JP2015053145A - Secondary battery module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique consuming electric energy stored in a battery cell with a suppressed temperature rise inside a battery cell, when external force is added to a secondary battery module.SOLUTION: The secondary battery module includes three or more battery cells disposed in such a manner that mutual anode terminals are aligned and mutual cathode terminals are aligned. The secondary battery module is formed of a conductive material and having a plurality of conductive members for connecting between an anode terminal in one battery cell and a cathode terminal in another battery cell adjacent to the one battery cell, or connecting between a cathode terminal of one battery cell and an anode terminal of another battery cell. In the secondary battery module, each part of mutually adjacent conductive members is oppositely disposed so as to cause the adjacent conductive members to contact to conduction when the secondary battery module receives a load.

Description

  The technology disclosed in this specification relates to a secondary battery module.

  In a hybrid car or an electric vehicle, it is necessary to provide a battery with a relatively large output in order to supply electricity to the traveling motor. Patent Document 1 discloses a technique for forming a large capacity battery module by connecting a plurality of battery cells to each other by a plurality of flat bus bars. The battery cell is a lithium ion battery, a nickel cadmium battery, a nickel hydrogen battery, or the like. In a battery module in which battery cells are connected by a bus bar, adjacent bus bars may be arranged close to each other. In such a case, an insulating film or the like is usually provided on the surface of the bus bar in order to prevent the bus bars from conducting when adjacent bus bars come into contact with each other. In the battery module of Patent Document 1, an insulating laminate is applied to the surface of the bus bar.

Japanese Patent Laid-Open No. 2003-242956

  In a secondary battery such as a lithium ion secondary battery, when an external force is applied to the secondary battery due to impact or dropping, an internal short circuit may occur. When the internal short circuit occurs, the anode and the cathode may locally conduct in the secondary battery. The surfaces of the anode and the cathode are each covered with an active material. For this reason, a relatively large current flows through the active material in a portion where the anode and the cathode are conducted. Since the active material has a higher electrical resistance than a conductive material such as a metal, large Joule heat is generated. For this reason, there exists a possibility that the temperature inside a secondary battery may rise excessively. The excessive temperature rise here means rising to a temperature at which the active material constituting the electrode decomposes.

  The present specification provides a technique for solving the above problems. The present specification provides a technology for consuming electric energy stored in a battery cell while suppressing an increase in temperature in the battery cell when an external force is applied to the secondary battery module.

  The technology disclosed in this specification reduces heat generation inside the battery by skillfully utilizing the structure of a secondary battery module of a type in which a plurality of battery cells are connected by a conductive member. As described above, in the conventional secondary battery module, the adjacent conductive member is insulation-coated so as not to short-circuit. In the technology disclosed in this specification, contrary to the conventional technical idea, the conductive members are arranged close to each other so that the adjacent conductive members become conductive when the secondary battery module is deformed. The conductive member is left exposed at the portion disposed in the vicinity. In the technology disclosed in this specification, when the secondary battery module is deformed, a short circuit is intentionally generated outside the battery cell, thereby suppressing heat generation inside the battery cell.

  The secondary battery module disclosed in the present specification has three or more battery cells arranged such that the anode terminals are arranged in a line and the cathode terminals are arranged in a line. The secondary battery module is connected between an anode terminal in one battery cell and a cathode terminal in another battery cell adjacent to the one battery cell, or between a cathode terminal in one battery cell and an anode terminal in another battery cell. It has a plurality of conductive members that connect them. In the secondary battery module, when the secondary battery module is deformed by receiving a load from the outside, a part of the adjacent conductive member is a predetermined distance so that the adjacent conductive member comes into contact and conducts. Are facing each other. The “predetermined distance” is determined on the condition that adjacent conductive members come into contact with each other due to deformation of the secondary battery module.

