conductive member 21 are fixed, and both are electrically connected. Specifically, the central portion of the deformation plate 7 and the conductive member 21 are welded. A vent hole 26 is provided in the support member 20. The vent hole 26 communicates the space inside the support member 20 (specifically, the space on the right side of the deformation plate 7 in FIG. 2) and the space in which the electrode assembly 5 is accommodated (the internal space 10 of the case body 4). doing.

  By electrically connecting the conductive member 24, the deformable plate 7, and the conductive member 21 in this order, a current flows through the energization path that connects the negative electrode of the electrode assembly 5 and the negative electrode terminal 14.

  As shown in FIG. 2, a fragile portion 22 is formed on the right side surface of the conductive member 21 in FIG. 2. The fragile portion 22 is formed in an annular shape so as to surround a range where the conductive member 21 and the deformation plate 7 are welded. The fragile portion 22 is a groove having a triangular cross section. In addition, the weak part 22 should just be that the breaking strength of the electrically-conductive member 21 is lower than another part, for example, can make a cross section square, a semicircle groove | channel, a sewing machine hole, etc. into a weak part.

  As described above, the surface 8 of the deformation plate 7 receives the pressure of the internal space 10 of the case body 4. For this reason, when the pressure in the case main body 4 rises, a leftward force in FIG. 2 is applied to the surface 8 of the deformation plate 7. When the pressure in the case body 4 becomes equal to or greater than the current interruption pressure value, the conductive member 21 is broken at the weakened portion 22 and the deformable plate 7 is deformed (FIG. 3). When the conductive member 21 is broken and the deformable plate 7 is deformed, no current flows through the energization path connecting the negative electrode and the negative electrode terminal 14. Note that the pressure receiving area of the deformable plate 7 and the breaking strength of the conductive member 21 are designed in advance so that the conductive member 21 is broken at the current cutoff pressure value.

  The dimension a (shown in FIG. 1) in the X direction of the current interrupting device 6 is shorter than the dimension b (shown in FIG. 1) in the Z direction. The dimension (not shown) of the current interrupting device 6 in the Y direction is shorter than the dimension ly in the Y direction of the case body 4 and is substantially the same as the dimension b of the current interrupting device 6 in the Z direction. In the current interrupt device 6, the pressure receiving area of the deformation plate 7 is secured by making the dimension b in the Y direction and the Z direction larger than the dimension a in the X direction.

  In the power storage device 2 of the present embodiment, the current interrupt device 6 is not disposed between the lid 3 to which the positive terminal 13 and the negative terminal 14 are attached and the electrode assembly 5. The positive electrode tab 18 and the negative electrode tab 19 protrude from the side surface (surface parallel to the YZ surface) of the electrode assembly 5 to the side (X direction). For these reasons, in the power storage device 2 of the present embodiment, the distance between the lid 3 and the electrode assembly 5 can be shortened. Thereby, it is possible to suppress the formation of a dead space between the lid 3 and the electrode assembly 5.

  On the other hand, the current interrupt device 6 is disposed between the side wall on the left side of the case body 4 in FIG. 1 and the electrode assembly 5, and a dead space is formed between them. However, the left side wall in FIG. 1 of the case body 4 is parallel to the stacking direction of the electrode assembly 5 (the stacking direction of the positive electrode, the negative electrode, and the separator), and the dimension ly in the Y direction is the dimension in the other direction of the case body 4. It becomes shorter than lx and lz. That is, the area Syz of the left side wall in FIG. 1 is smaller than the areas Sxy and Sxz of the other walls of the case body 4. Therefore, it is possible to suppress an increase in the dead space between the wall formed by the current interrupt device 6 and the electrode assembly. This reduces the dead space formed in the case (3, 4) compared to the case where the current interrupting device 6 is arranged between the lid 3 and the electrode assembly 5, and the case (3,4) ) Can be suppressed.

  Further, the current interrupt device 6 is disposed in the case (3, 4) so that the pressure receiving surface 8 of the deformation plate 7 is parallel to the left side wall of the case body 4 in FIG. That is, it arrange | positions so that the direction where the dimension of the electric current interruption apparatus 6 becomes the shortest may become X direction. Thereby, the distance between the side wall on the left side of FIG. 1 of the case body 4 and the electrode assembly 5 can be shortened, and the dead space formed between them can be reduced.

  The lid 3 in the embodiment is an example of “terminal wall” in the claims, and the side wall on the left side of FIG. 1 of the case body 4 is an example of “adjacent wall” in the claims.

  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.