  The secondary battery module is adjacent so that the adjacent conductive member contacts and conducts in a situation where the secondary battery module receives an external force and may cause an internal short circuit of the battery cell. The conductive members are opposed to each other with a predetermined distance. Here, each adjacent conductive member is connected to the anode terminal and the cathode terminal of the same battery cell, respectively. For this reason, when the adjacent conductive member comes into contact and conducts, the anode and the cathode of the battery cell are short-circuited through these conductive members. Here, the electrical resistance of each conductive member is lower than the electrical resistance of the active material inside the battery. For this reason, a temperature rise can be suppressed compared with the case where a battery cell short-circuits internally. Thereby, in said secondary battery module, the electrical energy stored in the battery cell can be consumed, suppressing the temperature rise of a battery cell.

1 is a perspective view showing a secondary battery module 2 of Example 1. FIG. 3 is a partial plan view showing a secondary battery module 2 of Example 1. FIG. 6 is a partial plan view showing a secondary battery module 102 of Example 2. FIG. It is a fragmentary top view which shows the secondary battery module 202 of a modification.

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

(Characteristic 1) In the secondary battery module disclosed in the present specification, the anode terminal and the negative terminal of the battery cell may be present at both ends in the longitudinal direction on one surface of the battery cell. The conductive member may extend in a longitudinal direction from a terminal of one battery cell and may be connected to a terminal of another adjacent battery via a bent portion that is bent toward the direction of another adjacent battery. Good. The bent portions may be opposed to each other so that the bent portions of the adjacent conductive members come into contact with each other when the secondary battery module is deformed by receiving a compressive load.

  In the secondary battery module described above, the bent portions of the adjacent conductive portions are opposed to each other, so that the adjacent conductive members are easily opposed to each other.

(Feature 2) In the secondary battery module disclosed in the present specification, a high resistance member having higher electrical resistance than the conductive member may be provided between adjacent conductive members. Contact between the conductive members when the secondary battery module is deformed by receiving a compressive load may be performed via the high resistance member.

  In said secondary battery module, when a secondary battery module receives a compressive load and deform | transforms, adjacent electrically-conductive members will conduct | electrically_connect through a high resistance member. For this reason, heat can be suitably generated in the high resistance member. As a result, electric energy can be consumed while suppressing heat generation inside the battery cell.

  As shown in FIG. 1, the secondary battery module 2 has four battery cells 3, 4, 5, and 6. The battery cells 3, 4, 5, 6 are specifically lithium ion batteries. However, the battery cells 3, 4, 5, and 6 may be other batteries such as a nickel metal hydride battery. The battery cells 3, 4, 5, 6 have the same shape. The battery cells 3, 4, 5, 6 have a substantially rectangular parallelepiped case 19. Anode terminals 11, 13, 15, 17 and cathode terminals 12, 14, 16, 18 are provided on the upper surface of the case 19 of the battery cells 3, 4, 5, 6, respectively. In addition, since the battery cells 3, 4, 5, and 6 are conventionally well-known lithium ion batteries, description of the internal structure is abbreviate | omitted. As battery cells 3, 4, 5, and 6, a wound type battery cell in which an anode, a cathode, and a separator are wound and accommodated in a case, and an anode, a cathode, and a separator are stacked and accommodated in a case Stacked battery cells can be used. The secondary battery module 2 is typically mounted on an electric vehicle and used as a device that stores driving power of a traveling motor.

  As shown in FIG. 1, the battery cells 3, 4, 5, 6 of the secondary battery module 2 are arranged in a line. When the three-dimensional coordinate system (see FIG. 1) is defined, the direction in which the battery cells 3, 4, 5, 6 are arranged is the x-axis direction, and the upper surface of the battery cell (the anode terminal and the cathode terminal are provided). The positive direction of the z-axis is the positive direction of the z-axis, the anode terminal of each battery cell is located at the end of the battery cell in the positive y-axis direction, and the negative terminal of each battery cell is the y-axis of the battery cell Located at the negative end. In other words, the anode terminals 11, 13, 15, 17 of the battery cells 3, 4, 5, 6 are arranged in a line along the x axis, and the cathode terminals 12, 14, 16, 18 are along the x axis. Are in a row. Each battery cell 3, 4, 5, 6 is arrange | positioned at fixed intervals. In addition, each battery cell 3, 4, 5, 6 is being fixed to the case 20 of the secondary battery module 2 by the lower surface. In FIG. 1, only a part of the case 20 is drawn in order to depict the internal structure of the secondary battery module, but it should be noted that the case 20 is a container that accommodates the entire plurality of battery cells.

  The secondary battery module 2 has bus bars 7, 8, 9. The bus bars 7, 8, and 9 are made of metal. As a material for forming the bus bars 7, 8, 9, for example, aluminum or copper can be used. The electric resistance of the bus bars 7, 8 and 9 is relatively low. The surfaces of the bus bars 7, 8, 9 are not provided with an insulating means such as an insulating coating. That is, the surfaces of the bus bars 7, 8, 9 have conductivity.

  The battery cells 3, 4, 5, 6 are connected in series by bus bars 7, 8, 9. Specifically, the cathode terminal 12 of the battery cell 3 and the anode terminal 13 of the battery cell 4 are the bus bar 7, the cathode terminal 14 of the battery cell 4 and the anode terminal 15 of the battery cell 5 are the bus bar 8, and the battery cell 5. The cathode terminal 16 and the anode terminal 17 of the battery cell 6 are connected by a bus bar 9.

  Below, the shape and arrangement | positioning of the bus bars 7, 8, and 9 are demonstrated using FIG. The shapes of the bus bars 7, 8, 9 are the same. Accordingly, when the shape of the bus bars 7, 8, 9 is described, the bus bar 8 will be described as a representative. As described above, the bus bar 8 connects the cathode terminal 14 of the battery cell 4 and the anode terminal 15 of the battery cell 5. The bus bar 8 is substantially S-shaped. However, as shown in FIG. 2, the shape of the bus bar 8 is exactly a shape obtained by inverting the S-shape, but such a shape is also referred to as “S-shape” in the present specification. The bus bar 8 extends upward from the position of the cathode terminal 14 in FIG. The bus bar 8 extending upward in FIG. 2 is bent toward the direction of the battery cell 5 (right direction in FIG. 2) at a substantially central position of the battery cell 4. At a position where the bus bar 8 is bent, a first contact portion 81 is formed on the left side of the bus bar 8 in FIG. The first contact portion 81 is a flat surface facing the upper left in FIG. The bent bus bar 8 extends toward the battery cell 5. The bus bar 8 extending in the direction of the battery cell 5 is bent toward the direction of the anode terminal 15 of the battery cell 5 (upward in FIG. 2) at the approximate center of the battery cell 5. At a position where the bus bar 8 is bent, a second contact portion 82 is formed on the right side of the bus bar 8 in FIG. The second contact portion 82 is a flat surface facing the lower right in FIG. The bent bus bar 8 extends toward the anode terminal 15 and reaches the anode terminal 15.

  The bus bar 7 is located on the left side of the bus bar 8. As shown in FIG. 2, the second contact portion 72 of the bus bar 7 is a flat surface facing the lower right in FIG. The first contact portion 81 of the bus bar 8 and the second contact portion 72 of the bus bar 7 face each other. A bus bar 9 is located on the right side of the bus bar 8. The first contact portion 91 of the bus bar 9 is a flat surface facing the upper left in FIG. The second contact portion 82 of the bus bar 8 and the first contact portion 91 of the bus bar 9 are opposed to each other. Here, the distance between the first contact portion 81 of the bus bar 8 and the second contact portion 72 of the bus bar 7 is referred to as a distance D.

  The shape of the bus bar 8 will be described using another expression. The bus bar 8 connects the cathode terminal 14 of the battery cell 4 and the anode terminal 15 of the battery cell 5. The bus bar 8 has a first contact portion 81 on the left side and a second contact portion 82 on the right side. The bus bar 8 is substantially S-shaped as described above. In other words, the bus bar 8 has two bent portions when viewed in plan. The first contact portion 81 is formed on the outer edge portion of one bent portion of the bus bar 8, and the second contact portion 82 is formed on the outer edge portion of the other bent portion.