  For example, in the above-described embodiment, the current interrupting device 6 is configured by the two plates of the deformable plate 7 and the conductive member 21, but the configuration of the current interrupting device is not limited to such a configuration. For example, like the electric current interruption apparatus 43 shown in FIG. 4, you may be comprised by three board | plate materials, the deformation | transformation board 44, the electricity supply board 49, and the contact plate 54. FIG. Specifically, the deforming plate 44, the energizing plate 50, and the contact plate 54 are disposed so as to be stacked, and the energizing plate 49 is disposed so as to be sandwiched between the deforming plate 44 and the contact plate 54. The energizing plate 50 is in contact with the contact plate 54 at the central portion 51 (an example of the first contact portion), and the contact plate 54 has a second contact portion 55 that is in contact with the central portion 51. The deformation plate 44 receives the pressure of the space 48 isolated from the internal space 20 of the case on the surface 46 facing the contact plate 54, and the interior of the case on the surface 45 opposite to the surface 46 facing the contact plate 54. The pressure of the space 10 is received. The deformation plate 44 is formed with a contact portion 47 that protrudes toward the energization plate 50. When the pressure in the internal space 10 of the case exceeds a predetermined value, the deforming plate 44 is deformed so that the contact portion 47 of the deforming plate 44 moves to the contact plate 54 side, whereby the energizing plate 49 is broken. Cut off current.

  When such a current interrupting device 43 is used, the contact portion between the energizing plate 49 and the contact plate 54 is interrupted from the internal space 10 of the case by the deformation plate 44. When the current interrupting device is arranged between the side wall of the case body 4 and the electrode assembly 5, the current interrupting device is more electrolytic than in the case where the current interrupting device is arranged between the lid 3 and the electrode assembly 5. Easier to contact with. In the current interrupting device 43, the contact portion between the energizing plate 49 and the contact plate 54 is interrupted from the internal space 10 of the case, and thus the contact portion is preferably prevented from being deteriorated by the influence of the electrolyte. can do.

  Further, in the above embodiment, the pressure receiving surface 8 of the deformation plate 7 of the current interrupting device 6 is arranged so as to be parallel to the side wall of the case body 4. The surface may be arranged so as to be orthogonal to the side wall of the case body 4.

  Further, in the above embodiment, the current interrupt device 6 is provided in the wiring 17 that connects the negative electrode terminal 14 and the negative electrode tab 19. However, the current interrupt device may be provided in the wiring 16 that connects the positive electrode terminal 13 and the positive electrode tab 18.

  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 Power storage device 3 Lid 4 Case main body 4a Opening 5 Electrode assembly 6, 43 Current interrupt device 7, 44 Deformation plate 10 Internal space 13 of case Positive electrode terminal 14 Negative electrode terminal 19 Negative electrode tab

Claims (4)

Case and
An electrode assembly disposed in the case and laminated with a positive electrode, a negative electrode, and a separator;
An electrode terminal attached to the case and electrically connected to the electrode assembly;
A current interrupting device disposed in the case, disposed on a current path between the electrode assembly and the electrode terminal, and capable of interrupting the current path;
The case has a terminal wall to which the electrode terminal is attached, an adjacent wall that is adjacent to the terminal wall and parallel to the stacking direction of the positive electrode, the negative electrode, and the separator,
The power storage device, wherein the current interrupt device is disposed between the electrode assembly and the adjacent wall. The current interrupt device is
A deforming plate that receives the pressure of the internal space of the case on one surface and receives the pressure of the space isolated from the internal space of the case on the other surface,
When the pressure in the internal space of the case exceeds a predetermined value, the energization path is cut off by the deformation of the deformation plate,
The power storage device according to claim 1, wherein one surface of the deformation plate is parallel to the adjacent wall. The current interrupt device is
Further comprising a contact plate and an energization plate constituting the energization path,
The energization plate is disposed so as to be sandwiched between the deformation plate and the contact plate,
The energization plate includes a first contact portion that contacts the contact plate,
The contact plate includes a second contact portion that contacts the first contact portion,
The deformation plate is
Receiving the pressure of the space isolated from the internal space of the case on the surface facing the contact plate, receiving the pressure of the internal space of the case on the surface opposite to the surface facing the contact plate, and An abutting portion that contacts the first contact portion or the second contact portion when the energization path is interrupted is formed,
When the pressure in the internal space of the case exceeds a predetermined value, the deforming plate is deformed so that the contact portion moves toward the contact plate, whereby the second contact portion is separated from the energizing plate.
The power storage device according to claim 1 or 2. The case is a rectangular parallelepiped case,
The terminal wall is one of six walls constituting a rectangular parallelepiped case,
When the case is viewed from the terminal wall side, the case has a pair of first side walls extending in a first direction and a pair of second side walls extending in a second direction orthogonal to the first direction.
The length of the first side wall in the first direction is longer than the length of the second side wall in the second direction,
The power storage device according to claim 1, wherein the adjacent wall is the second side wall.

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