  In the secondary battery module 2 of the present embodiment, a plurality of battery cells 3, 4, 5, 6 are connected by bus bars 7, 8, 9. Thereby, the secondary battery module 2 can be increased in output.

  In the secondary battery module 2 of the present embodiment, the second contact portion 72 of the bus bar 7 and the first contact portion 81 of the bus bar 8 face each other with a predetermined distance D therebetween. When the entire secondary battery module 2 (that is, the case 20) receives a compressive load in the vertical direction in FIG. 2, the case of each battery cell 3, 4, 5, 6 is compressed in the vertical direction and deforms. If the case of each battery cell 3, 4, 5, 6 is deformed, the inside of any battery cell may be damaged and a short circuit may occur. A material having a large electric resistance such as an active material exists inside the battery cell, and when a short circuit occurs through such a material, a member having a large electric resistance locally generates heat. Note that the case where the entire secondary battery module 2 receives a load is typically a case where a vehicle on which the secondary battery module 2 is mounted collides with an obstacle.

  On the other hand, when the case of each battery cell 3, 4, 5, 6 is compressed and deformed in the vertical direction, for example, the distance between the anode terminal 13 and the cathode terminal 14 of the battery cell 4 is shortened. Here, the bus bar 7 is connected to the anode terminal 13, and the bus bar 8 is connected to the cathode terminal 14. Accordingly, the second contact portion 72 of the bus bar 7 and the first contact portion 81 of the bus bar 8 approach each other and come into contact with each other. As described above, the surface of the bus bar 7 and the surface of the bus bar 8 are conductive. For this reason, when the 2nd contact part 72 of the bus bar 7 and the 1st contact part 81 of the bus bar 8 contact, the anode terminal 13 and the cathode terminal 14 of the battery cell 4 are short-circuited. Specifically, the anode terminal 13 of the battery cell 4, the bus bar 7, the bus bar 8, and the cathode terminal 14 of the battery cell 4 are electrically connected in this order. Here, as described above, the bus bars 7 and 8 have lower electrical resistance than the active material inside the battery cell. For this reason, unlike the case where the battery cell 4 is internally short-circuited, the battery cell 4 is prevented from locally generating heat inside. Thereby, the temperature rise of the battery cell 4 is suppressed. Therefore, in the secondary battery module 2 of the present embodiment, the electric energy stored in the battery cell 4 can be consumed while suppressing the temperature rise of the battery cell 4.

  In the secondary battery module 2 of the present embodiment, the electric member 7 and the bus bar 8 are in contact with each other even when the entire secondary battery module 2 is compressed in the left-right direction in FIG. That is, when the entire secondary battery module 2 is compressed in the left-right direction in FIG. 2, the distance in the left-right direction in FIG. 2 of each battery cell 3, 4, 5, 6 is reduced. Here, the bus bar 7 is connected to the anode terminal 13 of the battery cell 4, and the bus bar 8 is connected to the anode terminal 15 of the battery cell 5. Therefore, when the distance between the battery cell 4 and the battery cell 5 in the left-right direction in FIG. 2 is reduced, the second contact portion 72 of the bus bar 7 and the first contact portion 81 of the bus bar 8 come into contact with each other. Also in this case, the anode terminal 13 and the cathode terminal 14 of the battery cell 4 are short-circuited.

  The distance D is appropriately determined in advance so that the bus bar 7 and the bus bar 8 come into contact when the secondary battery module 2 receives an external force. For example, the distance D is determined so that the bus bar 7 and the bus bar 8 come into contact when the secondary battery module 2 receives a predetermined load. For example, the predetermined load can be set to be smaller than the breaking load of the case of the battery cells 3, 4, 5, 6. Moreover, the load of a predetermined magnitude | size can be made into the load when the deformation amount of the case of the battery cell 3, 4, 5, 6 becomes larger than a predetermined value. Further, the load having a predetermined magnitude may be a load smaller than the breaking load of the case 20 of the secondary battery module 2. Moreover, the load of a predetermined magnitude | size is good also as a load when the deformation amount of the case 20 of the secondary battery module 2 becomes larger than a predetermined value. If the distance D is set under any of the above conditions, the electric energy inside the battery cell can be consumed before the secondary battery module is destroyed, and even if the secondary battery module is destroyed after that, it is caused by electric leakage. Secondary damage can be avoided. Alternatively, the distance D can be determined based on the case size of the battery cells 3, 4, 5, 6. For example, the distance D can be set to 1/10 of the width W (see FIG. 2) in the lateral direction of FIG. Alternatively, the distance D can be determined based on the interval between the battery cells 3, 4, 5, 6. For example, the distance D can be smaller than the distance between the battery cells 3, 4, 5, 6.

  In the secondary battery module 2 of the present embodiment, the bus bars 7, 8, and 9 have the same shape. For this reason, the kind of component of the secondary battery module 2 is reduced. Moreover, in the secondary battery module 2 of a present Example, the bus bar 8 is formed in the substantially S shape. Moreover, the 1st contact part 81 is formed in the outer edge part in the one bending part of the bus bar 8, and the 2nd contact part 82 is formed in the outer edge part in the other bending part. Since the bus bar 8 has such a shape, adjacent conductive members can be easily opposed to each other. That is, since the contact parts facing each other have a shape protruding toward the contact part of the other party, the contact parts are easily opposed to each other. Further, for example, the contact portions can be made to face each other while suppressing an increase in volume and mass of the bus bar 8 as compared with a case where each of the bus bars 7, 8, 9 has a relatively simple shape such as a rectangle.

  FIG. 3 shows a partial plan view of the secondary battery module 102 of the second embodiment. In the secondary battery module 102 of the second embodiment, the bus bars 7, 8, 9 of the secondary battery module 2 of the first embodiment are changed to the bus bars 107, 108, 109. As described above, in the secondary battery module 2 of Example 1, the second contact portion 72 of the bus bar 7 is a flat surface facing the lower right, and the first contact portion 81 of the bus bar 8 is a flat surface facing the upper left. Met. On the other hand, in the bus bar of the second embodiment, the second contact portion 172 of the bus bar 107 and the first contact portion 181 of the bus bar 108 are surfaces having irregularities. The unevenness provided on the second contact portion 172 and the unevenness provided on the first contact portion 181 have corresponding shapes. That is, the distance between the second contact portion 172 and the first contact portion 181 is constant at each position in the range where the unevenness is provided.

  In the secondary battery module 102 of the second embodiment, as in the case of the secondary battery module 2 of the first embodiment, for example, when the bus bar 107 and the bus bar 108 approach the vertical direction in FIG. When approaching, the bus bar 107 and the bus bar 108 come into contact with each other. In the secondary battery module 102 of the second embodiment, for example, when the bus bar 107 moves obliquely from the upper right to the lower left in FIG. 3, the point 95 of the second contact portion 172 of the bus bar 107 is: The point 97 on the first contact portion 181 of the bus bar 108 is contacted. That is, in the secondary battery module 102 of the second embodiment, the bus bar 107 and the bus bar 108 are easily in contact with each other because the second contact portion 172 and the first contact portion 181 are provided with irregularities. As a result, the secondary battery module 102 of the present embodiment easily consumes the electric energy stored in the battery cell 4.

  When the secondary battery module of the embodiment is deformed by an external force and generates heat due to an internal short circuit in any of the battery cells, the short circuit is intentionally generated outside the battery cell to reduce the amount of heat generated inside. Suppress. Such a secondary battery module is suitable for in-vehicle use. Motor vehicles, particularly electric vehicles including hybrid vehicles, are equipped with a large capacity secondary battery module. The secondary battery module of the embodiment suppresses the amount of heat generated inside the battery because the secondary battery module is deformed to cause an internal short circuit in the battery cell when the electric vehicle collides. Can do.

  In the above embodiment, the secondary battery modules 2 and 102 have four battery cells 3, 4, 5, and 6. However, the secondary battery modules 2 and 102 only need to have three or more battery cells. That is, if there are three or more battery cells, the secondary battery modules 2 and 102 have two or more bus bars for connecting the battery cells. For this reason, the anode terminal and cathode terminal of a battery cell can be short-circuited via two bus bars.

  In the above embodiment, the plurality of battery cells 3, 4, 5, 6 are accommodated in the case 20. When the secondary battery module is mounted on an electric vehicle, the case that houses the plurality of battery cells may be the body of the electric vehicle. Moreover, each battery cell 3, 4, 5, 6 may be arrange | positioned closely mutually without spacing.

  Finally, a modification of the secondary battery module will be described (FIG. 4). In the secondary battery module 202 of the modification, the high resistance member 25 is provided at the first contact portion 81 of the bus bar 8. For this reason, when an external force is applied to the secondary battery module 202, the bus bars 7 and 8 are short-circuited via the high resistance member 25. The resistance value of the high resistance member 25 can be set as appropriate, but is preferably set as described below. The resistance value of the high resistance member 25 is set to be larger than the resistance values of the bus bars 7 and 8. For this reason, heat can be suitably generated in the high resistance member 25. As a result, electric energy can be consumed while suppressing heat generation inside the battery cell 4. Further, the resistance value of the high resistance member 25 is set so that the resistance value when the bus bars 7 and 8 are short-circuited via the high resistance member 25 is lower than the resistance value generated when the short circuit occurs inside the battery cell 4. Is done. For this reason, a current flows through the bus bars 7 and 8 surely. The high resistance member 25 may be provided integrally with the first contact portion 81 or the second contact portion 82 of the bus bar 8 (the same applies to the bus bars 7, 9, etc.) or provided separately from the bus bar 8. Also good. When the high-resistance member 25 is separate from the bus bar 8, for example, the high-resistance member 25 is provided at the approximate center of the bus bars 7 and 8 so that the bus bar 7 and the bus bar 8 come into contact with each other when an external force is applied. Also good.

  The bus bars 7, 8, 9, 107, 108, and 109 in the above-described embodiments and modifications are examples of the “conductive member” 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. 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.

2,102 Secondary battery module 3, 4, 5, 6 Battery cell 7, 8, 9, 107, 108, 109 Bus bar 11, 13, 15, 17 Anode terminal 12, 14, 16, 18 Cathode terminal 19 Case 81, 91,181 1st contact part 72,82,172 2nd contact part

Claims (3)

Three or more battery cells arranged such that the anode terminals are arranged in a row and the cathode terminals are arranged in a row;
A plurality of conductive connections between an anode terminal in one battery cell and a cathode terminal in another battery cell adjacent to the one battery cell, or between a cathode terminal in one battery cell and an anode terminal in another battery cell A secondary battery module having a member,
When the secondary battery module is deformed by receiving a compressive load, adjacent conductive members are in contact with each other so that the adjacent conductive members are in contact with each other.
Secondary battery module. An anode terminal and a negative electrode terminal in the battery cell are respectively present at both ends in the longitudinal direction on one surface of the battery cell,
The conductive member extends from the terminal of one battery cell in the longitudinal direction and is connected to the terminal of another adjacent battery via a bent portion that is bent toward the direction of another adjacent battery. Yes,
The secondary part according to claim 1, wherein the bent parts are opposed to each other so that the bent parts of the conductive members adjacent to each other when the secondary battery module is deformed by receiving a compressive load are deformed. Battery module. Between the adjacent conductive members, a high resistance member having a higher electrical resistance than the conductive member,
The secondary battery module according to claim 1 or 2, wherein the contact between the conductive members when the secondary battery module is deformed by receiving a compressive load is performed via the high resistance member.

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